• 责任者：Yu Ge (State Key Laboratory of Lake Sciences and Environment ; Nanjing Institute of Geography and Limnology ; Chinese Academy of Sciences ; Nanjing 210008 ; China) ; Liao Mengna
• 刊名：Quaternary Sciences
• 出版年：2013
• 卷期：33(6)
• 关键词：湖泊环境 ; lacustrine environment ; 生态系统 ; ecosystem ; 气候 ; climate ; 鄱阳湖 ; Poyang Lake
• 页码：p.1148-1159
• 图表：7 illus., 1 table, 65 refs.
• 分类号：1400
• issnNo：ISSN1001-7410
• isbnNo：CN11-2708/P

     Comparing to terrestrial ecosystem, lake ecosystem responding to global climate warming is more sensitive and vulnerable. Poyang Lake is the largest fresh-water lake in China. Although the lake is located in a catchment within the subtropical region （25 ° -30°N） , changes in the temperature are lower than the lake water volumes. The highest water level on the multiple annual records is 21.7m a. s. 1. with the lake area more than 3280km2 ,while the lowest water level is 5.9m a. s. 1. with the lake area lower than 146km2. The aquatic biomes are significantly affected by variations of the seasonal and interannual water changes. The lake levels have decreased and the lake bed has become drying recently, leading to numbers of water hazard events and aquatic ecosystem deterioration. However, it is not clear for the processes and mechanism of ecological hazards and ecosystem involution under the climate change.  Based on principles and structures of Lotka-Voherra dynamic model, this paper firstly built a competition system between phytoplankton algae and higher aquatic plant of the lake primary producers. Then a predator-prey system was constructed between top-level predator of fish and the primary producers in the lake ecosystem. Finally, based on relations between climate-lake water and the biomes,Lotka-Voherra competitive and/or predatory systems were established with delay functions and feedback controls. Four experiments of different periods, from the modern time to the past 1000 years respectively,were designed to perform the numerical simulations. Data,parameters and coefficients used in the simulations were based on our digitizing, compiling and analyzing the data that were published between 1988 and 2013 from Poyang Lake and the catchment.  The simulations showed that biomass variability of algae, aquatic-plant and fish biomes can arrive an equilibrium state in Exp. l, which reached a stable and cycling processes with their environmental carrying capacities, increase rates of the biomass, and competitive and/or predatory relations respectively in the lake ecosystem. Ecological effects of lake water can maintain the dynamic equilibrium in simulation of Exp.lI, represented by cycling circus from the bottom to the top biomes in the ecosystem. Applying the model for the past 1000 years,Exp.lll was controlled by climate-lake water changes. The result showed an asymmetrical process of biomass changes. The water increases lead to a slow rate of biomass changes while the water decreases make a fast rate of biomass changes, quantizing the water-controlled negative-feedback. In Exp. IV, the boundary conditions were controlled by precipitations in the Poyang catchment decreased 19%, the lake areas decreased 33% and water heights decreased 7%, leading to the lake biomass oscillating and declining during 600 - 700 months. When the extreme drought climate lasted more than 600 months,the biome growth stopped and the lake ecosystem froze. The result can be evidenced by sedimentary pollen data during Little Ice Age when psammophytes and xerophytes were dominant instead of aquatic and palustral plants. It is suggested that the lake ecosystem would be long-term oscillated and finally collapsed under a last-drought climate, because the changes in the boundary conditions significantly exceeded the capacity of the ecosystem.