长江流域淡水贝类分布模型与保护需求分析

DISTRIBUTION MODELS AND CONSERVATION REQUIREMENTS OF FRESHWATER MOLLUSCA IN THE YANGTZE RIVER BASIN

  • 摘要: 研究以长江流域淡水贝类三大分类群(前鳃亚纲、肺螺亚纲和双壳纲)为研究对象, 通过野外调查和文献资料分析获取贝类资料, 在提取不同尺度环境数据的基础上开展了各类群贝类的MaxEnt分布模型与保护需求研究。结果表明: (1)气候变量是决定三大分类群分布范围的重要因子, 其次为人类干扰因子。海拔和溯流距离是决定前鳃亚纲和双壳纲分布格局的重要变量, 而这两个变量对肺螺亚纲的影响微乎其微。(2)建立了累积种数-面积(长度)关系, 并据此推算出不同水域的最小保护需求, 其中干流岸线1181 km(占总长的18.7%), 支流岸线16960 km(占支流总长的8.7%), 阻隔湖泊6397 km2(占阻隔湖泊总面积的70.6%), 通江湖泊5609 km2(占通江湖泊总面积的86.3%)。(3)淡水贝类主要分布区在“三湖二干流”组成的生态系统网络, 即鄱阳湖、洞庭湖、太湖、中游干流和下游干流。进一步分析发现, 已建立的适宜淡水贝类的湿地保护区面积为2.1×104 km2, 河流保护长度为1885 km, 保护区面积不足且多呈斑块状分布, 与需要保护的潜在分布区重合度较低。相关结果有望为长江流域淡水贝类物种多样性保护和流域整体保护提供科学指导。

     

    Abstract: This study selected three taxonomy groups (Prosobranchia, Pulmonata and Bivalvia) of freshwater Mollusca as the conservation target to build MaxEnt distribution models and analyze relevant conservation requirements based on field investigations and literature collections of species data and environments. The results showed that: (1) Bioclimatic variables were the key groups of environments to explain the distribution variance of the three taxonomy groups. Human disturbance variables also played an important role. Elevation and upstream were the two important factors for distributions of Probsobranchia and Bivalvia, while weakly related to that of Pulmonata. (2) Cumulative species-area (length) relationships were established, according to which the minimum requirements of the length of mainstem and tributaries, the area of river-isolated and -connected lakes were 1181 km, 16960 km, 6397 km2, and 5609 km2, respectively. They accounted for 18.7%, 8.7%, 70.6%, and 86.3% of the total length of mainstem, the total length of tributaries, the total area of river-isolated lakes and the total area of river-connected lakes in the Yangtze River Basin, respectively. 3) The main distribution areas of freshwater Mollusca are Lake Poyanghu, Lake Dongtinghu, Lake Taihu, and the mid-lower mainstem of the Yangtze River. The established freshwater ecosystems reserves (2.1×104 km2) and rivers (1885 km) were found insufficient and scattered. They overlapped little with the predicted distribution areas. The results provide reasonable advices for biodiversity conservation of freshwater Mollusca and also systematic conservation of the Yangtze River Basin on the whole-basin scale.

     

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