Des indicateurs spatialisés des transhumances pastorales au Ferlo

Transhumance in the Sahel has been described and mapped extensively because it represents an essential pillar for securing pastoral systems. However, very few quantifiable indicators exist to guide decision makers and policy makers for taking transhumance into account. Through a case study in the Senegalese Ferlo we propose novel indicators (spatial and not) to analyze and monitor pastoral territories as defined by the long transhumance of Ferlo’s pastoralists. We propose two indicators, computed from recorded itineraries followed by pastoralists and herds, which show the intensity of transhumance in space and time (transhumant.day.km-2), during the journey and at destination. Crossing these indicators with rainfall data indicate that transhumance is more structural and strategic than opportunistic, while somehow climate-dependent with partial correlation with total yearly rainfall. Through origin-destination matrices that summarize fluxes between departure areas (“home zones”) and destination zones (“foster zones”), we build two other indicators that are aggregated at administrative levels, i.e. the emissivity index which shows the fraction of herders that initiate transhumance from a given residency zone, and the attractivity index which shows the fraction of herders that end-up in a given foster zone. A complementary indicator shows the connectedness of these zones through transhumance, and therefore is useful for highlighting the set of zones where coordination of pastoral policies would be desirable. All these indicators based on pastoral mobility also help grasp dimensions of local interactions (such as access to resources and opportunities for trade) and regional interactions (territorial supply and demand).