Central-place analysis and modeling of landscape-scale resource use in East African agropastoral system. Landscape Ecology 16(3

Abstract

Abstract Most spatial models of grazing assume a global search; that is, the entire paddock or landscape is available to grazers. These 'unconstrained' models characterize landscape patches based on absolute properties (i.e., without regard for how individual grazers are situated within them). In most of East Africa cattle are herded and must start and end each day's grazing at their enclosure. Thus, global search is not a realistic assumption. This implies that the relative location of a patch may be more important than its absolute properties because its quality depends not only on the properties of the patch itself, but also on its location relative to home and to water. Using data from 73 full-day herd follows among a group of agropastoralists in western Tanzania, I build and test an unconstrained model and compare its analytical utility and predictive power to a 'central-place' model that defines the landscape relative to herders' homes (the central place) and dry season water. The central-place model provides analytical insights into the grazing system that are not apparent when using an unconstrained model, and it explains more of the variance in grazing intensity. Because many types of resources are collected around a focal point, central-place models should have wide applicability for analyzing and modeling many kinds of resource use, particularly in the developing world