Estoque de carbono na madeira de diferentes densidades básicas em área de manejo florestal na Amazônia.

Abstract

Carbon has been present in trees since ancient times, quantifying its stock in the secondary xylem and bark of native forest species in the Amazon contributes to advancements in research and climate change mitigation. Basic density and wood chemical structure are characteristics that can provide this information, as they are directly related to various uses, being an important quality factor in species selection. In this context, this research aims to determine the carbon content (C) stored in the wood of twelve main species harvested in forest management plans in the State of Pará, providing detailed information that may contribute to the literature. The selected species are listed in the Forest Exploration Authorizations (AUTEF) of a Forest Management Unit under forest concession contract, in the Paru State Forest, in the State of Pará. The 12 species represent the highest volume values harvested for commercial purposes in the last 3 years. For each species, three (3) trees were selected, with a diameter at breast height of 50-150 cm, totaling 36 trees (12 species x 3 trees). From each tree, discs with 10 cm thickness were obtained in the field, at the tree base position (0%). The discs were taken to the Tree Taxonomy Laboratory of the Federal Rural University of the Amazon for basic density and C content analyses. From each disc, two opposite wedges were removed, one to determine the basic density and the other for the C content. The wood basic density data were tested for normality and variance homoscedasticity by the Shapiro-Wilk and Bartlett tests, respectively, both at the 5% error probability level. The non-parametric Kruskall-Wallis test (p <0.05) was used to verify the existence of difference between the basic density of the species. The wood density determination indicated that 66.7% of the species have high density (above 0.730 g.cm- ³), while two obtained low density category (≤ 0.550 g.cm-³) and two others with medium density (≥ 0.730 g.cm-³). The average values for basic density, among species, ranged from 0.38 g.cm-3 to 0.92 g.cm-3 for Cedrela odorata L. and Handroanthus serratifolius (Vahl) S.Grose, respectively. A range of results was observed for carbon content. Species such as A. leiocarpa (61.30%), M. elata (55.22%), and Mezilaurus synandra (55.53%) have a very high percentage of carbon content in the bark compared to carbon stored in the wood. This indicates that these species can store a significant amount of carbon in their bark. Conversely, the highest carbon content in wood was found in H. serratifolius (62.97%), differing significantly from other species, while the lowest value was for Micropholis venulosa (43.96%). The C content stored in wood differs between species and also between wood and bark of the same species, and the use of a fixed rate underestimates or overestimates the C stored in the wood of Amazon forest trees.