Bibliografía páginas 284-286

Based on samples from 310 trees in 186 species or morpho-species collected near Manaus, Brazil, the present study finds that commonly used wood density estimates found in published lists by species need to be adjusted downward by 5.3%. Taking the average bole density from this study as a standard, wood density overestimations in three prior studies of the central Amazon were found to be 6%, 4% and 0. The arithmetic mean of the basic density of the trunk—average of the density at breast height and at the top of the bole—was 0.675 ± 0.101. The mean basic density of the bole, adjusted for tapering, and using four samples along the bole, was 0.670 ± 0.099. The arithmetic mean of the basic density for the same trees was 0.675 ± 0.098. The basic density of central heartwood was 0.766 ± 0.158. Significant differences exist between the various published estimates for Amazonian forest biomass and emissions, but we emphasize that revision of density values based on the present study will not reduce these discrepancies; instead, all estimates will shift in parallel to lower levels. Adjustments to biomass and emissions are sufficiently large to be significant for the global carbon balance. Decrease of similar proportions would apply throughout the tropics. For the 1980s, these downward adjustments total 113 × 106 Mg C/year for CO2 effects alone, or approximately 132 Mg CO2-equivalent C/year including trace gases.