Abstract: An investigation was conducted on the community structure of phytoplankton in Changzhao Reservoir of Zhejiang Province in May, August, and November, 2010, and the diversity of the community species was analyzed by using Shannon diversity index, Simpson diversity index, Margalef diversity index, and Pielou evenness index. Meanwhile, the water quality of the Reservoir was evaluated based on the physicalchemical parameters. The identified phytoplankton species in the Reservoir belonged to 26 species or genera of 6 phyta, consisting of Cyanophyta (4 species or genera), Cryptophyta (1 genus), Pyrrophyta (1 genus), Bacillariophyta (9 species or genera), Chlorophyta (10 species or genera), and Xanthophyta (1 genus). The abundance of the phytoplankton ranged from 5.73×10⁵ to 7.73×10⁵ ind·L^-1, with an average of (6.71±0.81)×10⁵ ind·L^-1, and the biomass ranged from 0.73 to 1.03 mg·L^-1, with an average of (0.83±0.12) mg·L^-1. At all sampling sites, the species of Cyanophyta, Bacillariophyta, and Chlorophyta had high abundance in each season, whereas the species of Bacillariophyta, Chlorophyta, and Cyanophyta had the highest abundance in spring, summer, and autumn, respectively. Overall, the abundance and biomass of the phytoplankton community were higher at the inlet but lower at the outlet of the Reservoir. The diversity of the phytoplankton community in the Reservoir was lower, and the water was heavily polluted, with high concentrations of nitrogen and phosphorus and middlerich nutrition grade of eutrophication.

Key words: soil microbial biomass, soil enzyme activity, altitude, alpine-gorge region.