放牧条件下人工草地植物高度的异质性变化

Variations in the plant heights on the artificial grassland with cow grazing

通过对人工草地进行受控放牧实验,定量研究了草地主要植物的高度异质性受奶牛放牧率的影响,以及高度异质性的季节动态特征变化.研究结果表明:1)在以黑麦草等禾草占优势的人工草地上,每次放牧前后草地植物的高度都有不同程度的降低,而从草地植被总体看,放牧使草地植物高度的异质性提高;2)草地植物的高度异质性特征与家畜的放牧率密切相关,高放牧率条件下,由于奶牛对植物的采食选择性的降低,黑麦草与白三叶的高度异质性较低,相反在低放牧率条件下,它们的高度异质性较高;3)草地植物高度的异质性存在着季节动态变化规律.对任何一种植物,高度异质性在生长季中期达到最高,生长初期全都大于生长后期.本实验有关植物高度异质性的分析对于草地与放牧管理具有实用价值,即通过控制或调整草地高度异质性易变区对应的放牧率,可能实现对草地的均衡与最大利用.

By the controlled grazing experiment on the artificial grassland, the response characteristics and seasonal dynamics of plant heterogeneity to different grazing intensities with cows were quantitatively analyzed in this paper. The results showed that a. Although the plant heights were lower after cow grazing than that before grazing on the artificial grassland dominated by Lolium perenne and other grasses, as a whole, cow grazing could make an increase for vegetation height heterogeneity; b. There was a closed relationship between plant height heterogeneity and stocking rate. The plant height heterogeneity (H) of L. perenne and Trifolium repense became lower under the high stocking rates because of the diet selection of cows, and it became higher under the low stocking rates; c. A seasonal dynamics of plant height heterogeneity on grasslands was found in this experiment. There was a biggest peak value of plant height heterogeneity (H) during the middle of growth season, and for L. perenne, Dactylis glomerata and Tr.repense the plant height heterogeneity in early growth season was bigger than that in late growth season. Some valuable conclusions that the grassland vegetation utilization availability (evenness) will be improved by controlling the animal stocking rate could be applied to the practice for grassland and grazing management. 