Long-term anthropogenic disturbances alter plant species composition in the Southern Atlantic forest.

It is well known that anthropogenic impacts reshape species composition and cause biodiversity loss, altering tree diversity patterns in natural forests. Here, we use a robust database encompassing three forest formations in the subtropical Atlantic Forest to determine how environmental conditions and anthropogenic impacts affect diversity patterns. We compare alpha and beta-diversity indexes using generalized dissimilarity models (GDM) within and between forest formations and two successional stages (intermediate and advanced). We found that beta-diversity across all forest formations and successional stages was mainly explained by species richness (53.3%), followed by environmental factors (26.9%), including precipitation seasonality and mean annual temperature, geographic distance (7.6%), and anthropogenic factors (7.5%). In the Araucaria forests, beta-diversity was also explained by grazing and precipitation seasonality, while in the Evergreen Forests by fire frequency, elevation and annual range of temperature. Differences in driver importance across forest formations might be related to ecological differences and distinct histories of anthropogenic impacts. By understanding the unique biodiversity patterns and human impacts across different forest types, our findings offer key insights for developing effective conservation strategies to ensure the long-term protection and resilience of these ecosystems.