Climatic suitability and distribution prediction of Medicago sativa on the Qinghai–Tibet Plateau: an ensemble species distribution modeling approach

Introduction Medicago sativa L. is a widely cultivated forage species with potential applications in the phytoremediation of heavy metal-contaminated soils. Its application on the climate-sensitive Qinghai–Tibet Plateau depends on the distribution and future dynamics of climatically suitable habitats. This study aimed to identify the main environmental constraints on its potential distribution and assess changes in suitable habitats under future climate change. Methods Using 92 spatially filtered occurrence records and 18 environmental variables, we developed species distribution models with 12 algorithms and constructed a weighted ensemble from models meeting the screening criterion. Potentially suitable habitats were projected for the current period and for three emission scenarios in the 2050s and 2090s, and key environmental variables and centroid shifts were analyzed. Results Elevation and annual temperature range were the main environmental constraints. Under current conditions, moderate- and high-suitability habitats were concentrated mainly in the eastern and southern Qinghai–Tibet Plateau. Total suitable area generally increased under future scenarios, mainly through expansion of low- and moderate-suitability habitats, whereas high-suitability habitat increased more slowly and accounted for a smaller proportion of the total suitable area. Centroid shifts varied among periods and scenarios. Discussion Climate change may reorganize the potential suitability pattern of M. sativa on the Qinghai–Tibet Plateau and provide a spatial basis for identifying candidate areas for ecological restoration. These projections represent climatic suitability rather than actual occurrence or phytoremediation effectiveness; practical application should therefore be validated against soil contamination, land use, and field conditions.