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Basin Wide Studies - Forest Biomass/Carbon
Spatial Distribution of Above Ground Biomass in Amazon Basin
The amount and spatial distribution of forest biomass in the Amazon basin is a major source of uncertainty in estimating the flux of carbon released from land-cover and land-use change. Direct measurements of aboveground live biomass (AGLB) are limited to small areas of forest inventory plots and site-specific allometric equations that cannot be readily generalized for the entire basin. Furthermore, there is no spaceborne remote sensing instrument that can measure tropical forest biomass directly. To determine the spatial distribution of forest biomass of the Amazon basin, we introduce a methodology based on spatial data, such as land cover, remote sensing metrics representing various forest structural parameters and environmental variables, and more than 500 forest plots distributed over the basin. A decision tree approach was used to develop the spatial distribution of AGLB in 7 distinct biomass classes in lowland old-growth forests with more than 80% accuracy. AGLB for other vegetation types such as the woody and herbaceous savanna and secondary forests were directly estimated from the regression analysis of satellite data.
Results show that AGLB is highest in the main Central Amazon and in regions to the east and north, including the Guyanas. Biomass is generally above 300 Mg/ha here except in areas of intense logging or open floodplains. In the Western Amazon from the lowland regions of Peru, Ecuador, and Colombia to the Andean elevational gradients, biomass ranges from 150-300 Mg/ha. Most transitional and seasonal forests in southern and northwestern edges of the basin have biomass ranging from 100-200 Mg/ha. The AGLB distribution has a significant correlation with the months of dry season and the annual mean rainfall patterns across the basin. We predict, the total carbon in forest biomass of the Amazon basin, including the dead and belowground biomass, is about 86 PgC with uncertainty which compares in magnitude with the range of carbon predicted by other models
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