太湖流域湖荡湿地水生植物的分布特征

2018年在太湖流域内的87个湖荡湿地调查中共发现64种水生植物，隶属于33科51属.总体来看，太湖流域水生植物种类、数量以及覆盖面积与历史上比较呈下降趋势.根据流域上不同地理区域分区（东、西、南、北4个），分析太湖流域水生植物的分类和功能多样性，发现太湖流域四个区域的分类α多样性指数分别为4.33、5.58、5.01和3.46， β多样性指数分别为3.46、4.23、1.63和7.02，且北部和西部、北部和南部、东部和西部、东部和南部、西部和南部湖荡湿地的分类α多样性均有显著差异，同时太湖流域北部和东部、北部和西部、北部和南部、西部和南部湖荡湿地间的分类β多样性有显著差异.功能多样性方面，四个区域的β多样性指数分别为0.18、0.14、0.09、0.30，太湖流域各分区部分之间水生植物的功能β多样性均有显著差异.CCA结果表明环境变量对太湖流域湖荡水生植物组成的解释度为21.21%，水体总氮和总磷贡献最大，水体富营养化可能是影响太湖流域水生植物衰退的一个重要原因.

Distribution characteristics of aquatic plants in the watershed of Lake Taihu

In total, 64 aquatic plant species were found in the investigation of 87 lake wetlands within the watershed of Lake Taihu in 2018, which belonged to 51genera and 33families. In general, the species richness, abundance and coverage of aquatic plants all decreased in research area compared to the historical data. This paper studied the taxonomic diversity and functional diversity of aquatic plants in four different (eastern, western, southern and northern) geographical regions. Results showed that the diversity index α was respectively 4.33, 5.58, 5.01 and 3.46 and the diversity index β was 3.46, 4.23, 1.63 and 7.02, respectively. Significant differences in taxonomic diversity α of aquatic plants were found between northern and western, northern and southern, eastern and western, eastern and southern, western and southern parts of the watershed. Meanwhile, taxonomic diversity β of aquatic plants was also significantly different between northern and eastern, northern and western, northern and southern, western and southern parts of the watershed. With respect to the functional diversity, the diversity index β of aquatic plants among four regions was respectively 0.18, 0.14, 0.09 and 0.30, which were significantly different in pairwise comparison. CCA results showed that the degree of explanation to the composition of aquatic plants in the lake wetlands with the environment variables was 21.21%, and the eutrophication might be one of the major issues leading the decline of aquatic plants.