MONTANA STATE This "cover" page added by the Internet Archive for formatting purposes s 58 1.529 Nl Ivrar 1994 /UG9-1999 VEGETATION MAP OF THE RARE PLANT COMMUNITY TYPES IN THE PRYOR MOUNTAINS AND PRYOR MOUNTAIN DESERT, CARBON COUNTY, MONTANA Prepared by: Peter Lesica Montana Natural Heritage Program 1515 E. 6th Ave. Helena, MT 59620 _MAY i 6 HM Prepared for: ,^... .,,..,. ^^.'^.'■.j .i-iiptfrr Miles City District Office -j; ^,^.'/-^ ^■''v-'^>>-''i*^H i s^ USDI Bureau of Land Management "' P.O. Box 94 0 MONTANA STATE UBRARy Miles City, Montana 59301 1515 East 6th Avenue Cap No. 201800 Helena, MT 59620-1800 Agreement No. 1 .22-E950-A1-0006; Task Order No. 20 January 1994 © 1994 Montana Natural Heritage Program This document should be cited as follows: TPsica P 1994. vegetation map of the rare plant community types in the Pryor Mountains and Pryor Mountain Desert Carbon CoSn?y Montana: Unpublished report for Miles City District, Bureau of Land Management. Montana Natural Heritage Program. Helena. 6 pp. plus 6 map sheets. Vegetation Map of Rare Plant Community Types in the Pryor Mountains and Pryor Mountain Desert, Carbon County, Montana Introduction The Pryor Mountains and adjacent desert lowlands of Carbon county, Montana support a diverse array of plant communities rLesic4 et al. 1992). Many of these are rare in Montana, and io^e a?e conildered^lobaliy rare (DeVelice and Vesica 1993) Plant communities are a good surrogate for overall ^^^^^H^j}:.^ diversity (Lesica 1993, Noss 1987, Ryti 1992 . Thus protecting high-guaiity examples of rare plant communities should protect populations of less conspicuous organisms such as invertebrates and fungi. The ability to locate critical plant communities on ?he landscape is essential to managing for biological diversity. DeVelice and Lesica (1993) sampled vegetation on lands administered by the Bureau of Land Management (BLM) ^^^.^he Pryor fountains and the desert areas south of the mountains in Montana. They used data from their survey to develop a classification system, and they provided descriptions of the plant communities in addition, they assigned global and state conservation ranks to these communities following Natural Heritage P^°g^^\"^^^^°^^ . ^^ (DeVelice and Lesica 1993). Fourteen of the 33 plant community types described were ranked as globally threatened or endangered (G1-G3) . The purpose of this study was to use the classification system developed by DeVelice and Lesica (1993) to map occurrences of rare plant communities on BLM lands in the Pryor Mountain study area. A secondary goal was to refine the classification system based on observations made in areas that were not sampled during the original study. The Study Area The Pryor Mountains and Pryor Mountain Desert are described in DeVelice and Lesica (1993), Lesica and Achuff (1992) and Knight et al. (1987). I mapped vegetation north of the Wyoming border and south of the Crow Indian Reservation. My study area was bounded on the east by the Big Horn River and on the west by the Clarks Fork of the Yellowstone River. Within this area, I confined my mapping to public lands administered by BLM. I did nSt attempt to map isolated parcels or areas with large private inholdings. Methods on June 11-17, 1993 I drove and hiked though the study area and mapped plant community types onto aerial photographs (1:29000) provided by BLM. I mapped ca. 35% the area east of Hwy •310 on the ground and ca. 2 0% west of Hwy 310 from the ground. The remaining area was mapped by extrapolation from the ground- truthed areas. Lines enclosing community types were transferred to 1:24000 USGS topographic maps after completion of field work. During field work I took notes on community composition when it deviated from descriptions provided by DeVelice and Lesica (1993) . Plant communities are often not discrete entities on the landscape, but rather blend into one another across ecotones of varying widths (Gleason 1926, Whitaker 1975). Lines separating community types were generally drawn along ecotones. Areas mapped as one community type may have inclusions of locally less common types. The minimum mapping unit was ca . 40 acres. Stands smaller than 40 acres were usually included within larger surrounding mapping units. Results A list of all community types reported by DeVelice and Lesica (1993) is provided below. Each entry is followed by the current Natural Heritage Program global and state ranks as well as any additional information acquired during 1993 field studies. Global and state ranks are defined as follows: ^ Gl or SI 1-5 occurrences or less than 2,000 acres in world or 9 state respectively. G2 or S2 6-20 occurrences or 2,000-10,000 acres in world or state respectively. G3 or S3 21-100 occurrences or 10,000-50,000 acres in world or state respectively. G4 or S4 Apparently secure in the world or state respectively G5 or S5 Demonstrably secure in the world or state respectively All community types with a global rank of 1-3 and/or a state rank of 1-2 were considered rare and were mapped. These types are shown in bold below. The number in front of each type is used to identify that type on the maps. Numbers of community types ranked Gl are in red; those ranked G2 are in green; and those ranked G3 are in black. 1. Ajbies lasiocarpa/ Arnica cordifolia c.t. G5/S5 2. Ajbies lasiocarpa/Clematis columbiana c.t. G4/S3 ^^ 3. Ajbies lasiocarpa/Ribes montigenum c.t. G5/S4 2 4. Abies lasiocarpa/Vaccinium scoparium c.t, G5/S5 5. Pinus flexilis/Festuca idahoensis c.t. G5/S5 6. Pinus flexilis/Juniperus communis c.t. G5/S4 7. Pseudotsuga menziesii/Agropyron spicatum c.t. This type has a very limited distribution in the Pryor Mountains and is probably best considered an ecotone between Artemisia nova/Agropyron spicatum c.t. and Pseudotsuga menziesii/Symphoricarpos oreophilus or Pinus flexilis/Juniperus communis c.t.s. 8. Pseudotsuga menziesii/Festuca idahoensis c.t. G5/S4. This type has a very limited distribution in the Pryor Mountains. 9. Pseudotsuga menziesii/Cercocarpus ledifolius c.t. 63/S3. This type has a very limited distribution in the Pryor Mountains. It is very similar to the Cercocarpus ledifolius /Agropyron spicatum habitat type described by Mueggler and Stewart (1980) . but is high enough to be at the lower limits of the tolerance of Pseudotsuga menziesii . Most stands have only juvenile Douglas fir present, but larger snags were observed in some stands. 10. Pseudotsuga menziesii/Symphoricarpos oreophilus c.t. G5/S3 11. Juniperus osteosperma/ Agropyron spicatum c.t. G47/S3. The two phases, Gutierrezia sarothrae and Artemisia nova, may warrant treatment as separate community types. 12. Juniperus osteosperma/ Artemisia tridentata c.t. G5/S2 13. Juniperus osteosperma /Cercocarpus ledifolius c.t. G3/S3. There appear to be two phases of this type: the Artemisia nova phase on deeper soils and the nearly barren Agropyron spicatum phase on shallow soils. 14. Juniperus scopulorum/ Artemisia nova c.t. G2/S2 15. Pinus flexilis/Juniperus osteosperma c.t. G27/S2 16. Pinus flexilis/Juniperus scopulorum c.t. G4/S3 17. Artemisia nova/Agropyron spicatum c.t. G5/S4 18. Artemisia pedatifida/ Agropyron spicatum c.t. G4/S2. This appears to be similar to the Artemisia pedatif ida/Sitanion hystrix c.t. reported for Wyoming. 19. Artemisia pedatif ida/ Agropyron smithii c.t. G4/S3. DeVelice and Lesica (1993) called this type Artemisia pedatifida/Atriplex nuttallii but a similar type under the former name has been described for Wyoming. There appear to be two phases of this type in the study area: Atriplex nuttallii phase in the eastern portion of the study area and the Agropyron smithii phase in the west part. 20. Artemisia tridentata/ Agropyron smithii c.t. G5/S5 21. Artemisia tridentata/ Agropyron spicatum c.t. G5/S5 22. Artemisia tridentata/ Atriplex confertifolia c.t. G4/S4 23. Sarcobatus vermiculatus/ Artemisia tridentata c.t. G4/S4. Typical examples of this community type occur in silty soil along stream terraces. However, there are stands dominated by Sarcobatus vermiculatus , Artemisia tridentata and Grayia spinosa on sandy calcareous soils east of Warren and just north of the Wyoming border. These unusual associations may warrant recognition. 24. Artemisia tridentata /Stipa comata c.t. G4/S4 25. Atriplex nuttallii /Artemisia spinescens c.t. Gl/Sl 26. Artemisia tridentata/ Atriplex nuttallii c.t. G37/S3? 27. Atriplex nuttallii /Monolepis nuttalliana c.t. G37/S2. This community occurs on barren bentonitic soils, usually in a mosaic of badlands community types. It is difficult to determine its relationships to similar community types in the intermountain region. 28. Potentilla fruticosa/Festuca idahoensis c.t. G4/S3 29. Sacrobatus vermiculatus /Atriplex nuttallii c.t. G4/S3. This community usually occurs in a mosaic of badlands community types. 30. Agropyron spicatum/ cushion plant c.t. G3/S3 31. Chrysothamnus nauseosus/Eriogonum brevicaule c.t. G2/S2 32. Festuca idahoensis /Agropyron caninum c.t. G4/S4 33. Carex rupestris/ Potentilla ovina c.t. G4/S3. This type has very limited distribution in the study area. Eleven Community types in the study area are ranked G3 , S2 or higher. These rare community types, their ranks and the estimated acreage for each in the study area are given below: 9. Pseudotsuga menziesii/Cercocarpus ledifolius c.t. G3/S3. 110 acres 12. Juniperus osteosperma/ Artemisia tridentata c.t. G5/S2 670 acres 13. Juniperus osteosperma /Cercocarpus ledifolius c.t. G3/S3. 1990 acres 14. Juniperus scopulorum/ Artemisia nova c.t. G2/S2 250 acres 15. Pinus flexilis /Juniperus osteosperma c.t. G2?/S2 2510 acres 18. Artemisia pedatifida/Agropyron spicatum c.t. G4/S1. 240 acres 25. Atriplex nuttallii/ Artemisia spinescens c.t. Gl/Sl 310 acres 26. Artemisia tridentata/ Atriplex nuttallii c.t. G37/S3? 3080 acres 27. Atriplex nuttallii /Monolepis nuttalliana c.t. G37/S2. 720 acres 30. Agropyron spicatum/ cushion plant c.t. G3/S3 3970 acres 31. Chrysothamnus nauseosus/Eriogonum brevicaule c.t. G2/S2 1540 acres BL. Badlands (mosaic of 19, 22, 26, 27) 2020 acres Discussion The presence of 11 rare community types makes the Pryor Mountains-Big Horn Basin area one of the most biologically unique areas in Montana. Many of these plant communities are currently known from nowhere else in the world (DeVelice and Lesica 1993). Threats to these communities have been discussed by DeVelice and Lesica (1993). The two high ranking (Gl or G2) plant communities that are currently most threatened are Atriplex nuttallii/ Artemisia spinescens and Chrysothamnus nauseosus/Eriogonum brevicaule. Both occupy very arid and edaphically harsh environments. Vegetation is sparse and not resistant to livestock grazing or invasion by exotics such as Halogeton glomeratus . Management options that minimize the impacts of livestock grazing in these areas should be considered. Literature Cited DeVelice, R. L. and P. Lesica. 1993. Plant community classification for vegetation on BLM lands, Pryor Mountains, Carbon County, Montana. Montana Natural Heritage Program, Helena. Gleason, H. A. 1926. The individualistic concept of the plant association. Bulletin of the Torrey Botanical Club 47: 21-33. Knight, D. H. , G. P. Jones, Y. Akashi, R. W. Myers. 1987. Vegetation ecology in the Bighorn Canyon National Recreation Area. Unpublished report submitted to the University of Wyoming- National Park Service Research Center. Lesica, P. 1993. Using plant community diversity in reserve design for pothole prairie on the Blackfeet Indian Reservation, Montana, USA. Biological Conservation 65: 69-75. Lesica, P. and P. L. Achuff. 1992. Distribution of vascular plant species of special concern and limited distribution in the Pryor Mountain Desert, Carbon County, Montana. Unpublished report to USDI Bureau of Land Management, Montana State Office, Billings, MT. Lesica, P., P. Achuff and R. L. DeVelice, 1992. Mapping the distribution of rare plants and plant communities for reserve design in the Pryor Mountain Desert, Montana. Northwest Environmental Journal 8: 180-181. Mueggler, W. F. and W. L. Stewart. 1980. Grassland and shrubland habitat types of western Montana. USDA General Technical Report INT-66, Ogden, UT. Noss, R. F. 1987. From plant communities to landscapes in conservation inventories: a look at The Nature Conservancy (USA) . Biological Conservation 41: 11-37. Ryti, R. 1992. Effect of the focal taxon on the selection of nature reserves. Ecological Applications 2: 404-410. Whitaker, R. H. 1975. Communities and ecosystems. Macmillan Publishing, New York. MONTANA STATE This "cover" page added by the Internet Archive for formatting purposes