Landscape-level habitat connectivity of large mammals in Chitwan Annapurna Landscape, Nepal

The populations of many species of large mammals occur in small isolated
and fragmented habitat patches in the human-dominated landscape.
Maintenance of habitat connectivity in fragmented landscapes is important
for maintaining a healthy population of large mammals. This study
evaluated the landscape patches and their linkages on two carnivores
(leopard and Himalayan black bear) and seven prey species (northern red
muntjac, chital, sambar, wild pig, Himalayan goral, rhesus macaque, and
langur) between Chitwan National Park (CNP) and Annapurna Conservation
Area (ACA) by using the least-cost path approach and the Linkage Mapper
tool in ArcGIS. A total of 15 habitat patches (average area 26.67 ± 12.70
km2) were identified that had more than 50% of the total studied mammals.
A weak relation among the habitat patches was found for chital and sambar
(Cost-weighted distance CWD: Euclidean distance EucD >100), showed
poor connectivity between the habitat patches, while the ratio of CWD and
EucD was low (i.e., low least-cost path) between the majority of the
patches for muntjac, wild pig and leopard hence had potential functional
connectivity along the landscape. Similarly, a low least cost path between
the habitat patches located in the mid-hills was observed for Himalayan
goral and Himalayan black bears. Furthermore, the multi-species
connectivity analysis identified the potential structural connectivity
between the isolated populations and habitat patches. Therefore, these
sites need to be considered connectivity hotspots and be prioritized for
the conservation of large mammals in the landscape.

在人类主导的景观格局中，多数大型哺乳动物的种群均栖息于小型孤立且破碎化的生境斑块内。破碎化景观中的生境连通性维持，对于保障大型哺乳动物种群的健康存续至关重要。本研究以奇旺国家公园（Chitwan National Park, CNP）与安纳普尔纳保护区（Annapurna Conservation Area, ACA）之间的区域为研究范围，选取2种食肉动物（豹（leopard）、喜马拉雅黑熊（Himalayan black bear））与7种猎物物种（北红麂（northern red muntjac）、白斑鹿（chital）、水鹿（sambar）、野猪（wild pig）、喜马拉雅斑羚（Himalayan goral）、恒河猴（rhesus macaque）、长尾叶猴（langur）），采用ArcGIS软件中的最小成本路径法（least-cost path approach）与连通性绘图工具（Linkage Mapper tool），对研究区内的景观斑块及其连通链路展开评估。本研究共识别出15个生境斑块，平均面积为26.67±12.70 km²，这些斑块可支撑占总研究对象50%以上的大型哺乳动物种群。针对白斑鹿与水鹿，研究发现其生境斑块间关联度较弱（成本加权距离（Cost-weighted distance, CWD）与欧氏距离（Euclidean distance, EucD）比值>100），表明生境斑块间连通性较差；而北红麂、野猪与豹的多数斑块间CWD与EucD比值较低（即最小成本路径较短），因此其所在景观具备潜在的功能连通性。同理，喜马拉雅斑羚与喜马拉雅黑熊位于中山地带的生境斑块间，最小成本路径同样较短。此外，多物种连通性分析结果显示，孤立种群与生境斑块间存在潜在的结构连通性。因此，上述区域可被视为连通性热点区域，应优先纳入该景观内大型哺乳动物的保护优先级清单。