PhD defence: Antoine Sambou

Antoine Sambou defends his thesis,

Vegetation change, tree diversity and food security in the Sahel: A case from the salinity-affected Fatick province in Senegal

Supervisor:
Senior researcher Anders Ræbild

Assessment committee:
Professor Erik Dahl Kjær (chair), IGN
Senior Scientist Anne Mette Lykke, Department of Bioscience, Århus University
Professor Per Christer Odén, Department of South Forest Science, Swedish University of Agricultural Sciences

Summary:
The aim of this thesis was to determine the factors that influence tree diversity and vegetation use, status and dynamics and how woody plants and palms contribute to the diets of rural communities. This thesis holds the hypothesis that changes in the land use patterns and soil salinization can reduce number of trees and palms, which can adversely affect the dietary status of rural communities.
To test the hypothesis that trees and palms play an important role in the nutrition of rural communities and represent an important source of macro and micro-nutrients, four rounds of 24 hour food recalls using a questionnaire were carried out. Results show that food obtained from tree and palm foods were important sources of vitamin B6, vitamin C, vitamin A and iron (Fe) intake in the three villages. However, the total nutrient balance was much below the recommended values for a range of nutrients, suggesting a need for an increase in the number of trees and palms in the land use system for nutrition.
The tree diversity status and dynamics were also assessed. Vegetation change was analyzed using satellite imagery, local people’s perception and botanical information. In Samba Dia, higher tree diversity was found in forest than other landscape elements. In contrast, tree richness was higher in croplands in Boly Serere and Poukham Tock. Factors such as land-use, soil salinity and pH had significant effects on vegetation parameters. Local people had observed a general decline of woody plants. This was confirmed by satellite imagery analysis.   Satellite images showed losses tree cover and mangrove, and an increase in shrub and herbaceous covers and tans. Human activities and environmental factors (especially salinization) appear to be the main drivers of vegetation change.
Overall, the vegetation change is likely to have an impact on the nutrition of local people, as they receive an important input of vitamins and minerals from food products from trees and palms.

The thesis is available from the PhD administration office, 04.1.417

After the PhD defence a reception will be held in the canteen at Rolighedsvej 23, new building