This study was conducted in Caxiuanã National Forest, Pará, Brazil, to analyze the effects of decrease in rainfall on biomass, tree mortality and basal area of tropical rainforest within ESECAFLOR Project (LBA). Two experimental sectors with one hectare each of natural forest were utilized. Plot A was maintained under natural conditions of climate and Plot B with rainfall exclusion of about 90%. The growth parameters presented in this study refer to monthly data during the experimental period from 2005 to 2009 for the two experimental plots. Results showed that a decrease in rainfall affected significantly all tree growth parameters over forest. The main evidence for this is that rainfall exclusion provides a reduction in basal area especially with Diameter at Breast Height more than 10 cm. Also, an increase in both tree mortality rate and consequently loss in plant biomass are larger in forest area with rainfall exclusion than under natural conditions of climate.
Amazon; LBA; basal area; mortality of trees; precipitation
