Predicting the impact of climate change on the habitat suitability and phytochemical quality of Salvia multicaulis Vahl

Background: Salvia multicaulisVahl is a medicinally valuable and ecologically sensitive species native to the Middle East. It is increasingly threatened by climate change and overharvesting. This study aimed to (1) predict the current (2025) and future (2050 and 2070) habitat suitability of S. multicaulis under two Shared Socioeconomic Pathways (SSP245 and SSP585) using MaxEnt model based on a set of climatic, topographic, and edaphic variables, (2) assess spatial variation in its phytochemical profiles, and (3) develop a quality zoning map integrating chemical and ecological data. A total of 35 occurrence records were compiled for ecological niche modeling, among which 17 representative populations were selected and analyzed for key bioactive compounds—ursolic acid, betulinic acid, oleanolic acid, total phenolics, flavonoids, and tannins—using HPLC and spectrophotometry. Results: Habitat modeling utilized 36 environmental predictors, with MaxEnt achieving a high mean AUC of 0.975. Principal component analysis, hierarchical clustering, and Pearson correlation analysis revealed distinct chemotypes and moderate correlations between compound concentrations and environmental factors, particularly soil organic carbon, nitrogen, temperature, and precipitation. Under future climate scenarios, suitable habitats are projected to shift northeast and southwest and fragment. Quantitatively, the total suitable habitat of S. multicaulis is projected to decline slightly (≈ − 2.5%) under SSP245–2050s, while modest expansions of ~ 1.8–4.3% are expected under higher-emission and long-term scenarios. Integration of habitat suitability and phytochemical richness revealed western and northwestern Iran as current hotspots for high-quality populations, while the north and northeastern regions may emerge as future refugia. Conclusions: These findings underscore the urgency of climate-informed conservation and cultivation planning for preserving both the ecological and pharmaceutical value of S. multicaulis, while supporting its sustainable harvesting from natural habitats.