Forest Research: Open Access
Open Access

Abstract

Aboveground Biomass Dynamics in the Amazonian Rainforest under Influence of Reduction in Rainfall

Vicente de P. R. da Silva, Glayson F. B. das Chagas, Rafaela S. R. Almeida, Vijay P. Singh and Vanessa de A. Dantas

Exchange of biomass between the ecosystem and the atmosphere plays an important role in regional and global carbon cycles that have a major impact on biodiversity. This study evaluated the effect of reduction in rainfall on the aboveground biomass in an Amazonian rainforest. Data for this study were obtained from the “Long-term drought impact on water and carbon dioxide fluxes in Amazonian Tropical Rainforest Experiment (ESECAFLOR)” which was a subproject of Large Scale Biosphere Atmosphere Experiment in Amazon forest (LBA), carried out in terra firma rainforest in Caxiuanã National Forest, Pará, Brazil. The experimental design entailed two experimental sites each with one hectare of natural forest: control TFE (a simulated soil drought or ‘throughfall exclusion’ experiment) under normal conditions of climate and treatment TFE with rainfall exclusion of about 50%. The tree growth parameters employed in the study were based on monthly data from the experimental period from January 2005 to May 2009. Results indicated that a decrease in rainfall significantly affected the tree growth parameters, resulting in a decrease of biomass (21.1 t ha-1 year-1) and basal area (1.04 m2 ha-1 year-1). The Amazonian rainforest may become increasingly vulnerable to higher background tree mortality rates in response to drought events, such as El Niño.