Vegetation Dynamics in Oueme Basin, Benin, West Africa

Land use in Benin has been changed enormously since 20 years. The farming systems in the Oueme Basin are experiencing an ongoing intensifying process. Balancing the inherent trade-offs between immediate human needs and ecosystem capacity, needs comprehensive knowledge about ecosystem functions. To test the possible feedbacks between vegetation, precipitation and other environmental driving forces empirically, a new quantitative vegetation appraisal method was developed. Thus, the temporal and spatial vegetation dynamics of the whole Oueme Basin in Benin, West-Africa were reconstructed. The newly defined eco-volume and bio-volume concepts were used as alternative vegetation indicators in comparison with the standard biomass indicators. That portion of precipitation variability, originating specifically from vegetation variability, was defined as eco-precipitation. The in situ measured agro-ecological and farming system parameters of the three major vegetation types were used to validate the agricultural statistics and the satellite land cover data. Other available datasets comprising annual precipitation, vegetative duration coefficient and population density were adapted to comparable time and spatial spans, and eventually analysed together with the reconstructed vegetation dynamics. The feedback between vegetation and precipitation was evaluated at different spatial scales.

To detect possible future trends, static regional scenarios of precipitation in relation to eco-volume in 2004, as well as combined temporal and spatial scenarios of bio-volume in relation to precipitation from1987 to 2025 have been simulated.