Above-Ground Woody Biomass Map of Africa, 2000-2003

Observations from the moderate resolution imaging spectroradiometer (MODIS) were used in combination with a large data set of field measurements to map woody above-ground biomass (AGB) across tropical Africa. A mosaic of best-quality cloud-free MODIS satellite reflectance observations [MODIS Nadir bidirectional reflectance distribution function adjusted reflectances (NBAR) product (MOD43B4.V4)] for the period 2000–2003 provided cloud-free spectral reflectance data for the entire region, about 20 million km2 of tropical Africa, covered by 19 MODIS tiles. The region is characterized by a diverse range of moist tropical forest, seasonal and semi-arid woodland, savanna, and wetland forests. Field measurements were then used to calibrate a regression tree model that estimated AGB for each 1 km2 pixel as a function of the spectral information derived from MODIS data. The results were cross-validated using a reserved set of field data, as well as independent lidar measurements from the Geoscience Laser Altimeter System (GLAS). The results showed a strong positive correlation (R2 = 0. 90) between the GLAS height metrics and predicted AGB. Reference: Baccini, A., N. Laporte, S.J., Goetz, M. Sun, H. Don. 2008. A first map of Tropical Africa’s above-ground biomass derived from satellite imagery. Environmental Research Letters 3 – 045011.