Efeitos da limitação nutricional do solo na dinâmica, crescimento e biomassa arbórea em uma floresta madura na Amazônia Central

Abstract

Tropical forests play a crucial role in the global climate balance, regulating water, energy and carbon cycles. In the Amazon, intact forests have functioned as important carbon sinks, but their sequestration capacity has been decreasing due to increasing anthropogenic pressures and climate change. Above-ground biomass (AGB) is a key indicator of carbon fluxes, being influenced by climatic, edaphic, and compositional factors. This study evaluated the impacts of seven years (2017–2023) of nutrient addition (N, P, and cations) on productivity, recruitment, and mortality of trees with DBH ≥ 10 cm, considering the community and different diameter classes, and analyzed the response of the relative growth rate (RGR) of the community and the four most abundant tree genera about the interaction between fertilization and seasonal precipitation in trees monitored quarterly. The results indicated a marginal effect of P fertilization on the increase in mortality rates in the community. However, timber productivity and recruitment rates were not significantly influenced by nutrient addition. Precipitation showed a positive and significant relationship with RGR, while nutrient addition showed inconsistent responses at the community level. Analyses by genus revealed distinct adaptive strategies: Eschweilera and Protium demonstrated positive marginal responses to P and cation addition, while Scleronema showed a negative response to the interaction between N and precipitation on RGR. On the other hand, the genus Pouteria showed no significant responses to nutrient addition or precipitation. These results highlight the complexity of the interactions between nutrients, water regime, and distinct adaptive strategies among the different genera that compose the forest and provide important information on the impacts of climate change and soil limitation on forest productivity in the Amazon.