水沙过程变化下洞庭湖区的生态效应分析

Ecological Effects of the Variation Process of Water and Sediment of Dongting Lake

依据1951―2009年实测水文数据及多年实地考察资料,对比分析水沙过程变化对洞庭湖区生物群落及其生存环境的影响。结果表明:(1)水沙过程对生物群落及其生存环境具有多方面的生态支撑作用,水沙动态是洞庭湖生态系统的控制性变量;(2)泥沙的不断淤积,使各类植被洲滩发育与扩展,导致湖面缩小及调蓄功能减弱和天然捕捞鱼场减少;(3)各类植被洲滩相继出露和湖水位涨落交替过程,不但维系着东方田鼠种群数量及迁移的延续,还支撑着钉螺(血吸虫的中间宿主)的孳生和繁衍;(4)入湖水沙量的逐期减少,削弱了水域环境的净化能力,"四大家鱼"捕捞产量递减、候鸟数量和种类减少、鱼类种群衰减,珍贵鱼类大幅度减少。

According to the measured hydrological data during 1951-2009 and field survey data,the contrast method is used to analyze the influence of the changes of water and sediment process on biological communities and eco-environment in the Dongting Lake.The results show that：1）The process of water and sediment acts as a wide range of ecologically supportive role on biological communities and eco-environment in the Dongting Lake,and the process of water and sediment is a controlling variable for the ecosystem;2）The development and expansion of varied vegetation marshland are promoted by continual siltation,which may lead to reducing the water area,weakening the regulation function of the lake and reducing the natural fishing grounds;3）The continuous emerging of all kinds of vegetation marshland and the fluctuation of water level not only can sustain the continuity of population and migration of microtus fortis,but also support the propagation and multiplication of oncomclania snail＇s（intermediate host of schistosome）;4）The decrease of the amount of flow and sediment of the lake weakens the water purification capacities,reduces the capture production of the four major Chinese carps,reduces the quantity and varieties of migratory birds,decays the fish stocks,and substantially reduces the rare fish species.