Drylands are considered to be hotspots for climate change impacts and the Sahel in particular has been the subject of several ecological studies. Using dynamic vegetation models we aim to quantify the vulnerability of woody vegetation to climatic variability and soil properties. In this study we present the first results of our vegetation model optimization for a focus area centered on Senegal. We activated a shrub plant functional type (PFT) in the model and by comparing model simulations against Landsat cover fractions and MODIS leaf area index (LAI) data, we constrained two model parameters related to shrub rooting depth and maximum evapotranspiration rate. We found that the model is able to reproduce the observed cover fractions and LAI reasonably well, given that the model is restricted to simulating potential vegetation cover.