植物群落结构特征对不同放牧强度的响应——以呼伦贝尔草原为例

以内蒙古呼伦贝尔典型草原克鲁伦河流域为研究对象,设置了轻度(LG)、中度(MG)和重度(HG)3种放牧强度样地,对不同放牧阶段草原的物种组成、土壤的化学性质进行分析。结果表明植物群落对放牧强度做出响应,放牧活动严重影响群落结构与功能特性。群落Shannon-Wiener 多样性指数和 Simpson指数在中牧强度下达到最大,随放牧强度的增加而减小。土壤全C、全N含量均随放牧强度的增加而增大,轻牧与中牧下土壤全P含量相似,均低于重牧,土壤C:N值在轻牧强度下达到最大。另外随放牧强度的增加,克氏针茅的N、P含量及N:P值有降低的趋势,C:N值有升高趋势。重牧强度下,群落优势种多根葱的C:N值明显低于克氏针茅。各放牧强度下优势种养分含量与土壤养分之间存在着不同程度的相关关系。

Responses of Plant Community Structure to Different Grazing Intensities——Taking Hulun Buir Grassland as an Example

Taking Kherlen River basin of Hulunbeir Grassland in northern China as the research object, we sampled soil and plants at three degrees of light, moderate and severe degradation respectively and analyzed the differences and relationships in species composition of grassland and soil chemical properties. The experimental results showed that plant communities would respond to different grazing intensity, and grazing activities seriously affected the community structure and functional characteristics. The Shannon-Wiener community diversity index and Simpson index became maximum in moderate grazing intensity, and decreased with the increase of grazing intensity. On the other hand, with the increase of grazing intensity, soil total carbon and total nitrogen content increased. The total phosphorus content of light and moderate grazing which were similar were lower than the total phosphorus content of heavy grazing, and the soil C:N value reached maximum in the light grazing intensity. With the increase of grazing intensity, the content of nitrogen, phosphorus and N:P of stipa grandis decreased, while the C:N value increased. Under the condition of heavy grazing intensity, the C:N value of allium, which is the dominant species of the community, was significantly lower than that of stipa. The correlation between the nutrient content of dominant species and soil nutrients was different under different grazing intensities.