小相岭山系大熊猫廊道规划

廊道能有效地增加栖息地斑块间的大熊猫种群交流,降低种群灭绝的风险。小相岭山系是现存大熊猫种群数量最少的山系之一。通过MAXENT(Maximum Entropy)分析,发现小相岭山系存在7个相对隔离的栖息地斑块,栖息地破碎化严重。为了增加小相岭山系大熊猫种群交流,利用最小代价路径原理和电流理论,从保护管理角度出发,在该区域划定了9条连接大熊猫栖息地斑块的廊道。其中紫马-麻麻地廊道连接该区域面积最大、大熊猫痕迹点最多的两个栖息地斑块,生态意义重大,建议优先建设该廊道。此外,研究划定的多个廊道彼此邻近,甚至存在一定程度的重叠。将这些极其邻近或者重叠的廊道合并,并提出"廊道群"的概念。廊道群是两个或两个以上极其相邻的廊道构成的网状结构,廊道群作为景观上的网状结构,能同时连接多个栖息地斑块,更有效地增加多个栖息地斑块间的种群交流。由于农田的挤压,部分廊道难以达到大熊猫廊道的最低宽度需求(2230 m),制约了其生态效应的发挥,建议在以后的保护工作中探索农田区域的栖息地恢复方式。

Corridor design for the giant panda in the Xiaoxiangling Mountains

The giant panda (Ailuropoda melanoleuca) is regarded as one of the most imperiled mammals in the world. The quality and quantity of giant panda habitat have been continually and dramatically degraded due to increasing human activity and to natural disasters. In order to conserve the remaining panda populations effectively, there is a critical need to establish or restore corridors between remaining islands of habitat. This is considered essential for reducing the risk of local population extinctions. The population of giant pandas in the Xiaoxiangling Mountains is the smallest, and the habitat there is seriously fragmented. To connect the existing habitat patches and protect its local population of giant pandas, we used quantitative habitat assessment methods to assess the current structure of the Xiaoxiangling Mountains habitat and to design wildlife corridors to increase connectivity. The habitat suitability index in the study area was assessed using Maximum Entropy analysis, with "area under curve" of 0.9939 and 0.9890 for training and test sets, respectively. The habitat patches were identified following the threshold defined by the maximum Yourdon''s index. There are seven isolated habitat patches in the Xiaoxiangling Mountains (i.e., Zima, Mamadi, Gaoqiao, Shihuiyao, Luba, Dahuodi, and Wanba). Based on the least-cost path and circuit theory models, nine corridors between those habitat patches were designed. Among these corridors, the Zima-Mamadi corridor connects the two largest habitat patches, which are also where most of the giant panda activities have been recorded. Given its ecological significance, we propose that construction of Zima-Mamadi corridor should be considered top priority. In addition, some of the corridors adjoined or even overlapped. Therefore, we suggest merging these corridors into a "corridor group". A "corridor group" is defined as a network constituted by two or more closely adjacent corridors, which could interconnect several habitat patches simultaneously and effectively increase the exchange between populations in those habitat patches. Unfortunately, because of the presence of farmlands, some sections of the corridors formed extremely narrow channels. Some of these channels are narrower than the minimum efficient width of giant panda corridor (2230 m), and so their intended function could be severely impacted. However, given the complexities of land ownership, determining a way to construct corridors among farmlands should be a focus of future conservation work.