ft t WA ths Lo yi ee Se he At nt Mu Keological Investigations of the Tundra Biome in the Prudhoe Bay Region, Alaska Edited by Jerry Brown, Director U.S. Tundra Biome U.S. Army Cold Regions Research and Engineering Laboratory Hanover, New Hampshire 03755 Biological Papers of the University of Alaska Special Report Number 2. October, 1975 BIOLOGICAL PAPERS OF THE UNIVERSITY OF ALASKA Editor JAMES E. MORROW Department of Biological Sciences University of Alaska Editorial Board GEORGE W. ARGUS National Museum of Natural Sciences, Ottawa |. McT. COWAN University of British Columbia, Vancouver WILLIAM G. PEARCY Oregon State University, Corvallis Library of Congress Catalog Card Number: 75-620095 Wh Abstract During the period 1970-1974, the U.S. Tundra Biome Program, which was stationed primarily out of Barrow, performed a series of environmental and terrestrial ecological studies at Prudhoe Bay. This volume reports specifically on the Prudhoe results and is divided into three major subdivisions: (1) abiotic and soil investi- gations; (2) plant investigations, and (3) animal investigations. The abiotic section contains papers on the air and soil temperature regimes; the snow cover, particularly its properties adjacent to the roadnet; major soil and landform associations, and the chemical composition of soils, runoff, lakes, and rivers. The plant section contains reports on a general vegetation survey; a follow-up vegetation mapping project, and a study of the growth of arctic, boreal, and alpine biotypes in an experimental transplant garden. The animal section contains reports on the tundra invertebrates; the bird, lemming, and fox populations, and the behavioral and physiological investigations of caribou and several experimental reindeer. Appendices contain a checklist of the vascular, bryophyte, and lichen flora of the Prudhoe Bay area and selected data on vegetation. Several of the papers draw comparisons with the Barrow tundra. The volume includes a considerable number of tables in its attempt to document for the first time the abiotic, flora, and fauna of this relatively unknown arctic tundra landscape. Sats hash j In Memoriam This volume is dedicated to the memory of Scott Parrish, who died in a plane crash on 26 August 1974. During the period 1971-1974, Scott was involved directly in many aspects of the Biome’s Prudhoe Bay research. This included arranging and expediting the program’s logistic requirements, design of experi- ments, data reduction for several projects, and overall guidance to Biome personnel on research activities and opportunities at Prudhoe. We considered Scott both a friend and scientific colleague. His thoughts on and concerns for the environment were highly respected. The loss of his experience and personal knowledge of the Prudhoe area is irretrievable. We hope that this volume will record for the future both Scott’s memory and his interests in the tundra. Vil rriadecnooreip vat @ 7 ’ oui BeAr ao em OUR) Va ae ie al ey be* a unig wie Green aad, Se y wii oe GA copy’ (ty hb? erp-enty, Table of Contents Abstract Dedication Preface Introduction Abiotic and Soil Investigations “Selected Climatic and Soil Thermal Characteristics of the Prudhoe Bay Region.’ Jerry Brown, Richard kK. Haugen, and Scott Parrish. “Observations on the Seasonal Snow Cover and Radiation Climate at Prudhoe Bay, Alaska during 1972.’’ Carl Benson, Robert Timmer, Bjorn Holmgren, Gunter Weller, and Scott Parrish. “Soil and Landform Associations at Prudhoe Bay, Alaska: A Soils Map of the Tundra Biome Area.’’ Kaye R. Everett. “Nutrient Regimes of Soils, Landscapes, Lakes and Streams, Prudhoe Bay, Alaska.’’ Lowell A. Douglas and Aytekin Bilgin. Plant Investigations “Vegetation Survey of the Prudhoe Bay Region.”’ Bonita J. Neiland and Jerome R. Hok. “V/egetation and Landscape Analysis at Prudhoe Bay, Alaska: A Vegetation Map of the Tundra Biome Study Area.’ Patrick J. Webber and Donald A. Walker. ‘Responses of Arctic, Boreal, and Alpine Biotypes in Reciprocal Transplants.” William W. Mitchell and Jay D. McKendrick. Animal Investigations “Ecology of Tundra Invertebrates at Prudhoe Bay, Alaska.’ Stephen F. MacLean, Jr. “Ecological Relationships of the Inland Tundra Avifauna near Prudhoe Bay, Alaska.’’ David W. Norton, Irvin W. Ailes, and James A. Curatolo. “Population Studies of Lemmings in the Coastal Tundra of Prudhoe Bay, Alaska.’ Dale D. Feist. “‘Notes on the Arctic Fox (A/opex /agopus) in the Prudhoe Bay Area of Alaska.” Larry S. Underwood. “Ecology of Caribou at Prudhoe Bay, Alaska.’’ Robert G. White, Brian R. Thomson, Terje Skogland, Steven J. Person, Donald E. Russell, Dan F. Holleman, and Jack R. Luick. Appendix A “Provisional Checklist to the Vascular, Bryophyte, and Lichen Flora of Prudhoe Bay, Alaska.” Barbara M. Murray and David F. Murray. Appendix B “Selected Data on Lichens, Mosses, and Vascular Plants on the Prudhoe Bay Tundra.”’ Michael E. Williams, Emanuel D. Rudolph, and Edmund A. Schofield. Plate | “Vegetation and Soils Maps, Tundra Biome Study Area, Prudhoe Bay, Alaska.”’ vii 113 125 13S 145 151 203 213 Inside Back Cover Preface This volume contains project reports on research sponsored and coordinated under the U. S. Tundra Biome Program of the Internation- al Biological Program (IBP) at Prudhoe Bay, Alaska. Comprehensive Biome research was initiated at Barrow in 1970. The Prudhoe Bay area was selected as a second arctic coastal plain site in order to gather comparative and validation data for the more comprehensive Barrow investiga- tions. In addition, the Prudhoe area was essen- tially unknown ecologically, and the program's presence in northern Alaska, with its large eco- logical research team, afforded an excellent op- portunity to gather data of a basic bioenviron- mental nature at Prudhoe. To this end, a series of studies ranging from one to three summers’ duration and reconnaissance observations were conducted in areas easily accessible from the road network. Funding of these Prudhoe research efforts has been largely shared amongst industry sources, the State of Alaska, and the National Science Foundation. Without exception, the logistical costs at Prudhoe were paid from funds provided by the Prudhoe Bay Environmental Subcommittee which, since 1970, have amount- ed to $282,000. Portions of these funds have been used to support direct research, and individual reports in this volume acknowledge their use. However, the magnitude of the Biome’s program at Prudhoe would not have been possible without the core-funded, National Science Foundation support of the 5-year Tundra Biome Program, a program jointly sup- ported at NSF by the Office of Polar Programs (OPP) and the International Biological Program (Ecosystems Analysis Section). This NSF pro- gram was largely funded for the Barrow inten- sive site which, in turn, provided personnel for the Prudhoe research. The Barrow and, sub- sequently, the Prudhoe projects were supported in the field by and provided with laboratory equipment from the Naval Arctic Research Laboratory at Barrow. Partial funding for the Prudhoe research has been derived from the State of Alaska and from nonrestrictive grants from individual oil companies to the University of Alaska’s Tundra Biome Center (Dr. George C. West, Director). The following is a list of con- tributing companies through 1974: Atlantic Richfield Company Alyeska Pipeline Service Company BP Alaska, Inc. Cities Service Company Exxon Company, USA (Humble Oil & Refining Company) Gulf Oil Corporation Marathon Oil Company Mobil Oil Corporation Prudhoe Bay Environmental Subcommittee Shell Oil Company Standard Oil Company of California Standard Oil (Indiana) Foundation, Inc. Sun Oil Company We wish to acknowledge the many individu- als and companies involved at Prudhoe who made the conduct of this program possible. The operators, BP Alaska, Inc. (Western Section) and Atlantic Richfield Company (Eastern Section), and their staff did everything possible to facili- tate the accomplishment of our projects. BP, and particularly Charlie Wark, lent considerable support in making lab and field space available and solving operational questions. Angus Gavin of Atlantic Richfield Company provided a con- siderable amount of background information on the birds and wildlife of the area as well as logistical assistance. The staff and facilities of Mukluk Freight Lines provided excellent work- ing and living conditions. Nabors Alaska Drilling Inc. provided additional field lab facilities. Both helicopter and fixed wing flights were provided by the operating companies, Alyeska, and others, and this assistance is gratefully acknowl- edged by all projects. The initial volume preparation was perform- ed at the U. S. Army Cold Regions Research and XI Engineering Laboratory under an interagency agreement with NSF for Tundra Biome manage- ment and publications. The CRREL editorial staff, Mr. Stephen Bowen, editor, and Mr. Harold Larsen, illustrator, is acknowledged for its early assistance in volume preparation. The final copy preparation, editing, and drafting was performed under the editorship of Ms. Laurie McNicholas and the graphics supervision of Ms. Mary Aho of the University of Alaska’s Arctic Environmental Information and Data Center (Mr. David Hickok, Director). Dr. Stephen F.MacLean, Jr. prepared the introduction and, along with Dr. West, provided considerable assistance in critical review and development of the volume. Barbara and David Murray provided verification of the usage of all plant names in the volume. Jerry Brown, Editor Geographical setting of the U.S. [BP Tundra Biome study area at Prudhoe Bay. CLIMATE Parasites ANIMALS Predators Herbivores VEGETATION Saprovores SOIL Decomposers LANDFORMS Radiation Precipitation Temperature Wind. Insects and Other Invertebrates Birds Mammals Mosquitoes, Warble flies, ———- _eVj7jai eo > etc. Sandel Owls, Fox, ene P Bers Jaegers Weasels Some adult Lemmings, WIGS: Waterfowl Sati leaf-hoppers; quirrels etc. Grasses, Sedges, Willows Beetles, Spiders Caribou (Dead Vegetation) g i tw _ ad 7 e+ @e4 oO ' ae cw a a} 7 ? — 409pe To ia 2 ae L é } - atta 4 : » vit ' 5 = ed F i w rf F i¢¢¢ peatamineti el a a a . e a | on “ile ; 5 _ 7 Sa ae ee — q 4 i! a wey ha o> iy ee alt wt pedo Gli airs 6 Sure ob Eginappe tee Carre cexiws! i by ary oy e Lalo), new ter ga ocleeg ae Ls Sly giver t wns = ey - | aii _ Pr ax ‘ eee e ka | a) g—~c ui lare a y {omee . te vod eae one deo rst ore cee fore ¥ 4 » © “ity jae >) OF ' ie ion a » pi ® i iv ae “< ot i @utltetind ; ew fiend a yh heii ctf % aTontat : gq =P Adee = 461. 6-2e ps y i ad rit ‘in - - a. diet unr at} ips hi Ave oun = ee o e . finde. »4 — io ere Abiotie and Soil Investigations Automatic, year-round weather station installed on a pingo at Prudhoe Bay. Data collected on strips charts included radiation, wind speed and direction, air and soil surface temperatures, and precipitation. The station was operated by the University of Alaska's Geophysical Institute. David Atwood, USACRREL Selected Climatie and Soil Thermal Characteristics of the Prudhoe Bay Region JERRY BROWN and RICHARD K. HAUGEN U. S. Army Cold Regions Research and Engineering Laboratory Hanover, New Hampshire 03755 SCOTT PARRISH* Tundra Biome Center University of Alaska Fairbanks, Alaska 99701 Introduction Biological, ecological, and environmental phenomena are dependent to a significant degree upon the air and soil thermal regimes. The climate of the Prudhoe Bay region was virtually unknown prior to 1969. The National Weather Service stations at Barrow and Barter Island provide the short- and long-term records from which to compare Prudhoe’s climatic position in the coastal plain. Based on previous analyses of North Slope air temperatures (Watson 1959; Searby and Hunter 1971), Prudhoe Bay should lie within the following temperature ranges: Mean maximum January between -20° and ZENG Mean minimum January between -27° and -30°C Mean maximum July less than +8°C Mean minimum July between 1° and 2°C Although a variety of standard climatic data have been obtained for the immediate Prudhoe Bay area over the past 4 to 5 years, air tempera- ture is emphasized in this report as this is the only parameter for which there are reasonably continuous and reliable records. Selected precip- itation, soil temperature, and thaw data are also “Deceased. presented to provide initial data for this relative- ly unknown region of the North Slope. The objectives of this report are: (1) To compare the limited air temperature and precip- itation records for Prudhoe Bay with a compar- able period for Barrow and Barter Island, (2) to examine annual and seasonal temperature varia- tions at Prudhoe Bay, (3) to characterize differ- ences in the temperature regimes of coastal and inland sites, and (4) to present limited soil temperature and thaw data. Methods Reasonably consistent climatic data are available from four principal sites (Fig. 1): (1) BP Alaska, Inc. radio station in the vicinity of the Mukluk Camp: This includes wind speed and direction and air temperature on a mast, recorded continuously. For the present report, daily minimum and maximum_ air temperatures were obtained from the original records. These records were made available by BP Alaska, Inc. and appear to offer the most consistent and continuous set of temperatures for the Prudhoe Bay area. The data from this site . Cas Fig. 1. Location of climatic and soil temperature stations. are referred to as Prudhoe (Mukluk) in this report; the location is about 8 km inland from Prudhoe Bay itself. (2) Prudhoe Airfield Tower: These data have been acquired by the Atlantic Richfield Com- pany since 1967, and observations have been essentially continuous since 1968. These data are not reported in the National Weather Serv- ice’s Alaska Climatic Data Summaries, although they are available from the National Climatic Center. In general, these data appear to be adequate for most purposes and probably com- pose the best record available by virtue of its length. A comparison of Prudhoe Tower data with data from Mukluk Camp is presented in Table 1 for 1970-1973. Averaged over this 4- year period, there is a difference of only 0.8°C in mean annual temperature for the two stations with Mukluk Camp being slightly colder. This difference could be actual. (3) Deadhorse Airfield: Data are hourly dur- ing the period of airfield operation, but are usually missing early morning observations. (4) Happy Valley Camp: This station is operated by Alyeska and has been reported to the National Climatic Center since 1970. It is also now listed in the Alaska Climatic Summary (National Weather Service), but data are often missing. This has been the only station recently in regular operation that is representative of the interior portion of the North Slope. Comparison of Prudhoe Bay air temperatures (°C). Table 1 Mukluk Camp Prudhoe Tower Mukluk Camp Prudhoe Tower Max Min Mean Max Min Mean Max Min Mean Max Min Mean 1970 1971 Jan -24.7 -30.5 -27.6 -28.5 -37.3 -32.9 -27.4 -36.8 -32.1 Feb -25.8 -32.2 -29.0 -24.7 -31.9 -28.3 -33.8 -40.3 -37.1 -33.5 -40.1 -36.8 Mar -25.9 -32.5 -29.2 -25.5 -32.4 -29.0 -25.7 -33.7 -29.7 -24.9 -32.6 -28.7 Apr -15.1 -22.1 -18.6 -15.2 -21.9 -18.6 -16.6 -26.8 -21.7 -17.3 -26.8 -21.7 May -4.7 -9.8 =i -3.2 -9.6 -6.4 -3.9 -9.8 -6.8 -3.7 -9.6 -6.7 June 5.0 -0.9 24 5.2 -0.4 Pees 7.4 0.7 4.1 74 1.4 44 July Cy 1.6 5.4 8.4 2.0 5.2 113 3.1 Te iS 3.9 ZA. Aug 7.9 1.8 48 7.8 ZS 5A 5.8 -0.5 2f 6.1 0.6 as Sept 0.4 -5.4 -2.5 -0.1 49 -2.5 Tok -2.7 -0.5 2.3 -1.6 0.5 Oct -13.9 -20.5 -17.2 -14.7 -20.2 -17.4 -9.4 -17.9 -13.6 -8.0 -15.9 -11.9 Nov -15.4 -23.6 -19.5 -15.2 -23.7 -19.4 -17.2 -24.2 -20.7 -16.7 -23.2 -19.9 Dec -23.6 -31.5 -27.6 -22.7 -30.5 -26.6 -25.6 -31.4 -28.4 -25.7 -29.4 -27.6 Annual means -10.4 -16.8 -13.6 -11.2 -18.4 -14.8 -10.8 -17.5 -14.2 1972 1973 Jan -26.3 -32.6 -29.4 -26.4 -31.2 -28.8 -22.6 -31.3 -26.9 -24.4 -29.1 -26.7 Feb -29.2 -32.6 -32.2 -29.1 -34.8 -31.9 -25.1 -32.3 -28.7 -25.3 -30.3 -27.8 Mar -28.3 -34.7 -31.5 -28.2 -34.1 -31.1 -29.9 -37.4 -33.7 -29.5 -35.9 -32.7 Apr -16.7 -26.3 -21.5 -15.7 -24.3 -20.1 -13.7 -24.4 -19.1 -13.8 -22.3 -18.0 May -3.9 -10.7 -7.3 -2.9 -8.6 -5.8 -2.5 -8.4 -5.4 -2.2 -7.1 -47 June 4.7 -0.3 2:2 4.6 0.9 21 4.5 -0.1 22 4.3 0.9 2.6 July 10.6 ZA 6.3 10.1 4.0 ZA ATA 2.4 6.8 11.2 4.8 8.0 Aug 9.2 2.3 5. 9.4 3.6 6.5 9.8 3.1 6.4 9.7 4.6 V2 Sept 0.4 -3.9 -1.8 0.9 -1.2 -0.7 4.5 -1.2 tier 4.8 0.4 2.6 Oct -4.6 -12.6 -8.6 4.8 -9.8 7.3 -7.2 -13.7 -10.4 -7.1 -11.1 -9.1 Nov -15.9 -20.9 -18.4 -15.7 -19.3 -17.6 -14.3 -20.6 -17.4 -15.3 -18.8 -17.1 Dec -19.0 -26.4 -22.7 -19.8 -24.6 -22.0 -19.3 -25.9 -22.6 -19.9 -23.8 -21.9 Annual means -9.9 -16.7 -13.3 -9.8 -15.1 -12.4 -8.7 -15.8 -12.3 -8.9 -14.0 -11.4 In addition to these sites, the Tundra Biome established several locations of various duration. In order to establish the magnitude of the spring and summer temperature gradient from the coast inland, recording thermographs in standard shelters were deployed in 1972 and 1973 at Point McIntyre and on a terrace along the Sagavanirktok River approximately 16 km south of the Deadhorse Airfield. An automatic, bat- tery operated weather station was installed in the Biome study area on the pingo east of the Putuliagayuk River and operated intermittently between 1971 and 1973. The 1971 precipitation data are from a lake adjacent to the Biome study area (Kane and Carlson 1973). Other projects have collected climatic data in the Prudhoe Bay area, notably the Gas Arctic project located across from the Mukluk Camp. Casual compari- sons of these data have been made but are not discussed in the report. Table 2 Mean monthly and annual temperatures (°C) for Barrow, Prudhoe, and Barter Island (1970-1973) * 1973 Barter Barrow Prudhoe Island Barrow Jan -25.3 -26.9 -24.6 -26.8 Feb -25.1 -28.7 -26.9 -28.4 Mar -29.3 -33.7 -31.6 -28.7 Apr -19.3 -19.1 -18.8 -20.2 May -7.2 -5.4 -5.4 -7.7 June 0.7 De 1:2 0.3 July 4.3 6.8 4.9 6.1 Aug 4.3 6.4 4.3 4.8 Sept 11s | (e7/ 17 -0.4 Oct -7.0 -10.4 -9.0 -6.1 Nov -13.4 -17.4 -16.4 -17.0 Dec. -20.8 -22.6 Bal |e -19.3 Annual -11.4 -12.3 -11.8 -11.9 1970 Barter Barrow Prudhoe Island Barrow Jan -24.7 -27.6 -26.5 -26.3 Feb -27.2 -29.0 -27.3 -28.2 Mar -28.0 -29.2 -28.5 -28.5 Apr -19.4 -18.6 -18.1 -19.8 May -7.2 -7.2 -6.7 -7.6 June 0.5 2.1 0.8 0.8 July 32. 5.4 3.8 4.6 Aug Tez -4.8 4.7 29 Sept -3.5 -2.5 -2.8 -0.8 Oct -17.5 -17.2 -16.2 -10.1 Nov -20.1 -19.5 -18.2 -17.2 Dec -23.4 -27.6 -26.0 -21.8 Annual -13.8 -13.9 -13.4 -12.7 1970-1973 Mean 1972 1971 Barter Barter Prudhoe Island Barrow Prudhoe Island -29.4 -26.9 -28.6 -32.9 -30.4 32.4 28.8 -32.3 SEA -34.6 87) |) 28.5 -27.9 29.7 28.4 215 20.3 -20.3 21.7 213 Th) Flee} -8.1 6.8 6.5 22 Ae2 TZ 4.1 2if 6.3 4.1 4.7 Le 6.1 5.7 5.2 0.8 27 2.0 1.8 0.9 0.2 0.5 0.8 8.6 6.3 -9.9 -13.6 11.4 18.4 ies -18.1 20.7 17.4 22ef 20.4 -24.1 28.4 24.6 13:3 12.2 -13.5 14.8 13.7 (1941-1970) 30-Year Normals Barter Barter Prudhoe Island Barrow Island -29.2 -27.1 -25.9 -26.2 -31.8 -29.4 -28.1 -28.6 31.0 29.2 -26.2 25.9 20.2 19.6 -18.3 TL 6.7 -6.5 7.2 6.1 2.6 1.4 0.6 12 6.4 4.7 3.7 4.4 4.8 4.1 ot 3.8 0.8 0.7 -0.9 0.2 12.5 10.7 9.3 8.7 19.0 173 -18.1 VIET. 25:3 Zac -24.6 24.7 -13.6 -12.8 -12.6 -12.2 *Source: Barrow and Barter Island: National Weather Service. Prudhoe Bay: BP Alaska, Inc. Mukluk site with several intervals of missing data filled in with Prudhoe tower data. Freeze-thaw degree-day indices were com- puted by the standard technique of summing the daily departure from O°C. Progression of season- al soil thaw was determined by Bilgin (1975) for the summer of 1972 using a probing technique. Soil temperatures were also recorded in 1972 on Grant recorders for a polygon area north of Pad F, and the data reduced at 3-hour intervals. Results Table 2 presents the mean monthly and annual temperature data for Barrow, Prudhoe, and Barter Island. Prudhoe clearly has warmer summers and colder winters than either Barrow or Barter Island. The effect of continentality only a few kilometers inland from the ocean is exemplified by the Prudhoe data and, as will be shown, the effect becomes rapidly more pronounced further inland. As shown in Table 2, the annual temperature regimes at Prudhoe paralleled those of Barrow and Barter Island in terms of individual warm and cold seasons as well as annual averages. Annual averages for both 1970 and 1971 were cooler than 1972 and 1973 across the entire coastal plain. The variations from year to year of Prudhoe temperatures are further demonstrated Table 3 Maximum and minimum monthly temperatures (°C) for January and July at Prudhoe (1970-1973) January July Year Max. Min. Max. Min. 1973 -22.6 =Sile3 11.1 2.4 1972 -26.3 -32.6 10.6 2.1 1971 -28.5 -37.3 Wiles: Sal 1970 -24.7 -30.5 9.2 1.6 in Table 3, based on January and July mean monthly maximum and minimum values. It is observed in Table 4 that the most notable differences between the coastal stations, Barrow and Barter Island, and the inland sta- tions, Prudhoe and Happy Valley, are in the summer warmth. Even comparing the coolest summers at the inland stations with the warmest summers of the coastal stations, the summer degree-day accumulations for the interior sta- tions are consistently greater. The coldest win- ters at Barrow, on the other hand, can be as cold as or even colder than the inland stations. This is undoubtedly due to the presence of the ice cover which, in effect, creates a more continen- tal climatic situation for the coastal stations during the winter. Barrow Point McIntyre Barter Island Prudhoe 16 km south Happy Valley Barrow Point McIntyre Barter Island Prudhoe Happy Valley Table 4 Comparison of mean monthly temperatures and thawing degree-days (°C) at coastal and inland stations. Mean Monthly Temperatures and Thaw Degree-Days June July Aug Total Thaw Degree-Days 1972 0.3 (9) 6.1 (189) 4.8 (148) 346 0.3 (9) 3.9 (120) 4.6 (142) 271 1.2 (36) 4.1 (127) 5.2 (161) 324 2.7 (81) 6.3 (195) 5.7 (176) 452 2.5 (75) 7.3 (226) 6.5 (201) 502 8.1 (243) 12.6 (390) 9.8 (303) 936 1973 0.7 (21) 4.3 (133) 4.3 (133) 286 O7A(2iio) 4.5 (139) 4.6 (133) 254 1.2 (36) 4.9 (151) 4.3 (133) 320 2.2 (66) 6.8 (210) 6.4 (198) 474 8.7 (261) 12.2 (378) 7.5 (232) 871 *Partial months (12-30 June; 1-24 August) At Prudhoe, the mean maximum values for July in excess of 10°C are significantly greater than would have been estimated using only data from the immediate coastal stations at Barrow and Barter Island. The steepness of the summer temperature gradient from the Arctic coastline inland is illustrated in Table 5. Summer data from two stations, Point McIntyre on the coast and a location approximately 16 km south of Dead- horse, are incorporated to provide continuity. Considering a total distance of approximately 144 km from Point McIntyre south to Happy Valley, the increase of total thaw season degree- days is 5 degree (°C) days per kilometer proceeding inland. The temperature gradient may also be characterized by July temperature differences. Based on the data given in Table 4, an average increase of July mean temperature away from the coast is 5.9°C (100 km)'. Some comparable data are available inland of Barrow. Temperature data obtained in 1966 by Johnson and Kelley at Meade River, 120 km south of Barrow, showed a 6.5°C difference from Barrow (North Meadow Lake) temperatures for the month of July. This gives an inland temperature increase of 5.4°C (100 km)', almost identical to the rate determined for the Point MclIntyre- Happy Valley gradient. Also based on the Meade River data, a total thaw season degree-day gradi- ent of 3.9°C km’! was calculated, about one degree C less than indicated for the Point McIntyre-Happy Valley gradient. Climatic gradi- ents have also been observed from Barrow south- ward by Clebsch and Shanks (1968). Increases for rainfall, evaporation, and evapotranspiration were observed between Barrow and their study site 55 km inland. Temperature observations were limited to weekly maximum and minimum values in that study, and are not directly com- parable to the above analysis. All of the other Table 5 Annual thaw/freeze degree-day (°C) accumulations 1970-1973 Summer 1970/ Winter 1970-71 Summer 1971/ Winter 1971-72 295/4891 Summer 1972/ Winter 1972-73 320/4496 273/5417 Barrow Barter Island 372/5520 352/5063 402/4585 Prudhoe 529/5739 564/5469 617/4835 Happy Valley 890/5331 1020/5081 956/5372 Degree-days (°C) 4 4 so 4 == L “+ 4 n Mi-eAG, (Min TUDE TU, AS aa OMLIN amb aaa Month Fig. 2. Freeze-thaw regimes for principal North Slope stations. parameters measured, however, clearly indicated increased warmth and moisture gradients toward the inland study site. These are important gradi- ents for many types of environmental phenome- na and should be considered in any study uti- lizing coastal temperature data to represent con- ditions some distance from the coast. Fig. 2 illustrates the annual freeze-thaw regimes for the principal North Slope stations for the period of similar record. The similarity of the freeze season, the increased warmth, and greater temperature amplitude of inland loca- tions discussed above can be observed. Precipitation It is difficult to assess the variation of precipitation regimes as was done with air tem- peratures because precipitation values show greater fluctuations and were not obtained at all stations. The only long-term records, Barrow and Barter Island, indicate that Barter Island receives considerably more summer precipitation than Barrow (Table 6). The only available sum- mer precipitation data for Prudhoe Bay are from 1971 (Kane and Carlson) since Biome observa- tions were considered anomolous. The monthly totals are low compared to other stations on the North Slope. Summer precipitation amounts appear to increase inland as evidenced by partial records for Happy Valley, and as previously indicated by Clebsch and Shanks (1968) for the Barrow area. Soil thaw In 1972 Bilgin (1975) measured the progres- sion of soil thaw at 14 different sites. Soils varied in texture, organic content, moisture, slope and resulting vegetative cover. The range in maximum soil thaw by late August was between 25 cm in wet organic soil and 90 cm in the dry sandy upland soils. Fig. 3 contains plots of thaw progression in four distinct soil conditions. This range in soil thaw over relatively small distances is common for northern Alaska and has been reported for a detailed transect in the Barrow area (Brown 1969). Soil Temperature Soil temperatures as influenced by polygon microrelief were recorded at six locations at 3-hr intervals during summer 1972. The sites were located within a 15-m radius with duplicate sites selected in a polygon trough, on a polygon rim, and in a polygon center. Fig. 4 is an idealized cross-section and plan view of the site. Fig. 5 contains the daily mean values for each of the three microrelief positions at 1, 5, and 10 cm depths and the Prudhoe air tempera- ture record. The July and August 1972 mean daily tem- peratures in the upper 1 to 10cm soil were Sandy Upland Tundra 80 (cm) Sandy Dry Meadow Tundra (op) {e) Silty Dry Meadow Tundra 40 Dry Phase Organic Soil Depth of Thaw 20 20 10 20 Aug (Sire Fig. 3. Seasonal progression of thaw for four Prudhoe Bay soils (Bilgin 1975). Table 6 Comparison of 1971 precipitation data (mm) June (13-30 June) July August September Barrow trace 24.9 8.9 4.3 Barter Island 2.0 76:5) 1027, 23.1 Prudhoe Bay (near Pingo Site) 2:5 20.3 16.5 6.9 Happy Valley 5uilie 50.8 20.1 = “Value wholly or partially estimated. Fig. 4. /dealized cross-section and plan view of polygon microrelief for soil temperature measurements. within the range of 2° to 12.5°C. The maximum daily mean temperatures at 10 cm were below 8°C. The extremes in mean daily temperatures were encountered in the polygon trough with core 3 being the coolest (2° to 6.5°C) and core 6 the warmest (3.5° to 12.5°C). These differ- ences are undoubtedly due to local microrelief and soil properties. Temperatures at these shal- low soil depths closely reflected daily air tem- peratures. Since gravel pads and roads cover a signifi- cant portion of the Prudhoe landscape, it is important to know how they influence near- surface temperature and thaw regimes. Tempera- tures of gravel surfaces as compared to air 10 f ao Air 412 + 416 t 4 L 44 - 4 f 12 4 4 1 4 2 4 1—___J 20 10 20 10 20 Jun Jul Aug = = T T a T T T T T = tf b Trough ; AA ne Bt l2 \ IF MRO AVA \ aN ENN Ve, M N uv ‘ Fig. 5. temperatures in a standard shelter were obtained by the authors in 1974. Gravel temperatures within a centimeter of the bare surface were recorded between 19 July and 3 September 1974 on pad F. During this period the mean air temperature was 7.0°C, and the mean surface temperature of gravel was 9.2° C. Regression of daily average surface and air temperatures yield- ed the equation Y = 3.60 + 0.785X where Y is the average daily surface temperature and X is the average daily air temperature. The correla- tion coefficient (r) for this relationship is 0.90. Based on this analysis, an air-gravel surface temperature relationship is defined. The regres- sion equation can be applied to Prudhoe summer air temperature data as input to thawing and freezing computations and modeling. Conclusions It is apparent that the area adjacent to the road net at Prudhoe can be characterized as an 2G Temperature Daily mean temperature values for air and microrelief positions at 1,5, and 10 cm depths. inland coastal climate and is significantly differ- ent than the immediate coastal climate as char- acterized by Barrow, Barter Island, and the summer temperature record at Point McIntyre. The shift to a true continental temperature regime occurs only a few kilometers inland of the coastline during the summer, although the winter ice cover off the coast reduces tempera- ture differences during the freezing season and provides a near-continental temperature pattern even to the coastal stations. Acknowledgments A large number of people have assisted in the acquisition and processing of these data. Helicopter time was provided by both Alyeska and Atlantic Richfield in servicing the remote stations at Prudhoe Bay. Robert Timmer assisted in servicing these stations in 1972. Funds from the Prudhoe Bay Environmental Subcommittee and BP Alaska, Inc. to the University of Alaska were utilized by Scott Parrish and others in- volved in the field work. National Science Foun- dation and Corps of Engineers funding to USA CRREL were employed by the senior authors. Martha Greer and Carolyn Merry of CRREL assisted in processing the air temperature data. Soil temperature data were acquired and reduced by Dr. Stephen MacLean, University of Alaska, and computer processed by Cecil Good- win, University of Michigan. References Bilgin, A. (1975). Nutrient status of surface waters as related to soils and other environ- mental factors in a tundra ecosystem. Ph.D. dissertation. Rutgers University, New Bruns- wick, N. J., 201 pp. Brown, J. (1969). Soil properties developed in the complex tundra relief of northern Alas- ka, Biul. Peryglacjalny 18:153-167. Clebsch, E. E. C. and R. E. Shanks (1968). Sum- mer climatic gradients and vegetation near Barrow, Alaska, Arctic 21:161-171. Kane, D. L. and R. F. Carlson (1973). Hydrol- ogy of the Central Arctic river basins of Alaska. Institute of Water Resources, Univer- sity of Alaska, Report No. IWR-41, 51 pp. Johnson, P. L. and J.J. Kelley, Jr. (1966). Results and reprints of ecological investiga- tions, Meade River, Alaska (summer 1966). USA CRREL Internal Report 467. Searby, H. W. and M. Hunter (1971). Climate of the North Slope, Alaska. NOAA Technical Memorandum AR-4, Anchorage, Alaska. Watson, C.E. (1959). Climates of the State, Alaska. Climatography of the United States No. 60-49. U. S. Department of Commerce, 24 pp. WZ Mosaic of three ERTS images of the Colville River area obtained on 27 May 1973. The Prudhoe Bay road system can be clearly seen to the west of the open Sagavanirktok River at the upper right corner. NASA Contract NAS5-21833, Task 4 Observations on the Seasonal Snow Cover and Radiation Climate at Prudhoe Bay, Alaska during 1972 CARL BENSON, BJORN HOLMGREN*, ROBERT TIMMER**, and GUNTER WELLER Geophysical Institute University of Alaska Fairbanks, Alaska 99701 SCOTT PARRISH*** Tundra Biome Center University of Alaska Fairbanks, Alaska 99701 Introduction The snow structure on the Arctic Slope in general consists of a hard, high density, fine- grained, wind packed layer, overlying a coarse, low density, depth hoar layer; it resembles the top annual stratigraphic unit of the perennial dry snow facies of the Greenland or Antarctic ice sheets. It differs markedly from the snow of interior Alaska between the Brooks Range and Alaska Range. The latter is characterized by low density, steep temperature gradients, and a thick basal depth hoar layer which sometimes makes up two-thirds or more of the snow pack. Measurements on the 1971-1972 seasonal snow cover at Prudhoe Bay were made during September 1971 and, most extensively, in the spring of 1972. Some supplementary measure- ments were also made at Prudhoe Bay during the spring of 1973. The Prudhoe Bay observations were made in the context of long-term observa- tions on physical properties of Alaskan snow cover which began in 1961. However, they focused on specific problems in the Prudhoe Bay area which result from industrial activities. Fig. 1 shows the location of traverses and sample sites in the Prudhoe Bay area. An attempt was made to determine the amount of snow on the ground and to define the nature of the drift patterns caused by wind. The water equivalent of the snow was determined from measurements of its depth and density. Snow temperature and density profiles were measured together with characteristics such as hardness and grain size, a general stratigraphic description of the snowpack and the type of base (i.e., grass, ice, gravel, etc.) The amount of dust and coarser sediment contained in the snow was determined by melting and filtering snow samples. The electrical conductance of the melt water from these sarnples was also measured. The sources of the sediments were bare ground areas in and adjacent to the Sagavanirktok River channels and the road network. An attempt was made to determine the effect of dust on snow melt rate. The distribution of snow by wind drifting is an impressive feature about the Arctic Slope in general. The winds which cause the drifting are “Current address: Meteorologiska Institutionen, Observatone Parken, Uppsala, Sweden. **Current address: University of New Mexico, Albuquerque, New Mexico 87131. *** Deceased. 14 “Ajaniqvadsas ‘G-1 sease se/NBUeJIAS Us uaye] asam ‘jjauumMous 40 ssa4Bosd ay2 MOYS YIIYM ‘1 Z-Z1 $a4nBi4 ul sozoyd Jenuanbas ay | ‘saz/s ajduies pue assanesy YyiIM ease Aeg aoypnig so dey) *| “614 Ip 144) bE SejdwoS mous FO, -pieitsiy v Joypo eq JEQWNN YIIM JAaxJDW QUIT aqGOlg bde J8QWNN YsIM UOIyD907 ajdwoS MoUs JI o 9 ON 9su9ADI, QL GN3931 a one \ fo] « 26 !01 OO! Playsiy 4. Aog soypnig £3 = ES (S 61; eas) saipnys MOUS peji0jeq @sJandd) UONDIPDY ausOquIy Aog e0ypnig | i C CLI 0 JQ 2917. 6ld \ MS remarkably constant in direction. Two direc- tions are important: (a) storm winds, which bring new snow, are generally from the west and (b) prevailing winds, which primarily serve to redistribute snow on the ground, are from the east. The two aircraft runways in the Prudhoe Bay area are aligned with the prevailing winds. Also, the lakes in this region have a pronounced tendency to become elongated in a direction perpendicular to the prevailing winds; an expla- nation of this was provided by Carson and Hussey (1962). West winds are slightly more important for snow drifting in the Prudhoe Bay area, while the east winds are more important for moving dust. Because of drifting, the snow thickness varies from almost nothing up to 2m in this region. Before discussing such variations, it will be useful for us to discuss the techniques of measurement and, in the next section, to consider the physical characteristics of the snow and some of the processes involved in_ its melting. Three methods of measurement were used to observe the snow itself: 1. Pit studies: Standard snow stratigraphy studies as used in Greenland and parts of Arctic Alaska (Benson 1962, 1967, and 1969) were used to make detailed studies of the snowpack (Figs. 7 and 9). Thermometers and density sample tubes (500 cm? volume) were inserted horizontally into the exposed pit wall (Fig. 7). The samples were taken in such a way that density values could be calculated for each layer. The layers were plotted with sharp boundaries to indicate the stratified nature of the snow. 2. Vertical cores: A large number of verti- cal cores were made by driving an aluminum tube, sharpened on one end, through the entire snowpack. Snow was removed from around the tube, a metal plate was inserted at the base, and the contents were placed into a plastic bag for measurements of average snow density, dust content, and electrical conductance of the derived meltwater. Before emptying the con- tents into the bag, the base of the sample was examined and any loose soil or grass was re- moved; if this material could not be removed another sample was taken. This sampling tech- nique was used on all of the traverses and dust collection sites. It has the advantage of sampling Fig. 2. Fig. 3. 15 Photo of snow, 6 September 1977. Pes Photo of snow, 13 April 1972. 16 Sa Fig. 4. Contrast between depth hoar crystals and overlying fine-grained snow. Road 9b P2 . Fig. 5. Sketch map of test area near pingo and PZ the entire snowpack including any ice lenses that may be in it, as referred to below. 3. Snow probing: In addition to the above measurements, which yield information on physical characteristics of the snow, a snow probing method was used extensively to deter- mine snow depth along nine selected traverses (Fig. 1). The probing was done with a steel rod, graduated in centimeters, which was poked through the snow at 2 m intervals several times during May and early June. This technique provides a rapid means of measuring snowdrift distributions. Physical Characteristics of the Snow General features The snow cover formed at Prudhoe Bay before the first of September in 1971. An example of its appearance, exposed in a shallow pit on 6 September, is shown in Fig. 2. In this place the snow was only 13 cm deep, coarse and wet at the bottom, with an icy crust 2-3 cm above the base. Some complexity already was apparent, especially in contact with clumps of vegetation. In some places the snow depth did not increase much during the entire winter, as shown in the photograph (Fig. 3) taken near Barrow on 13 April 1972. In this example the snow depth varied from 10 to 17 cm, the bottom tempera- ture was -13°C, and the coarse crystalline depth hoar layer at the base of the snow varied in thickness from 1 to 5 cm. In places where the snow is more than 40 cm deep, the basal depth hoar layer may be 20 cm thick. (In interior Alaska the entire snowpack may be predomi- nantly depth hoar.) The contrast between depth hoar crystals from the base of the snowpack and the finer grained material from the top is illus- trated in Fig. 4. Depth hoar crystals with dimen- sions of 1cm are common, but grains in the fine-grained snow are generally less than 1 mm diameter. Between these extremes is a medium- grained (1-2 mm) snow which is generally inter- mediate in grain size, hardness and density. The fine-grained snow is often wind packed and hard—frequently called a wind slab. Another extreme case, the most unstable of all, is fresh new snow which is usually transformed rather quickly into one of the other types. In summary, the stratigraphy of snow on the Arctic Slope can generally be described by refer- ring to only four major varieties of snow. In approximate order from top to bottom in the snow pack these are: Range of Range of Grain size density Snow type (mm) (g cm-3)* = . Fresh new snow, variable 0.5 to 1.0 0.15 to 0.20 crystal forms sometimes <0.5 2. Wind slab, hard, fine- 0.5 to 1.0 0.35 to 0.45 grained 3. Medium-grained snow 1to2 0.23 to 0.35 4. Depth hoar, coarse 5 to 10 0.20 to 0.30 loosely-bonded crystals Spring thaw Some case examples of the snow structure measured during the spring near the Tundra Biome pingo site at Prudhoe Bay (Figs. 1 and 5) will be discussed. Figs. 6a and 6b shows the pingo, with the automatic recording weather station on top of it, during fall and spring. The photograph of early fall snow structure shown in Fig. 2 was taken at the time and place when the photograph in Fig. 6a was taken (6 September 1971). A typical example of the snow structure on the tundra during spring, prior to melting (Table 1), is shown in Fig. 7; this profile was measured 350 m NE of P-2 (Fig. 5) on 14 April 1972 (Fig. 7). Three layers were easily distinguished by brushing the side of the pit to reveal differences in resistance to abrasion. They show up clearly in the photograph and in the density and strati- graphy data which are plotted below it; they may be briefly summarized as follows: 1. Top—fine-grained (0.5-1.0 mm), wind pack- ed, density = 0.36 gcm°?. 2. Middle—medium-grained (1-2 mm), density = 0.26 gcm*. 3. Bottom—coarse-grained, depth hoar crystals (5-10 mm), density = 0.19 gcm’s. The total water equivalent of the snowpack in this example was 12.5 cm H>O as determined by integrating the depth-density profile; the amount of heat required to raise its temperature 17 Fig. 6a. Pingo, 6 September 1977. Fig. 6b. Pingo, 14 April 1972. “The density ranges are only approximate and indicate the differences one may expect between these snow types. 18 to the melting point was 102 cal cm? (Table 2). After raising its temperature to O°C, another 1,000 cal cm’? would be required to melt it. However, the actual melt process is complicated by localized percolation and refreezing of melt- water in the snow after slight melting occurs on the snow surface. This percolating water re- freezes to form a complex network of ice glands (nearly vertical, pipelike structures) and ice lenses throughout the snow and at the tundra- snow interface. The process is analogous to the formation of superimposed ice on glaciers (Trabant, Fahl, and Benson 1975). These masses of ice within the tundra snow may remain for several weeks and may significantly modify the snowpack as a habitat for small animals such as lemmings, which live under the snow, or large animals such as caribou, which feed by breaking through it. The 1972 spring provided an excel- lent example of the process involved in forming these ice masses in the snow. The snow was subjected to slight surface melting on 6-7 May when the maximum air temperature was above freezing. After 7 May the maximum air tempera- ture remained below freezing until 27 May, as summarized in Table | and Fig. 8. Figs. 9a, 9b, and 9c show snow profiles* measured along a traverse line east from P-2 (Fig. 5) on 14 May. The pit study plotted in Fig. 9a, made only 8m east of the road, is in the drifted snow alongside the roadbank. The pit studies in Figs. 9b and Qc are far enough from the road to be essentially unaffected by it; the same is true of the profiles in Figs. 9d and Ye, which were measured on 16 May. A deposit of fresh new snow appears at the top of each of these profiles. It was deposited between 11-13 May and overlies the surface melt crust pro- duced on 6-7 May. In addition to the melt crust which formed on the snow surface of 6-7 May, there were ice glands, lenses, and layers in the snow. These are shown in black in the strati- graphic columns of Figs. 7 and 9. The location of these ice lenses at the base of a fine-grained layer is common. They also form in such strati- graphic locations in the deep snow of glaciers. In Temp.°C Density, g cm? -20 -10 ie) 0.25 0.20 0.30 0.40 Depth, cm Ap AR 0 " Fig. 7. Combined photo and data plot, 200m east of pingo, 14 April 1972. the examples shown here, they are most com- monly at the top of the depth hoar layer. Later in the melt season ice layers form at the base of the depth hoar layer; at Prudhoe Bay in 1972 this did not occur until the end of May and during the first week of June. Similar timing for the formation of ice masses at the base of the snow was observed at Barrow and Prudhoe Bay during the spring of 1973. “Unfortunately, a Rammsonde penetrometer was not available during these measurements. Typical Rammsonde profiles in tundra snow are available (Benson 1969), and a detailed study of the snow at Barrow using Ram hardness profiles was carried out during the 1972-1973 winter by Melchior and Benson. Table 1 Prudhoe Bay, Alaska, maximum and minimum temperatures °C May 1972 (See Fig. 8) Date Maximum Minimum 1 - 6.1 -16.1 2 1 -14.4 3 10.0 -17.8 4 - 7.8 -16.7 s) 0.6 -14.4 6 1.7 - 6.1 z 20 - 12 8 - 0.6 - 5.6 9 “del -12.2 10 - 5.6 -16.7 11 5.0 -15.6 12 - 3.3 12.2 1S - 3.9 SER 14 = bY -13.3 15 -10.6 -15.6 16 10.6 20.0 V7 -11.1 16.1 18 SORRY! -18.9 19 -10.6 15.6 20 = 3:9 14.4 21 72 12.8 22 - 3.9 15.6 23 - 3.9 TAS7. 24 28 10.0 25 - 17 - 9.4 26 = 22 - 7.8 27 1.1 - 6.7 28 5.6 So 29 1.1 edd 30 0 2.2 31 0.6 Ss The snow temperature profiles in Fig. 9 contain information on processes operating in the snow. In Figs. 9b and 9c the temperature decreases from -3+1°C at the snow surface to about -10°C at the bottom. However, we know that the surface temperature was at O°C during 6-7 May because of the melt crust and the evidence of percolation and_ refreez- ing of meltwater in the snow. These profiles also have anomalously high temperatures adjacent to the ice lenses in the snow. These temperature anomalies, caused by the release of latent heat as percolating meltwater refroze to form the ice lenses, have already been smoothed consider- ably. Initially, they can be quite pronounced, as has been seen in polar glaciers (Benson 1962, pp. 22-23 and Fig. 25). The amount of percolating meltwater in these examples may be estimated from the thickness of the ice lenses and the increase in density involved in forming them. The total amount of ice in the stratigraphic columns was about 1 cm, varying from 0.5 to 2 cm. Most of the ice lenses occurred at the base of or within the fine-grained hard layer. The increase in density was in the range of 0.5 to 0.6 gcm’*. Thus, in these cases the amount of latent heat added at the surface but released at depth within the snow was about 40 to 50 cal cm. This is a significant part of the total amount of heat which was required on 14 April to bring the snow to the melting point. During the time when the percolation process operates, the tundra snow cover may undergo significant daily temperature variations in addition to the longer sort of variations summarized in Table 1 and Fig. 8. Indeed, the tundra snow is so shallow that temperature variations imposed at the surface are transmitted rapidly to the bottom even without the action of percolating meltwater. This is especially clear when one compares the temperature profiles of Figs. 9b and 9c with those of Figs. 9d and Ye, which were measured only 2 days later. The system remained below the melting point during this time, so there was no latent heat transfer by percolation and refreezing. To facilitate the comparison, we have plotted five of the temper- ature profiles* from Figs. 7 and 9 on a single diagram (Fig. 10). The mid-May cooling trend is clearly apparent. Indeed, the amount of heat required to raise the snow to its melting point (the “cold content’’), was only 34 cal cm? in both Figs. 9b and 9c. Two days later, on 16 May, it had increased to 63 cal cm*? (Fig. 9d). It was 87 cal cm in Fig. 9e, but that profile has a slightly larger mass. The water equivalent of the snow, profiled in Figs. 7 and 9, and its cold content are summarized in Table 2. “The profile in Fig. 9a was omitted because the depth was anomalous. 20 It is instructive to attempt to calculate temperature variations and heat exchange in the snow which result from the daily energy fluxes at the surface. Difficulties lie in the uncertain values for the thermal diffusivity of tundra snow and the fact that air convection may play a significant role in the snow (Trabant and Benson 1972). Published thermal diffusivity values for snow vary widely. This is mainly because of the variability in snow itself; it is reasonable to expect variations in diffusivity values by a factor of 2 or more in a typical tundra snowpack. A useful summary of thermal data for snow was provided by Hansen (1951), and from it we find diffusivity values suitable for tundra snow rang- ing between 0.0030 and 0.0050 cm? sec’!. However, Sorge (1935) found a higher range of value for the packed snow of the Greenland Ice Sheet. His values would be especially appro- priate for the wind packed layers on the tundra. Thus, it is reasonable for us to use the range from 0.0030 to 0.0060 cm? sec’'. Table 2 Water equivalent and “‘cold content’’ summary of data plotted in Figs. 7 and 9. The water equivalent is calculated by integrating the depth-density profile. The ‘cold content” is a measure of the amount of heat required to raise the snow to the melting point. A general summary of the data is as follows: Reference Total depth Fig. 7 47 Fig. 9a i 7/ Fig. 9b 36.5 Fig. 9c 35 Fig. 9d 42 Fig. 9e 46 Average Density gcm3 0.266 0.345 0.329 0.307 0.285 0.324 The detailed summary of each profile is tabulated below with the columns labeled as follows: h = height above soil surface Ah = height interval p = snow density AWE = water equivalent of height interval, Ah DWE = cumulative water equivalent of snow from bottom to height Ah (Note the units of AWE and DWE can also be thought of as the height of a column of water, i.e., (cm HO) c = Specific heat of ice AT = Difference between measured snow temperature and 0°C AO = Heat required to raise the temperature of the given increment of snow to OG: AQ= (AWE) xcx AT DO = Sum of AQ values Total Water Total Cold Equivalent Content cm HzO cal cm“? 12.51 102 40.45 161 12.03 34 10.75 34 11.97 63 14.92 87 (cm) (cm) (gcm) (g cm?) (gem?) (cal g! ca ) (°C) (cal cm 2) (cal cm?) Table 2 continued h Ah p AWE DWE c AT 14 April 1972 350m NE of P2, near Pingo (Fig. 7) 0-17 17 0.19 S25 3.23 5 17 17-33 16 0.265 4.24 747 sl) 16.2 33-47 14 0.36 5.04 12.51 5 16 14 May 1972 28m E of P-2 (Fig. 9a) 00-9 9 0.275 2.48 2.48 5 12 9-19 10 0.340 3.40 5.88 5 11.5 19-30 11 0.365 4.02 9.90 5 10.5 30-38 8 0.322 2.58 12.48 5 9.5 38-51 13 0.449 5.84 18.32 5 9 51-67 16 0.310 4.96 23.28 5 8 67-68 1 0.900 0.90 24.18 5 7.5 68-83 15 0.440 6.60 30.78 5 6 83-84 1 0.90* 0.90 31.68 5 6 84-95 11 0.340 3.74 35.42 5 5.5 95-101 6 0.500 3.00 38.42 5 5:5 101-117 16 0.127 2.03 40.45 5 3 14 May 1972 40m E of P2 (Fig. 9b) 0-10 10 0.215 2.15 2.15 5 9.5 10-21 11 0.310 3.41 5.56 5 7 21-24 3 0.90* 27. 8.26 5 4 24-31 7 0.421 2.95 11.21 5 4 31-36.5 5.5 0.15” 0.825 12.03 5 2 14 May 1972 90m E of P-2 (Fig. 9c) 0-12 12 .205 2.46 2.46 5 9 12-14 2 .90* 4.26 4.26 5 7.5 14-25 11 .282 7.36 7.36 5 6 25-33 8 .386 10.45 10.45 5 5 33-35 2 Ale 10.75 10.75 5 4 16 May 1972 200m E of P-2 (Fig. 9d) 0-16 16 0.210 3.36 3.36 5 10.7 16-16.5 0.5 0.90* 45 3.81 5 10 16.5-32 15.5 0.407 6.31 10.12 5 10 32-42 10 0.185 1.85 11.97 5 12 16 May 1972 300m E of P-2 (Fig. Ye) 0-14 14 0.206 2.88 2.88 5 10.5 14-15 1 0.90* 0.90 3.78 5 11 15-17 2 0.350 0.7 4.48 5 11 17-18.5 1.5 0.90* 1.35 5.83 5 11 18.5-37 18.5 0.360 6.66 12.49 5 12 37-40 3 0.510 1.53 14.02 5 12.5 40-46 6 0.15* 0.90 14.92 5 13 3 *This density value was estimated. The error in other density values is about +0.003 g cm”. 21 22 Fig. 8. Ajr temperature plot for May 1972. Temp, °c Density, g cm®> elie) SIoy Sh} io) 010 0.20 0.30 040 0.50 120 T Teal ae T i r a =]; arene: 100 leseecae| — 80 EES — £ 60 felts 40 | al 20 ip 4$ . . ° eal: AAA A A 0 x a. 28 meters east of P2 (8 meters east of road) Temp, °C Density, g cm? 15 -10 5 0.20 0.30 0.40 050 =: T T us i = We ate PROEAR LA jaey b. 40 meters east of P2 Density, g cm”® 0.20 fe) po 040 0.50 : = fou __0: ili c. 90 meters east of P2 Temp, °C Density, g cm> = Sie Olas. fo) 0.10 0.20 0.30 040 0.50 7 aa a= cscleel E40 T T + + | o “. -+ , © a 20 fn os . A A A d. 200 meters east of P2 Density, g cm™> 0.20 0.30 040 0.50 T SS pat = j e. 300 meters east of P2 Fig.9. Pit data from Prudhoe Bay. Based on the data from mid-May (Table 1 and Fig. 8), when daily range of air temperature was 10 to 20°C, let us consider a daily tempera- ture variation of 12°C (from -1°C to -13°C) and calculate the range of temperatures at 10 cm depth intervals in a snowpack 40 cm thick. The range at a selected depth Z is given by -Z y IT aP where T., is the temperature amplitude TR = 2T,e at the surface Z is depth below snow surface (cm) a is thermal diffusivity (cm? sec’') and P is the period, i.e., 1 day (86,400 sec) The calculated results are summarized in Table 3 and Fig. 11. These values are consistent with the magnitudes of temperature change observed in the snowpack during the cooling trend be- tween 14-16 May (Fig. 10). We can now estimate the daily heat exchange in the snowpack during May by asimple calculation. To do this, we shall use the bottom 40 cm of density data from Fig. Qe (i.e., neglect the top 6cm of fresh snow) together with the temperature ranges obtained in Table 3 with diffusivity = 0.0050 cm? sec’'. The calculations are summarized in Table 4. In mid-April 1972 the cold content of the snow cover at Prudhoe Bay was about 100 cal cm?, and the daily heat exchange in the snow was about one-quarter of this. When melting occurs at the snow surface, it is accompanied by localized percolation of meltwater which re- freezes to form a complex net of ice glands, lenses, and layers within the snow. The amount of heat transported downward into the snow by the percolation process is about 45 cal cm? for each cm of ice thickness formed. Some of this heat is lost in the daily cooling cycle, but a significant amount goes into warming the lower parts of the snowpack. When melting begins to wet a thick part of the snowpack, the tempera- ture profiles take the shape of the dashed line in Fig. 10. A gradient exists in the lower part, but it varies laterally in the snow because of the inhomogeneous distribution of ice masses. Dur- ing the spring only a small amount of heat must be added to raise the temperature of the entire snowpack to the melting point, yet it takes a long time for this to happen. Throughout this time the snow structure can undergo significant changes from only a few days of abnormally warm weather. The warm spell in early May 1972 reduced the amount of heat required to only one-third of the amount required in mid- April. However, a few cool days in mid-May doubled the amount required. Furthermore, ice lenses produced by the warm spell in early May remained in the snow for a month. Distribution of Snow and Windblown Dust The locations of traverses and of snow sample sites are indicated in Fig. 1. Some data on snow characteristics were presented above. A summary of the data obtained mainly from vertical core samples at 176 sample sites is presented in Table 5. To facilitate digestion of these data, they will be discussed according to: (a) water equivalent, (b) snow drifting and, (c) dust drifting. Water equivalent of the snow It is not easy to simply cite a single value for the amount of snow on the tundra. This is because of the variability in snow depth and density produced by wind drifting and the com- plexity of small-scale topographic features. We have attempted to determine average values for snow depth and density which can be used to calculate the water equivalent of snow on the tundra apart from drift traps such as banks of lakes and rivers. The average depth of undisturbed snow on the tundra at Prudhoe Bay in May 1972 was 32 cm. This value is based on 871 probe depth values that were all made more than 150 m from any road or other disturbance that may cause drifting. The average density, based on the detailed studies shown in Figs. 7 and 9, was 0.309 g cm. The water equivalent from these studies averaged 12.4 cm HO (Table 2, excluding the drift case of Fig. 9a). If we use the average density value from these studies together with the average depth of 32 cm, we obtain an average value of 9.9 cm water equivalent. 23 Temperature, °C SG) GG. Sie sie alo) -8 -6 -4 = (0) 50 Lae] tl pL aa oa (sna me | (anna L ane == | \ i 4 | € | ° 4 =H = 4 a | : 7 Zz 7 FZ Ma | 4 (eee (fae pee 1 14 Apr '72 16 May '72 (A) E of Pingo (D) 200m E of P2 1 (E) 300m E of P2 14 May '72 | June ‘72 (F) Generalized Temperature Profile Fig. 10. Summary of temperature profiles from Figs. 7 and 9. (B) 40m E of P2 (C) 90m Eof P2 Table 3 Calculated range of temperature in the snow, using three values for diffusivity, a , in units of cm2sec"! Depth below snow surface Temperature range (cm) Temp °C ye We fe 2 GA eB (e) es ey es ee es ee =} lo ] Snow Depth 20 : cm 30 40 4 Fig. 11. Calculated daily temperature ranges. 24 Table 4 Daily heat exchange in the snowpack during May (when melting does not occur). Depth below NZ p AWE snow surface (cm) (cm) gcm3 g cm-2 0-3 3.0 0.51 1.53 3-21.5 18.5 0.360 6.66 21.5-23.0 1.5 0.900 1.35 23.0-25 2.0 0.350 0.70 25-26 1.0 0.900 0.90 26-40 14.0 0.206 2.88 DWE AT AO 2a g cm-2 XE cal cm-2 cal cm2 1.53 10.0 7.6 7.6 8.19 4.0 13tS 20.9 9.54 1.6 let 22.0 10.24 1.4 0.5 22a5 11.14 1.4 0.6 23.1 14.02 1.0 1.4 24.5 *The symbols used at the top of the table are explained in Table 2. A higher average density value of 0.338 g cm? was obtained by using the vertical core sampling method along traverse T-4* on 20 May; using this value together with the average depth of 32 cm, we obtained an average value of 10.8 cm water equivalent. A density of 0.324 g cm? is obtained by averaging the values from the detailed studies with those from traverse 4. If we use this value together with the average depth of 32 cm, we obtain an average water equivalent of 10.4 cm. The latter value is consistent with Fig. 12, which summarizes all of the 150 values of water equiv- alent data from Table 5, and we will use it. In summary, we shall use the following values for the tundra snow at Prudhoe Bay during May 1972: Average depth = 32 cm; Average density = 0.324 g cm’; Average water equivalent = 10.4 cm H20. Snow drifting Snow depth profiles along three selected traverses are plotted in Fig. 13. These traverses were either parallel (T-5 and T-6) or perpen- dicular (T-9) to the winds (Fig. 1). The road in T-5 is nearly perpendicular to the winds, and large drifts form adjacent to it. The road in T-6 makes an oblique angle with the winds, and the road in T-9 is nearly parallel with the winds. In the latter case no drifting is caused by the road. The probe depth data are plotted as if the base of the snowpack were a horizontal plane. This is not true, of course, and most of the irregularities in thickness result from the irregular bottom topography; the upper surface is smoother (Fig. 6b). A convenient way to summarize the quan- tity of snow in the drifts is to measure their cross-sectional areas and to compare them with an “average cross-sectional area,’’ obtained by (0) 5 10 15 20 25 30 Water Equivalent, cm Fig. 12. Histogram of water equivalents. *This is the only traverse in which sufficient density samples (15) were taken away from the influence of roads, prior to melting. (See Table 5 and Fig. 1). 120+ West (a) T-6 8 »l4 May 1972 deck NPN or. Snow Depth, cm 2 June 1972 25 ie} = — — — -— — — — — Se a ee ey a Se te Se ae a Se | 360 320 280 240 200 160 120 80 40 40 80 120 160 200 240 280 320 360 Distance, meters Road € Bo} West (b)T-5 East 19 May 1972 Snow Depth, cm + Oo ! 1 L 1 1 1 1 1 n 1 1 4 1 Peceemerto ye 4 1 360 320 280 240 200 160 120 80 40 1 a 1 neil stall ‘a 1 a SS at i 40 80 120 160 200 240 280 320 360 ee ee ee eee ee ee ee) er ee 1 = 320 280 240 200 160 120 80 40 Fig. 13. Snow depth profiles. using the average depth of 32 cm. This has been done from the edge of the road out to a distance of 150m where the drift effect of the road is negligible. The results, summarized in Table 6, show that the drifted snow adjacent to roads generally has a greater than average cross- sectional area. However, there are exceptions, the most notable of which is in traverse T-9 where the cross-section area is 75 to 85% of the average value. This may be because traverse T-9 was made on the relatively high ground between two lakes and perpendicular to the winds. The road produced no significant drifting here be- cause it was parallel to the winds; thus, there is no significant difference between the cross- sectional areas measured on different sides of the road. Other exceptions are traverses T-1 and T-3, which lie close to the Sagavanirktok River; the cross-sectional areas of their drifts are about average or slightly less than average. Traverse T-1 is located on relatively high ground and near the sand dune area that extends westward from the river toward the dock road. This apparently is an area of higher wind erosion, as evidenced by the fact that some of the sand dunes remain bare of snow all winter. The road may serve as a partial barrier to the erosional effect of the wind and may explain why the drift on the west side is larger in this case. Similar arguments may apply to traverse T-3; although it is not near sand dunes, it is on the highest ground of all traverses. Distance, meters Traverses T-6 and T-7 are complex cases. Their snow drifts have greater than average cross-sectional areas, but they are nearly sym- metrical on either side of the road. This would imply that the east and west winds were equally effective in moving snow. However, T-6 crosses obliquely to the road, and the amount of snow available to make drifts at this site may be affected by the larger road system and associat- ed drifts lying to the west of it (see traverse T-5). Traverse T-7 may be complex because it lies adjacent to two parallel roads and its west end is on a large lake (Fig. 1). Traverses T-5 and T-8 show the greatest departure from average and the greatest differ- ence between cross-sectional areas on the east and west sides of the road. The cross-sectional area on the east side is twice that of the west side out to a distance of 80m from the road. This indicates more effective transport of snow from the west winds. It is consistent with the observation that winter storm winds, which bring new snow and have higher speeds, blow from the west (Conover 1960). The prevailing winds blow from the northeast. This appears to be a general relationship on the Arctic Slope. In large drifts on river and lake banks, the drifts formed by west winds vary in size considerably from year to year, but those formed by east winds remain essentially the same size from year to year (Benson 1969). 26 Table 5 General summary of vertical core sample data. Snow Average Water Sediments Electric Sample 1972 depth density equivalent Dust, sand, etc. cond. Bottom number Date (cm) (gcm-3) (cm) mg'cm-2 mg:cm-3 umho-cm | type 1 May 21 16.5 0.351 5.8 0.474 0.082 750 Sea Ice 2 21 34 0.334 11.3 12555 0.137 63 Tundra 3 21 3215) 0.321 10.4 0.950 0.091 102 Grass 4 21 19 0.529 10.1 8.198 0.815 94 - 5 21 33 0.380 12.5 9.369 0.747 63 Ice 6 21 42 0.377 15.9 7.768 0.490 120 Grass 7 21 32 0.270 8.7 1.414 0.162 64 Grass 8 21 41 0.254 10.4 10.003 0.959 62 Grass 9 21 36 0.255 9.2 0.996 0.109 36 Grass 10 21 19 0.397 7.5 13.322 1.766 180 Dune 11 21 33 0.337 11.1 5.406 0.487 124 Grass 12 21 Sis) 0.311 10.3 8.016 0.781 111 Ice & Grass is 21 15 0.355 5:3 7.328 ls037/7/ 114 Grass 14 21 15 0.353 5.3 0.812 0.153 63 Ice 15 21 17 0.392 6.7 4.366 0.660 80 Ice & Grass 16 23 47 0.379 17.8 7.554 0.424 60 Grass 17 23 22 0.431 9.5 22.703 2.391 78 Ice 18 23 39 0.353 13.8 14.860 1.079 103 Grass 19 23 36 0.465 16.7 24.453 1.462 141 Ice 20 23 17 0.367 6.2 1.215 0.195 82 Ice 21 23 20 0.360 De2, 0.775 0.108 81 Grass 22 23 21 0.419 8.8 2.104 0.239 79 Ice 23 23 30 0.317 9.5 1.438 0.151 55 Ice 24 23 24 0.362 8.7 0.860 0.099 69 Grass 25 23 24 0.374 9.0 0.637 0.071 53 Grass 26 23 35 0.271 9.5 2.060 0.217 75 Grass 27 23 27 0.278 Tas) 4.957 0.660 94 Grass & Ice 28 23 40 0.369 14.8 2.981 0.202 73 Ice 29 23 34 0.323 11.0 1.353 0.123 61 Grass 30 23 20 0.372 7.4 1.849 0.249 96 Grass 31 23 29 0.443 12.9 1.378 0.107 75 Grass 32 23 23 0.365 8.4 1.356 0.162 71 Grass 33 23 30 0.420 12.6 4.546 0.361 1003 Ice & Grass 34 22 41 0.389 16.0 16.865 1.057 76 Grass 35 22 41 0.326 13.4 1.878 0.141 47 Grass 36 22 30 0.336 10.1 15.514 1.539 84 Grass 37 22 30 0.286 8.6 10.574 1.234 81 Grass 38 22 35 0.329 11.5 0.197 0.017 14 Grass 39 22 35 0.317 11.1 0.267 0.024 20 Grass 40 22 23 0.239 5.5 0.153 0.028 20 Grass 41 22 23 0.290 6.7 0.131 0.020 11 Grass 42 26 28 0.432 12.1 2.126 0.176 89 Ice & Grass 43 26 35 0.415 14.5 6.016 0.415 84 Dirt 44 26 26 0.407 10.6 3.477 0.329 98 Grass & Ice 45 26 33 0.408 13°5 2.845 0.211 85 Grass 46 26 59 0.400 23.6 2.921 0.124 51 - 47 26 32 0.465 14.9 2.862 0.192 82 Ice 48 26 38 0.380 14.5 0.833 0.058 42 Ice 49 26 28 0.447 12.5 24.127 1.927 66 Ice 50 26 30 0.371 1 1.849 0.166 127 Ice 51 26 21 0.485 10.2 7.355 0.721 74 Ice 52 19 = 0.381 = 0.445 0.131 41 - 53 19 - 0.354 — 0.274 0.052 33 - 54 19 — 0.358 = 0.756 0.236 43 - 55 19 - 0.420 = 0.988 0.157 57 = 56 19 — 0.359 — 0.960 0.281 5 - 57 19 = 0.391 ~ 2.085 0.360 11 ~ 58 19 = 0.302 = 1.279 0.027 25 = 27 Table 5 continued Snow Average Water Sediments Electric Sample depth density equivalent Dust, sand, etc. cond. Bottom number Date (cm) (gcm~) (cm) mg-cm-2 mg-cm-3 pmho-cm-1 type 59 May 19 _ 0.378 _ 2.126 0.626 55 - 60 19 ~ 0.346 a 1.789 0.086 55 - 61 19 = 0.387 = 11.980 2154 56 — 62 19 — 0.330 7355 1.872 57 63 20 - 0.410 = 1.587 0.319 75 = 64 20 — 0.418 _ 1.796 0.353 63 = 65 20 31 0.325 10.1 0.233 0.023 23 Grass 66 20 31 0.290 9.0 0.447 0.050 26 Grass 67 20 = 0.247 = 1.295 0.432 77 - 68 20 ~ 0.268 - 0.129 0.040 19 - 69 20 16 0.371 6.0 0.165 0.028 61 Ice 70 20 16 0.387 6.2 0.350 0.056 37 Ice 7A 20 - 0.384 - 0.683 0.146 54 =— 72 20 — 0.356 = 0.841 0.195 58 = 73 20 35 0.336 11.8 0.724 0.062 42 Grass 74 20 35 0.329 11-5 0.673 0.059 31 Grass 75 20 — 0.256 ~ 0.053 0.017 10 - 76 20 _ 0.254 - 0.078 0.025 12 - 77 20 39 0.351 13.7 0.683 0.050 44 Grass 78 20 39 0.332 13.0 0.724 0.056 31 Grass 79 20 - 0.379 — 0.469 0.102 50 - 80 20 - 0.373 = 0.449 0.100 29 _ 81 20 41 0.221 9.1 0.447 0.049 23 Grass 82 20 41 0.336 13.8 0.880 0.064 21 Grass 83 20 = 0.265 = 0.051 0.016 10 - 84 20 = 0.267 — 0.185 0.057 9 = 85 20 31 0.334 10.4 0.313 0.030 30 Ice 86 20 31 0.343 10.6 0.367 0.035 30 Ice 87 20 _ 0.366 - 0.301 0.068 36 - 88 20 40 0.371 14.8 0.761 0.051 35 Ice 89 20 40 0.368 14.7 0.741 0.050 30 Ice 90 20 ~ 0.407 - 0.398 0.081 44 91 20 30 0.410 1253 1.995 0.162 56 Grass 92 20 - 0.384 oa 0.367 0.079 40 Grass 93 20 29 0.318 9.2 0.717 0.078 79 Grass 94 26 24 0.460 11.0 7.729 0.700 78 Ice 95 26 53 0.435 23.0 2.826 0.123 39 - 96 22 25 0.314 7.9 0.377 0.048 16 Tundra 97 22 25 0.345 8.6 1.662 0.193 25 Tundra 98 26 28 0.417 Ualez/ 12.025 1.031 146 Ice 99 26 52 0.348 18.1 3.365 0.186 Ey/ Grass 100 22 24 0.275 6.6 0.700 0.106 24 Grass 101 22 24 0.355 8.5 0.688 0.081 18 Grass 102 22 26 0.289 7/43) 0.379 0.051 30 Grass 103 22 26 0.310 8.1 0.685 0.085 40 Grass 104 26 39 0.298 11.6 3.601 0.310 66 Grass 105 26 40 0.312 12.5 1.538 0.123 36 Grass 106 26 34 0.367 12:5 8.222 0.658 129 Grass 107 26 61 0.406 24.8 0.950 0.038 77 - 108 26 26 0.318 8.3 0.841 0.102 37 Grass 109 26 26 0.453 11.8 0.311 0.026 19 Ice 110 26 36 0.328 11.8 0.248 0.021 16 Ice 111 26 22 0.299 6.6 0.515 0.078 16 Grass 112 26 29 0.277 8.0 0.296 0.037 32 Grass 113 26 32 0.248 7.9 0.073 0.009 34 Grass 114 26 41 0.354 14.5 0.658 0.045 65 Grass 115 June 8 24 0.177 4.3 0.075 0.018 12 Ice 116 8 24 0.201 4.8 0.034 0.007 6 Ice 117 May 26 20 0.365 7.3 0.083 0.011 14 Ice 28 Table 5 continued Snow Average Water Sediments Electric Sample depth density equivalent Dust, sand, etc. cond. Bottom number Date (cm) (g cm-3) (cm) mg-cm-2 mg-cm-3 pumho-cm-1 type 118 May 26 43 0.345 14.8 2.005 0.135 54 Grass 119 26 33 0.262 8.6 0.790 0.092 48 Grass 120 26 41 0.355 14.6 0.350 0.024 24 Grass 121 26 42 0.334 14.0 0.260 0.019 16 Grass & Ice 122 26 36 0.292 10.5 0.996 0.095 49 Ice & Grass 123 26 41 0.353 14.5 0.649 0.045 40 Ice & Grass 124 26 38 0.367 14.0 0.224 0.016 18 Grass 125 26 34 0.367 12:5 8.203 0.658 81 Dirt 126 26 39 0.337 13.2 1.434 0.109 64 Grass 27/ 24 33 0.378 12.5 14.724 1.181 116 Grass 128 24 40 0.438 7/As) 2.911 0.166 55 Ice & Grass 129 24 30 0.396 11.9 5.005 0.422 72 Ice 130 24 29 0.365 10.6 2.877 0.272 92 Ice 131 24 47 0.381 17.9 2.935 0.164 78 Ice 132 24 31 0.431 13.4 2.029 0.152 969 Grass 133 24 23 0.325 7/82) 5.732 0.768 969 Dirt 134 24 21 0.362 7.6 2.141 0.282 92 Grass 135 25 51 0.353 18.0 7.809 0.434 87 Grass 136 25 42 0.394 16.5 0.778 0.047 39 Ice 137 25 66 0.408 27.0 1.084 0.040 25 = 138 25 34 0.236 8.0 8.589 1.069 105 Grass 139 25 16 0.317 Sot 2.576 0.508 133 Grass 140 25 52 0.358 18.6 218.495 11.724 98 Ice 141 25 20 0.216 4.3 9.806 2.274 98 Ice & Grass 142 25 20 0.227 4.5 6.755 1.487 74 Grass 143 25 36 0.378 13.6 1.295 0.095 76 Ice 144 25 19 0.293 5.6 3.037 0.546 64 Grass & Ice 145 25 40 0.274 11.0 5.462 0.499 62 Ice 146 25 46 0.369 17.0 22.319 qe31'5 87 Ice 147 25 34 0.232 7:9 4.028 0.510 81 Grass 148 25 38 0.309 U3z/ 3.023 0.258 72 Grass 149 25 41 0.341 14.0 7.075 0.506 74 Ice 150 25 36 0.432 15.6 1a2ons 0.855 78 Ice 151 25 53 0.344 18.2 4.852 0.266 70 - 152 15 3 0.344 1:2 24.500 24.050 = - 153 15 3 0.258 0.8 5.830 7.730 - 154 15 3 0.243 0.7 2.395 SoS ~ - 155 15 4 0.263 Wes} 10.800 13.800 = - 156 15 2 0.175 0.4 9.300 17.910 - = 157 15 4 0.290 M2 9.720 11.300 = - 158 15 3 0.191 0.6 6.205 10.980 - - 159 15 4 0.394 1.6 4.300 3.315 - - 160 15 3 0.129 0.4 2.395 4.725 - = 161 15 3 0.123 0.4 0.678 12332 = = 162 25 40 0.452 18.1 18.794 1.050 98 Ice 163 25 31 0.295 9.1 11.621 N27 2 43 Grass 164 25 28 0.229 6.4 = - - Grass 165 25 30 0.276 8.3 0.432 0.052 25 Grass 166 25 43 0.254 10.9 0.396 0.036 14 Grass 167 25 28 0.300 8.4 8.161 0.971 30 Ice 168 25 38 0.398 15.1 2.435 0.161 35 Grass 169 25 28 0.353 9.9 12.569 1-275 34 Ice 170 25 41 0.285 11.7 1.064 0.091 30 Grass 171 24 21 0.362 7.6 2.141 0.282 92 Grass 172 24 21 0.239 5.0 0.510 0.102 21 Grass 173 24 30 0.281 8.4 2.658 0.316 39 Grass 174 24 38 0.257 9.8 0.950 0.097 19 Grass 175 June 5 40 0.328 13.1 1.557 0.119 219 Grass 176 5 40 0.268 10.7 2.099 0.196 564 Grass Table 6 Cross-sectional area of snowdrifts. Total 80 m from road Traverse East West E/W T-1 A Area (m~*) 25.0 26.9 Ratio 0.98 1.05 Oe T-3 ; Area (m*) 22.0 28.2 0.78 Ratio 0.86 1.10 T-5 Area (m2) 43.7 29 en Ratio lez 0.87 i T-6 5 Area (m~) 30.7 35.4 Ratio 1.20 1.38 oy T-7 p Area (m~*) 37.6 38.2 Ratio 1.47 1.49 oss T-8 Z Area (m~*) 51.2 2251 Ratio 2.0 0.86 a8 Total 80 m from road Traverse North South N/S T-9 3 Area (m~*) 19.9 PAN a7) Ratio 0.78 0.85 OS? Total 150 m from road E 150 W150 29.2 36.9 0.61 0.77 35.8 45.4 0.74 0.94 65.5 38.9 1.36 0.81 41.0 60.3 0.85 1.26 70.4 41.9 1.47 0.87 Total 150 m from road North South 35.5 36.0 0.74 0.75 29 E/W 0.79 0.79 1.68 0.68 1.68 N/S 0.99 For each traverse, the top row indicates the cross sectional area of the drift from the road to 80 m and to 150 m. The second row, labeled ‘’Ratio’’ compares the cross sectional area of the drift with the cross section area that would be made by a similar cut through snow with the constant average depth of 32 cm. At a distance of 80 m this area would be 25.6 m2, at a distance of 150 m it would be 150 m2. The cross-sectional areas summarized in Table 6 indicate the general distribution of drifted snow. However, they do not directly Depth range Average density (cm) (g cm yield information on the water equivalent in 0-50 0.34 these drifts because the hard-packed drifted 50-100 0.35 snow generally has higher density than the aver- 100-150 0.37 age tundra snowpack. A trend to higher average 150-200 0.39 density has been observed with increased snow 200-250 0.41 depth. This can be seen in Fig. 9a, compared 250-300 0.42 with the shallower pit studies. Based on data from drift traps along the Arctic Slope, the If we use these values we can calculate the water following general relationship has been establish- equivalent of slices of the drifts summarized in ed (Benson 1969). Table 6. The water equivalent of such a slice 30 Table 7 Water equivalent of a thin slice of the drift extending in both directions from road compared with average snow cover. E W E Ww Traverse 80 m 80 m E/W 150 m 150 m E/W T-1 Mass (kg) 86.300 91.700 0.94 100.650 125.750 0.80 Relative mass (1.04) (1.10) : (0.64) (0.81) ; T-3 Mass (kg) 74.900 96.400 0.78 121.800 154.850 0.79 Relative mass (0.90) (1.16) . (0.78) (0.99) : T-5 Mass (kg) 151.800 76.250 1.99 226.350 133.350 1.70 Relative mass (1.82) (0.92) : (1.45) (0.85) : T-6 Mass (kg) 105.950 121.700 0.87 173.950 206.400 0.84 Relative mass (1.27) (1.46) : (1.12) (1.32) i T-7 Mass (kg) 129.950 133.000 0.98 Relative mass (1.56) (1.60) ; T-8 Mass (kg) 179.100 75.200 2.38 244.450 142.550 171 Relative mass (2.15) (0.90) ; (1.57) (0.913) t N S N S Traverse 80 m 80 m N/S 150 m 150 m N/S T-9 Mass (kg) 67.600 74.250 155.350 122.950 Relative mass (0.81) (0.89) ‘ (1.0) (0.79) For each traverse, the top row indicates the mass (kg) of 1 cm thick vertical slice of the snowdrift extending in each direction from a road. The second row, labeled ‘’Relative mass,’’ compares the mass of a slice through the drift with a slice of ‘‘average’’ snow, i.e., with constant water equivalent of 10.4 cm H20 (10.4g cm-2) throughout its length. The mass of this average slice would be 83.2 kg if it is 80 m long, and 156.0 kg if it is 150 m long. through the measured drift can then be com- pared with a slice throughout ‘‘average snow- pack’’ as determined earlier. This is done in Table 7. The results are similar to those in Table 6, but they give the water equivalent of the drifts directly in comparison with the average tundra snow. Windblown dust The movement of dust and coarser sedi- ments by the wind is related to snow drifting, but there is an interesting difference. The most effective winds in moving these sediments are clearly from the east. The east winds move several times more dust than do the west winds. There are two main reasons for this: (a) There is a noticeable change in the direction of the strongest winds with the sea- sons. This was well summarized by Conover (1960, p. 10) from Barter Island wind roses. The strongest and most frequent winds of winter are from the west. They yield progressively from April through July to winds that are predomi- nantly from the northeast. (b) During the time when the strong west winds are most active there is little exposed sediment, so they move snow. When the north- east winds become more active the spring thaw exposes sediments in the dune area (east of T-1) and along the river channels. Also, the roads become sources of dust when they become snow-free during spring in direct proportion to the amount of traffic on them (see sequential photographs). Some comparisons of the amounts of dust on the east and west sides of major roads are presented in Table 8, which is based on the data of Table 5. The electrical conductance of the meltwater obtained from the samples is also tabulated in Table 8. The conductance values were either measured at 25°C, or corrected to 25°C by the following relationship: Co5 = M, X 0.01 [1 + 0.025(25 — T)] where Cys is the conductance at 25°C, M, is the measured conductance at temperature T, and the conductivity cell constant is 0.01. It was not possible to determine the varia- tion of the temperature coefficient for the water, and precision of 10% was considered adequate, so the single temperature coefficient of 0.025 was used. This should “’. . . be satisfac- tory for all natural waters’’ (Smith 1962). In the center part of the Prudhoe Bay area, especially along the main NW trending road, there is generally a significantly higher dust content on the west side of the road than on the east side. These are the simplest cases to inter- pret because the roads are clearly the dominant sources of dust. The dust distribution indicates that the east winds move the most dust. As we move to the eastern part of the area, especially along the road between the Prudhoe Bay airfield and the dock, we note that the west/east ratio becomes less than unity. It does not mean that the west winds are more effective dust movers in this region. Instead, it indicates that the dune area to the east of the road contributes more dust than does the road. Indeed, the road must act as a partial barrier to westward movement of sediments from the dunes. This seems to be verified by the fact that the road itself acts as a source of sediments; yet, the dust moving west from it does not add enough material to equal that from the dunes on the east. In places where 31 the roads trend east-west, the difference in dust content between the two sides decreases. In these cases the distance south or north of the road is indicated together with a parenthetical indication of east and west components where they exist. The data on electrical conductance of melt- water follow the same general trend as do the dust content data. Occasionally, we find an abnormally high conductance value such as in sample 33 by the airport, which is the highest value of all. Another high value was obtained for sample 1 (not in Table 8), which is on the sea ice and most likely is contaminated by brine. Snow Melting In the dune area east of traverse T-1, we have observed beautiful marblelike mixtures of snow and sand in drifts during winter. Prior to melting these look like mixtures of different colored sand grains. By late April and the begin- ning of May, such features are rare because the snow begins to evaporate and to melt as solar radiation is absorbed by the darker sand grains. This process continues until patches of bare soil and vegetation are exposed. Water vapor is lost Pan ain = Fig. 14. Photo of hoarfrost crystals on snow. Table 8 Distance Electrical East or West Dust Content Conductance of road (m) (gcm2) x 104 smho cm 33 Table 8 continued. Distance Sample East or West Dust Content No. of road (m) (g cm’) x 104 25 25 W 6 24 25.5 9 23 25 W 14 22 255 21 21 253 8 20 25N 12 19 25 W 245 18 25E 149 17 25 W 227 16 BOE 76 15 25 W 44 14 25E 8 1S 25 W 73 12 25E 80 11 W 54 10 E 133 9 25 W 10 8 25E 100 7 25 W 14 6 255 78 5 25 W 94 4 25E 82 g 40 W 10 2 50 E 16 by evaporation (sublimation) from the exposed soil and vegetation. The bare patches appear first on the south slopes of the dunes. Some of these were examined in detail during the afternoon of 19 April 1973. The south faces of exposed dirt had 5-8 cm of dry powdery soil on top of hard frozen ground. The north sides of these same patches had less than 0.5 cm of dry powdery soil on top of the hard frozen soil. This indicates a significant difference in the amount of drying action produced by the sun and wind. The temperature 2 cm below the soil surface on the south side was -5.8 to -7.5°C; it was -11°C at the soil surface on the north side. The snow temperature was -16 to -17°C throughout its 20 cm depth at nearby places; the time of day was 1610 and 1700. Electrical Ratio Conductance Ratio W/E umho cm"! W/E 0.66 ae 0.75 0.66 a 0.70 0.66 SS 0.98 0.64 He 1:36 2.98 1.29 5.50 S 1.26 0.91 as 1.02 0.40 — : 0.68 0.10 = 0.58 0.17 ne 0.53 1.14 = 0.67 0.62 at 1.61 A typical example of a small sand hill is shown in Fig. 14. The view is toward the north. Note the hoarfrost crystals growing on the adja- cent snow surface; these are formed downwind of the exposed bare patches. The crystals grow partly because water vapor, which enters the air over the bare patch, condenses as it moves downwind in air that cools as it passes over the snow surface. The crystals were generally on the south sides of dunes and they began immediate- ly downwind of exposed bare patches of ground. A good example of this is shown in Fig. 15, which looks west from the dune area toward the road near traverse T-1. The frost crystals appear on the south side but not on the north side of the dune, and a bare patch of soil was immedi- ately upwind of the frost crystal area. The snow 34 Fig. 15. Photo of hoarfrost crystals on snow from dirt patch. Fig. 16. Snow with sastrugi vegetation. and blades of in this area was shallower than the average thickness in 1973, just as it was in 1972 (see traverse 1 data in Tables 6 and 7). It was also wind sculptured and had bits of vegetation protruding through it (Figs. 15 and 16). When melting begins it spreads outward from the bits of protruding vegetation, which act as centers for ablation, as do the bare soil patches. The progress of snowmelt can be seen by looking at sequential aerial photographs that were taken between 24 May and 30 June 1972. No melt had occurred by 24 May except along heavily traveled roads. There are five sequences of photographs, and their locations are indicated by the rectangular areas blocked out in Fig. 1. The sequences are as follows: Sequential Photographs: Set Number 1. BP pad ‘‘N” area during breakup 1972 24 May 5 June 9 June Arrow located on west side 12 June of Pad N and pointing east. 15 June 30 June >p aoe Sequential Photographs: Set No. 2, BP Gathering Center No. 1 during breakup 1972 a. 24 May b. 5 June Arrow located on east side of ( 11 June G.C. No. 1 and pointing west. d. 13June Sequential Photographs: Set No. 3. BP Gathering Center No. 3 during breakup 1972 a. 24 May b. 5 June Arrow located on east side of o 9 June GC No.3 and pointing west. d. 15 June Sequential Photographs: Set No. 4. IBP Tundra Biome intensive study site during breakup 1972 a. 24 May b. 5 June c. 11 June Arrow located at intersection d. 13 June of BP Spine Road and Put e. 15 June River No. 1 Road and pointing f. 30 June south. Sequential Photographs: Set No. 5. BP Storage Yard area during breakup 1972 a. 24 May b. 5 June Arrow located at west end of (0%, 9 June storage pad and pointing east. d. 11 June Some brief comments on these sets of photographs are in order: Set Number 1: 1a. The gravel haul road on the left and the main road which runs east-west had heavy traf- fic, so they were dusty, and dust spread over the adjacent snow. The north-south trending road by the arrow had no traffic and, consequently, no dust. 1c and 1d. The effect of road orientation relative to wind is especially clear. The N-S road has the largest drifts, and they are larger on the east than on the west sides, as is consistent with the data from traverses T-5 and T-8 (see Tables 6 and 7). Set Number 2: 2a. The effect of a heavily traveled road on producing early. snowmelt is very clear in this photograph. 2b. The snow is nearly gone from around the heavily traveled road, but large drifts remain adjacent to the N-S road to left of center. 2c and 2d. Ponds of water are visible on the east side of the main road to right of center. This ponding is produced by the road and will contribute to its destruction. It results from the buildup of large drifts adjacent to the road, and the rapid melting of these drifts because of the dust deposited on them by heavy traffic. Set Number 3: 3a. The dust from heavily traveled roads is producing melt adjacent to the roads before the clean snow on the tundra has begun to melt. This contributes to the formation of ice masses in and at the base of the snow near the roads (see text). 3c. The larger amount of snow drifting is clearly on the east side of the roads. This indicates more effective transport of snow by the west winds. The location is midway between S35 traverses 5 and 8, both of which showed this asymmetrical distribution of drifted snow (see Tables 6 and 7 and Fig. 13). Set Number 4: 4a and 4b. The larger snow drifting on the east side combined with the larger dust drifting on the west side of the roads is apparent, especially in 4b. 4c. A minimum of snow quantity about 100 m from the roads appears to exist in some places. This phenomenon is well displayed along the roads by the arrow, especially to the left of the arrow. 4d, e, and f. Note the dry lake near the arrowhead in 4d on 13 June; it was full of water on 15 June (photo 4e), but dry again on 30 June (photo 4f). Set Number 5: This set of photographs shows the over- whelming effect of dust from the Sagavanirktok River channel in ablating snow. In 5b and 5c the most effective snow drifting is on the east sides of the roads—from west winds. On the other hand, the dust is moving west—from east winds. Radiation Climate and Snow Breakup The main objective of this section is to present radiation measurements made at Prud- hoe Bay from early spring throughout the sum- mer seasons of 1972 and 1973 and relate these data to the melting of snow cover in these areas. The observations are relatively simple compared with the complex, full energy budget measure- ments reported elsewhere (Weller et al. 1974). The intention is to demonstrate to what extent such data can be used to explain physical processes at the tundra surface. The melting of the snow cover is of particular interest in this context since it probably represents the single most dynamic microclimatic event on the tundra. The outgoing and incoming long-wave and short-wave radiations were measured by Eppley precision pyrgeometers and pyranometers, respectively—two of each at Prudhoe Bay in 1972. The radiation equipment used at Prudhoe Bay in 1973 was the same as in 1972, except that the reflected short-wave radiation was 36 ie P ise Py 4 oe epee” Z fe a. 24 May 1972 (N view). c. 9Junel , ~h- = 972 (S view). 72 June 1972 (S view). Fig. 17. Sequential photographs (above and on opposite page) of the BP Pad “N” area during breakup 1972. (Arrow located on west side of pad and pointing due east). e. f. =. 30 June 1972 (S view). 715 June 1972 (S view). 37 measured by a Moll-Gorezynski pyranometer. In principle, the determination of the net radiation by measurements of its four basic components is superior to the integrated measurements using a single all-wave net radiometer. This is par- ticularly so if the aim is to describe the radiation fluxes in terms of cloud, surface type, tempera- ture, or other meteorological parameters. Unfortunately, the Eppley precision long- wave pyrgeometers, which had become available only relatively recently, proved to be subject to large errors. In spite of extensive calibrations, both in the field by comparison with a Barnes thermal radiometer and in the laboratory with a black body device, we could not obtain consist- ent results. The errors are partly due to long- wave emission by the KRS-5 dome, supposedly semitransparent to long-wave radiation and hav- ing a low emissivity (Eppley Laboratory, 1972). After some time in use, it appears that the domes acquire an emissivity that is far from negligible. Furthermore, probably because of convection effects induced by considerable solar heating of the dark colored domes, the calibra- tion factors are not the same when the instru- ments point upward and downward. Although it is reported that the Eppley pyrgeometers may be used with some success if, among other things, the temperature of the KRS-5 dome is monitored, our experience with them shows that they are unsuitable as field instruments in their present design. We are not using the results of the pyrgeometer measurements in the present discussion. The Eppley short-wave pyranometers used in the present investigation were compared a few times in the field for internal consistency. Before and after the field season in 1972 and 1973, two of the pyranometers used were cali- brated against a Linke-Feussner actinometer. The results of these calibrations gave factors within 1-2% of those recommended by the manufacturer. For the summer temperature and humidity measurements, we used recording thermo- hygrographs in standard, white-painted instru- ment shelters. Calibrations were carried out with an Assmann psychrometer in connection with changes of the paper record. The observations were made at sites adjacent to the Gas Arctic Research Station in 1972 and 38 to the Bechtel Garage in 1973. The albedo data at Prudhoe Bay do not represent the undisturb- ed tundra since the snow in that area is generally contaminated by dust from industrial activities, mainly road dust, and by natural dust from sand dunes in the Sagavanirktok River delta area. The actual measuring locations were selected to represent approximately average snow condi- tions. Albedo measurements over a_ shallow snowpack in situations with high incoming solar radiation are extremely sensitive to any man- made or natural disturbances. Although care was taken to disturb the snowpack as little as possi- ble in connection with installation of the equip- ment and daily maintenance and inspection, some disturbances of the snowpack could not be avoided. These disturbances had a noticeable effect on the breakup patterns around the radio- meter stands. The variations of the incoming short-wave radiation and the albedo at Prudhoe Bay for the summers of 1972 and 1973 are given in Fig. 22. The general features of the radiation regime for coastal tundra are well-known since the radia- tion climate at Barrow has been investigated for many years (Ray 1885; Thornthwaite and Mather 1956, 1958: Kelley et al. 1964, 1969; Lieske and Stroschein 1968; Lieske and Bailey 1969; Weaver 1969, 1970; Weller et al. 1972, 1974; Maykut and Church 1973). During break- up, there is generally a sharp drop of the albedo from values above 80% to values of about 15-20%. The lowest values are obtained when the tundra is wet (Weller et al. 1972). At Prudhoe Bay the albedo generally varied be- tween 10 and 15% after breakup in 1973. One of the most striking features in Fig. 22 is the high variability of the incoming radiation. The cloud conditions along the coastal zone of the Arctic Ocean are similar throughout the summer with persistent decks of low stratus. On the average the National Weather Service sta- tions at Barrow and Barter Island have cloudi- ness at or above 8 tenths from May to October with a main maximum in August-September and a secondary maximum in May. The decrease in cloudiness in the middle of the summer has been ascribed by Sverdrup (1933) to a weaker inver- sion during that period. The transmissivity of the stratus for solar radiation is highly variable. Although the stratus a. 24 May 1972 (NE view). Le b. 5 June 1972 (S view). Fig. 18. Sequential photographs (above and op- posite page) of BP Gathering Center No. 7 dur- ing breakup 1972. (Arrow located on east side of GC- No. 1 and pointing due west). C. d. 73 June 1972 (S view). 39 are layer clouds, their optical properties are not very homogeneous. The cloud forms are often a transitional form between stratus and _ strato- cumulus. Frequently, the sun becomes visible through the cloud layers. The variations of the incoming solar radiation often suggested waves within the cloud layers inducing regular varia- tions of the radiation intensity. Also the emis- sivity of the thin stratus clouds appeared to be highly variable. The albedo and the surface and weather conditions The changes of the albedo in connection with snowmelt and onset of the snow cover cause a Startling increase of the net radiation and of the turbulent, sensible, and latent heat trans- fers at the surface (Weller et al. 1972). The most obvious climatic parameter affecting the snow melting is the air temperature. Daily values of the albedo and air temperature at screen height are shown in Fig. 23 (see also Fig. 8 and Table 1). As the air temperature increases and melting starts, the albedo decreases. At low air temperatures, the positive net radiation dur- ing the daytime is either used for heat conduc- tion into the snowpack, or for transport of sensible or latent heat into the atmosphere. As the air temperature increases toward or above O°C, the positive net radiation also increases, and this excess energy is used to melt and evaporate snow and to heat the air and soil in the relative proportions shown by the energy balance (Weller et al. 1974). The daily Prudhoe Bay temperature data are from the unpublished BP radio station data obtained in the vicinity of the Mukluk Camp (Brown et al., this volume) about 8 km from the coast. One may note that in the Prudhoe Bay area, the albedo in 1972 appears to decrease in con- nection with relatively low daily air tempera- tures. This is probably due to dust contamina- tion of the snow. In May 1973 the albedo values are for a short time above 80%, even with air temperatures above freezing, but then they drop suddenly. The observation site in 1973 was not the same as in 1972, and the influence from dust may have been slightly less in 1973. Further- more, on 24 May 1973 a thin layer of new snow 40 b. 5 June 1972 (SW view). Cues June 1972 (SW view). d. 15 June 1972 (SE view). Fig. 19. Sequential photographs of BP gathering center location No. 3 during break- up 1972. (Arrow located on east side of GC- No. 3 pad and pointing due west). was observed on top of the old snowpack, which temporarily increased the albedo. The albedo variations shown in Fig. 23 are only typical values that vary from one spot to another, particularly during melting. During breakup the snow cover disintegrates into patches, with bare ground appearing at an early stage where the snow is shallow. The albedo of the remaining snow patches should generally be much higher than the values representing the latter part of the melting period shown in Fig. 23. One might guess that for clean snow the albedo remains around 70% or so, except during the last stages, when the snow generally was coarse-grained and perhaps often consisted of superimposed ice. The albedo of the snow patches might then have been considerably lower. On 5 June 1973 the total snow area in the vicinity of the measuring site at Prudhoe Bay was estimated to be approximately 15% of the tundra surface. Away from the road system and the camps, etc., the snow area was estimated to be approximately 50% on the same day. It is obvious that point albedo measurements cannot be used for interpretations of the average conditions over larger areas during snowmelt. An illustration of this is shown in Table 9, where values are given of the incoming solar radiation, the albedo, and the absorbed radiation at two measuring places 8 m apart, but with a 10-20 cm deep trench causing slightly increased snow ac- cumulation under one of the sensors. The differ- ence in absorbed radiation between these two adjacent places during this 10-day melting period is almost 700 cal cm*?, corresponding to the energy required to melt about 9 g of ice per sq cm, or almost the entire snowpack, as far as the average conditions go. The influence of various climatic parameters and microtopography on the breakup is obvious- ly very complex. As long as the albedo is high, the net radiation is generally higher with over- cast skies than with clear skies (Liljequist 1956; Holmgren 1971; Ambach 1974). Later, when the albedo is lowered by melting, the net radia- tion will be higher with clear than with cloudy skies. Satellite observations show that the breakup on the Arctic Slope generally proceeds from the upper foothills into the coastal plains (Holmgren et al. 1975). Furthermore, the melt season advances faster along the major rivers when 41 Table 9 Daily insolation, albedo, and difference in absorbed radi- ation at two adjacent observation sites at Prudhoe Bay. Difference in Day Insolation A; Ag AA absorbed radiation Galidays 95 19 1% cal day | 05.26 720 68 68 0 0 05.27 675 6567 2 14 05.28 575 57, 66 9 52 05.29 361 55 65 10 36 05.30 449 48 63 15 67 05.31 321 10) (G7/ 1N7/ 55 06.01 273 40 61 21 57 06.02 317 34) 56822 70 06.03 310 Sipe on e2 68 06.04 382 271 AG) 19 73 06.05 434 29 bile 22: 95 06.06 453 24 40 16 72 06.07 511 15) 20 5 26 06.08 590 15a 0 0 Sum 6371 685 meltwater, flowing down the rivers, floods the snow cover, reduces the albedo, and causes increased absorption of radiation. On the region- al scale there exists a north-to-south temperature gradient from the coast and inland toward the valleys in the Brooks Range in spite of an increase in elevations from sea level to about 600 m over that distance (Conover 1960). At Prudhoe Bay temperature gradients from the shore to about 25 km inland were measured to investigate possible effects on the breakup by the proximity to the Arctic Ocean (Brown et al., this volume). Fig. 24 shows some maximum and minimum daily temperatures from Point McIntyre, 75m from the shore, and from a point on the Sagavanirktok River, approximate- ly 20 km south of the Deadhorse Airfield. The greatest differences are observed in the maxi- mum temperatures during the main summer period. In spring, before and during the first part of the snowmelt, the temperature differences are hardly significant for either the maximum or minimum temperatures. The same applies for the period around freezeup. The minimum tem- peratures are on the average only a few degrees above 0°C in midsummer. The surface tempera- ture contrast between land and sea is apparently small at night. 42 Table 10 Observations of radiation temperatures of various surfaces at Prudhoe Bay, 1972 and 1973. Time Surface Cloud Cloud Day A.D.T. Temp. Surface Type Temp. Type 1972 08.22 2135 6.4 Grass -35.0 Ci 10/10 2135 8.9 Puddle -35.0 Ci 10/10 08.23 15.30 10.0 Grass No meas. AsCi 10/10 09.20 14.22 0.2 Melting snow = 516 FsSt 10/10 14.22 0.9 Mud, dark brown =1526 FsSt 10/10 14.22 1.6 Gravel - 5.6 FsSt 10/10 15.30 - 0.3 Sea ice OES FsSt 10/10 15.30 0.4 Sand = 3:3 FsSt 10/10 15.30 - 0.6 Snow =e Oro FsSt 10/10 15.30 - 0.9 Sea water = Bis} FsSt 10/10 20.25 - 2.1 Snow grass - 74 FsSt 10/10 09.21 15.45 - 4.6 Snow on top of pingo - Cs 2/10 15.45 1.2 Soil on top of pingo = Cs 2/10 15.45 - 2.6 Snow on slope facing sun ~ Cs 2/10 15.45 7.9 Soil on slope facing sun — Cs 2/10 15.45 - 6.6 Snow on shaded slope — Cs 2/10 15.45 = 16511 Soil on shaded slope = Cs 2/10 21.00 -10.6 Snow grass = Cs 2/10 1973 06.06 13.45 2.4 Water logged tundra 2.6 St 10/10 13.45 49 Small puddles 2.6 St 10/10 07.15 15.03 7.9 Wet tundra 0.9 St 10/10 09.06 22.00 3.5 Lake No meas. St 10/10 Drizzle 22.00 1.4 Gravel No meas. St 10/10 Drizzle 09.07 09.50 3.5 Lake - 3.6 St 10/10 09.50 2.6 Gravel - 3.6 St 10/10 10.11 14.02 3.6 Snow - 5.6 St 10/10 14.02 0.0 Slush at the bottom of the snow cover Visual observations in connection with occa- sional helicopter flights on 4 and 5 June 1973 did not indicate that the breakup on the coast was later than it was a few tens of kilometers inland. In the Prudhoe Bay area a slight advance- ment of the breakup could be observed, how- ever. Earth Resources Technology Satellite (ERTS) images of Prudhoe Bay on 27 May 1973 also indicated that the breakup in the coastal zone was not much influenced by distance to the shore. On the other hand, the influence of natural and man-made dust was quite obvious in the satellite data (Holmgren et al. 1975). Another feature of the surface characteris- tics during breakup is the large spatial and temporal variability of the surface temperatures. Table 10 gives radiation temperatures of various surfaces as measured by a Barnes thermal radio- meter with a field of view of about 2° and sensitive to radiation within the 8-14 um band. The values in Table 10 represent averages of a few readings for each surface type. In the in- dividual case, the local temperature variations might be much higher. As soon as the ground becomes bare of snow in early spring, the sur- face temperature increases rapidly at daytime because of the increase of the absorbed solar radiation. At night the temperature differences between various surface types are generally small. With high surface temperature and increased turbulent fluxes of sensible and latent heat from the bare ground, one may generally expect increased rates of melting as warm and moist air is advected over the remaining snow. On the microscale, stable internal boundary layers will prevail over the bare ground. We also observed rapid increases of the water temperature of the puddles due to high values of the solar radiation, allowing high rates of evapo- ration. Several times during the breakup period we observed fog-smoke over ice-free ponds and over the waterlogged tundra in relatively cold weather, indicating high rates of evaporation. During a 4-day period after snowmelt in June 1971, Weller et al. (1972) found evaporation rates of 4.5 mm per day at Barrow. Melting of a snowpack with high albedo generally starts when the air temperature in- creases toward O°C. The importance of the vertical turbulent fluxes of sensible and latent heat in the melting process and, indirectly, the air temperature, is especially apparent during brief spells of warm weather in early spring. For instance, the rise of air temperatures above 0° C in connection with warm air advection on 5-6 May 1972 at Prudhoe Bay induced melting and the formation of ice lenses within the snowpack (see Physical Characteristics of the Snow, above). After the air temperature decreased, the percolat- ing meltwater in the snowpack refroze again. During the main breakup period on the tundra, the influence of the air temperatures is not as evident as during the early spring period. On the other hand, there are reasons to always consider the melting above an extensive snow- field as the combined effect of the net radiation at the surface and the warm air advection since the total radiation budget of the surface- atmosphere system is always negative over a snow surface. In other words, the energy input from the snow surface into the atmosphere is too small to compensate for the radiation energy losses of the atmosphere. This is why melting at 43 the surface is closely related to advectional effects above the surface. Since the air temperatures at the end of May and at the beginning of June appear to vary around O°C in the coastal zone of the Arctic Ocean, with relatively small variations in differ- ent weather situations, the advection effects on the melting process may become less apparent than during the brief early melting periods. Also, as bare patches of the ground appear, a rapid warming of the surface takes place, changing the microclimate around and over the remaining snow patches. At this stage, the large-scale advection effects should become less important in relation to the advection on the microscale. Exactly when the snow starts to melt and exactly when it is gone is a matter of subjective judgment. Roughly, the melting takes place in 2-4 weeks. During part of that period the snow surface is at the melting point. However, espe- cially when light melting occurs intermittently, it is difficult to judge whether or not the surface is melting. Any single meteorological parameter is then a rather poor indicator of the snow surface temperature. Part of the problem is related to the fact that snow is semitransparent to short-wave radiation. The short-wave incom- ing radiation that penetrates the surface is absorbed at depth, most of it within the first few centimeters. At the surface the emitted long-wave radiation is generally greater than the incoming long-wave radiation, and the net radia- tion budget of the uppermost surface layer may be negative. In situations with air temperatures slightly above or below O°C, the surface is often frozen, while internal melting occurs in the snowpack. The penetration of solar radiation into the snowpack and the physics of the melt- ing have been discussed in detail by Liljequist (1956). Toward the end of the breakup the flat tundra may be regarded as an extensive shallow lake, as far as the surface conditions go. The highest amounts of snow accumulation are found in shallow depressions and in the sastrugi. Ground observations and also observations dur- ing helicopter flights in the Prudhoe Bay area on 4 and 5 June 1973 indicated that a considerable damming of the meltwater may be caused by the snow and possibly by the superimposed ice in the natural shallow drainage channels. As the 44 b. Paine 1972 (N view). = d. 13 June 1972 (S view). Fig. 20. Sequential photographs (above and opposite page) of the 1BP Tundra Biome intensive site during breakup 1972. (Arrow located at intersection of BP Spine Road and Put River No. 1 road and pointing due south). eC f, 715 June 1972 (N view). za : “a ro — Ose « 30 June 1972 (S view). 45 general conditions for snowmelt on the tundra become more favorable toward the end of the melting period with increasing air and water temperatures, the remaining snow may suddenly disappear, allowing a rapid drainage of the melt- water. This may contribute to the sharp peaks in the hydrograph curves of the rivers that origi- nate on the coastal plains (Carlson et al. 1974; Dingman 1973). A few days after peaking, the runoff from melting subsides greatly. Since much of the subdued tundra terrain was ob- served to be waterlogged during a considerable time after the snowmelt in 1972 and 1973, but with decreasing depths of the standing water, it seems likely that a substantial amount of the meltwater evaporates from the tundra surface each year, although part of the meltwater may infiltrate the active layer. Observations on the Meade River and in the Noluck Lake region indicate that much of the snow may disappear before runoff occurs (Benson 1969; Johnson and Kistner, 1967). Concluding Remarks The seasonal snow cover on the Arctic Slope near Prudhoe Bay contains about 10 cm water equivalent. The snow in the Brooks Range is about three times this amount. The snow is subject to drifting from east and west winds; the west winds are more effective than the east winds as snow drifters. Dust is blown onto the snow from the channels of the Sagavanirktok River and, after April, from roads which have traffic. The dust from roads is proportional to the amount of traffic (see sequential photo- graphs). The riverbed and adjacent dune areas produce much more dust than do the roads. The east winds are more effective than the west winds as dust movers. The first melt action produces ice lenses, layers, and glands in the snow. These are imper- vious to airflow and -produce structural and thermal effects that may be significant to ani- mals such as lemmings, which live under the snow. The melt that produces these ice masses may come a month before the temperature of the entire snowpack is raised to the melting point. The thaw period proceeds by rapid melt- ing of the snow from centers of ablation such as 46 i) S >: = a. 24 May 1972 (NE view). c. 9June 1972 = = = = ee E SS p i = > ‘ - : ee b. 5 June 1972 (S view). d. 77 June 1972 (SW view). Fig. 21. Sequential photographs of BP storage yard during breakup 1972. (Arrow located at west end of storage pad and pointing due east). dune areas, roads, and, near the end of the season, from protruding bits of vegetation. Once the temperature of the entire snowpack reaches the melting point and melt action is continuous, the snow will disappear in about 2 weeks. In 1972 the snow did not reach 0°C throughout until after 28 May. By 8 June 25% to 50% of the ground was snow free; by 9 June it was 50% snow free. A strong gradient exists in the tundra climate. The coastal influence maintains the snow cover at Prudhoe Bay and Barrow for several weeks longer than at sites only 50 to 100 km inland. On 7 June 1972 there was no snow on the tundra south of Franklin Bluffs, yet the snow was still present in the Prudhoe Bay region. The images from ERTS may be especial- ly useful in observing this phenomenon. Acknowledgments This project was funded primarily from NSF funds provided to the Tundra Biome Program at the University of Alaska. Supplemental assistance was provided by the State of Alaska and industry funds. 700 z millical/cm® min W\4ary, JULY SOLAR RADIATION ALBEDO i972 SOLAR RADIATION ALBEDO SOO- 47 References Ambach, W. (1974). The influence of cloudiness on the net radiation balance of a snow surface with high albedo. J. Glaciol, 13(67) :73-84. Benson, C. S. (1962). Stratigraphic studies in the snow and firn of the Greenland Ice Sheet. SIPRE(CRREL) Research Report 70, 93 pp. . (1967). A reconnaissance snow survey of Interior Alaska. Geophysical Institute, University of Alaska, Report UAGR-190, December 1967, 71 pp. (1969). The seasonal snow cover of Arctic Alaska. Arctic Institute of North America (AINA) Research Paper No. 51, 80 pp. Brown, J., R. K. Haugen, and S. Parrish (This volume). Selected climatic and soil thermal characteristics of the Prudhoe Bay region. Carlson, R. F., W. R. Norton, and J. McDougal (1974). Modeling snowmelt runoff in an arctic coastal plain. Institute of Water Re- sources, University of Alaska, Report No. IWR-43, 72 pp. {e) millical /cm@ min MAY JUNE 1973 Fig. 22. Incoming short-wave radiation and albedo at Prudhoe Bay during the summers of 1972 and 1972. 48 % PRUOHOE BAY 1972 °¢ ALBEDO MAY JUNE % PRUDHOE: BAY 1973 XE Yy1V BYNLVY3SdW3L MAY JUNE T= TEMPERATURE A= ALBEDO Fig. 23. Albedo and air temperature during the melting of the snow cover at Prudhoe Bay. Carson, C.E. and K.M. Hussey (1962). The oriented lakes of Arctic Alaska. J. Geol., 70(4):417-439. Conover, J. H. (1960). Macro- and microclima- tology of the Arctic Slope of Alaska. Quar- termaster Research and Engineering Center, Environmental Protection Research Division, U.S. Army. Technical Report EP-139, Natick, Mass., 65 pp. Dingman, S. L. (1973). The water balance in Arctic and subarctic regions. Annotated bibliography and preliminary assessment. CRREL Special Report 187, Hanover, N. H., 131 pp. Eppley Laboratory, Inc. (1972). Instruments for the measurement of the components of solar and terrestrial radiation. Instruction Manual, Newport, R. I., 34 pp. Hansen, B. L. (1951). Thermal properties. Chap- ter V of Review of the Properties of Snow and Ice. SIPRE(CRREL) Report 4, pp. 52-59. Holmgren, B. (1971). Climate and energy on a subpolar ice cap in summer, Part B, wind and temperature field in the low layer on the top plateau of the ice cap. Uppsala, Univer- sitet Meteorologiska, Institutionen, Med- delande, No. 108, 43 pp. (Arctic Institute of North America Devon Island Expedition, 1961-1963). Holmgren, B., C. Benson, and G. Weller (1975). A study of the breakup of the Arctic Slope of Alaska by ground, air and satellite obser- vations. /n “Climate of the Arctic’ (G. Weller and S. A. Bowling, eds.) Proc. AAAS- AMS Symp., Fairbanks, Alaska, August 1973, Geophysical Institute, University of Alaska, pp. 358-366. Johnson, P. L. and F. B. Kistner (1967). Break- up of ice, Meade River, Alaska, USA CRREL Special Report No. 118, 12 pp. Kelley, J.J., D.T. Bailey, and B.J. Lieske (1964). Radiative energy exchange over Arctic land and sea: Data 1962. Scientific Report, Dept. Atmos. Sci., University of Washington, Seattle, 205 pp. Kelley, J. J. and D. F. Weaver (1969). Physical processes at the surface of the Arctic tundra. Arctic, 22(4):425-437. Lieske, B. J. and L. A. Stroschein (1968). Radia- tion regime over Arctic tundra. Scientific Report, Dept. Atmos. Sci., University of Washington, Seattle, 23 pp. AIR TEMPERATURE 49 °c 25 AIR TEMPERATURE JULY 1972 Fig. 24. Maximum (dashed lines) and minimum (solid lines) daily air temperatures at Point McIntyre on the coast (thin lines) and 25 km inland (thick lines) during 1972 and 1973 in the vicinity of Prudhoe Bay. Lieske, B. J. and D. T. Bailey (1969). Radiative energy exchange over Arctic land and sea. Scientific Report, Dept. Atmos. Sci., Univer- sity of Washington, Seattle, 27 pp. Liljequist, G.H. (1956). Part 1: Energy ex- change of an Antarctic snow field. Short- wave radiation. Norwegian-British-Swedish Antarctic Expedition, 1949-52. Scientific Results, Vol. Il, Norsk Polar-institutt, Oslo, Norway. Maykut, G. A. and P. E. Church (1973). Radia- tion climate of Barrow, Alaska, 1962-66. J. Appl. Meteorol., 12(4):620-628. Ray, P. (1885). Report of the international polar expedition to Point Barrow, Alaska. U.S. Government Printing Office, Washing- ton, D. C., 686 pp. Smith, S. H. (1962). Temperature correction in conductivity measurements. Limnol/. Ocean- ogr., 7:330-334. Sorge, E. (1935). Glaziologische Untersuchun- gen in Eismitte, in Wissenschaftliche Ergebnisse der Deutschen Gronland— Expedition Alfred Wegener 1929 and 1930/1931. Band III Glaziologie, pp. 62-263. Sverdrup, H.U. (1933). Meteorology, Part 1: Discussion. The Norwegian north polar ex- pedition with the “Maud,” 1918-1925. Scientific Results, Vol. Il, Bergen, Norway. Thornthwaite, C. and J. Mather (1956). Micro- climatic investigations at Point Barrow, Alas- ka, 1956. Drexel Inst. Tech. Publ. Climatol- ogy, 9, No. 1, 51 pp. 50 . (1958). Microclimatic investigations at Point Barrow, Alaska, 1957-1958. Drexel Inst. Tech. Publ. Climatology, 11, No. 2, 237 pp. Trabant, D.C. and C. S. Benson (1972). Field experiments on the development of depth hoar. Geological Society of America, Mem- oir 135; Studies in Mineralogy and Pre- Cambrian Geology (B. R. Doe and D. K. Smith, eds.), pp. 309-322. Trabant, D. C., C. B. Fahl, and C. S. Benson (In press). Mass balance of McCall Glacier, Brooks Range, Alaska during the 1971 and 1972 hydrologic years. J. Glaciol. Weaver, D. F. (1969). Radiation regime over Arctic tundra, 1965. Scientific Rept. Dept. Atmos. Sci., University of Washington, Seattle, 260 pp. . (1970). Radiation regime over Arctic tundra and lakes, Scientific Rept. Dept. Atmos. Sci., University of Washington, Seattle, 112 pp. Weller, G., S. Cubley, S. Parker, D. Trabant, and C. Benson (1972). The tundra climate during snowmelt at Barrow, Alaska. Arctic, 25(4):291-300. Weller, G., C. Benson, and B. Holmgren (1974). The microclimates of the arctic tundra. J. Appl. Meteorol., 13:854-862. 52 A species of Eriophorum surrounds a pingo. EXXON Company, U.S.A. 53 Soil and Landform Associations at Prudhoe Bay, Alaska: A Soils Map of the Tundra Biome Area KAYE R. EVERETT Department of Agronomy and Institute of Polar Studies The Ohio State University Columbus, Ohio 43210 Introduction The relationship between soils and topo- graphy has been recognized for a long time and forms one of the tenets of pedology.* Ideally, soils are arranged along a topographic (moisture) gradient. Soils representing the modal points of the principal elements of the gradient possess unique morphological, physical, and chemical characteristics. Thus, within a not too broadly defined region, the definition of landscape units provides reasonable predictability as to their soils. A similar relationship exists for vegetation. In an area such as Prudhoe Bay, which generally lacks significant large-scale topographic contrasts, the morphologic identification and landscape association of soils is complex. Here microtopographic contrasts associated with pat- terned ground must be used to understand the character of the soils. Although microrelief contrasts are common- ly less than 0.5 m on much of the patterned ground, soils possessing unique characteristics occur in a predictable fashion on the different elements of the pattern. Thus, on landscapes which lack pronounced topographic contrast but possess areally extensive ground patterns, such as polygonal cells, soil associations can be delin- eated with reasonable accuracy. Objectives The primary objectives of the 1973 Prudhoe Bay soils program were: (1) to characterize and delineate the principal soil-topographic or micro- topographic associations which occur in the main Tundra Biome study area; and (2) to construct a practical numerical key through which a maximum amount of soils and landform data could be represented on a large-scale map. Principal topographic (macro and micro) elements recognized on Plate | The area selected for soils-landform and vegetation mapping is representative of the Prud- hoe Bay Unit as a whole. It includes several moderately large tundra ponds and a number of small ones; a pingo and an associated, ridge-like element, and portions of two active drainage channels which provide varied topography and drainage along the margin of the area. The remainder of the area consists of gently sloping *Pedology is the branch of soil science which deals with the investigation of the natural laws governing the origin, formation, and distribution of soils. 54 Streamside Streamside Slumping Bank Drained Pergelic Cryaquepts | Lake Margin Flat Area ZX Nistic Pergelic Cryaquepts and Pergelic Cryaquepts igh Center Polygons H GPa aplic Cryaquolls Calcic Pergelic Cryoborolls and Pergelic Cryoborolls Histic Pergelic Cryaquepts and Pergelic Cryaquolls Ruptic Histic Pergelic Cryaquepts and Pergelic Cryaquepts ae Pergelic Cryaquolls Dennis Kuklok, Arctic Environmental Information and Data Center, University of Alaska Figzeal: Schematic representation of the Prudhoe Bay terrain showing the spatial relationships among soils and terrain types. See Webber and Walker (this volume) for relationships with vegetation types. As a consequence of the thaw lakes, which continue to modify the land surface, both landforms and their soils range widely in age (Brown 1965). Radiocarbon dates of 9330 + 150 Y.B.P. and 8690 + 145 Y.B.P. were obtained from reworked organic materials beneath lake bottom deposits in a large active thaw lake in the vicinity of the Tundra Biome study area. These organic materials are believed to have been derived from a land surface(s) into which the thaw lake has expanded. interfluves with wide expanses of patterned tun- dra and relatively featureless, very wet, drained, or intermittent lake basins (Fig. 1). Because of the large mapping scale and the intimate association between ground pattern and soil type, most of the 10 relief elements recog- nized on the soils map (Plate |!) are ground pattern forms. The characteristics of the forms generally follow a microrelief classification system developed for the Barrow tundra (Carey 1972). Certain modifications and additions to this classification were required by the Prudhoe Bay terrain. The terrain-relief classes used in Plate | are based on the character of the ground surface (its pattern or lack of pattern) and the amount of vertical relief found in the field and recognizable in aerial photographs. These are outlined as follows: Soils Map Unit No. ile High-center polygons covering two- thirds or more of the ground sur- face; center-trough contrast, 0.5-1 m. 2, High-center polygons covering two- thirds or more of the ground sur- face; center-trough contrast, 0.5 m or less. Terrain-Relief Type 3: Low-center polygons covering two- thirds or more of the ground sur- face; center-rim contrast, 0.5-1 m. 4. Low-center polygons covering two- thirds or more of the ground sur- face; center-rim contrast, 0.5 m or less. 5, Transitional features; mixed high- and low-center polygons with neith- er exceeding three-quarters of the area, or low-center polygons in which the trough depth greatly exceeds the rim-center contrast. 6. Steep, eroding (collapsing) stream or pond margin banks. 7. Polygonal ground surface pattern. Polygons are neither high- nor low- center; relief contrast, 15 cm. 8. Hummocky ground, either in the form of rounded hummocks 30 cm or more in height, or flat-topped polygonal hummocks 30 to 50 cm in diameter and 30 cm or less in height. 9. Aligned, discontinuous hummock ridges. 10. No apparent ground surface pattern. In an effort to place the terrain-relief classes in a regional context, they are combined with slope classes on Plate |; 0 to 2%; > 2 to 6%, and > 6%. on] oO Principal soil types recognized on Plate | Five distinct soil types have been recognized within the area covered by Plate |, and at least two others occur beyond its limits. As a general rule, the region’s soils are shallow; the mean August thaw depth is approxi- mately 43 cm, with a range between 25 and 60 cm. The soils are mostly at or near saturation throughout much of the thaw period. Moisture contents range from less than 100% (on a weight basis) for those soils on the more elevated and/or better drained topographic positions to as much as 400% on the lower and/or more poorly drained sites. An August mean value of 225% is probably reasonable for the map area. With the exception of active frost medallions and some other mineral soil areas, the majority of soils have a surface horizon composed of a variable thickness of fibrous, peaty organic materials. The surface horizon may be underlain by one or more mineral horizons which com- monly contain wide-ranging amounts of organic materials. Although the great majority of the soils have a peaty (organic) surface horizon, few qualify as organic soils (Histosols) under present definitions of the National Soil Taxonomy (Soil Survey Staff, in press). Most fall within the defini- tions of a mineral soil order composed of soils showing, in this area, relatively weak horizon development. Names at the suborder level are indicative of soil wetness. They are prefaced at still lower orders of classification by the letters (Cry), reflecting the cold soil temperatures. Finally, one or more qualifying terms may precede the soil name which indicate the presence of a significant organic horizon at the surface (histic), or the fact the soils contain permafrost and may be subjected to some form of frost disturbance (pergelic). A soil classification scheme proposed by Tedrow et al. (1958) and commonly employed by arctic tundra ecologists is presented for correlation. Each of the distinct soil types encountered in the map area is given a numerical designa- tion. On the soils map, the soil-type number designations, in a combination of one to three digits, precede the terrain-relief number designa- tion. The map symbol is completed by the addition of a number designation indicative of the regional slope angle. The last digit indicates 56 the textural class of the mineral soil. All digits or digit groups are offset by commas. The most extensive soil type found within the map area, and probably regionally as well, is a meadow tundra soil termed Histic Pergelic Cryaquept (map unit No. 3). These soils ordinar- ily occur in association with one or more of the other major soil types by virtue of their wide- spread occurrence in the depressed centers of polygons fitting the definitions of terrain-relief map units 3 or 4. The following profile is representative of this soil. Soil type: Histic Pergelic Cryaquept* Terrain-relief: Low-center polygons (No. 3), discontinuous rims. Portion of element: Center; low,<10 cm hum- mocks cover 10% of sur- face. Vegetation: Scorpidium scorpioides and other mosses; Carex spp. Eriophorum sp. and Salix sp. Slope: 0% Depth in cm: 0-8 Greyish brown (10 YR 5/2**); organic; fiber content 20% com- posed of Carex spp. and S. scor- pioides,; considerable included car- bonate; roots abundant; boundary abrupt, smooth. Very dark grey- ish brown (10 YR 3/2) to dark greyish brown (10 YR 4/2): or- ganic loamy fine sand; fiber con- tent 30%; fibers break down with difficulty; roots common; carbon- ate reaction; boundary abrupt, smooth. 8-20 Very dark greyish brown (10 YR 3/2) loamy fine sand; medium and coarse fiber; fiber content 50%; fibers break down easily; carbon- ate reaction; roots common; boundary abrupt, smooth. * All classification assignments are tentative. ** Refers to Munsell color charts. 20-25 Very dark greyish brown (10 YR 3/2) and very dark brown (10 YR 2/2) organic fine sand; medium and coarse fibers; fiber content 50%; fibers break down easily and nearly completely; carbonate re- action; weak platy structure; roots few; boundary abrupt, smooth. Very dark greyish brown (10 YR 3/2) very fine sandy loam; very weak carbonate reaction; weak platy structure; frost. 25-26.5 These soils are normally alkaline throughout the profile, ranging between pH 7.0 and 8.0. Soils of this group occasionally may have very high sodium levels. August field moisture is near 200% (oven dried basis—odb). The means of the few fluid transmission rates available for these soils indicate K = 10.2 cm hr! in the upper 10 cm, decreasing to K = 8.4 cm hr! between 10 and 20 cm. A soil very closely associated with the one just described is designated on Plate | as map unit 4. However, it is restricted in its distribu- tion to polygon center areas with standing water or to nonpatterned areas with standing water near ponds. There is not sufficient morphologi- cal reason within the confines of the National Soil Taxonomy to classify it differently from soil unit No. 3. The soils do differ, however, primarily in that those designated No. 4 may have organic horizons which are somewhat thicker and less decomposed than those of soil unit No. 3. August water tables seldom drop below the ground surface. Saturated hydraulic conductivities are usually somewhat higher in the No. 4 soils, due probably to increased porosity of the less decomposed and thicker organic horizon. Soils designated as unit No. 2 on Plate | occupy the raised polygon rims and are associat- ed especially with terrain-relief unit 3. These soils with slight morphologic variations can also be associated with any of the first 6 terrain-relief units. Because they occupy the drier (better- drained) sites, they are commonly associated with raised center polygons along eroding stream or pond banks. Soils of this group have been designated as Pergelic Cryaquolls. This classifica- tion recognizes the distribution of finely divided organic materials and dark coloration through- out much of these shallow profiles as well as their wetness. Like most other soil types of the area, they are alkaline with pH’s generally greater than 7.0. They have relatively low moisture con- tents—the August mean is near 150% (odb). Much of this moisture is retained in capillary pores (as opposed to free-draining voids in the fibrous organic horizons of the soils just described). Hydraulic conductivity values are close to K = 7.0 cm hr! in the upper 10 cm of the profile and reflect the somewhat looser, occasionally granular, texture of this horizon. Below 10 cm, values drop to K= 1.2 cmhr'!. As will be noted in the profile below, these soils often display a thin (1 cm or less), oxidized band immediately above an equally thin zone of nodular carbonates somewhere in the near sur- face horizons. Such features indicate aerobic conditions during the summer months with pre- cipitation of carbonates and oxidation of iron. The following profile is representative of soil unit No. 2. Soil type: Pergelic Cryaquoll Terrain-relief element: Units 1 through 6, espe- cially low-center polygons (No. 3) and steep eroding stream or pond banks (No. 6). Portion of element: Rims and high-center poly- gons. Vegetation: Dryas integrifolia; Salix spp.; Papaver sp., and acro- carpous mosses. Slope: 0-10% Depth in cm: 0-5 Dark brown (7.5 YR 3/2) to very dark greyish brown (10 YR = 3/2) organic loamy fine sand and silt; many uncoated quartz grains; or- ganic matter medium to coarse fibrous; roots abundant; boundary abrupt, smooth. 57 5-8 Yellowish red (5 YR 5/6) organic silt loam; quartz grains heavily coat- ed with iron; massive; roots com- mon; free nodular carbonates near lower boundary; boundary abrupt, irregular. 8-20 Very dark brown (10 YR 2/2) to very dark greyish brown (10 YR 3/2) organic loam or loamy fine sand; fiber content 40-50%; breaks down easily; massive to coarse, weak platy structure; boundary abrupt, smooth. 20-38 Very dark brown (10 YR 2/2) to very dark greyish brown (10 YR 3/2) loamy fine sand; finely divided organic matter < 5%. Massive to weak, coarse platy structure; fine gravel skeleton (1-2 cm) and >2% of volume; stem fragments; bound- ary clear, smooth. 38-50 Very dark brown (10 YR 2/2) to dark yellowish brown (10 YR 4/4) loam or silt loam; may have an organic component; massive, or strong, coarse platy structure; numerous pebbles; frost. The soils designated unit 1 on Plate | are among the more interesting, from the standpoint of soil genesis, but least extensive soils in the map area. Deeply thawed and well-drained, they are developed in sands and gravels on the top and flanks of pingos and sand and gravel ridges which may be associated with pingos. The ground surface frequently has a lag gravel and/or a hummocky microrelief (where slope angles approach 10% or more). The lag fragments display carbonate encrustations on their lower surface. These soils have many characteristics com- mon to the Pergelic Cryaquolls just described. They probably represent the fullest expression of the regional climate in the well-drained envi- ronment. The following, somewhat abbreviated profile is representative of this soil. Soil type: Calcic Pergelic Cryoboroll Pingos and related sand and gravel ridges. Terrain-relief element: 58 Portion of element: Crest and upper flanks of the slope. Vegetation: Dryas integrifolia, Cas- siope tetragona, \ichens and mosses. Slope: 10-13% Depth in cm: 0-15 Very dark brown (10 YR 2/2) organic loam; massive to weakly granular in the upper few centi- meters; gravel skeleton ~ 5%; free carbonates throughout; carbonate accumulation on most skeletal frag- ments to a depth of 7.5 cm; roots common; boundary abrupt, wavy. 15-25 Dark brown to brown (10 YR 4/3) medium sand; massive; pebbles few; roots common; boundary abrupt, irregular. Yellowish brown (10 YR 5/6) fine and medium gravelly coarse sand; massive to somewhat loose; larger skeletal fragments have carbonate crusts on their underside and silt coats on top; roots few. 25-30+ The carbonate accumulations beneath the surface lag as well as on the underside of the skeletal fragments within the profile are indica- tive of the xeric environmental conditions in which they formed. The deposition of silt coats on gravel fragments at depth suggests seasonal downward movement of fines, probably due to infrequent, heavy summer rains. The exposed position of the soils precludes a snow cover sufficient to provide meltwater. The net water movement is upward, however, as in soils of map unit 2. The final soil type recognized on Plate | occurs in frost medallions (non-sorted circles) ; it is designated as soils unit 7 and classified as a Pergelic Cryaquept. These soils have a textural range from loam through loamy sand to sand. They occur as circular areas ranging from un- vegetated mineral soil to those completely cover- ed with a vegetation assemblage distinct from the surrounding meadow tundra (soil map unit 3). Those lacking vegetation undergo intense seasonal frost heaving and desiccation. Most frost medallions have some vegetation cover, and those which have been stable for an extended period have an organic horizon up to several centimeters thick. Beneath the organic horizon (if present), is a horizon which is normally above the water table and in which oxidation is the dominant process. Below this horizon, seasonal fluctuations in the water table produce alternat- ing oxidizing and reducing conditions which impart a mottled appearance to the soil. Below this zone, reducing conditions dominate. Thaw depth beneath the frost medallions is commonly double that of the surrounding mea- dow tundra, in part, because the medallions lack the insulation of the thicker organic horizons of soil unit 3. The occurrence of frost medallions is restricted to areas of meadow tundra. This asso- ciation may be further restricted to meadow tundra areas underlain by sandy textured, miner- al materials. Their aerial extent ranges widely from a few percent of the surface to near 50%. The following profile is representative of soil unit 7. Soil type: Pergelic Cryaquept. Polygonal surface with neither high- nor low- center polygons. Terrain-relief element: Portion of element: Not applicable. Vegetation: Saxifraga oppositifolia; Carex spp.; moss; lichens (Thamnolia sp. and Dacty- lina sp.). Slope: 4% Depth in cm: 0-5 Very dark greyish brown (10 YR 3/2) organic loam; soft, weak, fine aggregate structure; roots common; boundary abrupt, irregular or broken. 5-9 Yellowish brown (10 YR 5/6) to yellowish red (5 YR 4/6) silty fine sand; intermixed with dark greyish brown (10 YR 4/2) silty medium sand; massive; fine nodular carbon- ates near 5 cm; occasional pea grav- el; roots common; boundary abrupt, irregular. 9-14 Dark greenish grey (5 GY 4/1) silty medium. sand; massive; strong, coarse yellowish brown (10 YR 5/4-5/6) mottles; occasional fine gravel skeleton; roots few; bound- ary abrupt, smooth. 14-23 Dark grey (5 Y 4/1) medium and coarse sand; massive; occasional fine gravel skeleton; boundary abrupt, smooth. 23-45 Dark grey (5 Y 4/1) fine and medium sand; massive; moderate, coarse, light olive brown (2.5 Y 5/4) mottles; few roots and fine gravel; frost. These soils have an alkaline pH and display a strong carbonate reaction to HCI! throughout their profiles. In 1974 the mapping was extended to the entire roadnet area, and by late 1975 a compiled soils map will be prepared. Acknowledgments This project was funded as a subcontract from the Tundra Biome Center to the Institute of Polar Studies, Ohio State University, and utilized the Prudhoe Bay Environmental Sub- committee funds. Initial drafting of the soils 59 map was accomplished at the Institute of Arctic and Alpine Research, University of Colorado, in conjunction with the vegetation map. Both maps appear on Plate 1. References Brown, J. (1965). Radiocarbon dating, Barrow, Alaska. Arctic, 18:36-48. Carey, K. L. (1972). Classification, mapping and measurement of the distribution of micro- relief from airphotos: Barrow, Alaska. Pages 17-27 in Terrain and coastal conditions on the Arctic Alaskan Coastal Plain; Arctic environmental data package supplement 1. P.V. Sellmann, K.L. Carey, C. Keeler, and A. D. Hartwell. USA CRREL Special Report 165: Soil Survey Staff (In press). Soil taxonomy, a basic system of soil classification for making and interpreting soil surveys. Soil Conserva- tion Service, U. S. Dept. of Agri. Handbook No. 436. Tedrow, J.C. F., J. V. Drew, D.E. Hill, and L. A. Douglas (1958). Major genetic soils of the Arctic Slope of Alaska. J. So// Sci., 9:33-45. 60 Scott Parrish Aerial oblique of U.S. Tundra Biome study area. (See Plate 1.) Fertilizer runoff plots appear in upper portion of photograph between stream and snowdrift. 61 Nutrient Regimes of Soils, Landscapes, Lakes, and Streams, Prudhoe Bay, Alaska LOWELL A. DOUGLAS and AYTEKIN BILGIN* Department of Soils and Crops Rutgers University New Brunswick, New Jersey 08903 Introduction The concentration of many nutrients in a hydrological system may be defined as functions of the rate of solubilization and dilution effects. The former includes sources of nutrients derived from mineral and organic soil and sediments and precipitation, and the latter includes climatic and geomorphic factors. In this study we have investigated streams and lakes near Prudhoe Bay to define climatic, geomorphic, and soil factors which affect the amount of dissolved nutrients found in these tundra drainage systems. Durum and Haffty (1961) concluded that the major sources of nutrients in streams and lakes were weathering and soil formation. Cleaves et al. (1970) concluded that in some watersheds ‘‘chemical weathering presently is the dominant agent of erosion.’’ Several investi- gators have reported differences in the quantities of dissolved nutrients in streams and lakes (Brown et al. 1962; Kalff 1968; Toth and Ott 1969). These investigators have sampled water bodies associated with geologic formations of contrasting composition. In this study we inves- tigated the effect of soil types, all of which had been developed from the same parent material (geologic formation), on the nutrient level of several arctic streams and lakes. Included in this “Deceased. study was an evaluation of the proportion of fertilizer that will be lost to surface runoff after application on tundra soils. The results present- ed are part of a doctoral dissertation that was completed as this volume went to press (Bilgin 1975). Methods Water sampling was initiated in late June 1971 approximately 40 days after spring thaw and continued through August. The 1972 sampling was initiated in early June at the time of spring thaw and continued through mid- August. During 1971 investigations, one 1-liter sample was passed through a column of mixed- bed ion exchange resin; the rest was used for the determination of carbonate, bicarbonate, and chloride titrimetrically (Brown et al. 1962). The column was returned to Rutgers University, eluted with 100 ml of 2.5 N HCI, and calcium, magnesium, potassium, and sodium were deter- mined by atomic absorption. Phenyl mercuric acetate was added to the second set of samples and stored. At 3-week intervals these samples were taken to the Naval Arctic Research Labora- tory at Barrow and ammonia-nitrogen, phos- phate, and ferrous and ferric iron were deter- mined colorimetrically using Hach methods. 62 Table 1 Chemical characteristics of soils in the vicinity of the Prudhoe Bay region. Organic Depth Matter Carbonates CEC EC Soluble cations ppm (cm) % % pH Na NHq4 pmho Ca Mg Na meq (100 g)! Meadow Tundra Soil 75-01(120)* 3.8-17 76-02(30) 0-21 pore — a 7 46-53 255 2 er Wet Meadow Tundra Soil Bog Soil 7.5-17 6.7 78-111(b) 0-7.5 Half Bog Soil *See Bilgin (1975) for details of site description and locations. K In 1972 all the determinations, except Ca, Mg, Na, and K, were made in Prudhoe Bay using the same methods. For the aforementioned cations, separate 125 ml samples were taken at the same sampling dates and returned to Rutgers University for determination by atomic absorp- tion. On the soils, organic matter was estimated by loss of weight between 110°C and 450°C. Particle size distribution was determined by the hydrometer method (Day 1965). Conductivity and soluble cations were determined on the solution phase of a 1:7 soil to water mixture. Sodium exchange capacity was determined at pH 8.2 (Richards 1954), and ammonia exchange capacity was determined at pH 7.0 (Busenberg and Clemency 1973). Two 0.4-hectare plots on opposite sides of a small stream on the Tundra Biome intensive site were selected for fertilizer-runoff studies (site 76-02). On 14 July 1971 and also in 1972, 113.4 kg of 10-10-10 fertilizer were placed on each of these plots, nitrogen being in the form of nitrate. A 3m border on which no fertilizers were applied was maintained on both sides of the stream. Water samples were collected from different locations upstream and downstream from this site for comparison. Results and Discussion Soils The Prudhoe Bay area, part of the Arctic Coastal Plain of Alaska, is an unglaciated area of marine and nonmarine sediments (Brown 1969; Tedrow and Brown 1967; O'Sullivan 1961). It is dominated by oriented lakes, some of which are connected to one another with small drainage channels. These lakes migrate across the frozen land surface, eroding the old basins and creating new ones (Carson and Hussey 1959, 1960). In recent studies, the poorly drained soils of the Arctic Coastal Plain have been classified as Tundra soils and Bog soils (Brown 1969; Douglas and Tedrow 1953, 1960; Tedrow and Brown 1967; Tedrow et al. 1958). Depending on the drainage and wetness, Tundra soils have been classified as Upland Tundra, which defines the well-drained conditions, and Meadow Tundra, where wetter conditions exist. The sediments of the area are calcareous 63 (Douglas and Tedrow 1960) and are often capped with a calcareous loess less than 30 cm thick. The area is characterized by long slopes of 2-4% and Upland Tundra soils. Although the soils show uniformity in some general character- istics, they vary significantly in the depth of the active layer, organic matter content, degree of wetness, texture, structure, and chemical and geomorphic characteristics. Well-drained, deep, sandy soils are dominant on the banks and terraces along the Kuparuk, Putuligayuk and Sagavanirktok Rivers, on beach ridges, and along the coast, while shallowly thawed, organic-rich, silty soils dominate the poorly drained lowlands. The depth of thaw varies considerably within short distances, depending on topography, tex- ture, degree of wetness, and amount of organic matter. The presence of permafrost under a shallow active layer influences soil formation in the arctic region (Hill and Tedrow 1961). The glei process dominates the lowlands where the soils are in a saturated condition during the summer, while maximum profile development exists in the relatively deeper, well-drained upland soils. Generally, bogs are mildly to strongly acid, but due to the carbonate-bearing sediments, some bogs in the Prudhoe Bay area tend to be alkaline in reaction. Depending on moisture and amount of organic matter, these soils are classifi- ed as Bogs and Half-Bogs. Within these general soil types, patterned ground is widespread in the area (Brown 1967; Drew and Tedrow 1962; Tedrow 1962: Tedrow and Harries 1960; Webber and Walker, this volume; Everett, this volume). The distribution and type depend on geomorphic setting, age, and soil texture. Ice-wedge polygons are com- mon in wetter soils and along the old shorelines of drained lakes, while nonsorted polygons and frost scars are dominant in the drier Upland Tundra soils (Brown 1967, 1969; Tedrow 1965). In this study soils were classified according to the system of Tedrow et al. (1958). Everett's report (this volume) contains the National Soil Taxonomy equivalents. Since the study area is relatively small, data presented in Table 1 may be considered representative of most of the soils of the interfluve between the Sagavanirktok and Kuparuk Rivers within 12 to 20 km of the Arctic Ocean. These soils have many character- istics that have been previously reported for soils 64 100 80 60 40 CEC, meq(l00g)7! by Na OAc 20 4 4 4 ——— 1 4 1 — 1 1 O 2onl 40. Vico" Weer N00 CEC, meq (I00g)! by NH4 OAc Fig. 1. Relationship of Na exchange capacity to NH 4 exchange capacity. T T a as = T goo} * Surface soils OS ° Subsoils [o) Is E =i 600 2 = Oo =) 400 Oo S) To) iS © 200 uJ 1 = a to 4 i O 20 40 60 Organic Matter, % Fig. 2. Relationship of electrical conductivity of (1:7 soil:water) soil extracts to percent soil organic matter. of the area—shallow active layer, much organic matter, calcareous, pH proportional to carbon- ates, appreciable soluble salts, etc. It was not possible to accurately determine exchangeable cations because of the solubility of carbonates, which gave a sum of exchangeable cations sever- al times as large as cation exchange capacity, analytically correct but obviously impossible. Cation exchange capacity was proportional to the amount of organic matter in the soil. Sodium exchange capacity was, in nearly every instance, a little larger than ammonia ex- change capacity; in other words, all soils have an ammonia fixing capacity (Fig. 1). It should be noted that sodium exchange capacity determina- tions were made at pH 8.2, and ammonia ex- change capacities were made at pH 7. The pH dependent exchange capacity (pH 8.2 - 7) was found to be 1.2 to 2 meq (100 g)"'. Subtracting this value from the calculated ammonia fixing capacity showed that the typical soil of the area has an ammonia fixing capacity of about 7 meq (100 g)"', and that this value was independent of soil organic matter content. The relationship of electrical conductivity of soil solutions to organic matter content of the same soils is shown in Fig. 2. Electrical conductivity is a measure of the amount of readily soluble salts present in a soil. In the Prudhoe Bay area, this value is dependent on the organic matter contents of the soil. Soils high in Organic matter are usually found on the lower relief positions in the relatively low, undulating Prudhoe Bay landscape. Often these soils have water standing on their surface during much of the summer. There are two possible explanations for the accumulation of soluble salts in the low-lying organic soils. 1. The water standing on these soils forms a good evaporation surface, and soluble salts are concentrated by evaporation. 2. Much of the water found at lower eleva- tions represents runoff (either surface or sub- surface) from upland surfaces. This runoff water has been in actual physical contact with the soil for a longer period of time than the upland waters. One seldom finds equilibrium conditions in asoil since, with the comparatively short times involved, concentration of ions in the soil seldom reaches equilibrium solubilities. However, water 65 149°00' 148°40' 148°20' Fig. 3. Water sampling sites. 66 x 08 OR Oya e 1 4 i 4 9° io oe) lo oe I IO a Jun mil Jul | Aug Fig. 4. Potassium content of a small lake, 1971 and 1972. — SS ie T as 50+ (+1971 (0)1I972 oes 40} | Ca pam 2Or 20h es ° Y 4 lOrF 4 2 Seon EIZO 10. 20 10. 20 Jun Jul Aug Fig. 5. Calcium content of a small lake. T lat T T T T (*)1971 (°)1972 10. 20 10. 20 10. 20 Jun Jul Aug Fig. 6. Ammonia-N content of a small lake, 1971 and 1972. that is in contact with the soil for long periods of time should come closer to reaching equilib- rium solubilities. Actually, both of the above conditions are probably responsible for causing higher soluble salt contents in low-lying organic soils. Lakes and rivers Of the numerous water sampling locations studied, several sampling sites are shown in Fig. 3. The data from these sites are discussed in this report because they represent trends to be expected in small lakes, small streams and larger rivers in the area. Small lakes: Fig. 4, 5, and 6 show the concentrations of potassium, calcium and am- monia in a small lake for 1971 and 1972. The amount of potassium and calcium in this lake in 1971 was approximately 20-100% greater than comparable data for 1972. The ammonia concentration in 1971 was up to 500% greater than comparable concentrations found in 1972. With each of the ions, potassium, calcium and ammonia, early season values in 1971 were essentially the same as seasonally comparable values in 1972. During July and August in 1971, the concentration of these ions increased much more than the increase in concentration of the same ions during the 1972 summer. It should be noted that rainfall data are available for 1971, but comparable data are not available for 1972, which was a much wetter year than 1971. Many low areas that lost all standing water in 1971 had standing water throughout the 1972 field season. It is our opinion that the differences in slope between 1971 and 1972 are, in part, caused by these rainfall differences. In both 1971 and 1972, observations on water level in this lake were made. The depth of water de- creased as the season advanced. If one assumes that all of this loss was caused by evaporation, the concentration caused by evaporation does not account for the increased amounts of cal- cium or ammonia found in August of 1971. Since lakes occupy low-lying positions, the same explanations used to describe the soil-organic matter, soluble salt relationships apply here. Small streams: The small stream discussed here drained the Tundra Biome intensive site and was sampled at two locations, one above and one downstream from the areas where fertil- izers were applied (Figs. 7-12). At no time was fertilizer runoff detected in the stream. Early season runoff at breakup was observed in 1972. Potassium contents were very high in this melting snow-runoff. This study area was adjacent to the roadnet, and considerable dust from the road was found in the snow (Benson et al. this volume). It is generally agreed that dust particles in water are a major source of potas- sium in water, and are probably the source of this early season potassium. The contrasts between upstream and down- stream stations in 1971 and 1972 are revealing. In 1971 flow in this stream was low in late season. Between these stations the water spread out and was shallow, warmed up, and biological activity was high. In 1972, the increased rainfall caused increased runoff, deeper water, cooler water, and less biological activity. The biological uptake of ammonia caused a decrease in soluble ammonia between the upstream and down- stream sites in 1971. Increased temperatures and biological activity caused calcium to precipitate between these stations in 1971 (Hynes 1970, p. 43). In 1972, with increased flow, calcium fol- lowed its usual trend of increased concentration as the season advanced, and there was little difference between upstream and downstream sites. Large rivers: The calcium, potassium, and ammonia concentrations in the Sagavanirktok River are shown in Figs. 13, 14, and 15. The calcium and potassium levels of this large river may be contrasted with the trends observed in lakes and small streams in that the levels of these ions do not increase during the summer in the Sagavanirktok. The lowest ammonia concentra- tions we observed were found in the Sagavanirk- tok during the summer of 1972. Nitrate, phosphate, iron: The minimum detection limit for nitrate was 0.01 ppm nitrate nitrogen. In all waters in 1971 nitrate was usually 0.01 ppm or less. Slightly higher nitrate concentrations were observed at most sampling sites in 1972. The minimum detection limit for phosphate was 0.01 ppm. Most samples had less than 0.03 ppm phosphate, with no observable seasonal trends. 67 2.0. gp a (*)I971 (61972 1.6F "| K 2 ppm . 0.8} 4 ° : 'e' . 4 OA) ar J 2 ° ° ° (@) 4 4 4 4 49. i 10 20 10 20 10. 20 Jun Jul Aug _ Fig. 7. Potassium content of a small stream, 1971 and 1972 (upstream). T T T a a 140¢ (*)197I (o)1972 120F 4 } lOOF Ca gal ppm r 60Fr 4 40+ : 4 20r po 4 + fe) n 1 ai L Say res See 10 20 lOn20 10. 20 Jun Jul Aug Fig. 8. Calcium content of a small stream, 1971 and 1972 (upstream). 4.0 ro T r SSS (*)I97I 3.0F (°)1972 NH, N ppm 2.0F OF 1 o% ° Oo J Fe 4 eee 4 ———} 10 20 10 20 lo}20 Jun Jul i Aug Fig. 9. Ammonia-N content of a small stream, 1971 and 1972 (upstream). 68 2.0 T r == + 1 ———t °° (+) 1971 |.6F (o) 1972 aie t K 4 ct m ° pp ost f - ° 2 0.44 4 Oo 4 J 4 1 zt i © ant! 1 [ORZO) [ORSEZO omy 20 Jun Jul), ss Aug Fig. 10. Potassium content of a small stream, 1971 and 1972 (downstream). 100 1 See = (*)I971 BOF (o)I972 - 60} Ca | ppm aot . ° | i 1 20+ oon O L lt th “0 10 20 10. 20 10. 20 Jun | Jul Aug Fig. 11. Calcium content of a small stream, 1971 and 1972 (downstream). 2.0) ; ' - : NHN | (*)1971 (0)1972 1.0} ppm or 5 | (@) 1 S fi at —! 1 1 10. 20 10. 20 10. 20 Jun Jul | Aug Fig. 12. Ammonia-N content of a small stream, 1971 and 1972 (downstream). Considerable particulate iron was found, 0.01 to 0.5 ppm being the usual range. Particu- late iron was proportional to water aeration, being higher where water flowed rapidly with much splash or where water was very shallow and slow flowing. Conditions which are con- ducive to high particulate (ferric) iron result in low soluble (ferrous) iron. One small stream had a very high soluble iron load (0.2 to 2.0 ppm); the concentration was low in June and increased through July and August. Conclusions In small streams and lakes a dramatic change in concentration of soluble nutrients occurs during the spring melt. The meltwater effective- ly flushes out the stream or lake. As the season progresses, runoff water (both surface and sub- surface) increases the concentration of nutrients in these lakes and small streams. In some local cases the concentration of nutrients may be controlled by oxidation or biological reactions. In small watersheds the concentration of nutrients in streams and lakes is proportional to the size of the watershed and the proportion of the watershed occupied by organic soils. In large rivers nutrient concentrations are relatively stable. The large amount of water in these rivers acts as a buffer, so that a complete flushing action is not carried out by the spring melt. In both small and large watersheds the nutri- ent levels are inversely proportional to rainfall. Acknowledgments Funds for this project were provided by the Prudhoe Bay Environmental Subcommittee; laboratory space at Prudhoe was provided by BP Alaska, Inc. and laboratory equipment by NARL from Barrow. References Bilgin, A. (1975). Nutrient status of surface waters as related to soils and other environ- mental factors in a tundra ecosystem. Ph.D. dissertation. Rutgers University, New Bruns- wick, N. J., 201 pp. Brown, J. (1967). Tundra soils formed over ice-wedges, northern Alaska. So// Sci. Soc. Amer. Proc., 31:686-691. . (1969). Soil properties developed on the complex tundra relief of northern Alas- ka. Biul. Peryglacjalny, 18:153-166. Brown, J:, (G.L: Grant, Fic. Ugolini; and J. C. F. Tedrow (1962). Mineral composition of some drainage waters from arctic Alaska. J. Geophys. Res., 67:2447-2453. Busenberg, E. and C. V. Clemency (1973). Deter- mination of cation exchange capacity of clays and soils using an ammonium elec- trode. Clays and Clay Min., 21:213-218. Carson, C.E. and K.M. Hussey (1959). The multiple-working hypothesis as applied to Alaska’s oriented lakes, /owa Aca. Sci. Proc., 66:334-349. . (1960). Hydrodynamics in three arctic lakes. J. Geo/., 68:585-600. Cleaves, E. T., A. E. Godfrey, and O. P. Bricker (1970). Geochemical balance of a small watershed and its geomorphic implications. Geol. Soc. Amer. Bull., 81:3015-3032. Day, P. R. (1965). Particle fractionation and particle-size analysis. /n ‘‘Methods of Analy- sis,” Part 1 (C. A. Black, ed.). Amer. Soc. Agron. Madison, Wis., 770 pp. Douglas, L. A. and J. C. F. Tedrow (1960). Tun- dra soils of arctic Alaska. 7th Int. Cong. of Soil Sci., Madison, Wis., Vol. 4, pp. 2447-2453. Drew, J. V. and J. C. F. Tedrow (1962). Arctic soil classification and patterned ground. Arctic, 15:109-116. Durum, W. H. and J. Haffty (1961). Occurrences of minor elements in water. U. S. Geological Survey, Circ. 445, 11 pp. Everett, K. R. (This volume). Soil and landform associations at Prudhoe Bay, Alaska: A soils map of the Tundra Biome area. Hill, D. E. and J. C. F. Tedrow (1961). Weather- ing and soil formation in the arctic environ- ment. Amer. J. Sci., 259:84-101. Hynes, H. B. N. (1970). ‘’The ecology of run- ning waters.’’ University of Toronto Press, Toronto, 555 pp. 69 0.6 — (*)I971 (e)1972 io 20. | 10. 20 Jun Jul I Aug Fig. 13. Potassium content of the Saga- vanirktok River, 1971 and 1972. T r r (*)1971 (°)1972 1 4 | a ee 1 a Sst 2 Oia Olea le MONEE OR al mL IOTNEO Jun» || Jul Aug Fig. 14. Calcium content of the Sagavanirktok River, 1971 and 1972. 0.8 T T T T T T (1971 (e) 1972 0.6 NH,N tf 0.47 1 ppm | | 0.26 4 r a Ion 3208 Toner loum iO. 20 Jun Jul Aug Fig. 15. Ammonia-N content of the Sagavanirk- tok River, 1971 and 1972. 70 Kalff, J. (1968). Some physical and chemical characteristics of arctic fresh waters in Alas- ka and northwestern Canada. J. Fish Res. Bd. Canada, 25:2575-2587. O'Sullivan, J. B. (1961). Quaternary geology of the Arctic Coastal Plain, northern Alaska. Ph.D. thesis. lowa State University, 191 pp. Richards, L. A., ed. (1954). Diagnosis and im- provement of saline and alkali soils. U.S.D.A. Handbook Co. U.S. Gov. Print. Off., Washington, D. C., 160 pp. Tedrow, J. C. F. (1962). Morphological evidence of frost action in arctic soils. Biu/etyn Pery- glacjalny, 11:343-352. . (1965). Concerning genesis of the buri- ed organic matter in tundra soil. So// Sci. Soc. Amer. Proc., 29:89-90. Tedrow, J.C. F. and J. Brown (1967). Soils of arctic Alaska. Pages 283-293 jin Arctic and alpine environments (H. E. Wright, Jr. and W.H. Osborn, eds.). Indiana University Press. Tedrow, J. C. F. and H. Harries (1960). Tundra soil in relation to vegetation, permafrost and glaciation. O/kos, 11:237-249. fedrow; J. GF: J.V. Drew; (DE. Ailly and L. A. Douglas (1958). Major genetic soils of the Arctic Slope of Alaska. J. Soi! Sci., 9:33-45. Toth, S.J. and A. N. Ott (1969). Composition of surface waters of New Jersey in relation to soil series. Waters of the Big Flat Brook and the Paulins Kill, Pequest and Musconetcong Rivers. Bu//. N. J. Acad. Sci., 14:29-36. Webber, P. J. and D. A. Walker (This volume). Vegetation and landscape analysis at Prud- hoe Bay, Alaska: A vegetation map of the Tundra Biome study area. Plant Investigations 71 72 é ; : C.D. Evans, Arctic Environmental Information and Wet coastal tundra in vicinity of Pt. McIntyre. Data Center, University of Alaska, 16 June 1971 73 Vegetation Survey of the Prudhoe Bay Region BONITA J. NEILAND Department of Land Resources University of Alaska Fairbanks, Alaska 99701 JEROME R. HOK Alaska Department of Environmental Conservation Juneau, Alaska 99801 Introduction In July 1971 a survey was made of the tundra in the vicinity of Prudhoe Bay to obtain information on distributional patterns of species, plant communities, and major environ- mental features. The survey was limited to areas of ready access from the road system. The general area was grossly subdivided into “‘land- scape units’’ based on macro- and microtopo- graphy, surface material, apparent moisture, and vegetational physiognomy and continuity. Three such units were recognized: (1) dunes complex; (2) pingos and steep banks; and (3) plains. Only the gently undulating plains were dealt with at more than reconnaissance levels, and it is that unit which is discussed here. Methods The extensive plains landscape unit was sub- jectively subdivided into subunits — areas of one-half to several hectares in size, each relative- ly homogeneous and different in general appear- ance from all other subunits. A subunit might be fairly uniform throughout (e.g., ‘smooth dry plain,” an area of relatively high relief and a coarse, springy matted vegetation), or it might be a complex (e.g., the low-center polygon subunit, composed of polygon centers with vege- tation similar to that of the wet smooth plain, but separated by ridges having vegetation more similar to a smooth dry plain). Twenty-three stands were surveyed, and presence lists of species were compiled. Quadrat frequency sampling was carried out in 14 stands (i.e., specific communities). Nine of the pres- ence-only stands included sites sampled for fre- quency; a total of 28 different stands were sampled for presence. ‘’Stand’’ selection was based on vegetational appearance within the complex subunits (i.e., in a low-center polygon subunit, one set of quadrats was placed in the centers, another set on the ridges). Quadrat placement was systematic, and quadrat number and size were largely determined by species diversity and uniformity of distribution; an at- tempt was made to keep the most frequent species in the 70-80% range. Ten to 30 quadrats, 1/4 m2 or 1/8 m2 in size, were employed per stand. A one-dimensional ordination of species and stands, based on presence, was constructed by visual means, with floristically similar stands placed as close together as possible, and species ranked with other species of similar distribution on the stand array (Table 1). Stands sampled for frequency were then arrayed in the same order as those sampled for presence, and species’ percentage frequency was indicated (Table 2). 74 Table 1 Array of species and stands Ordination rank * i 23456) 7 8) 9) dOnt a2 134 SaG a8 1922062 1)22123024025 26r7e28 Species Melandrium sp. e e e Salix ovalifolia ee Viviparous grass ® ° Cardamine pratensis ee Carex marina Alopecurus alpinus Carex saxatilis alga Scorpidium scorpioides e Eriophorum scheuchzeri Saxifraga cernua e e Carex rariflora e e e Pedicularis sudetica ee eeeee eee ee Melandrium apetalum e e eee e Dupontia fisheri e Saxifraga hirculus ® Eriophorum angustifolium ee Carex aquatilis eeee Carex atrofusca Poa arctica e Polygonum viviparum ee eee Salix reticulata ee C) Salix arctica e ee ° e e e Equisetum variegatum ee ee Carex membranacea e Dryas integrifolia e Carex misandra Thamnolia subuliformis Pedicularis lanata/arctica e Salix lanata e Stellaria laeta e Eriophorum vaginatum Senecio atropurpureus Carex bigelowii eoe0ee eeeee Eutrema edwardsii e e Arctagrostis latifolia eeee e Saxifraga hieracifolia e Draba sp. e eee e@eee ee Papaver macounii__—= | | | i) oe ae eee eee eS Dactylina arctica ee ee ee Carex scirpoidea e ee e ee Silene acaulis j e ee e Draba alpina eeee0e2e Chrysanthemum integrifolium ee eee eee eie\/@\e\eie@e e e 75 Table 1 (continued) Ordination rank* 1235456) 718) 9 OMI A2 SAS Gay 1819) 202122) 23)24-25. 2627.28 Saxifraga oppositifolia Astragalus umbellatus Pedicularis capitata Parrya nudicaulis Cassiope tetragona Salix rotundifolia Saussurea angustifolia Luzula arctica Artemisia borealis Juncus biglumis Cardamine sp. Trisetum spicatum Minuartia arctica Oxyria digyna Cerastium beeringianum Hierchloe pauciflora Braya pilosa Carex rupestris Kobresia myosuroides Oxy tropis nigrescens Oxytropis deflexa *See text for stand description Stands sampled for presence-only were larger than those sampled for frequency, and in some of the latter stands, which were not sampled for presence, some rare species were undoubtedly missed in the quadrats. The result is that the presence lists for the frequency stands are short- er than those for the presence stands. The error introduced is probably not great since only rare species would be involved, but the lists are not entirely comparable. Species and Community Patterns Subunits recognized in the plains landscape are outlined below: Simple subunits: of more or less uniform appear- ance overall. 1. Old lake beds: no longer with permanent standing water, although small ponds might be found in some portions. 2. Smooth plain, dry, wet or intermediate: very uniform in appearance with respect to both vegetation and microtopo- graphy. 3. Indistinct old polygons: pattern still dis- cernible, but little present microtopo- graphic variation. 4. Patterned plain: vegetational variation apparent, but little microtopographic variation, and not divisible into one or two distinct components. Complex subunits: composed of one or two fairly discrete communities. 1. Low-center polygons: depressed wet cen- ters with water standing on or very close to the surface all season, separated by raised ridges covered by dry, springy mats of low vegetation. 2. High-center polygons, with either sand- silt or organic surface materials: raised centers covered by springy mats of low vegetation, separated by troughs 30-60 cm deep covered by wet sods. 76 Table 2 Species frequency in sampled stands. Stands ranked as in Table 1 Ordination rank * 1 2, 4 6 7 13 16 WZ 20 20 21 23 24 25 Species Melandrium sp. Salix ovalifolia Viviparous grass Cardamine pratensis Carex marina Alopecurus alpinus Carex saxatilis alga Scorpidium scorpioides Eriophorum scheuchzeri Carex rariflora Pedicularis sudetica Melandrium apetalum Dupontia fisheri Saxifraga hirculus Eriophorum angustifolium Carex aquatilis Poa arctica Polygonum viviparum Salix reticulata Salix arctica Equisetum variegatum Carex membranacea Dryas integrifolia Carex misandra Thamnolia subuliformis Pedicularis lanata/arctica Salix lanata Stellaria laeta Eriophorum vaginatum Senecio atropurpureus Carex bigelowii Eutrema edwardsii Arctagrostis latifolia Draba sp. Papaver macounii Dactylina arctica Carex scirpoidea Silene acaulis Draba alpina Chrysanthemum integrifolium Saxifraga oppositifolia Astragalus umbellatus Pedicularis capitata Ti, Table 2 (continued) Ordination rank* 1 2 4 6 Parrya nudicaulis Cassiope tetragona Salix rotundifolia Saussurea angustifolia Luzula arctica Artemisia borealis Juncus biglumis Minuartia arctica Oxyria digyna Hierchloe pauciflora Braya pilosa Carex rupestris Kobresia myosuroides Oxy tropis nigrescens Oxytropis deflexa *See text for stand description 3. Ridged plain, wet or dry: similar to either wet or dry smooth plain, but with the surface interrupted by _ irregular ridges and hummocks of 10-15 cm in height. “Wet" or “‘dry”’ designations refer to apparent surface moisture during the period of the study. Each subdivision includes only stands that are relatively extreme in appearance. Many areas did not fit into this classification and did not appear to be simple intergrades between the recognized subunits. The array of species and stands on the basis of presence is shown in Table 1. Species fre- quency values, with species and stands in the order developed and displayed in Table 1, are shown in Table 2. Neither species nor stands would be expected to show an entirely compact arrangement on a one-dimensional array, but the fact that these are as compact as they were found to be suggests that one major environ- mental gradient exerts strong influence on these patterns. In both tables, the rank numbers repre- sent the following site types: (1) the centers of low-center polygons; (2) flat areas of ridged wet plain; (3) flat areas of ridged wet plain; (4) seasonal high water area surrounding a lake; (5) flat areas of ridged wet plain; (6) seasonal high water area around a lake; (7) smooth wet plain; 17 35 40 5 S&S pie oO, Ba 33 Ul 7 17 10 5 ad. 3 5 isp 23 i 0 7 7 10 57 3 43 (8) centers of low-center polygons; (9) seasonal high water area around a lake; (10) seasonal high water area around a lake; (11) ridges of low- center polygons; (12) intermediate smooth plain; (13) intermediate smooth plain; (14) ridges of low-center polygons; (15) dry smooth plain; (16) indistinct old polygons; (17) smooth dry plain; (18) smooth dry plain; (19) ridges of low-center polygons, now flooded by waters backed up by a gravel road; (20) centers of high-center polygons with organic surface; (21) dry smooth plain; (22) dry smooth plain; (23) dry smooth plain; (24) centers of high-center polygons with sand-silt surface; (25) centers of high-center polygons with sand-silt surface; (26) dry patterned plain; (27) ridges of ridged wet plain; (28) ridges of ridged wet plain. The basic array shown in Table 1 clearly corresponds with general gradients of apparent microtopographic relief and surface moisture (from low to high and wet to dry, respectively, as the array is numbered). Since both are com- plex environmental features, the specific ‘‘caus- al’ factors may well vary along these gradients. The extreme community types are conspicuous in the field: (1) a low wet type that was consistently greener in color than any of the more raised areas and was characterized by an open stand of rhizomatous sedges, chiefly Carex 78 aquatilis, and a dense ground cover of the moss, Scorpidium scorpioides; and (2) a dry type, characterized by much standing dead plant material, which gives the type a grey-brown coloration, and having a somewhat rubbly, hum- mocky surface of mixed sedges, small shrubs and various herbs. In between these two extremes is an array of species occurrence as shown in both tables that makes classification into separate community types extremely difficult. Stands that fit the more or less wet category are somewhat easier to lump together than are stands that fit the more or less dry category, which shows high variation, and, at present, it seems that the vegetational and floristic shifts are far too subtle in this area of low variation in relief, plant size and life form to develop a rational and useful classification scheme. Suffi- cient departures from smooth normal curves can be seen in the frequency arrays of Table 2 to suggest that at least one more major environ- mental gradient may be operative in these pat- terns. The one-dimensional ordination does reveal some informative patterns of species and community distributions. In Table 1 the general species’order is that of a gradual shift from those of wet stands to those of dry stands, moving from the top of the column toward the bottom. Characteristic species toward the wet (top) are an unidentified alga, Scorpidium scorpioides, Pedicularis sudetica, Eriophorum angustifolium, and Carex aquatilis. To this group, as the alga and Scorpidi- um decreased, were added Polygonum vivi- parum, Salix reticulata, Salix arctica, Equisetum variegatum, and Carex membranacea. Largely confined to the center of the array were Cardamine pratensis, Carex marina, Melandrium apetalum, Dupontia fisheri, Carex atrofusca, Pedicularis lanata/arctica (not distinguished con- sistently in the field), Eriophorum vaginatum, Carex bigelowii, and Eutrema edwardsi/. Toward the dry end of the species list, stands were characterized by Oryas integrifolia, Carex misandra, C. bigelowii, Arctagrostis /atifolia, Draba spp., Papaver macounii, Chrysanthemum integrifolium, Saxifraga hirculus and S. op- positifolia. Additional species of the sand-silt surfaced high-center polygons and the dry pat- terned plain are those lowest in the list. When species presence is plotted against the stand ordination (Table 1), although gaps are expected and do occur in a one-dimensional array, a fairly gradual change is seen progressing from left to right. The progression of vegetational groups is from one group of species that domi- nate and characterize the wet centers of low- center polygons, the flat areas of ridged wet plains, the smooth wet plains, and the areas of seasonally high water immediately around lakes; through various intermediate mixtures of species that characterize the smooth plains, the ridges of low-center polygons, and the dry smooth plain; to the groups that dominate and characterize the centers of high-center polygons, the patterned plains, and ridges in wet ridged plains. Stands 1 and 28 had no species in common; no one species was found in all stands, and only Eriophorum angustifolium, Polygonum vivipar- um, and Salix reticulata had presence values above 75%. When the frequency values for the species of the 14 sampled stands are arrayed on the same basic ordination (Table 2), although smooth normal curves are rare, most species show fairly consistent patterns, with stands having high values being close together and the stands of low value arrayed in one or both directions away from these. Only Carex aquatilis and Scorpidi- um scorpioides show similar patterns of fre- quency distribution. Twenty-two of the total 59 species are found with percent frequency at or above 50% in one stand or another, yielding a fairly high number of important species, as compared with species that are rare within or between stands. Diversity, both in numbers of species and in number of individuals (to the extent that frequency here reflects density), is highest in the stands toward the dry end of the array. There are sufficient departures from normal curves to suggest strongly the need for additional frequency sampling and development of a two-dimensional array. Acknowledgment We thank David F. Murray and Barbara M. Murray for assistance with the site selections and plant identifications. The Prudhoe Bay Environ- mental Subcommittee and the State of Alaska assisted in funding these studies through the Tundra Biome Center, University of Alaska. 80 Jerry Brown, USACRREL, 18 June 1975 Low angle oblique of polygonal ground. Water filled troughs are underlain by ice wedges. The background shows flat coastal topography characteristic of the Prudhoe tundra, and the foreground is late snowdrift associated with the pingo relief. 81 Vegetation and Landscape Analysis at Prudhoe Bay, Alaska: A Vegetation Map of the Tundra Biome Study Area PATRICK J. WEBBER and DONALD A. WALKER Institute of Arctic and Alpine Research and Department of Environmental, Population and Organismic Biology University of Colorado, Boulder, Colorado 80302 Introduction The goal of this project is to produce a series of vegetation maps at a scale of 1:6,000 of the immediate operating areas of the Prudhoe Bay region. These maps will provide a baseline inven- tory for the area, and analysis of them can direct the future development and management of this and similar areas. In this report we will present the first map of the series which is confined to the region bordering 6 km of road in the vicinity of the Tundra Biome study area (Plate |). The map is based on a simple classification which can be constructed and interpreted by non-botanists with only a few days of training. Concomitant with the construction of the vegetation map, a soils map of the same area was made (Everett, this volume) to contribute to the same objectives as those of the present study. The soils map is also presented on Plate |. Vegetation types The vegetation of the Tundra Biome area is fairly representative of the Prudhoe Bay roadnet system. Sand dune and seashore habitats and their plant communities are, however, absent. We have recognized 13 vegetation types within the mapped area. A list of these, with brief descriptions of their characteristic species con- tent and microsite preference, is presented in Table 1. Some of these types, for example types 10 (pingos) and 11 (river bluffs), are rather broad or mixed and may need to be subdivided at a later date. The vegetation types can be described in simple terms so that they can be readily identified by non-botanists using only a few characteristics. For example, the six most common vegetation types can be identified with the knowledge of a few simple plant life torms (herb, shrub, moss, crust lichen, and fruticose lichen) and a few plant genera (Dryas, Salix, Drepanocladus, and Scorpidium). The species composition and cover of all 13 types are given in Table 2, and all 13 types are illustrated in Fig. 1. Murray and Murray (this volume) report the plant species for the Prudhoe area as of Fall 1974. Rastorfer et al. (1973) report a partial bryophyte composition of select Prudhoe areas. Carex aquatilis Type 12 _, Salix lanata hirculus ( ‘0 \ \ \ N \ \ Ne \ N Ni \ \ \ \ SS \ NS \ Re \ ~ ~ N SS SX \ x \ \ ie ~ Ne ~~ ~S x > \ ~N NS \ ~ \ Sx SN WN ~ \ \ SS N \ aquatilis Dupontia 4 fisheri Saxifraga Solix Carex al rotundifolia Sp, Chrysanthemum \ integrifolium \( Neo Oxyria digyna vy YP io De crust and fruticoset,\ {) vm lichens 720m locm Dryas integrifoliags P- 5 sedges and @ fruticose lichen: | / \ | / \ | / \ | | i \ | / \ | / \ / \ | / \ | if, \ | / \ i d \ / | / A H | oii SD | / lichens | / | / | if | / | / | | / ee / fi ierierice rs a } + 4 1 1 4 1 ‘ 4 1 ‘ Bares seinen f a es ere i 4 eit gl | | FROST BOILS leap ' ! i} [=] | ! ee ag ae fie ey on | & ow ey | STREAM | - | ws! iBLUFF| WELL DRAINED TERRAIN WITH FROST BOILS (Type 7 no vegetation | o | = I o | ! Wate i Saar pizent | ha eet RS a tear 2 fr eat | } = | °o ee a I H | ee fe See | 1 alt 1 ! 1 Fig. 1. Schematic representation of the Prudhoe Bay terrain showing the topographic and spatial interrelations of the 13 vegetation types. Eriophorum angustifolium y/ Carex moss (Orepanociadus Carex aquatilis iscm @ 15cm Carex aquoatilis SS brevifolius) ® no lichens Dryas ees if SconP Iau scDnpioiues / no lichens eZ other sedges and / dwarf willows, / Carex few or no lichens / rupestris Drygs intagrifolia i! / / y LES Oxytropis nigrescens if / all / / vA : ey) ff / y A lichens and mosses // / vA J / / I JA Cassiope / / if / YE om tetragona fell / i / / / / / / / / ly / / / / / / / / Vi a te iy i ie < / / / / y ye / /; / 4 aN Be Sif» serabees Bees | Soe Fe t 1 ae | CENTER, TROUGH f (Type 3,4) | (Type 4,5) » | i | a RIM (Type 2,3) (Type 1,2) e ! | | | | < | | = HIGH—ceNTeR | Wo! = | LOW-CENTER POLYGONS PINGO = POLYGONS < @ | THAW LAKE | = = | (Type 7, no | | 2 Ee | | vegetation ) | | 7) | = L | | | re 2 Il ! | | P SW | | | | | I L ! =I 1 | 1 Dennis Kuklok, Arctic Environmental Information and Data Center, University of Alaska Salix rotundifolia =, —4- V2 f | Arctophila fulva | Carex aquatilis 84 Table 1 The vegetation types mapped within the Tundra Biome study area, Prudhoe Bay, Alaska. For each type the characteristic species and microsites are given. Characteristic Species Most Common Types: 1. Dryas integrifolia and crust lichens. Several other cushion dicotyledons and fruticose lichens. 2. Dryas integrifolia and Cetraria spp. Several other fruticose lichens and sedges. Few or no crustose lichens. 3. Carex aquatilis and/or Eriophorum angustifolium and Dryas integrifolia. Several other sedges and dwarf willows. Very few or no lichens. 4. Carex aquatilis and/or Eriophorum angustifolium and Drepanocladus spp., usually with Pedicularis sudetica. No lichens. 5. Carex aquatilis and Scorpidium scorpioides. No lichens. 6. Carex aquatilis and/or Arctophila fulva. No mosses or lichens. No vegetation. 8. Saxifraga oppositifolia and Salix reticulata often with Juncus biglumis and several lichens. Snowbanks and Pingos: 9. Cassiope tetragona and Salix rotundifolia. 10. Diverse vegetation with Dryas _ integrifolia, Oxytropis nigrescens and Carex rupestris. Several lichens and mosses. Stream, River, and Lake Margins: 11. Diverse vegetation with Salix rotundifolia, Chry- santhemum integrifolium and Oxyria digyna. 12. Carex aquatilis and Dupontia fisheri with Saxifraga hirculus and other dicotyledons. 13. Salix lanata and Carex aquatilis. Shrubby willows with a Type 12 understory. Characteristic Microsite Tops of high-centered polygons, small ridges and high creek bluffs. Dry polygon rims, and well drained areas. Polygon rims and flat areas that are not continually wet. Centers of many low-centered polygons, troughs and poorly drained areas, such as pond margins. Very wet areas where there is shallow standing water throughout the summer. Wet polygon troughs and pond margins. Standing water of moderate depth (30-100 cm). Lake margins and thermokarst pits. Deep water ( > 100 cm). Frost boils. Snowbanks. Pingos. Slumping river bluffs, areas of erosion and/or solifluc- tion. Stream banks. Stream and lake banks. Type 3 vegetation of Carex aquatilis, Eriophorum angustifolium, Dryas integrifolia and several Salix species. The following dichotomous key, which is based on plant rather+than geomorphic or habitat parameters, illustrates the simplicity of the identification process: Key to the most common vegetation types of the Prudhoe Bay area 1. Lichens abundant Lichens rare 2. Many fruticose and crust lichens Mostly fruticose lichens ......... Type 2 3. Dryas and/or Salix spp. abundant .. Type 3 Dryas and/or Salix spp. rare ue Ame VIOSSEStaleh sku yn e.c een eee Type 6 Mosses abundant 2 5. Drepanocladus species dominant Type 4 Scojplaiunmaominant ese eee Type 5 We plan to develop a key to all vegetation types. Other functional keys using a variety of para- meters could be made, but we want to avoid mixing descriptors to reduce the problem of circular reasoning when maps are subsequently analyzed and used. Nevertheless, vegetation, habitat, and geomorphology are intimately inter- related, and it is difficult to map them separate- ly at this scale (1:3,000) because of the fine mosaic and patterning of this tundra. But we believe our method will allow a separate analy- sis. 85 We have set up and sampled a number of permanent vegetation plots in both disturbed and undisturbed areas. These plots will serve as baselines for any subsequent changes. We have also set up specimen plots of each vegetation type which can serve as training and reference samples for other potential vegetation users or mappers; these will also serve as permanent baseline plots. Mapping Method The maps were initially constructed in the laboratory using July 1972 CRREL, 1:3,000, black-and-white, air photographs on which major landscape units were then outlined. These units were identified on the basis of uniform tone, texture, and pattern. Each of these units was visited in the field, their boundaries checked and changed as necessary, and their vegetation and geomorphologic features described. The inti- mate interrelatedness of geomorphic and plant patterns makes it difficult to produce separate vegetation and geomorphic maps. Our map (Plate |), however, shows the prevalent or most abundant vegetation type for each landscape unit and also records the geomorphic features and other frequent vegetation types which occur within a unit. The vegetation and geomorphic record is given by a formula of letters and numbers. The numbers in the formula indicate the vegetation types. On polygonal ground the vegetation types are listed in 2 or 3 groups of microsites separated by semicolons (;). The first group is the vegetation on the polygon centers; the second, vegetation on the rims, and the third, vegetation in the polygon troughs. A dash indicates the absence of a group or microsite category. The letter for the most abundant vegetation type is underlined. The letters preced- ing the numbers in the formula indicate the geomorphic features of each map unit: P — polygonal ground; F — flat or gently sloping terrain where ice-wedges are masked or ill- defined; R — small ridges and hills; S — streams and stream margins; W — dunes; L — lakes and ponds, and H — pingos. Often a subscript is used to further define the geomorphic feature: F — flat polygons; L — low centered polygons; H — high centered polygons; M — mixed polygons; B — river bluffs; f — frost boils; s — sandy soil; t — thermokarst pits; and r — reticulate-ridged flats. 86 Life-form and species Erect Shrubs: Cassiope tetragona Salix lanata Total Prostrate shrubs: Dryas integrifolia Salix arctica Salix ovalifolia Salix reticulata Salix rotundifolia Total Cushion and mat dicots: Astragalus umbellatus Cerastium beeringianum Minuartia arctica Minuartia rossti Oxytropis nigrescens Saxifraga oppositifolia Silene acaulis Total Single dicots: Androsace chamaejasme Braya spp. Cardamine digitata Cardamine pratensis Caltha palustris Chrysanthemum integrifolium Draba alpina Hippuris vulgaris Lesquerella arctica Lloydia serotina Melandrium apetalum Oxyria digyna Papaver macounii Parrya nudicaulis Pedicularis capitata Pedicularis lanata Pedicularis sudetica Polygonum viviparum Potentilla hookeriana Ranunculus pedatifidus Saussurea angustifolia Saxifraga cernua Saxifraga hirculus Senecio atropurpureus Stellaria laeta Valeriana capitata Total 1(10) 0.1 0.1 48.7 0.1 0.1 2.9 0.6 52.4 0.1 0.1 0.1 9.4 OF 0.1 0.8 0.3 0.2 0.1 1.0 0.1 0.4 0.1 3.2 2(10) 0.4 0.1 0.5 59.8 6.1 0.2 2.1 0.1 68.3 0.6 0.1 1.8 25 0.1 0.5 0.1 0.1 0.3 0.1 0.2 0.3 0.2 0.1 0.1 2.6 3(10) 0.5 0.5 20.0 8.0 2.6 25 33.1 0.6 0.6 0.1 0.2 1.3 0.2 1.8 Table 2 Plant composition of the vegetation types recognized within the Tundra Biome study area at Prudhoe Bay, Alaska. Values are means of percentage cover estimates from a variable number of 1m? quadrats. These data are still preliminary and not all species encountered have been included. No attempt has been made to arrange the rows and columns in any ecological sequence. Vegetation type (number quadrats per type) 4(10) 0.1 0.1 0.2 0.2 0.5 0.5 0.5 2.0 2.5 5(10) 0.1 0.1 6(10) 0.8 1 2.3 8(10) 0.2 0.1 6.1 6.4 0.1 0.1 0.1 0.2 0.2 0.1 0.2 0.2 0.1 0.1 3) 9(3) 16.0 16.0 23.3 0.2 SL. 35.8 61.0 0.1 13 8.3 9.7 0.2 0.3 0.2 1.0 0.2 10(3) 5.8 5.8 18.3 6.1 11(4) 12 0.1 45 23.1 28.9 13.0 8.8 0.1 15.0 12(8) 0.1 0.1 0.1 25 2.8 0.6 6.0 0.6 0.1 0.1 0.1 1.4 0.1 0.6 3.1 13(6) 42.6 42.6 0.1 6.4 0.8 18.3 0.8 26.4 0.1 0.1 0.9 0.1 0.7 0.7 0.1 1.6 7.6 87 Table 2 (continued) Vegetation Type 1 2 3 4 5 6 8 9 10 11 12 13 Monocots, sedges: Carex aquatilis 40) 142 17-5 19.0 | 165 2.2 5.8 81.6) ).22.9 Carex atrofusca 0.1 Carex bigelowii 0.1 oe 0.1 0.2 0.1 0.6 0.1 Carex misandra 0.6 0.1 0.2 0.1 Carex rotundata 0.1 Carex rupestris 2.8 23] 15 Carex scirpoidea 0.2 0.1 Eriophorum angustifolium 24 110 116) 23:2 T5 74 6.7 0.1 53 104 Eriophorum vaginatum 0.4 0.1 Total 59 212 * 245) At2 = 26:6) 16:51. 12:9 _ 12:8 Ths) 0:3) S77 . 33:0 Monocots, grasses: Alapecurus alpinus 0.1 0.5 Arctagrostis latifolia O02 0.2 2.0 2.0 25 0.6 Arctophila fulva 12.5 Dupontia fisheri 0.4 0.1 0.9 0.5 0.1 19:3 13.7 Festuca baffinensis V7 5.8 1.2 Poa arctica 0.1 Total 0.7 0.7 0.1 0.9 13.0 3.8 7.8 12 26 204 13:7 Rushes and horsetails: Equisetum variegatum 0.5 0.4 2.6 0.2 0.1 0.2 2.0 2.5 0.1 0.2 Juncus biglumis 0.1 0.4 3.4 Total 0.6 0.8 2.6 0.2 0.1 3.6 2.0 2.5 0.1 0.2 Mosses: Bryum sp. 0.1 14.2 Sul 15:3 12:5 Calliergon richardsonii 0.1 3.9 3.1 15 1.6 3.9 1.0 Campylium stellatum 2.9 3.1 {te 13.6 9.0 Distichium capillaceum Ze? 0:9 114.2 0.1 95 | 20:0 10.0 1.4 9.5 Drepanocladus lycopodioides 23.1 15 Drepanocladus uncinatus 89 14.1 56.5 5.6 10.8 22.5: 55.6 Hypnum sp. 12.2) 15.8 5.8 75 50) 12.5 12 Tomenthypnum nitens 20 655 40:1 11-5) 18.8, 12.5 0.1 54 19.5 Tortula ruralis 0.1 0.1 0.6 5.8 Scorpidium scorpioides 46 30.2 0.5 Total 2541055 13860 43.0 33:2 05> 409 438 30:8 11:3) 62.1) 107-1 Lichens: Black crusts PL 6.8 Grey crusts 2.0 White crusts 23.9 0.1 1.6 ed 0.1 Alectoria nigricans 0.1 Cetraria cucullata 0.4 1A 0.2 1.8 Cetraria islandica 0.4 0.6 0.2 0.2 Cetraria nivalis 0.1 0.1 0.3 Cetraria richardsonii 0.1 0.2 Cladonia spp. 0.1 0.2 1.0 Dactylina arctica 1.8 1.0 0.6 1.8 Peltigera aphthosa 0.1 Peltigera canina 0.1 0.1 Solonina sp. 0.1 0.3 0.1 0.6 Ve. Stereocaulon sp. 0.5 0.2 4.6 (IS Thamnolia subuliformis 5.4 7.8 0.1 6.5 0.8 1.8 2 0.1 Total 46.9 119 0.2 22:2: 4.4 7.4 1155) 0.1 Total cover 145.5 |2233 210.2 122.0 | 60:0 | 32:3 107.7 1567 | 88.6 78:9. 143.9 239.7 Total number of species 49 59 30 22 8 6 41 29 22 27 27 30 88 D or d indicates either heavy or light disturbance respectively, the nature of which may be further defined by a subscript: | — organic or inorganic litter from road construction; g — gravel, equip- ment tracks, dust from road; and i — areas of impounded water. The disturbance symbols may stand alone or follow the vegetation numbers. The following examples illustrate the nature and interpretation of the formulae: F,2,8 Flat terrain with frost boils supporting type 2 vegetation of Dryas and fruti- cose lichens and type 8 vegetation of Saxifraga oppositifolia and Salix reticulata; the latter vegetation type predominating. Familiarity with the vegetation and the region permits further interpretation that type 2 vegetation occurs on stable surfaces while type 8 is restricted to the frost boils. Pi 1-73 A region of lightly disturbed, high center polygons with type 1 vegeta- tion of Dryas and crust lichens on the raised centers, with no distinct rims, and with type 3 vegetation of Carex aquatilis, and/or Eriophorum augustr- folium, and dwarf shrubs in the troughs. Discussion Vegetation. Neiland and Hok (this volume) and White et al. (this volume) have provided useful descriptions of the Prudhoe Bay vegeta- tion. The units presented here, although slightly different in content and concept, can be cross- matched with these studies. A detailed compart- son is beyond the scope of this report. Table 3, however, attempts a brief comparison of the units recognized by T. Skogland in White et al. (this volume). The 6 most common vegetation types occur along a complex site moisture gradient. This sequence from dry (Type 1) to wet (Type 6) can be seen in Table 3. A moisture ranking for all 13 types reported here from dry to wet would be: Types 1 and 10, Type 8, Type 2, Type 9, Type 3, Type 11, Type 13, Type 4, Type 12, Type 5, Type 6, and Type 7. This sequence is not linear. Fig. 1 shows the topographic and spatial inter- relations of each vegetation type. It shows that the principal environmental control on the veg- etation is site moisture as controlled by top- ography. There is a strong correspondence between the vegetation map and the soil map (Plate |) of the same area (Table 4). Admittedly, there is some circularity involved in the latter statement because the same photographic base and a land- scape unit approach was used for both maps, but the soil-vegetation and site moisture correspon- dence is inescapable. The vegetation at Prudhoe Bay can be relat- ed to that of the whole Coastal Plain (Wiggins 1951; Britton 1957) and even with vegetation of other arctic regions; for example, the Eastern Table 3 Approximate equivalents between the vegetation units used by White et al. (this volume) and those in this report. White et al. (this volume) Webber and Walker (this report) Notes Dryas integrifolia heath Eriophorum angustifolium polygon marsh Carex aquatilis marsh Salix rotundifolia snowbed Dupontia fisheri brook/meadow Salix ovalifolia sand dunes Type 1 very dry Type 2 dry Type 3 moist Types 3 and 4 extensive Type 4 wet Type 5 very wet Type 6 emergent Type 9 and/or 11 Type 12 not extensive Types 15, 16, and 17 provisional numbers; not elaborated here Canadian Arctic (Polunin 1948) and the Western Taimyr, USSR (Matveyeva et al. 1973). While the Prudhoe Bay vegetation is sufficiently dis- tant from these other localities within the tundra continuum that the present units will not be wholly applicable elsewhere, it is our opinion that the method would be applicable. The Prudhoe Bay vegetation is more diverse and contains a richer flora than vegetation at Point Barrow. This is the result of a slightly warmer growing season (Brown et al., this volume), combined with a more varied terrain and habitat spectrum. Mapping. Mapping landscape units and de- scribing their content with a series of symbols is a commonly accepted procedure (Kuchler 1967, pp. 190-194). It is a very appropriate method in these patterned landscapes, and pedologists and a geomorphologist (Brown 1969; Carey 1972; Everett, this volume), have used it effectively. The mapping method is relatively rapid and with experience, it is possible to map at this scale a square kilometer of moderately varied terrain in one man-day. The map appears to represent the vegetation of an area quite well, and potential users have found the map effective and easy to read. The tonal shading of a prevalent vegetation type on the map is potentially misleading because a prevalent or most abundant type may Type 6 vegetation of Carex aquatilis and Arctophila fulva as emergent aquatic p/ants. 89 Table 4 Correspondence of the soil types recognized in the IBP study area (Everett, this volume) and the present veg- etation types at Prudhoe Bay. The most frequent veg- etation corresponding to a soil type is underlined. Soil Type Vegetation Type (Everett, (Webber and Walker, this volume) this report) Number and Name Number 1. Pergelic Cryoboroll 1 and 10 2. Pergelic Cryaquoll 1,2,3,and9 3. Pergelic cryaquept 2,3, and 4 4. Histic Pergelic Cryaquoll (standing water) 4,5 7. Pergelic Cryaquept 8 occupy only a very small part of a landscape unit. This has not been a serious problem so far, but we are considering adding to the formula some quantitative assessment of each vegetation type within the landscape unit. Map Utilization. We have not yet made any detailed analyses of the maps. It is our intention to complete the series of maps for the entire operating area. We will continue to monitor our permanent quadrats and analyze any observed changes. We also plan to make a phytosociological analysis which will elucidate, in detail, the environmental factors controlling the distribution of plants and vegetation at Prudhoe Bay. With a reasonably complete understanding of the controls and dynamics of the Prudhoe ecosystem, we will be able to produce a series of derived or secondary maps. These maps may be viewed as management tools in the development of arctic oil fields. The derived maps will depict subjects such as vegetation productivity; distri- bution of ground ice and drainage patterns, and vegetation susceptibility to such potential hazards as future road construction, water im- poundment, oil spills, and impact of air pollu- tion. After additional areas have been mapped for soils, and as the soil/vegetation correspon- dences are more firmly established, soils maps might be obtained indirectly from vegetation maps. This would certainly be faster than direct- ly mapping soils, which at the moment requires considerable field labor. Maps could be made to show wildlife distribution and range utilization; such maps could be used to suggest which areas could be set aside for wildlife feeding, denning, 90 or nesting and which areas have lesser ecological benefits or costs. Although the speed of the present mapping method is acceptable for our current objectives we, as well as others, are exploring the possibility of using more rapid remote sensing methods such as computer classi- fication and plotting and color enhancement. In these endeavors, our present maps provide excel- lent and essential ‘‘ground truth.” At the moment, however, it is our experience that automatic techniques cannot successfully pro- duce maps of large areas at scales of 1:3,000 or smaller because of the mosaic and patterning which makes each tundra landscape unit unique. Conclusions We have presented a vegetation map of a small portion of the Prudhoe Bay oil field. We believe the method of mapping we have develop- ed is simple, easily taught, reasonably rapid, and effective. From these maps, with the addition of simple field observations and measurements and with subsequent analysis, it will be possible to develop recommendations for the effective man- agement and husbandry of the tundra ecosystem at Prudhoe Bay. The permanent plots which we have established will serve as an important base- line against which the effects of the develop- ment of the oil field on the tundra ecosystem can be gauged. Acknowledgments We wish to acknowledge the many fruitful discussions we had with Dr. Kaye R. Everett, who produced the soils map which serves as a companion to our vegetation map. We thank John Batty, who acted as field assistant and gave unflaggingly of his expertise in tundra plant identification and vegetation mapping. Ms. Vicki Dow provided us with valuable drafting help in the production of the maps and figures. We would also like to thank Dr. Jerry Brown, Director of the Tundra Biome, who encouraged us to do this work; the Naval Arctic Research Laboratory at Point Barrow and Mukluk Freight Line at Prudhoe Bay, which provided field sup- port. The late Scott Parrish provided us with coordination background information on Prud- hoe Bay. The mapping project was primarily financed from Prudhoe Bay Environmental Sub- committee funds through a subcontract from the Tundra Biome Center, University of Alaska, to the University of Colorado. However, consid- erable degree of effort from the NSF Tundra Biome grant (GV-29350) to the University of Colorado was provided as similar efforts were under way on the Barrow site. References Britton, M. E. (1967). Vegetation of the Arctic tundra. Pages 67-130 jn Arctic Biology (H. P. Hanson, ed.). Oregon State University Press. Brown, J. (1969). Soils of the Okpilak River region, Alaska. Pages 93-128 in The periglacial environment, past and present (T. L. Péwe, ed.). McGill-Queen’s University Press. Brown, J., R. K. Haugen, and S. Parrish (This volume). Selected climatic and soil thermal characteristics of the Prudhoe Bay region. Type 8 vegetation of active frost boils with little vegetation as a result of disturbance by road construction equipment. Carey, K. L. (1972). Classification, mapping and measurement of the distribution of micro- relief from airphotos: Barrow, Alaska. Pages 17-27 in Terrain and coastal conditions of the Arctic Alaskan Coastal Plain; Arctic envi- ronmental data package supplement 1. P. V. Sellman, K. L. Carey, C. Keeler, A. D. Hart- well. USA CRREL Special Report 165, Han- over, New Hampshire. Everett, K. R. (This volume). Soil and landform associations at Prudhoe Bay, Alaska: A soils map of the Tundra Biome area. Kuchler, A.W. (1967). Vegetation Mapping. Ronald Press, New York, 422 pp. Matveyeva, N. V., T. G. Polozova, L. S. Blago- datskyh, and E. V. Dorogostaiskaya (1973). A brief sketch of the vegetation in the region of the Taimyr Biogeocoenological Station. Pages 7-49 jin Biogeocoenoses of Taimyr tundra and their productivity (B.A. Tikhomirov and N.V. Matveyeva, eds.). Nauka, Leningrad, vol. 2. (Available as Tundra Biome translation.) Murray, B. M. and D. F. Murray (This volume). Provisional checklist of the vascular, Manuscript submitted January 1974. 91 bryophyte, and lichen flora of Prudhoe Bay, Alaska. Neiland, B.J. and J. R. Hok (This volume). Vegetation survey of the Prudhoe Bay region. Polunin, N. (1948). Botany of the Canadian Eastern Arctic, Part Ill; Vegetation and ecology. National Museum of Canada Bull. 104, 304 pp. Rastorfer, J. R., H. J. Webster, and D. K. Smith (1973). Floristic and ecological studies of bryophytes of selected habitats at Prudhoe Bay, Alaska. The Ohio State University Institute of Polar Studies, Report No. 49, 20 pp. White, R. G., B. R. Thomson, T. Skogland, S. J. Person, D. E. Russell, D. F. Holleman, and J. R. Luick (This volume). Ecology of cari- bou at Prudhoe Bay, Alaska. Wiggins, |. L. (1951). “‘The distribution of vascu- lar plants on polygonal ground near Point Barrow, Alaska.’ Contr. Dudley Herbarium, Stanford University Press, 318 pp. O2 4 # o « 4 ¢ 5 F ; Institute of Acricubtiral Sciences, Transplant garden with pingo in background at Prudhoe Bay. University of Alaska 93 Responses of Arctic, Boreal, and Alpine Biotypes in Reciprocal Transplants WILLIAM W. MITCHELL and JAY D. McKENDRICK Institute of Agricultural Sciences University of Alaska Palmer, Alaska 99645 Introduction Transplant gardens were established in 1972 at Prudhoe Bay (arctic site, Fig. 1) and Palmer (boreal site, Fig. 2) in Alaska. Responses of perennial plants obtained from arctic, boreal, and temperate locations were compared when grown under relatively uniform conditions at these two northern sites. Forty different biotypes in six grass species from locations in Alaska and Colorado were entered in the study. An additional study was conducted in 1972 and 1973 at both sites comparing 1 year’s growth of seeded materials in phytometers. This report sums the results obtained in the transplant study through the 1974 growing season. Transplant Study Procedures Each biotype included in the transplant study was subdivided for pre-establishment in the greenhouse prior to transplanting in the field. Round pots, 33 cm across and 20 cm deep, were filled with a mica peat mix and placed in holes dug about 25 cm deep in the two gardens. The plants were transplanted into these pots in the Palmer garden on June 13, 1972 and into the Prudhoe garden (Fig. 3) on June 18, 1972. Each pot was fertilized with a mix supplying N, P, and K at the rate of 45, 79, and 74 kg ha’! respectively, at the time of transplant and again at the start of the 1974 growing season. The plants were watered in the Palmer garden as needed. No watering was necessary in the Prud- hoe garden. Measurements were conducted in mid- August in the Palmer garden and late August in the Prudhoe garden. The earlier measurements were necessary in the Palmer garden because of earlier maturing dates at the boreal site. Two plants of each accession were measured for the following characteristics: 1. median height to nearest cm of taller growing leaves when extended; 2. median height to nearest cm of taller growing culms; 3. median width to nearest mm of most typical leaves; 4. number of flowering culms; 5. extent of basal spread in cm; 6. density of shoot growth judged accord- ing to 5 classes (1-5; sparse to dense); 7. weight of shoots clipped off at ground level and oven-dried at 60° C., and 8. oven-dry weight of roots (attempted but abandoned for reason given below). 94 2 } Transplant { < O_S Deadhorse Airfield ag 149°00' 148°40' 148°20' Fig. 1. Prudhoe Bay area with location of transplant garden. Measurements of two plants of each accession were averaged for each character. Periodic observations were made of flower- ing times (anthesis) in the Palmer garden. Flowering material was examined at the end of the season for the production of seed, but no quantitative measure was obtained of seed pro- duction. An effort to obtain root weights was pre- vented by the nature of the mica peat growing medium. It was impossible to separate the mica peat from the mass of root material developed in the second season by the perennial plants with- out losing an unknown but significant quantity of root material in the washing process. Following are the origins, elevations, and habitat information for the transplant entries. Locations of the collection sites for the. Alaskan entries are denoted in Fig. 2. Alopecurus alpinus Alaska: Accession No. 126— Barrow; 15 m; arctic tundra No. 134 & 135— Prudhoe Bay; 15 m; arctic tundra No. 136— Atigun Canyon; 910 m; arctic tundra No. 129— Fort Yukon; 140 m; boreal, riverbank No. 137— Anchor R., Kenai Peninsula; 245 m; coastal forest, meadow Colorado: No. 130 & 131— Summit Lake; 3910 m; alpine meadow Deschampsia caespitosa (sensu lato) Alaska: Accession No. 138— Meade River; 15 m; arctic tundra No. 142— Prudhoe Bay; 15 m; arctic tundra No. 147— Franklin Bluffs; 90 m; arctic, river bluff No. 143 & 144— Caribou Mt.; 670 m; alpine tundra No. 145 & 146— Copper Center; 350 m; boreal, riverbank No. 148— Turnagain Pass; 300 m; subalpine meadow Colorado: No. 140— Niwot Ridge; 3600 m; alpine meadow No. 141— Summit Lake; 3910 m; alpine meadow No. 139— Rollins Pass; 3555 m; alpine meadow 95 Arctagrostis latifolia Alaska: Accession No. 155 & 156— Prudhoe Bay; 15 m; arctic tundra No. 154— Eagle Summit; 1130 m; alpine tundra No. 149, 150 & 151— Tok Junction; 490 m; boreal forest, bog No. 153— Eureka; 1110 m; low alpine shrub community No. 154— Hatcher Pass; 855 m; alpine tundra Calamagrostis inexpansa Alaska: Accession No. 158, 159 & 162— Sagwon; 200 m; arctic, riverbank No. 164— Galbraith Lake; 855 m; arctic, riverbank No. 160— Dietrich Valley; 425 m; subarctic riverbank No. 161 & 165— Glennallen; 610 m; boreal, bog No. 163— Palmer, near sea level; boreal, tidal flats Festuca rubra Alaska: Accession No. 166— Franklin Bluffs; 90 m; arctic, river bottom No. 168— Sagwon; 200 m; arctic, river bottom No. 167— McKinley Park; 1070 m; alpine tundra No. 169— Anchor R., Kenai Peninsula; 245 m; coastal forest, meadow Poa alpina Colorado: Accession No. 157— Niwot Ridge; 3600 m; alpine meadow Results Flowering culm production was highly vari- able among both the arctic and boreal entries within species. Most of the arctic entries increas- ed in flowering culm production at both gardens in the second and third growing seasons. Many of the boreal entries declined in number of flowering culms at Palmer in the third season, particularly if they had produced a large number in the preceding season. Most of the boreal entries succeeded in flowering at Prudhoe, but many produced very few culms. A few were 96 Meade River e prodhoelBay @ @ Franklin Bluffs @ Sagwon Galbraith Lake Atigun Canyon @ Dietrich Valley \ Caribou Mountain@® @ Fort Yukon @ Eagle Summit ALASKA \ McKinley Park @ @ Tok Junction Eureka Glennallen Hatcher Pass @ SO Copper Center Palmer may eS Turnagain Pass @ Anchor River yy? Fig. 2. Map of Alaska with locations of transplant gardens (denoted by arrows) and collection sites for plant materials entered in transplant study. remarkably prolific. Some of the arctic entries produced more flowering culms at Palmer than at Prudhoe. Shoot weights generally were greater at Palmer, but leaves often were longer at Prudhoe, particularly in the third year. As a rule, leaves were slightly to considerably wider at Prudhoe. Plants generally spread more in basal growing area at Palmer. No definite patterns were reflected in the performances of the different polyploid races. More detailed discussions of performances by species follows. Morphological and other data are presented in Table 1. Alopecurus alpinus The Colorado entries winter-killed at Prud- hoe while surviving at Palmer. The Alaskan entry from the Kenai Peninsula was severely winter injured at Prudhoe. The north to south gradient in collection sites for this species was reflected in plant height (or leaf lengths) in the experimental gardens (Fig. 4). Plants from the more southern loca- tions in Alaska grew taller at both Palmer and Prudhoe. However, shoot heights of the Colo- rado entries were less than that of the south- central Alaska entry at the Palmer site. Those relationships did not hold true for the other parameters. Some of the arctic entries were as productive in shoot weight as the boreal and Colorado entries at Palmer and Prudhoe. The arctic entries produced a short, dense growth at the boreal site and a decidedly taller growth at the arctic site. The plants had spread throughout the pot at both sites, but generally grew less dense at Prudhoe. This was consistent with results obtained in 1973. Two plants of the Kenai Peninsula entry recovered sufficiently from winter injury to produce seed heads in 1974, which grew the tallest at the Prudhoe site followed by an entry from a northern boreal station (Fort Yukon). The plants in the Prudhoe garden bore wider leaves than those in the Palmer garden, as they did in 1973. Three of the arctic entries produced from about two to almost five times as many flower- ing culms as the other entries in both the Palmer and Prudhoe gardens (Fig. 5). This represented a tremendous increase in flowering culm produc- tion from the previous year. One arctic biotype from the Brooks Range (Atigun Canyon) resembled the Fort Yukon entry more than the coastal arctic forms in flowering culm produc- tion. The arctic and boreal entries generally differ- ed little in shoot weights (Fig. 6). All of the entries except the Barrow entry produced more top growth at the boreal site than at the arctic site. A Prudhoe Bay biotype and Fort Yukon biotype were the highest producers at both sites. The arctic biotypes compensated for their short- er growth with the production of more flower- ing culms and generally a more dense growth to yield as much as the boreal types. Deschampsia caespitosa The three Colorado entries and one from the Kenai Peninsula (Turnagain Pass) in southcentral Alaska, all tetraploids, winter-killed at both sta- tions in 1973. An octoploid boreal entry from the southern interior region of Alaska (Copper Center) was severely winter injured in the Palmer garden in 1974. The arctic and alpine entries grew shorter at Palmer than they did at Prudhoe, which general- ly was consistent with results obtained in 1973 (Fig. 7). The single boreal entry (IAS 145, Cop- per Center) that survived in both gardens grew considerably taller than the other entries at Palmer. The boreal entry grew longer leaves but shorter and much fewer flowering culms at Prudhoe than it did at Palmer. The arctic and alpine entries increased appre- ciably in flowering culm production over the previous year at Prudhoe (Fig. 8). The tetraploid boreal entry (Copper Center, 145) declined in 97 OOOO OMOGOOOG ae, 168 166 COOOOSOOOOD pimes lOOO00 800000 164 162 [00000 200000] —N— lOOO0O0sO00000 160 158 OCOCO008OOCOCO0O 156 COO005 00000 154 OCOO0005 OO0CO0O DO O000 200000 152 OOOOOsZO0000 150 148 OO000# COOO0O0 146 OO000# 00000 OOO000#00000 144 143 [DOO 00 FO0000 OOOOOFO0000 142 = 142 OOOO00F 00000 141 OO000z00000 OO000 00000 141 OOO000F 00000 140 140 OO000F 00000 138 OO000 800000 138 OOO0008 OO000 n"MOOOOO8 OOOO0O0 nIOOCOOOO0® OO000 NIOOOOOSOO00O00 "OOOO00 s OOO00 30 0OO0O08 OO0O0O "IO OOOO 8OOO00 MOOOO0s OO000 PLOOCS x OOO00 OOO OO 8 OOOO0O} TAS IAS Fig. 3. Plan of transplant garden at Prudhoe Bay. 98 Table 1 Morphological, cytological, flowering, and biomass data on grasses grown in transplant gardens at Palmer (Pa) and Prudhoe (Pr), 1974 results. Entries are ordered along general north to south gradient within each species according to origin. No. of Total Acc. Ht (cm) Leaf width Flw. culms Basal width * dry weight Species & Origin (2n No.) No. Leaf/Culm (mm) per plant (cm) of top growth Pa Pr Pa Pr Pa Pr Pa Pr Pa Pr Alopecurus alpinus Alaska: Barrow (c. 102) 126 5/9 13/30 3.0 4.0 Sf 114. 82/40 32/40 186 135 Prudhoe Bay (c. 100) 134 10/13 +=14/29 3.0 50 146 126 32/45 382/25 368 215 Prudhoe Bay (c. 100) 135 10/13 13/26 4.0 40 127 94 32/40 32/20 284 15.0 Atigun Canyon (c. 114) 136 Misid 20/33 35 4.5 54 30 32/35 32/3.0 247 15:5 Ft. Yukon (98) 129 17/34 25/40 S13) 6.0 27 40 29/45 32/25 388 195 Kenai Peninsula (98) 137 31/61 36/52 3.0 7.0 31 7 30/30 24/15 30:3 10:5 Colorado: Summit Lake (c. 104) 130 23/46 Xx 3:5 Xx 18 X 32/3.0 Xx 28.9 Xx Summit Lake (c. 105) 131 22/43 Xx 4.0 Xx 15 x 30/3.0 x 29.3 x Deschampsia caespitosa Alaska: Meade River (26) 138 14/20 25/31 3.0 3.0 43 49. 15/50 10/50 354 35.0 Prudhoe Bay (52) 142 12/22: 19/30 2.0 2.0 65 194 16/50 12/50 89.5 40.0 Franklin Bluffs (52) 147 14/28 21/39 a5 3.0 95 120. 14/50 12/50. 497 425 Caribou Mt. (26) 143 9/30 16/30 2.0 2.0: 131 112. 14/50 11/50 2351 31.5 Caribou Mt. (52) 144 11/28 15/28 2.0 2,5 74 ‘92 10/5.0 9/5.0 18.9 25.0 Copper Center (26) 145 19/67 27/32 25 3.0 45 8 12/35 9/5.0 25.4 9.0 Copper Center (52) 146 XX 16/31 XX 2.0 XX 120 XX 13/5.0 XX 34.5 Turnagain Pass (26) 148 DEAD Colorado: Niwot Ridge (26) 140 DEAD Summit Lake (26) 141 DEAD Rollins Pass (26) 139 DEAD Arctagrostis latifolia Alaska: Prudhoe Bay (56) 155 19/36 24/35 6.0 9.0 13 15. 2.22/1.0) 222/25 3:2 8.5 Prudhoe Bay (28) 156 XX 24/31 XX 8.5 XX 53 XX 32/2.0 XX 22.5 Eagle Summit (56) 154 32/52 27/42 9.0 8.5 25 16.32/10" 26/30 A429 140 Tok Junction (28) 149 XX 45/40 XX 9.0 XX 8 XX 32/2.0 XX 14.0 Tok Junction (56) 150 40/70 34/27 12:0. 12:0 22 ZL. 31/30 32/3.0.7. 554 8.0 Tok Junction (42) 151 40/74 x 10.0 x 22 x 32/2.0 x 32.2 x Eureka (28) 15s 32/57. 26/31 AS 9.0 39 2. St/2.0 25/20. 2 359 ous) Hatcher Pass (28) 152 32/60 32/38 60 11.0 24 % 82/30 24/25 , sis 8.5 Calamagrostis inexpansa Alaska: Sagwon (63) 158 18/36 41/44 3.0 6.0 28 18. 32/20 22/40 . 21.2 320 Sagwon (56) 159 20/39 31/0 3.5 6.0 33 2°. 32/725 32/2.0 — 374 8.0 Sagwon (28) 128 16/35 29/28 2.0 40 116 13 30/25 327/30 280 195 oh) Table 1 (continued) No. of Total Acc. Ht (cm) Leaf width Flw. culms Basal width” dry weight Species & Origin (2n No.) No. Leaf/Culm (mm) per plant (cm) of top growth Pa Pr Pa Pr Pa Pr Pa Pr Pa Pr Calamagrostis inexpansa Alaska: Galbraith (28) 164 18/39 38/36 25 4.5 46 20 | 32/30) 32/2:0, | 35:3 18.5 Dietrich Valley (42) 160 30/54 44/42 4.0 6.0 68 9 19/40 26/2.00 28.2 17.0 Glennallen (28) 161 24/53 23/0 3.0 35 98 0. 31/30 2 28/20 49:9 55 Glennallen (42) 165 27/54 34/0 35 7.0 72 0). 32/15 | 26/20" 44.0 7.0 Palmer (105) 163 38/57 XX 4.0 XX 61 XX 30/3.5 XX 63.9 XX Festuca rubra Alaska: Franklin Bluffs (42) 166 15/22 15/23 2.5 2.5 2 iL 223/385 8/5.0 19.7 3.5 Sagwon (42) 168 8/39 12/24 25 Dol 34 5 14/45 7/4.5 17.1 1.0 McKinley Park (42) 167 15/34 16/27 2.0 2.0 21 28° 27/35 9/5.0 23.4 5.0 Figure preceding slash (/) is basal width (cm); figure following slash is density estimate of basal growth judged accord- ing to 5 classes (1-5, sparse to dense). X Dead XX ** Seriously injured or unhealthy flowering culm production at both sites while the octoploid (Copper Center, 146), winter injured at Palmer, increased at the Prudhoe site. The octoploid boreal entry produced many more flowering culms at Prudhoe than the tetraploid originating from the same location (Copper Center). The arctic octoploids also were considerably more productive in flowering culms than the arctic tetraploid. However, the alpine tetraploid from Caribou Mountain outproduced, by a smaller margin than the above instances, the octoploid from the same location. The two arctic entries from Prudhoe Bay and Franklin Bluffs yielded the most top growth at both sites (Fig. 9). This was consistent with 1973 results. The tetraploid boreal entry declin- ed significantly in top growth from the previous year at both sites. Arctagrostis latifolia A boreal entry died in the arctic garden during the first year. An arctic entry and a boreal entry did very poorly in the Palmer garden and were omitted from the analysis Grazing prevented accurate determination; believed not to have produced any culms. there. A boreal entry which recovered from an unhealthy start that excluded it from analysis in 1973 was included in the 1974 analysis. The alpine and boreal biotypes grew taller (Fig. 10), bore more flowering culms (Fig. 11), and produced much more shoot weight (Fig. 12) than the surviving arctic biotype in the Palmer garden. The boreal entries produced longer leaves but fewer flowering culms than the arctic entries at Prudhoe. An arctic tetraploid entry produced the most flowering culms and top growth in the arctic garden. A boreal octoploid yielded the most top growth at Palmer. The boreal entries from central to southcentral Alas- ka grew more densely than the more northern entries at Palmer. Shoot weights and numbers of flowering culms were much greater at Palmer than at Prudhoe for most of the boreal entries. The arctic entries increased in number of flower- ing culms in both gardens and increased in shoot weight in the arctic garden in the third season, whereas the boreal entries were variable in this regard. Leaf lengths decreased in the third season. 100 ALOPECURUS ALPINUS — LEAF LENGTHS ORIGIN: BARROW PRUDHOE ATIGUN FORT KENAI SUMMIT CANYON YUKON PENINSULA LAKE 60 55 50 45 40 35 30 25 e——~ Palmer Transplant Garden O—- — —O Prudhoe Transplant Garden CM 72 73 74 72 73 74 YEARS Fig. 4. Leaf lengths of Alopecurus alpinus jn the Palmer and Prudhoe transplant gardens over 3-year period. 7/Entry severely injured or winter-killed. ALOPECURUS ALPINUS — NO. OF FLOWERING CULMS ORIGIN: BARROW PRUDHOE ATIGUN FORT KENAI SUMMIT CANYON YUKON PENINSULA LAKE >120 4 120 110 100 90 80 70 60 50 40 30 20 »———— Palmer Transplant Garden o——-o Prudhoe Transplant Garden BITE 72 73 74 YEARS Fig. 5. Flowering culm production of Alopecurus alpinus over the 3-year period. #/Entry severely injured or winter-killed. An alpine entry from northern interior Alas- ka (Eagle Summit) appeared the most ecological- ly plastic in being second in shoot weight and flowering culm production in both gardens in 1974. Calamagrostis inexpansa A boreal entry was severely winter injured in the arctic garden in 1974 and was excluded from the analyses at that site. All other entries were analyzed at both sites. The boreal entries of northern reedgrass grew taller than the arctic entries at Palmer; results were mixed at Prudhoe (Fig. 13). In most cases leaf growth was longer and wider at Prud- hoe than at Palmer, whereas flowering culms were longer at Palmer. Two of the boreal entries from southern interior Alaska failed to produce flowering culms at Prudhoe. An arctic entry might have been denied flowering through graz- ing activity. Flowering culm production was much more abundant at Palmer than at Prudhoe (Fig. 14). Except for one arctic entry, shoot weights were also greater at the boreal site (Fig. 101 15). In most cases, the rhizomatous grass spread throughout much of the growing area within the pots at both sites. A nine-ploid entry produced the most top growth at Prudhoe, while a 15-ploid boreal (tidal flat) entry was the highest yielder at Palmer. Arctic and boreal tetraploids were the most prolific flowering culm producers at Palmer in the third season. A northern boreal hexaploid was outstanding in the second year but declined in the third year. All entries decreased in leaf length in the third season at Palmer, as did most of the boreal entries at Prudhoe. Most of the arctic entries increased in leaf length, shoot weight, and flowering culm production at Prudhoe and in number of flowering culms at Palmer in the third season. They showed little improvement in shoot weight at Palmer. The boreal entries de- creased in shoot weight and number of flowering culms at Prudhoe. Most of them increased in culm production at Palmer, but results were mixed in shoot weights. ALOPECURUS ALPINUS — SHOOT WEIGHTS ORIGIN: BARROW PRUDHOE ATIGUN : CANYON 60 36 *——~ Palmer Transplant Garden 0-—--9 Prudhoe Transplant Garden 72 73 FORT YUKON KENAI PENINSULA SUMMIT LAKE ° 74 72 73 74 YEARS Fig. 6. Shoot weights of Alopecurus alpinus over 2- or 3-year period. 7/ Entry severely injured or winter-killed. 102 DESCHAMPSIA CAESP/ITOSA—LEAF LENGTHS FRANKLIN y ORIGIN: MEADE R. PRUDHOE BLUFFS CARIBOU MT. CARIBOU MT. COPPERIG: COPPER C. (2n = 26) (2n = 52) (2n = 52) (2n = 26) (2n = 52) (2n = 26) (2n = 52) @-----9 Prudhoe Transplant Garden o—- Palmer Transplant Garden 1972 73 74 72 73 74 72 73 74 72 73 74 72 73 74 72 73 YEARS Fig. 7. Leaf lengths of Deschampsia caespitosa over the 3-year period. 4/ Entry severely injured or winter-killed. DESCHAMPSIA CAESP/TOSA—-NO. OF FLOWERING CULMS FRANKLIN ORIGIN: MEADE R. PRUDHOE BLUFFS CARIBOU MT. CARIBOU MT. COPPER C. COPPER C. (2n = 26) (2n = 52) (2n = 26) (2n = 52) ~120 J 120 110 100 90 80 70 60 50 40 30 20 10 i 1972 73 74 72 73 74 72 73 74 72 73 74 72 73 74 72 73 74 72 73 74 YEARS o—————+ Palmer Transplant Garden o-——--© Prudhoe Transplant Garden Fig. 8. Flowering culm production of Deschampsia caespitosa over the 3-year period. 4/Entry severely injured or winter-killed. Festuca rubra Most of the red fescue entries declined ap- preciably in leaf length (Fig. 16), production of flowering culms (Fig. 17), and shoot weight (Fig. 18) at both sites. A McKinley Park entry yielded the most in shoot weight at both sites and produced the most flowering culms at Prud- hoe. An arctic entry (Sagwon) bore the most flowering culms at Palmer. Poa alpina An entry of Poa alpina from Niwot Ridge, Colorado, became well established in both gardens in the initial year, but was winter-killed during the ensuing winter. Seed set and phenology A small amount of matured seed was found in some entries from the Prudhoe garden in 1973, but none was found in any of the entries in 1974. Only the arctic entries of A/opecurus alpinus, nos. 126, 134, 135, and 136, set seed in 1973. All surviving entries with healthy growth matured in the Palmer garden. 103 Approximate flowering dates (anthesis) were obtained for the entries in the Palmer garden in 1973 and 1974. Arctagrostis Jatifolia was omitted because of poor initial development of many of the plants. Alpine foxtail was the earliest to flower followed by tufted hairgrass, with red fescue and northern reedgrass being the last to flower (Fig. 19). The arctic entries generally commenced flowering about 2 to 3 weeks earlier than the boreal forested region entries and the Colorado alpine entries. The boreal alpine entries as a rule initiated flowering about 5 to 10 days after the earliest arctic entries and sometimes overlapped with their flowering times. The latest flowering entries were the high polyploid biotype of northern reedgrass (no. 163, 2n = 105), from the Cook Inlet tideland flats, and the coastal forest entry of red fescue. Discussion Most of the alpine entries from Colorado perished in the two transplant gardens in Alaska. DESCHAMPSIA CAESPITOSA—-SHOOT WEIGHTS FRANKLIN ORIGIN: MEADE R. PRUDHOE BLUFFS (2n = 26) (2n = 52) (2n = 52) o-—-—-0 Prudhoe Transplant Garden o———~ Palmer Transplant Garden 1972 73 74 72 73 74 72 73 74 72 CARIBOU MT. CARIBOU MT. COPPER C. COPPER C. (2n = 26) (2n = 52) (2n = 26) (2n = 52) ° a/ (oF Ge) 73 74 72 73 74 72 73 74 72 73 74 YEARS Fig. 9. Shoot weights of Deschampsia caespitosa over 2- or 3-year period. 7/ Entry severely injured or winter-killed. 104 ARCTAGROSTIS LATIFOLIA — LEAF LENGTHS EAGLE ORIGIN: PRUDHOE PRUDHOE SUMMIT (2n = 56) (2n = 28) (2n = 56) 65 60 55 @----0 Prudhoe Transplant Garden 50 +——- Palmer Transplant Garden 1972 73 74 72 73 74 72 73 74 72 TOK JCT. (2n = 28) 73 74 72 YEARS TOK JCT. (2n = 56) 73 74 72 TOK JCT. (2n = 42) 73 74 72 Fig. 10. Leaf /engths of Arctagrostis latifolia over 3-year period. 4/ Entry severely injured or winter-killed. ARCTAGROSTIS LATIFOLIA — NO. OF FLOWERING CULMS EAGLE ORIGIN PRUDHOE PRUDHOE SUMMIT (2n; = 56) (2n = 28) (2n = 56) o—» _ Palmer Transplant Garden @-----O Prudhoe Transplant Garden 1972 73 74 72 73 74 72 73 74 72 TOK JCT. (2n = 28) 73 74 72 YEARS TOK JCT. (2n = 56) 73 74 72 TOK JCT. (2n = 42) 73 74 72 Fig. 11. Flowering culm production of Arctagrostis latifolia over 3-year period. 4/Entry severely injured or winter-killed. EUREKA (2n = 28) isi 74 72 EUREKA (2n = 28) 7 ah =O -o 3 74 72 HATCHER PASS (2n = 28) 73 74 HATCHER (2 ye) ah” Seee74 7 PASS n = 28) The two entries of A/opecurus alpinus survived in the boreal garden at Palmer, but winter-killed at Prudhoe. The entries of Deschampsia caespitosa and Poa alpina winter-killed in both gardens. Not all of the Alaska entries thrived in both gardens. A hairgrass biotype from a south- central Alaska subalpine meadow winter-killed in both gardens. A southcentral coastal entry of Alopecurus experienced considerable injury at Prudhoe. Arctic entries of Arctagrostis latifolia had a difficult time at Palmer. As would be expected, production was generally greater at Palmer than at the Prudhoe site. Differences in production between the two sites were often greater for the boreal entries than the arctic entries. Greater dry weights at Palmer were due to more abundant tillering and, in most cases, flower culm production. The hairgrass entries, however, tended to converge in dry weight production at the two sites in the third year. Though dry matter production was generally greater at Palmer, leaves tended to grow longer and wider at Prudhoe. In some cases leaves were appreciably wider at the arctic site. This prob- ably can be attributed to longer photoperiods with lower evaporative stresses in the Arctic. The degree to which arctic limitations on growth also restrict the effective range of genetic 105 variability and plasticity of plants requires clari- fication. Mosquin (1966) and Savile (1972) pro- posed that members of the arctic flora are genetically uniform. Such constancy was thought to be an inevitable consequence of means adapted by plants to speed up seed production. Bocher (1963) observed, however, that ‘‘...all species are more or less variable...” In this study a great deal of variability was expressed in the number of flowering culms and amount of top growth produced. For example, shoot weights of arctic biotypes of Deschampsia caespitosa ranged from 40g to almost 90g at Palmer in 1973, and from 35g to 90g in 1974. Production at Prudhoe varied from 10g to 40g in 1973, but only from 35g to 43g in 1974. Variability in flowering culm production was even greater for these entries — from 3 to 106 at Palmer and 3 to 62 at Prudhoe in 1973, and from 43 to 95 at Palmer and 49 to 194 at Prudhoe in 1974. The boreal entries of hairgrass also varied a great deal in their performance at both sites, as did entries of other species. The study has provided some information on the phenotypic plasticity of northern ecotypes. Plasticity in metabolic reactions with tempera- ture has been demonstrated in arctic and alpine ecotypes of Oxyria digyna (Billings et al. 1971). ARCTAGROSTIS LATIFOLIA — SHOOT WEIGHTS EAGLE HATCHER ORIGIN: PRUDHOE PRUDHOE SUMMIT TOK JCT. TOK JCT. TOK JCT. EUREKA PASS (2n = 56) (2n = 28) (2n = 56) (2n = 28) (2n = 56) (2n = 42) (2n = 28) (2n = 28) 55 Palmer Transplant Garden 50 O---—-O Prudhoe Transplant Garden 45 40 35 2°30 25 20 15 ug -.) Pp 5 Onn ah 1972 73 74 72 73 74 72 73 74 72 73 74 72 73 74 72 73 74 Fig. 12. Shoot weights of Arctagrostis latifolia over 2-year period. severely injured or winter-killed. YEARS 4/ Entry 106 CALAMAGROSTI/S INEXPANSA—LEAF LENGTHS GALBRAITH DEITRICH ORIGIN: SAGWON SAGWON SAGWON LAKE VALLEY GLENNALLEN GLENNALLEN PALMER (2n = 63) (2n = 56) (2n = 28) (2n = 28) (2n = 42) (2n = 28) (2n = 42) (2n = 105) 1972 73 74 72 73 74 72 73 74 72 73 74 ee fs 74 72 73 74 72 73 74 72 73 74 YEAR —— Palmer Transplant Garden Oo —--0 Prudhoe Transplant Garden Fig. 13. Leaf lengths of Calamagrostis inexpansa over 3-year period. 4/ Entry severely injured or winter-killed. CALAMAG ROSTIS INEXPANSA—NO. OF FLOWERING CULMS GALBRAITH DIETRICH ORIGIN: SAGWON SAGWON SAGWON LAKE VALLEY GLENNALLEN GLENNALLEN PALMER (2n = 63) (2n = 56) (2n = 28) (2n = 28) (2n = 42) (2n = 28) (2n = 42) (2n = 105) hm f f 7 ~o Sari mie ual! 1972 73 74 72 73 74 72 73 74 72 73 74 72 73 74 72 73 74 72 73 74 72 73 eo—— Palmer Transplant Garden oO----o Prudhoe Transplant Garden 120 110 100 a 2 b/ 74 YEARS Fig. 14. Flowering culm production of Calamagrostis inexpansa over 3-year period. 7/ Entry grazed but believed not to have produced culms. b / Entry severely injured or winter-killed. Some of the arctic entries in this study manifest- ed considerable latitude in adaptations to the boreal site, with many of them achieving appre- clably greater shoot weight and flowering culm production at Palmer than at Prudhoe. This agrees with the responses obtained by Clausen et al. (1940) and Mark (1965) when growing alpine biotypes at lower altitude stations. But these workers also found increased growth in height at the lower, less severe sites, whereas in our study all of the arctic entries grew taller in the Prudhoe garden. Some of them produced a dense but very short growth at Palmer. The alpine entries varied in their adaptive responses to the two sites, but generally appear- ed suited to both. Two alpine biotypes of Deschampsia from northern interior Alaska grew taller at Prudhoe than at Palmer in the third year, but alpine biotypes of the other species from more central and southcentral Alaska grew taller and were more productive in the Palmer garden. Some alpine biotypes of arcticgrass, hairgrass, and red fescue from interior Alaska performed well in both the Palmer and Prudhoe gardens. However, alpine entries of hairgrass from southcentral Alaska and Colorado were unadapted to either site, failing to survive the first winter. The two arctic entries of Arctagrostis appeared to be the most adversely affected in 107 transplanting to the boreal region. They experi- enced difficulty in establishing at Palmer in their first year, and one of the entries eventually succumbed. This may indicate a genotype that is more narrowly adapted to the arctic environ- ment, with less plasticity than the others. These results have some practical signifi- cance in the possible application of native plant materials in various regions of Alaska. Those materials with sufficient plasticity to perform well in non-agricultural areas where they may be needed for rehabilitation, and in an agricultural area where they could be grown for seed, offer good potential for practical applications. In red fescue, for instance, a non-arctic entry of alpine origin was the best performer of that species both at Prudhoe and Palmer, thus pointing to the possibility of alpine entries being the source of material for tundra uses over a wide latitude. The relative merits of local vs. non-local seed sources were assessed in an altitudinal transect study with Pinus ponderosa (Conkle 1973). In that study, seed of yellow pine from a select zone outperformed local seed sources at alti- tudes lower and higher than that zone. The diverse environments, particularly as they involved different altitudes, along the lati- tudinal transect sampled in Alaska confounded the delineation of ecoclinal gradients for most entries. However, such a gradient was rather CALAMAG ROSTIS INEXPANSA—SHOOT WEIGHTS GALBRAITH SAGWON LAKE (2n = 28) ORIGIN: SAGWON SAGWON (2n = 63) (2n = 56) (2n = 28) o+——— Palmer Transplant Garden O©——-o Prudhoe Transplant Garden 1972 73 74 72 73 74 72 73 74 72 73 DIETRICH VALLEY GLENNALLEN GLENNALLEN PALMER (2n = 42) (2n = 28) (2n="42) (2n = 105) Ie Bat OL \v/ ~o 73 73°«74 74 72 73 74 72 73 74 72 74 72 YEARS Fig. 15. Shoot weights of Calamagrostis inexpansa over 2-year period. 7/ Entry grazed. D/En try severely injured or winter-killed. 108 FESTUCA RUBRA—LEAF LENGTHS McKINLEY SAGWON PARK FRANKLIN ORIGIN: BLUFFS *——~ Palmer Transplant Garden @----0 Prudhoe Transplant Garden YEARS Fig. 16. Leaf lengths of Festuca rubra over 3- year period. FESTUCA RUBRA-—NO. OF FLOWERING CULMS FRANKLIN ORIGIN: BLUFFS McKINLEY SAGWON PARK YEARS o——— Palmer Transplant Garden O--- Prudhoe Transplant Garden Fig. 17. Flowering culm production of Festuca rubra over 3-year period. clearly evident in the height development of Alopecurus alpinus. The shortest forms in both gardens originated in the coastal tundra region followed by the Brooks Range entry, northern interior biotype, and Kenai Peninsula entry, in order of increasing heights. The Kenai Peninsula entry of this species resembled the Colorado entries more than the other Alaskan entries. The Colorado and southcentral Alaska entries grew tall, spread rather loosely from a dense central tuft at Palmer, and adapted poorly to the arctic site. The other Alaskan entries produced a more dense and shorter growing mat of material at Palmer and grew well at Prudhoe. The south- central coastal material of Alaska may be more closely related to the alpine forms of the Rocky Mountains than to the northern Alaskan material. No apparent conclusions can be drawn from the study regarding the possible significance of different ploidy levels within a species. In Deschampsia the diploid (2n = 26) appeared somewhat superior in both gardens to the tetraploid (2n = 52) collected from an alpine site on Caribou Mountain. However, the tetraploid race from Copper Center outperformed the diploid race from there in the arctic garden, whereas at Palmer the reverse was true. The FESTUCA RUB RA—SHOOT WEIGHTS McKINLEY SAGWON PARK FRANKLIN ORIGIN BLUFFS -———~ Palmer Transplant Garden o-— --o Prudhoe Transplant Garden Fig. 18. Shoot weights of Festuca rubra over 3-year period. 109 ANTHESIS DATES MAY JUNE JULY 1973 oO O &—A Aa Alopecurus = es BP ea as ae = — eee ee ES —— alpinus 1974 o—oO O a 4A 1973 OS Deschampsia wets caespitosa wa 4 =x = _ a i i ae 1974 O—O @—@ Oa/ 1973 2 eeeeaecrens "| A Calamagrostis ie eee ee. O O inexpansa ae St 1S a Nee pike 4 1974 o—_) Aa/ QL 0 1973 Se A Festuca fone WE pa ® rubra a ie eee a eae cs aw =p, = 1974 ——r A a/ O Arctic biotypes O Boreal, forested biotypes ® Boreal, alpine biotypes LZ Boreal, coastal biotypes A Colorado alpine biotypes 9/Anthesis occurred after June 20; specific dates not obtained after that date in 1974. Fig. 19. Anthesis dates of transplant entries in Palmer garden in 1972 and 1973 organized according to type of origin. highest polyploid in Ca/amagrostis inexpansa grew the most at Palmer but failed at Prudhoe. Extensive sampling and testing at the population level would be necessary to better define dif- ferences related to ploidy levels. A comprehensive transplant study involving populations of Agrostis tenuis led Bradshaw (1959) to emphasize the roll of small popula- tions interacting with their particular environ- ment to produce local differentiation. He found natural selection effective in distinguishing populations occupying habitats very short dis- tances apart. Though conditions in the North, particularly in the Arctic, are thought to limit differentiation in favor of systems that maintain successful genotypes, the results obtained in this study suggest greater variability than is suspect- ed. Conclusions drawn from the performance of only one or a few genotypes out of a given population must be guarded, but it is possible that interactions of local populations with their environments are producing significant differ- entiation. Such differentiation would result ina flora better able to meet future exigencies than were it genetically uniform. Phytometer Study Procedures Three species were grown from seed in plas- tic pots, 20cm across and 21cm deep, filled with a mica peat mix and sunk to ground level at Palmer and Prudhoe in 1973. Seed of ‘‘Engmo” timothy, annual ryegrass, and ‘‘Sprite’’ peas were sown on the surface of the mix on June 26 at both sites. The pots were fertilized about every week with 250 ml of Hoagland solution containing an additional 200 ppm of P. After germination the seedlings were reduced to five in each pot. The material was harvested 65 days from planting at Prudhoe and 66 days at Palmer. Various morphological and biomass measure- ments were made. 110 Table 2 Dry matter accumulations in grams per plant (1973 phytometer) of whole plant, and shoot and root components for Sprite pea, Engmo timothy, and annual ryegrass at Palmer and Prudhoe. Palmer (Boreal) Prudhoe (Arctic) Whole Shoot/Root Whole Shoot/Root Entry Plant Shoot Root Ratio Plant Shoot Root Ratio Sprite pea 9.5 8.4 1A 7.6 1.14 78 36 22. Engmo timothy 74 o5 3.9 9 .046 .026 .020 to Annual ryegrass 18.9 10.7 8.2 is! .352 .187 -165 1.1 Results and discussion Results were consistent with those of 1972 in that annual ryegrass produced the most root and shoot dry matter at the boreal location while Sprite pea was the highest producer at the arctic site (Table 2). Yields at the arctic site were greatly reduced from those at the boreal site. There was a greater reduction in root growth than in shoot growth of timothy, thus resulting in a higher shoot/root ratio at Prudhoe; whereas in the pea, shoot growth decreased considerably more than root growth, thus pro- ducing a lower shoot/root ratio. That ratio remained about the same in annual ryegrass at both sites, as it did in 1972. The grasses pro- duced more root growth than the pea at Palmer, but the reverse was true at Prudhoe. The pea produced less root growth with respect to shoot growth than the grasses at both sites. Total reduction in biomass at the arctic site was much greater for the perennial than the annuals. Sprite pea produced about 9x the biomass at the boreal site than it did at the arctic site; annual ryegrass accumulated about 50x and Engmo timothy about 150x their arctic production. Biomass production of the two annuals at Palmer in 1973 exceeded that of the previous year (Table 3) in spite of a shorter growing period with fewer growing degrees (Table 4). Periodic fertilization with nutrient solution in 1973, as compared with one-time fertilization in 1972, probably accounted for the difference. Apparently the shorter growing period of 1973 was more significant in its effect in the Arctic. There yields were all lower in 1973 despite more abundant fertilization and the accumulation of more growing degrees. Increasing the frequency of fertilizer applications apparently did not influence growth as much where climatic condi- tions severely limited growth from seed. (Figures for the 1972 Eagle Summit phytometer study were included in Table 6 to demonstrate the intermediate position in biomass production of this alpine site). Table 3 Productivity at arctic (Prudhoe) and alpine (Eagle Summit) sites in Alaska as a percentage of production at Palmer, a boreal site, in 1972 and 1973. Sprite Pea Biomass % of Palmer Location (g) Production 1972 Palmer 5.7 100 Prudhoe 22 38.6 Eagle Summit 4.3 75.4 1973 Palmer 9.5 100 Prudhoe 1.1 11.6 Annual Ryegrass Engmo Timothy Biomass % of Palmer Biomass % of Palmer (g) Production (g) Production 10.2 100 8.04 100 6 5.9 .06 a 3.0 29.3 .34 4.2 18.9 100 7.40 100 4 2.1 05). af Table 4 Mean monthly air temperatures (°C) for summer months and growing degrees accumulated above daily mean of 0 C for phytometer growing periods at Palmer and Prudhoe in 1972 and 1973. * Monthly Means Location & Year June July Prudhoe 1972 21° 6.7 1973 2.6 7.8 Palmer 1972 10.9 15.5 1973 11.6 13.8 Phytometer Growing Period No. Growing Aug. Days Degrees 6.4 76 447 13 65 473 13.4 76 1063 11.6 66 852 Monthly means and growing degrees were based on daily means derived from daily maxima and minima obtained at about 2 m above the ground. The Prudhoe data were furnished by the Atlantic Richfield Co. from readings taken at their base camp in the Prudhoe Bay region. ** In all cases except June, 1972 at Prudhoe the monthly mean temperature also equaled the mean number of growing degrees for the month. The average number of growing degrees for June, 1972 at Prudhoe was 2.3. The lower monthly mean temperature was due to 7 days averaging O°C or below. Only Sprite pea matured to the stage of seed production at Palmer. Annual ryegrass produced inflorescences in the emerging to emergent con- dition but did not develop beyond the early flowering stage. Timothy did not flower. None of the species flowered at Prudhoe. Acknowledgments These studies were jointly funded from the Tundra Biome Center, University of Alaska, utilizing both State of Alaska and Prudhoe Bay Environmental Subcommittee funds. Consider- able savings in costs to all projects were accom- plished by combining our Prudhoe schedules with non-Biome sponsored research at Prudhoe. The alpine plant materials from Colorado were kindly furnished by Erik K. Bonde and Maxine F. Foreman, who are conducting a similar study along an altitudinal transect in Colorado. References Billings, W. D., P. J. Godfrey, B. F. Chabot, and D. P. Bourque (1971). Metabolic acclimation to temperature in arctic and alpine ecotypes of Oxyria digyna. Arct. and Alp. Res., 3:277-289. Bocher, T. W. (1963). Phytogeography of mid- dle west Greenland. Meddele/ser Om Gron- land, 148:1-289. Bradshaw, A. D. (1959). Population differen- tiation in Agrostis tenuis Sibth. |. Morpho- logical differentiation. New Phyt., 58:208-227. Clausen, J., D.D. Keck, and W.M. Hiesey (1970). Experimental studies on the nature of species. I. Effect of varied environments on western North American plants. Carnegie Inst. of Washington, Pub. No. 520, 452 pp. Conkle, M. T. (1973). Growth data for 29 years from the California elevational transect study of ponderosa pine. Forest Sci., 19:31-39. Mark, A. F. (1965). Ecotypic differentiation in Otago populations of narrow-leaved snow tussock Chionochloa rigida. New Zealand J. Bot., 3:277-299. Mosquin, T. (1966). Reproductive specialization as a factor in the evolution of the Canadian flora. Pages 43-65 in The Evolution of Canada’s Flora (R. L. Taylor and R. A. Lud- wig, eds.). University of Toronto Press. Savile, D. B. O. (1972). Arctic adaptations in plants. Canada Dept. Agric., Monog. 31:1-81. it Oh hiv Animal Investigations its 114 Collecting data on adult insect populations. In the foreground is an emergence trap, used to doc- ument daily emergence of adult craneflies (Tip- ulidae). /n the background, observers examine a “sticky board" trap. David Atwood, USACRREL WAS Keology of Tundra Invertebrates at Prudhoe Bay, Alaska STEPHEN F. MacLEAN, JR. Department of Biological Sciences and Institute of Arctic Biology University of Alaska Fairbanks, Alaska 99701 Introduction Research on tundra invertebrates at Barrow has emphasized three main points: (1) the abun- dance and biomass of invertebrates in various tundra habitats; (2) adaptations of invertebrates to tundra conditions, and (3) their functional role in the tundra ecosystem. The tundra at Prudhoe Bay, while structurally similar to that of Barrow in a number of ways, offers milder summer conditions and a wider variety of habitats than is found at Barrow. Thus, research was planned to extend the observations made at Barrow and to determine the similarity in taxo- nomic structure, abundance, and function of the invertebrate community at the two sites. Obser- vations were made in two seasons, 1971 and 1972. Study Areas Five study plots were selected for intensive study in 1971 in the Prudhoe Bay area. The plots were chosen to provide at least visually homogeneous stands of major topographic- vegetation features of the region. Two study plots (Nos. 4 and 5) were on the drained lake basin that was intensively sampled for primary production data. The remaining three plots were on the elevated bench west of the lake basin. Plot 1: Dryas integrifolia dry heath Plot 2: Carex aquatilis wet swale Plot 3: Dryas integrifolia and graminiform mesic heath Plot 4: Drained lake basin Plot 5: Drained lake basin Vegetational features of this area are reported in greater detail by Webber and Walker (this vol- ume). The above study plots were again sampled in 1972. In addition, two new plots were establish- ed north of drilling pad F. They were selected to avoid any possible influence of human activity and were located on avian study plot C (Norton et al., this volume). Plot 6: Carex aquatilis wet meadow Plot 7: Dryas integrifolia and graminiform mesic heath. Methods 1. Species Diversity. An extensive collec- tion of insects was made in 1971 in an effort to sample all habitats in the Prudhoe Bay area. Identification of specimens by authorities on the various taxonomic groups ts still in progress, and only partial results can be presented at this time. 116 2. Abundance of soil fauna. Four sod cores, each 182.4 cm?, were removed from points chosen at random in each study plot at 10-day intervals in 1971 and 1972. Cores were shipped to Fairbanks, where macroarthropods were re- moved by drying and heating the core under a 60-watt light bulb. Extracted specimens were preserved in alcohol until they could be counted. On 29 August 1972, a set of cores, each 22.9 cm2, was taken from plots 11, 14, 15, 16, and 17. These were brought to Fairbanks where replicate cores were subjected to O’Conner wet funnel extraction for Enchytraeidae and to Macfadyen high-gradient extraction for Acarina and Collembola. Each core was divided into 2.5 cm depth increments to determine distribution of invertebrates with depth below the tundra surface. 3. Phenology. Following a technique used at Barrow (MacLean and Pitelka 1971), two “sticky boards’ (each 1x0.1 m), were placed level with the ground surface on each study plot. The boards were replaced at 3-day intervals. Arthropods captured on the sticky surface were identified and counted under a dissecting micro- scope. Since most arctic insects have a very short adult lifespan, the distribution of ‘‘sticky board” catches through the season corresponds closely with the actual emergence of adult in- sects. The total number of captures in any plot provides an index of abundance that can be used in comparing year-to-year and between-habitat differences. Results 1. Species composition and diversity. Al- though identification of the collection of Prud- hoe Bay insects is far from complete, it is obvious that species diversity is much higher at Prudhoe Bay than at Barrow. For example, collecting in one season produced 13 species of craneflies (two never before collected) at Prud- hoe Bay; collecting in many seasons at Barrow has produced only four species (Table 1). The greatest disparity between Barrow and Prudhoe occurs in the Dolichopodidae (long-legged flies) ; 20 species were collected at Prudhoe Bay in 1971, while the Barrow list has but one species. Prudhoe Bay has at least 12 butterfly species: Barrow has five. This difference is apparently due to higher within-habitat diversity and to the greater variety of habitats available in the Prud- hoe Bay region. David Atwood, USACRREL Adult insects captured on “sticky board” trap. Trap consists of 1x0.1 m board covered with a sticky resin and placed flush with tundra sur- face. Certain faunal groups that are scarce or lacking at Barrow are abundant and conspicuous at Prudhoe Bay. In walking across dry tundra, one is quickly struck by the abundance of large wolf spiders (Lycosidae), at least four forms of which are easily recognizable. At Barrow there is but one uncommon wolf spider (7arentula mutabilis), and the true bugs (Homoptera) are represented by a single, uncommon leafhopper (Cicadellidae) species (Hardya young/). At Prud- hoe Bay leafhoppers are very abundant on drier habitats, occurring in lower numbers elsewhere (Fig. 7). In addition, at least one species of leaf bug (Miridae) was found. 2. Abundance of soil fauna. Larvae of vari- ous cranefly species (Diptera: Tipulidae) are an abundant component of many tundra eco- systems. At Barrow larvae of Pedicia hannai Table 1 Comparison of species diversity of some insect families at Barrow and Prudhoe Bay. Barrow list after Hurd (1957) with additions. Prudhoe Bay specimens determined as indicated. Barrow Prudhoe Bay Diptera: Tipulidae Tipula begrothiana Alex. Tipula arctica Curtis Tipula pribilofensis Alex. Tipula diflava Alex Tipula besselsi OstenSacken Tipula macleani (sp. nov.) Alex. Prionocera parii OstenSacken Prionocera gracilistyla Alex. Nephrotoma /undbecki (Nielsen) Pedicia hannai antennata Alex. Pedicia hannai antennata Alex Erioptera kluane Alex Erioptera forcipata Lundstrom Limnophila sp. nov. (Det. by R. Gorham) Tipula carinifrons Holm. Tipula aleutica Alex (Det. by C. P. Alexander) Prionocera gracilistyla Alex. Diptera: Culicidae Aedes cataphylla Aedes impiger Aedes nigripes Aedes nigripes Diptera: Dolichopodidae (Det. by F. Harmston) Dolichopus amnicola Dolichopus consanguineus Dolichopus obcordatus Dolichopus eudactylus Dolichopus ramifer Dolichopus plumipes Dolichopus occidentalis Dolichopus aldrichii Dolichopus humilis Campsicnemus nigripes Hydrophorus gratiosus Hydrophorus sodalis Hydrophorus signiterus Hydrophorus fumipennis Gymnopternus californicus Aphrosylus nigripennis Aphrosylus fumipennis Aphrosylus praedator Raphium tripartitum Raphium sp. (Det. by K. W. Philip) Hydrophorus fumipennis Lepidoptera: Pieridae Colias palaeno Colias hecla Colias thula Colias nastes Lepidoptera: Papilionidae Papilio machaon (Det. by K. W. Philip) Lepidoptera: Lycaenidae (Det. by K. W. Philip) Lycaeides argyrognomon Agriades aquilo Lepidoptera: Nymphalidae (Det. by K. W. Philip) (Det. by K. W. Philip) Boloria frigga Boloria polaris Boloria chariclea Boloria napaea (Det. by K. W. Philip) Oenis melissa Erebia rossii Erebia fasciata Boloria frigga Boloria polaris Boloria chariclea Lepidoptera: Satyridae (Det. by G. C. Byers and C. P. Alexander) Walz reaches densities of 250 m? in wetter habitats, while Tipula carinifrons \arvae may number 100 m2 in more mesic habitats. Their biomass at such densities may exceed 0.5 g dry weight in each case. The density of cranefly larvae was far lower in all habitats at Prudhoe Bay than in comparable habitats at Barrow (Table 2). The greatest density was achieved in the drained lake basin (plots 4 and 5); there, as in wet meadow habitats at Barrow, Pedicia hannai was the domi- nant species. The low density of cranefly larvae may explain the low breeding populations or absence of such shorebird species as the dunlin (Calidris alpina) and pectoral sandpiper (C. melanotos) (Norton et al., this volume) which prey heavily upon cranefly larvae at Barrow. Table 2 Abundance of cranefly larvae (Diptera: Tipulidae) in Prudhoe Bay tundra in 1971 and 1972. Plot 1971 1972 Major forms 1 9.8 m2 i) Tipula 2 2.0 10.0m* — Prionocera 3 3.9 5.0 Tipula, Pedicia 4 17.6 40.2 Pedicia 5 27.4 39.1 Pedicia 6 22.3 Pedicia 7 3.4 Tipula MacLean (1973) suggested that the high density of cranefly larvae at Barrow may be part- ly a result of the causal sequence: low temperature — low productivity > pro- longed life cycle > overlapping larval genera- tions. For example, larval development of Pedicia han- nai at Barrow requires 4 or 5 years. If the warmer summer conditions at Prudhoe Bay allow individuals to shorten the life cycle, the result would be lower biomass at any one time in relation to population productivity. Thus, care must be taken in interpreting density and biomass values from different sites; howeve;, even allowing for possible differences in life cycle length, it is clear that productivity of craneflies is less at Prudhoe Bay than at Barrow. 118 On 29 August 1972, a visit was made to Prudhoe Bay to collect samples to determine the abundance of microfauna (mite, Collembola, and enchytraeid worm). These groups consist of very small invertebrates which, because of their great abundance, collectively comprise the most important element of the soil fauna in many ecosystems. A limited sample processing capabil- ity prevented us from sampling all plots. We selected plots which appeared to span the range of moisture and vegetation features available at Prudhoe Bay. The results, shown in Table 3, are contrasted with results of similar sampling on nine study plots at Barrow. Prudhoe Bay plot 1, a dry Dryas integrifolia heath, represents a habitat not found at Barrow; we might expect it to have greater faunal affin- ities with the Dryas fell-field alpine habitat at Eagle Summit in central Alaska. This plot con- tained an exceptionally high number of prostig- matid mites, but low numbers (in contrast to Barrow) of mesostigmatic and cryptostigmatid mites, and low numbers of the two major super- families of Collembola—the Entomobryidae and Poduridae—and of enchytraeid worms. At Bar- row mites tend to increase in abundance in passing from wetter to drier plots, while Collem- bola and Enchytraeidae decline in abundance along such a moisture gradient. Thus, in general, the Prudhoe Bay plot 1 pattern was predictable on the basis of patterns seen at Barrow. Prudhoe Bay plot 6 is the wettest plot sampled for all three major microfaunal groups. It has a very low abundance of both mites and Collembola, which seems to reflect the ‘‘poly- gon basin syndrome.’’ There are other resem- blances: Carex aquatilis is the only vascular plant species; there is very little, if any, moss or lichen cover; the top 10 or more cm consist of saturated sod with very high organic matter accumulation. The habitat represented by plot 6 differs from the typical Barrow polygon basins in its greater spatial extent and more robust but widely spaced shoots of Carex aquatilis. At Barrow the low invertebrate productivity in polygon basins is symptomatic of (and perhaps causally related to) a general reduction in the rate of ecosystem function relative to other tundra habitats. Primary productivity, microbial activity, and nearly all parameters that have been measured reach minimum values in such habitats. The existence of analogous, and per- haps homologous, habitats occupying greater area at Prudhoe Bay suggests that we may be addressing a general limiting feature of tundra ecosystem function. Prudhoe Bay plot 7, a Dryas-graminiform mesic mixed heath, is closer to the Barrow dry meadows in gross appearance and in microfaunal composition. Prostigmatid mites are abundant; entomobryid Collembola and Enchytraeidae are rather low in abundance. It contained a surpris- ing number of podurid Collembola—more than were found in eight of the nine Barrow plots. In nearly all ecosystems that have been studied, the cryptostigmatid mites, especially Table 3 Abundance of major invertebrate groups (number m°2) at Barrow (seasonal mean) and Prudhoe Bay. Samples taken 29 August 1972. Barrow Group Maximum Minimum Acarina Prostigmata 42,500 4,350 Mesostigmata 7,080 603 Cryptostigmata 38,900 1,600 Total Acarina Collembola Entomobryidae 172,000 22,400 Poduridae 33,200 1,150 Sminthuridae 2,850 0 Total Collembola Enchytraeidae 95,300 11,600 Prudhoe Bay Mean Plot 1 Plot 6 Plot 7 Plots 4/5 18,000 63,200 1,090 38,700 3,260 1,090 109 3,710 20,000 11,900 5,790 4,040 41,300 76,200 7,000 46,500 83,000 11,900 2,180 31,100 8,110 3,820 436 21,400 1,170 3,490 0 7,750 92,300 19,200 2,620 60,300 46,900 15,900 30,900 20,900 32,900 the Oribatei, are by far the predominant group of Acarina. At Barrow, however, Douce (1973) reports that the prostigmatid mites comprised 55% of the individuals and 16 of the 37 species found. Prudhoe Bay is even more extreme in the predominance of prostigmata; 79% of the mites on plots 1, 6, and 7 belonged to this group. This may be a general feature of tundra ecosystems: examination of data produced from other sites of the international Tundra Biome should allow resolution of this point. The total number of Collembola on all Prud- hoe Bay plots was lower than the Barrow mean. Thus, this system is not Collembola-dominated, as is the Barrow system. Differences in faunal composition occur within the Collembola. At Barrow the Entomobryidae comprise 90% of the total individuals; at Prudhoe Bay they comprise 55% of the total. Sminthurid Collembola are rather uncom- mon at Barrow and somewhat more abundant at Prudhoe Bay, although they still do not form a numerically important part of the microfauna. Interestingly, they reach greatest abundance on wet plots at Barrow, but on the two dry plots at Prudhoe Bay. They are missing altogether from the polygon basin plot at Barrow, as they are from Prudhoe Bay plot 2. All of this suggests that there may be areas of wet tundra at Prud- hoe Bay not suffering from the “‘polygon basin syndrome,” in which sminthurid Collembola may reach even greater abundance. Biomass was not measured directly at Prud- hoe Bay. The numeric estimates of Table 3 were converted to biomass estimates using the mean dry weights per individual of 4 ug for Collem- bola, 5ug for Acarina, and 20 wg for Enchy- traeidae. The results are presented in Table 4. As at Barrow, the Enchytraeidae strongly dominate in all habitats sampled. Each of the Prudhoe Bay plots is well below the Barrow mean of 1,514 mg dry wt m2; however, Prudhoe Bay plot 6 corre- sponds precisely with the Barrow polygon basin which it otherwise resembles, and Prudhoe Bay plot 7, the Dryas-graminiform mesic heath, corre- sponds precisely with the Barrow raised polygon. Thus, when comparing similar habitats, the bio- mass of soil microivertebrates at Barrow and Prudhoe Bay is similar. However, the habitats sampled in this study represent a significant pro- portion of the Prudhoe Bay tundra, whereas com- 119 Table 4 Estimated biomass of major invertebrate groups (mg dry wt m°2) at Prudhoe Bay, 29 August 1972. Plots Group Plofl) “Plot6) Plot 7 4/5 Acarina Prostigmata 316 5 194 Mesostigmata 5 O05 7219 Cryptostigmata 60 29 20 Total Acarina 381 35 233 Collembola Entomobryidae 48 9 124 Poduridae 15 2. 86 Sminthuridae 14 0 31 Total Collembola 77 11 241 Enchytraeidae 636 1236 836 1316 TOTAL 1094 1282 1310 parable habitats at Barrow are limited in spatial extent. In other words, habitats low in inverte- brate biomass are the rule at Prudhoe Bay, but the exception at Barrow. As a whole, Prudhoe Bay tundra supports a lower biomass of soil inverte- brates than does Barrow tundra, in spite of the more temperate summer season climate and greater faunal and floral diversity found at Prud- hoe Bay. The depth distribution of microfauna (Table 5) closely paralleled results found at Barrow. The majority of the fauna occurs close to the surface, which is most evident in the mites. All Table 5 Depth distribution of soil microfauna (percent of total occurring in upper 2.5 cm of litter and soil). Plots Group Plot1 Plot6 Plot 7 4/5 Acarina Prostigmata 93 30 93 Mesostigmata 100 0 74 Cryptostigmata 100 100 100 Collembola Entomobryidae 83 100 87 Poduridae 80 50 57 Sminthuridae 100 82 Enchytraeidae 87 87 61 82 120 specimens of cryptostigmatid mites occurred in the top 2.5 cm of the litter and soil. Unlike the north temperate regions, in the arctic soil ani- mals cannot descend to escape the winter freeze. By remaining near the surface, they experience an earlier onset of activity in spring and warmer temperatures during the summer season. 3. Phenology. One of the striking features of tundra ecology is the synchronous emergence of adult insects (MacLean and Pitelka 1971; MacLean, in press). The peak of emergence at Barrow, particularly of the conspicuous Diptera, usually falls in the second week of July approxi- mately one month after melt-off. We were inter- ested in comparing emergence patterns at Prud- hoe Bay where snow melt-off is generally earlier and summer temperatures warmer. Cumulative Captures 50 (% of Total) Date Fig. 1. Derivation of the figure used to describe seasonal pattern of insect activity. Central line represents date of median capture; bar encloses central 80% of captures; total length of horizon- tal line indicates total period of capture. An open-ended line (see Fig. 3) indicates that the first (or last) capture occurred in the first (last) period sampled; a closed line, as shown here, indicates that at least one sample period with no captures preceded (or followed) the first (last) capture. The 2 years of observation at Prudhoe Bay yielded very different results. In 1971 melt-off was nearly complete when observations began in early June. The average of the daily mean air temperatures recorded at the BP-Mukluk based camp during the first week of June was 6.1°C. In 1972 melt-off was delayed by at least 10 days and occurred at approximately the same time as melt-off at Barrow. The average daily mean temperature for the first week of June 1972 was 0.5°C. Thus, invertebrate activity began much earlier in 1971. Air temperatures in the two seasons were then roughly comparable until late July, when 1971 was warmer than 1972. August 1972 was much warmer than August 1971, reversing the earlier trend; thus, temperature differences averaged out for the season. All taxa examined showed a significant delay in emergence in 1972 relative to 1971 (Figs. 2-7). This delay approximately equals the differ- ence in melt-off in the 2 years. This again demonstrates the unimportance of photo-related cues as a timing mechanism for arctic tundra invertebrates. Rather, it appears that emergence follows the completion of a certain amount of metabolic activity which begins at or soon after melt-off. No consistent between-habitat differences are evident in the timing of emergence. In most cases, the dates of median capture of any taxon on all plots fell within a 5-day period. The synchrony of emergence is particularly evident in the Tipulidae, where 80% of the captures occurred within 10-day periods in both years (Fig. 2). Craneflies are important prey for breed- ing sandpipers, and the timing of sandpiper breeding activities has probably evolved so that the hatching of sandpiper young coincides with the appearance of their major prey. The synchronous nature of the emergence allows little room for error. The period of cranefly Diptera: Tipulidae Plot N 4 97 rot} 74 972 i$ 236 97) f=} 64 5 972 a 216 os 1971 = =— 162 972 + — { 626 l =) een | ee Is ea ll i] Fig. 2. Seasonal distribution of “sticky-board” captures of adult craneflies (Diptera: Tipulidae) in 1971 and 1972. emergence, and thus the optimum period for sandpiper breeding, differed by 10 days between 1971 and 1972. Norton et al. (this volume) showed that avian breeding was delayed some- what in 1972, thus preventing severe dis- synchrony between predator and prey; however, it is possible that large, year-to-year differences in sandpiper breeding success relate to differ- ences in the timing of cranefly and other insect emergence. The short summer season that char- acterizes arctic tundra makes timing or phenol- ogical relationships especially important; this may be one area in which the tundra is particu- larly sensitive to small disruptions. The total number of captures in any plot provides an index of abundance that can be used for between-plot and between-year comparisons. The delayed melt-off and prolonged flooding of the lake basin (plots 4 and 5) in 1972 produced no major decline in insect abundance. In fact, Tipulidae and Dolichopodidae (Fig. 3) increased in abundance from 1971 to 1972. Only the parasitic Hymenoptera (Fig. 6) declined from 1971 to 1972, and this occurred on all plots. Captures of leafhoppers (Cicadellidae) were concentrated on the drier plots (Fig. 7). On Diptera: Dolichopodidae Plot N 97 ey 170 972 |__—_—_sees —$—$—{ 544 (0 — SSS 630 a 972 $$ 799 97 aS SS 274 = 972 {$s $$ 272 Tx f —| 42\ 4 972 $e $$$ 6 | 2 5 971 —t + +— 375 972 eer 6 1972 TS 7 1972 EER (as eS | ! ! cee 10 20 30 10 20 30 10 20 29 June July August Fig. 3. Seasonal distribution of “sticky-board” captures of long-legged flies (Diptera: Dolichopodidae) in 1971 and 1972. WA Diptera: Small Nematocera Plot N 1971 SS 2547 1972 |—__ $n SA et t }——————————-__ 4565 2 1972 oe 1978—§ +4 2578 3 1972 _—___/ 1971 ——4 { ee 3 1972 —_——_ $9455 el = t OOS > 1972 —_—— pe 7763 6 1972 | $$. 478| 7 1972 |_— n —_— 4533 — a a Ee ee) @ 2 30. [oO 2 sO" IO eo 2S June July August Fig. 4. Seasonal distribution of “sticky-board” captures of other species of Diptera, suborder Nematocera in 1971 and 1972. Diptera: Brachycera & Cyclorrhapha Plot N ed 0 — 221 1972 | $n 3 1978—§ YX 2 520 1972 —_—__—_—_—_—_ a 387 3 1972 a 198 i — eS 4 716 1972 | Un 5 1971 ——+t t ———————} 704 1972 a 421 6 1972 I 7 1972 _ ore aa a i 1 1 asi 1 J [O} ee cOMNESOM IONS 2On 50 10 20 29 June July Auaust Fig. 5. Seasonal distribution of "'sticky-board" captures of "higher"’ flies (suborders Diptera, Brachycera and Cyclorrhapha) in 1971 and 1972. W222 Hymenoptera: Apocrita Je N 197 == — 96 S72 34 a —— t= «Es : 1972 +4 2.6 2 97 SS! t ———) 108 S 972 28 97 -— { = 742 4 972 —— ee 22 oS — ee 725 ) 972 re 6 1972 |—_—__—_— 6 | im Wr $97 10 20 30 10 20 30 10 20) 29 June July August ut Fig. 6. Seasonal distribution of “sticky-board captures of ‘’narrow-wai/sted’’ parasitic Hymenoptera (suborder Apocrita) in 1971 and 1972. these plots they declined in abundance from 1971 to 1972. Leafhoppers have gradual (in- direct, or hemimetabolic) development. Cap- tures included adults and immatures (nymphs) at various stages of development; thus, the cap- ture period is long. Year-to-year changes in number of captures may reflect differences in activity related to ambient temperature as much as actual differences in abundance. Taking the insect fauna as a whole, the lake basin plots (4 and 5) seem to be the most productive. Only the leafhoppers show a prefer- ence for the drier plots (1, 3, and 7). Plots 4 and 5 tended to show a greater abundance of adult insects than the other wet plots, 2 and 6. This is strongly the case in the Tipulidae, and less so in other groups. It is interesting to note that Enchytraeidae, the only microfaunal group sampled in plots 4 and 5, were slightly more abundant there than elsewhere, but still well below the Barrow mean (Table 3). We conclude that, as at Barrow, wet plots support more invertebrate biomass than dry plots; however, biomass of the most favorable plots at Prudhoe Homoptera: Cicade//idae Plot N 971 ——+ t a 880 1972 ee 197 ae: 2 972 23 97| — = = a 577 S) 972 | $a 330 97 ooo 76 4 972 a 77 ee fat + —— 68 972 =a 35 6 1972 8 7 1972 rnp l | | ee! | as 10 20 30 10 20 30 10 (40) ZS) June July August ut Fig. 7. Seasonal distribution of “sticky-board captures of leafhoppers (Homoptera: Cicadell/i- dae) in 1971 and 1972. Bay is well below biomass of the most favorable plots at Barrow. General Conclusions In general, results obtained at Prudhoe Bay support Our more intensive observations at Bar- row and reinforce their validity for northern Alaskan coastal tundra as a whole. It is interest- ing to note that the Prudhoe Bay tundra tends to be of lower productivity than Barrow tundra despite the longer and warmer growing season and greater floral and faunal diversity of Prud- hoe Bay. Thus, we must conclude that the low productivity of tundra systems is not a direct and simple result of the severity of the climate. The distribution of individual species (as reflect- ed in diversity), however, may be more directly influenced by climate. The link between eco- system complexity (diversity) and function is clearly a complex one, and we must avoid simplistic statements relating diversity and pro- ductivity, stability, or other integrative eco- system parameters. Acknowledgments The field work was performed with enthusi- asm and diligence by Mark E. Deyrup in 1971 and Craig Hallingsworth in 1972. The micro- invertebrate sampling and identifications were the responsibility of G. Keith Douce (Acarina), Maggie E. Skeel (Collembola), and Edward A. Morgan (Enchytraeidae). This project was primarily supported by the National Science Foundation grant GV-29342 to the University of Alaska, under the auspices of The U.S. Tundra Biome Program. Field logistics were provided through the Prudhoe Bay Envir- onmental Subcommittee’s support through the Tundra Biome Center. References Douce, G. K. (1973). The population dynamics and community analysis of the Acarina of the arctic coastal tundra. M.S. thesis. Univer- sity of Georgia, Athens, 69 pp. 123 Hurd, Jr., P. D. (1957). Analysis of soil inverte- brate samples from Barrow, Alaska. Final Project Report to A.I.N.A., 24 pp. mimeo. MacLean, Jr., S.F. (1973). Life cycle and growth energetics of the arctic crane fly (Pedicia hannai antenatta). Oikos, 24(4):436-443. (1975). Ecological adaptations of tundra invertebrates. Pages 269-300 /n (J. Vernberg, ed.) Proc. E.S.A./A.1.B.S. Symp., Amherst, Mass. June, 1973. Intext Press, New York. MacLean, Jr., S. F. and F. A. Pitelka. (1971). Seasonal patterns of abundance of tundra arthropods near Barrow. Arctic, 24:19-40. Norton, D. W., |. W. Ailes, and J. A. Curatolo (This volume). Ecological relationships of the inland tundra avifauna near Prudhoe Bay, Alaska. Webber, P. J. and D. A. Walker (This volume). Vegetation and landscape analysis at Prud- hoe Bay, Alaska: A vegetation map of the Tundra Biome study area. 124 Data Center, University of Alaska C.D. Evans, Arctic Environmental Information and y % nt we eS ee aS Fee Adult Black-bellied plover (Pluvialis squatarola), a characteristic breeding bird of vegetation type 1 (Webber and Walker, this volume). 125 Ecological Relationships of the Inland Tundra Avifauna near Prudhoe Bay, Alaska DAVID W. NORTON* Institute of Arctic Biology University of Alaska Fairbanks, Alaska 99701 IRVIN W. AILES Department of Wildlife and Fisheries University of Alaska Fairbanks, Alaska 99701 JAMES A. CURATOLO Alaska Cooperative Wildlife Research Unit University of Alaska Fairbanks, Alaska 99701 Introduction Two motivations prompted a quantitative study of terrestrial birds at Prudhoe Bay. The first was a basic comparison of abundance, species composition, diversity, phenology, and productivity at that site with similar observa- tions at Point Barrow, Devon Island, and other northern sites where birds have been studied in relation to their resources. The second purpose was to examine generally the applied problems of tundra birds’ coexistence with recent and projected oil and gas developments in arctic North America. The nearest well-known avifauna is that of Point Barrow, some 320 km WNW of Prudhoe Bay. A series of behavioral, ecological, and energetic studies of various species has been under way since the early 1950s. Information generated by these studies has been enveloped by the U.S. Tundra Biome, resulting in an evalua- tion of the Barrow avifauna in the broad eco- systems context. We now know that the unique species composition and trophic dynamics there are the result of a largely saprovore-based food chain. That is, many of the terrestrial avian consumers depend on soil-dwelling, saprovorous arthropods, principally the dipteran families Tipulidae and Chironomidae (Holmes 1966; MacLean and Pitelka 1971; Norton 1973). Breeding shorebirds dominate the tundra in sum- mer, as they seem especially capable of acquiring soil-dwelling larvae and surface-dwelling adult insects in quantities sufficient to support the high energy requirement of breeding in cold environments. The factors making insectivory a feasible strategy for breeding birds at Barrow appear to be the unusual proportion of primary produc- tion entering the litter category susceptible to consumption by saprovores, the consequent high standing crops of larval saprovores, and the interdigitation of moist and dry tundra on a fine scale (‘‘fine-grained mosaic’’ of MacLean 1969) that permits birds to select from radically dif- ferent feeding habitats within short distances. Prudhoe Bay tundra differs from that of Barrow, lacking the extreme variability of micro- relief and moisture over short distances. Never- theless, we expected an important saprovore- based trophic system favoring a_shorebird- dominated avifauna at Prudhoe Bay. *Current address: Outer Continental Shelf Project, University of Alaska, Fairbanks, Alaska 99701. 126 70° 30 oe . i gs aN U¢ A S EA \ \ ov ari \ ) J () A (7 Pt. Mcintyre sie f, 2D & \ F i «+f i ik @¢« ba A = C ant 6 oy "Ox Pe WF ) Ao € J jake Z 35 ¢ f \7\ R i Oe, @ igo = ¢ = ~ : eae YoY A € = a ic ~ x ets i ee ~ > a & ae a, [c £ ¥ s ra ee < z D) | vl gs te) sa, ey ‘ 0 \ A } QO \ ) € Ce G \ + '¢ Ad i ad ~ rn a = f ° POSE Ne vou eee ad eG) G a a 5 a5 Bed J 4, f 149°00' 148°40' Fig. 1. Avian census plots in the Prudhoe Bay Region, 1971, 1972. 148°20' Actual or potential impacts of exploitation and transportation of arctic oil and gas on biological systems have gained a great deal of attention, but sufficient time and funding for serious, long-term scientific evaluation of these impacts have not been available. Consequences of such activity which may directly and nega- tively affect resident birds include noise disturb- ance; loss, destruction, or alteration of habitat, and spills of toxic materials. But these are obvious effects which could be offset with obvious countermeasures. One can argue that the extirpation of a few breeding species from a limited area may be unimportant. Historically, the less obvious effects of human activities have had far greater consequences for ecological systems. We therefore tried to identify any such systems effects as we encountered them in the course of this 2-year study. We viewed the small species with which we were dealing more as ecological indicators than as valuable resources in themselves. This approach is basically differ- ent from a resource management approach such as that of a waterfowl biologist, whose mandate is to protect and enhance productivity. Methods Visual census coverage of measured tracts, as developed for avifaunal studies at Point Barrow (Norton 1973), was used to evaluate the dynam- ics of bird populations using Prudhoe Bay tun- dra. Two census plots, A and B, each measuring 500x700 m (0.35 km), were erected and mark- ed in 1971. A third plot, C, measuring 200x500 m (0.1 km2), was erected in 1972 and deliberately located away from the lee, or west, side of nearby roads (Fig. 1). Each plot was censused systematically by one to three observers who walked the grid and recorded locations of each bird encountered. The intervals between formal censusing (4-12 days depending on weather, level of activity, and estimated rates of change in populations present) were used in searching for nests, color- banding adult and young birds trapped at their nests, and recording the progress of nests under observation. The proportion of birds, either unbanded or unaccounted for as nesting, theore- tically should drop to near zero if the technique is successful. General observations outside the census 127 Calidris pusilla Tryngites subruticollis 2 ? ? ? °E , | | Calidris alpina Clutches Completed per Day 2 O 2 Calidris melanotos fe) 2 Lobipes /obatus O Calcarius lapponicus A Ualilalilssilapal A Ueda wett cue eee a O 5 10 15 20 25 30 5 0 Successful hisri @ Successful July M Predated ! @ Predated Fig. 2. Breeding phenology measured by clutch completion dates for seven species at Prudhoe Bay, 1971, 1972. plots also were made regularly over the wide area accessible by the road system. This study thus complements that of Gavin (1971), which deals primarily with waterfowl. Gavin lists 54 species observed in 1969 and 1970 over a much wider geographical area. However, his treatment of small terrestrial species was incomplete. Results Table 1 lists the 53 species of birds encoun- tered during the two-season survey and distin- guishes known breeding, suspected breeding, regularly and casually occurring species. Al- though we could certainly have expanded this list through attentive observation, particularly during the spring influx of species, we were preoccupied with the regularly occurring species that accounted for the major share of tundra resource use in this region. Of 34 known or suspected breeding species in Table 1, only seven regularly used primarily terrestrial resources to support breeding within 128 Table 1 Species observed in the Prudhoe Bay region, 1971-72. Gavia adamsii G. arctica pacifica G. stellata Cygnus columbianus Branta canadensis minima Branta nigricans Anser albifrons frontalis Chen caerulescens caerulescens Anas platyrhynchos platyrhynchos Anas acuta Anas americana Anas clypeata Aythya marila nearctica Clangula hyemalis Polysticta stelleri Somateria mollissima v-nigra Somateria spectabilis Somateria fischeri Melanitta perspicillata Mergus serrator serrator Buteo lagopus sanctijohannis Lagopus lagopus alascensis L. mutus nelsoni Grus canadensis canadensis Charadrius semipalmatus Pluvialis dominica dominica P. squatarola Arenaria interpres (subsp) Capella gallinago delicata Micropalama himantopus Limnodromus scolopaceus Calidris alpina sakhalina C. pusilla C. bairdii C. mauri C. melanotos C. alba Tryngites subruficollis Phalaropus fulicarius Lobipes lobatus Stercorarius pomarinus S. parasiticus S. longicaudus Larus hyperboreus barrovianus Xema sabini sabini Sterna paradisea Nyctea scandiaca Asio flammeus flammeus Corvus corax principalis Motacilla flava tschutschensis Acanthis (sp.) Calcarius lapponicus alascensis Plectrophenax nivalis nivalis KB — Known breeding in Prudhoe region SB — Suspected breeding Yellow-billed loon Arctic loon Red-throated loon Whistling swan Canada goose Black brant White-fronted goose Snow goose Mallard Pintail American wigeon Shoveler Greater scaup Oldsquaw Steller’s eider Common eider King eider Spectacled eider Surf scoter Red-breasted merganser Rough-legged hawk Willow ptarmigan Rock ptarmigan Sandhill crane Semipalmated plover American golden plover Black-bellied plover Ruddy turnstone Common snipe Stilt sandpiper Long-billed dowitcher Dunlin Semipalmated sandpiper Baird’s sandpiper Western sandpiper Pectoral sandpiper Sanderling Buff-breasted sandpiper Red phalarope Northern phalarope Pomarine jaeger Parasitic jaeger Long-tailed jaeger Glaucous gull Sabine’s gull Arctic tern Snowy owl Short-eared owl Common raven Yellow wagtail Redpoll Lapland longspur Snow bunting M — Regular movement or migration through region C — Casual movement or migration through region the census plots during this study. Shorebirds dominated this group (six of seven species) even more strikingly than is the case at Barrow (seven of 11 species—Norton 1973). The two seasons, 1971 and 1972, differed in weather: the first was comparatively mild with an early and regu- lar snowmelt, whereas the second was cold with a delayed and prolonged snowmelt. This differ- ence between seasons was reflected in delayed onset of nesting by most or all of the species, as indicated in Fig. 2. Overall nesting success (eggs hatched/eggs laid) was universally higher in 1972 (Table 2). This improvement may be related to a reduction in local arctic fox (Alopex lagopus) populations during the winter of 1971-72 through a deliber- ate trapping program conducted around Prudhoe Bay (W. Hanson, pers. comm.) to remove nul- sance animals attracted to refuse disposal areas. Foxes were observed more frequently on the plots in 1971 and were strongly suspected to be the major (if not sole) agents of nest predation that year. Nesting densities of Prudhoe Bay birds were lower than those of their ecological counterparts at Barrow (Table 3), with the exception of the semipalmated sandpiper (Ca/idris pusilla) and red phalarope (Phalaropus fulicarius). \t is very difficult, however, to circumscribe the appro- priate species as being ecologically equivalent in the two localities. Although the nine species listed in Table 3 are the major insectivores (and granivores) in each region, there are additional insectivorous species in the Barrow system, such as the ruddy turnstone (Arenaria interpres); 129 golden plover (Pluvialis dominica), and non-nest- ing long-tailed jaegers (Stercorarius longicaudus). These three species are omitted from Table 3 because of their absence as significant elements at Prudhoe in 1971 or 1972. Their inclusion in this analysis would demonstrate more clearly the greater use of tundra arthropod resources by birds in the Barrow area. Data in Norton's (1973) bioenergetic studies of Barrow shorebirds may be used to estimate that insectivorous species there ingest some 4x10° kcal km-2 yr-! from the tundra arthropod resources. The same estimation procedure for Prudhoe Bay would probably put energy ingested by comparable members of the community at somewhat less than 75% of the Barrow system, or about 3x10° keal km-2 yr! in 1971 and 1972. Various inter- and intra-plot comparisons of census information may be used to discern the spatial and temporal patterns of resource use by Prudhoe Bay birds. For example, Plots A and B became snow-free early and approximately simultaneously each year, and bird counts dropped to less than 10% of peak abundance by late July on each plot. By contrast, Plot C was slower by 7-10 days to become snow-free in 1972. Its bird populations remained at 20-25% of peak numbers until the end of July. This situation is parallel to that found in different plots at Barrow (Norton 1973, p. 21). Late season resource use seems to be concentrated on areas unavailable earlier in the season. Another way to demonstrate this assertion is to break down census information from Plot B by in- dividual rows within the plot (Figs. 3a, 3b, 4). Table 2 Nesting densities (nests km°2) and hatching success (eggs hatched/eggs laid) by species and year at Prudhoe Bay. Year 1971 Year 1972 Density Success Density Success Species (nests km?) (nests km’2) C. pusilla S7A 0.52 42.4 0.84 P. fulicarius S751 0.31 22:2 0.83 T. subruficollis 2.8 0.0 5.7 1.0 C. alpina 4.3 0.0 5.0 1.0 C. melanotos 5.7 0.33 5.7 1.0 L. lobatus 4.3 0.33 5.7 1.0 C. lapponicus 8.6 0.47 6.7 0.73 Overall 99.9 0.38 93.4 0.86 130 Table 3 Nesting densities and success compared between similar avifaunal components at Prudhoe Bay and Barrow. PRUDHOE BAY Density Species (nests km?) C. alpina 4.6 C. pusilla 39.8 C. bairdii = C. melanotos 5.7 T. subruficollis 4.3 P. fulicarius 29.7 L. lobatus 5.0 C. lapponicus hed P. nivalis Be Overall 96.7 ' Calidris species data based on Norton (1973). 2Phalarope data from 1971 at Barrow only—preliminary. 3_ongspur information from T. W. Custer (pers. comm.). BARROW Success Density Success (nests km) 0.5 13.9 0.72 0.68 9.8 0.73 se 24.8 0.39 0.67 13.6 0.69! 0.50 SS = 0.57 (26.4 0.50] 2 0.67 = = 0.60 [30.0 0.63] 3 = [15.0 0.80] 4 0.62 (133.5 0.65] 4 Snow bunting data from 1971 IBP census plot only—incomplete. Row E represents the interface between terres- trial and aquatic systems that was partially underwater until about 20 June 1971, and until 1 July 1972. By those dates, most nesting birds were in late stages of commitment to territories on the western and central rows of Plot B. As soon as the sizeable lake east of Plot B was partially drained, heavy use of the formerly submerged land began. Shorebirds with broods of young could be found abundantly in Row E and eastward thereafter. In summary, tundra birds appear to move seasonally through a series of habitats that are successively later to emerge from either snow or water. Recaptures of semipalmated sandpipers banded in 1971 have confirmed findings by U. N. Safriel (1971, pers. comm.) on the mating system of this species. Fig. 4 shows the recap- ture histories of the 14 pus///a that returned in 1972. All 14 returning birds nested successfully in 1971, although three of them only did so by renesting following predation of their first 1971 nest. In three cases, both banded members of pairs returned, and the 1972 nests of these six birds were all less than 100m from the 1971 nest. Only one known case of remating occurred between the two seasons. No young of 1971 returned as breeding adults in 1972. The semi- palmated sandpipers at Prudhoe Bay therefore are similar to those breeding at Barrow— monogamous, site-tenacious, and mate-faithful. They are especially faithful to mates and terri- tory following reproductive success in the previ- ous season. Young birds do not breed until at least their second year. No Lapland longspurs (Ca/carius lapponicus) or snow buntings (P/ectrophenax nivalis) banded in 1971 returned to Prudhoe Bay plots in 1972, but this may be explained by the small sample size. Banding of male red phalaropes and female pectoral sandpipers (Ca/idris me/anotos) in 1971 and an absence of returning birds in 1972 indicates that these species at Prudhoe, as at Barrow, display no site-tenacity. Discussion Tundra resource use by terrestrial birds at Prudhoe Bay is essentially similar in pattern to that of Barrow birds despite difference in species composition, density, and reproductive success. Information from this study places Prudhoe Bay on a continuum of sorts, relating to terrestrial June July Aug a. Numbers of birds counted (all species) by date and row of census plot. = b. = 2 Lake Shore: > Before 20 June © | After 20 June Lu @ O ns o A B ce D E Row b. Schematic cross section of Plot B, showing approximate ele- vation above lowest point on the east margin of the plot. Fig. 3. Spatial and temporal patterns of avian abundance, Plot B, Prudhoe Bay, 1977. productivity and species diversity of sites at different latitudes and dominated by various physical factors. At one end of this continuum are the preliminary results of Pattie (1972) from Devon Island in the Canadian arctic. The other end of the continuum would presumably lie in tropical rain forests. Table 4 summarizes popula- tion estimates and such energy flux estimates as exist from nine northern community types for approximately ecologically equivalent compo- nents of the avifauna (insectivores and grani- vores), as discussed in this study. Farther south, species diversity, the relative importance of pas- serines, total avian biomass, and energy flux through avian populations may be expected to increase. Holmes and Sturges (1973), for example, estimated that a minimum of 5x10® kcal km? yr! was ingested by temperate forest birds at Hubbard Brook, N. H. The pieces of this global picture will probably continue to come into sharper focus with the present emphasis on measuring productivity at many sites. 131 => See 15 June l971 = Lal { 1 oreline nie sonic Recaptured, re-nesting off plot in 1972 @ 197! Nest <> @i972Nest @ —>@ Re-nest @—-B Return ~ Deep Water 42 Shallow w/Emergent Vegetation Fig. 4. Schematic recapture histories of Semi- palmated sandpipers from 1977 nests on Plot B, showing site-tenacity and mate-faithfu/ness. All breeding birds at Devon Island, Barrow, and Prudhoe Bay are subjected periodically to widespread reproductive failure because of predation and probably physical factors. In the case of nest predation at Prudhoe Bay in 1971, it is likely that human activities were at the base of a chain of events leading from garbage dis- posal through attraction of foxes and abnormal- ly heavy predation pressure by them to avian reproductive failure. Garbage disposal is a criti- cal problem for industrial development in Alas- ka, as elsewhere. Improper disposal, leading to unnatural attraction of potentially nuisance or noxious species, is a quick, sure, and subtle modifier of ecosystem function, especially where the volume of garbage is great. Another form of human impact on systems function has arisen from ground transportation developments in the Prudhoe Bay region. Raised roadbeds alter the accumulation of wind-driven snow and may significantly impound water dur- ing spring runoff. Downwind fallout of dust and 132 Table 4 Partial compilation of species diversity, population densities, and energy flux through northern avian communities. No. Lat Total Site (2) Habitat spp. Devon Island (Canada) 76 tundra = Barrow (USA) 71 tundra 9 Prudhoe Bay (USA) 70 tundra 7 Cape Thompson (USA) 68 tundra 5 Fairbanks A (USA) 65 taiga 22 Fairbanks B (USA) 65 bog-taiga 10 Great Slave Lake (Canada) 62 taiga 12-15 Vaksvik | (Norway) 62 subalpine [18] * Vaksvik Il (Norway) 62 subalpine [12] * [ ]* passerines only. gravel from winter traffic changes the reflec- tance of the snow cover, leading to altered rates of melting and sublimation of snow in the spring. We have not been able to quantify such effects, nor to identify alarming results on local avian ecology per se. The clear movements of individual birds from early- to late-emerging habitats (Fig. 4), however, suggest that spatio- temporal patterns of abundance and resource use will be altered by such structures on the arctic coastal plain. Furthermore, these may be only the first, few, short-term results of many subtle and longer-term changes in local biotic systems. Acknowledgments This study was largely supported by the National Science Foundation grant to the Uni- versity of Alaska under the Tundra Biome Pro- gram. Field logistics were provided through the Prudhoe Bay Environmental Subcommittee’s support through the Tundra Biome Center. References Carbyn, L.N. (1971). Densities and biomass relationships of birds nesting in boreal forest habitats. Arctic, 24:54-61. Gavin, A. (1971). Ecological survey of Alaska’s north slope, summer 1969 and 1970. Un- publ. brochure, Atlantic Richfield Co. T3ipp: Proportion Pr. or Ingested passerines nests km°2 Ekm Source 0.33 2(?) 6x10* kcal Pattie (1972) 0.22 134 4x10° kcal Norton (1973) 0.14 97 3x10° kcal This study 0.20 160 — Williamson et al. (1966: Table 10) 0.91 133 5x10® kcal West & DeWolfe (1974) 1.0 53 1.8x10® kcal West & DeWolfe (1974) 0.74 180-428 - Carbyn (1971) ? 380 — Ytreberg (1972) 2 91 - Ytreberg (1972) Holmes, R. T. (1966). Feeding ecology of the red-backed sandpiper (Ca/idris alpina) in arctic Alaska. Ecology, 47:32-45. Holmes, R. T. and F. W. Sturges. (1973). Annual energy expenditure by the avifauna of a northern hardwoods ecosystem. O/kos, 24:23-28. MacLean, S.F., Jr. (1969). Ecological deter- minants of species diversity of Arctic sand- pipers near Barrow, Alaska. Ph.D. disserta- tion, University of California, Berkeley, 194 Pp. MacLean, S.F., Jr. and F. A. Pitelka. (1971). Seasonal patterns of abundance of tundra arthropods near Barrow, Alaska. Arctic, 24: 19-40. Norton, D. W. (1973). Ecological energetics of calidridine sandpipers breeding in northern Alaska. Ph.D. dissertation. University of Alaska, Fairbanks, 163 pp. Pattie, D. L. (1972). Preliminary bioenergetic and population level studies in high arctic birds. Pages 281-292 jn Devon Island |.B.P. project, high Arctic ecosystem (L. C. Bliss, ed.). Safriel, U.N. (1971). Population study of the semipalmated sandpiper, Ca/idris pusilla. Page 35 in 1971 AAAS Mtgs. Proc. 22nd Alaska Sci. Conf. 133 437-480 jin Environment of the Cape Thompson region, Alaska, Wilimovsky and Webber, P. J. and D. A. Walker (This volume). Wolf, eds.) U.S. A.E.C., Oak Ridge, Tenn. Vegetation and landscape analysis at Prud- hoe Bay, Alaska: A vegetation map of the Tundra Biome study area. ; , Wes GG BOUT EL CID tone ernie AUC send Rabe ETS SiMe in ica é : ; ; : bird populations in the breeding season, tions and energetics of taiga birds near Fair- : : ; 1968-1970, on two mountain forest habitats banks, Alaska. Auk, 91:757-775. on the west coast of southern Norway. Williamson, F.S. L., M.C. Thomson, and J. QO. Norw. J. Zool., 20:61-89. Hinds (1966). Avifaunal investigations. Pages 134 <> Ne 5 F : ; bc ae Brown lemming |Lemmus Sibericus (=trimucro- aw natus)] at edge of snow patch. Dr. John Koranda, Lawrence Radiation Laboratory 135 Population Studies of Lemmings in the Coastal Tundra of Prudhoe Bay, Alaska DALE D. FEIST Institute of Arctic Biology University of Alaska Fairbanks, Alaska 99701 Introduction Previous studies of microtine rodents on the arctic coastal tundra at Barrow have demonstrat- ed marked fluctuations of lemming populations and considerable impact of high numbers of lemmings on local habitat (Pitelka 1957, 1973). However, the importance of microtine rodents in the total flow of energy and nutrients in the tundra ecosystem remains to be evaluated (Batzli, in press). Furthermore, it is not clear whether we can generalize from the limited studies at Barrow as to the species and numbers of microtine rodents and their importance in the tundra ecosystem at other sites along the arctic coast of Alaska. The present studies of lemming populations were initiated on the arctic coastal tundra near Prudhoe Bay in the summer of 1971 to provide comparative data in conjunction with other investigations of the tundra ecosystem conduct- ed by the U. S. IBP Tundra Biome Program. The initial objectives were to assess: (1) the produc- tivity of microtine rodent populations; and (2) the effect of microtine rodent populations on the net primary production. The Prudhoe Bay area was of interest both for basic studies of coastal tundra and for the potential impact of local human activities (exploration and extrac- tion of oil) on the tundra ecosystem. Materials and Methods Study area The general area of arctic coastal plain near Prudhoe Bay selected for studies by the U.S. IBP Tundra Biome Program lies at about 75° 15’N latitude and is bounded on the west by the Kuparuk River and on the east by the Sagavanirktok River (Fig. 1). Much of the land surface consists of ponds and shallow lakes. The terrestrial habitat has limited relief and is domi- nated by drained lake basins with varying degrees of polygonization. The summer climate is notably warmer than that of Barrow; rapid snowmelt generally occurs in early June, and mean summer air temperatures are +2.6, +6.4, and +4.8°C in June, July, and August, respec- tively (Brown et al., this volume). The vegeta- tion is typical of the arctic coastal plain and has been described in detail by several investigators (Neiland and Hok, this volume; Webber and Walker, this volume). During the summer the area serves as a breeding ground or temporary stopping place for as many as 53 different avian species, mostly shore birds and waterfowl! (Norton et al., this volume). Several species of jaegers (Stercorarius sp.), the snowy owl (Nyctea scandiaca), and the short-eared owl (Asio flammeus) may act as predators on microtine rodents. 136 f Small Mammal S Live Trap Grids fe) rse « epAirfield As ) RS 149°00' 148°40' 148°20' Fig. 1. Small mammal trapping sites within the Prudhoe Bay area designated for U. S. IBP Tundra Biome studies. In addition to microtine rodents, arctic ground squirrels (Cite//us undulatus) reside in the area. Arctic fox (A/opex lagopus) roam as predators of these small mammals (Underwood, this volume). Populations of caribou (Rangifer tarandus granti) graze the area during the sum- mer (White et al., this volume). About a dozen other species of mammals, including the grizzly bear (Ursus horribilis) and wolf (Canis lupus), have been occasionally reported in the general vicinity of Prudhoe Bay (Bee and Hall 1956). Live trapping: Capture-mark-recapture To assess numbers and demographic features of the microtine rodent populations, live trap- ping grids for small mammals were established in early June 1971 at locations shown in Fig. 1. The primary study areas were near the intensive IBP sites on the west side of the road leading NE to the Putuligayuk River. Live trap grid P was set at about 70°16’N, 148°34’W in a habitat with low relief polygons and tussocks. Live trap grid O was set about 1 km SW of grid P in a flatter habitat of low relief tussocks. In June 1972 a third live trap grid S was established across the road (1 km NE of grid P) on a low pingo and the surrounding, very low relief tussocks. The live trapping, mark, and recapture ap- proach was similar at all locations. Live trapping grids consisted of 100 trap stations (10 rows x10 rows) at 5 to 6 m intervals (total area = 0.25 ha). One large, Sherman live trap and a nest can with cotton bedding and oats was placed at each station. During each trapping period of 2 to 5 days, traps were checked in the morning and afternoon. In some instances traps were checked more frequently (as often as every 4 hours) to reduce or eliminate trap mortality. Traps were locked open during the interval of 2 or 4 weeks between trapping periods. At first capture in each period, animals were tagged on the right ear with a fingerling tag, weighed with a Pesola spring scale, and examined for reproductive status before release at the site of capture. Females with a perforate vagina or vaginal plug, open pubic symphysis, and/or enlarged teats (nipple more than 1 mm in diameter) were considered in breeding conditions, as were males with scrotal testes (Krebs 1964; Batzli and Pitelka 1971). Trapping usually was continued 137 in a period until all tagged animals were re- captured. Temporary live and snap trapping In addition to maintaining these permanent live trap grids, attempts were made to capture microtine rodents at other locations by tempo- rary snap trapping and live trapping. In June 1971, snap trapping grids were set out at two sites: (1) on the area later established as live trap grid S; and (2) across the main road from the intensive sites to the SW of the live trap grids. These snap trap grids consisted of 100 stations (10 rows x 10 rows) at 10 m intervals with two Victor-type snap mousetraps per station. The closed traps were prebaited with peanut butter 3 days prior to trapping. They were checked at least twice per day for 5 days during the trap- ping period. These same two sites were trapped again in August 1971, but with temporary live traplines consisting of two parallel rows of 25 stations at 5 m intervals and one large Sherman live trap per station. Rows were about 25 m apart, and traps were checked twice per day for 5 days. In July 1971 two new areas about 10 km NW of the Putuligayuk River, just NE of Frontier Camp and just N of Western Pad, were explored and trapped with the same type of temporary live traplines. In August 1972 at- tempts were made to capture lemmings near pad F with temporary live traps. Estimates of density Estimates of density were calculated from the number of animals captured during a trap- ping period and the effective trapping area. The effective trapping area was calculated for each “sex-age’’ group of lemmings by adding a bound- ary strip around the actual 0.25 ha grid area. The size of the boundary strip was based on previous studies of collared lemming (Dicro- stonyx groenlandicus) movements and range by Brooks and Banks (1971). It was assumed, but remains to be confirmed, that the range lengths found for different sexes and ages of collared lemming at Churchill, Man., Canada (Brooks and Banks 1971) apply to the lemmings at Prudhoe Bay as well. Thus, for each ‘‘sex-age’’ group a boundary strip of approximately half the aver- age range length was added to the original grid size to give the effective trapping areas shown under Table 3. 138 Table 1 Numbers” of collared lemmings on three grid areas near Prudhoe Bay during the summers of 1971 and 1972. mid-June early July late July mid-Aug. June July Aug. (19-23) (5-9) (24-31) (21-25) 1971 1971 1971 1972 1972 1972 1972 Numbers Grid P Male: << 25q°* 25-50g > 50g Female: < 25g 26-50g > 50g TOTAL (New) Grid O Male: < 25g 25-50g > 50g Female: < 25g 25-50g > 50g TOTAL (New) Grid S Male: < 25g 25-50g > 50g Female: < 25g 25-50g > 50g TOTAL (New) *Numbers given represent estimated minimum numbers present 0.25 ha! grid area at each time, based on numbers captured. **Each sex has been grouped into three weight classes which are assumed to approximate the age classes of juvenile (< 25g), subadult (25-50g), and adult ( >50g). p = pregnant. +In late August two arctic ground squirrels (Cite//us undulatus) were captured in grid P. Analyses of predator scats and pellets To help determine what species of microtine rodents inhabit the Prudhoe Bay area, owl pel- lets, jaeger pellets, and fox scats were collected during the summer of 1971. About 80% of the 224 fox scats came from outside a den about 200 m NW of live trap grid O. The remainder of scats and the 11 pellets were from other loca tions away from the live trap grids. The scats and pellets were teased apart, and the skeletal remains of prey were identified by species when possible (Bee and Hall 1956; Burt and Grossen- heider 1964). Results Numbers, biomass, density As shown in Table 1, only two lemmings were captured during the entire summer of 1971. During the first trapping period in June, two collared lemmings were captured, marked, and recaptured on grid Q. Although fresh fecal droppings were found around and in some of the traps in June and July, no other lemmings or other microtines weré captured during the re- mainder of the summer on either grid. In late August, two arctic ground squirrels were cap- tured on grid P. No animals were captured on any of the temporary live trapping or snap trapping sites during the summer of 1971. In June 1972 an increased activity of micro- tine rodents over the previous summer was apparent from the fresh signs of burrows and fecal pellets. Observations over a wide area of Prudhoe Bay road system suggested a low to moderate level of activity and a very patchy distribution. Live trapping revealed a definite increase in numbers of collared lemmings in June 1972 [5-8(0.25 ha)! grid area] over the level in June 1971 [0-2(0.25 ha)! grid area] (Table 1). The presence of three juveniles of 12-14g on grid P indicated that breeding had begun before the snowmelt. Although subadults and adults of both sexes remained in breeding condition with adult females pregnant through late July, the numbers captured declined from 5-7(0.25 ha)! grid area in early July (Table 1) to 0-1(0.25 ha)! grid area by late August. Biomass of live lemmings captured on each grid is shown in Table 2 and simply follows the trend in numbers captured through the summer of 1972. 139 Density estimates of collared lemmings based on the number captured and the assumed range of movements (Brooks and Banks 1971) are shown in Table 3. Densities were generally higher on grids P and O and reached maximums of 10.2 and 6.6 lemmings ha’! respectively, in July. Lemming species in predator scats and pellets Although there were many pieces of uniden- tifiable microtine remains in the predator scats and pellets (about 50%), of the total 16% were identified as collared lemming, 13% as brown lemming [Lemmus sibericus (=trimucronatus)] and 25% unidentified bird remains. M/crotus oeconomus (tundra vole) could not be positively identified in these samples, although it had been previously found by MacLean (pers. comm.) in raptor pellets. Discussion Species composition and numbers The results suggest that at Prudhoe Bay, in contrast to Barrow, the collared lemming may be more abundant than the brown lemming and that the lemming populations at Prudhoe Bay may never reach the magnitude seen at Barrow. Examination of the tundra for fresh signs of microtine rodent activity by S. MacLean in July 1970 (pers. comm.) and P. Whitney (pers. comm.) in September 1970, revealed little evi- dence of small mammal activity. In early Sep- tember 1970, Whitney (pers. comm.) established two live trapping grids near the sites of grids P and QO in the present study, but captured no microtines during 2 days of trapping. Thus, it appears that the lemming populations were quite low in 1970, remained low in 1971, and reached trappable numbers as high as 8 collared lem- mings (0.25 ha)' grid area, or a maximum density of about 7-10 lemmings ha’! during the summer of 1972. One or two isolated instances of hand cap- turing of brown lemmings were reported in bird censusing areas in 1971 (I. Ailes, pers. comm.) and 1972 (J. Curatolo, pers. comm.). In addi- tion, brown lemmings were identified as a prey item in the diet of the arctic fox in 1971-72. However, the amount of lemming prey sign was considered sparse at Prudhoe Bay fox den sites compared to sign at den sites in other areas of the Alaskan North Slope (Underwood 1974). In spite of evidence for the presence of brown 140 Table 2 Biomass” (grams) of collared lemmings on three grid areas near Prudhoe Bay during the summers of 1971 and 1972. June July Aug. mid-June early July late July mid-Aug Grid P 1971 1971 1971 1972 1972 1972 1972 Biomass: ~ Male 194(5) 155(5) 32(1) Female 84(3) 95(2) 70(1) TOTAL 0 0 0 278 250 102 0 Grid O Biomass: Male 31(1) 62(2) 108(3) 60(3) Female 36(1) 103(3) 100(3) 48(1) TOTAL 67 0 0 165 208 108 0 Grid S Biomass: Male 0 15 32(1) Female 80(1) 62(1) 0 TOTAL 0 0 Q 80 0 77 32 *Live weight biomass of lemmings captured on the 0.25 ha grid area. +Numbers in parentheses are the number of lemmings for each biomass value. lemmings, this species was never seen or cap- tured in the present study. Maximal densities reported for lemmings in tundra habitats at Barrow have been 1-30 ha’! for Dicrostonyx groenlandicus (Batzli, in press) and 75-200 ha! for Lemmus sibericus (Schultz 1969; Maher 1970). In contrast to the predomi- nance of Dicrostonyx found at Prudhoe Bay in 1971-72, the numbers of Lemmus generally have exceeded those of Dicrostonyx at Barrow and the brown lemming is considered the only grazer of significance in the grass-sedge tundra of the Barrow region (Pitelka 1973). Pitelka (1973) has suggested that the higher densities of Djicro- stonyx may be reached only occasionally (every 20 years) at some locations. Maximal densities of Dicrostonyx estimated at tundra sites in Canada range from 2-3 ha"! at Devon Island, N.W.T. (Speller 1972), to 25 ha"! at Baker Lake, N.W.T., (Krebs 1964) and south- ern Hudson Bay (Brooks 1970), to 35-40 ha'!, also in southern Hudson Bay (Shelford 1943). Factors which may limit lemming distribution and abundance Bee and Hall (1956) have suggested that on the Arctic Slope of Alaska fluctuation in the population of collared lemmings seems to occur less often and to be of lesser degree than in the brown lemming. The microtine rodent popula- tion levels found in 1971-72 at Prudhoe Bay may indicate that popuiations of these small herbivores have always been low (relative to Barrow). The possibility that the low numbers in 1971-72 may reflect a trough (or fluctuation) in a lemming cycle cannot yet be eliminated. No systematic trapping for microtines was done in 1973. However, live trapping efforts by D. Holleman over a 4-5 day period in mid-July 1973 at Prudhoe Bay suggest that numbers were similar to or, in some areas, higher than those reported there for 1972 (D. Holleman, pers. comm.). In July 1973, although he captured no lemmings in the temporary live traplines near the BP camp, Holleman captured five Djicro- stonyx on grid area Q, using the outer perimeter of 40 traps (of original 100 traps). On grid area S, using 90 of the original 100 traps, he caught eight Dicrostonyx. Three of the eight were small juveniles, which indicated recent, active repro- duction. Comparison of these 1973 numbers on grid area S with those found in mid-July 1972 (Table 1) suggests that, at least on grid area S, numbers of collared lemming were higher in 1973. But this number does not exceed the highest found on grid areas P and QO in 1972 (Table 1). Holleman found no brown lemmings at any of the trapping sites. If lemming populations around Prudhoe Bay always remain relatively low, perhaps the most important factor may be the presence and the movement during the summer of caribou in the habitat of the lemming. Although they do not give any quantitative data from their observa- tions of collared lemming communities on the North Slope of Alaska, Bee and Hall (1956) claim that in certain areas the caribou controls the lemming population. At Barrow, where high populations of lemmings occur regularly, cari- bou are not an important element in the tundra ecosystem. At Prudhoe Bay, caribou annually migrate into the area in June, graze the area until September, and migrate out again to win- tering grounds (White et al., this volume). In 1972, between 30 June and 30 July, at least several thousand caribou moved across the area near Prudhoe Bay which included the live trap- ping grid sites in the present study (White et al., this volume). On 10 July 1972, 1,600 caribou were seen slowly traversing the area which in- cluded our lemming trapping grids, during a 141 period of several hours, grazing intermittently as they moved. MacLean (pers. comm.) reported that the passage of large numbers of caribou, as was seen at Prudhoe Bay in mid-July 1970, resulted in heavy grazing pressure on the vegeta- tion as well as severe physical disturbance from trampling. It is reasonable to assume that the impact of these large herbivores on the local lemming populations through competition for food and space and through physical disturbance or destruction of habitat may be great. However, this remains conjecture until clarification by further studies. In addition to the probable effect of caribou on depressing lemming population numbers, cer- tain predators may play a significant role in affecting lemming numbers (Pitelka 1957, Maher 1970). No quantitative data are available for avian predators (Norton et al., this volume) or for mustelid predators at Prudhoe Bay. The arctic fox (Alopex lagopus) may prey upon a significant portion of the available lemmings (Underwood, this volume). During the winter of Table 3 Density estimates for collared lemmings on three grid areas near Prudhoe Bay. Numbers in parentheses are the actual number captured on grid area. June July August 1971 1971 1971 Grid P* (low relief 0 0 0 polygons and tussocks) Grid Q* (low relief 2.2(2) 0 0 tussocks) Grid S* (shallow pingo 0 0 0 and surrounding area of very low relief tussocks) +Numbers ha | mid-June early July late July mid-August 1972 1972 1972 no72 7.4(8) 10.2(7) 3.3(2) 0 4.3(5) 6.6(5) 5.3(4) 0 1.6(1) 0 3.3(2) 1.6(1) “Grid area = 0.25 ha; effective trapping area estimated as follows to compensate for lemming movements (re: Brooks and Banks 1971). See methods section for further explanation. adult and subadult females probably without homesite adult and subadult pregnant females probably with homesite; and juvenile females subadult and juvenile males adult males 2.89 ha (60 m strip) 0.61 ha (14 m strip) 0.61 ha (14 m strip) i 10.0 ha (134 m strip) +Values are estimated minimum number of animals present per effective trapping area. 142 1971-72 a deliberate trapping program was con- ducted around Prudhoe Bay to reduce the popu- lations of arctic fox (W. Hanson, pers. comm.). Perhaps this reduction of canid predators facili- tated the increase in collared lemmings found in the summer of 1972. The impact of several years of human activ- ity in the area on the populations of microtine rodents remains to be determined. It is conceiv- able that the elevated road systems, which facil- itate field studies, have modified drainage pat- terns and altered the habitat conditions. Assess- ment of the significance of this disruption to the reproductive success and survival of local popu- lations requires further studies both near Prud- hoe Bay and in areas of the coastal tundra yet undisturbed by man. Conclusion The impact of the lemmings at Prudhoe Bay on the net primary production and upon the integrity of the tundra habitat would appear to be very small compared to that of lemmings at Barrow if the population numbers of these small herbivores normally remain as low as found in 1971 and 1972. Acknowledgments This research was supported by the National Science Foundation under Grant GV 29342 to the University of Alaska. it was performed under joint sponsorship of the International Biological Program and the Office of Polar Pro- grams and was directed by the U.S. Tundra Biome. Logistic support at Prudhoe Bay was made available through a grant to the Tundra Biome Center, University of Alaska from the Prudhoe Bay Environmental Subcommittee. | am grateful to the late Scott Parrish for his assistance in logistics as site coordinator at Prud- hoe Bay. | would like to thank Wayne Couture and Thomas Lahey for able field assistance, and Dr. Stephen F. MacLean, Jr. for helpful com- ments. References Batzli, G. O. (In press). The role of small mam- mals in arctic ecosystems. Submitted to: Small Mammals, Their Population Structure and Impact on World Ecosystems. 1IBP Series, Cambridge University Press. Batzli, G. O. and F.A. Pitelka. (1971). Condi- tion and diet of cycling populations of Cali- fornia vole (Microtus californicus). J. Mam- mal., 52(1);141-163. Bee, J. W. and E. R. Hall. (1956). Mammals of Northern Alaska. University of Kansas, Mus. Nat. Hist. Misc. Pub. 8, 309 pp. Brooks, R.J. (1970). Ecology and acoustic behavior of the collared lemming (Dicro- stonyx groenlandicus) (Trail). Ph.D. thesis. University of Illinois, 299 pp. Brooks, R. J. and E.M. Banks (1971). Radio- tracking study of lemming home range. Commun. Behav. Biol., 6A, 1:1-5. Brown, J., R.K. Haugen, and S. Parrish (This volume). Selected climatic and soil thermal characteristics of the Prudhoe Bay region. Burt, W. H. and R. P. Grossenheider (1964). A Field Guide to the Mammals. Houghton Mifflin Co., Boston, 284 pp. Krebs, C. J. (1964). The lemming cycle at Baker Lake, Northwest Territory, during 1959-62. Arctic Inst. No. Amer. Tech. Pap. No. 15, 104 pp. Maher, W. J. (1970). The pomarine jaeger as a brown lemming predator in Northern Alas- ka. Wilson Bull., 82:130-157. Neiland, B.J. and J. R. Hok (This volume). Vegetation survey of the Prudhoe Bay region. Norton, D. W., |. W. Ailes, and J. A. Curatolo (This volume). Ecological relationships of the inland tundra avifauna near Prudhoe Bay, Alaska. Pitelka, F. A. (1957). Some aspects of popula- tion structure in the short term cycle of the brown lemming in Northern Alaska. Pages 237-251 jn Cold Spr. Harb. Symp. Quant. Biol., Vol. 22. (1973). Cyclic pattern in lemming populations near Barrow, Alaska. Pages 199-215 jn Alaskan Arctic Tundra (M. E. Britton, ed.). Arct. Inst. North Amer. Tech. Pap. No. 25. Schultz, A. M. (1969). A study of an ecosystem: the arctic tundra. Pages 77-93 in The eco- system concept in natural resource manage- ment (G.Van Dyne, ed.). Academic Press, NY. Shelford, V. E. (1943). The abundance of the collared lemming (Dicrostonyx groen- landicus) in the Churchill area, 1929 to 1940. Ecology, 24:472-484. Speller, S.W. (1972). Biology of Dicrostonyx groenlandicus on Truelove Lowland, Devon Island, N.W.T. Pages 257-271 jn Devon Island |.B.P. project, high Arctic ecosystem (L. Bliss, ed.). University of Alberta. 143 Underwood, L. S. (This volume). Notes on the Arctic Fox (Alopex lagopus) in the Prudhoe Bay area of Alaska. Webber, P. J. and D. A. Walker (This volume). Vegetation and landscape analysis at Prud- hoe Bay, Alaska: A vegetation map of the Tundra Biome study area. White, R.G., B.R. Thompson, T. Skogland, S. J. Person, D. E. Russell, D. F. Holleman, and J. R. Luick (This volume). Ecology of caribou at Prudhoe Bay, Alaska. 144 Adult arctic fox in summer pelage de- fending aden site at Prudhoe Bay. 145 Notes on the Arctic Fox (Alopex lagopus) in the Prudhoe Bay Area of Alaska LARRY S. UNDERWOOD Naval Arctic Research Laboratory Barrow, Alaska 99723 Introduction This report is the result of some observations on the den site ecology of the arctic fox, A/opex lagopus. The purposes of the study were to assess the possible effects of this carnivore on small mammal populations in the Prudhoe Bay area and to gather baseline data on the arctic fox population in a portion of the Alaskan North Slope that will probably experience a consider- able increase in human activity in the near future. Data were collected on the location and topography of den sites, signs of food items associated with the dens, and behavior of pups at the den site. Study Area The study area consisted of Point McIntyre, at the northwest corner of Prudhoe Bay, and the Deadhorse area, located about 30 km inland. Both of these locations are considered to be part of the Prudhoe Bay area. The terrain is a typical Alaskan coastal plain, with numerous lakes and ponds; wet meadows, and slightly elevated beach, bank, and hummock areas. The soils and vegetation are also typical of the Alaskan coastal plain and are discussed elsewhere in this volume (Everett; Webber and Walker). Approximately 150 species of birds nest in this area during summer months. Many species of waterfowl and shorebirds, and two species of passerines (Lapland longspur and snow bunting) are present in relatively large populations (Norton, this volume). Mammal populations apparently are less reli- ably present. While bands of caribou (Rangifer tarandus granti), varying from a few individuals to several hundred, are common in the area, they may be absent at a given time (White et al., this volume). Small mammals consist of an apparently expanding population of arctic ground squirrels (Cite//us undulatus) and a rela- tively low level population of lemmings (Feist, this volume). Grizzly bears (Ursus horribilis), grey wolves (Canis /upus), and 13 other species are occasionally reported. (Bee and Hall 1956). Methods In the summers of 1971 and 1972, data were collected during a series of 3-day field trips. More extensive observations were made within a 3-week period in August 1972. As soon as dens were located, each site was described and mapped (Table 1). Carcasses and other signs of food were noted but left in place 146 at each den site. Fresh fecal pellets were collect- ed for later analysis of prey species content. Behavioral data were collected during three 6-hour observation periods from tent or truck blinds located several hundred meters from the den sites. Results A total of eight arctic fox dens have been located in the Prudhoe Bay area. Six of these dens are within 2.5 km (four are within 100-200 m) of the road system that was constructed in the area in 1968-70. The two dens located near Point McIntyre are in an area of low level human activity. Four of the dens are associated with pingos (geomorphic structures resembling small hills) ranging in height from approximately 2m to 9m in the Prudhoe Bay area. These structures, which are formed from the refreezing of lake bottoms following drainage, have a core of segregated ice. Dens near the tops of these structures have a commanding view of the sur- rounding tundra. The remaining dens are also located in rela- tively high, dry ground. Two of them are in ridge banks which are probably the banks of ancient, drained lakes. The vegetation at all den sites was considerably more robust than that of the surrounding territory and ‘‘greened up” noticeably earlier, indicating a richer soil and more favorable growing conditions for plants. Following the age classification system of Chese- more (1967), it was determined that all of the dens located ranged from young to mature. Den site DH4, located in a large pingo nearly 9m high, has two den systems. Although both were utilized by the pups, the one near the top with 10 entrances seemed to be used preferentially. In the 1971 summer season, five dens were examined, two of which supported young. At den site DH3, at least two young were heard, but apparently the litter was moved during the night following discovery, before an accurate count of the pups could be made. In 1972 eight den sites were examined, and four contained pups. It is likely that two of these dens contain- ed pups from the same litter. After several days of observation at site DH3, the litter of three apparently disappeared. The following day a new den containing three pups was discovered (den site DH6) in a riverbank not far from a well-traveled road. Although the den faced away from the road and could not be seen easily the pups were quite obvious when active. It is doubtful that the den could have existed all summer without being noticed. For the four litters observed during the 2-year period in which accurate counts could be made, the average litter size was 5.5. This is somewhat smaller than the average number of seven reported by MacPherson (1969) for arctic foxes in the Lake Baker region of Canada. Table 1 Densities in the Prudhoe Bay area Code Facing Approximate No. of No. of pups number! Location direction dimensions entrances 71 72 DH 1 Teg. NW. 7.5x 4.5m 15 none none DH 2 1.9 N 15.3x 9.9 50 5 10 DH 3 8.7 Ss 18.0x14.1 18 2(?) 33 DH 4 20.4 E 9.0x 9.0 10 4 E 4.5x 3.0 7 DH 5 21.4 n/a? n/a 25 none DH6 10.3 n/a n/a 10 33 MI 1 23.5 E 14.0x 4.0 56 none none MI 2 21.4 SE 8.0x 5.0 8 none none 1. DH refers to Deadhorse area; MI refers to Point McIntyre area. 2. Distance in kilometers from Deadhorse air terminal. 3. Probably same litter. See text. 4. n/a indicates data not available. The average number is increased consider- ably by the litter of 10 observed in 1972. Curiously, the animals in this litter were only approximately one-fourth grown in late July, while all other litters observed were nearly three- fourths grown. It is not known whether the animals were small because they had been born abnormally late in the season, or because the adults were not supplying them with enough food. However, their behavior appeared normal, and the three individuals that were trapped and examined seemed to have normal alertness, ‘‘fat- ness,’’ and quality and thickness of pelage. Behavioral Observations. Adult foxes were encountered relatively infrequently—only four times during approximately 50 visits or observa- tion sessions at active dens. The earliest of these encounters occurred on 12 June 1972. Upon initial examination, no foxes were in evidence, although fresh diggings and patches of molted fur were associated with several of the den entrances. After several minutes, an adult fox exited one of the entrances and quickly left the den area. Approximately 10 minutes later, the fox returned and attacked the observer as he tried to retrieve an object deep in one of the dens. The attack consisted of grabbing and jerking the observer’s hair. Thereafter, the fox approached from the rear to within a meter of the observer several times, and was noticeably aggressive (i.e., threat displays, vocalizations and snapping). As the observer left the den site, the fox reentered the den. No pups were seen or heard, but six weeks later a litter of three pups which were more than half-grown were ob- served. The second adult fox was encountered on 20 July 1972. Carrying two brown lemming car- casses, it approached two observers sitting quiet- ly on a den site. At a distance of approximately 9m, the adult became aware of the observers, dropped the lemmings, barked, picked up the prey, ran behind a small hummock, and buried the prey under a light coat of moss and lichen. The fox then approached the den aggres- sively, but with less intensity than in the en- counter described above (i.e., the second adult approached the observers less frequently and never closer than 4m). The fox seemed more defensive of the prey than the den site. The third encounter occurred on 21 July 147 1972. An adult fox observed the approach of two observers, barked once, and left the den site when they were within 45m of it. The adult moved off for approximately % km, hid behind some relatively high tundra grass, and observed the den. The fox soon became distracted by a golden plover, which he unsuccessfully tried to capture. The fourth encounter occurred on 3 August 1972 at den site DH6, when an adult was observed for 4% hours. Behavior consisted almost entirely of resting approximately 15m _ from the den site. During this period, a person who is not associated with the project approached the den to take photographs. The adult fox sat up and watched the person, but was not aggressive, and returned to a resting position as soon as the individual left. One of the pups that was playing actively in the area approached the adult fox only once. The adult snapped and growled, and the pup moved off. It appears from these limited data that the adults become less attached to the den as the litter matures. Reaction of adults to the pres- ence of humans in the den areas seems to progress from strongly defensive and aggressive in early June to nearly indifferent in early August. Casual human activity in the den area does not appear to seriously inhibit litter raising. On the other hand, frequent human activity may cause the adults to move the litters to new locations. Pup behavior was observed for a total of 33 hr, 44 min, during approximately half of which time the pups were inside the den. When out of the den, the pups rested half of the time (sleep- ing, lying, sitting, standing, and often staring out across the tundra), and were active for the other half (walking, running, playing moderately or intensely). During active periods, the pups explored the den site and surrounding area. Solo play consisted of pouncing on grass clumps and other objects in the den site area and occasional- ly tossing objects into the air. Group play, which rarely involved more than two interacting indi- viduals, often consisted of chases and wrestling. Wrestling matches were usually preceded by a “tail display’’ (upright tail, arched back, side- ways walk), followed by a quick pounce by the displaying individual onto the more passive one. Wrestling consisted of rolling and biting in the 148 region of the back of the neck and, less fre- quently, the tail and legs. The data are too meager to identify well- defined patterns in pup activity. However, it appeared that early morning, early afternoon, and evening were relatively quiet, while late morning and late afternoon were active periods. Activity seemed to be inhibited by inclement weather and mcsquitoes. Prey species utilization. |n marked contrast to similar data collected from den sites in other areas of the North Slope in past years, where as many as 30 lemming carcasses have been found associated with a single den, the amount of prey sign found associated with the Prudhoe Bay dens in 1971-72 was disappointingly sparse. This was probably a result of the relatively low popula- tion level of lemmings in these years. Prey signs consisted primarily of bits of lemming fur, par- tially eaten lemming carcasses, isolated feathers, and eggshells. The most significant observations occurred on 22 July 1971 at den site DH2, when one whole and from one to three broken swan eggs were found which had been brought to the den the previous night. All signs of the eggs had disappeared 24 hours after their discovery. A large wing, probably of swan and partially desic- cated (i.e., not freshly killed), was brought to the den, and the pups fed on it. Food items that could positively be identified were lemming, fledgling snow buntings, fledgling shore birds and swans. Several old caribou bones and antlers were associated with the dens, and were occa- sionally gnawed on by the pups, but were doubtless of small nutritional value. The age of fecal pellets of arctic fox can be determined by noting color. Fresh scat is usually shiny, black, and moist. Within 24 hours of production, barring rain or heavy fog, the pellets tend to dry out, but retain their color. After about 6 weeks, the pellets begin to show signs of greying, and become dark grey after about 3 months. Pellets that have over-wintered are gen- erally white or light grey. Thus, it is possible to distinguish scat of the year from scat of previous years. Table 2 shows an analysis of prey content from scat of the year collected in 1971 at active dens in the Deadhorse area, and scat of the year Table 2 Contents of fresh fecal pellets Prey Deadhorse area Point McIntyre sign (n=50) (n=24) Small mammal 86% 75% Caribou 2 0 Ground squirrel 12 4 Birds 56 63 Insects 8 8 Plants 46 42 Nondigestible material 14 0 found at random in the Point McIntyre area, where no pups or adults were observed. Small mammal sign (either of the two lem- ming species), consisting of fur, long bones, skull parts, teeth, and whole paws, in that order of occurrence, were found in four out of five pellets. The differences between Deadhorse and Point McIntyre were probably not significant. Ground squirrel sign was relatively low. Both Deadhorse and Point McIntyre are approximate- ly equidistant from the nearest known ground squirrel colony. The occurrence of one sample of caribou hair may indicate some summer scavenging but, with caribou actively molting in the area during the summer, it seems likely that caribou hair could be ingested accidentally. Stephenson (1970) reports that arctic foxes did not take scavenge on St. Lawrence Island during the sum- mer, when both live prey and carcasses were available. The second most common occurrence in the pellets was bird sign found in more than half of the pellets. Signs consisted of mature feathers, in parts or whole, pinfeathers, eggshells, egg membranes, and hollow bones. No attempt has been made to identify the species of birds. The six samples of insects consisted of two partially digested bumblebees (Bombas), one set of cranefly (Tipulidae) wings, and three un- identifiable insect carapaces. Plant remains usually consisted of isolated plant fibers, but included a large number of Salix rotundifolia \eaves which, although com- mon in the area, are not as common as their occurrence in the pellets suggests. Nondigestible items included bits of plastic, rubber, cork, and wire insulation. It is tempting to conclude that the differences in nondigesti- bles found in the two areas, Deadhorse and Point McIntyre (Table 2), are related to the differences in degree of human activity. How- ever, it should be noted that in the Point McIntyre area, an abandoned DEW-Line site and the remains of oil exploration activities conduct- ed at a time when environmental issues were not as popular as at present, have resulted in at least an equal availability of nondigestible items in the two areas. Discussion During the breeding season, adult foxes ap- pear to spend large blocks of time away from the den site; they are infrequently seen in the denning area. These observations can be explain- ed if one assumes that breeding foxes occupy large, overlapping feeding ranges. The use of swan eggs as food for fox pups fits this assump- tion. During the summer of 1971, ornithologists were documenting the nest locations of birds in the Deadhorse area. It is doubtful that breeding swans, whose large size and white color make them quite conspicuous on the treeless tundra, could have escaped detection at the time the eggs appeared at the fox den. The nearest known swan nest, 13 km from the den site, was not predated during July 1972. Thus, in this case at least, adult foxes probably traveled more than 13 km to secure food for the den. The impact of foxes On populations of small mammals and nesting birds is probably spread over an area of at least 500 square km. It should be reempha- sized that the lemming population was relatively low during these years, which may have influ- enced the size of the feeding range. Considerably more data are needed on range size and prey species utilization before definitive statements can be made on the impact of the arctic fox on small mammal and bird populations. 149 Acknowledgments These observations were conducted in con- junction with a Barrow based research project sponsored through the Arctic Institute of North America (AINA) and the NSF Tundra Biome grant to the University of Alaska. Support at Prudhoe was provided by the Tundra Biome Center through Prudhoe Bay Environmental Subcommittee funding. References Bee, J.W. and E. R. Hall (1956). Mammals of Northern Alaska. University of Kansas, Mus. Nat. Hist. Misc. Publ. 8, 309 pp. Chesemore, D. L. (1967). Ecology of the arctic fox in northern and western Alaska. M.S. thesis. University of Alaska, 148 pp. Everett, K.R. (This volume). Soil and landform associations at Prudhoe Bay, Alaska: A soils map of the Tundra Biome area. Feist, D. D. (This volume). Population studies of lemmings in the coastal tundra of Prudhoe Bay, Alaska. MacPherson, A.H. (1969). The dynamics of Canadian arctic fox populations. Canadian Wild. Rep. Scr. 8, Can. Wild. Ser., Ottawa, 52 pp. Stephenson, R. O. (1970). A study of the sum- mer food habits of the arctic fox on St. Lawrence Island, Alaska. M.S. thesis. Univer- sity of Alaska, 76 pp. Webber, P. J. and D. A. Walker (This volume). Vegetation and landscape analysis at Prud- hoe Bay, Alaska: A vegetation map of the Tundra Biome study area. White, R. G., B. R. Thomson, T. Skogland, S. J. Person, D.E. Russell, D. F. Holleman, and J. R. Luick (This volume). Ecology of cari- bou at Prudhoe Bay, Alaska. 150 ¢ Institute of Arctic Biology, University of Alaska Weighing a tranquilized caribou at Prudhoe Bay. Kecology of Caribou at Prudhoe Bay, Alaska ROBERT G. WHITE, BRIAN R. THOMSON*, TERGE SKOGLAND**, STEVEN J. PERSON, DONALD E. RUSSELL***, DAN F. HOLLEMAN, AND JACK R. LUICK Institute of Arctic Biology University of Alaska Fairbanks, Alaska 99701 Introduction The U.S. IBP Tundra Biome study area at Prudhoe Bay, Alaska, is located on the northern coastal plain bordered by the Kuparuk River in the west and the Sagavanirktok River in the east. This same area is the site of oil exploration, and the road system which has been constructed for this purpose allows easy access to most of the area between these rivers and to approximately 7 km inland (Fig. 1). Prudhoe Bay lies on the periphery of the summer range of two large populations of bar- ren-ground caribou (Rangifer tarandus granti). The western part of the Arctic Herd may move into the area from the west in June-July (Hem- ming 1971), and occasionally the outer (west- ern) periphery of the Porcupine Herd moves in from the east. However, most movement into the Prudhoe Bay area is thought to be from a large central section of the Arctic Herd (Hem- ming 1971). These animals move through Anak- tuvuk Pass and down the Colville River, or through the Dietrich and Atigun areas and down the Canning, Sagavanirktok and Kuparuk Rivers (Hemming 1971; Gavin 1975) to graze on the coastal plains from late June through Septem- ber. There is also evidence of a small population which remains in the Prudhoe Bay area year- round (Child 1973; Gavin 1975). The summer vegetation of the Arctic tundra is thought to be of high nutritive value. Rapidly growing vegetation is of high soluble carbo- hydrate, soluble nitrogen (N), and phosphorus (P) levels because of the long daylight hours. Thus, the relatively short growing season is complemented by high relative growth rates. Since it is considered that summer nutrition is important in affecting the body condition of animals entering the winter, the quality and quantity of forage removed from the summer range is potentially important in affecting the productive performance of these caribou. This may be relatively more important to the calf crop, as growth rates of caribou calves are normally high, and any restriction in nutrition during this stage of rapid growth may lower the likelihood of surviving the winter. *Current address: Department of Forestry and Natural Resources, University of Edinburgh, Scotland, U. K. **Current address: Statens Viltundersokelser, Elgeseter gt. 10, Trondheim, Norway. ***Current address: Faculty of Forestry, University of British Columbia, Vancouver 8, British Columbia, Canada. ez There is increasing evidence that harassment by flying insects plays a major role in determin- ing the movement and activity patterns of Rangifer in summer. Harassment leads to an increased energy expenditure because of avoid- ance movements and a corresponding decrease in the time spent grazing. However, whether this perturbation can materially affect the amount of herbage removed during a summer period has not yet been determined. Finally, caribou may affect primary produc- tion through removal of preferred plant species and by trampling. Both natural (e.g., insect harassment) and human (e.g., construction of barriers) perturbations may cause temporarily high stocking rates, resulting in local overgrazing and physical damage from trampling. In extreme conditions, Overgrazing and trampling may de- crease the insulative effects of tundra vegetation, which would have long-term visual and topo- graphically harmful consequences. A recent report considers the effects of simulated pipelines on movement patterns (Child 1973), while the present report docu- ments the normal grazing patterns of caribou in the Prudhoe Bay area. The objectives of this study were: (1) to determine normal activity patterns of the resi- dent and transient caribou populations; (2) to document the effects of insect harassment on activity and movement patterns; (3) to deter- mine plant preferences by caribou in relation to vegetation phenology and nutrient content, and (4) to determine the amount of plant material harvested and returned to the ecosystem. Methods Source of abiotic data Daily observations of dry and wet bulb temperature (°C), wind speed (km hr''), wind direction (degrees true N) and atmospheric pres- sure (mmHg) were obtained from climatologic data recorded at the Deadhorse and Prudhoe Bay airports. These observations were recorded on a 2 hourly basis from 0500 to 1800 hr. Supplementary field observations of ambient temperature and wind speed were made with a hand held thermometer and anemometer at approximately 1.5 m from the tundra surface. Determination of caribou population composition In 1972 the study area was surveyed mainly from the road system (every 1-2 days), and four aerial surveys were made. In 1973 composition counts were made from the road system each 2-3 days. In road surveys, all animals within binocular (10x50) or spotting-scope (25x60) range were classified according to age (calf, yearling, and adult) and sex. In addition, notes were made on group aggregations, locations, and movement patterns. During periods of high insect harassment, caribou numbers, ages, and sex classes were also noted from a series of vantage points in the sand dunes associated with the Sagavanirktok River. Documentation of behavioral and activity patterns Observations on behavior and recordings of activity patterns were made as described for wild reindeer in Norway by Gaare et al. (1970) and Thomson (1971, 1973). Briefly stated, a suitable herd or group of caribou was located and, by following unobtrusively, observed for as long as possible. At 15 min intervals throughout this period, caribou were classified according to the number of individuals engaged in each of seven categories of activity (eating, lying, standing, walking, trotting, running, and other). Between these activity counts, observations were made on weather data, caribou behavior, movement pat- terns, and external disturbances. Similar and concurrent observations were made on grazing preferences, time spent on different plant com- munities, and monitoring of grazing intensity (Gaare et al. 1970; Gaare and Skogland 1971). Grazing intensity Previous workers have defined grazing periods in two ways; either the activity associat- ed with eating per se (Thomson 1971), or the activity associated with searching and eating (Gaare and Skogland 1971). In the present report, the former activity is described as eating, and the latter as grazing. Grazing intensity was estimated as the fraction of a grazing period that was spent in eating [i.e., grazing intensity = eating time/(eating time + searching time)] . Description of vegetation Following preliminary survey of the vegeta- tion, an intensive study was made by describing and estimating plant species composition in plots (33x100cm), as described by Gaare (1968). The 108 plots from the typical plains were analyzed with description of 5-15 plots per vegetation type. Plant groups were arranged into phyto-sociological vegetation types accord- ing to the European phyto-sociological system. Dominance, constancy, and Sorensen’s index of similarity were used to distinguish types (Dahl 1956; Grieg-Smith 1964; Hanson and Churchill 1961). Nomenclature follows Hulten (1968). Moss cover was not described in detail. * Tranquilizing caribou and field rumenotomy Caribou were tranquilized with 3 ml M99 (Etorphine), which could be counteracted with 3 ml of antidote M50-50 (Diprenorphine) [American Cyanamid Corp., Princeton, N. J.] at the end of the sampling protocol. Once the caribou was fully tranquilized, 3 ml of Aceprom- azine [Ayerst Lab, N. Y., N. Y.] was given intramuscularly, and field rumenotomy was per- formed using the first stage of a rumen fistula- tion technique as described by Dieterich (1975). This involved shaving the operating area, dis- infecting the site with Zepharin chloride [Winth- rop Lab., N. Y., N. Y.], and locating the rumen through a 5-7 cm incision. The rumen wall was sutured to the skin, and an incision was made through the rumen wall for collecting mixed rumen samples, using a plexiglass tube of 3.2 cm in diameter (O.D.) and 55cm in length. After sampling, the exposed edges of the rumen were folded into the rumen, and the rumen fistula was closed by suturing the rumen wall. Muscle tissue and skin was then sutured to close the incision. Care was taken to minimize spillage of contents, and the wound was dressed topically with Furacin Powder [Eaton Veterinary Lab., Norwich, N. Y.] to minimize infection. Long acting penicillin, 5m Longacil S [Fort Dodge Lab, Inc., Fort Dodge, lowa], was given intra- muscularly to provide long-term protection. Caribou from all five field rumenotomy opera- tions survived at least until the end of the study period (3 weeks). libs Description of reindeer Female reindeer of 2-5 yr of age were flown to Prudhoe Bay from the University of Alaska, Fairbanks. In 1972 two esophageal fistulated (EF) animals (Nos. 31 and 37), and two rumen fistulated (RF) animals (Nos. 10 and 12), were held in a small corral for the first week (July 6-10), until they were accustomed to being tethered and had adapted to the available herb- age. No supplementary feed was given after July 10. Body weight measurements were made in July. Following experience gained in 1972, only two animals (Nos. 9 and 31) were taken to Prudhoe Bay in the summer of 1973. Both were supplemented with 2.5-3.0 kg d'' Purina Cattle Starter No. 1 for the entire season, and body weights were recorded every 3 days (see below). During periods of severe insect attack, rein- deer were sprayed with insect repellant (“OFF,”’ S.C. Johnson and Son Inc., Racine, Wisc., or Insect repellant Type IIB, Federal Specification 0-1-503) and were tethered in the most windy areas or were allowed freedom of movement in the holding corral. Body weight determinations Estimates of body weights of caribou and reindeer were made using a system involving four bathroom scales. An army stretcher or a wooden platform (2.5x1m) was placed on the scales, which were then turned to zero. Tranquil- ized caribou were lifted onto the stretcher, and live reindeer were trained to stand on the plat- form while the four scales were read concur- rently. Reproducibility of the technique was + 1.0 kg. Esophageal fistula collections Samples from esophageal fistulated animals were collected over 10 or 20 min time periods. The esophageal plug was removed during a col- lection, and upon swallowing, egesta was extrud- ed through the fistula and collected in a plastic bag fitted with a liner of nylon mesh (10-12 threads cm''). The nylon mesh served to retain the forage and allowed saliva to strain into the plastic bag. This apparatus was fitted into a canvas bag (30x18cm) which supported the plastic bag and liner and which could be attach- ed to the neck of the reindeer. “This scheme of classification is compared with a more detailed study by Webber and Walker (this volume). 154 At the end of a collection period, the appa- ratus was taken from the animal, and saliva was forced from the forage sample by squeezing. Wet weights of forage and saliva samples were deter- mined, and the forage was subdivided for deter- minations of plant species composition, dry matter content, and chemical composition. Identification of plant material in rumen and esophageal egesta samples Rumen and esophageal egesta samples were preserved in 80% ethanol. Since chlorophyll is removed from plant parts by alcohol, identifica- tions were made within 2 days of sampling to determine live and dead plant parts. Samples in the preservative were added to an enamel tray (25x40 cm), and 200 point identifications were made with a binocular (x10) as described by Galt et al. (1969); Gaare et al. (1970); Gaare and Skogland (1971). For comparison with samples of rumen con- tents and esophageal egesta, the plant species composition of communities on which the ani- mals were grazing was also determined (see Description of vegetation, above). Estimation of plant biomass and primary production Biomass estimates were made by clipping all vegetation above the moss layer in 30x30 cm plots. Clipped vegetation was sorted into green (live) and dead material, weighed, and dried at 5021G: Above-ground vascular production was esti- mated through the season from changes in biomass; total yearly above-ground production was estimated, assuming that peak green biomass represents total annual production (Tieszen 1972). Chemical analyses Dry matter content of vegetation, rumen samples, and esophageal egesta samples were determined by drying to constant weight in a forced air oven at 40-55° C. Estimates of cell contents, hemicellulose, and ligno-cellulose in vegetation were made using the acid detergent/neutral detergent tech- nique of Goering and Van Soest (1970). Lignin content was determined on the acid detergent residue using concentrated H,SO, (Goering and Van Soest 1970). Estimation of /n vitro digestibility The two stage, micro-digestion, /n vitro tech- nique of Tilley and Terry (1963) was used to determine the approximate digestibility of forage samples. Rumen liquor for the first stage of the digestibility was obtained from tranquil- ized caribou and the rumen fistulated reindeer. Strained liquor samples were incubated anaero- bically with buffer and 0.5 g samples of forage. The second stage digestion with a pepsin-HCl solution was carried out as recommended by Tilley and Terry. Results Caribou numbers and populations composition at Prudhoe Bay The location of the study area at Prudhoe Bay relative to the river systems is shown in Fig. 1. The 300 ft (91.5 m) contour indicates the most northern limit of the foothills of the Brooks Range. The heavily shaded area repre- sents that area which could be surveyed from the road system at Prudhoe Bay. A map pre- pared from aerial photographs of this road net- work and gravel pads is shown in Fig. 1a, with individual study sites marked on the map. 5 | 1 /5f® 150° 143? 148° 197° Fig. 1. Location of study area relative to the drainage system of the Kuparuk and Saga- vanirktok Rivers at Prudhoe Bay. 149°00' Site no. Description la Location of reindeer corral 1972 1b Location of reindeer corral 1972 ZnS Dryas heath and Sa/ix rotundi- folia snowbed communities (Table 8, Table 12, Appendix Table 2) 4 Eriophorum marsh communities (Table 8, Table 12, Appendix Table 1) 155 ft c2v \ \ 7%) Designation on vegetation map 148°40' 148°20' Designation on vegetation map Site no. Description Pe3;—;4 5 Dupontia fisheri brook meadow L3+L4 (Table 8, Table 12, Appendix Fy +F3, Fy9 Table 3) 6,7 Lake vegetation — Carex marsh (Table 8, Table 12) 8 Sand dunes Pyy3;4d > F 2,8 (Table 8, Appendix Table 4) C1—C5_—__ Location of caribou capturing activities (Table 11, Appendix Tables 5-10) Fig. la. Location of sites associated with reindeer and caribou studies at Prudhoe Bay in 1972 and 1973. S19 —F3,4 L6 +L13 or F,5,3 D15-+-D17 156 The number of caribou present in the Prud- hoe area varied daily depending on the extent of immigration into and emigration out of the area. Thus, in 1972 between eight and 1,500 animals were observed on any single day in the study area, and in 1973 between one and 130 animals. In both years maximum numbers occurred on days of insect harassment, and caribou were observed to move into the area. Lowest numbers were observed in insect-free periods, and fre- quently caribou were tending to disperse out of the area. In 1972 groups harassed by insects would move towards the coast; under severe harass- ment, large herds would assemble, particularly on the sand dunes and the sand or gravel banks of the river deltas. Herds moving under insect harassment would sometimes swim the Sagavan- irktok or Kuparuk rivers. In summer 1973 maximum numbers ob- served again corresponded with days of insect harassment (Fig. 2), but the large ‘‘invasions’’ did not occur. High water levels in the Sagavan- irktok and Kuparuk rivers conceivably could have inhibited movement into the study area in the upper reaches of the rivers. Large herds Harassment Severe ry la F | (0) 1600 1400 1972 3 1200 h 32 S 600 2 400 . o 3 = 3 200 Zz x! 2 | fe) co NS rn Feo er TN fat Severs Harassment 9 EMild_ A_Pao Wa V2a 2 200 1973 5 Oo Pot! Oo 25 30 5 10 15 20 25 30 S June July August Fig. 2. Relationship of caribou numbers and intensity of insect harassment at Prudhoe Bay. Caribou numbers were obtained from a census of caribou within binocular range of the road; 7, 2, 3; aerial surveys between coast and Franklin Bluffs. under insect harassment were observed 35 km inland on the moderate heights of the Franklin Bluffs (Gavin, pers. comm.). Population composition sample counts in both years were taken to be representative of the animals present in the Prudhoe Bay area, but not necessarily representative of any whole population, such as the Porcupine Herd, the Arctic Herd, or a “‘resident’’ Prudhoe Bay popu- lation. For 1972 a calf:female ratio of 67:100 was estimated. This estimate was based on an ob- served ratio of 51.2 +4.0 calves per 100 females plus yearlings (counts of 941 calves/1,831 fe- males + yearlings in 26 herds of size greater than 24 females + yearlings per herd) and an estimat- ed yearling: female ratio of 24:100 (counts of 22 yearlings/90 females). A male:female ratio of 101:100 was based on an observed ratio of 77 males per 100 females plus yearlings (counts of 1,103 male/1,429 females + yearlings). The near- ly equal sex ratio was the result of a large herd of more than 1,000, of which 60% of animals (excluding calves) were males, which were classi- fied as they moved into the area under severe insect harassment in 1972. From the fewer animals present in 1973, three separate counts of at least 120 animals found the calf:female ratio to be 31:100, the yearling:female ratio 25:100, and the male: female ratio 37:100. A comparison of the herd proportions re- corded at Prudhoe Bay with previous estimates of herd proportions is shown in Table 1. The proportion of calves in caribou herds at Prudhoe Bay (16-23% of the herd) is similar to the calf percentage (15-26%) noted for major counts on the Arctic and Porcupine Herds. When the herd proportion of calves is adjust- ed to a calf:female ratio, the data suggest that the survival of calves to the end of July 1973 at Prudhoe Bay was low compared with either the results for 1972 at Prudhoe Bay, or for the Arctic and Porcupine Herds in June. Moreover, the calf:female ratio of the Porcupine Herd in October 1972 (31:100), following a known high rate of mortality of calves in July and August, was the same as that for the Prudhoe Bay animals in 1973. Survival of yearlings was appar- ently similar for both years of the Prudhoe Bay counts and was slightly higher than that for the Porcupine Herd. Herd Table 1 Comparison of estimates of herd proportions (% of total number of animals) of Prudhoe Bay with estimates for the large arctic herds. Year Female Male Approximate 157 Shee eee a —a——[————— Prudhoe Bay 1972 34(100) 35(101) 1973 52(100) 19(37) Arctic 1970 40(100) 26(65) Porcupine 1972 - _ Porcupine 1972 July 52(100) 12(23) October 49(100) 28(57) Calves Yearlings no. classified Reference 23(67) 8(24) 2,632 This study 16(31) 13(25) 248 This study 19(47) 15(37) 242,000 Pegau and Hemming (1972) 24 = 50,000 LeResche (1973) 26(50) 9(17) 17241 Calef and 15(31) 9(18) 2,997 Lortie (1973) Values in parentheses are ratios expressed per 100 adult females. Group activity patterns of caribou In the 1972 season the number of individu- als in a group or herd variously involved in the activities of eating, lying, standing, walking, trot- ting, or running was recorded at 456 separate 15 min intervals. Activity of adults (female, yearling, and male) over the whole observed period averaged 48% eating, 28% lying, 4% standing, 14% walking, 5% trotting, and 1% running. The disproportionately few observa- tions on male activity, except under insect ha- rassment, make an accurate comparison with female activity times difficult. However, the contrast between adult and calf activity times was quantified after recording the activity with- in 15 groups (containing females, yearlings, and calves) over 4 insect-free days in late June 1972. The result is summarized in Table 2a; analysis of variance on the full data (Thomson 1974) indi- cates that females plus yearlings spend signifi- cantly more time eating than do calves, while the calves spend significantly more time lying, standing, trotting, and running. Only walking time is not significantly different between the calves and older animals. Calves at this age (approximately 2-4 wk by end of June) graze considerably more and lie less than do calves at 1-10 days of age (wild Table 2a Summary of activity patterns of female yearlings and calves during insect free periods (values are % of study period). Sex/age class Eating Lying Female-yearling 52.8 S2H7, (4.8) (4.5) Calf 2325 54.6 (5.9) (6.9) Comparison of classes X Xx Standing Walking Trotting Running 1.2 le 1.8 0.1 (0.9) (3.0) (1.3) (0.2) 4.7 10.9 4.5 1.5 (3.2) (4.4) (2.8) (123) X NS X X Value in parentheses is the standard deviation. A total of 15 groups were observed: three groups were observed for more than 6 hr duration; the remainder were observed for less than 6 hr and were combined into five groups according to date. Calves were 3-7 wk of age. NS, not significant; x, P<0.05. 158 Table 2b Comparison of activity patterns of calf and adult cohorts at Hardangervidda and Prudhoe Bay. Calves, Calves, reindeer caribou (1-10 d) (3-4 wk) Grazing 7% 24% Lying 66% 55% Standing 9% 5% Walking 12% 11% Trotting 2% 5% Running 2% 2% Suckling 4% <1% Reference: Hardangervidda Thomson (1973) (Table 2a) reindeer in Norway; Thomson 1973). The gradu- al development of the Aangifer calf activity towards an adult pattern is illustrated in Table 2b. Nursing behavior A total of 55 successful suckling events were observed over the 6 wk study period in 1972, 35% of which were timed at between 10 to 85 sec duration (mean 33.3 sec). At the start of the study, calves were approximately 2-4 wk of age, assuming calving to be approximately June 8 (Lent 1966; Calef and Lortie 1973), and they were suckled significantly (P <0.05) longer than calves at 6-7 wk of age (Table 3). These data confirm observations on wild reindeer in Nor- way and domesticated reindeer in Sweden. The general ontogeny of nursing behavior for mem- bers of the genus Rangifer is shown in Fig. 3. Unlike reindeer, in which a lactating female may nurse several calves at one event, only single nursing events were observed in caribou. In a separate study on milk production of reindeer (White, Holleman, and Luick, unpub. Table 3 Duration of single nursing events (4SD) of caribou calves at Prudhoe Bay. Age of calf Duration Significance of (wk) (sec) difference 3-4 36.0+7.3 P<0.05 6-7 26.7+4.4 Prudhoe Bay Adult Adult caribou reindeer (insect-free, July) (insect-free, August) 53% 49% 33% 30% 1% 3% 11% 14% 2% 3% <1% 3% Hardangervidda Thomson (1971) Prudhoe Bay (Figure 4) obs.), it was shown that milk intake of reindeer calves was 1.5-2 1d°' for the first 2 weeks of age, after which it declined exponentially, viz. M=2.1 Be 0.01 16A where M = milk intake (1d°') and A = age of calf (d). Insect harassment (a) Relationship of insect harassment with wind and temperature. Insect harassment was observed to have a dominant influence on cari- bou social behavior, as evidenced by changes in gregariousness, activity times, speed of move- ment, and habitat selection. The presence and degree of insect harassment on caribou could be recognized (and classified as moderate or severe) © Sweden, Espmark (1971) 100 OD Norway (Hardangervidda) @ USA (Prudhoe Bay) Interval 80 between successful : sucklings Duration (min) 4 of 60 300 suckling (sec) (ela! ) 40 200 20 100 (0) O (0) 4 8 l2 16 20 Approximate age of calves (wk) Fig. 3. Comparison of the ontogeny of suckling behavior in domesticated (0) and wild (Q) reindeer and caribou (@). WIND SPEED km hr! /mi hr! 40/25 14/15 IS) 40 45 50 159 Air temp.-measured in shade, at 20 cm above ground Wind speed-km hr! range, at 100 cm above ground Harassment WS l Severe se i Moderate i None 55 60 65 OF Ambient temperature ike) 2ORE Fig. 4 Relationship of intensity of insect harassment on caribou with ambient temperature and wind speed. from a variety of individual behavior responses, including tail wagging, ear flicking, head and body shaking, twitching, shuddering, leaping, and bounding, as described by Thomson (1971, 1973). Mosquitos (Aides spp) became active, and the first signs of caribou harassment apparent, as shade air temperature increased above 6°C under still air conditions. With increasing tem- perature, mosquito harassment of caribou be- came progressively greater, as did the mosquitos’ tolerance for wind. At shade air temperatures of over 13°C, usually on warm, sunny days, warble flies (Oedemageon tarandi) were observed to be active around caribou herds, causing avoidance responses typical of severe harassment. This relationship between intensity of insect harass- ment with ambient temperature and wind strength was quantified for the Prudhoe Bay area through frequent field recordings (Fig. 4). The regularity of the relationship made it possi- ble to predict the degree of harassment from prevailing weather conditions on any day. Unfortunately, the continuous data on air temperature and wind speeds at the small Prud- hoe Bay meteorological station did not corre- spond to the same parameters measured on the field, because wind speed near the ground was not measured, and because local site variations accounted for a considerable variation in tem- perature. However, as an approximate guide, if a maximum daily temperature of 8.5°C or over was recorded, a day of moderate insect harass- ment could be predicted. If the maximum was 13.5°C or over, a day with severe insect harass- ment was predicted. The number of days in which caribou would experience insect harass- ment as predicted from meteorological data is listed in Table 4. Also shown in Table 4 are estimates of the cumulative duration of harass- ment for 1972 and 1973. In all years, July is the peak month for insect harassment, with 20-25 days mild enough for harassment, during approximately half of which severe harassment on caribou can be expected. For mosquitos, the season extended 160 Table 4 Estimates of periods of possible insect harassment of caribou calculated from Prudhoe Bay weather data. Number of days when Cumulative duration of harassment was Period nil mild 1970 June 21 4 July 6 14 August 21 6 Summer Season 1970 48 24 1971 June 15 2 July 8 13 August 18 8 Summer Season 1971 41 33 1972 June 23 7 July 11 10 August 4 8 Summer Season 1972 38 25 1973 July 11 17 August 5 7 Summer Season 1973 16 24 insect harassment (hr) severe mild severe 0 - 10 130(17) 12(2) 0 48(17) 0(0) 9 91(12) 101(14) 2 53(18) 13( 4) 11 The index of insect harassment was estimated from temperature and wind speed records from the Prudhoe Bay weather station according to Fig. 4. Wind speed at 1.5 m from the ground (G, km hr! ) was used in the estimation and was calculated from the weather station wind speed records (W, km hr!) viz: G= 1.0 + 0.5 W. Value in parentheses is duration of harassment as a percentage of the total period (i.e., 744 hr in July, 288 hr in August). over nearly the whole study period from 25 June to 10 August, whereas warble flies were noted in suitable weather between 23 July and 15 August. (b) Effects of insect harassment on group size, composition, activity and movement. On cool, non-insect days in June, July, and August, caribou were typically segregated into female- yearling-calf groups and male groups (Table 5). These groups noted under insect-free conditions had a mean size of 22 individuals, with only four groups (3%) of over 100 (Table 6). However, under insect harassment, groups readily coa- lesced, resulting in both a significantly higher proportion of mixed groups (Table 5) and an increase in group size. The 92 insect-harassed Table 5 Effect of insect harassment on segregation of caribou into female-yearling-calf and male groups. Group Structure Segregated Integrated No insects 59 Nez, Mild and severe 39 26 harassment Chi-square test shows these differences be- tween level of harassment were significant (SZ = 5.18 at 1 d.f. P<0.05). Values shown are the number of groups in each category. groups noted had a mean size of 77, with 21 groups (23%) of more than 100 individuals (Table 6). Caribou which were not harassed typically would be dispersed widely in a loosely coordi- nated group, alternating periods of concentrated grazing with lying, and often meandering only a few km in 24 hours. Caribou under mild insect harassment, a situation indicated by frequent tail flicking and head shaking, would move closer together in an oriented group, walking or trotting as they grazed. In a resting period, the animals would lie and stand close together; lying animals would often jump to a standing position and shake or scratch themselves. Under severe harassment, large massed herds would be seen making long, rapid movements, during which individuals would occasionally pause to quickly eat, thenrunortrot to rejoin the general move- ment. Table 6 Effects of insect harassment on group size. Values shown are the number of groups noted in various size classes during the study period. Group size 1-10 11-50 51-100 101-500 500+ No insects 70 42: 11 4 0 Mild and severe 40 18 13 18 3 harassment The effect of increasing intensity of harass- ment on the activity budget was quantified and is illustrated in Fig. 5. Grazing and lying times declined markedly, and time spent standing en masse and in locomotion increased. These results parallel earlier findings for wild reindeer in Norway (Fig. 5). Attempts were made to document the speed of movement under different levels of harass- ment by relating distance covered to time taken. Under insect-free conditions, caribou groups averaged 0.53 km hr! over several hours of alternating active and rest periods (Table 7). At this speed, undisturbed groups would move an estimated 14 km per day. During insect harassment, the speed of movement of caribou depended on the time 161 Ti ne USA Norway Wel (Prudhoe Bay) (Hardangervidda) Summer 1972 Summer 1970 50 40 Se \ Eating 30 \ mane < \ pwalkiog m “Walking 20 \ =~ Trotting ph AS Pe i Lee ey rektion be n winegshinas LA unni wr Nook a 27S Standing g cee Ln “\Lying ax a Lying poeree Running nal None Mild Severe Insect Harassment None Mild Severe Fig. 5. Effect of insect harassment on daily activity patterns of caribou at Prudhoe Bay (this study) and reindeer at Hardangervidda, Norway (Thomson 1971). interval chosen. An insect-harassed individual or group was observed to run 25-35 km hr! over several minutes. Walking, trotting, or running by a harassed group averaged 8-16 km hr! over a longer interval (for example, during caribou movements along the Sagavanirktok River towards the coastal area). However, average speed of caribou movement was 3.14 km hr’! for periods of severe harassment, and 1.36 km hr! during mild harassment. The differences were significant (Table 7). At these speeds, a caribou group harassed for 8 out of 24 hours would move a distance of 14 to 42 km, an average of 28 km. Table 7 Effects of insect harassment on daily average rate of movement. Degree of fly harassment none mild severe Number of groups 13 12 8 Mean speed (km hr!) 0.53 1.36 3.14 t-test significance P < 0.05 POM P<0.01 162 (c) Habitat use. Observed movements of caribou under insect harassment were not ran- dom in the Prudhoe Bay area. With the first indication of insect activity, grazing caribou would orient into the wind, but would otherwise remain grazing on the flat plains which constt- tute their major habitat. However, in their graz- ing patterns, they would avoid marshy areas and the lush vegetation of lake edges where mosqui- tos were more troublesome. Marsh & lake Plains edge veg. veg. veg. tO Ce ee Se Increasing level of insect activity Gravel & sand Sand dune (no veg.) At an increased level of harassment, groups moved more quickly, heading toward areas of tundra with the least insect activity. Thus, inland groups moved north into the wind toward the coast, where the prevailing north wind reach- ed its maximum velocity. During this movement, caribou frequently moved along river beds and on the numerous game trails. In the coastal areas, the caribou would find optimum relief by lying or standing in the wind-oriented “‘gullies”’ of the sand dune area or on the extensive sand or gravel bars of the river deltas where lack of plant growth was not conducive to mosquitos, or even by standing in the open water of the rivers and the Arctic Ocean. If harassment was not too severe at the coast, the caribou would remain there, grazing on the plants of the dry sand dune areas. Under mild harassment, caribou would often remain on the flat plains which constitute the major habitat. As insect harassment declined, normally in association with a reduction in air temperature or an increase in wind velocity, herds would leave the coastal area and slowly move inland, with concentrated grazing and dispersal into smaller-sized units, and males and females in increasingly segregated groups (Fig. 5). Follow- ing several days of freedom from insect harass- ment, groups would continue to disperse inland out of the study area, but with the return of warm, windless weather, the groups would pre- dictably coalesce and move rapidly to the coast (Fig. 6). Influx of migrato: caribou in mid to Jate June f= Insect evoked movement ™ Slow dispersal (no harassment) Fig. 6. An assessment of the effects of insect harassment on observed movements of caribou in the Prudhoe Bay area. As an alternative to the use of coastal areas under fly harassment, males particularly, either singly or in groups, would often move onto the raised and bare gravel roads and pads of the oil development. Individual males could even be found standing or lying in the cool shade cast by the machinery and equipment around the camps. In 1973 higher winds associated with the Franklin Bluffs apparently attracted caribou seeking insect-relief areas. As discussed above, Prudhoe Bay lies in the overlap between the summer ranges of two major caribou populations which make tradi- tional seasonal movements and migrations (Hem- ming 1971). However, local summer movements and use of the tundra by caribou in the Prudhoe Bay area appeared to be dependent on the degree of insect harassment and, in insect-free periods, on the caribou’s feeding preferences within the successional phenology of vegetation types (see below). Classification of vegetation into phyto-sociological units Fig. 7 shows diagrammatically the approxi- mate pattern of vegetation types in the study area; six major terrestrial vegetation types (lle) 163 Fig. 7. Diagrammatic representation of Prudhoe Bay vegetation types in rela- tion to moisture gradient and elevation. Numbers in brackets are vegetation types in accordance with the Webber /Walker scheme (this volume): Webber/Walker Vegetation Continuum Type 1 Type2 Type3 Type4 TypeS Type6 ~ Type? Normal moisture ———EE gradient increasing wetness Sand dunes Type 15 Type 16 Type 17 Streams Type 13 Type 12 Pingos Type 10 Snowbanks Type 9 Frost boils Type 8 The numbering of the sand dune communities is tentative and will probably change following more extensive mapping in the dunes. The following is a brief description of the current types: Type 15 — Pioneering communities consisting mainly of E/ymus arenarius, Artemisia spp and Salix ovalifolia. Type 16 — Drier communities on stabilized dune sand which has developed polygonal patterning. This type is similar to Type 2 and 3 but with much more Sa//x ovalifolia and Artemisia spp. Type 17 — The wetter communities in the dunes which are similar to Type 4 but with abundance of Salix ovalifolia. Sand Dunes Vegetation Key: Webber/Walker Scheme for Prudhoe ae Bay (Key to the most common vegeta- ovalifolia tion types of Prudhoe Bay) Elevation ti7y_ol tet 1. Lichens abundant Poe | Lichens rare 3: Standing Carex Eriophorum | Dryas Solin 2. Many fruticose and crust lichens INAFE 1 Water | aquotilis | angustifolium| integrifolia | rotundifolia | Rive Mostly only fruticose lichens TYPE 2 VEG) Pe ai pee) Sa See 3. Dryas and/or Salix spp. abundant nNAre 3 | | Duportia \ Bro Dryas and/or Salix spp. rare 4. Perea as paar 4. Mosses rare TYPE 6 ey Creek Mosses abundant 5. | ee 5. Drepanocladus species dominant TYPE 4 3 a = Increasing Wetness + Scorpidium scorpioides dominant iN RES [ ] Vegetation type- Webber/ Walker Scheme were distinguished using Sdrensen’s index of similarity: oe 2.c.100 S atb where a is the number of plant species in a stand of vegetation with a constancy 250; 6 is the equivalent value for the compared stand; c is the number of shared species. The mean index of similarity between stands within types was 64.7 (SD = 9.1) and between vegetation types 24.7 (SD = 17.6). The vegetation types correspond to the criteria of associations, but a formal classifi- cation was not attempted due to lack of data on the cryptogams. Vegetation types were named after the dominant species in each type. Vegetation distribution in the study area was surveyed in four ground transects covering the land area between lakes. Lakes and sand dunes were recognized from aerial photographs and maps, and their distribution assessed in five map transects. The results of the ground transects are shown in Table 8, and the combined ground and aerial transects, in which free-water cover was deleted, is shown in column 8 of Table 8. Also shown in Table 8 are the same vegetation types with their appropriate designation, according to Webber’s vegetation map for Prudhoe Bay (this volume). Caribou grazing patterns and dispersion (a) Caribou preference for vegetation types. Groups of caribou were observed for 10 min 164 Table 8 Percentage distribution of vegetation types along four transects of 15,168 m in total length. Also shown is the distribution across sand dunes excluding free-water cover % of land cover). Designation from Vegetation types vegetation map~ Dryas integrifolia heath type F,—>F3 Salix rotundifolia snowbeds Fyw9 Dupontia fisheri brook/meadow S12>F 3,4 type Eriophorum angustifolium polygon marsh type Pi43; 4d >F 2,8 Carex aquatilis marsh type Sand dunes (Salix ovalifolia) Water Roads Lg>L,, or aeons D15—D17""* % of Webber/Walker Transect land scheme 1 2 3 4 Mean(SD) cover Types 1,2,3 6 5 1 8 5(2.4) 5 Type 9 8} 05 — = 0.2 - Type 12 4 2) — Ald 4(4) 4 Type 3 72 56 46 30 51(15) 52 Types 4,5,6 8 23 41 50 31(16) 31 Types 15,16,17 = = 9 13 11 1 8.5(4) = 1 1 1 ~ 0.7 - “See prefix and suffix descriptions, Webber and Walker (this volume). ee . Tentative numbers. Transects were established in mid- to late July 1972. SD, standard deviation. intervals to determine the vegetation types through which they grazed. In late June a preference was shown for the Dryas heath and the adjacent snowbeds. These communities were slightly elevated, were well drained, and provided an early source of cal- ciphilic vegetation composed of Carex scirpoidea on the heaths, with herbs, flowers of Dryas integrifolia and Saxifraga oppositifolia, \ichen and Salix rotundifolia in the more protected depressions. Later in the season (after mid-July), the Dupontia fisheri wet meadow was preferred, perhaps because it had then contained a rich variety of herbs, salices, and grass-like species. The combined observations of caribou dis- persion in relation to plant vegetation types for the 1972 field season are shown in Table 9. Thus, 42% of all animals were noted on the Eriophorum marsh, the most available com- munity (52%); almost 20% were grazing the Dryas heath/Salix rotundifolia snowbed com- munity, and 12 to 14% were grazing the other communities. An assessment of caribou disper- sion in relation to vegetation type was also available from the behavior study, and the distri- bution was confirmed. For example, 59% of caribou grazed the Eriophorum and Dupontia types; 15% grazed the Dryas heath and snowbed types; 8% grazed the Carex marsh, and 18% grazed the sand dunes. The latter observations were confined to periods of insect harassment. When distribution is expressed as a function of the availability of the vegetation type in the area, it is clear that the Dryas heath/snowbed and the Dupontia wet meadows’ were used at almost 3 times their availability and the sand dunes at almost 2 times their availability, while the main community, the Eriophorum marsh, was used almost in proportion to availability. An apparent discrimination against the Carex marsh was noted. However, the Carex marsh was not available for grazing early in the summer because of the high water levels in it, which suggests the type may not be as available as shown in Table 7. From the above discussion, it is clear that the ratio of caribou dispersion in relation to vegeta- tion type (Table 9, column 13) should not be interpreted as showing grazing preferences with- out accounting for the seasonal trends in the vegetation types with respect to phenology, and the probable presence of a prime mosquito habitat. Thus, the evident lack of preference for 165 Table 9 Dispersion of caribou on vegetation types in relation to group size. Values given are percentages of observations for the particular group or period. Caribou group size 1-10 11-20 21-99 Vegetation types N % N % N % Dryas integrifolia 7 832) $6 4 18:25 a 35.5 heath/Sa/lix rotun- difolia snowbed Dupontia fisheri 9 10:6: 7 | 21.22 3 9.7 brook meadow Eriophorum angus- 44 51.7 11 33.0.° 9 | 29:0 tifolium marsh Carex aquatilis ly 20:0. 4 asl 2 6.5 marsh Salix ovalifolia 8 G4 5. 15.2 6 19.4 sand dunes 85 100.00 33 100.0 31 100.0 17 29 Grazing dispersion Availability relative to 100 All groups of vegetation vegetation type (%)** availability * ** % N %*(A;) (B;) (%) (X;) 13:8 | 28 18.3 5 35.3 13.) 24 14.2 4 35.4 58.6 81 41.8 52, 8.1 _ 23 ZS) 31 4.1 103° 22 132 8 171 100.0 178 100.0 100 100.0 “Mean percentage normalized to give a total of 100% for all vegetation types. **From Table 7. ***Values (X;, column 13) were calculated from the normalized mean for all groups (Aj, column 11), the percentage distribution of vegetation type (Bj, column 12), where i = vegetation type (i = 1, 5), i.e. X; = Aj/Bj x 100./DA;/B;. the Eriophorum and Carex marsh types could be due to their higher water table, which would be associated with mosquitos, and to the high proportion of standing dead plant material and mosses. When utilizing the Eriophorum angusti- folium marshes, caribou characteristically grazed the raised micro-ridges on the polygons, where there was a richer plant growth than in the stagnant polygon trough. The distribution of caribou on the vegeta- tion types in relation to the caribou group size is also shown in Table 9. Most observations for the small group sizes (1-10 and 11-20 animals per group) were made on days when insect harass- ment was minimal or absent. Groups in excess of 100 individuals were noted under conditions of severe insect harassment (Table 6) and when grazing adjacent to the sand dunes after a period of severe harassment. During periods of mild to severe insect harassment, no animals were ob- served grazing the Carex marsh, while at other times the distribution of animals was similar to that noted for periods of zero to mild insect harassment. (b) Botanical composition of EF samples. The reindeer were taken to the general locality of each vegetation type and allowed to graze freely while attached to a 20 m rope. Site 1: July 4-6. This site was located in the E. angustifolium polygon marsh type. Seven EF samples were collected. The results of the botan- ical analysis are shown in Appendix Table 1. E. angustifolium, with a mean of 45.6% green tissue, constituted the largest portion of the contents at this time. Also, a large portion of dead tissue was collected. Of the total collection of E. angustifolium, 62% was green and 38% dead. Site 2: July 15-16. This site was located on the raised dry heath beds along the river banks. Dryas integrifolia was the principal constituent of the heath, and Sa/ix rotundifolia dominated the adjacent snowbeds. Although these vegeta- tion types were distinguishable, their proximity to each other and overlapping occurrence made grazing so overlapping that they were considered as one unit. Five EF samples were collected 166 from this site. The results are shown in Appen- dix Table 2. Carex scirpoidea from the dry heaths and S. rotundifolia from the snowbeds constituted 26.4 and 13%, respectively, of the sample compositions. Also noticeable were lichens, mainly 7Thamnolia vermicularis, which comprised about 5.7% of the diet. The relation between green and dead grass-like species was 65% green Cyperaceae and 35% dead Cyperaceae. Site 3: July 23-27. This site was located in an area described as a wet meadow with a high water table early in the season, but drier with emerging green by the end of July. It was typically situated along brooks on sandy ground with a rich growth of willows and herbs. The dominant species was Dupontia fisheri. This vegetation type is situated close to the water, intermediate between the Eriophorum angusti- folium type and the Carex aquatilis types. Six EF samples were collected from this site. Appen- dix Table 3 shows the botanical composition: grass-like plants (mainly family Cyperaceae) con- stituted 42.6% of the sample, with C. aquatilis and &. angustifolium at 11.7 and 17.1%, respectively. Salicaceae constituted 24.7% of the samples and herbs 18.3%. A wider variety of plant groups was chosen from this than other sites, and the amount of dead material was very small. Site 4: July 28. This site was located in the sand dunes area near the coastline. Two EF samples were collected (Appendix Table 4), Sa/ix ovalifolia at 79% was the main plant species. Most scattered herbs were picked. Reindeer fed by moving from one plant cluster to another. A low content of dead material was noted in the samples. Direct comparison between compositions of EF egesta and available herbage was difficult because reindeer fed by slowly walking and nibbling at the ground cover in a non-random fashion. During a collection period, the animals might move over several vegetation types. Also, the distribution of plant species within vegeta- tion types was commonly clustered, and a valid quantitative evaluation of plant species selection is rather dubious. However, 33x100 cm plots were subjectively laid out and analyzed along the approximate route of movement of the reindeer after the termination of EF collections. Eriophorum-angustifolium (marsh) Vi. oD Carex aquatilis (marsh) os Dryas integrifolia (heath) Qh) es o_O Dupontia fisheri (brook meadows) mW Salix ovalifolia (sand dunes) (%) N oO (o>) je) NO j=) CHOMMEDRONSHINt smOnn S (>) oO 60 Shrubs Sedges/ Herbs Lichen Mosses Litter grasses ZZ [ea Vegetation plot Fistula sample Fig. 8. Frequency of occurrence of plant groups in esophageal fistula samples compared with vegetation grazed by reindeer. Fig. 8 shows the approximate preferences for the systematic plant groups from each study site. Each bar of the histogram represents the percentage composition of the particular plant groups from each sample. The horizontal cross- lines represent the median value. Gaare (pers. comm.) suggested the use of the median value as a better representation of the average than the mean when outlying observations occur, as in this case. From three study sites there was a median preference for the grass-like groups, respectively from the D. integrifolia-S. rotundifolia type, the E. angustifolium type, and the D. fisheri type. From the S. ovalifolia sand dunes there was preference for S. oval/fo/ia. f Table 10(a) shows the overall composition of 20 EF samples irrespective of vegetation type. Collectively, they constitute the main compo- nents of the diet in early, mid- and late July. 167 Table 10 Summary of botanical composition of 20 esophageal fistula collections from reindeer at Prudhoe Bay. (a) Percentage occurrence of plant groups and _ parts present in more than 1% of fistula samples. Cyperaceae 54.6 green (37.9) dead (16.7) Salicaceae 28.7 green (27.1) dead ( 1.6) Gramineae green 1.9 Herbs 733) Lichens 2p) Vascular bundles unidentified 45 Other dead unidentified 3.6 100.0 Cyperaceae constituted more than 50% of the diet, while Salicaceae composed almost 30%. Herbs formed only 7.5% of the diet, while the contribution of lichen and Gramineae was in- significant. Table 10(b) shows the frequency of occurrence of the main plant species. Analysis of esophageal egesta indicates that FE. angustifolium was the most frequently eaten plant during the summer season. (c) Botanical composition of caribou rumen samples. During the last week of July, four caribou rumen samples were collected for botan- ical analysis (Table 11). Almost 35% of the sample was Salicaceae; 28% Cyperaceae (identifi- able were 8% Eriophorum spp., 3% Carex aquatilis), and the balance was composed of herbs, lichen, and dead material. Approximately 14% of the sample was dead material. The nutritional history of the caribou was uncertain, but they were observed to graze mainly the Dupontia brook-meadow and, possibly, the sur- rounding Eriophorum marsh types preceding capture. From this standpoint, the analyses may be compared with esophageal egesta analyses obtained from reindeer grazing a Dupontia brook community at the same time. Comparison of values for the rumen samples in Appendix Table 5 with the values from the EF samples in Fig. 7 (Dupontia meadow) shows a_ greater amount of grass-like groups compared to willows in the EF samples, while the herb group is about equal. The caribou rumen samples show a higher (b) Percentage occurrence of plant species present in more than 1% of fistula samples. Eriophorum angustifolium 36.6 Salix ovalifolia 9.0 Carex scirpoidea 6.6 Salix arctica 5}5// Salix rotundifolia 3E5 Carex aquatilis $15) Dupontia fisheri 1.8 Dryas integrifolia 1.8 Thamnolia vermicularis 1.8 Carex rupestris lESeevaleo Trace and unidentified species 28.4 100.0 content of lichen than the EF samples. Detec- tion of quantitative differences in composition between the rumen and EF samples cannot be made due to the small sample sizes. Also, these differences in composition could be related to differential rates of ruminal turnover and/or digestion of the plant species. An absolute dif- ference in selective patterns of reindeer and caribou cannot be determined, although prefer- ence for Sa/ix spp. was apparently made by caribou. Plant biomass estimates in relation to vegetation type and grazing behavior Table 12 lists estimates of live, dead, and total biomass on five study sites at Prudhoe Bay. Peak biomass was recorded for each vegetation type in early to mid-July 1973. A marked decline in live biomass was noted in August. Insufficient sampling early in the season prevent- ed the construction of precise growth curves for these sites. However, based on previous studies of the seasonal progression of primary produc- tion at Barrow, Alaska, a linear growth is expect- ed from 20 June. Predicted seasonal patterns in primary production for the main vegetation types at Prudhoe Bay are shown in Fig. 9. Unfortunately, we were unable to estimate be- tween site variations in the seasonal primary production of any one vegetation type. Subjec- tive estimation suggests that variation within most vegetation types was high. For example, 168 Table 11 Botanical composition of rumen samples obtained by field rumenotomy on four caribou at Prudhoe Bay (July 1972). Vegetation Plant Number of samples Mean occurrence class species containing the species species class Salix arctica 2 23 S. lanata 1 3.0 S. reticulata 3 0.5 S. rotundifolia 1 0.3 S. pulchra 4 les) Miscellaneous * 2-3 16.7 Shrubs 4 34.3 Cyperaceae 4 16.6 Carex aquatilis 3 3e2 Eriophorum spp. 4 8.9 Dupontia fisheri 3 5.9 Equisetum spp. 3 11 Gramineae 3 2.8 Grass-like 38.5 Compositeae (flower heads) j 0.3 Polygonium viviparum 2 0.6 Valeriana capitata 1 tr Saxifraga spp. 1 tr Ste/laria spp. 1 tr Miscellaneous’ 2-3 8.9 Herbs 9.8 Cetraria spp. 2 1.4 Dactylina arctica 1 0.3 Sphaerophorus globosus 1 0.3 Thamnolia vermicularis 2 1.0 Lichen 3.0 Dead plant parts 14.4 14.4 Totals 100.0 100.0 “Partially digested plant parts; could not be identified into species. variation may be high within the Dryas heath/ snowbed community, depending on the relative contribution of the snowbed species to the communities. Also, variations in the amount of willows in the Dupontia wet meadow/brook bank community could result in variations in live biomass of between 30 and 90 g m?. Food intake of reindeer and caribou In principle, an estimate of daily food intake by adult caribou could be made by: (a) deter- mining the rate of eating (RI, g DM consumed per min eating time) of a tractable animal; and (b) relating RI to observations on the amount of time caribou spend eating. Thus, food intake (g d') = RI (g min'') x average daily eating time (min d'). (a) Estimation of eating rates. A quantita- tive estimate of food ingestion was made by assuming that all ingested food could be collect- ed from an esophageal fistula during a grazing period of fixed, or known, duration. A summary of rates of esophageal egesta collection rates for experiments in 1972 is shown in Table 13. A considerable variation in rate of intake was noted within vegetation types (coefficient of variation = 34-75%), and the variance (1.52 g min’') was high relative to the mean rate of 169 Table 12 Seasonal changes in biomass of some vegetation types at Prudhoe Bay (1973). Vegetation Number of Dry biomass (g/m?) type Date observations Live Dead Total Eriophorum angustifolium marsh 7/10/73 3 34.14 6.5 87.1422.1 121.2423 7/29/73 3 41.4+ 1.6 SMCEE hy) 75.3+ 7.4 8/12/73 2 18.14 4.4 66.2+ 7.0 84.34 8.9 9/19/73 3 Wea 228 111.1418.9 118.54+21.5 Dryas integrifolia heath/ 7/ 8/73 3 35.3+ 4.8 45.5+ 4.4 80.8+ 4.9 Salix rotundifolia snowbed 7/21/73 3 34.5+ 5.9 UBL 27. 110.8428.1 9/19/73 &) 21.9411.2 88.8+19.8 110.8+19.5 Dupontia fisheri brook meadow 7/19/73 3 Wier 87 76.7412.7 147.9+19.0 8/12/73 3 30.44 3.1 91.9+11.1 122.5+14.1 9/19/73 a TAL TA 837+ 7.9 91.8+ 9.1 Carex aquatilis marsh 7/20/73 3 25.94 3:2 55.2+12.6 81.4415.5 8/ 7/73 3 24.4+ 1.4 39.4+ 5.6 63.9+ 6.7 9/19/73 3 3.84 2.9 63.1436.4 66.9417.1 Sand dunes 7/14/73 2 31.4+ 7.6 20.5+12.1 51.907 4.5 Es = Qa 2 6 3 € 2 Oo 2 e Jo 10 20 30 10 20 30 10 20 30 10 20 June July August September Fig. 9. Predicted changes in live biomass availability based on data for late July (Table 72) and primary production rates for Barrow, Alaska (Tieszen 1977). , values used to calculate eating rate (Fig. 10) and eating time (Fig. 11) for the estimation of daily food intake (Table 15). A, Eriophorum marsh; O, Dryas heath/Salix snowbed,; @, Dupontia brook bank; A, Carex marsh. food intake for all studies (2.92 g min''). From such a high degree of variance, it can be inferred that factors regulating food intake were not constant from one estimation to the next. Changes were made in the experimental procedure in the following (1973) field season to increase the precision with which food intake could be estimated and to investigate some factors regulating food intake. Reindeer were fasted for 3-4 hr before using them in an intake experiment, and the collection period was re- duced (e.g., from 20 min in 1972 to 10 min in 1973). Further, three to five collections were made on the one vegetation type, and a 20 min grazing period was allowed between collections. These experiments indicated that the rate of food intake declined at approximately 30% per hr during a grazing period. The peak rate of food intake increased in a curvilinear fashion with available live biomass, as shown in Figure 10a. Eating rate was apparently maximized at 6g (DM) min! [6/83 = 0.072 g min! kg (BW)"'] at and above a live biomass of 70 g (DM) m?. It can be calculated that a reindeer confined to a small area has the potential to denude a range of live biomass 70 g m~? at arate of 11.7 min m2. This calculation assumes a simplistic approach to feeding, for the amount of time spent searching is not considered; however, the powerful harvesting potential of caribou is obvious. At the Prudhoe Bay study site, peak live biomass was in the range of 30 to 70 g m2 depending on the harvest date and the vegetation type (Fig. 9). Thus, some of the variance associated with the 1972 estimates of feeding rate (Table 13) could be attributed to variations in available biomass at the study sites. (b) Calculation of food intake from eating rates and time spent eating. During all periods free of insect harassment, adult caribou spent 51% of the day eating (Table 2), and the female- yearling-calf group spent 53% of the day eating. 170 Table 13 Mean rates of forage collection from esophageal fistulated reindeer. A collection period was started when the reindeer terminated its lying period; esophageal samples were collected over a timed interval of 14-20 min. Mean (+SE) rate of Vegetation Sample Number of dry matter collection CV type identification observations (g/min) (%) Eriophorum polygon marsh 1-7 7 2.54+0.35 36 Dryas heath and snowbeds 9-12 4 3.24 + 0.94 58 Dupontia brook/meadow 14-17 4 2.36 + 0.40 34 Carex marsh Sas 2 2737 + Ae26 75 Sand dunes (Salix ovalifolia) 19, 20 2 5.30+1.76 47 Total 1-7, 9-20 19 2'92:+0)35 52 CV = coefficient of variation (SDx100/mean). Fig. 10. Relationship between rate of eating, as estimated by collection of esophageal egesta, and available live biomass (a). Forage samples were collected over a 10 min period following 3-4 hr fasting. Theoretical relationships between percentage of day spent eating and availability of live biomass (b). The general relationship was adapted from data for grazing sheep (---, Young and Corbett, 1972). YZZZ,, average available live biomass at Prudhoe Bay in July (see Fig. 9). Esophageal Egesta Collection g DM (100 kg BW)! min"! O 20 40 60 80 Live Biomass (g DM m2 ; 2 ) Unfortunately, we have no comparable detailed estimates for adult males. However, we have estimates of the grazing intensities of these cohorts (Table 14) which show that lactating caribou graze more intensively than non-lactat- ing female caribou and caribou bulls. If it ts assumed that all cohorts spend the same propor- tion of the day grazing (where grazing time = eating time + searching time), then estimates can be made of the relative amount of time spent eating (Table 14). This may be an oversimplifica- tion of grazing behavior under natural condi- tions, for it is known that the amount of time ruminants spend grazing decreases exponentially with increasing available biomass (Young and f) 20 40 60 80 100 Corbett 1972). Since we were unable to deter- Live Biomass (g DM m2) mine this parameter, the general form of a relationship between grazing time and biomass Percentage of Day Spent Eating 171 Table 14 Comparison of grazing intensity (tSE) and the predicted time spent eating by unharassed caribou groups and reindeer. Number of Group observation Caribou males 22 Caribou, lactating females 22 Caribou, nonlactating females 4 and yearlings Caribou, calves (3-4 wk of age) = Esophageal fistulated reindeer, 19 nonlactating females Predicted daily Grazing intensity eating intensity (%) (%) (min) 60.4+4.3 46(40-50) 662 79.5+2.3 57(53-60) 821 67.5+6.0 49(45-53) 706 — 24 346 68.2+3.9 = = Grazing intensity = (eating time/eating time + searching time) x 100. Values in parentheses are the likely range for testing this model. *Based on an observed value of 52.8% for the eating intensity of females (Table 2) and the assumption that all cohorts spend approximately 66-67% of the day grazing (see text). availability was taken from previous studies on sheep (Allden and Whittaker 1970; Young and Corbett 1972) and adapted to the Prudhoe Bay site (Fig. 10b). It was assumed that (a) a mean live biomass of 45 g m? was available to the caribou in June, and (b) the relationship be- tween percent of day spent eating and live biomass was similar for the three cohorts. Thus, three parallel lines were available for the calcula- tion of the percent of day spent eating as the live biomass altered seasonally (Fig. 10b). The simplistic expression for calculation of food intake is given as food intake = eating rate x eating time. From the above discussion, it is clear that both factors on the right side of the expression are proportional to available biomass, and the rela- tionship between daily food intake as a function of live plant biomass is shown in Fig. 11. In the present study, the mean seasonal change in biomass was estimated from the trends in Fig. 9 in five 10-day intervals commencing 20 June. At the extremes during late June to early July, the main vegetation type consumed was the Dryas heath/snowbed type of biomass 25 g m~ (Fig. 9), while in late July to early August the Dupontia brook bank community of biomass 35 to 50 g m-2 was preferred. In the main, caribou were assumed to graze the Eriophorum marsh, with a live biomass in the range 25-45 g m2. = 200 ™ 2 | © 150 eae © aul = oo A AA —A—4—A 2 S ees °3 = [oe y, x oa s VA & ° S250 je) 9 Ww ANS B Q ) 20 40 60 80 100 Live Biomass (g DM m-2) Fig. 11. Theoretical relationships between daily food intake and availability of live biomass for lactating females (1), adult males (2), and non- lactating females (3). The relationships were calculated as the product of relationships shown in Figs. 10a and 10b. Summaries of expected biomass of live mate- rial, predicted mean daily food intake, and energy intake are shown in Table 15. For pur- poses of calculation, body weights of the adult cohorts—males, non-lactating females, and lactating females—were assumed to be respec- tively 115, 83, and 83 kg. 172 Table 15 Dry matter intake and energy available for fattening of caribou predicted from estimates of available live biomass and relationships between daily intake versus biomass (Fig. 11). Lactating females Cohort (83 kg BW) Period 1 2 3 4 Available live biomass (g m) 35 43 52 50 Drv matter intake (85% of peak, Fig. 11) (kg d7!) 2.90 3.35 3.10 3.55 tg d-! (kg9:75)-1] 105 122 131 129 Gross energy intake, GE| [kcal d”'(kg 0.75)" 514 598 642 633 Metabolizable energy intake, MEI (Mcal d!) ; 6.35 7.37 7.95 7.86 [kcald (kg 0.75) ] 231 268 289 286 Energy requirements, ER [kcal d™! (kg 0.75) '] maintenance 190 190 190 190 milk production 86 78 de 59 total 276 268 263 249 MEI/ER 0.84 1.00 1.10 1.15 Energy available for fattening (keal a7!) 715 1017 fikealidle” (kg O75) 1] 26 37 Body weight gain (gd!) Tie (kg 50d) ere Nonlactating female Males (83 kg BW) (115 kg BW) 5 1 2 3 4 5 1 2 3 4 5 25 35 43 52 50: 30 85. 438 52 50.2 285 2.90 2.54 2.88 2.08 3.02 2.54 3.09 348 3.65 3.62 3.09 106) 92) 405 9112-110 92 88 99° 04 108s ae 514 451 516 550 541 451 429 483 508 504 429 6.35 5.55 641 682 6.71 555 6.78 766 8.04 7.97 6.78 231 202° 233 248. 244. 202 193 218 229 227, 198 190 190 190 190 190 190 190 190 190 190 190 54 244 0.95 1.06 1.23 1.30 1.28 1.06 1.02 1.15 1.21 1.20 1.02 330 1182 1595 1485 330 105 983 1370 1299 105 12 43 58 54 12 3 28 39 of 3 SO..128 lis 161 36 4 106 148 141 #11 — 5.34 — — 4.17 — Periods 1-5 were respectively 21-30 June 1, 1-10, 11-20, 21-31 July, 1-10 August. Metabolizable energy intake = dry matter intake x gross energy of food (4.9 kcal g!) x energy digestibility (0.55) x metabolizability of digested energy (0.82). Energy requirement for maintenance = 2 x fasting metabolic rate [97 kcal a! (kg 0.75)"1]; energy requirements of lactation = energy output in milk/efficiency of milk synthesis (0.74). Body weight gain = energy available for fattening x efficiency of fattening (0.39)/energy content of new tissue [3.6 kcal g (FW) ]. The calculations indicated that the duration of eating in lactating females (Fig. 10b) leads to intakes of 2.9 - 3.6 kg d!' (105-131 [gd°! (kg°:7°)-'], which were as high or higher than intakes estimated for bulls (3.1 - 3.6 kg d''). When expressed per unit metabolic body size [gd°'(kg°:7°)-'] food intakes for non-lactating females were similar to the bulls but consider- ably lower than estimates for the lactating fe- males. (c) Prediction of forage removed by the Prudhoe Bay caribou population. To estimate the amount of forage removed by the caribou population at Prudhoe Bay, the estimates of individual food intakes in Table 15 must be multiplied by the number of animals in the cohort. Also, an estimate must be made of the amount of forage eaten by the yearlings and calves in the population. In the absence of empirical data on the grazing intake of calves and yearlings, the following assumptions were made: (1) Food intake of calves was assumed to increase with age from 38 [g d'! (kg®:75)"'] at 3 wk to 88 [g d'! (kg?:7°)'] at 6 wk. These intakes were 30-70% of adult values. Body weight gain was set at approximately 400 g dit (calculated from data for reindeer calves). (2) Intake of yearlings was assumed to be 114 [g d! (kg®:75)°'], and body weight gain was set at 250gd"'. Calculations were made on the likely food intake for each cohort for each period based on the mean population size for that period (Fig. 2) and the mean herd proportions for 1972 and 1973 as shown in Table 1. Estimates of the cohort and herd dry matter intakes for 1972 and 1973 are shown in Fig. 12. Thus, in 1972 when the average population on the study area was 155 animals, an estimated 25,000 kg of dry matter was consumed during the study period (21 June to 10 August). In 1973, the population was considerably lower, averaging 55 animals, 400 200 2=-0-== Average Population (no. of animals) \ $ 800 600 400 Cumulative Harvest of Herbage (kg) Average Herbage Removal (kg ad!) 20 30 10 20 30 10 June July Aug Fig. 12. Predicted cumulative herbage consump- tion by caribou in the Prudhoe Bay study area in the summer of 1972 and 1973. ts and the amount of herbage consumed in the study period was approximately 5,400 kg. (d) Estimation of size of study area. The interpretation given to harvest values has more meaning to the ecosystem as a whole if intake or harvest is expressed per unit area and in relation to primary production. As stated in the methods section, caribou populations at Prudhoe Bay were usually assessed by visual observation from the road system. The area under surveillance, 1.5 km on either side of the road, amounted to 530 km? and lay between the approximate boundaries of 149°05’ W in the east, 148°08’ W in the west, 70°08’ N in the south, and 70°22’ N in the north (Fig. 1). However, this area included riverbeds, ponds, and lakes as well as vegetated land. To estimate the relative amounts of each land type in the study area, 13 transects (6 north-south and 7 east-west) were drawn ona topographic map, and the relative occurrence of each area noted. The results, shown in Table 16, indicate that approximately 54% of the study area (i.e., 288 square km), was vegetated in late July and hence was available for grazing by caribou. An effort was also made to calculate the total area of continuous habitat available to the caribou at Prudhoe Bay. An examination of topographic maps of the Prudhoe Bay/Beechey Point area suggested that the coastal tundra was bounded by the Kuparuk and Sagavanirktok rivers, on the W and E respectively, and by the White Hills (approximately 75 km away) and Table 16 Approximate size of study areas and land classification. Available River bed Total for grazing Lakes and dunes Proportional 0.54 0.23 0.22 distribution (4SE) +0.03 +0.03 40.04 Study site (km?) 532 288 124 119 (Prudhoe Bay) Kuparuk/Sagavanirktok 2842 1540 665 637 River drainages (km?) Proportional distribution of land type was determined as fractional occurrence of each on 13 line transects drawn on a topographical map. Study site includes all land visible 1.5 km either side of the Prudhoe Bay road system. River drainage is bounded by the White Hills and Franklin Bluffs to the SE and S. 174 Franklin Bluffs (approximately 53 km away) to the SE and S respectively (Fig. 1). This drainage area was approximately 2,842 square km (Table 16). Thus, the study area was approximately 18% of the total drainage. It was anticipated that counts for the study area might be extrap- olated to the drainage, and further, that on days of high insect harassment, the number of cari- bou observed moving to the coastal dunes should represent the total number in the drain- age. Hence, observations of 20, 50, and 100 animals in the study area should yield estimates of respectively 110, 280, and 560 animals in the entire drainage. These latter values are similar to the numbers of animals moving to the coastal dunes on some days in 1972 and 1973 (Fig. 2). However, the estimate is very low compared with two peak values of 1,500 and 1,200 ani- mals observed in 1972 (Fig. 2). (e) Estimation of caribou biomass and herb- age intake in relation to seasonal primary pro- duction. From the size of the study area and that portion containing grazeable herbage (Table 16), an estimate was made of caribou densities (Table 17). In 1972 a mean population of 155 animals was at a density of 3.4 km2 animal-!; the effective density was 1.9 km2 vegetated area animal-!. The following year (1973), total and effective stocking density were respectively 9.7 and 5.2 km2 animal-!. At a seasonal primary production of 50-70 g m-2 (mean 55 g m2), it can be calculated that during the respective summers of 1972 and 1973, approximately 0.16 and 0.03% of the aboveground vascular production was ingested. If the animals noted in 1972 and 1973 remained on the study site year-round, then approximately 1.1 and 0.2% of the respective seasonal vascular productions would be removed in the entire year. /n vitro digestibility of plant species consumed by caribou Table 18 shows a comparison of indices of dry matter digestibility of selected plant species collected 12-25 July, 1972 at Prudhoe Bay. For the micro-digestion /n vitro technique, rumen liquor was obtained by rumenotomy from tran- quilized caribou, from rumen fistulated reindeer grazing vegetation at Prudhoe Bay, and from reindeer given prepared forages. Table 17 Prediction of herbage intake by caribou in relation to seasonal primary production. Herbage intake was calculated over a period of 52 days (21 June through 10 August). Parameter 1972 1973 Study area (km?) a) total 532 532 b) vegetated 288 288 Population size (average July/August) 155 55 Caribou density (No. km*2) a) total 0.29 (3.4) 0.10 (9.7) b) vegetated 0.54 (1.9) 0.19 (5.2) Seasonal primary production ~ Prudhoe Bay (kg km’) 55,000 55,000 (range 50-70 g m2) Herbage intake (50 d study period) a) total (kg) 25,000 5,400 b) per unit area (kg km?) 87 19 c) percentage of above-ground production 0.16 0.03 Value in parenthesis is caribou density expressed as km? caribou’!. “Calculated as peak above-ground, vascular live material. Table 18 Estimates of dry matter digestibility (%+SE) of hand-picked plant samples and esophageal egesta from reindeer. Rumen innoculum for the /n vitro technique was obtained from tranquilized caribou, reindeer grazing at the study site! or reindeer given a mixed diet. Plant sample Shrubs Salix arctica S. pulchra S. reticulata S. ovalifolia S. lanata Dryas integrifolia D. octopetala Sedge and cotton grass Carex aquatilis Eriophorum angustifolium E. vaginatum Grasses Dupontia fisheri Arctophila fulva Herbs Oxytropis sp. Braya spp. Parrya nudicalus Artemisia richardsoiana sp. Pedicularis sp. Saxifraga oppositifolia Lichens Cetraria cucullata C, islandica* Thamnolia vermicularis * Alectoria nigricans * Lobaria linita* Peltigera aphthosa* Stereocaulon alpinum * Cladonia alpestris C. uncialis* C. arbuscula* C. rangiferina* Mosses Hylocomium splendens* Sphagnum magellanicum * Other Esophageal egesta Eriophorum meadow Eriophorum meadow Dryas heath Dupontia brook bank combined /n vitro digestibility technique Source of innoculum Caribou Reindeer! Mean. Reindeer Roe SR Ea ROR Ss Ee Ee A a Ee Ras NS EE RSs Moss es RO Ni Es Set Se CO Eee ioe! pees ee ee Se ee eee as oe ee RESO DEES : RE Coes leaves CS RZ GRE SPS EE EOC COGREC RO RE ES ER Sa Re Ee CO RSS Ses CoS CS Seen EEE RO RE Oe Ce CO AIS ASN Ce a OO RO Ser RS ES EE ER oe Ee SSS CS CE HORSE ER Ls SE SEE SL CS MESES — SS Ae RE SOC GG DOGS CS EES EE SOR RR DE Es ESIGN ESS S222 RO SS A MET We Es Eee 1 Rumen fistulated reindeer were tethered on vegetation types at Prudhoe Bay. 2Rumen fistulated reindeer given a diet containing 67% (dry weight) lichens, 8% Carex aquatilis and 25% brome hay. The food was ground in a hammer-mill and thoroughly mixed. *Samples obtained from Coal Creek and Nome, Alaska 175 176 As a group, the grasses Dupontia fisheri and Arctophila fulva were more highly _ digest- ible than the herbs, sedges, or shrubs (Table 18). With one exception, all herb samples proved highly digestible (64-70%), as were the sedges and cotton grass (48-68%). Digestibilities of salices were generally lower at 34-54%; however, a singularly high value of 71% was noted for Salix arctica when incubated with rumen liquor from caribou. Dryas integrifolia was of even lower digestibility (12-33%) than the willows. Unfortunately, no mosses and only two lichens, Cetraria cucul/lata and Cladonia alpestris, were available for estimation of digestibility using inocula from caribou or reindeer at Prud- hoe Bay. Both lichen samples were obtained from Coal Creek, Alaska. C. cucu//ata was highly digested (48-74%), whereas the digestibility of C. alpestris was low (16-27%). A more complete study using inoculum from reindeer given a prepared forage high in lichen showed that the digestibility of lichens was highly variable (10-77%) depending on the species. In contrast, the digestibility of three mosses was very low (6-19%) (Table 18). Estimates of jn vitro digestibility of forage samples obtained from esophageal fistulated reindeer were moderate to high at 45 to 62%. However, estimates using liquor obtained from caribou were lower at 37 to 43% (Table 18). The mean estimate of digestibility of the initial four esophageal egesta samples, 52 + 3%, was higher than the estimate for a combined sample (45%), using liquor obtained from reindeer given a diet high in lichen. In view of the wide range in digestibility of the vascular plant species and groups, it is difficult to predict a biologically meaningful average digestibility based on botanical composi- tion, without incorporating the relative amounts of each plant species available or eaten. From the mean botanical composition for 20 esophageal fistula samples, shown in Table 10(b), and estimates of digestibility of the species (Table 18), a mean digestibility was calculated which was weighted for the relative abundance of each species (Table 19). For the esophageal samples, a mean digestibility of 56% was obtained; this estimate was 4% higher than the mean jn vitro digestibility (52%) of four esophageal samples shown in Table 18, and is considerably higher than those estimated using inoculum from caribou rumen (37-43%). A similar calculation based on the botanical analy- sis of rumen contents from caribou (Table 11) indicated a dry matter digestibility of 52% for forage consumed by them. Table 19 Comparison of jn vitro digestibility of esophageal egesta samples with dry matter digestibility calculated from the summation of individual estimates of digestibilities (Table 15) and the % occurrence of species in the vegetation types. Predicted dry digestibility based on botanical composition of: (a) range: (b) esophageal /n vitro digestibility Type live material total egesta of esophageal egesta Salix ovalifolia 15-17 47 — 44 ~ sand dunes Dryas integrifolia heath 2,9 44 41 50 49 Salix integrifolia snowbed 53 50 Dupontia fisheri 12 59 49 58 50 brook meadow Eriophorum 3-4 50 38 43 49-62 angustifolium marsh Carex aquatilis 5 62 51 56 51 marsh 177 Table 20 Chemical composition of plant material collected at Prudhoe Bay, 12-25 June 1972. Components were analyzed according to the detergent technique of Goering and Van Soest (1970). Values are expressed as g (100 g)! dry matter. In vitro ADF CC wc dry matter ligno-cellulose cell Hemi- digestibility Sample NDF or crude fiber contents cellulose Cellulose Lignin (%) Shrubs Salix arctica S. pulchra S. ovalifolia S. lanata Dryas integrifolia leaves/stem base inflorescences — Sedges Carex aquatilis Eriophorum angustifolium live leaves/10% dead inflorescence + stem Grasses Dupontia fisheri live leaves/10% inflorescences inflorescences + stem Arctophila fulva Herbs Artemisia richardsonii sp. Pedicularis sp. Saxifraga oppositifolia Lichens Cetraria cucullata Cladonia alpestris (Coal Creek) C. alpestris (Nome) Esophageal fistula egesta Mixed samples EF C1 C2 3} C4 Artificial food Mixed reindeer hay * Purina cattle starter No. 1 NDF, neutral detergent fiber; ADF, acid detergent fiber; CC, cell contents; CWC, cell wall constituents; lignin was determined as the mineral acid resistant component of ADF. /n vitro digestibilities were taken from Table 16. *78% lichen, balance of Carex aquatilis and brome hay. Cell Constituents = 100 — NDF ; Hemicellulose = NDF — ADF Cellulose = ADF — lignin 178 In an analagous manner to that used to estimate digestibility of esophageal and rumen samples, average digestibilities were estimated for each of the vegetation types at Prudhoe Bay (Appendix Tables 5-10). These estimates, shown in Table 19, are the predicted digestibilities if caribou were to graze these communities, con- suming the various vascular plant species in proportion to their availability. The estimates refer only to the time period 6-25 July. If caribou were to eat mainly the live plant mate- rial, the average digestibilities would be in the range of 44-62%, with the higher values noted for the wetter communities (the Dupontia fisheri brook bank/meadow and the Carex aquatilis marsh). The wetter communities also contain a substantially higher proportion of dead plant material. I!f such material is assumed to be 25% digestible, then the average digest- ibility for the community as a whole is reduced substantially (e.g., the Eriophorum angustifoli- um marsh, from 50 to 38%, and the Carex aquatilis marsh, from 62 to 51%) (Table 19). Also shown in Table 19 are the average /n vitro digestibilities of esophageal egesta collected from reindeer grazed on these communities, plus estimates of the digestibilities of the esophageal samples based on their botanical composition. In the drier habitats, it was apparent that digest- ibilities of selected material approximated that which was available as live material. However, in two of the wetter habitats, Dupontia fisheri brook meadow and Carex aquatilis marsh, the selected material was of a digestibility similar to that of the habitat as a whole (i.e., live + dead material). The suggestion that reindeer were consuming a significant proportion of dead plant material is not substantiated by the botanical analysis of the esophageal fistula samples, which indicated a low intake of dead plant material and litter (Fig. 7). We conclude that the /n vitro digestibility estimates for these communities (D. fisheri brook meadow, C. aquatilis marsh), may be underestimated. No evidence was found for selection of highly digestible material from within the com- munity. However, the pattern of selection of vegetation types described in Table 9 suggests some selection for digestibility, based on prefer- ence for the D. fisheri brook meadow vegeta- tion type. The lack of preference for the C. aquatilis marsh (Table 9), despite its predicted high quality (Table 19), suggests that its prefer- ability may have been lowered by other factors, such as water ponding in early July, being a prime mosquito habitat, and containing a high proportion of dead plant material. Chemical composition of plant material To date, a limited number of analyses have been made on plant samples collected at Prud- hoe Bay (Table 20), plus samples of lichen and moss collected at Nome and Cantwell, Alaska. These same samples were used in the /n vitro digestion studies (Table 18). Analyses have been confined to the determination of acid detergent fiber (ADF) and neutral detergent fiber (NDF), further subdivided into hemicellulose, cellulose, and lignin. Future determinations will be made of energy, total N, P, Ca, and K. The amount of cell contents in shrubs and herbs was high relative to hemicellulose. In grasses and sedges these components were simi- lar, and in some lichens the hemicellulose com- ponent was high relative to cell contents. The cellulose and lignin components of all vascular plants were variable. Lichens were virtually free of cellulose, although they contained a small amount [3.4 g (100 g)'] of acid resistant material which was allotted to the lignin compo- nent pending identification (Table 20). Table 20 indicates that ADF is quite variable in the vascular plants, but tended to be higher in the less digestible species. Lichens are generally thought to be high in crude fiber; the present analyses indicate that the ADF is low, and that the bulk of the cell wall constituents of lichen is a material which is extracted by neutral deter- gent in a manner similar to hemicellulose. The prepared diets given the reindeer were either based on lichen or were of a medium to high crude fiber commercial pellet. The former food contained 78% lichen, and the high content of hemicellulose reflects this component in the ration. Relationships between chemical composition and jn vitro digestibility of vascular plants. As stated above, it was apparent that /n vitro digestibility was high for plants of low crude fiber (ligno-cellulose) content. A significant rela- tionship between /n vitro digestibility (D, %) and the acid detergent fiber, or crude fiber, content [F, g (100g)'] was noted for higher plants (eq. D = 95 — 1.6 F SSS [3] A relationship of higher predictive value was noted between jn vitro digestibility (D, %) and lignin content [L, g (100g)']. The data are shown in Fig. 13; a double exponential line (eq. 4) was fitted to the data, wz. D = 32 @ 9-315 jE + 68e -0.0433 L [4] Thus, for plants containing less than 4% lignin, digestibility declined with lignin content at a substantially faster rate than plants contain- ing more than 6-8% lignin. Only one higher plant sample did not fit this relationship; the predict- ed jn vitro digestibility of the sample of Sa/ix lanata (61%) was almost twice the observed value (34%). No explanation can be given for this apparently aberrant result. However, this observation may be significant since S. /anata was seldom more than a trace constituent of esophageal egesta and rumen contents. There are many previous studies in domestic sheep and cattle which show that the apparent dry matter digestibility of herbage depends on its degree of lignification. In wildlife studies, browse material consumed by herbivores is fre- quently high in chemicals (e.g., tannins) which limit digestibility (Longhurst et al. 1968). Thus, the general relationship between digestibility and lignification is not as common for browsers as for the temperate grassland grazers. Present evidence suggests that digestive processes of caribou in the tundra ecosystem at Prudhoe Bay may function under principles similar to those noted for ruminants in temperate grassland graz- ing systems. Energy balance and energy flow through the Prudhoe Bay caribou population (a) Energy content of forage and intake by caribou. From estimates of the energy content of forages, dry matter intake (Table 15), and dry matter digestibility (Table 18, 19), the amount of energy harvested by caribou at Prudhoe Bay can be calculated. Individual estimates of the energy content of sedges, grasses, and shrubs at the study site have not been made. However, previous studies (West and Meng 1966) show that for the months June through August, gross 179 energy of most northern species which have been studied is between 4.83 and 5.02 kcal g'! dry matter. In the present calculations, a mean energy content of 4.9 kcal g' was assumed. It was also assumed that the metabolizable energy content of forage was 82% of digestible energy (Blaxter 1962). Table 21 shows a summary of assumed and calculated composition of late season (late July) forage at Prudhoe Bay. Values for the efficiency of utilization of net energy for milk synthesis and fattening were calculated from the predicted metabolizable energy content of the forage as proposed by Blaxter (1962). Table 21 Summary of estimated values for the nutrient status of herbage harvested by caribou at Prudhoe Bay. Dry matter digestibility = 53% Energy digestibility = 55% Gross energy content = 4.90 kcal g | Digestible energy content = 2.69 kcal g! Metabolizable energy content = 2.21 kcal g! Efficiency of utilization of net energy for (a) milk synthesis = 74% (b) body growth and fattening = 39% Table 15 lists a summary of expected intakes of gross and metabolizable energy by lactating females, non-lactating females, and adult males. It is clear that the intake of metabolizable energy per unit metabolic body size by the lactating females is considerably higher than in the other cohorts. Maximal intakes of gross and metabolizable energy were calculated for early to mid-July. (b) Maintenance energy requirement and energy expenditure of caribou. No estimates were available of the daily maintenance energy requirement of grazing caribou. However, from our modeling efforts below (see Modeling activ- ities associated with the study of caribou at Prudhoe Bay), we can predict a daily heat production of approximately 150 [kcal d"' (kg°-7°)"'] which is 1.55 times the fasting metabolic rate of caribou-97_ [kcal d-! (kg?:7®)'] (McEwan 1970). This estimate is low compared with the best empirical field estimates of the daily maintenance energy re- quirements (or heat production) of sheep at pasture, which are approximately 2.0 times the 180 fasting metabolic rate (Young and Corbett 1972). Therefore, we have assumed a value of 190 [kcal d!' (kg®-7°)'] (or 1.97 x fasting metabolism) for caribou. The maintenance energy requirement, or daily metabolic rate, of caribou would be higher under conditions of insect harassment; hence the following estimates should approach favorable grazing conditions. For lactating animals, the amount of energy secreted in milk and associated with milk syn- thesis (i.e., the efficiency of milk synthesis), was also estimated as a component of the main- tenance energy requirement of lactating females. Estimates of the amount of milk synthesized were taken from estimates for reindeer given by equation 1 (White, Holleman, and Luick, unpub. obs.), and an efficiency of 74% for synthesis was assumed (Blaxter 1962). The predicted main- tenance energy requirements as shown in Table 5: (c) Net energy and predicted body-weight gain. The amount of energy available for synthe- sis of body tissue (i.e., net energy) was estimated as follows: Net energy = Metabolizable energy intake— Maintenance energy requirement——————— [5] Calculations from the present data suggest that lactating females were in positive energy balance for only periods 3 and 4 (11-31 June, approxi- mately). For the non-lactating female and adult male segments of the population, a positive energy balance was noted for periods 1-5 (i.e., for the entire 50 days). If it is assumed that net energy is used in the proportion of 80% for fattening and 20% for growth, then tissue would be synthesized at between 77 and 173 g d'', which amounts to cumulative body weight gains of 1.9, 5.3, and 4.2 kg for the lactating female, non-lactating female, and the male segments, respectively. It was found in this study that the digestibil- ity of the diet was an important determinant of the amount of food retained for fattening. For example, in the non-lactating female cohort, if the digestibility of the diet is increased by 10 units from 55 to 65% (i.e., by 18%), the amount of energy retained daily for fattening increased from 467 to 1,402 kcal (i.e., by 200%). This effect has previously been reported for domestic animals (Blaxter 1962); the powerful multiplier effect highlights the requirement for an accu- rately determined forage digestibility. Modeling activities associated with caribou studies at Prudhoe Bay It is clear from estimates of food intake, energy balance, and energy flow that many variables influence the final results..In the above calculations, it was necessary to assume values for variables (e.g., time spent grazing, eating rate, digestibility, caribou biomass) based on limited empirical estimates. It was not possible within the constraints of time to investigate the sensitivity of the calculated end product (e.g., food intake and body growth) to small changes in the magnitude of these variables. To investi- gate these limitations, a modeling effort was initiated in January 1973. The objectives of the modeling activities were to: (a) determine the average daily metabolic rate, or heat production, of caribou cohorts based on (i) estimates of energy costs of activ- ities such as standing, walking, grazing, etc.; (ii) time budgets of these activities, and (iii) changes in behavioral activities in response to abiotic and biotic variables. This submodel was termed ACTIVE. (b) determine daily amounts of forage con- sumption and plant community/species selec- tion, apparent digestibility, and metabolizable energy intake based on (i) estimates of eating rate as a function of plant live biomass; (ii) eating time as a basis of rumen fill, (iii) daily food intake as a function of eating rate and eating time, (iv) plant selection based on a matrix of chemical composition and biomass of plant types, and (v) digestibility and metaboliz- ability of forage based on its chemical composi- tion (% lignin). This model was termed GRAZE, and (c) interface models ACTIVE and GRAZE to predict net energy available for growth and fattening of both adult and juvenile co- horts. Growth and fattening were calculated based on (i) estimates of daily net energy avail- able for growth and fattening (i.e., metaboliz- able energy intake — average daily metabolic rate = net energy), and (ii) efficiency of growth and fattening based on the metabolizability of forage and milk. This interface model was term- ed GROWTH. Models ACTIVE and GRAZE have been used in preliminary investigations (F. L. Bunnell, R. G. White, and D.E. Russell, unpub. obs.). From gaming runs with model ACTIVE, we predict that periods of severe insect harassment of more than 2 hr duration could increase the daily heat production by 1.6 to 3 times the average daily metabolic rate estimated for an insect-free day. It will be used in future studies to investigate harassment problems and, hope- fully, to predict energy costs of harassment by human, vehicle, and aircraft interference in theoretically ‘‘habituated” and ‘‘non-habituat- ed”’ caribou populations. Model GRAZE is being used to investigate the range of possibilities that exist for caribou to select vegetation types, plant groups, and plant species at Prudhoe Bay. For example, what would be the expected change in grazing pattern and food intake if caribou were selectively graz- ing plants high in protein, phosphorus, or energy rather than selecting those of highest digestibil- ity? Model GRAZE will also be useful in predict- ing the rate of diminution of plant biomass in the event of inadvertent or planned holding of caribou on the Prudhoe Bay development. Model GROWTH is still in the coding stage. As soon as it has been interfaced with models ACTIVE and GRAZE, an attempt will be made to set limits on the upper stocking capacity which will ensure, firstly, a sustained population and, secondly, a sustained yield for this area. Discussion This project did not aim at determining the year-round population dynamics and movement of caribou at Prudhoe Bay. Hence, the herd or herds (Arctic or Porcupine) to which these caribou belong in the study years remains un- known. Our own studies on behavioral patterns, combined with local observations on the pres- ence of animals on a year-round basis, indicate that there are two caribou populations at Prud- hoe Bay. One may be considered resident, the other migratory. The resident herd is probably small in number, perhaps 5-30 being visible from the road system during most seasons. They also appear to become habituated to traffic on the road system, unlike the migratory animals. Based on an extrapolation of 55 animals in the study area, it is suggested that the maximum 181 “resident’’ population may be 300 animals oc- cupying the draining basin of the Kuparuk and Sagavanirktok rivers and bordered on the south by the Franklin Bluffs and. the White Hills (Fig. 1). This is a total tundra area of approxi- mately 2,840 km? (Table 18). The approximate stocking rate would be 0.1 caribou km? (0.3 caribou mile?) or 10 km? (3.9 mile?) per cari- bou. This density is low compared with esti- mates of 1-3 caribou mile? for the Arctic, Porcupine, and Kaminuriak herds (Calef 1974), and must be considered a minimal estimate for it does not include the peak influx of migratory animals. The upper limit may be set by the availability of winter range because separate studies at Prudhoe Bay show that although there are a large number of lichen species, their actual distribution is limited to the dry habitats, and except for a peak biomass on one habitat of 88 g m2 the biomass is generally low (0-55 g m*) (Williams et al., this volume). Therefore, resident caribou would have to supplement their winter diet with sedges, grasses, herbs, and willows in the more exposed communities. Again, the biomass would be small; plant material of high digestibility may be available at only 7-20 g m°. Dead material of much lower nutrient status would be present at 60-110 g m? (Table 12). A possible alternative source of winter range may be available on the Franklin Bluffs and in the White Hills. In previous years large groups of caribou have been observed overwintering in the central arctic region (Collins 1937, cited by Skoog 1968: Olsen 1959, cited by Child 1973), and the same region is a calving area (Skoog 1968; Child 1973). Hence, in some years the “‘resident’”’ population of caribou may be up to 10 times the assumed number (ca. 300) in this study. In summer 1972 an average of 155 caribou were noted in the study area, and by extrapola- tion to the entire river drainage system, it was suggested that ca. 900 used the coastal plain at Prudhoe Bay. This number is only one-third of the peak numbers (ca. 3,000) reported by Child (1973). However, these latter reports were for animals moving through the area under insect harassment and presumably originating from outside the Kuparuk/Sagavanirktok drainage area. While it is not appropriate to base foraging and energy flow calculations on this peak num- ber of animals, it may be appropriate to extrap- 182 olate to peak numbers in the 1972 and 1973 season to allow an assessment of the impact of the periodic high population numbers referred to by Skoog (1968). Without estimates of calf, yearling, and adult rates of mortality, it is difficult to make a precise estimate of the productivity of a caribou herd. From acalf composition of 16% in August (Table 1), it can be argued that herd recruitment would be sufficient to meet losses; hence, a population increase would be expected. For Newfoundland caribou, Bergerud (1971) showed that a calf composition of 15% of the popula- tion in October could lead to a significant annual rate of increase. The traditional migratory patterns of cari- bou of the Arctic and Porcupine herds have been described by Lent (1966) and Hemming (1971). More specific movement and migratory patterns of caribou in the central North Slope have been described by Child (1973) and Gavin (1975). Briefly, the animals move into the arctic tundra down the Colville and Canning rivers and spread out to enter the Prudhoe Bay area down the Kuparuk and Putuligayuk rivers in the south and southwest and across the Sagavanirktok delta in the east. Child (1973) generalizes this movement pattern as being from east to west in the 1971 and 1972 field seasons. However, superimposed on these general movement trends are the insect- evoked movement patterns, which result in cari- bou moving to the coast and occasionally to an inland relief area, followed by a slow dispersal inland once insect attack declines. During the rapid insect-evoked movements (Fig. 2), use is made of the numerous game trail systems (see Child 1973, Figs. 2a, 2b). On the other hand, during slow dispersal and grazing, caribou sel- dom use the trails. Trails intersect many of the roads at Prudhoe Bay, which necessitates several crossing points. Caribou readily crossed the roads and, in some cases, used them as insect- relief areas. The interaction of caribou with other man-made obstacles has been studied in- dependently (Child 1973). Observations on grazing behavior of caribou undisturbed by insects were confounded by group size and composition. In the smaller groups a general preference for vegetation in the drier habitats was noted. Groups comprising approximately 50 or more caribou showed no preference for vegetation type. This may have been due to the requirement for a certain mini- mum distance between individuals of the group. In this respect, it was observed that within groups of males, individuals were apparently more tolerant of each other than was the case in groups of lactating females and their calves. No unequivocal evidence could be gained for com- munity selection because of the relatively small size of stands of vegetation of the various types and, except for the Dupontia brook/meadow type, because of lack of continuity between stands. However, the data in Table 9 indicate some preference for the Dryas heath/Sa/ix rotundifolia snowbed and Dupontia brook mea- dow communities. Also, there was an apparent lack of preference shown for the Carex aquatilis marsh, which could be attributed to its being a prime mosquito habitat. In spite of apparent preferences for certain communities, their low availability resulted in the occurrence of grazing (42%) in the Erfophorum polygon marsh communities. Within the plant communities, some prefer- ence was shown by esophageal fistulated rein- deer for grasses and sedges (Fig. 7). Exceptions to this generalization were noted for the Dupontia brook meadow and Salix ovalifolia sand dunes, where preferences were also noted for willows. Thus, in summarizing the analyses of 20 esophageal fistula samples, it was found that Eriophorum spp and the salices made up respec- tively 37 and 29% of the diet (Table 10). Analyses of four caribou rumen samples yielded similar results, with grasses and sedges constitut- ing 38% of the diet and salices 34% (Table 11). Eriophorum spp. constituted a lower proportion of the diet of caribou than of reindeer (Tables 10 and 11). Preference for the Dryas heath and Salix rotundifolia snowbed communities was probably a reflection of their higher availability and more advanced phenology compared with other com- munities early in the season (late June-10 July). At this time the live biomass was relatively high (35 g m2), and dead material low (Table 12). However, the predicted, average apparent dry matter digestibility was relatively low (44-53%, Table 19). In early July the Dupontia brook rneadow contains considerably more live plant material (71 g m*) than other communities (26-41 g m?) (Table 12), and the predicted apparent dry matter digestibility of the live biomass was high at 59% (Table 19). This com- munity also contains considerable amounts of D. fisheri, a grass which, until flowering, is poten- tially highly digestible (ca. 79%, Table 18), plus a wide range of willows and herbs which provide considerable variation in the diet. In comparison with the Dupontia brook meadow, the most used community, the Eriophorum polygon marsh, was of only moder- ate nutritive value. The live biomass was moder- ate (34-41 g m?), which might limit eating rate and cause some compensatory increase in graz- ing time (Figs. 10a, 10b, 11), and the average digestibility of live material of the community was only 50% (Table 19). Selection within the community could lead to a higher digestibility of forage, but this must be balanced against increased searching time. The apparent lack of preference for the Carex aquatilis marsh may be attributable to several factors: It is a prime mosquito habitat, is unavailable due to high water levels in early summer, is of low live biomass (24-26 g a), and is relatively high in dead material (Table 12). In compensation, the predicted apparent dry matter digestibility of the live plant material was over 60% (Table 19). Thus, when mosquitos are not a problem, this community is potentially useful for grazing by caribou in late July and August. Care should be taken in translating informa- tion based on the original vegetation analysis to the more detailed vegetation analysis of Webber and Walker. In Fig. 7 a comparison is shown between our present scheme and the more detailed scheme outline by Webber and Walker. In general, good agreement was noted between the schemes. However, because the cryptogams were not used in defining the vegetation and because Carex aquatilis, Eriophorum angusti- folium, and Dupontia fisheri are found in most vegetation types (Appendix Table 10), some inconsistencies may arise in defining the Carex aquatilis and Eriophorum angustifolium marshes. The key used by Webber and Walker is shown in Fig. 7, and it is clear that, initially, the absence or presence of moss and, finally, the type of moss dictates the allocation of vegeta- 183 tion to types 4, 5, and 6. These vegetation types were placed in the Carex marsh type in Skog- land’s scheme. A summary of the above characteristics of each community is shown in Fig. 14. Future gaming runs with model GRAZE may help to show the relative importance of each factor in affecting food intake by caribou. The present results are limited to the observation that above maintenance, an 18% increase in apparent dry matter digestibility can lead to a 200% increase in energy retention. The relative importance of small changes in other factors (e.g., community availability, live biomass, or the ratio of live/ dead biomass) are not known. It can also be shown that caribou have the potential to denude the range of live biomass at a rate of 11 min m°?. Thus, any inadvertent restriction of animals onto a small area could result in rapid removal of live plant material. Effects of trampling may also be important in destroying the habitat. From the observed available live biomass (Table 12) and relationships between eating rate and biomass (Figs. 9 and 10), it is clear that available biomass limits forage intake on most plant communities. However, when not harassed by insects, caribou can apparently graze for extended periods of time. They spend up to 53% of the day eating, which is equivalent to a grazing period (eating plus walking) of 60-65% of the day (Tables 2a, 2b). Predictions based on grazing behavior (Tables 2 and 14) indicate that by virtue of their higher rates of grazing inten- sity, lactating females have a higher rate of ingestion of food than non-lactating females and males. Although this observation agrees with field studies on domestic sheep (Arnold and Dudzinski 1967), future work is required to verify this critical point in reindeer. Esophageal collections using lactating females should be compared with those for adult males and the current estimates of eating rate of non-lactating females. This type of experiment should be extended to weaned calves and yearlings, as we currently have no estimates on the relative eat- ing activities of these cohorts. Similarly, more information is required on the interaction of grazing and eating times with available biomass and canopy structure (Fig. 10). More informa- tion on these factors will allow refinement on the current estimates of food intake. 184 (D, %) 20 D=32¢e0-3!15L , 68e ~0:0433L O OD Rae Si le aGrZOm2428 <| Lignin Content [L.g (100g) !] vitro Dry Matter Digestibility Fig. 13. Correlation of in vitro digestibility with lignin content of vascular plants. @, shrubs; O, sedges; @, grasses; 0), herbs; A , commercial pellets. Biomass estimates for July, August, and September (Table 12) are in general agreement with previous intensive studies at Barrow, Alaska (Tieszen 1972). Peak live biomass is noted in the last week of July, and biomass declines marked- ly in most communities after this date. Chemical analyses are not complete; hence, no trend with age in the degree of lignification can be shown. However, preliminary evidence, again at Barrow, indicates an increase in lignin and a decrease in soluble (cell constituents) components of the plant during August (B. H. McCown, L. L. Ties- zen, and P. W. Flanagan, pers. comm.). At the start of the growing season, the effective produc- tivity of herbivores is limited by the available biomass and the rate of biomass increase. At the end of the season (early to mid-August), produc- tivity is also limited by the nutrient content of the available herbage. The amount of energy which is harvested by caribou and which becomes available for produc- tion depends on the maintenance energy require- ment of the animal. In turn, maintenance energy requirement is highly dependent on the activity pattern of the grazing animal. Insect harassment can increase substantially the daily heat production, the amount of the latter de- pending on the duration and intensity of harass- ment, the speed of movement, and the distance moved by the caribou. Following the present study, we are using simulation modeling (model ACTIVE) to give estimates of energy costs of insect harassment. Until this study is complete, we cannot calculate the loss in production (i.e., in potential milk production, growth, and fat- tening), which could be attributed to insect harassment in the 1972 and 1973 field seasons. Growth and fattening can only occur once the maintenance energy requirements have been reached. We have calculated that for mature caribou, net energy of growth and fattening may be available for only a limited time period, i.e., the month of July (Table 15). During July weather conditions favor mild to severe insect harassment 20% of the time. Hence, the poten- tial productivity of a resident herd already sub- jected to a limited period of positive energy balance may be further limited by insect harass- ment. Also, during this period (July), the amount of energy diverted to growth and fatten- ing is highly dependent on the dry matter digestibility, or the metabolizable energy con- tent, of the forage. The mean metabolizable energy content of forage consumed by caribou was estimated at 2.2 kcal g! dry matter. This value compares with medium to good quality forage from other grassland systems. When avail- ability is not limited, this would support good animal productivity. It is clear from the present study that the Prudhoe Bay area is only moderately productive for caribou. Stability of the ecosystem is appar- ently achieved by low stocking densities, the latter resulting in consumption of less than 2% of the annual primary production (Table 17, Fig. 13). Thus, there is an adequate biomass “buffer’’ available to meet the infrequent and unpredictable entry of large caribou herds. The number of animals which apparently overwinter in the Prudhoe Bay area is small and is perhaps limited by nutritional as well as climatic factors. Adverse weather conditions plus lack of protec- tion from strong winds may place a severe limitation on the time available for winter graz- ing on the arctic coastal plain. This, combined with minimal lichen distribution and biomass (0-88 g m2), a low biomass of frozen forage of high digestibility, and possibly a snow cover of high hardness index, would suggest an area of poor winter habitat for caribou. When a poor winter habitat is combined with a limited period Vegetation Type (Webber's Classification) Relative Insect Relief 60; am Availability 4 (% of mt 0 In vitro 60 Digestibility aof al = (%) 20 Peak = — Biomass 60 (g m-2) 40 || 20 Biomass 1.5 ee Ratio fi a (Live/Dead) .5 49) Relative 12 77) Preference | | /// Index 4 ///\ (R) (0) = Increasing Wetness of Habitat [R=Availability x Digestibility* Biomass * (Live/Dead)] Fig. 14. Summary of relative characteristics of vegetation types which appear pertinent to cari- bou habitat at Prudhoe Bay. Relative degree of insect relief is a subjective assessment; avail- ability, see Table 8; in vitro digestibility, see Table 19; peak biomass, see Table 12 (live biomass); biomass ratio, calculated as ratio of live/dead, including litter at peak live biomass, see Table 12); relative preference index of herbage was calculated as the product of avail- ability of community type, in vitro digestibility, peak biomass and ratio of live/dead. when energy is available for growth and fatten- ing, low survival might be expected. Late July and August productivity would be higher if caribou followed the phenologic and primary production progression in vegetation types from south of the Prudhoe Bay study area into the foothills of the Brooks Range. This strategy might explain the adaptive significance of ob- served migration patterns of caribou, but why a small herd remains resident in the Prudhoe Bay area is less easily explained. 185 Acknowledgements This project was supported by Grant No. GB-29342 to the University of Alaska under the auspices of the U.S. Tundra Biome Program from the Office of Polar Programs and the International Biological Program of the National Science Foundation. Logistic support at Prud- hoe Bay was made available through the Tundra Biome Center, University of Alaska, from funds provided by the Prudhoe Bay Environmental Subcommittee; the Naval Arctic Research Laboratory, Barrow, Alaska, assisted in the transport of reindeer. Additional support was provided through contract with the U. S. Atom- ic Energy Commission (AEC _ Contract [(45-1)-2229-TA3] ). The authors are grateful to the late Scott Parrish for his assistance in logis- tics as site coordinator at Prudhoe Bay. The skilled technical assistance of A.M. Gau, P. Frelier, and Sandra White is gratefully acknowl- edged. R.G. White and J. R. Luick acknowledge international cooperation with the Grazing Pro- gramme of the Norwegian IBP Committee through exchange of data and personnel. The models ACTIVE and GRAZE were developed in cooperation with Dr. Fred Bunnell, Faculty of Forestry, University of British Columbia. References Allden, W. G. and I. A. McD. Whittaker (1970). The determination of herbage intake by grazing sheep: the interrelationship of fac- tors influencing herbage intake and availabil- ity. Aust. J. Agric. Res., 21:755-766. Arnold, G.W. and M.L. Dudzinski (1967). Studies on the diet of the grazing animals. Ill. The effect of pasture species and pasture structure on the herbage intake of sheep. Aust. J. Agric. Res., 18:657-666. Bergerud, A. T. (1971). The population dynam- ics of Newfoundland caribou. Wildlife Monog. No. 25, 55 pp. Blaxter, K. L. (1962). The energy metabolism of ruminants. C.C. Thomas, Springfield, III., 332 pp. Brody, S. (1964). Bioenergetics and growth. Hafner Pub. Co. Inc., N. Y., 1023 pp. 186 Calef, G. W. (1974). The predicted effect of the Canadian Arctic Gas Pipeline Project on the Porcupine caribou herd. Pages 101-120 jn Research Reports, Vol. 4. Environmental impact assessment of the portion of the MacKenzie gas pipeline from Alaska to Alberta. Environmental Protection Board, Winnipeg, Man., Canada. Calef, G.W. and G. M. Lortie (1973). Observa- tions of Porcupine caribou herd 1972. Sec. 1, Append. 1, Wildlife, to interim report No. 3: Toward an environmental impact assess- ment of a portion of the MacKenzie gas pipeline from Alaska to Alberta. Environ- ment Protection Board, Winnipeg, Man., Canada, 127 pp. Child, K.N. (1973). The reactions of barren ground caribou (Rang/fer tarandus granti) to simulated pipeline and pipeline crossing structures at Prudhoe Bay, Alaska. A com- pletion report of the Alaska Cooperative Wildlife Research Unit, 49 pp. . (1975). A specific problem: the re- action of reindeer and caribou to pipelines. Pages 14-19 /n Proc. 1st Int. Reindeer and Caribou Symp., Fairbanks, 9-11 August 1972, University of Alaska Biol. Papers, Special Report No. 1. Dahl, E. (1956). Rondane: Mountain vegetation in South Norway and its relation to the environment. Det Norske Vid. Akademi 1. Mat. Naturv. Klasse No. 3, 374 pp. Dieterich, R. A. (1975). Esophageal and ruminal fistulization of reindeer. Pages 523-527 jn Proc. 1st Int. Reindeer and Caribou Symp., Fairbanks, 9-11 August 1972, University of Alaska Biol. Papers, Special Report No. 1. Espmark, Y. (1971). Mother-young relationship and ontogeny of behaviour in reindeer (Rangifer tarandus L.) 2. Tierpsychol., 29:42-81. Gaare, E. (1968). A preliminary report on win- ter nutrition of wild reindeer in Southern Scandes Norway. Pages 109-115 jn 21st Symp. Zool. Soc. London (M. A. Crawford, ed). Gaare, E. and T. Skogland (1971). Villreinens naeringsvaner. Report from the grazing proj- ect of the Norwegian IBP committee. Statens viltundersokelser, Trondheim (En- glish summary), 25 pp. Gaare, E., T. Skogland, and B. R. Thomson (1970). Wild reindeer food habits and behavior, Hardangervidda, Jan.-July 1970. Report from the grazing project of the Nor- wegian IBP committee. Statens viltunder- sokelser, Trondheim (English summary), 97 pp. Galt,, H: D., PR. Ogden, |-/N: Ehrenreich i ib: Theuer, and C. S. Martin (1969). Estimating botanical composition of forage samples from. fistulated steers by a microscope method. J. Range Mgmt., 21:397-401. Gavin, A. (1975). Weather and its effect on caribou behavior patterns and migration. Pages 414-419 jn Proc. 1st Int. Reindeer and Caribou Symp., Fairbanks, 9-11 August 1972, University of Alaska Biol. Papers, Special Report No. 1. : Goering, H.K. and P.J. Van Soest (1970). Forage fiber analyses. Agr. Handbook No. 379, U.S. Govt. Printing Office, Washing- LOND! Gs, 20! pp: Grieg-Smith, P. (1964). Quantitative plant ecol- ogy, 2nd ed. Butterworths, London, 256 pp. Hanson, H.C. and E. D. Churchill (1961). The plant community. Reinhold Pub. Co., New York, 218 pp. Hemming, J. E. (1971). The distribution and movement patterns of caribou in Alaska. Alaska Dept. Fish and Game, Game Tech. Bull. No. 1., 60 pp. Hultén, E. (1968). Flora of Alaska and neighbor- ing territories. Stanford University Press, Stanford, Calif., 1008 pp. Leng, R. A. and G. J. Leonard. 1965. Measure- ment of the rates of production of acetic, propionic, and butyric acids in the rumen of sheep. Br. J. Nutr., 19:469-484. Lent, P. C. (1966). The caribou of northwestern Alaska. Pages 481-517 jn Environment of the Cape Thompson Region, Alaska (N. J. Wilimovsky and J.N. Wolfe, eds.). U.S. AEC Div. Tech. Inf. Ext., Oak Ridge, Tenn. Le Resche, R.E. (1975). The _ international herds: present knowledge of Steese-Forty- mile and Porcupine caribou herds. Pages 127-139 jin Proc. 1st Int. Reindeer and Car‘i- bou Symp., Fairbanks, 9-11 August 1972, University of Alaska Biol. Papers, Special Report No. 1. Longhurst, W. M., H. K. Oh, M. B. Jones, and R.E. Kepner (1968). A basis for the palat- ability of deer forage plants. Trans. N. Am. Wild/. Nat. Resour. Conf., 33:181-192. McEwan, E.H. (1970). Energy metabolism of barren ground caribou (Rang/fer tarandus). Can. J. Zool., 48:391-392. Pegau, R. E. and J. E. Hemming (1972). Caribou report, Vol. 12. Projects W-17-2 and 3. Alaska Dept. Fish and Game, Juneau. Skoog, R. D. (1968). Ecology of the reindeer (Rangifer tarandus granti) in Alaska. Ph.D. thesis. University of California, Berkeley, 699 pp. Thomson, B. R. (1971). Wild reindeer activity, Hardangervidda, July-Dec. 1970. Report from the grazing project of the Norwegian IBP committee. Statens viltundersokelser, Direktoratet for Jakt, Viltstell og Fersk- vannsfiske, Trondheim, 83 pp. (1973). Wild reindeer activity, Hard- angervidda, 1971. Report from the grazing project of the Norwegian IBP committee. Statens viltundersokelser, Direktoratet for Jakt, Viltstell og Ferskvannsfiske, Trond- heim, 76 pp. 187 Tieszen, L. L. (1972). The seasonal course of aboveground production and chlorophy!| distribution in a wet arctic tundra at Barrow, Alaska. Arct. Alp. Res., 4:307-324. Tilley, J.M. A. and R. A. Terry (1963). A two- stage technique for the /n vitro digestion of forage crops. J. Br. Grassland Soc., 18:104-111. Webber, P. J. and D. A. Walker (This volume). Vegetation and landscape analysis at Prud- hoe Bay, Alaska: A vegetation map of the Tundra Biome study area. West, G. C. and M. S. Meng (1966). Nutrition of willow ptarmigan in northern Alaska. Auk, 83:603-615. White, R. G. and R.A. Leng (1968). Carbon dioxide entry rate as an index of energy expenditure in lambs. Proc. Aust. Soc. Anim. Prod., 7:335-341. Williams, M. E., E. D. Rudolph, and E. A. Scho- field (This volume). Selected data on lichens, mosses, and vascular plants on the Prudhoe Bay tundra. Young, B. A. and J. L. Corbett (1972). Mainte- nance energy requirement of grazing sheep in relation to herbage availability. 1. Calo- rimetric estimates. Aust. J. Agric. Res., 23:57-76. 188 Appendix Table 1 Botanical composition of esophagus fistula samples from Eriophorum angustifolium polygon marshes. Percent. 1 aes 4 Ere 5 ares ey wSos wes Gale’ Hees mae) oe Ee | aaa = 5 ol ~N Corresponding veg. plots 10-14 15-21 EF samples Shrubs Dryas integrifolia Salix arctica Salix ovalifolia Salix reticulata Salix spp. leaves Salix spp. flowers Salix spp. stems Grass-like Eriophorum angustifolium Eriophorum angustifolium culm Eriophorum angustifolium flower Equisetum variegatum Herbs Braya spp. herb spp. Lichens Cetraria islandica Dactylina arctica Nephroma arctica Thamnolia vermicularis Dead and Litter Eriophorum angustifolium Dryas integr‘folia Salix spp. Hair, Rangifer Plant epidermis Vasc. bundles Insect, Aedes spp. 189 Appendix Table 2 Botanical composition of esophagus fistula samples from Dryas-heath communities and Sa/ix rotundifolia snowbeds. Percent. Corresponding veg. plots 42.47 and 53-57 38-41 EF samples 8 9 10 11 UZ S3D: Shrubs < : 10.5 Dryas integrifolia flower Dryas integrifolia leaf Salix arctica Salix pulchra Salix reticulata Salix rotundifolia Salix spp. Salix spp. flower Salix spp. stem Vaccinium vitis-idaea Grass-like Alopecurus alpinus Carex membranacea Carex rupestris Carex scirpoidea Carex spp. Carex spp. flower/fruit Eriophorum angustifolium Equisetum variegatum Herbs Braya spp. Draba alpina Lagotis glauca Oxytropis spp. Parrya nudicaulis Herb Lichen Dactylina arctica Thamnolia vermicularis Dead and litter Eriophorum angustifolium Dryas integrifolia Carex spp. Salix spp. Litter unspecified Epidermis Vasc. bundles 190 Corresponding veg. plots EF samples Shrubs Dryas integrifolia Salix arctica Salix lanata Salix reticulata Salix rotundifolia Salix spp. Salix spp. stem Grass-like Carex aquatilis Carex culm Dupontia fisheri Eriophorum angustifolium Eriophorum scheuchzeri flower Eriophorum spp. flowers Cyperacea leaf Cyperacea culm Cyperacea fruit/flower Equisetum variegatum Herbs Cardamine sp. Pedicularis sudetica Polygonum viviparum Saxifraga hirculus leaf Saxifraga hirculus flower Stellaria spp. Valeriana capitata Herb leaf Herb sepals Herb pistil Lichen Thamnolia vermicularis Dead and litter Carex spp. Cyperaceae Dupontia fisheri Dryas integrifolia Eriophorum angustifolium Vasc. bundles Salix spp. Botanical composition of esophagus fistula samples from the Dupontia fisheri type. (13 and 18 are from the Carex 22-25 13 26.0 14.5 15 3.5 3.0 3.5 67.0 5.0 6.0 55.5 0.5 3:5 3.0 0.5 0.5 0.5 2:5 0.5 2.0 Appendix Table 3 aquatilis type.) Percent. 58-67 14 15 16 23.5 15.0 22.5 0.5 13.0 10.5 14.0 2.0 0.5 0.5 1.0 6.0 3.5 55 1.5 25 19.0 69.0 54.5 21:5 6.0 0.5 5.0 3.5 6.0 8.0 27.5 33.5 3.5 ohh) 8.5 1.0 2.0 54.0 11.0 15.5 1.0 0.5 0.5 3.5 0.5 0.5 2.0 0.5 0.5 1.0 0.5 1.5 44.5 10.0 12.0 1.0 0.5 0.5 5.0 4.5 1.0 3.0 3.0 5) 1.0 0.5 17 19.5 14.0 0.5 5 3.5 64.0 31.0 0.5 15 20.0 4.5 0.5 9.0 0.5 15 0.5 0.5 0.5 5.0 0.5 8.0 2.0 25 0.5 25 0.5 22-25 20.5 11.0 38.5 1.0 37.5 LS 1.0 3.5 3.0 47.42 Te 17.1 13.8 21.9 18.3 0.08 4.67 S.D. 8.3 23.48 18.1 0.18 2.62 191 Appendix Table 4 Botanical composition of esophagus fistula samples from Salix ovalifolia sand dunes. Percent. Corresponding vegetation plots 97-106 EF samples Shrubs Salix ovalifolia leaf Salix ovalifolia stem Salix ovalifolia veins Grass Dupontia fisheri Elymus arenarius Herbs Artemesia spp. Chrysanthemum integrifolium Parrya nudicaulis Polemonium boreale Primula spp. Poligonum viviparum Herb leaf Herb flower Herb pistil Dead Dupontia fisheri Salix ovalifolia 192 Appendix Table 5 Botanical composition in 33 x 100 cm plots from Dryas integrifolia dry heaths. Percent. Stand no. Corresponding EF samples Plot no. Shrubs Arctostaphylos alpina Arctostaphylos rubra Dryas integrifolia Cassiope tetragona Salix arctica Salix ovalifolia Salix reticulata Salix lanata Salix rotundifolia Grass-like Arctagrostis latifolia Carex aquatilis Carex scirpoidea Dupontia fisheri Eriophorum angustifolium Festuca rubra Carex rupestris Equisetum variegatum Herbs Astragalus sp. Draba alpina Oxytropis arctica Oxytropis sp. Pedicularis arctica Pedicularis capitata Polygonum viviparum Polemonium boreale Saxifraga oppositifolia Silene acaulis Papaver sp. Parrya nudicaulis Lichen Dactylina arctica Cetraria ericetorum Thamnolia vermicularis Mosses Bryum sp. Dicranum sp. Other Dead and litter Bare ground Standing dead 4 3 2 > oO i) (= r=] (S ro} & Lo 2 2 co = x z S a 2 z Wi 12 13) 14S Sees Shrubs Dryas integrifolia Salix arctica Salix lanata Salix ovalifolia Salix reticulata Salix rotundifolia Salix pulchra Grass-like Carex membranacea Eriophorum angustifolium Eriophorum scheuzeri Equisetum variegatum Dupontia fisheri Herbs Braya spp. Draba alpina Parrya nudicaulis Polygonum viviparum Pedicularis sudetica Saxifraga oppositifolia Saxifraga cernua Stellaria crassifolia Lichen Thamnolia vermicularis Mosses Bryum spp. Dicranum sp. Other Standing dead Humus 195 Appendix Table 6 (continued) 6,7 13,18 22 DARE 25) 2G 27 28020 SON Xo OC 23 13a) 19: 920" 210 x 7 2 LO LO O 0M Oo j LO wu CO mowWMWo YN N N N 3 mo wom Tote ) + - Lo i cxf es: LO wow ica ) | iWelica! Aw apl 196 Appendix Table 7 Botanical composition in 33 x 100 cm plots from Dupontia fisheri meadows. Percent. Stand no. Corresponding EF samples Plot no. Shrubs Salix arctica Salix lanata Salix ovalifolia Salix reticulata Salix rotundifolia Salix pulchra Grass-like Carex aquatilis Carex membranacea Dupontia fisheri Eriophorum angustifolium Eriophorum scheuchzeri Equisetum variegatum Alopecurus alpinus Poa alpina Arctagrostis latifolia Juncus biglumis Herbs Braya spp. Cardamine pratensis Melandrium apetalum Ranunculus nivalis Pedicularis sudetica Polygonum viviparum Saxifraga cernua Saxifraga hirculus Stellaria spp. Valeriana capitata Oxytropis sp. Parrya nudicaulis Mosses Mnium spp. Standing dead Humus/sand 1 14,15,16 and 17 58 59 60 61 62 63 64 65 66 67 68 = OY, Appendix Table 7 (continued) 70 69 Appendix Table 8 Botanical composition in 33 x 100 cm plots from Carex aquatilis marshes. Percent. Stand no. Corresponding EF samples Plot no. Shrubs Salix lanata Salix ovalifolia Salix rotundifolia Grass-like Alopecurus alpinus Arctophila fulva Carex aquatilis Carex membranacea Dupontia fisheri Eriophorum angustifolium Eriophorum scheuchzeri Equisetum variegatum Herbs Cardamine pratensis Pedicularis sudetica Polygonum viviparum Viola sp. Lichen Cetraria cucullata Cetraria islandica Dactylina arctica Thamnolia vermicularis Mosses Dicranum fuscescens Mnium spp. Standing dead Sand/humus Water ~ foe) ~S o © o 81 82 83 ee) oS SS 199 Appendix Table 8 (continued) X3 x 94 93 92 Sl 90 x2 89 88 87 86 85 eS: = = Ww 200 Appendix Table 9 Botanical composition in 33 x 100 cm vegetation plots from the Sa/ix ovalifolia sand dunes. Percent. Stand no. Corresponding EF samples Plot no. Shrubs Salix ovalifolia Grass-like Arctagrostis latifolia Dupontia fisheri Elymus mollis Herbs Artemisia spp. Aster spp. Braya spp. Cardamine pratensis Cerastium beeringianum Draba alpina Lupinus arcticus Oxytropis arctica Pedicularis capitata Polemonium boreale Polygonum viviparum Primula borealis Sand/gravel 1 19,20 95 96 97 98 99 100 101 102 103 104 105 106 107 108 201 Appendix Table 10 (Walker, S., Pers. Comm.). Distribution of Dryas integrifolia, Eriophorum angustifolium and Carex aquatilis through vegetation types making up the continuum at Prudhoe Bay. Mean cover score and frequency for 10 quadrants randomly selected from each vegetation type. Webber/Walker Vegetation Type Plant species Type 1 Type 2 Type 3 Type 4 Type 5 Type 6 Dryas integrifolia 48.7(100) 59.8(100) 20(90) Eriophorum angustifolium 2.4(40) 11.0(80) 11.6(90) 23.2(90) 7.5(70) Carex aquatilis 4.0(40) 11.2(60) 17.5(100) 19.0(100) 16.5(80) Comments from Walker: 1. Type 2 may be equivalent to Skogland’s Dryas integrifolia community, but Skogland may have been ignoring crustose lichens, which we use as an indicator for Type 1. Probably, plots were in both of Types 1 and 2. Also plot No. 34 was probably what we would call Type 9—snowbed community. 2. Although we show greatest coverage by Eriophorum angustifolium in Type 4, to say that Type 4 is equivalent to Skogland’s “Eriophorum angustifolium” may be in error since the presence of Dryas is to be found in analyses of nearly all of his plots; we rarely recorded much Dryas in Type 4. Skogland’s Eriophorum angustifolium marsh may correspond more closely to Type 3, but it should not be designated as “polygon marsh.”" 3. Skogland’s Carex aquatilis marshes are probably a mixture of our Types 4 and 5. Type 4 is relatively dry by the end of summer (i.e., there’s little or no standing water); whereas, Type 5 has standing water throughout the summer. These are both truly marshy types. The Dupontia fisheri meadows seem to correspond most closely to Type 12 vegetation which was found mostly along streambanks and the edges of some lakes. It is not very common and probably does not fit into the generalized moisture continuum which occurs over the majority of the region. 3 at, SD .. - . 7 eh A eel a” © Su >» 203 Appendix A Provisional Checklist to the Vaseular, Bryophyte, and Lichen Flora of Prudhoe Bay, Alaska BARBARA M. MURRAY and DAVID F. MURRAY University of Alaska Herbarium Fairbanks, Alaska 99701 Introduction Prudhoe Bay is situated on the Arctic Coast- al Plain, a distinct physiographic unit that ex- tends from Point Lay east across northern Alas- ka to the Mackenzie Delta in Canada. The flora is characteristic of a wet lowland that is inter- rupted chiefly by thaw lakes, drained lake basins, and river systems. The differences be- tween the Prudhoe flora and that of Barrow and environs can be attributed to the physical fea- tures associated with the large rivers that head in the Brooks Range, numerous pingos, and dis- tinctly calcareous soils. The areas collected were adjacent to the road system that links drilling pads and related facilities between the Sagav- anirktok and Kuparuk rivers. We and others were able to visit and examine gravel bars, riverbanks, sand dunes, pingos, thaw lakes, drained lake basins, saline marshes, and _ ice- wedge polygons. Thus, a full spectrum of habitats was included in the inventory. Floristic studies of the Prudhoe Bay area are still in the exploratory stage, and the following list is provisional. The first plant collections resulted from Tundra Biome studies; since 1971 Tundra Biome participants and cooperators have been expanding our knowledge of the flora of the area through collections (Table 1) and reports. The only published list for the area is that of Rastorfer, Webster, and Smith (1973) who reported their own 1972 bryophyte collec- tions. In a few cases they listed species without citing specimens, and according to J. R. Rastorfer jn /itt., 1974, no vouchers were kept for these taxa. In the following list we have placed these undocumented reports in brackets, if we were unable to find a specimen to substan- tiate the occurrence of the species at Prudhoe Bay. Table 1 Collectors of vascular plants (V), bryophytes (B), and lichens (L) M. W. Battrum (1971) B, L J. W. Batty (1973, 1974) V, B,L J. Hok (1971) V B. M. Murray (1971, 1972, 1974) B, L D. F. Murray (1971, 1972, 1974) V J. R. Rastorfer, H. J. Webster, and D. K. Smith (1972) B D.H.S. Richardson (1974) L E. Schofield (1972) V, L W. C. Steere (1972); W. C. Steere and Z. Iwatsuki (1974) B D. A. Walker (1973, 1974) V, B, L H. J. Webster (1971) B M. E. Williams (1972) V, L 204 This list represents the first report of vascu- lar plants and lichens for the Prudhoe Bay area and includes further records of bryophytes. These records are excerpted from our Tundra Biome final project report. We have cited a single specimen of each taxon in order to docu- ment its presence in the Prudhoe Bay area and have not cited all collections seen. Unless other- wise stated, specimens are in the University of Alaska Herbarium (ALA), and_ identifications were made by the collectors. David F. Murray has verified the identification of all vascular plants cited. Other herbaria housing specimens cited are the University of Calgary Herbarium (UAC) and The New York Botanical Garden (NY). Generally, nomenclature follows Hultén (1968, 1973) for vascular plants; Worley (1970) for hepatics; Crum, Steere, and Anderson (1973) for mosses, excluding Mniaceae; Koponen (1968, 1972) for Mniaceae; and Hale and Cul- berson (1970) for lichens. Synonyms are in- cluded when they facilitate referral to specimens er when they are commonly used. Acknowledgments We wish to thank Tundra Biome personnel who sent us specimens and helped in the com- pilation of this report, especially M. W. Battrum, J. R. Rastorfer, D.A. Walker, and M.€E. Williams. We are deeply indebted to John W. Thomson, University of Wisconsin, Madison, who determined or verified most of the lichen specimens cited. William C. Steere, of The New York Botanical Garden, generously provided help with identifications in the field and in the laboratory. We are also grateful to him for permitting us to cite his unpublished collections from Prudhoe Bay. This project was supported through grants and contributions by the National Science Foundation under Grant GV 29342 to the Uni- versity of Alaska, the State of Alaska, and the Prudhoe Bay Environmental Subcommittee. It was performed under the joint NSF sponsorship of the International Biological Program and the Office of Polar Programs and was directed under the auspices of the U. S. Tundra Biome. Floristic Notes Noteworthy discoveries are: 1. Puccinellia andersonii has been known in Alaska only from its type locality at Point Lay. The Prudhoe collection bridges a gap between Point Lay and Banks Island, Northwest Terri- tories (A. E. Porsild, /n /itt.). 2. Thlaspi arcticum was found on a gravel terrace of the Kuparuk River. Numerous plants were seen which, in itself, is unusual. A collec- tion by Spetzman from the Sadlerochit River (Wiggins and Thomas 1962) is the only other Alaskan collection. This taxon is currently under study to determine its relationship to the Asian T. cochleariforme, but sufficient material is not available from all stages of development to adequately describe it. We are now examining the series of 7. arcticum we obtained, but viable seed would be most helpful. Since the locality of our collection is a gravel terrace adjacent to gravel deposits already mined for fill, this site should be identified so it can be protected. It is the only readily accessible source of this species. Thlaspi arcticum has now been placed on the Smithsonian list of threatened species, and this Prudhoe site should be protected from further disturbance. 3. The lichens Lopadium fecundum, Poly- blastia bryophila, and P. sendtner/ have not been previously reported for Alaska, according to J. W. Thomson in //tt. References Crum, H., W.C. Steere, and L.E. Anderson (1973). A new list of mosses of North America north of Mexico. Bryo/ogist, 76:85-130. Hale, M.E., Jr. and W. L. Culberson (1970). A fourth checklist of the lichens of the con- tinental United States and Canada. Bryo- logist, 73:499-543. Halliday, G. and A.O. Chater (1969). Carex marina Dewey, an earlier name for C. amblyorhyncha Krecz. Feddes Repertorium, 80: 103-106. Hultén, E. (1968). ‘Flora of Alaska and Neigh- boring Territories.” Stanford University Press, Stanford, 1008 pp. Hultén, E. (1973). Supplement to Flora of Alaska and Neighboring Territories. Bot. Not., 126:459-512. Koponen, T. (1968). Generic revision of Mniaceae Mitt. (Bryophyta). Ann. Got. Fenn., 5:117-151. . (1972). Notes on Mnium arizonicum and VM. thomsonii. Lindbergia, 1:161-165. Mulligan, G. A. (1974). Confusion in the names of three Draba species of the Arctic: D. adamsii, D. oblongata, and D. corymbosa. Can. J. Bot., 52:791-793. Rastorfer, J. R., H. J. Webster, and D. K. Smith (1973). Floristic and ecologic studies of bryophytes of selected habitats at Prudhoe Bay, Alaska. The Ohio State University, Institute of Polar Studies, Report No. 49, 20 pp. 205 Steere, W. C. (1974). The status and geographi- cal distribution of Vo/tia hyperborea in North America (Musci: Splachnaceae). Bu//. Torrey Bot. Club, 101:55-63. Steere, W.C. and B.M. Murray (1974). The geographical distribution of Bryum wrighti/ in arctic and boreal North America. Bryo- logist, 77:172-178. Wiggins, |. L. and J. H. Thomas (1962). A flora of the Alaskan Arctic Slope. University of Toronto Press, Toronto, 425 pp. Worley, |. A. (1970). A checklist of the Hepati- cae of Alaska. Bryo/ogist, 73:32-38. VASCULAR PLANTS AGROPY RON BOREALE (Turcz.) Drobov ssp. HYPERARCTICUM (Pols.) Meld. D. Murray 4575 ALOPECURUS ALPINUS Sm. ssp. ALPINUS D. Murray 3410 ANDROSACE CHAMAEJASME Host ssp. LEHMANNIANA (Spreng.) Hult. D. Murray 3387 ANDROSACE SEPTENTRIONALIS L. D. Murray 4505 ANEMONE PARVIFLORA Michx. D. Murray 4537 ANEMONE RICHARDSONII Hook. D. Murray 4537 ANTENNARIA FRIESIANA (Trautv.) Ekman ssp. ALASKANA (Malte) Hult. D. Murray 4577 ARABIS LYRATA L. ssp. KAMCHATICA (Fisch.) Hult. D. Murray 3359 ARCTAGROSTIS LATIFOLIA (R. Br.) Griseb. var. LATIFOLIA D. Murray 4554 ARCTOPHILA FULVA (Trin.) Anderss. D. Murray 4555 ARCTOSTAPHYLOS RUBRA (Rehd. & Wils.) Fern. D. Murray 4567 ARMERIA MARITIMA (Mill.) Willd. ssp. ARCTICA (Cham.) Hult. D. Murray 3356 ARTEMISIA ARCTICA Less. ssp. ARCTICA D. Murray 4568 ARTEMISIA BOREALIS Pall. (including A. richardsoniana Bess.) D. Murray 3356 ARTEMISIA GLOMERATA Ledeb. D. Murray 4532 ARTEMISIA TILESII Ledeb. ssp. TILESI| D. Murray 4569 ASTER SIBIRICUS L. D. Murray 4574 ASTRAGALUS ALPINUS L. D. Murray 4540 ASTRAGALUS UMBELLATUS Bunge _ D. Murray 4517 BOYKINIA RICHARDSONII (Hook.) Gray Walker 503 BRAYA PILOSA Hook. D. Murray 3383 BRAYA PURPURASCENS (R. Br.) Bunge D. Murray 3385 BROMUS PUMPELLIANUS Scribn. var. ARCTICUS (Shear) Pors. Walker 570 CALTHA PALUSTRIS L. ssp. ARCTICA (R. Br.) Hult. D. Murray 4512 CAMPANULA UNIFLORA L. D. Murray 3398 CARDAMINE DIGITATA Richards. (= C. hyperborea Schulz) D. Murray 3399 CARDAMINE PRATENSIS L. ssp. ANGUSTIFOLIA (Hook.) Schulz Wa/ker 549 CAREX AQUATILIS Wahlenb. (s.l., to include C. stans Drej.) CAREX ATROFUSCA Schk. D. Murray 3370 CAREX BIGELOWII Torr. D. Murray 3416 D. Murray 3586 CAREX MARINA Dewey (= C. amblyorhyncha Krecz., Halliday and Chater 1969) Wa/ker 4, det. A. Batten CAREX MARITIMA Gunn. D. Murray 4514 CAREX MEMBRANACEA Hook. Wa/ker s.n., 5 August 1974, det. D. Murray 206 Vascular Plants (continued) CAREX MISANDRA R. Br. D. Murray 3384 CAREX RARIFLORA (Wahlenb.) J.E. Sm. D. Murray 3364 CAREX RUPESTRIS All. D. Murray 4583 CAREX SAXATILIS L. ssp. LAXA (Trautv.) Kalela | Wa/ker s.n., 5 August 1974 CAREX SCIRPOIDEA Michx. D. Murray 4519 CAREX SUBSPATHACEA Wormsk. Wa/ker & Batty PBO39 CAREX URSINA Dew. D. Murray 3406 CAREX VAGINATA Tausch Walker 526 CASSIOPE TETRAGONA (L.) D. Don ssp. TETRAGONA D. Murray 4539 CERASTIUM BEERINGIANUM Cham. & Schlecht. var. BEERINGIANUM_ D. Murray 4538 CHRYSANTHEMUM INTEGRIFOLIUM Richards. D. Murray 3394 CHRYSOSPLENIUM TETRANDRUM (Lund) Th. Fr. D. Murray 4525 COCHLEARIA OFFICINALIS L. ssp. ARCTICA (Schlecht.) Hult. D. Murray 4577 DESCHAMPSIA CAESPITOSA (L.) Beauv. ssp. ORIENTALIS Hult. D. Murray 3412 DRABA ALPINA L. D. Murray 3387, det. G. A. Mulligan DRABA CINEREA Adams D. Murray 3402, det. G. A. Mulligan DRABA CORYMBOSA R. Br. ex DC. (= D. bel/ii Holm, D. macrocarpa Adams, Mulligan 1974) D. Murray 3377, det. G. A. Mulligan DRABA LACTEA Adams_ D. Murray 3382, det. G. A. Mulligan DRYAS INTEGRIFOLIA M. Vahl ssp. INTEGRIFOLIA D. Murray 4533 DUPONTIA FISHERI R. Br. ssp. PSILOSANTHA (Rupr.) Hult. D. Murray 4563 ELYMUS ARENARIUS L. ssp. MOLLIS (Trin.) Hult. var. VILLOSISSIMUS (Scribn.) Hult. D. Murray 3411 EPILOBIUM LATIFOLIUM L. Walker 557 EQUISETUM ARVENSE L. D. Murray 4515 EQUISETUM SCIRPOIDES Michx. D. Murray 3380 EQUISETUM VARIEGATUM Schleich. D. Murray 4565 ERIGERON ERIOCEPHALUS J. Vahl D. Murray 4545 ERIGERON HUMILIS Grah. D. Murray 3378 ERIOPHORUM ANGUSTIFOLIUM Honck. ssp. SU\BARCTICUM (Vassil.) Hult. Wa/ker s.n., 5 August 1974 ERIOPHORUM SCHEUCHZERI Hoppe var. SCHEUCHZERI D. Murray 3405 ERIOPHORUM TRISTE (Th. Fr.) Hadac & Léve (= E. angustifolium ssp. triste) D. Murray 3375 ERIOPHORUM VAGINATUM L. D. Murray 4550 EUTREMA EDWARDSII R. Br. D. Murray 3368 FESTUCA BAFFINENSIS Polunin D. Murray 3417 FESTUCA BRACHYPHYLLA Schult. D. Murray 4564 FESTUCA RUBRA LL. D. Murray 3415 GENTIANA PROSTRATA Haenke_ D. Murray 4556 GENTIANELLA PROPINQUA (Richards.) J. M. Gillett ssp. PROPINQUA (= Gentiana propinqua) D. Murray 3407 HIEROCHLOE PAUCIFLORA R. Br. Walker 7 HIPPURIS VULGARIS L. D. Murray 4552 JUNCUS ARCTICUS Willd. ssp. ALASKANUS Hult. D. Murray 4553 JUNCUS BIGLUMIS L. D. Murray 4560 JUNCUS CASTANEUS Sm. ssp. CASTANEUS_ D. Murray 3404 JUNCUS TRIGLUMIS L. ssp. ALBESCENS (Lange) Hult. Wa/ker & Batty s.n., August 1974 KOBRESIA MYOSUROIDES (Vill.) Fiori & Paol. D. Murray 4557 KOBRESIA SIBIRICA Turcz. D. Murray 3352 LAGOTIS GLAUCA Gaertn. ssp. MINOR (Willd.) Hult. D. Murray 4526 LESQUERELLA ARCTICA (Wormsk.) Wats. D. Murray 3395 LLOYDIA SEROTINA (L.) Rehb. D. Murray 3390 LUZULA ARCTICA Blytt D. Murray 4580 207 MINUARTIA ARCTICA (Stev.) Aschers. & Graebn. D. Murray 3379 MINUARTIA ROSSI (R. Br.) Graebn. Schofield & Williams P-G16 MINUARTIA RUBELLA (Wahlenb.) Graebn. D. Murray 3403 ORTHILIA SECUNDA (L.) House ssp. OBTUSATA (Turcz.) Bocher (= Pyrola secunda ssp. obtusata) Walker & Batty PBOO5 OXYRIA DIGYNA (L.) Hill D. Murray 4520 OXYTROPIS ARCTICA R. Br. D. Murray 3396 OXYTROPIS BOREALIS DC. D. Murray 4559 OXYTROPIS DEFLEXA (Pall.) DC. var. FOLIOLOSA (Hook.) Barneby D. Murray 4584 OXYTROPIS MAYDELLIANA Trautv. D. Murray 4513 OXYTROPIS NIGRESCENS (Pall.) Fisch. ssp. BRYOPHILA (Greene) Hult. D. Murray 4547 PAPAVER LAPPONICUM (Tolm.) Nordh. ssp. OCCIDENTALE (Lundstr.) Knaben D. Murray 4527 PAPAVER MACOUNII Greene D. Murray 3377 PARNASSIA KOTZEBUEI Cham. & Schlecht. D. Murray 4570 PARRYA NUDICAULIS (L.) Regel. ssp. NUDICAULIS D. Murray 3408 PEDICULARIS CAPITATA Adams D. Murray 3386 PEDICULARIS LANATA Cham. & Schlecht. (= P. kane Durand) D. Murray 3556 PEDICULARIS LANGSDORFFII Fisch. ssp. ARCTICA (R. Br.) Pennell D. Murray 3362 PEDICULARIS SUDETICA Willd. D. Murray 3391 PEDICULARIS SUDETICA Willd. ssp. ALBOLABIATA Hult. D. Murray 3372 PETASITES FRIGIDUS (L.) Franch. D. Murray 4582 POA ABBREVIATA R. Br. Walker 550, det. D. F. Murray POA ALPIGENA (Fr.) Lindm. D. Murray 4576 POA GLAUCA M. Vahl D. Murray 3419 POLEMONIUM BOREALE Adams_ D. Murray 3353 POLY GONUM BISTORTA L. ssp. PLUMOSUM (Small) Hult. Wa/ker 528 POLYGONUM VIVIPARUM L. D. Murray 3389 POTENTILLA HOOKERIANA Lehm. ssp. HOOKERIANA D. Murray 3407 POTENTILLA PULCHELLA R. Br. D. Murray 3358 POTENTILLA UNIFLORA Ledeb. D. Murray 4529 PRIMULA BOREALIS Duby D. Murray 4510 PUCCINELLIA ANDERSONII Swallen D. Murray 3474, ver. A. E. Porsild PUCCINELLIA PHRYGANODES (Trin.) Scribn. & Merr. D. Murray 4567 PYROLA GRANDIFLORA Radius Walker 545 RANUNCULUS NIVALIS L. D. Murray 3555 RANUNCULUS PEDATIFIDUS Sm. ssp. AFFINIS (R. Br.) Hult. D. Murray 4536 RANUNCULUS TRICHOPHYLLUS (E. Fr.) E. Fr. Walker 532 SAGINA INTERMEDIA Fenzl D. Murray 4562 SALIX ALAXENSIS (Anderss.) Cov. var. ALAXENSIS D. Murray 4566 SALIX ARCTICA Pall. D. Murray 4523 SALIX LANATA L. ssp. RICHARDSONII (Hook.) Skvortz. D. Murray 3351 SALIX OVALIFOLIA Trautv. var. OVALIFOLIA D. Murray 3366 SALIX PLANIFOLIA Pursh ssp. PULCHRA (Cham.) Argus var. PULCHRA_ D. Murray 4522 SALIX RETICULATA L. ssp. RETICULATA D. Murray 4534 SALIX ROTUNDIFOLIA Trautv. ssp. ROTUNDIFOLIA D. Murray 4548 SAUSSUREA ANGUSTIFOLIA (Willd.) DC. Walker 555 SAXIFRAGA CAESPITOSA L. D. Murray 4546 SAXIFRAGA CERNUA L. D. Murray 4547 SAXIFRAGA HIERACIFOLIA Waldst. & Kit. D. Murray 4543 SAXIFRAGA HIRCULUS L. D. Murray 3369 SAXIFRAGA OPPOSITIFOLIA L. ssp. OPPOSITIFOLIA D. Murray 4524 208 Vascular Plants (continued) SAXIFRAGA TRICUSPIDATA Rottb. D. Murray 4544 SEDUM ROSEA (L.) Scop. ssp. INTEGRIFOLIUM (Raf.) Hult. D. Murray 3354 SENECIO ATROPURPUREUS (Ledeb.) Fedtsch. ssp. FRIGIDUS (Richards.) Hult. D. Murray 3365 SENECIO CONGESTUS (R. Br.) DC. Walker s.n., July 1974 SENECIO RESEDIFOLIUS Less. D. Murray 3376 SILENE ACAULIS L. D. Murray 4535 SILENE INVOLUCRATA (Cham. & Schlecht.) Bocq. (= Melandrium affine J. Vahl) D. Murray 3373 SILENE WAHLBERGELLA Chawd. ssp. ARCTICA (Fr.) Hult. (= Melandrium apetalum (L.) Fenzl ssp. arcticum (Fr.) Hult.) D. Murray 3363 STELLARIA HUMIFUSA Rottb. Walker & Batty PBO37 STELLARIA LAETA Richards. D. Murray 4549 TARAXACUM CERATOPHORUM (Ledeb.) DC. D. Murray 3355 TARAXACUM PHYMATOCARPUM J. Vahl D. Murray 3397 THALICTRUM ALPINUM L. D. Murray 3392 THLASP!I ARCTICUM Pors. D. Murray 4530 TOFIELDIA PUSILLA (Michx.) Pers. Walker & Batty PBO28 TRISETUM SPICATUM (L.) Richt. D. Murray 3413 UTRICULARIA VULGARIS L. ssp. MACRORHIZA (Le Conte) Clausen Wa/ker s.n., 5 August 1974, det. D. Murray VALERIANA CAPITATA Pall. D. Murray 4557 WILHELMSIA PHYSODES (Fisch.) McNeill D. Murray 4528 BRYOPHYTES Hepatics ANEURA PINGUIS (L.) Dum. (= Riccardia pinguis) Rastorfer, Webster, and Smith 1973 ARNELLIA FENNICA (Gott.) Lindb. Wa/ker 52, det. W. C. Steere BLEPHAROSTOMA TRICHOPHYLLUM (L.) Dum. Rastorfer, Webster, and Smith 1973; var. BREVIRETE Bryhn & Kaalaas Rastorfer, Webster, and Smith 1973 [CEPHALOZIELLA ARCTICA Bryhn & Douin Rastorfer, Webster, and Smith 1973, no specimen cited] CLEVEA HYALINA (Sommerf.) Lindb. B. Murray 6275, det. W. C. Steere MARCHANTIA ALPESTRIS Nees 8. Murray 4417, det. K. Damsholt MARCHANTIA POLYMORPHA L. Rastorfer, Webster, and Smith 1973, no specimen cited, B. Murray 4428 MESOPTYCHIA SAHLBERGII (Lindb. & H. Arnell) Evans Walker 37, det. W. C. Steere ODONTOSCHISMA MACOUNII (Aust.) Und. Rastorfer, Webster, and Smith 1973 PLAGIOCHILA ARCTICA Bryhn & Kaal. Wa/ker 77, det. W. C. Steere PREISSIA QUADRATA (Scop.) Nees B. Murray 6243 PTILIDIUM CILIARE (Web.) Hampe_ Rastorfer, Webster, and Smith 1973 RADULA PROLIFERA H. Arnell Rastorfer, Webster, and Smith 1973 [SCAPANIA IRRIGUA (Nees) Dum. Rastorfer, Webster, and Smith 1973, no specimen cited] TRITOMARIA QUINQUEDENTATA (Huds.) Buch Rastorfer, Webster, and Smith 1973 Mosses ALOINA BREVIROSTRIS (Hook. & Grev.) Kindb. 8B. Murray 6237 (mainly Polyblastia) APLODON WORMSKJOLDII (Hornem.) R. Br. (= Haplodon wormskjoldii) Rastorfer, Webster, and Smith 1973 AULACOMNIUM ACUMINATUM (Lindb. & H. Arnell) Kindb. Rastorfer, Webster, and Smith 1973 AULACOMNIUM PALUSTRE (Hedw.) Schwaegr. Rastorfer, Webster, and Smith 1973 AULACOMNIUM TURGIDUM (Wahlenb.) Schwaegr. Rastorfer, Webster, and Smith 1973 [BARBULA ICMADOPHILA Schimp. ex C. Muell. Rastorfer, Webster, and Smith 1973, no specimen cited] [BRACHYTHECIUM TURGIDUM (C. J. Hartm.) Kindb. Rastorfer, Webster, and Smith 1973, no specimen cited] 209 BRYOBRITTONIA PELLUCIDA Williams 8. Murray 6247 BRYOERYTHROPHYLLUM RECURVIROSTRUM (Hedw.) Chen (= Didymodon recurvirostris) Rastorfer, Webster, and Smith 1973 BRYUM ARCTICUM (R. Br.) B.S.G. Rastorfer, Webster, and Smith 1973 BRYUM ARGENTEUM Hedw. 8B. Murray 6249 BRYUM cf. CAESPITICIUM Hedw. Walker 24, det. W. C. Steere [BRYUM CALOPHYLLUM R. Br. Rastorfer, Webster, and Smith 1973, no specimen cited] BRYUM CRYOPHILUM Mart. 8. Murray 6248 BRYUM PALLESCENS Schleich. ex Schwaegr. Rastorfer, Webster, and Smith 1973 BRYUM STENOTRICHUM C. Muell. (= 8. inclinatum) Rastorfer, Webster, and Smith 1973 BRYUM WRIGHTII Sull. & Lesq. Steere and Murray 1974 CALLIERGON GIGANTEUM (Schimp.) Kindb. Rastorfer, Webster, and Smith 1973, no specimen cited, Steere 72- 718 (NY) CALLIERGON ORBICULARICORDATUM (Ren. & Card.) Broth. Steere 72-665 (NY) CALLIERGON RICHARDSONII (Mitt.) Kindb. ex Warnst. Rastorfer, Webster, and Smith 1973; var. ROBUSTUM (Lindb. & Arn.) Broth em. Kar. 8. Murray 6220 [CALLIERGON SARMENTOSUM (Wahlenb.) Kindb. Rastorfer, Webster, and Smith 1973, no specimen cited] CALLIERGON TRIFARIUM (Web. & Mohr) Kindb. Steere /n /itt., 1974 (NY) CAMPYLIUM STELLATUM (Hedw.) C. Jens. Rastorfer, Webster, and Smith 1973 CATOSCOPIUM NIGRITUM (Hedw.) Brid. Rastorfer, Webster, and Smith 1973 CERATODON PURPUREUS (Hedw.) Brid. Rastorfer, Webster, and Smith 1973 CINCLIDIUM ARCTICUM (B.S.G.) Schimp. Rastorfer, Webster, and Smith 1973 CINCLIDIUM LATIFOLIUM Lindb. Rastorfer, Webster, and Smith 1973 CIRRIPHYLLUM CIRROSUM (Schwaegr. ex Schultes) Grout Rastorfer, Webster, and Smith 1973 CRATONEURON ARCTICUM Steere Walker 49, det. W. C. Steere CRATONEURON FILICINUM (Hedw.) Spruce Steere 72-739 (NY) CTENIDIUM MOLLUSCUM (Hedw.) Mitt. Walker 29, det. W. C. Steere [CY RTOMNIUM HYMENOPHYLLOIDES (Hueb.) Kop. (= Mnium hymenophylloides) Rastorfer, Webster, and Smith 1973, no specimen cited] CYRTOMNIUM HYMENOPHYLLUM (B.S.G.) Holmen (= Mnium hymenophyllum) Rastorfer, Webster, and Smith 1973 DESMATODON HEIMII (Hedw.) Mitt. (= Pottia heimii) B. Murray 4472 DESMATODON LEUCOSTOMA (R. Br.) Berggr. (= D. suberectus) Rastorfer, Webster, and Smith 1973 [DICRANELLA CRISPA (Hedw.) Schimp. (= Anisothecium crispum) Rastorfer, Webster, and Smith 1973, no specimen cited] DICRANUM ANGUSTUM Lindb. Rastorfer, Webster, and Smith 1973 DICRANUM ELONGATUM Schleich. ex Schwaegr. Rastorfer, Webster, and Smith 1973 DIDYMODON ASPERIFOLIUS (Mitt.) Crum, Steere & Anderson 8. Murray 4446 DISTICHIUM CAPILLACEUM (Hedw.) B.S.G. Rastorfer, Webster, and Smith 1973 DISTICHIUM HAGENII Ryan ex Philib. Rastorfer, Webster, and Smith 1973 DISTICHIUM INCLINATUM (Hedw.) B.S.G. Rastorfer, Webster, and Smith 1973 DITRICHUM FLEXICAULE (Schwaegr.) Hampe Rastorfer, Webster, and Smith 1973 DREPANOCLADUS BADIUS (C. J. Hartm.) Roth Steere jn /itt., 1974 (NY) DREPANOCLADUS EXANNULATUS (B.S.G.) Warnst. Steere & /watsuki 74-317 (NY) DREPANOCLADUS LYCOPODIOIDES (Brid.) Warnst. Steere 72-737 (NY); var. BREVIFOLIUS (Lindb.) Moenk (= D. brevifolius) Rastorfer, Webster, and Smith 1973 DREPANOCLADUS REVOLVENS (Sw.) Warnst. Rastorfer, Webster, and Smith 1973 DREPANOCLADUS UNCINATUS (Hedw.) Warnst. ARastorfer, Webster, and Smith 28, det. B. Murray ENCALYPTA ALPINA Sm. Rastorfer, Webster, and Smith 1973, no specimen cited, Steere 72-707 (NY) ENCALYPTA PROCERA Bruch Rastorfer, Webster, and Smith 1973, no specimen cited, B. Murray 6244 ENCALYPTA RHAPTOCARPA Schwaegr. (= E. vu/garis var. rhaptocarpa) Rastorfer, Webster, and Smith 1973 ENCALYPTA VULGARIS Hedw. 8. Murray 6214 210 Bryophytes (continued) FISSIDENS ADIANTOIDES Hedw. Steere & /watsuki 74-318 (NY) FISSIDENS OSMUNDOIDES Hedw. Rastorfer, Webster, and Smith 1973 FUNARIA ARCTICA (Berggr.) Kindb. (= F. hygrometrica var. arctica, F. microstoma var. obtusifolia) B. Murray 6251 FUNARIA POLARIS Bryhn Rastorfer, Webster, and Smith 1973 GRIMMIA APOCARPA Hedw. Battrum 304 HYLOCOMIUM SPLENDENS (Hedw.) B.S.G. var. OBTUSIFOLIUM (Geh.) Par. (= H. a/askanum) Rastorfer, Webster, and Smith 1973 HYPNUM BAMBERGERI Schimp. Rastorfer, Webster, and Smith 1973 [HYPNUM CUPRESSIFORME Hedw. Rastorfer, Webster, and Smith 1973, no specimen cited] HYPNUM PROCERRIMUM Mol. B. Murray 4440 HYPNUM REVOLUTUM (Mitt.) Lindb. Wa/ker 55, det. W. C. Steere HYPNUM VAUCHERI Lesq. Rastorfer, Webster, and Smith 1973 LEPTOBRYUM PYRIFORME (Hedw.) Wils. 8. Murray 4412 MEESIA TRIQUETRA (Richt.) Angstr. Rastorfer, Webster, and Smith 1973 MEESIA ULIGINOSA Hedw. Rastorfer, Webster, and Smith 1973 MNIUM cf. BLYTTII B.S.G. B. Murray 4426, det. P. Gravesen MNIUM THOMSONII Schimp. (= MV. orthorrhynchum) Steere 72-683 (NY) MYURELLA JULACEA (Schwaegr.) B.S.G. Rastorfer, Webster, and Smith 1973 MYURELLA TENERRIMA (Brid.) Lindb. Rastorfer, Webster, and Smith 1973 ONCOPHORUS WAHLENBERGII Brid. Rastorfer, Webster, and Smith 1973 ORTHOTHECIUM CHRYSEUM (Schwaegr. ex Schultes) B.S.G. Rastorfer, Webster, and Smith 1973 ORTHOTHECIUM INTRICATUM (C. J. Hartm.) B.S.G. B. Murray 6234, det. W. C. Steere ORTHOTHECIUM RUFESCENS (Brid.) B.S.G. Steere 72-715 (NY) PHILONOTIS FONTANA (Hedw.) Brid. var. PUMILA (Turn.) Brid. (= P. tomentella) Steere 72-679 (NY) PHILONOTIS sp. Rastorfer, Webster, and Smith 1973 (as possibly P. fontana) [PLAGIOMNIUM RUGICUM (Laur.) Kop. (= Mnium rugicum) Rastorfer, Webster, and Smith 1973, no specimen cited] PLATYDICTYA JUNGERMANNIOIDES (Brid.) Crum Wa/ker 57, det. W. C. Steere POGONATUM ALPINUM (Hedw.) Roehl. var. SEPTENTRIONALE (Brid.) Brid. Rastorfer, Webster, and Smith 1973 POHLIA CRUDA (Hedw.) Lindb. Rastorfer, Webster, and Smith 1973 [POHLIA NUTANS (Hedw.) Lindb. Rastorfer, Webster, and Smith 1973, no specimen cited] RHACOMITRIUM LANUGINOSUM (Hedw.) Brid. Rastorfer, Webster, and Smith 1973 RHIZOMNIUM ANDREWSIANUM (Steere) Kop. (= Mnium andrewsianum) Steere in /itt., 1974 (NY) RHYTIDIUM RUGOSUM (Hedw.) Kindb. Rastorfer, Webster, and Smith 1973 SCORPIDIUM SCORPIOIDES (Hedw.) Limp. Rastorfer, Webster, and Smith 1973 SCORPIDIUM TURGESCENS (T. Jens.) Loeske (= Ca/liergon turgescens) Rastorfer, Webster, and Smith 1973 SPLACHNUM SPHAERICUM Hedw. (= S. ovatum) Rastorfer, Webster, and Smith 1973 .- SPLACHNUM VASCULOSUM Hedw. Rastorfer, Webster, and Smith 1973, no specimen cited, B. Murray 4415 STEGONIA LATIFOLIA (Schwaegr. ex Schultes) Vent. ex Broth. var. PILIFERA (Brid.) Broth. B. Murray 6246 TAYLORIA ACUMINATA Hornsch. 8. Murray 6249 TETRAPLODON MNIOIDES (Hedw.) B.S.G. Rastorfer, Webster, and Smith 1973; var. CAVIFOLIUS Schimp. (= T. urceolatus) Rastorfer, Webster, and Smith 1973 TETRAPLODON PARADOXUS ({R. Br.) Hag. (= 7. mnioides var. paradoxus, T. pallidus) B. Murray 6252 THUIDIUM ABIETINUM (Hedw.) B.S.G. (= Abjetinella abietina) Rastorfer, Webster, and Smith 1973 TIMMIA AUSTRIACA Hedw. B. Murray 4437, det. V. B. Lauridsen TIMMIA MEGAPOLITANA Hedw. var. BAVARICA (Hessl.) Brid. B. Murray 6235 TIMMIA NORVEGICA Zett. Rastorfer, Webster, and Smith 1973 TOMENTHYPNUM NITENS (Hedw.) Loeske (= Homalothecium nitens) Rastorfer, Webster, and Smith 1973 TORTELLA ARCTICA (Arn.) Crundw. & Nyh. Rastorfer, Webster, and Smith 68, det. B. Murray TORTELLA FRAGILIS (Drumm.) Limpr. 8B. Murray 6242 TORTULA MUCRONIFOLIA Schwaegr. 8B. Murray 6250 211 TORTULA RURALIS (Hedw.) Gaertn., Meyer & Scherb. Rastorfer, Webster, and Smith 1973 TRICHOSTOMUM CUSPIDATISSIMUM Card. & Ther. Walker s.n., 20 July 1974, det. B. Murray VOITIA HYPERBOREA Grev. & Arnott Steere 1974 Rejected moss taxa HYPNUM CALLICHROUM Funck ex Brid. Rastorfer, Webster, and Smith cited their collection number 28 as this species; the ALA specimen number 28 is Drepanocladus uncinatus. ONCOPHORUS VIRENS (Hedw.) Brid. Rastorfer, Webster, and Smith cited this species, but the ALA specimen of the collection (No. 60) they cited is O. wahlenbergii. VOITIA NIVALIS Hornsch. Rastorfer, Webster, and Smith cited their collections numbered 14, 73, and 85 as this species; Steere (1974) has recently discussed V. hyperborea and V. nivalis and cited Rastorfer, Webster, and Smith material as V. hyperborea. LICHENS ALECTORIA NIGRICANS (Ach.) Nyl. Schofield Ak-86, det. M. E. Williams ALECTORIA OCHROLEUCA (Hoffm.) Mass. 8B. Murray 6219 ASAHINEA CHRYSANTHA (Tuck.) W. Culb. & C. Culb. Williams Ak-652, det. B. Murray BUELLIA ALBOATRA (Hoffm.) Branth. & Rostr. Battrum 325A (UAC), det. C. D. Bird BUELLIA PAPILLATA (Somm.) Tuck. 8B. Murray 4355, det. J. W. Thomson CALOPLACA CINNAMOMEA (Th. Fr.) Oliv. 8B. Murray 6245 in part, det. J. W. Thomson CALOPLACA DISCOLOR (Will.) Fink 8B. Murray 6227 in part, det. J. W. Thomson CALOPLACA STILLICIDIORUM (Vahl) Lynge 8. Murray 6245 in part, det. J. W. Thomson CANDELARIELLA AURELLA (Hoffm.) Zahlbr. 8. Murray 6228, det. J. W. Thomson CANDELARIELLA XANTHOSTIGMA (Pers.) Lett.” B. Murray 62417, det. J. W. Thomson CETRARIA CUCULLATA (Bell.) Ach. 8. Murray 4331 CETRARIA DELISEI (Bory ex Schaer.) Th. Fr. B. Murray 4345 CETRARIA ISLANDICA (L.) Ach. 8. Murray 4335 CETRARIA NIVALIS (L.) Ach. 8. Murray 4330 CETRARIA RICHARDSONII Hook. B. Murray 4332 CETRARIA TILESII Ach. 8. Murray 4349 CLADONIA AMAUROCRAEA (Flérke) Schaer. Williams Ak-655, det. J. W. Thomson CLADONIA LEPIDOTA Nyl. Aichardson s.n. (ALA 61969), det. J. W. Thomson CLADONIA POCILLUM (Ach.) O. Rich. B. Murray 4350 CLADONIA SQUAMOSA (Scop.) Hoffm. Schofield Ak-91, det. M. E. Williams CLADONIA SUBFURCATA (Nyl.) Arn. Schofield Ak-90, det. J. W. Thomson COLLEMA BACHMANIANUM (Fink) Degel. (= C. tenax var. bachmanianum) B. Murray 4328, det. J. W. Thomson; var. MILLEGRANUM Degel. 8. Murray 4387, det. J. W. Thomson COLLEMA TUNAEFORME (Ach.) Ach. 8. Murray 4342, det. J. W. Thomson CORNICULARIA ACULEATA (Schreb.) Ach. 8B. Murray 4326 CORNICULARIA DIVERGENS Ach. B. Murray 6237 DACTYLINA ARCTICA (Hook.) Nyl. B. Murray 4333 DACTYLINA RAMULOSA (Hook.) Tuck. 8B. Murray 4329 EVERNIA PERFRAGILIS Llano B. Murray 4344, det. J. W. Thomson FULGENSIA BRACTEATA (Hoffm.) Ras. 8B. Murray 4363 GYALECTA FOVEOLARIS (Ach.) Schaer. B. Murray 4364, det. J. W. Thomson HYPOGYMNIA PHYSODES (L.) W. Wats. B. Murray 4400, det. J. W. Thomson — esorediate HYPOGYMNIA SUBOBSCURA (Vain.) Poelt 8B. Murray 4327 LECANORA BERINGII Nyl. Aichardson s.n. (ALA 61974), det. J. W. Thomson LECANORA EPIBRYON (Ach.) Ach. 8B. Murray 4337 LECANORA VERRUCOSA Ach. 8. Murray 4339 LECIDEA ASSIMILATA Nyl. Richardson s.n. (ALA 61975), det. J. W. Thomson DZ Lichens (continued) LECIDEA VERNALIS (L.) Ach. 8. Murray 4367, det. J. W. Thomson LEPRARIA MEMBRANACEA (Dicks.) Vain. 8. Murray 6240, det. J. W. Thomson LEPTOGIUM TENUISSIMUM (Dicks.) Fr. 8B. Murray 4347, det. J. W. Thomson LOPADIUM FECUNDUM Th. Fr. B. Murray 4396, det. J. W. Thomson OCHROLECHIA FRIGIDA (Sw.) Lynge 8. Murray 4396 in part; f. THELEPHOROIDES (Ach.) Lynge B. Murray 4395, det. J. W. Thomson OCHROLECHIA UPSALIENSIS (L.) Mass. 8B. Murray 4360, det. J. W. Thomson PARMELIA OMPHALODES (L.) Ach. 8B. Murray 4392 PARMELIELLA PRAETERMISSA (NylI.) P. James Aichardson s.n. (ALA 61971), det. J. W. Thomson PELTIGERA APHTHOSA (L.) Willd. B. Murray 4397 PELTIGERA CANINA (L.) Willd. B. Murray 4382 PELTIGERA MALACEA (Ach.) Funck 8. Murray 4325, det. J. W. Thomson PELTIGERA POLYDACTYLA (Neck.) Hoffm. Richardson s.n. (ALA 61970), det. B. Murray PELTIGERA RUFESCENS (Weis.) Humb. (=P. canina var. rufescens) B. Murray 4374, det. J. W. Thomson PELTIGERA SPURIA (Ach.) DC. f. SOREDIATA Schaer. (= P. canina var. rufescens f. sorediata) B. Murray 4340, det. J. W. Thomson PERTUSARIA OCTOMELA (Norm.) Erichs. 8. Murray 4394 PERTUSARIA PANYRGA (Ach.) Mass. B. Murray 4358, det. J. W. Thomson PERTUSARIA SUBOBDUCENS Nyl. 8. Murray 4338, det. J. W. Thomson PHYSCIA DUBIA (Hoffm.) Lett. 8B. Murray 6218 PHYSCONIA MUSCIGENA (Ach.) Poelt 8. Murray 4348 POLYBLASTIA BRYOPHILA Lonnr. 8B. Murray 6227, det. J. W. Thomson POLYBLASTIA SENDTNERI Kremph. 8. Murray 4386, det. J. W. Thomson RAMALINA ALMQUISTII Vain. 8B. Murray 4346 RHIZOCARPON DISPORUM (Naeg. ex Hepp) Mull. Arg. 8. Murray 4357 RINODINA ROSCIDA (Somm.) Arn. 8. Murray 4341 RINODINA TURFACEA (Wahlenb.) Kérb. 8. Murray 6238, det. J. W. Thomson SOLORINA SACCATA (L.) Ach. B. Murray 4362 SOLORINA SPONGIOSA (Sm.) Anzi 8B. Murray 4356 SPHAEROPHORUS GLOBOSUS (Huds.) Vain. Wa/kers.n., 22 August 1974, det. W. A. Weber STEREOCAULON ALPINUM Laur. 8. Murray 4375, det. |. M. Lamb ? STEREOCAULON RIVULORUM Magn. 8. Murray 4365, det. |. M. Lamb — too scanty to determine with certainty THAMNOLIA SUBULIFORMIS (Ehrh.) W. Culb. B. Murray 4336 TONINIA LOBULATA (Somm.) Lynge 8. Murray 6216, det. J. W. Thomson VERRUCARIA DEVERGENS Nyl. 8B. Murray 4354, det. J. W. Thomson XANTHORIA ELEGANS. B. Murray 4353 213 Appendix B Selected Data on Lichens, Mosses, and Vascular Plants on the Prudhoe Bay Tundra MICHAEL E. WILLIAMS*, EMANUEL D. RUDOLPH, and EDMUND A. SCHOFIELD** Institute of Polar Studies and Department of Botany The Ohio State University Columbus, Ohio 43210 Vegetation study plots were established at Prudhoe Bay 5-14 July 1972 in eight sites selected for their apparent homogeneity in rep- resenting various floristic communities (Fig. 1 and Table 1). Six plots were 10 m on each side, while the remaining two were 5m on each side. Samples of aboveground plant material, with the exception of loose vascular plant litter, were separated into moss, vascular plant, and lichen components, the latter by species. Ten 48 cm? samples were collected in each of the larger plots, and five samples in each of the smaller plots. The values for several abiotic parameters were also determined. Using random cores 7.2 cm in diameter and 10 cm deep, soil moisture, depth of thaw, and humus thickness were measured. Soil pH was obtained using the solu- tion from a 5:1 dilution of air-dried soil in deionized water, which was filtered 18 to 19 hrs later through a No. 120 soil sieve (115 mesh, 125 um opening). The pH was also determined for runoff water (i.e., the surface water nearest the study site to which the draining water would naturally flow). Conductivity was measured for both runoff water and aqueous extracts of soil. The results of these determinations are present- ed in Table 1. No clear correlation exists between standing crop of mosses or vascular plants and soil mois- ture. Lichens showed a direct relationship with substrate water content, with the exception of plots IV and V. The presence of a large number of tussocks in plot IV, which were considerably drier than the surrounding wet depressions, formed a suitable base for lichen colonization. The bryophyte standing crop was also relatively low here, as compared to other sites with high moisture. The apparent reason for the absence of lichens in plot V, in spite of the relatively low soil moisture that normally favors lichen growth, was the extremely dense moss stand. The close proximity to the Prudhoe Bay coastline (ca. 75 m), however, does not permit the exclusion of direct marine effects, which are no doubt responsible for the barrenness of nearby plot IV. The presence of lichens in high moisture sites with low moss biomass (plot IV), and the absence of lichens in a site with favorably low substrate moisture but a dense moss stand (plot V), lead to the conclusion that, at least in certain. sites, competition for space with bryophytes may be a limiting factor for lichen growth. Such competition was also observed in the case of adjacent high-center polygons in “Current address: School of Public Health, Harvard University, Cambridge, Massachusetts 03128 **Current address: Ohio Department of Natural Resources, Columbus, Ohio 43224 214 70°25' 149°00' 148°40' 148°20' Fig. 1. Location of the eight study plots at Prudhoe Bay. 215 Table 1 Prudhoe Bay Standing Crop data and plot description Ave. Standing Crop (g m2) % Total Standing Crop No. of Depth of Humus Soil Runoff Lichen Vascular Vascular % Soil Thaw* Layer Conductivity ** Soil Runoff Conductivity Tine) Plot*** Species Lichen Mosses Plants Lichens Mosses Plants Moisture (cm) (cm) (uzmho cm pH pH (umho cm!) | (0) 0.0 926.2 212.9 0.0 81.3 18.7 104 D=19.9 8.0 779 7A 7-5 374 T=33.3 Wl 4 3.9 314.0 254.1 0.7 54.9 44.4 80 D=22.3 5.2 362 70 66 409 T=31.5 Hl 10 55:3 95.3 204.9 15.6 26.8 57.6 19 D=40.8 iler/ 405 7.6 a 174 T=51.6 IV 11 44.1 281.7 247.1 Tad. 49.2 43.1 108 D=116 46 390 66 7.8 143 T=21.4 Vv (0) 0.0 1572.8 171.7 0.0 90.2 9.8 37 21.9 444 Te 7.8 373 vi 1 (crustose) 0.0 14.9 24 43.5 1.1 2140 TH 7/833 373 vil 14 83.1 27.5 470.0 14.3 47 81.0 26 D=33.1 1 270 7.1 7.1 222 T=46.8 Vill 8 54.6 461.3 251.8 7.1 60.1 32.8 52 D=156 4.3 421 7.6 7.1 222 T=35.5 * As of 7/13/72. D = depressions, T = tussocks 5:1 dilution (deionized water), 18-19 hrs. later filtered through No. 120 soil sieve Plot | — wet meadow in old lake bottom; (T10N, R14E, Section 4) Plot Il — edge of ridge around old lake bed; moist meadow; (T10N, R14E, Section 4) Plot IIl — top of ‘Fox Ridge” W of pingo; very dry, sandy soil; elev. 15 m (T11N, R14E, Section 33) Plot 1V — 100 m N of drill pad F; wet meadow; low-center polygons and many tussocks present (T11N, R13E, Section 2) Plot V — near Prudhoe Bay docks, 75 m from coast; moist meadow, dense moss cover (T11N, R15E, Section 16) Plot VI — (5 x 5 m) near Prudhoe Bay docks, 39 m E of plot V; very dry, barren high-center polygons; high salinity; crustose lichen cover (not weighed) more than 50% (T11N, R15E, Section 16) Plot VII — S flank of Michele pingo, heavy vascular cover; very dry, sandy soil; elev. = 14m (T11N, R13E, Section 5) Plot VIII — (5 x 5m) on stream terrace 0.7 km SW of Michele pingo; well drained, grassy area (T11N, R13E, Section 5) U.S. Tundra Biome site 4 at Barrow, which had nearly identical moisture contents but highly divergent lichen standing crops that were inversely related to moss biomass. Several other abiotic parameters showed a correlation with lichen biomass, although these are interpreted as being secondary reflections of soil moisture. For example, somewhat higher lichen standing crops were observed on sites with a greater depth of thaw and on sites with a thinner humus layer. However, this was prob- ably a ramification of the fact that dry sites generally had greater depth to permafrost and also less vascular plant and bryophyte cover, the latter of which would be responsible for thinner humus layers. The pH and conductivity of soil and runoff water did not appear to have an effect on the differential distribution of plants, as there was little variation among the samples. The only exception to this was the high salinity of plot VI. On that site a sterile white crustose lichen covered more than 50% of the surface area, while mosses were completely absent, and vascular plants were present only as isolated shoots. The sparsity of plant life in plot VI is not surprising in view of the well-known fact that most terrestrial plants are intolerant of high salt concentrations. Acknowledgments These studies were supported by a National Science Foundation grant to Ohio State Univer- sity, and logistics at Prudhoe were provided through the Prudhoe Bay Environmental Sub- committee support at the Tundra Biome Center, University of Alaska. SOILS The physical and chemical characteristics of cold regions soils are most stronaly controlled by their association with the micro (and macro) foposequence or relief form. In recognition of this the areas depicted on ths map represent distinctive soils—geomorphc unts. The numencal code appearing in each unit attempts to recognize: |. the Principal sod types in a combination of | o3 digits. A single dit indicates that greater than 75% of the area is occupied by the sail type designated; a !wo-digit combina- ton indicates more than 50% of the unit s occuped by the first soll type with the second soil type accounting for most of the remander A three- digt combination indicates a codominance of the soil lypes indicated; 2. the principal landform class reflects both surface pattern and relief contrast; 3, the texture of the thawed mineral soil, either at the surfoce or immediately below the organic soil horizon; 4. the slope class. The coding scheme as outlined does not attempt fo recognize all possible or actual variations which may occur within a map unit; rather those whch are the really significant, easily recognized dominants. The number and number cornbinations used in the code are explaned below. 71m APPROXIMATION DESIGNATION APPROXIMATE CONVENTIONAL EQUIVALENT RELIEF ELEMENT. CHARACTERISTICS kK. R. EVERETT Institute of Pol VEGETATION At Prudhoe Bay the vegetation and geomorphic feaiures are intimately interre- lated ond both are represented on ths map by a formula of symbols. Each formula represents the vegetation and geomorphe features in a particular map unit. The numbers in the formula indicate the vegetation types. On polygonal ground the veqe- tation types are sequenced in 2or 3 groups of microsites separated by semicolons (;). The first group is the vegetation on the polygon centers; the second, vegetation on the rims; and the third, vegetation in the polygon troughs. A dash indicates the absence of group or microsite category. The symbol of the most abundant vegetation type is underlined. The letters preceding the numbers in the formula indicate the geornorphic features of each map unit: P— polygonal ground S- streams and stream margns Fit or beni sloping terrain; L- lakes and ponds Ice-wedges are |ll-defined H- pingos R- small ridges and hills Often subscript is used to further define the geomorphic feature F- flat polygons B- river bluffs. L- low centered polygons f - frost bails H- high centered polygons 1— thermokarst pits M- mixed polygons 1 — reticulate-ridged flats D ord indicates either heavy or light disturbance respectively, the nature of whch may be futher defined by o sul sige |- organic or inorganic litter fram road construction; g- gravel, equipment tracks, and/or thick dust from rood, ‘and 1-impounded areas. The disturbance symbols may stand alone or follow the vegetation numbers ES CHARACTERISTIC SPECIES CHARACTERISTIC MICROSITE MOST COMMON TyPES STREAM. RIVER, AND LAKE MARGINS: all A xe DISTURBED AREAS. 2 Alaska D. WALKER AND P. J. WEBBER Institute of Arctic and Alpine Rowarch University of Colorado PREPARED IN DECEMBER 1973 § Ohio State Uni PRODUCED FROM AN UNCONTROLLED MOSAIC eee as aii * hg bpiy ral ah