Abstract:

Identifying suitable habitats for wildlife and building corridors between those habitats increases the connectivity of suitable habitat patches, enhancing gene communication, and mitigating the adverse effects of habitat fragmentation. In this study, the core distribution areas of Marco Polo sheep (Ovis polii) were determined based on a suitability index model. The lowest cost corridors were then identified using the Linkage Mapper model and their priorities were determined. Results showed that the suitable habitats of Marco Polo sheep were mainly distributed in the northwestern areas of the Taxkorgan Wildlife Nature Reserve. A total of 28 core patches (CPs) (core patches were defined as habitat patches with an area of larger than 10 km ² in summer and 5 km ² in winter) were confirmed both in summer and winter, which is a lower number and demonstrates fragmentation of suitable habitat. In total, 45 and 47 potential corridors for Marco Polo sheep habitat were identified for summer and winter habitats, respectively. The ratio of the cost-weighted distance and the Euclidean distance ratio (CWD : EucD), and ratio of cost-weighted distance and the least-cost path length (CWD : LCP) were used to evaluate the quality and importance of each corridor. Using the CWD : EucD, the top four highest quality corridors in summer were Tongku to Maeryang, Keketuluke to Paripake, Pisiling to Paripake and Haernuzi to Tongku; the top three highest quality corridors in winter were Qikeerkeer to Yaxiluofu, Satiman to Yixidaier and Qikeerkeer to Keketuluke. In comparison, using the CWD : LCP, the only two highest quality corridors were identified in summer and winter, i.e. Haernuzi to Kuokejiaer and Kuokejiaer to Maeryang in summer and Ailemixi to Tasala, the southwest of Shaerbilie to Yixidaier in winter. Current flow centrality was used to evaluate the contribution of each core patch and corridor to facilitate sheep movement. The highest contributions were from patches in Paripake, Tasala and Maeryang in summer and patches Paripake, Tasala and Maeryang in winter. The highest corridors were between patches Tongku to Maeryang, Malate to Qikeerkeer and Pisiling to Paripake in summer, and Ailemixi to Tasala, Shaerbilie to the southwest of Shaerbilie and Tieerbuerlie to Shaerbilie in winter. These results suggest that the above-mentioned CPs and corridors play key roles in maintaining connectivity of Marco Polo sheep habitats. Patches such as Zancan and Shaerbilie that are small in area and contribution little, still play an important role in maintaining the connectivity of important patches in the landscape. The results of present study will optimize understanding of functional zones and improve management schemes for conservation of this endangered species in the Taxkorgan Nature Reserve.

Key words: Marco Polo sheep, least-cost path, habitat suitability index, ecological corridor, Taxkorgan Wildlife Nature Reserve