地植物多样性间的关系

用显微技术法分别在放牧率为 1 .33,4 .0 0和 6.67只 / hm2下对内蒙古细毛羊的食性进行了研究。结果表明 ,随着放牧率的增大 ,草场的植物种类组成及其相对比例发生了明显的变化。由于不同牧草的可利用性不同 ,其食性选择也发生了明显的变化。在重牧条件下 ,原先为随意采食的冷蒿和厌食的寸草苔则升级为“喜食”的植物 ,星毛委陵菜的选择性指数也有较大提高 ;且星毛委陵菜成为主要的食物资源 ,占全部食物的 80 %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。食物的选择性主要与草地牧草的相对生物量、高度和频度显著相关 ;当草地植物多样性指数较高时 ,放牧绵羊的食物选择性较大。不同放牧率条件下 ,在以冷蒿和小禾草为主的退化草原上 ,草地植物多样性指数随放牧率的增大而显著降低 ,但食物多样性指数以放牧率 4 .0 0只 / hm2 的处理最高。

The dietary composition of fine wool sheep under different stocking rates and relationship between dietary diversity and plant diversity in Inner Mongolia steppe

The experiment was conducted at Inner Mongolia steppe.The vegetation was dominated by Leymus chinensis,Cleistogenes squarrosa,Artemisia frigada,Potentilla acaulis. The dietary composition of Inner Mongolia fine wool sheep were analysed by the micro|technique under different stocking rates of 1 33,4 00 and 6.67 sheep/hm 2 in August.The results showed that the dietary composition of grazing sheep was changed with the stocking rate increase because the herbage resource was limited.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.The selective ingestion of herbage has a positive correlation with herbage relative biomass,height and frequency.The plant diversity index of rangeland decreased with stocking rate increase.The dietary diversity index of grazing sheep was highest in the stocking rate of 4.00 sheep/hm 2.