Carbon stocks in Senegal's Sahel Transition Zone

Managing carbon stocks within landscapes is a key mid-term mitigation of atmospheric and climate change. Carbon (C) stocks residing in the vegetation and soils of five sites along a 120 km north south transect within Senegal's Sahel were determined in degraded grasslands, grasslands with isolated and scattered shrubs, shrubby grasslands, and brushland with isolated trees. Total system carbon to 40 cm soil depth ranged between 12.0 and 31.2 t C ha(-1) with an overall mean of 20.6 t C ha(-1) (SEM = 1.8). The canopy cover of woody vegetation was significantly related to total system C to 40 cm (kg ha(-1)). Total soil organic C (SOC) contents were not significantly different between plant communities despite ranging between 11.6 and 25.3 t C ha(-1), an observation that is likely due to under-replication. The overall mean of SOC to 40 cm was 17.2 t C ha(-1) (SEM = 2.7) with 60 percent of that carbon residing in the top 20 cm. Woody bio-volume (m(3) ha(-1)) was calculated from canopy coverage and average canopy height, and was significantly correlated with woody biomass (p = 0.02), total biomass (p = 0.03), SOC (p = 0.05) and total system C (p = 0.02) and warrants consideration as an indicator of land quality and carbon status in the Sahel. Assuming that degraded grasslands may be restored to woody grasslands over 20 years, then C sequestration rates of 0.77 t C ha(-1) yr(-1) may be achieved. (C) 2004 Elsevier Ltd. All rights reserved.