长湖水生植物多样性及其变化

研究了湖北省第三大湖泊长湖水生植物多样性的现状及其长期变化，并探讨了多样性丧失的机理及多样性恢复与保护的有效途径。主要结论：(1)长湖现有水生植物98种，多度最大的是微齿眼子菜(Potamogeton maackianus)、密齿苦草(Vallisneria denseserrulata)、野菱(Trapa incisa)、双角菱(T.bispinosa)、菹草(Potamogeton crispus)、紫萍(Spirodela polyrhiza)、穗花狐尾藻(Myriophyllum spicatum)、轮叶黑藻(Hydrilla verticillata)、满江红(Azolla imbricata)。(2)长湖现有水生植物群丛类型14个，群落物种多样性指数最高的是芡实 野菱 双角菱群丛(Euryale ferox Trapa incisa T.bispinosa Ass.)，其次为轮叶黑藻 密齿苦草|大茨藻群丛(Hydrilla verticillata Vallisneria denseserrulata Najas marioa Ass.)与竹叶眼子菜 穗花狐尾藻群丛(Potamogeton malaianus Myriophylhum spicatum Ass.)。(3)20年来，已有6种水生植物和7个水生植物群丛类型从长湖消失，植被覆盖率下降了54．85％，全湖平均单位面积生物量下降了69．78％。(4)多样性丧失的主要原因是过度养殖、过度打草和耙捞作业，以及由此导致的湖水透明度的大幅度下降。(5)多样性恢复的有效途径是政府部门的行政干预与经济支持。

Aquatic Plant Diversity and Its Changes in Changhu Lake of Hubei Province in China

Both the present state and long term changes of a qu atic plant diversity in Changhu Lake,the third largest lake of Hubei Province in China,were studied in the paper.The reasons for the diversity loss and effectiv e approaches to restore the degraded aquatic plant diversity and lake ecosystem were discussed.The main results are given as follows:(1) It was recorded that 98 aquatic plant species distributed in the lake in 2001,of which Potamogeton ma ackianus,Vallisneria denseserrulata,Trapa incisa,T bispinosa,Potamogeton crispu s,Spirodela polyrhiza,Myriophyllum spicatum,Hydrilla verticillata and Azolla imbricata displayed the highest abundance;(2) The aquatic vegetation in the l ake could be divided into 14 associations.It was found that Euryale ferox + Trapa incisa + T bispinosa Ass.possessed the highest species diversity indi ces(D=0 7224,H=2 3416),that Hydrilla verticillata + Vallisneria denseserru lata + Najas marina Ass.and Potamogeton malaianus + Myriophyllum spicatu m Ass.displayed the second and third highest indices,respectively (D=0 7202,H =2 0234;D=0 7186,H=1 9122);(3) In the last 20 years a heavy loss of the diver sity occurred:Six aquatic plant species and seven aquatic plant associations di sappeared from the lake.The vegetation coverage dwindled by 54 85% and the mean biomass per square meter in the whole lake decreased by 69 78%;(4) It could be concluded that it was violent human disturbance,such as overbreeding aquatics,e xcessive harvest of water grass,dragging for mussels and spiral shells,that led the diversity loss in the lake;(5) It was considered that the goal for restorati on of the degraded aquatic plant diversity and lake ecosystem could not be reali zed without sufficient participation of the government in fund and administratio n.