Variação no regime do nível de água é um drive crucial para diversidade taxonômica, funcional e filogenética em florestas tropicais sazonalmente alagadas

Abstract

Floodplains are vital ecosystems exhibiting high biodiversity and contributing significantly to terrestrial ecosystem services. However, they face escalating threats, particularly from climate change, rendering them among the most vulnerable and degraded ecosystems globally. Heterogeneity in floodplain properties arises from variations in river-specific flood regimes, watershed characteristics, and valley morphology, influencing taxonomic, functional, and phylogenetic diversity. This study addresses significant gaps in the knowledge of floodplain ecology, specifically in the seasonal dry tropics. The research aims to unravel the relationships between flood regime, environmental heterogeneity, and various ecological aspects, posing key questions regarding vegetation composition, functional and phylogenetic diversity, and the impact of environmental variables on above-ground biomass (AGB) and ecological strategies. The study encompasses six rivers within the primary river basins of southeastern Brazil, Rio Grande and São Francisco. Identifying five eco-units in each river based on flooding regime characteristics, we installed six plots in each eco-unit, measuring trees with DBH > 5cm and collecting functional traits. Detailed information on soil, climate, and hydrology was obtained. Calculations included floristic composition, taxonomic, functional, and phylogenetic diversity, wood density CWM, and AGB for each plot. Functional and phylogenetic dissimilarity were analyzed, and the impact of climate, soil, and hydrological variables was assessed using generalized linear mixed models. It identifies distinct eco-units within floodplains, revealing the influence of flood frequency and intensity on floristic composition. The study highlights functional and phylogenetic dissimilarities among eco-units and basins, suggesting potential impacts of climate change. Taxonomic and phylogenetic diversity responses to climate, soil, and hydrological variables. Functional diversity responses to hydrological variables, underscore the importance of environmental filtering in shaping these ecosystems. Hydrological seasonality, soil fertility, and flood influence emerge as key factors influencing community structure, ecological strategies. The AGB responses to soil variables, but not to climate or hydrological variables.