NECROMASS STOCK AND TREE MORTALITY IN A SECONDARY FOREST IN NORTHEASTERN PARÁ
Amazon; Carbon pools; Dead wood; Forest inventory; Wood density
Tree mortality is an important process in forest ecosystems and is associated with stand dynamics. This forest component plays an important role in biogeochemical cycles, especially that of carbon. Despite its importance, there are still gaps in the responses of tree mortality in the community and ecosystem and how generative processes occur in secondary forests. Based on this question, the following questions arose: how does the weighting of the basic density of wood, considering different classes of decomposition, influence the estimate of the necromass stock? And what can explain the death of the community's trees in this region? In order to better understand these phenomena, the study aimed to estimate the necromass stored in the woody reservoir of the decomposing material, using the basic density of the wood as an indicator, and to investigate how trees are dying in a fragment of secondary forest in the municipality of Igarapé-Açu in the northeast of Pará. To achieve this objective, this work was divided into two chapters. The first chapter addressed the tree necromass in a secondary forest in the Amazon and the second investigated possible explanations for the death of the trees in the community and analyzes their behavior within the site. The experiment was conducted inside the School Farm of Igarapé – Açu and for the measurement of the arboreal individuals (branches and trees), 30 clusters were installed in a Maltese cross layout. The results obtained for the first chapter show that statistically there is no difference in the estimate of necromass with the weighting of the basic density, however, the basic density data suffered a decrease with the increase of decomposition. The second chapter pointed out that there was no significance of dead wood for the modes of death and distance from the edge, but it is significant in the classes of decomposition and direction of fall. In summary, the study contributes significantly to the understanding of the dynamics of secondary forest stands, as tree mortality and necromass decomposition are important processes for the carbon cycle and other biogeochemical cycles. In addition, this study can serve as a basis for future research.