Chilean Mediterranean forest on the verge of collapse? Evidence from a comprehensive risk analysis.

World forests are experiencing significant modification due to the confluence of climate change and deforestation, with Mediterranean forests facing particularly acute threats. The Chilean Sclerophyllous Mediterranean Forest is considered a world biodiversity hotspot, a restricted ecosystem type that is highly affected by global change drivers. Despite the high ecological and environmental importance of this ecosystem, an integrated assessment of its risk derived from climate and land-use change is lacking. This study estimates the level of risk of all sclerophyll forest stands in Chile, by assessing their exposure to several factors linked with climate change, land cover change, wildfires, change in the vegetation functional properties, and habitat fragmentation. We also generated a spatially explicit estimate of the main factors underlying the risk of each sclerophyllous forest stand. We constructed a multifactorial risk index based on the different analyzed variables, exploring the main drivers associated with the risk of each forest stand using principal components analysis with agglomerative hierarchical clustering. We found that 39.8 % of sclerophyll forest stands reached a high or very high-risk index, with the highest levels concentrated between 32°S and 34°S. The vigor and net primary production of sclerophyll forest stands decreased in 90.9 % and 86.6 %, respectively. We identified three groups of forest stands: A) northern group (29.9°S to 33.5°S), which has experienced high decrease of net primary production and vegetation vigor; B) central group (32°S to 35°S), also affected by degradation and replacement by croplands; and C) southern group (34°S to 39°S), affected by drought and exotic forest plantations. The results of this study provided clarity on the current state of the sclerophyll forest, allowing for the identification of spatial differences in the risk and their underlying factors. Our results and data can be useful for informing policy and supporting sustainable management of government agencies and practitioners.