Botanic Food Preference of Allactaga sibirica Forster and Its Relationship with the Vegetation Conditions of Their Habitat Study on Morphological Formation Mechanism of Grazing Tolerance of Medicago falcata Effects of Different Grazing Systems for Dairy Cows on Soil Characteristics of Perennial Ryegrass/White Clover Sward Effects of Grazing Systems on the Community Characteristics of Alpine Steppe in Qinghai Lake Region A Study on Grazing Pattern and Grazing Internsity on Pasture at Hong Chi Ba The effect of different grazing systems on soil nutrient contents in dessert steppe