Functional traits underlie dominance and rarity patterns across the subtropical Brazilian Atlantic Forest

Understanding forest community assembly requires identifying the ecological strategies that differentiate dominant, subordinate, and rare species, and how they shape ecosystem functioning through abundance, carbon storage, and productivity at local and regional scales. Here, we identified regionally hyperdominant and locally dominant, subordinate, and rare species based on abundance, carbon storage, and wood productivity. We assessed the consistency of species dominance across scales, the correlations among abundance, carbon storage, and productivity, and how leaf, structural, and reproductive traits shape dominance patterns. To address these questions, we analysed 607 species across 175 plots in the subtropical Brazilian Atlantic Forest, encompassing its major forest types, and local communities. At each scale, species were classified as dominant (top 10%), subordinate (11–89%), or rare (bottom 10%) based on abundance, carbon storage, and productivity. In addition, we evaluated the distribution of seven functional traits for each parameter at the local scale. The top three hyperdominant species across all evaluated parameters were Araucaria angustifolia, Euterpe edulis, and Alchornea triplinervia. Carbon storage and productivity were strongly correlated, whereas their correlations with abundance were weaker. Locally dominant species exhibited distinct functional trait values compared to subordinate and rare species across all dominance parameters, particularly associated with tree stature, leaf structure, and wood density, revealing ecological strategies that enhance species performance. Dominant species are fundamental for maintaining ecosystem functioning through abundance, carbon storage, and productivity. Complementary, subordinate and rare species may contribute unique trait values that potentially promote long-term ecosystem resilience, particularly under ongoing global environmental changes.