Integrating Habitat Suitability and Soil Heavy-Metal Contamination to Identify Conservation Priorities for the Mongolian Wild Ass

In arid regions, water scarcity and limited vegetation regeneration capacity make the habitats of large herbivores particularly vulnerable to climate change and human activities. However, conventional habitat-suitability assessments may overlook potential environmental pressures associated with soil heavy-metal contamination. This study used the BIOMOD2 ensemble modeling framework to predict potential habitat suitability for the Mongolian wild ass under current environmental conditions and future climate scenarios. Current habitat-suitability predictions were further overlaid with soil heavy-metal contamination classes derived from the Nemerow integrated pollution index to examine their spatial correspondence. Under four-fold spatial block cross-validation, the EMca ensemble achieved an AUC of 0.893 ± 0.032 and a TSS of 0.610 ± 0.048. Distance to water sources was the most influential predictor, accounting for 43.76% of the total normalized variable importance. Highly suitable habitat was projected to decline from 0.4637 × 104 km2 under current conditions to 0–0.1180 × 104 km2 across future climate scenarios, with particularly pronounced reductions under SSP370 and SSP585 during the middle and late future periods. The spatial overlay analysis showed that 73.56% of current highly suitable habitat overlapped with light pollution, 24.31% with warning-level contamination, and 2.12% with moderate pollution. These findings indicate that high habitat suitability does not necessarily correspond to low soil-contamination levels. By integrating habitat suitability and soil-contamination patterns, this study provides a spatial basis for identifying conservation-priority habitats and areas requiring targeted environmental monitoring in Kalamaili National Park.