若尔盖湿地国家级自然保护区三种无尾两栖类陆地核心生境

Terrestrial core habitat of three anurans in Zoige Wetland Nature Reserve

若尔盖湿地国家级自然保护区地处青藏高原东缘,该地区分布有3种两栖类:高原林蛙(Ranakukunoris)、倭蛙(Naroranapleskei)和岷山蟾蜍(Bufominshanica),均为青藏高原特有种。研究在保护区内设定了16个50m×50m的样地(每个样格分为25个10m×10m样格),对每个样格中3种两栖类及环境因子进行了调查。根据3种两栖类分布点距离水体的最远距离初步确定若尔盖保护区高原林蛙(Ranakukunoris)、倭蛙(Naroranapleskei)和岷山蟾蜍(Bufominshanica)的陆地核心生境半径分别为:1000m、55m和580m。由于过大的陆地核心生境在实际保护工作中存在操作上的困难,因此本文提出最小陆地核心生境的概念:在某一季节,不同性别和生活史阶段的某种动物的90%个体完成该季节正常生命活动所通过或者利用的陆地。由此概念,根据高原林蛙90%的雌体、雄体和幼体分布确定其最小陆地核心生境半径为51m。最后通过最优化理论对高原林蛙和岷山蟾蜍分布格局与水体距离、草本层盖度、两栖类密度之间的作用机制进行了探讨,并指出陆地核心生境的范围与其所在生境景观及本种和其他动物种群状况有密切关系。

Zoige wetlands, the greatest alpine peatlands in China, are located at eastern of Qinghai-Tibetan Plateau. Three species of amphibians inhabit the wetlands, Rana kukunoris, Narorana pleskei, and Bufo minshanica, all of which are endemic to the Qianghai-Tibetan Plateau. From Aug to Oct, 2004, the distribution and body weight of these amphibian species was investigated using 10m×10m grids at 16 sampling sites （50 m×50 m） in Zoige wetland. Terrestrial core habitats were evaluated by using the maximum distance of amphibians from the nearest body of water. It has been suggested that, in late summer, the radii of the terrestrial core habitat in the Zoige wetland for R. kukunoris, N. pleskei, and B. minshanica is 1 000 m, 55 m and 580 m respectively. Estimates of core habitat that are too large may make it difficult to establish protective regulations. The smallest suitable terrestrial core habitats were defined as the terrestrial habitats used during migration to and from the wetlands, and for foraging by 90% of any life stage （males, females, and subadults） in a season. The radius of the smallest terrestrial core habitat was51 m for R. kukunoris in the Zoige wetland in late summer. There was a significant positive correlation between herbaceous cover and distance from aquatic sites. There was a significant negative correlation between amphibian density and distance from aquatic sites. Three characteristics of the girds occupied by R. kukunoris and B. minshanica were compared using correlation and partial correlation. Using the Optimality theory, we discuss the role of distance from aquatic sites, herbaceous cover, and amphibians density on distribution of R. kukunoris and B. minshanica. We suggest that the range of terrestrial core habitat was partly dependent on the landscape and population status of amphibians in our study area.