Effects of transformation processes in 'jubraka' agroforestry systems of the Nuba Mountains, Sudan, on plant diversity and nutrient fluxes

This project started in Mai 2009, is founded by the DFG (Deutsche Forschungsgemeinschaft) and is conducted in cooperation with the University of Khartoum, Sudan.

In the Nuba Mountains, South Kordofan, Sudan, the end of a long-lasting civil war in 2005 initiated large-scale transformation processes that, among others, affected the traditional agro-ecosystems of this formerly isolated region. Nuba farmers mainly rely on two farming plot types, the 'far farm' for sorghum cultivation and the 'house farm' or homegarden, called 'jubraka', for mixed cultivation of vegetables and fruit trees. Despite their importance for farmers' livelihoods and conservation of local agrobiodiversity, these jubrakas have been largely neglected by scientists. A rapid transformation of traditional jubrakas, often into commercial vegetable gardens is partly characterized by high levels of external inputs such as mineral fertilizers, year around irrigation and pesticides. The particular structure of jubrakas as highly diverse agroforests in the Nuba Mountains provide a unique opportunity to use jubrakas as model systems for studying modernization dynamics of (sub)tropical agroecosystems.
Main objective of the planned investigation was to determine the processes and consequences of jubraka transformation.
In 'traditional' and 'commercialized jubrakas, plant species diversity, nutrient fluxes, and management was quantitatively assessed, combining agronomical, morphological, and molecular approaches to determine the relative importance of drivers of transformation processes on plant species diversity, fruit tree domestication, nutrient sustainability and food security of the local population.

Transformed jubraka in Sama with small beds harboring cash crops

Martin Wiehle (Ph.D. candidate):
Plant biodiversity of 61 homegardens, genetic diversity patterns of two indigenous fruit tree species as well as food security through homegardening and wild plant collection.

• Plant determination and inventory in homegardens
• Socio-economic parameter assessment of respective households involved
• Morphometric and genetic marker technique applications (AFLP and SSR) and analysis to evaluate human intervention on fruit traits and genetic structure
• Nutrient surveys with 24 hour recalls for food intake estimation and food security analysis      

Sven Goenster (PhD candidate):
Quantitative plot based assessment of horizontal and vertical nutrient fluxes in traditional and commercial homegardens as well as climate change studies for the Nuba Mountains.

• Socio-economic parameter assessment of respective households involved
• Horizontal carbon and nitrogen balancing to assess management related carbon and nitrogen fluxes
• Vertical gaseous emission measurements of carbon and nitrogen outputs by a photoacoustic gas monitor
• Vertical assessment of nutrient (NPK) losses via the pathway of leaching by self integrating accumulator
• Rainfall data analysis in terms of climate change and climate risks