Abstract: Based on the investigation of phytoplankton and water body nutrient concentrations in the Lihu Bay of Taihu Lake in January 2010 and by using GIS technique, this paper analyzed the species composition, dominant species, abundance, spatial distribution, and diversity of the phytoplankton in the Bay in winter. A total of 27 genera of 7 phylums were identified, among which, Chlorophyta (12 species), Bacillariophyta (7 species), and Cryptomonas (3 species) occupied 44.44%, 25.93%, and 11.11% of the total, respectively. The dominant species were Cryptomonas erosa, C. ovata, Chroomonas acuta,and Microcystis aeruginisa. The Shannon diversity index (H) was 1.1, and the Pielou evenness (J) was 0.34 on average. The phytoplankton had a density of 1099.6×10⁴ ind·L^-1, in which, Cryptomonas dominated the spatial distribution of the phytoplankton. The highest phytoplankton abundance was found in the zone covering from Baojie Bridge to Xidi Lake, and the lowest value was in the north of the Xidi Lake. As compared with the winter in 2007, the phytoplankton abundance in winter 2010 increased remarkably, and the dominant species shifted from Chlorophyta to Cryptomonas. Further analyses revealed that water body phosphorus was the limiting factor of phytoplankton growth, and the variation of water body nitrogen/phosphorus ratio was the main reason for the increase of the phytoplankton in winter.

Key words: Xiao Xing’an Mountains, LANDIS Pro 7.0 model, climate change, broadleaved tree species, aboveground carbon sequestration rate (ACSR).