洞庭湖小白额雁越冬种群栖息地选择策略

The Lesser White-fronted Goose is one of the vulnerable bird species in the world, with its western population being on the edge of extinction for years, and the eastern population being heavily depends on the wintering ground in Dongting Lake. The operation of the Three Gorges Dam that leads to the river bed erosion and the significant ecological change between the Dongting Lake and Yangtze River, which imposed serve threats to the survival of the Lesser White-fronted Goose. Major ecological changes between the Dongting Lake and the Yangtze River include the earlier water level drop off that leads to fast development of Corex marshes in September. When the Lesser White-fronted Goose arrive Dongting Lake, and meadow becomes overgrow, which become not suitable for the birds to feed and wintering. To understand how Lesser White-fronted Goose adapt to the new environment, and select suitable habitat is one of the urgent scientific questions that guide the management of wintering habitat in Dongitng Lake. The proposed research project will build on the previous studies, design further field survey, to understand the spatial and temporal distribution of the Lesser White-fronted Goose in East Dongting Lake, in particular, its habitat selection strategies. Carry out experiment to explore how hydrological regime changes influence the growth of wetland plants which Lesser White-fronted Goose favored.The study will also design field test of the wintering habitat selection strategies. Results of the study will be important scientific references for the wintering habitat management.

小白额雁是全球易危物种，其西部种群基本处于灭绝边缘，而东部种群的越冬地仅仅局限于湖南省洞庭湖。三峡大坝运行带来的河床冲刷、江湖关系改变，严重威胁到小白额雁越冬种群的生存。主要体现在洞庭湖枯水期提前、洲滩出露、苔草草甸植物疯长，越冬小白额雁抵达时，基本不适合小白额雁取食。小白额雁如何适应食物资源和栖息环境改变下的生境，合理选择越冬生境，是洞庭湖国家级自然保护区小白额雁生境维护亟待解决的科学问题。 本研究将基于前期的研究成果，进一步调查、分析小白额雁越冬种群的时空分布规律，尤其是洞庭湖水情变化背景下的植被快速发育、食物资源短缺和栖息地景观改变下的生境选择对策。在此基础上，开展水情变化对小白额雁食源植物影响试验，选择东洞庭湖洲滩苔草草甸进行小白额雁生境选择的控制实验，验证小白额雁的生境选择策略，为小白额雁生境维护提供科学依据。

小白额雁是全球易危物种，其而东部种群的越冬地仅仅局限于湖南省洞庭湖。以小白额雁为代表的越冬雁类主要栖息于洞庭湖秋季退水后形成的草滩上。苔草属植物、荸荠属植物、看卖娘、蓼子草、虉草、毛茛属植物是为雁类的主要潜在食源植物。三峡运行导致洞庭湖提前退水的范围主要是27.42m（第273天）到23.42m（第322天）。三峡运行之后水位的变化的影响是加快了洲滩植被的发育。在这种背景下，当小白额雁迁徙到洞庭湖越冬时，其主要的食源植物苔草因为提前生长，不再适合取食。证实了传统的水文-植被-水鸟耦合机制发生变化，导致越冬雁类适宜生境面积和适宜取食食物减少，洞庭湖越冬雁类栖息地质量下降。应用同位素分析技术以及对越冬雁类卫星追踪数据建模，对比分析了小白额雁和豆雁在2015、2016两种不同退水节律下越冬季行为和生态位差异。发现在退水时间早栖息地质量较差的2016年两种雁类均通过增加飞行速度和飞行距离扩大了取食范围来满足能量需求，两种雁类的营养生态位宽度在2016年均有所减少。综合考虑处理效果与管理成本，在东洞庭湖枯水期提前，苔草疯长的情形发生时，建议采取火烧和刈割处理，在短期内为越冬初期小白额雁快速补充适宜食物。