Potential connections (least-cost paths) between existing and potential bison habitat patches in the Carpathian Mountains

Habitat connectivity is important for the survival of species that occupy habitat patches too small to sustain an isolated population. A prominent example of such a species is the European bison (Bison bonasus), occurring only in small, isolated herds, and whose survival will depend on establishing larger, well-connected populations. Our goal here was to assess habitat connectivity of European bison in the Carpathians. We used an existing bison habitat suitability map and data on dispersal barriers to derive cost surfaces, representing the ability of bison to move across the landscape, and to delineate potential connections (as least-cost paths) between currently occupied and potential habitat patches. Graph theory tools were then employed to evaluate the connectivity of all potential habitat patches and their relative importance in the network. Our analysis showed that existing bison herds in Ukraine are isolated. However, we identified several groups of well-connected habitat patches in the Carpathians which could host a large population of European bison. Our analysis also located important dispersal corridors connecting existing herds, and several promising locations for future reintroductions (especially in the Eastern Carpathians) that should have a high priority for conservation efforts. In general, our approach indicates the most important elements within a landscape mosaic for providing and maintaining the overall connectivity of different habitat networks and thus offers a robust and powerful tool for conservation planning.

生境连通性（habitat connectivity）对于栖息于面积过小、无法维持孤立种群的生境斑块的物种的生存至关重要。此类物种的典型代表为欧洲野牛（Bison bonasus），它们仅以小型孤立种群形式分布，其存续依赖于构建规模更大、连通性更佳的种群。本研究旨在评估喀尔巴阡山脉地区欧洲野牛的生境连通性。我们利用已公开的野牛生境适宜性地图（habitat suitability map）与扩散障碍（dispersal barriers）数据集，生成表征野牛跨景观移动能力的成本表面（cost surfaces），并勾勒出当前已占用生境斑块与潜在生境斑块之间的潜在连通路径（即最小成本路径（least-cost paths））。随后借助图论（graph theory）工具，评估所有潜在生境斑块的连通性及其在连通网络中的相对重要性。分析结果显示，乌克兰境内现存的野牛种群处于孤立状态。但我们在喀尔巴阡山脉中发现了多组连通性良好的生境斑块，这些斑块可支撑大规模欧洲野牛种群的存续。本研究同时定位了连接现存野牛种群的关键扩散廊道（dispersal corridors），以及数个适合未来开展再引入（reintroductions）工作的潜力点位（尤其在东喀尔巴阡山脉地区），此类点位应被纳入保护工作的优先名录。总体而言，本研究方法可识别景观镶嵌体（landscape mosaic）中维系不同生境网络整体连通性的核心要素，因此可为保护规划（conservation planning）提供一套可靠且高效的分析工具。