关键词: 新种, 文山无柱兰, 生物地理学意义, 滇东南

Abstract: In order to reveal the effects of human disturbance on aquatic plant diversity in freshwater lakes,the species and community diversity of aquatic plant,and their longterm changes in six freshwater lakes of DongtingPoyang District (Lake Bailian and Haikou under lightly disturbance,Changhu and Xiliang under heavy disturbance,Datong and Wushan under very heavy disturbance) were comparatively studied by means of Transect Sampling Method,Global Position System Technique (GPS) and Geographical Information System Technique(GIS).The main results are as follows:(1)It was found that Lake Bailian,Haikou,Changhu,Xiliang,Datong and Wushan contained 69,67,98,77,56,38 aquatic plant species and 14,14,14,13,6,0 associations,respectively in 2001.Their coverages reached to 100%,9618%,6532%,6118%,1060%,0% and mean biomass 2231?g/m2,2718?g/m2,1816?g/m2,1471?g/m2,256?g/m2,0?g/m2 (fresh weight),respectively.(2)As compared with the data obtaining from the surveys in 1980 to 1982,1,1,6,7,9 and 29 species,and 1,1,4,4,5 and 6 associations of aquatic plant disappeared from the six lakes respectively in the last twenty years.Their respective vegetation coverage decreased by 0%，382%，3285%，3780%，594% and 9100%.(3)According to the statistics of plant species,there appeared a gradient as follows:Lake Bailian，Haikou>Changhu，Xiliang>Datong，Wushan.Their different current situations clearly reflected that in the past twenty years thery had suffered from human disturbance in different degrees.(4)The main biological mechanism for the loss of aquatic plants is that human disturbance destroyed the rhizomes and the dormant kuds can't formed.

Key words: Aquatic plants