Tree growth over three years in response to monthly rainfall in central Amazonia

In central Amazonia, annual rainfall distribution is characterized by a short mild dry season which is associated with a slight increase in irradiance and decline in relative humidity, but the effect of variations in these variables on tree growth is still unclear. The objective of this study was to determine how tree growth responds to monthly variations in some climate variables in central Amazonia. Trees of Protium hebetatum Daly (18–20 m tall) and Eschweilera collina Eyma (19–27 m tall) were used in the study and monthly growth rates were measured during 36 months (2010–2012). We also measured irradiance, temperature, rainfall, and relative humidity (RH). Eschweilera and Protium grew at similar rates (0.0557 mm month–1). Temperature and irradiance had no effect on tree growth of these species, but there was a trend for tree growth to increase with increasing both monthly rainfall and minimum relative humidity. If the dry season becomes longer and dryer in response to climate change one can expect that trees currently sensitive to mild drought stress will be the more affected.