HOW EDAPHIC AND HYDROLOGICAL CHARACTERISTICS DRIVE PLANT DISTRIBUTION PATTERNS: A STUDY OF FUNCTIONAL TRAITS IN A SHOUTHEAST BRAZIL FLOODPLAIN

Abstract

Floodplains play a fundamental role for humanity, providing fertile soils and essential ecosystem services such as water quality improvement. However, these areas face intense human pressure, highlighting the need for research on their biodiversity and conservation. In this study, we investigated the diversity, structure, and functional traits of a floodplain by analyzing eco-units classified as Marginal Levee, High Plain, Low Plain, Lower Terrace, and Upper Terrace. NMDS analysis indicated that species composition is strongly related to the flooding regime. Inga vera was identified as the dominant species in almost all eco-units, except in the High Plain, where Machaerium villosum stood out. Carbon stock assessment revealed that the High Plain has the highest aboveground biomass (AGB) and greater heterogeneity. Using the G-test to analyze diameter class distribution, significant differences among eco-units were observed. Additionally, tree sprouting analysis showed a higher proportion of sprouted individuals in terrace eco-units, suggesting adaptation to water stress. GLMM models demonstrated that species respond conservatively to water stress, resulting in thicker, more durable leaves despite reduced photosynthetic rates. Branch density and specific branch density were also influenced by soil fertility. Our results elucidate the relationship between seasonally flooded forests and their natural flooding cycle and local soil conditions, emphasizing the need to preserve these ecosystems.