Climate change drives contrasting redistribution patterns in endemic and endangered Himalayan Gentiana

Abstract

O_LIRapid climate warming threatens mountain biodiversity, particularly species with narrow climatic niches and limited dispersal capacity. Mountain ecosystems are especially vulnerable because steep environmental gradients restrict opportunities for species redistribution. The Kashmir Himalaya, a globally important biodiversity hotspot experiencing accelerated warming, has already undergone an increase of approximately 0.8 {degrees}C during the 20th century and is projected to warm by 2.5-2.8 {degrees}C by the 2050s. Despite climatic changes, future persistence of many threatened plants remains poorly understood. C_LIO_LIHere, we evaluate present and future habitat suitability for two Himalayan taxa, Gentiana cachemirica, an endemic species, and Gentiana kurroo, a critically endangered species. Specifically, we quantify how climate change and topographic variability influence species distribution and persistence under multiple emission scenarios. C_LIO_LIWe applied species distribution models (SDMs) to presence data of both species and forecasted habitat suitability under four Shared Socioeconomic Pathways (SSP126, SSP245, SSP370, and SSP585). We hypothesized that G. cachemirica, a narrow-niche, low-dispersal species, is expected to lose habitat due to thermal sensitivity, while G. kurroo may persist or expand under favorable scenarios because of broader tolerance and higher dispersal. We also expected microclimatic refuges to buffer populations, whereas extreme warming would accelerate habitat decline. C_LIO_LIThe predictions of our SDMs under current conditions indicate a highly restricted and fragmented habitat for G. cachemirica, covering 651 km{superscript 2}, but a broader suitable area (2,452 km{superscript 2}) for G. kurroo. In agreement with our hypotheses, our forecasts indicate severe habitat contraction (55-70%) for G. cachemirica across all SSPs, but scenario-dependent responses for G. kurroo, including modest expansion under low-emission scenarios and severe declines under high-emission scenarios. Centroid analyses suggest pronounced climate-driven range shifts, with G. kurroo projected to migrate up to 33 km toward the east-southeast by 2100, while G. cachemirica is projected to display limited dispersal capacity. C_LIO_LISynthesis. Our findings suggest that climatic niche breadth, dispersal limitation, and topographic buffering strongly mediate species responses to warming in mountain ecosystems. Endemic specialists are projected to experience disproportionate habitat fragmentation and range restriction, highlighting the importance of conserving climatic refugia and elevational connectivity under rapid environmental change. C_LI