基于生境变化的东洞庭湖典型食草雁类物种共存机制

In recent years, changes in the species co-occurrence of wintering waterbirds, especially the dominant species herbivorous geese, was seriously affected by the dramatic changes in the hydrological regime and the wetland vegetation patterns in the East Dongting Lake due to the global change and high-intensity of human disturbance (e.g. Three Gorges Project). However, studies on the driving mechanism of the co-occurrence of herbivorous geese in relation to their habitat changes are scares, especially in the East Dongting Lake. In this project, the co-occurrence of herbivorous geese with their habitat driving mechanism was studied in the East Dongting Lake. The contents of this project are as following: firstly, changes in the co-occurrence of herbivorous geese as well as their key influencing habitat factors were analyzed with historical and field survey data; secondly, the habitat driving mechanism of the co-occurrence of the herbivorous geese was examined by food niche and food availability analysis. Furthermore, the driving mechanism of the species co-occurrence was verified by simulating experiments. The objective of our study was to improve our understanding on the driving mechanism of the co-occurrence of herbivorous geese in relation to their habitat changes in the East Dongting Lake, and to promote the development of wetland management strategies for protecting wintering waterbirds in the East Dongting Lake as well as the middle Yangtze River floodplains.

近年来，受全球气候变化及人类干扰（如三峡工程运行）等多方面因素影响，洞庭湖水文情势及湿地植被格局急剧改变，进而严重威胁越冬候鸟尤其是食草雁类物种共存。但目前生境变化条件下，洞庭湖典型食草雁类物种共存机制尚不明确。本项目拟以长江流域食草雁类的主要越冬地之一—东洞庭湖为研究区，以三种典型食草雁类豆雁、小白额雁和白额雁为研究对象，基于长时间序列的野外调查，结合宏观尺度的生境因子变化分析，阐明雁类物种共存的变化规律及其关键生境影响因子；基于粪便的食性变化分析，同时结合宏观-微观尺度耦合的关键生境因子（食物可利用性）变化的分析，阐明生境变化下的典型食草雁类物种共存机制，并通过野外控制实验模拟对其机制进行验证。最后综合上述研究结果，系统揭示生境变化下的东洞庭湖典型食草雁类物种共存机制。以期为洞庭湖乃至长江流域冬候鸟的保护和湿地生态系统管理提供科学依据。

受气候变化及人类干扰（如三峡工程运行）等因素影响，洞庭湖水文情势及湿地植被格局急剧改变，进而严重威胁越冬候鸟尤其是食草雁类物种共存。本项目基于零模型、种间竞争和物种共存理论，通过历史数据收集、野外调查和控制实验模拟，结合生境因子分析和基于粪便的食性分析，掌握东洞庭湖典型食草雁类物种共存的变化规律及关键生境影响因子；深入揭示生境变化条件下东洞庭湖典型雁类的物种共存机制，并通过野外控制实验模拟对其机制进行验证。整合各项研究成果，最终系统揭示基于生境变化的东洞庭湖典型食草雁类物种共存机制。主要结果如下：（1）东洞庭湖典型食草雁类的主要分布区域为大小西湖、春风湖和丁字堤，其关键影响因子是退水时间和苔草NDVI；（2）东洞庭湖典型食草雁类在关键分布区域可以实现物种共存，但呈现显著的年际变化趋势；（3）东洞庭湖典型食草雁类物种共存的关键生境影响因子为退水时间和食物可利用性（苔草NDVI）；（4）在生境变化条件下，典型食草雁类通过生态位分离（包括：空间生态位—取食地分离、食性生态位—食性分离）实现物种共存，且小白额雁倾向于首先改变自身生态位。