Land use history and environmental filtering drive taxonomic and functional diversity in Atlantic Rainforest fragments.

The Brazilian Atlantic Rainforest is a fragmented biodiversity hotspot where anthropogenic and environmental drivers shape species composition, abundance, and dimensions of tree diversity. This study addresses how anthropogenic disturbance and edaphoclimatic and topographic environmental factors influence taxonomic and functional diversity in Atlantic Rainforest. We used forest inventory data from 136 plots across nine fragments with different land-use histories. Environmental variables and taxonomic and functional diversity indices were obtained at the plot level. We explored the relationships between the variable sets and diversity by building linear mixed-effects models (LMM), in which land-use history was included as a random effect in all models, while the remaining variables were grouped as fixed effects. The fragments were dissimilar, and taxonomic and functional diversity indices values were heterogeneous. The LMM showed varied performance among the variable groups and diversity indices, with greater influence from random effects, while climatic and anthropogenic models stood out among the fixed effects. Taxonomic indices showed similar patterns, with greater explanation by precipitation and temperature, while other models had low explanatory power. Functional indices were more influenced by climatic and anthropogenic variables, although random effects remained predominant in explaining total variance. Anthropogenic variables related to land-use history and time since abandonment, as well as climatic variables related to temperature, precipitation, and water deficit, are the main drivers of taxonomic and functional diversity in Brazilian Atlantic Rainforest fragments.