Identifying future climate refugia in central European mountain forests

Forests are under increased pressure from anthropogenic climate change, causing profound changes in species ranges and the composition of forest communities. Some areas may sustain species in the long term, serving as refugia for existing communities.

We assessed the potential for climate refugia in Berchtesgaden National Park (Germany) and studied the effect of topographic, climatic and biotic features. Using the individual‐based forest landscape and disturbance model ‘iLand’, we simulated forest development and disturbances (wind and bark beetle outbreaks) over 1000 years under historic and future climate (Representative Concentration Pathways [RCP] 4.5 and 8.5). Refugia capacity was quantified by comparing present and future communities using a modified Bray–Curtis similarity index that incorporates both species persistence and rarity. Boosted Regression Trees were then applied to identify key environmental drivers of refugia.

Refugia capacity declined by 64.6% and 68.8% of the study area under RCP 4.5 and RCP 8.5, respectively. Low‐ and high‐elevation forests were most vulnerable to losing refugia, whereas intermediate elevations exhibited comparably less significant changes. Past management legacies were the strongest determinant of future refugia capacity, indicating a strong negative effect of the current divergence from the potential natural vegetation on refugia capacity. We found that functional redundancy has a positive relationship with future refugia capacity. Precipitation increased refugia capacity only under severe climate change scenarios. Notably, emblematic species like Pinus cembra persist in refugia also under climate change, but remain spatially restricted, emphasizing the need for targeted conservation.

Synthesis . Climate refugia could be key for the preservation of species communities in the future. We found that future climate refugia are strongly shaped by both management history and current tree functional redundancy. Identifying hotspots of refugia capacity provides a practical tool to guide conservation management strategies in mountain forests under climate change. We conclude that climate refugia should be increasingly considered in the design of protected area networks.