Projected impacts of climate change and border fencing on the distribution of Khulan (Equus hemionus hemionus)

Abstract

The Khulan (Equus hemionus hemionus), a wild ass inhabiting the arid and semiarid regions of Central Asia, plays a critical ecological role in maintaining the balance of desert steppe ecosystems. However, its populations are increasingly threatened by climate change and anthropogenic barriers, necessitating urgent adaptive conservation strategies. This study investigates the combined impacts of climate change and border fencing on Khulan distribution and migration patterns. Using an ensemble species distribution models (eSDMs) implemented in BIOMOD2, completed with least-cost paths (LCP) analysis, we simulated current and future habitat suitability under multiple climate scenarios (SSP126, SSP370, and SSP585) and identified potential ecological corridors. Our findings include: (1) Habitat loss: projections indicate a > 30 % decline in suitable Khulan habitat under all future climate scenarios compared to current conditions. (2) Environmental drivers: temperature variability and water availability as the primary factors shaping habitat suitability. (3) protected area inadequacy: existing nature reserves currently cover only 16.81 % of suitable habitats, with future projections dropping to 9.56 % - 12.68 %, leaving vast critical habitats unprotected. (4) Migration barriers and connectivity solutions: the China-Mongolia border fence severely disrupts Khulan movement, exacerbating habitat fragmentation. We identified 64 potential ecological corridors, including 13 transboundary pathways, to link 17 core habitats and mitigate fragmentation effects. These results underscore the need for transboundary conservation efforts and adaptive management strategies to safeguard Khulan populations under escalating climatic and anthropogenic pressures.