| Abstract: | Potential impacts of global change on dryland ecosystems are reviewed from four perspectives. First, results are reviewed from recent research on vegetation change, land degradation and desertification. The role of disturbances and low recurrence events in triggering non-linear changes by driving ecosystems beyond their resilience thresholds is outlined. Particular attention is paid to the development of spatial structures as feedbacks that tend to buffer degradation. Secondly, the synergetic operation of climatic and anthropogenic forcing factors of dryland degradation is discussed in the light of some case histories. Changes in one group of those factors often render the ecosystems particularly sensitive to changes of those in the second group. Thirdly, off-site effects of dryland degradation are summarized, including feedbacks to the atmosphere, changes in biological diversity and downstream impacts in river catchments. Finally, the implications of global change for land degradation control policies are outlined. The importance of prevention is emphasized, as well as the need to carefully consider where to apply rehabilitation and restoration. Prevention includes soft and cheap measures based on management practices, while restoration calls for massive and expensive interventions on soil or vegetation. © 1998 John Wiley & Sons, Ltd. |
