不同放牧强度对红三叶、黑麦草草地植被和土壤养分的影响

对不同放牧强度下草地植物和土壤的变化规律进行了研究，结果表明：３年强度放牧使土壤的全氮含量和草地的组成和结构发生了较大的变化，使牧草产量下降１７．１％，草地主要种红三叶的重要值降低了３３．８％，均质度系数增加５１．１％，土壤的氮磷比升高１．３。轻度放牧使草地全氮含量降低０．０９６％，红三叶的均质度系数增加２１．０％。中度放牧并未使草地牧草产量和红三叶的重要值降低，同时使草地红三叶均质度系数保持在远低于１．０水平以下，但使土壤全氮含量下降０．０８５％。根据以上结果，中度放牧是保持草地持续高产的最好的放牧管理选择。

EFFECTS OF DIFFERENT GRAZING INTENSITIES ON THE VEGETATIVE COVER OF THE GRASSLAND OF RED CLOVER AND RYE GRASS AND ON SOIL NUTRIENT

In this paper, the laws of changes of plants and soil under different grazing intensities are studied. The results show as follows. High-intensity grazing applied over a period of three years induces comparatively big changes in the total nitrogen content of soil and in the composition and structure of the grassland. It causes the herbage yield to decrease by 17.1%,the importance value of the main species of the grassland, namely, red clover, to decrease by 33.8%, the coefficient of homogeneity of red clover to increase by 51.1%, and the nitrogen-phosphorus ratio of soil to increase by 1.3. Low-intensity grazing causes the total nitrogen content of soil to decrease by 0.096%, and the coefficient of homogeneity of red clover to increase by 21.0%. Moderate-intensity grazing does not cause the herbage yield and the importance value of red clover to decrease. Meantime it keeps the coefficient of homogeneity of red clover far below the 1.0 level but causes the total nitrogen content of soil to decrease by 0.085%. From the above results it can be concluded that moderate-intensity grazing is the best option of grazing management for keeping the sustained high production of the grassland.