Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Linkages between carbon sequestration, soil fertility and hydrology in dryland Acacia senegal plantations of varying age in Sudan

Auteur : Abaker, Wafa

Université de soutenance : University of Helsinki,

Grade : Doctoral dissertation 2018

Résumé
Drylands cover some 40% of the global land area and are extensively degraded, especially in Africa, as indicated by reduced soil organic matter (SOM) contents. The loss of SOM and associated ecosystem services (e.g. prevention of erosion, carbon sequestration, soil fertility and water retention), threaten the livelihood of local communities. Management practices that increase SOM contents, such as increasing tree cover, can be expected to increase soil fertility, infiltration and water retention. Plantations of Acacia senegal (L.) Willd. (now Senegalia senegal (L.) Britton.) of varying age (7 to 24 years) at two sites in Sudan were used to determine : (1) biomass carbon (C) and soil organic carbon (SOC) stocks and changes in the contribution of C3 (trees + herbs) plants to SOC ; (2) SOC related changes in soil hydraulic properties, soil moisture (SM), and water balance of the plantations ; and (3) soil nitrogen (N), phosphorus (P, total and available) and potassium (K, total and extractable) concentrations and N2 fixation. Adjacent grassland areas were used for comparison (control). Tree biomass C stocks were calculated using an allometric equation and C contents ; ground vegetation C stocks by harvesting and C contents ; and SOC stocks (0-50 cm) by determining C contents and bulk density. The contribution of C3 plants to SOC was estimated using a