Preliminary study on community characteristics of Isoetes orientalis at different succession stages

Comparative analyses of species composition, community ecological quantitative characteristics, species diversity and propogation mode of Isoëtes orientalis H. Liu et Q. F. Wang communities at different succession stages were conducted by the method of space-replacing-time. The results show that at early succession stage, the community has the lowest diversity ( species richness, Shannon-Wiener index, Pielou evenness index and β diversity index) , and the abundance, coverage, important value and niche breadth of I. orientalis population are the highest, which makes I. orientalis the dominant species. At middle succession stage, the abundance, coverage, important value and niche breadth of I. orientalis population all decrease, while the community shows the highest species diversity, which makes the climax community of I, orientalis. At late succession stage, the abundance, coverage, important value and niche breadth of I. orientalis population fall to the lowest levels, and perennial herbs such as Miscanthus sinensis Anderss. and Zizania latifolia ( Griseb.) Turcz. ex Stapf become dominant species. Along with the succession process, the number of species adopting asexual/vegetative propogation increases and the main propogation strategy of the community changes from sexual propogation to asexual/vegetative propogation. It is suggested that in the process of succession, the changes of species composition, species diversity, propogation strategy of species and mesophytic habitat may be the major reason to decline of I. orientalis population.