洪泛沼泽破碎化下水生无脊椎动物格局与食物网功能响应及机制

Connectivity is the key driving factor for the biodiversity and its food web function of marsh wetlands in floodplain. The hydrological and biogeochemical connectivity between rivers and marshes produce the dry and wet alternate habitats in floodplain, and regulate the biodiversity pattern. The wetland reclamation and dam construction directly lead to the marshes fragmentation and isolation to great extent. Aquatic invertebrate is an important part of the marsh food web, and it is the important food source of many waterfowl. Compared with other aquatic ecosystems, the research on structure and function of aquatic invertebrates in marsh has not yet been carried out systematically. However, it is critical to clarify the cascade relationship between habitat and biodiversity in the wetlands of floodplain. This program will select the marsh wetlands of Wusulijiang floodplain in the Sanjiang Plain, Northeast China, as the main study region. We will use the methods at different scales including field investigation, space-time substitution method, 13C 15N isotope mixing model and laboratory simulations to test and prove our hypotheses. We will firstly investigate the dynamics of aquatic invertebrate community composition and distribution pattern under different degrees of wetland fragement and isolation . Secondly, we will elucidate the aquatic invertebrate trophic level and food source structure changes, and clarify the food web structure of aquatic invertebrateand connectivity response to marsh fragmentation. In addition, based on the food web strucutre of aquatic invertebrates, the coupling relationship between biological connectivity, hydrological and biogeochemical connectivity in floodplains will also be revealed. This project will provide support for better understanding of the maintenance mechanisms of high biodiversity structure and food web function in wetlands.

河流-洪泛区沼泽间的水文和生物地球化学联系造就了洪泛沼泽干湿交替的生境，调控着洪泛沼泽生物多样性格局。湿地垦殖和堤坝建设等影响下，洪泛沼泽破碎化和孤立化严重。水生无脊椎动物是沼泽食物网的重要组成；但与其他水体系统相比，沼泽水生无脊椎动物结构和功能研究还没有系统开展；而这是阐明洪泛沼泽"生境-生物多样性格局-食物网功能"级联关系的关键。选择三江平原乌苏里江流域作为研究区，运用野外调查、时空替代方法和13C 15N混合模型等方法，明确沼泽破碎化下水生无脊椎动物组成、分布和功能类群差异，并揭示营养级和食物源结构变化，阐明水生无脊椎动物食物网格局的响应特征，剖析生境破碎化下水生无脊椎动物关键类群变化的级联效应，解析洪泛沼泽破碎化的面积、边缘和隔离效应，构建融合水生无脊椎动物格局和食物网功能的响应机制模型。为深入理解破碎化沼泽中生物、水文、生物地球化学连通间的耦合关系和沼泽食物网功能的维持机制提供支

本项目关注我国大部分洪泛区沼泽被人为垦殖或堤坝阻隔，呈现沼泽严重破碎化、水文联系阻断和沼泽孤立化的现实，按照“格局-功能-机制”的系统思维，以三江平原乌苏里江流域作为研究区，综合应用野外梯度调查、时空替代方法和13C、15N混合模型等方法，以水生无脊椎动物食物网格局与功能作为切入点，揭示洪泛沼泽对人类活动干扰下沼泽破碎化和孤立化的退化演替响应。项目按照预定的研究内容开展了工作，项目预定了研究目标全部实现。明确了人类垦殖和堤坝建设等强烈干扰下，洪泛沼泽湿地破碎化和孤立化对沼泽水生无脊椎动物组成、分布和功能类群的动态变化，揭示不同破碎化方式和孤立化强度下水生无脊椎动物营养级格局和食物碳源时空格局差异，阐明不同破碎化方式和强度沼泽区水生无脊椎动物的食物网复杂度和连通性，构建了洪泛区沼泽破碎化下融合水生无脊椎动物格局变化和食物网功能响应的生态演变概念模型，为深入理解洪泛沼泽“生境-生物多样性格局－生态系统结构－过程与功能”的级联关系提供支撑。