The Fluctuation Response of Populus euphratica Community to the Surface Overtopping Disturbance

The main purpose of this study is to examine the fluctuation characteristics of natural Populus euphratica community under surface overtopping artificial disturbance in the lower reaches of the Tarim River, China. According to the representative plot sampling method and grid sampling method, sampling sites were conducted and investigated. Selecting plant community structure, species diversity and dominant species as the characterized values of community fluctuations, the influence of surface overtopping disturbance on the P. euphratica community was studied. The main results are shown as follows. The species composition is changed a lot in P. euphratica community under surface-water overtopping disturbance. Species numbers and richness are increased in community after the influence of the disturbance. On the other hand, community structure transform simple into power to complex. And the vertical stratification tends to increase under the disturbance. After the disturbance, species diversity of P. euphratica community has great change. And both the species richness and species diversity are increased obviously while species evenness is appreciably decreased in P. euphratica community. Based on the data, the dominant species is selected from community. During the fluctuation process of community, species composition and community structure transform simple into complex significantly in P. euphratica community under disturbance. The amount of community (e.g. species richness) and species diversity are increased during the process of community change. It shows that the surface water supplement is an effective measure to make P. euphratica community positively fluctuate.