Previous researchers have suggested that plant communities in the Chihuahuan Desert area respond quickly and positively to the removal of grazing pressure. In this study, Kelt and Valone determined whether this general conclusion was also true for summer and winter annual plant communities at an upper Chihuahuan Desert scrub site in Arizona which contained a 16 year old grazing exclosure. Thirty-four winter annual species were present inside and outside of the exclosure. The number of plants was greater inside of the exclosure and species composition varied between grazed and ungrazed sites. Forty-five summer annual species were present inside and outside of the exclosure and species composition also varied between grazed and ungrazed sites. Of 79 annual species recorded, only 2 species, 1 in each season, responded significantly to the removal of cattle: Stephanomeria exigua and Polygala tweedyi were more abundant on ungrazed plots. Three additional species, Eriastrum diffusum and Cryptantha micrantha in winter, and Mollugo cerviana (summer), approached statistical significance. The positive changes in species composition inside of the exclosures suggests that recovery may be occurring at a very slow rate and therefore, the authors feel that the conclusions of other researchers are too general and that site specific variables may determine how rapidly the beneficial effects of grazing removal occur.
Citations and enhanced abstracts for journals articles and documents focused on rangeland ecology and management. RSIS is a collaboration between Montana State University, University of Idaho, and University of Wyoming.