Vegetal Change in the Absence of Livestock Grazing, Mountain Brush Zone, Utah
Journal of range management
Canopy cover of vegetrtion dominated by Cambel oak was determined in 1983 in adjacent canyons characterized by different grazing histories. Results were compared with data collected in 1935, and the methods replicated those used in the earlier study. Vegetal changes since 1935 in Red Butte Canyon where livestock grazing had been excluded since 1905 were small compared with those of Emigration Canyon where heavy graxing contfnued into the 1930's, but was gradually phased out and discontinued in
... nd discontinued in 1957. Large differences in vegetal cover between the 2 canyons reported in 1935 were mostly eiimhrated by 1983. Selective foraging by livestock is an important factor determining the composition of plant communities, and directly affects associated animal communities. Livestock select palatable forage and thereby give a growth advantage to less palatable, ungrazed plants. On many mule deer winter ranges in the Intermountain Region livestock grazing shifted presettlement, grassdominated communities to shrublands (Stewart 1941 , Reynolds 1960 , Christensen and Johnson 1964 , Hull and Hull 1974 , Harniss and Wright 1982. Mule deer herds responded to the increase in available winter forage and numbers significantly increased (Hancock 198 I).