鄱阳湖水位变化对獐觅食对策和生境选择的影响

as a species of the second class of state key protected wildlife, Chinese water deer has been widely distributed in the Poyang Lake. However, excessive hunting and habitat loss have resulted in a drastic decrease of this population. In recent years, the wetland landscape in Poyang Lake has changed intensively because the water deer was higher in summer and autumn and lower in winter and spring than before. How does the population of Chinese water deer in Poyang Lake adapt well to its habitat with notable change of water level? Which effect may be exerted on this population by the proposed dam construction across the northern end of Poyang Lake? starting from this problems, we proposed to discover its diet and food selection mechanism, and its foraging strategies under the condition of different water level, using microhistological analysis technology of feces and technology for determining plant nutrinent contents, energy and scondary compounds. Also, we propose to use infared automatic camera to record its foraging behavior. using 3S techonology, we porpose to study its habitat characteristic and habitat selection on the scale of landscape, range and mircohabitats, to find the key factors determining its habitat use. By simulating the correlation between water level and the sunmersion-emersion dynamics of grassland according to historical hydrologic data and remote sensing data, we plan to analysis the availability and distribution change of habitat and food resource for Chinese water deer when Poyang Lake is in different water level. Then, we can assess the potential impact of water control after the proposed dam constructed on the survival of Chinese water deer. We hope our research achivement will supply a good scientific data for the decision making on the conservation of the population and habitat of Chinese water deer.

獐是国家二级重点保护动物，曾广泛分布于鄱阳湖区，但是过度捕猎和栖息地丧失造成种群数量急剧下降，鄱阳湖区獐的数量仅剩1000只左右。近年来，鄱阳湖洪水期水位上升明显，枯水期水位持续偏低，湿地景观变化剧烈。獐如何适应鄱阳湖区环境的剧烈变化，规划中的鄱阳湖水利枢纽工程水位控制会对獐的生存产生怎样的影响？针对这些问题，本研究试图使用粪便显微组织分析法和营养成分分析技术，分析獐在不同季节的食物组成、食性选择及食性选择机制，并使用红外自动相机拍摄其觅食节律，以揭示不同水位条件下獐的觅食对策；从景观、区域和微生境尺度分析獐生境利用和生境选择的特点，揭示不同水位条件下影响獐生境选择的关键因子；进而，根据鄱阳湖水位时空变化规律，在GIS支持下拟合水位变化和洲滩淹露的关系，分析不同水位条件下獐生境和食物资源可获得性的变化，评估鄱阳湖水利枢纽工程对獐的潜在影响，为该种群的就地保护和生境管理提供科学的依据。

獐是国家二级重点保护动物，曾广泛分布于鄱阳湖区，但是过度捕猎和栖息地丧失造成种群数量急剧下降，据估计鄱阳湖区獐的数量仅剩1000只左右。近年来，鄱阳湖洪水期水位上升明显，枯水期水位持续偏低，湿地景观变化剧烈。为了研究獐如何适应鄱阳湖区环境的剧烈变化，本研究①使用粪便显微组织分析法，分析了獐在不同季节的食物组成和食性选择，结果表明，獐在鄱阳湖丰水期和枯水期食物组成存在明显的转变：丰水期，共取食植物22科55种，枯水期，獐共取食植物16科38种。丰水期和枯水期獐均以禾本科植物为主要食物，但枯水期取食频率高于丰水期；莎草科、菊科植物和柳叶菜科植物在两个阶段的取食频率相差不大；丰水期对蓼科植物、旋花科植物、茜草科植物取食频率高于枯水期，对十字花科植物、石竹科植物和蔷薇科植物取食频率低于枯水期。②鄱阳湖区獐的分布区较上个世纪90年代急剧萎缩，目前主要分布在鄱阳湖国家级自然保护区和南矶湿地国家级自然保护区，且种群数量急剧下降，在獐种群密度最高的吉山岛及其周边，目前种群数量仅14只左右，鄱阳湖区獐种群亟需拯救性保护。③獐随水位变化呈现出明显的生境转移，在丰水期，主要集中在吉山岛、吉牛山、枫林山等小岛；枯水期，獐扩散到草洲生境。丰水期的集中分布使鄱阳湖獐种群极易受到非法盗猎行为的沉重打击。④獐的生境利用受水位的显著影响，枯水期在草洲中栖息的獐随着水位的消退逐渐向湖中心地带转移，生境海拔显著下降，水位上升期獐的生境海拔逐渐升高，向陆地（主要是小岛）迁移。⑤卫星跟踪结果表明獐家域面积为361.6±447.1hm2，枯水期日活动距离（1214.3±756.2m）显著大于其丰水期日活动距离（1020.2±1114.7m）；獐在夜间和白天均有活动，且夜间活动量比白天活动量大。⑥红外相机在监测过程中仅记录到两只个体，拍摄率非常低。这表明红卫相机不适于研究珍稀物种的生态习性，种群密度低导致相机拍摄率低。本研究揭示了鄱阳湖水位变化对獐生境选择和食性的影响，为该种群的保护和生境管理提供了科学依据。