Browsing Journal of Range Management, Volume 49, Number 3 (May 1996) by Subjects
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Effect of breed on botanical composition of cattle diets on Chihuahuan desert rangeFecal microhistology was used to estimate botanical composition of samples taken from Hereford (N = 11), Angus (N = 11) and Brangus (N = 37) 3 to 5 year-old cows in 3 seasons (October, 1991 and January and July, 1992) and from Hereford (N = 10), Angus (N = 9) and Brangus (N = 34) calves in October. Breed differences in botanical composition of diets and relationships between dam and offspring botanical composition of diets were examined. Breed differences were observed for cows in all 3 seasons and for calves in October. Brangus cows showed greater preference (P < 0.05) for Sporobolus than Hereford cows in October, January, and July. Brangus cows also showed greater preference for Sporobolus than Angus cows in January and July. Brangus and Angus calves showed greater preference for Sporobolus than Hereford calves in October (P < 0.05). Brangus cows had a stronger preference for Yucca and total shrubs in January than either Hereford or Angus cows. Hereford cows and calves had stronger preference for Aristida than either Angus or Brangus in October (P < 0.05). Regression of October calf botanical components on dam botanical components indicated significant relationships for only 2 genera, Aristida (P < 0.01) and Sporobolus (P< 0.06). These data suggest that genetic composition of the animal is an important factor determining utilization of key plant species on Chihuahuan desrt ranges.
Shrub-grassland small mammal and vegetation responses to rest from grazingBetween 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 macro-habitat 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.