关键词: 三峡水库, 开县, 消落带, 植物群落, 分类, 排序

Abstract: The water level of the Three-Gorge Reservoir(TGR) rose up to 156 m in the end of October 2006,which indicated that the Three-Gorge Project had begun its operation.In order to understand how the operation affects structure and composition of the plant community in the hydro-fluctuation area,an investigation of the plant communities in Kaixian County was carried out from July to September in 2008.The findings of the field survey were analyzed quantitatively with the TWINSPAN(two way indicator species analysis) and DCA(detrended correspondence analysis) methods for ordination.Results show that the TWINSPAN method sorted 170 quadrats in the study area into 19 types,among which Polygonum hydropiper,Xanthium mongolicum+Cynodon dactylon,X.sibiricum,Paspalum paspaeoides,and Imperata cylindrical were the most representative plant communities,revealing a distinct relationship between the plant communities and environmental gradients.Results of the DCA ordination by DCA indicated that submergence time,soil humidity and soil texture are the major factors affecting distribution and composition of plant communities in the area.

Key words: Three-Gorge Reservoir Area, Kaixian County, water level fluctuation zone, plant community, classification, ordination