Densidade da madeira de florestas de ecótono da Ilha de Maracá, Roraima, Norte da Amazônia

• Autor(a) principal: Farias, Hugo Leonardo Sousa
• Data de Publicação: 2020
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da UFRR
• Texto Completo: http://repositorio.ufrr.br:8080/jspui/handle/prefix/475
• topic: Amazônia Setentrional; Gradiente hidro-edáfico; Gravidade específica da madeira; Massa específica da madeira; Northern Amazon; Hydro-edaphic gradient; Wood specific gravity; Wood specific mass; CNPQ::CIENCIAS BIOLOGICAS

The general objective of the study was to describe the variation in the basic wood density of tree communities that occur in ecotone forests in the north of the Brazilian Amazon using structural (i) structural predictor variables (composition of tree species, diameter classes and forest sites) and (ii) hydro-edaphic (altitude = drainage proxy and soil edaphic characteristics; 0-20 cm). 680 individuals were sampled with stem diameter ≥10 cm dispersed in 129 plots of 0.05 ha (6.45 ha) installed along a forest gradient located in the east of Maracá Island, state of Roraima, north of the Brazilian Amazon. For each individual sampled, bark thickness and WD were measured, here considered as the weighted average between bark density (internal+external) and wood (heartwood+sapwood). The results indicated that the spatial WD variation is not affected by the stem diameter or the forest type. The hydro-edaphic variables - altitude (drainage), texture and sum of the micronutrients - explained together 23% of the spatial WD variation of the tree species. It was observed that the distribution of WD variation in components of species substitution and intraspecific variation increased the explanatory power to 26% in the hydro-edaphic gradient. Phosphorus content alone explained only 14% of the intraspecific variation, indicating that the independent variables tested have little divergent effect when the species are analyzed individually. The analysis of interspecific variability supports that forests that occur in environments with greater hydro-edaphic restrictions in eastern Maracá are characterized by species that have WD ca 4% higher in relation to environments with less restrictions. The results achieved in this study advance the state of the art of the theme related to environmental conditions that determine the WD variation in forests in the northern ecotone of the Amazon, providing biomass/carbon estimates with a higher degree of reliability due to less error bias.