多重水位变动影响下的消落带地表昆虫扩散机制研究

Litter-layer insects are one of the essential elements of the draw-down zone ecosystem in Three Gorges Reservoir， and they play a very important role in maintaining the ecological health of the Three Gorges Reservoir region. Combined action of winter impounding and summer flooding threats the draw-down zone litter-layer insects seriously, but related researches are scarce, and the dispersal mechanism of litter-layer insects is still unknown. This study will take litter-layer insects in the main stream and important tributary of the Three Gorges Reservoir as object, and analyse their community structure and composition，and their distribution characteristics through investigations based on sweeping method and trapping method. The dispersal rules of the litter-layer insects will be studied based on marked recapture method. And the response mechanism of litter-layer insects to the multiple water level fluctuation will be revealed by redundancy analysis taking the water level fluctuations, habitat characteristics and human disturbances into consider, and the dispersal mechanism model of draw-down zone litter-layer insects is expected to be built primarily. Further investigations in other sections of the mainstream or other tributaries will be conducted as feedback to modify the dispersal mechanism model. Results of this study will be an improvement of the ecosystem knowledge of the draw-down zone, and an important supplement to the basic theory of the ecohydraulic engineering, and it will provide scientific basis in developing strategies for the reservoir operation and nearby landuse management.

地表昆虫是三峡水库消落带生态系统的组成要素之一，对维持库区生态系统健康有着重要作用。冬季蓄水和夏季洪水的共同作用将导致消落带地表昆虫群落发生频繁的迁移扩散运动，而目前相关研究甚少,该多重水位变动影响下的地表昆虫群扩散机制尚不清楚。本课题以三峡库区干流和重要支流消落带地表昆虫为研究对象，拟采用扫网法和陷阱法对其群落结构进行调查分析，以明确其时空动态分布特征；通过标志重捕法研究其迁移扩散规律；综合考虑水位变动、生境特征和人为干扰等影响因子，结合冗余分析法揭示其对多重水位变动的响应机制，初步构建地表昆虫扩散机制模型；并通过库区干流其他河段或其他重要支流扩展样地的补充调查，对地表昆虫扩散机制模型进行反馈修正。研究成果是对三峡水库消落带生态系统结构认知的完善，也是对生态水利工程基础理论研究的重要补充，可为优化水库运行及库周土地利用管理策略等提供科学依据。

地表昆虫是三峡水库消落带生态系统的组成要素之一，对维持库区生态系统健康有着重要作用。冬季蓄水和夏季洪水的共同作用将导致消落带地表昆虫群落发生频繁的迁移扩散运动，而相关研究甚少,该多重水位变动影响下的地表昆虫群扩散机制尚不清楚。. 本课题选题之处选择以消落带地表昆虫为研究对象探讨其在三峡水库多重水位变动影响下的扩散机制。在实践调查基础之上，课题组将研究对象进一步拓展到消落带地表节肢动物群落(包括地表昆虫)。研究采用扫网法和陷阱法对长江干流和梨香溪、渠溪、珍溪等重要支流河道消落带中的地表节肢动物群落展开了系统调查。共采集到地表节肢动物20.14万头，隶属昆虫纲、蛛形纲、倍足纲、唇足纲、弹尾纲、腹足纲、软甲纲等共6个纲、35目、213科；分析了消落带中地表节肢动物群落在不同时间、不同海拔高度及不同植物群落中的动态分布状况。研究表明消落带地表节肢动物个体数量月度动态变化情况在6月达到峰值，夏季洪水事件对个体数量有着直接影响。总体上，夏季地表节肢动物个体总数要高于春季；消落带地表节肢动物按科捕获量在8月达到峰值，6月次之，总体而言夏季地表节肢动物科数高于春季；结合陷阱法和标志重捕法，对多重水位变动影响下的消落带地表昆虫扩散影响机制进行了揭示。研究表明，植物群落分布和立地条件引起的生境改变是地表节肢动物在消落带中扩散的直接动力，而冬夏季水位变动则是引起扩散的根本原因。. 本项目研究成果是对三峡水库消落带生态系统结构认知的完善，也是对生态水利工程基础理论研究的重要补充，可为优化水库运行及库周土地利用管理策略等提供科学依据。