Estimating the fractional cover of growth forms and bare surface in savannas. A multi-resolution approach based on regression tree ensembles

► Sub-pixel cover of woody and herbaceous vegetation and bare area is inferred for African savannas. ► A multi-resolution method is used based on Ikonos/QuickBird, Landsat and MODIS data. ► Ensemble regression trees resulted in RMSEs between 3.1 % and 9.9 %. ► Inter-resolution error propagation is assessed with Monte Carlo simulations.