Estimating above-ground burned biomass and CO_2 emissions for tropical Africa for the year 1990 with the NOAA-NASA Pathfinder AVHRR 8 km land dataset

摘要

Biomass burning combusts Earth's vegetation (in forests, savannas and agricultural lands) and occurs over huge areas of the Earth's surface. Global estimates of biomass burning are thus required in order to provide exact figures of the gas fluxes derived from this source. In this paper we use coarse resolution images for estimating above-ground burned biomass and CO_2 emissions for tropical Africa for the year 1990. The burned land cover areas have been derived from burn scar and land cover maps using the global daily National Oceanic and Atmospheric Administration-National Aeronautics and Space Administration (NOAA-NASA) Pathfinder AVHRR 8km land dataset. A burned area estimation of (742 ± 222) Mha has been considered. Monthly maximum Normalized Difference Vegetation Index (NDVI) composites and biomass density measurements have been used for modelling the temporal behaviour of above-ground biomass for the main seasonal vegetation classes in Africa (humid savanna, derived humid savanna, dry savanna grassland and broadleaf savanna). The amount of above-ground burned biomass and therefore CO_2 emissions can be estimated from burned land cover area, above-ground biomass density, burn efficiency and emission factor of trace gas by land cover class. A total of 6494 (3675-9312) Tg for CO_2 emissions was computed for tropical Africa for the year 1990.