Abstract: In September 2009, an investigation was made on the phytoplankton communities in 31 closed ponds of Xixi wetland, the first national wetland park in Hangzhou City, China. A total of 124 phytoplankton species were recorded, belonging to 61 genera of 7 phylums (Chlorophyta, Cyanophyta, Bacillariophyta, Cryptophyta, Euglenophyta, Pyrophyta, and Chrysophyta), among which, most species were of Chlorophyta, and fewer were of Cyanophyta and Cryptophyta but in higher abundance. Two-way indicator species analysis (TWINSPAN) and detrended correspondence
 (DCA) analysis showed that the species composition of the phytoplanktons in the 31 ponds could be classified into four groups, and all the groups were well separated on DCA axis, illustrating that there existed a distinct spatial differentiation of the phytoplankton communities in these ponds. Canonical correspondence analysis (CCA) was also applied to explore the relationships between the phytoplankton communities and the main environmental factors, and the results showed that NO₃-N, PO₄-P, SD, Chro, and COD_Mn were the main factors affecting the distribution and abundance of the phytoplankton communities.

Key words: Natural secondary forest, Snow/wind damage, Disaster