The Artemisia frigida and Carex duriusscula were changed into perferred herbage,and the perferred index of Potentilla acaulis was significant increased when the stocking rate was heavy or overgrazing.

• 且星毛委陵菜成为主要的食物资源，占全部食物的80%25以上。这说明放牧率的增大和绵羊选择性的采食是草场植物种类组成发生变化的主要原因之一。