WHAT IS THE IMPACT OF 21 YEARS OF WATER REDUCTION ON SPECIES COMPOSITION, BIOMASS AND FUNCTIONAL CHARACTERISTICS IN EASTERN AMAZON?

Climate Change, Vegetation Dynamics, Functional Diversity, Drought.

The Amazon is a region with a humid tropical climate, with high rainfall throughout the year. However, in recent decades, there has been an increase in drought events in the region, which can be attributed to a combination of factors, such as global climate change, deforestation and forest degradation, and natural extreme drought phenomena. Drought in the Amazon can have serious consequences for the region and the world as a whole, as the Amazon forest is an important carbon sink, helping to mitigate global climate change, as well as being home to a great diversity of animal and plant species. During prolonged periods of high drought, plants suffer from water limitation, which can lead to increased mortality rates for species that are less drought-resistant. The increase in mortality can impact species composition, biomass production, and functional characteristics. Therefore, it is essential to understand the responses of Amazon tree species to drought in order to improve predictions about the future of these forests in the face of climate change. In order to predict how the Amazon forest will respond to predictions of water reduction due to climate change, a rain exclusion experiment (throughfall exclusion - TFE) was developed in the eastern Amazon, in the Caxiuanã National Forest. Using data from this experiment, which is the longest in tropical forests, this thesis project aims to evaluate how 21 years of experimental drought has impacted species composition, above-ground biomass, and to understand if functional characteristics are predictors of drought-induced mortality risk. We hypothesize that water reduction will modify the community composition in favor of drought-affiliated species. We also expect that there will be a reduction in above-ground biomass over the years, especially due to the mortality of large trees. In addition, we believe that species with functional characteristics related to lower mechanical resistance and greater resource needs will have a higher mortality rate.