西凉湖水生植物多样性研究

研究了江汉湖群西凉湖水生植物多样性的现状及其变化 ,讨论了西凉湖水生植物多样性丧失的原因和保护的途径。主要结果是 :( 1 )西凉湖现有水生植物 3 2科 5 6属 77种 ,优势种类为微齿眼子菜、密齿苦草、轮叶黑藻、菹草、野菱、双角菱、金鱼藻、凤眼莲和菰等。 ( 2 )西凉湖现有水生植物群落类型 1 3个 ,全湖水生植被覆盖率约为 61 %,平均生物量为 1 4 70 .5 g/m2 。 ( 3 )物种多样性指数最高的群落是“凤眼莲 +野菱 +双角菱群丛”(D =0 .8499,H =2 .975 8) ,其次为“菰—凤眼莲群丛”与“野菱 +双角菱群丛”(D =0 .840 1 ,H =2 .82 35 ;D =0 .83 2 4,H =2 .888) ,以微齿眼子菜群丛的多样性指数最低 (D =0 .2 2 81 ,H =0 .782 3 )。 ( 4 )二十年来 ,西凉湖水生植物多样性严重丧失 :植被覆盖率和全湖平均单位面积生物量分别下降了 3 8.80 %与 77.87%,先后有 8种水生植物 (水葱、荸荠、莲子草、乌菱、细果野菱、萍蓬草、睡莲、小眼子菜 )和 4个水生植物群落类型(荇菜群落、乌菱群落、马来眼子菜群落、穗花狐尾藻群落 )从西凉湖消失。 ( 5 )多样性丧失的原因是围网养殖、过度收获水草、耙捞蚌类螺类等人为干扰

Studies on the diversity of aquatic plants in Lake Xiliang

The diversity of aquatic plants and its changes in Lake Xiliang were studied. Both the mechanisms for the diversity loss and approaches to protect the diversity were also discussed. The main results are given as follows: (1)Seventy seven species distributed in Lake Xiliang in 2001,of which Potamogeton maackianus,Vallisneria denseserrulata,Hydrilla verticillata,P. crispus,Trapa incisa,T. bispinosa,Ceratophyllum demersum,Eichhornia crassipes and Zizania latifolia were dominant species. (2)The vegetation could be divided into 13 communities. In 2001 its coverage was about 61%,and its mean biomass in the whole lake was 1 470.5 g/m 2.(3)The community “ Eichhornia crassipes+Trapa incisa+T. bispinosa Ass”displayed the highest species diversity indices(D=0.849 9,H=2.975 8). Community“ Zizania latifolia-Eichhornia crassipes Ass”and“ Trapa incisa+T. bispinosa Ass” displayed the second highest indices(D=0.840 1,H=2.823 5;D=0.832 4,H=2.888). (4)During the last 20 years a heavy loss in aquatic plant diversity occurred in the lake: the vegetation coverage and biomass decreased by 38.80% and 77.87%,respectively. At the same time 8 aquatic plant species and 4 plant communities disappeared from the lake. (5)It could be concluded that it was violent human disturbance,such as over aquatics breed,over harvest of water grass,dragging for mussels and spiral shells,that led the diversity loss in the lake.