1998年特大洪水后鄱阳湖自然保护区主要湖泊水生植被的恢复

鄱阳湖自然保护区的湖泊是相对独立于鄱阳湖主体湖的一个区域，是国际重要湿地。1998年的特大洪水导致湖泊中水生植物的地上部分大量毁灭。通过1999年和2001年的植被调查，并与历史资料比较，探讨了特大洪水干扰后的植被恢复动态。结果表明，1999年湖泊水生植物的种类和生物量均低于干扰前的水平；2001年物种种类已经恢复，苦草(Vallisneria spp．)和黑藻(Hydrialla verticillata)的生物量已超过干扰前的水平，但其它物种的生物量仍较低，尚处于恢复的初始阶段。据此推断，物种问恢复速度的差异主要与物种的无性繁殖方式有关。鄱阳湖自然保护区湖泊的植被恢复不同于温带和其它亚热带的湖泊，不经历轮藻(Chara spp．)作为先锋优势种的阶段，苦草和黑藻可以作为先锋种首先在湖泊中恢复。这可能与鄱阳湖作为通江湖泊其水位频繁波动、轮藻不易定居有关。研究显示，洪水导致的水生植物生物量下降和物种数目减少只是短期现象，湖泊水生植物能在几年内恢复到干扰前的水平。

The Restoration of Aquatic Vegetation in Lakes of Poyang Lake Nature Reserve after Catastrophic Flooding in 1998

The internationally important wetland,Poyang Lake Nature Reserve has several small lakes relatively independent from Poyang Lake.The aquatic plants in these lakes were destroyed by a catastrophic flooding occurred in 1998.The restoration of the aquatic vegetation following the high water stress was analysed by comparing the results of vegetation investigation in 1999 and 2001,as well as the historical data.The species number and the biomass in 1999 were lower than those before the flooding.However,species had restored by 2001,and the biomass of Vallisneria spp.and Hydrialla verticillata had exceeded that before the stress,but the biomass of the rest plants were still low.It was suggested the different restoration of plants were mainly related with their different vegetation propagation methods.The vegetation restoration in lakes of Poyang Lake Nature Reserve was different from that in temperate and other subtropical lakes in that no pioneer stage when Chara dominated occurred.The reason was that the frequent severe fluctuation of water levels in Poyang Lake affected the settlement of Chara.In the paper,we think that the decline of biomass of aquatic plants and the species number was just a short-term effect;and it will spend several years to restore the lake vegetation.