Study On Succession Of Plant Communities On Abandoned Lands In The Northwest Shanxi, China

Jinbei abandoned land in low and middle hills is located at Ningwu, the northest part of Shanxi Privince. This paper selected the part as study area. The succession of plant communities were studied by using quangtitative 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.39 samples were divided into 13 associations by TWINSPAN, each of them has their own characteristics. The result of DCA ordination showed that different plant communities and their distributing area varied along the environmental gradients in the ordination graph. The first axis of DCA denoted gradient and the second axis of DCA denoted change of altitude and water-conditions. The ordination graph of preponderant species is very similar of community types, and the distribution of preponderant species determines the distribution pattern of plant communities to some extent.x~2 test with 2×2 contingency table and Ochiai indices were used to analyze the interspecific association of 17 dominant species of community. Pearson's correlation coefficient and Spearman's rank correlation coefficient were also applied to calculate correlations between species. The results indicted that species with positive association have similar biological characteristics and demand similar habitats, and the relationships among species-pairs are of significant difference in different communities and succession stages. The significant species-pairs from x~2 test is lower than that from the Spearman rank correlation test and Pearson test, and the Spearman rank correlation test is better than Pearson test.The niches breadths and overlaps of main dominant species were measured using a series of indices proposed by Levins, Shannon-Wiener and Petraitis. The results indicated that the greater the niche breadth of a species was, the stronger the ability of adaptation to environment and using resources...