感湖菱群落的数量特征

研究了湖北省感湖菱群落的水生植物种类组成、物种多样性指数、群落的垂直结构以及各种类的相对频度、相对生物量、优势度.结果表明:2002年,感湖菱群落共分布有水生植物20种,相对频度、相对生物量与优势度最高的种类均为野菱,其次是双角菱;该群落Shannon-Wiener物种多样性指数为2.302 5,单位面积生物量是2 183.8 g/m2 (鲜重);群落明显分为两层,浮叶植物层与沉水植物层,浮叶植物层的主体为野菱与双角菱,其优势度分别为21.59% 和18.22%,沉水植物层的主体是密齿苦草、金鱼藻和穗花狐尾藻,其优势度分别是11.46%、8.36%和8.15%;在水深1.0～3.5 m的范围内,菱群落物种多样性指数随水深的增加而减小,单位面积生物量则随水深的增加先升高后降低.

Study of the Quantitative Characteristics of Trapa Comm.in Lake Gan of Hubei Province, China

Plant species composition, species diversity index and vertical structure of Trapa Comm. in Lake Gan of Hubei Province, China were investigated. The relative frequency (RF), relative biomass (RB) and dominance value (DV) of each species in the Comm. were also studied in the paper. The main results are given as follows: twenty aquatic plant species were found in the Comm. in 2002, among which Trapa incisa and T. bispinosa displayed the highest and second highest RF, RB and DV respectively; with species diversity index 2.302 5 by Shannon-Wiener Index, the Comm. displayed biomass 2 183.8 g/m~2 (fresh weight); the Comm. could be divided into two layers: floating leaved hydrophyte layer and submerged hydrophyte layer; it was found that Trapa incisa and T. bispinosa are the dominant species of the floating layer (with dominance value 21.59% and 18.22% respectively) and of the submerged one, the dominant ones are Vallisneria denseserrulata, Ceratophyllum demersum and Myriophyllum spicatum (with dominance value 11.46%, 8.36% and 8.15% respectively); and species diversity index of the Comm. decreases with the increase of water-depth in the lake from 1.0 m to 3.5 m; however, biomass of the Comm. increases at first and then declines with the increase in water-depth.