Study On The Change Of Vegetation And Soil Nutrients Of Alpine Meadow Under Different Degradation Degrees In Eastern Qilian Mountains

Summary: Based on the investigation and analyses of properties of plant communities, five different representative grassland types according to the degradation and utilizing pattern of different degraded alpine meadow in Eastern Qilian Mountains of Gansu Province were selected to investigate their community diversities. They were non-degraded, lightly degraded, moderately degraded, heavily degraded, and extremely degraded grassland. The defference and variation features of soil nutrients in different grassland, at different soil layers were studied; the influencing factors were discussed as well. At the same time, the methods were given for ecological revegetation on alpine meadow. The main research results are as follows:1. The main life forms of plants were hemicryptophytes(60%～70%). With aggravation of grassland degree, life forms changed. From non-degraded to moderately degraded, the proportions of chamaephytes and geophytes decreased, hemicryptophytes and therophytes increased. From moderately degraded to extremely degraded, the proportions of geophytes and therophytes decreased, hemicryptophytes and chamaephytes increased. Species changes in terms of life forms showed as the gradual replacement between hemicryptophytes and geophytes under different degradation degrees.2. The transect of the area could be divided into three sections according to the dominant environmental factors which determined the characteristics of plant communities in each section and the community distribution varied among sections. In the lower section(2710～2930m), the moisture was the major constraint for community distribution, in the medium section(2930～2960m), the moisture and temperature became the dominant constraining factor,in the higher section(2960～3080m), the factor of temperature was the dominant.