Variations in precipitation and the equilibrium dynamics of a tropical forest tree community in south-eastern Brazil

Abstract

Tropical forests are dynamic communities where stochastic and unpredictable events such as climate change affect key ecological processes. The objective of this study was to describe the dynamic behaviour of a semideciduous seasonal forest during 15 years of monitoring, with four sampling intervals, in order to verify if fluctuations in forest dynamics are related to precipitation variations. The work was carried out based on diameter at breast height measured in 25 plots of 400 m² each in four forest inventories (2000, 2005, 2009, 2015). To evaluate the direction of forest dynamic changes over time, we performed analyses of mortality rates, recruitment and net changes in number of individuals and rates of loss and gain in basal area. The results suggested that the forest was undergoing a rhythmic cycle characterised by the imbalance in forest dynamics, with rates of mortality and gain in basal area greater than those of recruitment and loss in basal area respectively. However, this natural cycle may be influenced by variation in precipitation, since in the periods characterised as dry, mortality rates increased and there was less increment in basal area.