Carbon Sequestration and Soil Fertility on African Drylands: Implications for Food and Woodfuel Production, Land Rehabilitation and Community Development (CASFAD)

The present project builds on previous successful dryland research in Sudan with applicability for the whole greater Horn of Africa region. Our earlier research focused on wood, non-wood forest product and agricultural crop yields, as well as on options for community-based forest management and their economic implications. A new aspect is an in-depth study on carbon cycling as related to soil water and nutrient availability. This will allow predicting the carbon sequestration capacity and bioenergy production potential on drylands under different climate change scenarios.

The specific aims are: (1) To quantify the carbon sequestration potential of forest and agroforestry systems on drylands by also clarifying the below-ground carbon dynamics; (2) To compare the soil fertility restoration process with a given time frame under tree cover on contrasting sandy and clay soils in different management systems; and, (3) Mainly based on already ongoing work in Sudan, to assess the economic and social benefits from soil fertility restoration for smallholder farmers. - The field sites consist of two contrasting locations in Sudan, one on sandy soil (representing conditions typical for western Sudan, including Darfur), and another in the central clay plain. Carbon pools and fluxes and physiological parameters of trees are quantified by applying methodologies developed at the Hyytiälä SMEAR II field station in Finland. Model and measurement estimates will be compared with eddycovariance results. Carbon isotope methods will be used for the different carbon fractions. Time series from more than 20 years of tree planting allow the quantification of biomass and carbon pool changes over time. The CO2FIX model is used to simulate the annual carbon sequestration. For socio-economic study, questionnaire survey data already collected will be complemented with new information on factors that determine the incorporation of trees in smallholder farming systems.

The project provides a new scientific and researcher-training platform for linking local and national drylanddevelopment efforts with improved knowledge on the potentials existing in dryland resources in Sudan, for sustainable bioenergy and agricultural crop production and carbon sequestration. The research results and researcher training activities can be applied for the benefit of post-war reconstruction in South Sudan. The present project offers training opportunities for researchers in other countries, especially in the Greater Horn of Africa region where VITRI has well-established contacts in Kenya and Ethiopia and where VITRI in 2007 has initiated dryland research and development work also in Somalia.