Projected shifts in the potential distribution of Astilbe under the SSP1-2.6 climate scenario

This study aimed to project the potential distribution and habitat suitability dynamics of seven Astilbe species in China from 2000 to 2080.

MaxEnt modelling was employed under the ACCESS-CM2 climate model and the SSP1-2.6 emission scenario, integrating field survey data, herbarium records, and 23 environmental variables, under the assumption of static soil and elevation conditions.

The results indicated that annual precipitation (bio12) and elevation (DEM) had the strongest statistical associations with the geographic distribution of the genus, while temperature and soil factors played secondary roles. Under current climatic conditions, the core suitable areas are concentrated mainly in Northeast and Southwest China, with pronounced interspecific spatial differentiation: A. rubra had the greatest suitable habitat area, whereas A. longicarpa had the smallest. Under future scenarios, the total suitable habitat area of the six species expanded, with A. longicarpa being the sole exception. The direction of centroid displacement varied among species: A. grandis, A. rivularis, A. longicarpa, and A. macroflora shifted towards higher latitudes, whereas A. chinensis, A. rubra, and A. macrocarpa shifted towards lower latitudes. At the genus level, habitat redistribution exhibited pronounced interspecific variation and directional heterogeneity. A. longicarpa and A. macroflora were identified as the most potentially vulnerable species, given their extremely restricted suitable areas, the absence of highly suitable habitat under current conditions, and their continued confinement largely to Taiwan Province.

For these range-restricted taxa, strengthened population monitoring within existing native ranges and assessments of ex situ conservation feasibility are warranted. These findings provide spatially explicit information to guide conservation planning for medicinal plant resources under climate change.