Unveiling the effects of landscape-fire interactions on functional diversity in a Southern European mountain.

Climate and land-use changes are contributing to impacts on global ecosystem functioning. These effects are particularly severe in areas undergoing land abandonment and extreme wildfire events, such as the Mediterranean regions of the Iberian Peninsula. Previous studies have evaluated the impacts of land management on fire mitigation and biodiversity (species distribution and species richness), but how such strategies influence functional diversity remains unexplored. This study investigates how alternative land-fire management strategies may affect functional diversity. We modeled for 2050 for the Transboundary Biosphere Reserve Gerês-Xurés (Portugal-Spain). Land-use scenarios simulated processes of land abandonment ("business-as-usual"-BAU) and the implementation of EU rural policies ("high nature value farmlands"-HNVf), and were combined with three fire suppression levels. Species distribution models (102 vertebrates) were projected to each scenario, and functional diversity indices were consequently calculated. The highest functional richness was predicted for BAU scenarios, probably representing the benefits to unique species that deliver singular functions. The HNVf scenarios provided the highest functional divergence, probably indicating a high niche differentiation and low resource competition amongst agricultural communities. HNVf was the most beneficial scenario for ecosystem functioning, while fire suppression did not affect functional diversity. Despite the proneness to burn of our study area and the effects of firefighting on its fire regime, land-use policies are expected to have greater influence than fire suppression effects on functional diversity. These findings suggest that different facets of functional diversity will be unevenly influenced by fire-landscape dynamics driven by the land-use policies to be implemented in the upcoming decades.