不同放牧强度下草地植物格局特征的变化

通过人工草地上的放牧试验，研究了奶牛放牧对草地植物黑麦草、鸡脚草和白三叶的种群空间分布格局类型、强度和规模的影响。试验结果表明：（1）放牧条件下草地植物总是倾向于集聚分布，而且放牧强度对植物集聚程度的作用存在差异；（2）总体上，植物平均拥挤的大小顺序为黑麦草〉鸡脚草〉白三叶，集聚参数的顺序与其相同，聚块指数则相反，占据优势的黑麦草更多地受到相邻的鸡脚草与白三叶的作用，体现了较高的拥挤效应，且随放牧强度的增加拥挤效应呈现加强的趋势；（3）家畜对植物格局规模影响明显，高放牧强度下黑麦草始终保持稳定的格局规模；轻度放牧强度下白三叶的格局规模变化很大，区组规模复杂。

Change of the Character of Plant Pattern under Different Grazing Intensities

The spatial distribution pattern of Lolium perenne,Trifolium repense and Dactylis glomerata was studied by conducting a controlling grazing experiment using cows in an artificial sward.The experimental results showed that(1) Three plant populations tended to impose aggregation distribution pattern under grazing conditions,and the grazing intensity also had effects on the aggregation intensity.(2) In general,x* index could be ranked as Lolium perenne > Dactylis glomerata > Trifolium repense,showed the same trend with x*,but for reverse of the x*/x.Lolium perenne was crowed by Trifolium repense and Dactylis glomerata,indicating a high crowing effect between plant species.Moreover,the effect of crowding increased with the grazing intensity.(3) Animals have considerable effects on the scale of plant distribution pattern. Lolium perenne could keep stable pattern scale under higher grazing intensities.On the contrast,the pattern scale of Trifolium repense was complex and showed patchy with difference size.Therefore,the plant distribution pattern varied with the grazing intensity in the sward.