Session A6Rangelands as dynamic systems — Fragmentation of rangelands: ecological and economic implications. A tribute to Jim Ellis

Abstract

Biological complexity in rangelands arises from spatially-linked ecological states and processes. Herbivores, humans and other agents integrate distinct spatial units into complex systems by moving among and exploiting these units. Spatial heterogeneity plays a central role in the structure and function of grazed ecosystems, but modern human land-use tends to compress the scale at which people and animals can respond to heterogeneity by fragmenting large intact landscapes. Fragmentation is the breaking apart of habitat without incurring habitat loss — in grazed ecosystems this usually implies a diminished ability of large herbivores to access natural heterogeneity in vegetation and topography. As fragmentation occurs, ecosystems are simplified by breaking up interdependent spatial units into separate entities, compartmentalising them into isolated sub-units. The result of this simplification is a reduction in the scale over which complexinteractions among environment, large herbivores, and human management takes place. In this symposium, we consider the effects of fragmentation of rangelands and ensuing loss of biological complexity for a variety of processes including behaviour and performance of large herbivores, responses of plant communities to herbivory, and functioning of human social and economic systems. We invite posters that consider quantification of complexity and fragmentation, that describe biological and human consequences of fragmenting grazed ecosystems, and that address options for management and policy aimed at enhancing biological complexity and spatial integrity of grazing systems worldwide.


African Journal of Range & Forage Science 2003, 20(2): 113-116