Projected climate change impacts on habitat suitability of threatened medicinal plants in Himachal Pradesh, Western Himalaya: an ensemble species distribution modelling approach.

Climate change is expected to profoundly influence high-elevation Himalayan ecosystems, where steep environmental gradients and narrow climatic tolerances render alpine plant communities particularly sensitive to environmental changes. Many threatened Himalayan medicinal plants occur near alpine-sub-alpine ecotones associated with upper forest limits, and shifts in their distribution may reflect broader ecosystem responses to climate change. Anticipating such range dynamics is essential for biodiversity conservation and sustainable resource management in climate-sensitive mountain landscapes. We assessed the current and future habitat suitability of three threatened Himalayan medicinal plants, Aconitum heterophyllum, Lilium polyphyllum, and Picrorhiza kurroa, in Himachal Pradesh, Western Himalaya, using an ensemble species distribution modelling framework. Species occurrence records were combined with climatic and topographic predictors to model the current and future habitat suitability. In addition to habitat suitability projections, we integrated model uncertainty, centroid displacement, and climatic niche overlap analyses to assess the robustness and spatial dynamics of future habitat changes. Ensemble models showed strong predictive performance, with the best-performing algorithms (Random Forest and MaxEnt) achieving ROC values of up to 0.90 and TSS values of up to 0.55. Habitat suitability was primarily influenced by precipitation seasonality (BIO15; importance up to ~ 0.45) and the mean diurnal temperature range (BIO2; up to ~ 0.28). Future suitability became increasingly concentrated in high-elevation districts, such as Lahaul and Spiti and Kinnaur, with suitable habitat declining by approximately 33-57% across most future scenarios. A. heterophyllum was the only species to show a temporary increase in suitable area (+ 35.7%) under SSP126 in 2050, before declining under later projections. Centroid shifts ranged from 9.4-19.4 km, while Schoener's D declined from 0.59 to 0.47 across species and scenarios, indicating increasing divergence from current suitability patterns. These findings indicate that climate change may substantially reorganise habitat suitability for threatened Himalayan medicinal plants, highlighting the potential for high-elevation refugia and providing a framework for climate-informed conservation planning in Himachal Pradesh and other Himalayan mountain ecosystems.