Quantitative Characteristics Primary Analysis On Slope Vegetation In Huanfuchuan Watershed

Huangfuchuan is the first tributary of the middle reaches of the Yellow River, originated from the transitional zone between the Ordos Plateau and the Loess Plateau , inflowed the Yellow River in Shanxi Province. The total length of Huangfuchuan is 120 km and drainage area is 3240 km~2, the main part of Basin in the Zhungeer Region. This paper selected the part as study area. The succession of plant communities were studied by using quantitative methods, including classification and ordination, species diversity, interspecific association and correlation, and niche breadth and overlap. The types, structure, ecological relationships between species and communities in the succession procedure were analyzed in details.98 samples were divided into 9associations and 2Cluster by TWINSPAN, 7 community types by DCCA, each of them has their own characteristics. The result of DCCA ordination showed that different plant communities and their distributing area varied along the environmental gradients in the ordination graph. The first axis of DCCA soil denoted the soil nutrients, slope, vegetation cover, gradient and the second axis of DCCA denoted change of altitude and aspect. The result of DCCA 36 species can be used to divided into four ecological groups. From A→D, with the of the restoration succession, gradually reduce the annual and biennial herbs, perennial herbs, small shrubs and small semi-bush plants gradually increaseBy using of the richness, diversity and evenness indices, combined with TWINSPAN and DCCA techniques, species diversity and diversification mechanism were studied. Different stages of succession have a certain degree differences of species richness, diversity evenness indices. Environmental factors have a certain degree of impact on these indices change.The main dominant species of niche breadths and overlaps were measured using a series of indices proposed by Levins, Shannon-Wiener, analysed niche group of ecological significance .The results indicated the niche breadth of annual herbs eg. Setaria viridis,Salsola collina, Artemisia scoparias gradually decreased in the process succession, the niche breadth of Stipa bungeana, Stipa breviflora, Leymus chinensis gradually increased. The results indicated Stipa bungeana, Stipa breviflora, Leymus chinensis have strong capacity utilization of resources in the late stages of recovery.x~2 test, Jacccard indices and Ochiai indices were used to analyze the interspecific association of 19 dominant species of community. Pearson's correlation coefficient and Spearman's rank correlation coefficient were also applied to calculate correlations between species. In this region, negative correlations between groups indicate that the community Is in a dynamic state because of the disturb to the dominant species by many factors, most communities have not reached a steady state.