历山山地草甸的生态关系

以山西历山的舜王坪草甸为研究地，运用TWINSPAN和DCA相结合的数量生态方法对9个群落进行划分，得到一个明显的随放牧强度变化的群落序列，即从群落Ⅲ、Ⅳ到群落Ⅴ、Ⅵ再到群落Ⅷ，分别为过牧阶段、中牧阶段和轻牧阶段。可见，利用TWINSPAN和DCA相结合可对不同放牧强度的群落进行划分和排序。从草甸的生态关系研究得出历山山地草甸退化的主要原因是人为干扰。运用DCCA排序法，综合样方和土壤环境因子信息，定量综合研究了放牧草甸与周围土壤环境的生态关系。DCCA第一轴也表现为放牧梯度，在过牧阶段的群落中，有机质和N的含量较高，土壤的退化滞后于植被资源的退化；而在轻牧阶段的群落中，营养元素含量较高。

Ecological Relationship in Lishan Mountain Meadow

The internal ecological relationship of vegetation community and the ecological relationship between vegetation and environment are always the key problems to ecologists. The methods of numerical classification and ordination are important ways to study the ecological relationship. The Shunwangping meadow of Lishan Reserve was the main study area, and 41 quandrats along with the increase of elevation were got using the system sampling methods. The natural characteristic of every quandrat was studied and the soil samples were analyzed. Using the quantitative ecological measure of combining TWINSPAN with DCA, we divided the 41 quadrats of Lishan Mountain Meadow into 9 communities. The first axis of DCA ordination denoted an obvious community sequence varying with grazing intensity. Community of III, IV were the overgrazing phase, while community of V, VI and community of VIII were the intermediate grazing and the under grazing phase respectively. The second axis of DCA ordination denoted the elevation change. The DCA ordination diagram of dominant species was similar to that of the vegetation community, which said that the distribution pattern of dominant species was accordant with the vegetation community and the distribution pattern of dominant species determined the vegetation distribution pattern. It was concluded that we could divide and ordinate the different grazing intensity communities using TWINSPAN and DCA. From the study of ecological relationship between the Meadow and its environment we got that the main degenerating cause of the meadow was human disturbing. Using DCCA ordination, we studied the ecological relation between vegetation and soil environment. The first axis of DCCA denoted the change of grazing intensity, which was the same to the DCA ordination. The content of organic matter and N were higher in the overgrazing communities than in others because the quantity of livestock in the overgrazing communities was higher than in other communities and its excreta was higher too. The overgrazing communities had a higher organic matter and N content, so the degeneration of soil lagged behind that of the vegetation resource. The content of nutrient elements was high in the under grazing communities, so the nutrient elements were important to the growth of plants.