Species richness inside and outside long-term exclosures

Abstract

Recent environmental literature contains claims that livestock grazing has caused reduction in species diversity on Western rangelands. Data of species richness (number of species) is presented from inside and outside 24 long-term exclosures in Montana, Utah, and Wyoming. For the average of all exclosures there was no difference between species richness inside and outside the exclosures. Overlap of species (those found both inside and outside of the exclosures) was high (69 to 72 percent), and the species found either inside only or outside only did not reveal any trend related to grazing or successional status. The areas inside and outside eight exclosures in Wyoming were sampled in 2 successive years. Growing season moisture was above normal the first year and far below normal the second. Species richness sampled was more than 40 percent lower in the second year than in the first. The rather small difference in species richness inside and outside all of the exclosures indicates that neither grazing nor lack of grazing has much long-term influence on species richness. However, growing season moisture can greatly influence how many species are encountered when sampling an area.

Parent Publication

• Seed and soil dynamics in shrubland ecosystems: proceedings; 2002 August 12-16; Laramie, WY

Citation

Laycock, W. A.; Bartos, D. L.; Klement, K. D. 2004. Species richness inside and outside long-term exclosures. In: Hild, Ann L.; Shaw, Nancy L.; Meyer, Susan E.; Booth, D. Terrance; McArthur, E. Durant, comps. Seed and soil dynamics in shrubland ecosystems: proceedings; 2002 August 12–16; Laramie, WY. Proc. RMRS-P-31. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. p.