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Preliminary study on the index system of evaluation of the ecological quality over the alpine steppes along the Qinghai-Tibet Railway

The alpine steppes are mainly distributed in the vast valleys, lake basins, lakeshores, gentle slopes and alluvial-diluvial fans with elevation of 4 100-5 100 m a. s. 1. along the Qinghai-Tibet Railway, and the vegetation is dominated by Stipa purpurea. Based on the investigated results from the plots and the statistical and analyzed results, some indices, such as the vegetation coverage, species diversity, richness, number of species, coverage of the dominant species, organic matter content in soil and soil thickness over the alpine steppes, are selected as the evaluation indices to comprehensively and objectively appraise the quality of alpine the ecological environment over the alpine steppes and the quality of ecological regeneration projects along the Qinghai-Tibet Railway. In this method, the quantificational indices reflecting the ecological environment of vegetation are not only considered, but also the local characteristic indices of vegetation growth closely related to the ecological environment. These indices are closely related each other and are correlative, they are easy to be derived and applied, accord with the local conditions of the ecological environment quality, can be used to scientifically and objectively appraise the regional ecological environment quality, guide the ecological environmental regeneration, and guarantee the quality of the ecological regeneration projects along in the Qinghai-Tibet Railway construction.