Variation in wood density determines spatial patterns inAmazonian forest biomass

Abstract

Uncertainty in biomass estimates is one of the greatest limitations to models of carbon flux in tropical forests. Previous comparisons of field-based estimates of the aboveground biomass (AGB) of trees greater than 10 cm diameter within Amazonia have been limited by the paucity of data for western Amazon forests, and the use of site-specific methods to estimate biomass from inventory data. In addition, the role of regional variation in stand-level wood specific gravity has not previously been considered. Using data from 56 mature forest plots across Amazonia, we consider the relative roles of species composition (wood specific gravity) and forest structure (basal area) in determining variation in AGB.Mean stand-level wood specific gravity, on a per stem basis, is 15.8% higher in forests in central and eastern, compared with northwestern Amazonia. This pattern is due to the higher diversity and abundance of taxa with high specific gravity values in central and eastern Amazonia, and the greater diversity and abundance of taxa with low specific gravity values in western Amazonia. For two estimates of AGB derived using different allometric equations, basal area explains 51.7% and 63.4%, and stand-level specific gravity 45.4% and 29.7%, of the total variation in AGB. The variation in specific gravity is important because it determines the regional scale, spatial pattern of AGB. When weighting by specific gravity is included, central and eastern Amazon forests have significantly higher AGB than stands in northwest or southwest Amazonia. The regional-scale pattern of species composition therefore defines a broad gradient of AGB across Amazonia.

Tree Species Composition, Structure, and Aboveground Wood Biomass of a Riparian Forest of the Lower Miranda River, Southern Pantanal, Brazil

“…However, no SG could be obtained for the palm species Attalea phalerata and Copernicia alba, and for the dicot species Campomanesia eugenioides, Ruprechtia sp., Tocoyena formosa, and Capparis spinosa. When SG of single species is not available, Baker et al (2004) suggests the application of the stand-level average SG on the individuals of these species. Accordingly, we used the stand-level average SG of our study plots (0.63 g/cm 3 ) for these species.…”

Densidade da madeira de árvores em savanas do norte da Amazônia brasileira

“…De forma geral, os valores médios determinados para cada espécie em nosso estudo (0,427-0,716 g cm -3 ) estão dentro do intervalo esperado para espécies e famílias tropicais (Baker et al 2004;Chave et al 2006), sendo similares aos observados em alguns táxons arbóreos do cerrado do Brasil Central (0,35-0,75 g cm -3 ) por Bucci et al (2004). Da mesma forma, nosso valor médio geral (0,592 g cm -3 ) se encontra na mesma faixa de densidade da madeira determinada por Oliveira et al (2012) para os cerradões e cerrados típicos de Minas Gerais (0,585-0,612 g cm -3 ).…”

“…Esta finalidade é de grande importância, pois resulta na ampliação do conhecimento da dinâmica dos estoques de carbono terrestres regionalizados, tendo aplicação direta nos acordos internacionais sobre mudanças climáticas globais (IPCC 2006). No caso da Amazônia, embora o número de estudos dedicados à avaliação da DM tenha aumentado desde o final dos anos 1990, a grande maioria são de compilações ou investigações que abordam diferenças regionais ou filogenéticas de espécies de árvores de sistemas florestais (Fearnside 1997;Baker et al 2004;Nogueira et al 2005;Chave et al 2006;Nogueira et al 2007). As investigações em sistemas não florestais de baixa biomassa como campinas (Barbosa e Ferreira 2004) e savanas (Barbosa e Fearnside 2004) são raras, apesar destes sistemas ocuparem ca.…”

Soil-induced impacts on forest structure drive coarse woody debris stocks across central Amazonia

“…The individuals in each plot were matched to wood density at species level. In cases where this information was unavailable, matches were made by genus average or family (as in Baker et al 2004). When species information for a tree was missing, the mean density of known trees, weighted by basal area of the plot was used.…”