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.