MONTANA STATE This "cover" page added by the Internet Archive for formatting purposes 583.123 Nllc^af ISS3 IllliiiiinlJiiiiililiJiiillllilllllllllJlllJIliJ,,,,,,,,,,,, 3 0864 0010 3950 5 U\1 5LtS.'^hf^T^^ STATE DOCUMENTS COLLECTION APR :/i 1998 ■ MONTANA STATE LIBRARY 1515 E. 6th AVE. HELENA, MONTANA 59S20 EFFECTS OF GRAZING ON ARABIS FECUNDA 1993 Progress Report Peter Lesica 929 Locust Missoula, MT 59802 and Montana Natural Heritage Program State Library 1515 E. 6th Avenue Helena, MT 59620 Prepared for: Bureau of Land Management Butte District P.O. Box 3388 Butte, MT 59702-3388 Agreement No. E950-A1-0006, No. 22 r \^\^fVi \^ L. I U iiH November 1993 INTRODUCTION Arabis fecunda Rollins is a rosette-forming perennial in the Mustard Family (Brassicaceae) . This recently described species (Rollins 1984) is endemic to highly calcareous, azonal soils in the foothills of the Sapphire Range in Ravalli County and in the Pioneer and Highland ranges of Beaverhead and Silver Bow counties, Montana (Lesica 1985, 1992, Schassberger 1988). Arabis fecunda generally occurs on steep, often eroding slopes with low vascular plant density. Arabis fecunda is a candidate for listing as a threatened or endangered species by the U.S. Fish and Wildlife Service (USDI-FWS 1990) and is considered threatened in Montana (Lesica and Shelly 1991) . Most sites at which Arabis fecunda occurs are grazed by livestock, but little is actually know about the effects of livestock grazing on this rare species. Recent studies have shown that A^ fecunda is more common on soil occupied by cryptogamic soil crust (Lesica and Shelly 1992) . These crusts are easily disturbed by livestock grazing; consequently, grazing may reduce A^ fecunda populations at these sites (Lesica and Shelly 1992) . Furthermore, A^ fecunda often occurs on steep slopes with unstable soil. Trampling by livestock could reduce the number of A_^ fecunda plants on these slopes. On the other hand, A_^ fecunda seems to require open soil for seedling establishment (Lesica and Shelly, submitted) and may be facilitated by disturbance associated with grazing. The purpose of this study is to determine the effects of livestock grazing on populations of Arabis fecunda. on the north side of the Pioneer Range. STUDY SITES Locations of the study sites are shown in Figure 1. Quartz Hill: From Dewey travel west on Hwy 43 ca. 0.3 miles and then turn south on gravel road (Beaverhead Forest Road #187) . Proceed ca. 1 mile up the road. Exclosure is on a steep hillside west of the road (TIS RlOW S8 NWl/4 of SEl/4) . Aspect: 95°, Slope: 40° Elevation: 5,900 ft. Thompson ' s Corner : From Dewey, travel west on Hwy 43 ca. 3.2 miles and then turn north on gravel road (Beaverhead National Forest Road #83). Continue ca. 0.2 miles and turn east on a small dirt road along the north side of the Big Hole River. Continue ca. 2 miles. Site is on the north side of the road on the west side of a small draw. TIS RlOW S5 hfWl/4 of.NWl/4. Aspect: 100°, Slope: 20°, Elevation: 5,600 ft. Dewey Cemetery: From Dewey travel west on Hwy 43 ca. 0.3 miles and then turn south on gravel road (Beaverhead Forest Road #187). Figoixe 1. Location of Quartz Hill (Q) , Thompson's Corner (T) and Dewey Cemetery (D) study sites. Proceed ca. 0.5 mile up the road to just past the cemetery. Pull in on the small two-track going east just past the cemetery. Site is on the hill to the south. Aspect: ca. 220 , Slope: 30 Elevation: 5,800 ft. METHODS .-- Field Methods The Quartz Hill and Thompson's Corner exclosures were established and read on 11 June 1991. They were read again on 7 June 1993. The Dewey . Cemetery exclosure was established and read on 7 June 1993. There is one exclosure plot and one control plot at each site. Each exclosure plot is 6 ft X 6 ft, marked at the four corners by metal stakes and completely covered by firm wire mesh. Control plots are placed near by the exclosure and are identical except they are uncovered. Each plot is divided into four equal subplots (3 X 3 ft) to facilitate counting. In each subplot estimate the basal cover of rock, moss- lichen, bare ground and vegetation, and estimate the canopy cover of grass, forbs and shrubs to the nearest 5%. In each subplot count the number of Arabis fecunda plants in each of three size classes: Seedling (S) : single rosette smaller that a penny Rosette (R) : single rosette larger than a penny or multiple rosettes Fruiting (F) : plants with flowers or fruits Data Analysis Changes in basal or vegetation cover between exclosure and control plots can be assessed by visual examination of the summary tables. There are no replicates of the treatments at any of the ^ sites; thus, statistical tests based on parametric distributions (e.g. t-test, analysis of variance) cannot be used. It is necessary to use counts (frequency) and contingency table analysis. The ratio of Arabis fecunda plants in year tto that in year t+a in the exclosure can be compared to the ratio from the control plot with a chi-square test. This test assumes that the observations are independent; i.e., the plants counted in year t+a cannot be the same as those counted in year t. Demographic monitoring studies from low-elevation sites indicate that 65% of cohorts have died after three years. Thus, the test cannot be considered valid unless comparing counts taken at least three years apart. Number of plants in each of the three size classes can also be compared using the same test. RESULTS AND DISCUSSION Exclosures at the Quartz Hill and Thompson's Corner sites were established in 1991; thus, a valid statistical analysis cannot be performed until 1994. Nonetheless, examination of the data is instructive. Grass cover increased more noticeably in the exclosure plots compared to the control plots. At Quartz Hill the number of A^ fecunda plants decreased in the exclosure but increased outside of it between 1991 and 1993 (Table 1) . The two ratios: 83/67 and 59/81 are significantly different (X-5.04, "g"=0.025) . At Thompson's Corner there were more A^ fecunda plants in both exclosure and control plots in 1993 compared to 1991, but the increase was much greater inside the exclosure (Table 2) The ratios 26/116 and 25/42 are significantly different (X^=8.91, "E"=0.003) . The statistical tests are invalid for reasons given above; however, it appears that the treatment had opposite effects at the two sites. LITERATURE CITED Lesica, P. 1985. Report on the conservation status of Arabis fecunda, a potential candidate species. Report to the U.S. Fish and Wildlife Service, Office of Endangered Species, Denver, CO. Lesica, P. 1992. Vascular and sensitive plant species inventory for the Highland Mountains, Deerlodge National Forest. Montana Natural Heritage Program, Helena. Lesica, P. and J. S. Shelly. 1991. Endangered, threatened and sensitive vascular plants of Montana. Montana Natural Heritage Program, Occasional Publication No. 1, Helena, Montana, USA. Lesica, P. and J. S. Shelly. 1992. The effects of cryptogamic soil crust on the population dynamics of Arabis fecunda (Brassicaceae) . American Midland Naturalist 128: 53-60. Lesica, P. and J- S. Shelly. Submitted. Demographic analysis of competitive effects of Centaurea maculosa on Arabis fecunda. Journal of Ecology. Rollins, R. C. 1984. Studies in the Cruciferae of western North America II. Contributions to the Gray Herbarium 214: 1-18. Schassberger , L. A. 1988. An update of the report on the conservation status of Arabis fecunda, a candidate threatened species. Report to the U.S. Fish and Wildlife Service, Office of Endangered Species, Denver, CO. USDI-Fish and Wildlife Service. 1990. Endangered and threatened wildlife and plants; review of plant taxa for listing as endangered or threatened species; notice of review. Federal Register 55 (35): 6184-6229. Table 1. Basal and canopy cover of ground and vegetation in exclosure and control plots at three study sites. Litter cover is combined with bare ground. QU, artz Hill Exclosure Control 1991 1993 1991 1993 Rock 0 13 0 10 83 1 8 8 14 1 Bare Ground — 73 — Moss/lichen — 2 Basal Veg. — 14 Grass 0 19 .4 Forbs 3 25 4 Shrubs 2 8 3 Thompson's Corner Exclosure 1991 19' Rock 48 50 Bare Ground 31 Moss/lichen 4 Basal Veg. 15 Grass 9 45 Forbs 8 26 Shrubs 0 0 Cont rol 1991 19! 34 36 53 3 9 8 11 8 23 2 2 Dewey Cemetery Exclosure 1993 Control 1991 1993 Rock Bare Ground Moss/lichen Basal Veg. Grass Forbs Shrubs 41 54 1 5 10 5 0 38 58 1 5 5 5 0 Table 2. Density of Arabis fecunda plants in three size classes in exclosure and control plots at study sites in 1991 and 1993. Size classes are seedling (S) , rosette (R) and fruiting (F) . 1991 1993 Quartz Hill Exclosure S R F Total 59 24 83 24 7 36 67 Control R F Total 55 4 59 21 46 81 1991 1993 Thompson's Corner Exclosure S R F Total 15 11 26 15 29 72 116 Control ; R F Total 15 10 25 2 15 25 42 Dewey Cemetery 1993 Exclosure S R F Total 0 11 23 34 Control S R F Total 0 15 22 37 Arabis fecunda Grazing Exclosure Study -: Site Date_ Examiner ( s ) Estimate basal cover (rock, bare ground, moss/lichen, basal vegetation) and canopy cover (grass, forbs, shrubs) to the nearest 5% (T=l%) in each 1/4-plot. Count number of A^ fecunda plants in each size class: seedling (S), rosette (R) and fruiting (F) . Exclosure Subplot Rock Moss Basl Bare Grss Forb Shrb S R F T Veg Grnd Total Control Subplot Rock Moss Basl Bare Grss Forb Shrb S R F T Veg Grnd Total Site Qu^y^fz^^Mugg, Examiner (s) 1^o£ SV[CO<^ Date 1} JlovoZ- 7/ Subplot L 5 Exclosure Rock Moss Basl Bare Grss Forb Shrb S R F T Veg Grnd _^_::i^^_i_A.^ ^L Jl :L ^ _^_j^i:lj^_o_^^_ - i & id _^ _rL ^L ^n _^ il. _o_ "J ^ I'l Subplot ( J Control Rock Moss Basl Bare Grss Forb Shrb S R F T Veg Grnd 6 ^ ~ - ^5 ^S <5 -21/2^ site Examiner (s) Date 7 juAA^'?3 Subplot Exclosure Rock Moss Basl Bare Grss Forb Shrb Veg Grnd UlL JL A. ^ M A JiL JJ3. JL A- A£ lo ^ ^ a _o _L ^ ^ ^ 1_ A. 13 0 a 3 5 Control Subplot Rock Moss^Basl Veg Bare Grss Grnd Jr'orD bnri 1 35. 3o r 5 r 5 43 5 s s — • n^ - 3 fo r S_ 55 5 s -^ 4 15 T 5 30 5 J? — o_ i_ jL ^ ^ J_ ^ .5 _^ ^ i£ ii o 5 5 § site 'ri\atM/}£,0U CcnAKJL^ Exaininer(s) ^^^ i 6 lA^^^^-^ Date // 'TuAy'^fL ^ I Subplot / 3 Exclosure Rock Moss Basl Bare Grss Forb Shrb Veg Grnd iil. ji_ ji_ _:^ Mi> M^ -Q_ 1^ Jl_ -H. Jl. ^ 5dD_ O ^b " - - i'lO 5- ID O ^ ^ 1 (. I 8 Subplot I Control Rock Moss Basl Bare Grss Forb Shrb S R F T Veg Grnd ^ jr_ _n_ ^i_ iilp tio, ^5 _^ S_ _J_ _4 ^ Jl- ::L ^L^ Sdo Szlo _±5_ - ^ 6 /f ^^_JZ__ii_fl.5:15^ " o 2- ^ Ho " ^ - Ms s-iD o -^13 site T\icnvy)vt^vv Ccru^^-s^^ Date Examiner (s) Lo^c!^ £4^^ 7 ru^^ 9 '^ Subplot 1- 3 Exclosure Rock Moss Basl Bare Grss Forb Shrb Veg Grnd _^ JE _i3 33 J5 _^ :^ ^ ^ JS_ 25, ^ha ^ -^ M -A Js. ^ Mo, sO^ _^ So s _is_ ^0. hS io J_ j_ Jo ^ a^ Z_ S_ J_ 1}I _^ ± ^ 1^ 3_ A i5 A3 Subplot 3 Control Rock Moss Basl Bare Grss Forb Shrb Veg Grnd ^ jr wl Jio Jo 20 j_ M JT io ^ iS. 1^ jr 2o_ ^ JO. A5 -A 22. jL ^b 5 5 ^0 15 20 _o_ ,V_ 5_ JL JP ^ JL J_ 13 2_ _!_ 7_ J/ site quoR-lz. l-lc^ Date 7 TUJ^^ l3 Examiner (s) r/p^c:^ SU^^ Exclosure Subplot Rock Moss Basl Bare Grss Forb Shrb Veg Grnd Ai :L A^ 11 M ^ 10 M. ^ Io_ _^ M. ^ lo_ 10 X' 5 SS 20 2S 0 2_ ^ Jl 2] ^ JL s. n HL ^ A^ }1 "I I S Id Control Subplot Rock Moss Basl Bare Grss Forb Shrb Veg Grnd s R F T / 'S T \o S3 10 10 0 ^ 3 /o IS 7. \t> r ID ^b ^ 2v S 3 7 /y ^^ 3 13 T 5 M ^ J± 0 (o 5 // 22 ^ \0 r ^ ^ ID /O 0 0 ^ // n MONTANA STATE This "cover" page added by the Internet Archive for formatting purposes