不同放牧强度对植物及啮齿动物作用的研究

RESPONSES OF PLANT AND RODENTS TO DIFFERENT GRAZING INTENSITY

从栖息地结构特征决定啮齿动物群落组成的角度出发，通过分析不同放牧强度下植物地上部分生物量、植被组成、种的多样性以及不同放牧处理间相似性系数的变化，初步探讨了小哺乳动物对植被变化的反应，得到如下结论：１）在不同放牧强度下，植物地上部分生物量随放牧强度的增加而减少；植被组成中，优良牧草的比例随放牧强度的增加而降低，杂类草的比例随放牧强度的增加而升高。２）植物种的多样性指数随放牧强度的增加而升高。３）根田鼠种群密度随放牧强度的增加而逐渐降低。４）甘肃鼠兔种群受到重度、次重度放牧强度的严重影响而在这两个处理没有出现。其余处理中，随放牧强度的增加而逐渐减少，其平均密度与放牧强度呈显著的负相关（ｒ＝－０．９３２１，ｄｆ＝４，Ｐ＜０．０１）。５）高原鼢鼠的新土丘数在重度、次重度放牧处理有大幅度的增加，且明显高于次轻度和轻度放牧处理，此时的新土丘数与放牧强度呈显著的正相关（ｒ＝０．９３８３，ｄｆ＝４，Ｐ＜０．０１）。

The response of small mammals to vegetative changes was analyzed with different treatments and the following results were obtained .①Plant aboveground biomass, the percentage of grasses, sedges and Potentilla fruticosa shrub (leaves, tender stem) decrease with increase of stocking intensity and the percentage of herbs increase with increase of stocking intensity.②Vegetative species diversity raise with increase of stocking intensity.③Population density of root voles decline with increase of stocking intensity.④Populations of Gansu pika does not occur in heavily grazed, subheavily grazed treatments since they are influenced dramatically by grazing. Their average densities are significantly negative correlated with stocking intensity in the other treatment.⑤The number of new mounds digged by zokor at heavily grazed, subheavily grazed treatments significantly increases, and their size is larger than that of sublightly and lightly grazed treatments.