A detailed study on Amazon Forest structure and mortality rates through LPJ-GUESS vegetation model

Abstract: Nowadays it has become relevant for scientists to understand the impact of tropical forest structure on the Global Carbon Cycle. Dynamic vegetation models have been developed to pursue this issue, specifically by improving algorithms that could analyze the allometry, biomass content and mortality rate of each singular simulated plant individual and how this responds to climate change, management and rising CO2 concentrations. In these studies, I use and test the LPJ-GUESS vegetation model, which is an ecosystem framework for modelling the structure and dynamics of terrestrial ecosystems at landscape, regional and global scales (Smith. et al., 2001). It was used in order to simulate a better reproduction of structural tropical tree dynamics through the use of allometric equations for the scaling of the tropical tree growth in the Amazon forest. Specifically, in four locations from the Amazon forest, stand structure and developments were well reproduced by the model in comparison to observations of tropical forest structure available from the TEAM network, which provides observational information on the number of individual trees and their sizes on a range of plots across the tropics. Specifically, allometries were both investigated by adjusting standard settings in the model to reach better performances and assess how these settings impact size structure and observations. My results show that the model is not fitting the observation by not simulating accurately directly the size structure of the trees. Improper algorithms and the use of inappropriate parameter values were identified as possible explanations for the lack of agreement of the model with the TEAM network observations.