| Steven S. Rosenstock |
| Author is research biologist, Arizona Fish and Game Department, 2221 W. Greenway Rd., Phoenix, AZ., 85203. At the time this study was conducted, he was independent consultant, dba Wingate Eco-Logic, P.O. Box 462, Fredonia, AZ, 86022. |
Abstract |
| Between 1989-1991, I studied the effects of livestock grazing on vegetation and small mammals in semiarid shrub-grassland habitats of south-central Utah. Responses were measured at 2 spatial habitat scales; patches and macrohabitats. Patch-scale data were obtained from 4 small (<1 ha) livestock exclosures and nearby grazed areas. Macrohabitat-scale data were collected at 4 actively grazed sites and 4 comparable, excellent condition sites, ungrazed for 30+ years. Ungrazed patch and macrohabitat sites had more surface litter, greater perennial grass cover, and taller perennial grass plants, but treatment response varied among sites. Small mammal responses were apparent only at the macrohabitat scale, where ungrazed sites had 50% greater species richness and 80% higher abundance. Small mammal reproductive activity and biomass were not affected by rest from grazing at either scale. Small mammal community composition varied greatly among sites and within treatments. This variability has important implications for ecological monitoring efforts involving these species. |
| Key Words: small mammals, grazing effects, scale, Colorado Plateau. |