Radial growth of seven multipurpose-use Amazonian tree species in response to intra-annual variations in rainfall, temperature and atmospheric dryness

The intra-annual increase in irradiance and temperature is associated with a short dry season in the central Amazon. Notwithstanding, the accurate effect of intra-annual microclimatic variability on tree growth of multipurpose-use species is still under investigation. The aim of this study was to evaluate how stem growth in diameter (radial growth) responds to monthly variations in microclimatic factors in the central Amazon. During four years (2018-2021) we recorded climatic data and measured stem growth of 29 trees from seven species. In order to evaluate the effect of microclimatic variability on radial growth we applied principal component regression. On average the species had a stem growth in diameter of 1.50 ± 0.74 mm yr⁻¹. The radial growth of most species increased with an increase in monthly rainfall intensity and soil moisture, while the effect of mean temperature and vapor pressure deficit varied among species. In Brosimum parinarioides, Licania micrantha, and Pouteria guianensis stem growth decreased with a rise in mean temperature, while the increase in mean vapor pressure deficit slowed down the radial growth in Brosimum parinarioides, Licania micrantha, Micropholis guyanensis, Pouteria guianensis and Theobroma sylvestre. Minimum and maximum temperatures had a neutral effect on stem growth across species. This study shows that the evaluated multipurpose-use trees are not acclimated to intra-annual climatic variability, as in addition to reducing growth during the dry season, they also responded to monthly changes in mean temperature and vapor pressure deficit, which is relevant in the face of the ongoing climate change.