Adaptações hidráulicas de árvores do sub-bosque ao longo de gradientes do lençol freático na amazônia central

Abstract

Severe drought events are increasing with global climate change, posing significant threats to tropical forests with shallow water tables. Since high functional diversity is expected to confer resilience to ecosystems, we explore the diversity of hydraulic traits on shallow vs. deep water table forests. We analyzed leaf hydraulic traits, including stomatal conductance, modulus of elasticity, relative water content and hydraulic potential at turgor loss point, osmotic potential, and absolute leaf capacitance, in nine tree species selected to cover a gradient of water-table depth of a central Amazonian forest. Our results revealed high interspecific variation in all traits, with stomatal conductance, modulus of elasticity, and relative water content at the turgor loss point also influenced by water table depth. Trees in valleys adapted by reducing stomatal conductance during the dry season, while those on plateaus maintained higher stomatal conductance and stable osmotic and water potentials, indicative of drought resistance. Functional richness and diversity were slightly higher on plateaus, potentially due to selective pressures from seasonal waterlogging in valleys. Generalist species exhibited the highest functional diversity, enhancing resilience across different environments. These findings emphasize the importance of functional diversity and trait combinations in improving drought resilience at the community level. The study highlights the importance of considering both interspecific and intraspecific trait variability in understanding ecosystem responses to climate change. Future research should focus on severe drought conditions and include a broader range of species to better understand tolerance limits and enhance the reliability of these findings.