Abstract: To predict the potential suitable habitats of the rare and endangered medicinal plant Psammosilene tunicoides, we used occurrence records combined with multi-source environmental variables to construct a species distribution model, simulating the distribution of suitable habitats under current and future climate change scenarios. We further analyzed the dominant environmental factors as well as the spatiotemporal dynamics and migration patterns of the centroid of suitable habitats, by adopting optimized MaxEnt model parameters obtained via cross-validation and grid search. The results showed that: (1) The optimized MaxEnt model exhibited high predictive performance, with an AUC value of 0.979 based on the average training dataset. (2) Isothermality, altitude, annual precipitation, temperature seasonality, minimum temperature of the coldest month, and temperature annual range were the dominant factors affecting the distribution of P. tunicoides, with a cumulative contribution rate of 93% and a cumulative permutation importance of 78.8%. (3) Under current climatic conditions, the total area of potential suitable habitats for P. tunicoides was 167.47×10⁴ km², mainly distributed in eastern Xizang, Yunnan, Sichuan, and Guizhou. Among them, highly suitable habitats were concentrated in the middle and southern sections of the Hengduan Mountains, with an area of 29.65×10⁴ km², accounting for 17.7% of the total suitable area. (4) Under future SSP scenarios, the suitable habitat for P. tunicoides exhibits a phased transformation characterized by a “contraction-expansion-contraction” pattern. In the 2030s, habitat contraction is the dominant trend. After the 2050s, high-emission scenarios show expansion into the high-altitude regions of Western Sichuan and Eastern Tibet. By the 2070s, only the SSP5-8.5 scenario shows expansion, while all other scenarios experience varying degrees of contraction. By 2090s, the potential for expansion tends to become saturated. In addition, the centroid of suitable habitats generally migrated toward the northwest, and the migration rate increased with higher emission intensity. These findings provide an important scientific basis for in situ and ex situ conservation, artificial cultivation, and the sustainable utilization of germplasm resources of P. tunicoides.

Key words: Psammosilene tunicoides, MaxEnt, environmental factor, model optimization, centroid migration