Between processes and patterns: regeneration, co₂ sequestration, and structure in seasonally flooded forests

Abstract

Seasonally flooded forests are dynamic ecosystems in which the hydrological regime plays a key role as an environmental filter, affecting natural regeneration, floristic composition, vegetation structure, and ecosystem functioning. These formations are essential for maintaining biodiversity and a wide range of ecosystem services; however, they are particularly sensitive to climate change and are under constant pressure from anthropogenic activities. In this context, this thesis is organized into two articles. In the first, we aimed to evaluate how flooding gradients shape ecological patterns in forests by combining approaches related to germination, natural regeneration, and functional traits of two communities. Our results showed that, although flooding did not directly affect germination, it plays a central role as a postgerminative environmental filter, influencing seedling establishment and, consequently, determining regeneration patterns as well as the floristic and functional structure of communities. In the second article, we analyzed carbon sequestration in flooded forests across different phytogeographic domains. The results showed that higher CO₂ sequestration values were recorded in Caatinga forests, where this process is primarily associated with wood density and soil fertility variables. Taken together, the results demonstrate how the hydrological regime governs forest organization, exerting influence from germination to the final vegetation structure, including species distribution along the hydrological gradient. Differences in carbon stocks, expressed as CO₂, among eco-units highlight the importance of environmental heterogeneity in determining ecosystem functioning. Overall, these findings emphasize the importance of environmental diversity for the persistence of biodiversity and ecosystem services, while also providing essential information for conservation and management planning, especially under scenarios of increasing anthropogenic pressures and climate change.