Incorporating Refugia Capacity in Assessing Plant Climate Vulnerability: A Study Case on Alpine Endemics.

Anthropogenic climate change is a major threat to biodiversity in mountain ecosystems, particularly when hosting endemic species with limited ranges of distribution and low dispersal ability. These species may persist in situ if climatic conditions remain within their tolerance limits, or they can shift their range by tracking suitable habitats. We assessed the potential impact of global warming on seven endemic plant species, considering how different refugia types support species survival. Western Alps. We classified persistence areas into three categories: long-term refugia (stable suitable areas across time), holdouts (temporarily suitable areas) and stepping stones (short-term habitats facilitating range shifts). We used species distribution models to evaluate the potential impact of climate change on seven species, endemic to the South-western Alps, examining how different refugia types support their survival and whether these patterns are species-specific. We modelled habitat suitability under two climate scenarios (SSP245 and SSP585) across three future time slices, from 2021 to 2080, using five predictive models. Our results suggest that habitat suitability declines for most populations, but those of high elevation are less affected, often gaining suitability at higher elevations while losing it at lower ones. Long-term refugia are the most common persistence type under moderate climate change, whereas holdouts dominate under extreme. Stepping stones are rare, suggesting that these species may struggle to track shifting climates. The distribution of refugia types follows an elevational gradient, with long-term refugia at higher elevations and holdouts at mid-elevations. Our findings highlight the vulnerability of Alpine endemics to climate change and emphasise the importance of conservation strategies that account for range shifts, also by active translocation, to ensure their long-term survival.