Effect of cattle grazing on range perennial grasses in the Mendoza plain, Argentina

Perennial grass responses to cattle grazing under a year-long continuous and four-pasture, one-herd grazing system, both with 20, 50 and 80% removal of grass annual production were evaluated from 1990–94. Live basal diameter, density and frequency of occurrence of each species were estimated on 1 m2quadrats placed along 30 m fixed line transects. Based on these data, total live basal cover, botanical composition by cattle selectivity category and diversity of grass species were derived. Data from the first 4 years of the study suggest that rotational grazing (80% removal) resulted in a significant decrease (p< 0•05) in total live basal cover, proportion and frequency of occurrence of the preferred grasses. Significant positive effects on those response variables were observed under rotation (50%) and continuous (20%) grazing.