Quantitative Classification and Ordination of Wetland Vegetations in Oxbows,Yangtze River

The classification and ordination of wetland vegetation in the Tian'ezhou Oxbows of the Yangtze River were studied using two-way indicator species analysis(TWINSPAN) and detrended correspondence analysis(DCA).A total of 234 samples collected from the wetland vegetation in the Tian'ezhou Oxbows were classified into 28 associations by TWINSPAN and the community characteristics of every association were described.The DCA ordination reflected the relationship between plant community type and the environmental gradient.The results showed that soil type and humidity were the main factors influencing the structure and distribution of wetland community.The TWINSPAN classification showed an explicit distribution scope in the DCA ordination plot,which better reflected the relationships between communities and environmental factors when combined with TWINSPAN quantitative classification.