Spatial and temporal scaling of grazing impact on the species composition and productivity of Sahelian annual grasslands

This study compares the inter-annual effects of patch-level defoliation with the broader effects of grazing history on Sahelian rangeland vegetation. Experimental plots were subjected to a range of clipping treatments over a 2-year period within four exclosures located along long-term gradients in seasonal livestock presence. In the third year of the study, the species composition and peak standing mass of vegetation were determined on all plots. Fractions of peak standing herbaceous mass contributed by the five dominant species were not affected by clipping treatment but were strongly associated with grazing history of the exclosureʹs site. These results raise questions about standard range evaluation approaches that uncritically link contemporary range condition with contemporary defoliation pressure. Alternative range evaluation and monitoring approaches that incorporate knowledge of local production systems and land-use history are supported.