Abstract: Functional diversity reflects how species respond to environmental gradients through variation in functional traits, yet the multidimensional trait structure of tropical palm communities remains poorly understood, particularly across hydrological gradients. Here, we quantified the functional trait space of palm communities across three contrasting ecosystems in the Colombian Orinoquia: terra firme forest, seasonally flooded forest, and permanently flooded palm swamp. We measured leaf, stem, and root traits from adult palms and constructed multidimensional functional spaces to evaluate functional richness, divergence, and trait segregation among ecosystems and species. Functional trait space differed across ecosystems and plant organs. Leaf trait space was largest in seasonally flooded forests, whereas palm swamps exhibited low leaf functional richness but high divergence. Root traits showed the strongest contraction of functional space across the flooding gradient, with palm swamps displaying the lowest richness and divergence values. Species occupied distinct regions of the multidimensional trait space, particularly for leaf and stem traits, reflecting contrasting resource-use strategies. Across ecosystems, belowground traits exhibited stronger constrained variation than aboveground traits, indicating that hydrological regimes disproportionately limit root trait variation. Our results demonstrate that hydrological filtering structures palm functional diversity in an organ-specific manner, with root traits representing the primary axis of community differentiation across the flood gradient. By integrating leaf, stem, and root traits, this study highlights how multidimensional trait approaches can reveal contrasting assembly patterns among plant organs and improve our understanding of functional organization in tropical plant communities.

Key words: Colombian Orinoquia, ecosystem gradients, flooding, functional diversity, functional traits