Regional carbon stocks and dynamics in native woody shrub communities of Senegal's Peanut Basin

Estimating regional carbon (C) stocks and understanding their dynamics is crucial, both from the perspective of sustainable landscape management and global change feedback. This study combines remote sensing techniques and a coupled GIS-CENTURY model to estimate regional biomass C stocks and SOC dynamics for Guiera senegalensis shrub communities in Senegal's Peanut Basin. A statistical model relating field-measured shrub aboveground biomass C at training plots to satellite image-derived shrub abundances was developed and used to estimate regional biomass C across a major part of the Basin. Regional SOC dynamics were modeled by coupling the CENTURY model and GIS databases. Significant correlation (r = 0.73; p = 0.05) was observed between aboveground biomass C and satellite image-derived shrub abundance at the training plots. Aboveground biomass C stocks ranged from 0.01 to 0.45 Mg ha−1 with an approximate total of 247,000 Mg C for the 3060 km2 study area. CENTURY model predictions indicate that C sequestration in these systems is contingent on long-term effectiveness of non-thermal management of shrub residue and that the actual rates depend strongly on soil type and scenarios of future land management. Compared with the traditional “pruning-burned” management practice, returning prunings for 50 years would increase soil C sequestration by 200–350% without fertilization, and increase soil C sequestration by 270–483% under a low (35 kg ha−1 N yr−1; 20 kg ha−1 P yr−1) fertilization regime, depending on soil type and climate conditions. These results indicate that altered land management could contribute to transforming these degraded semiarid agroecosystems from a source to a sink for atmospheric CO2.