干旱区生态环境知识资源中心

Changes in ecological concepts and a new focus on biodiversity as a central objective have led to changes in fire policies in South African savanna parks. Prescribed burning using fixed fire intervals is being replaced by systems that promote more variable fire regimes and greater management flexibility. Three policy alternatives have been proposed for Kruger National Park: a lightning fire policy, patch mosaic burning, and burning based on ecological criteria. There is no agreement as yet on which policy to adopt. However there is growing consensus on the use of a management system using 'thresholds of potential concern' to evaluate the outcome of different policies. These thresholds have been established for numerous indicators, help focus monitoring activities, and guide managers on the need for active intervention. We discuss the applicability of the policy alternatives for preventing successional change from savanna to forest and promoting grazing lawns and their associated grazers. We conclude that none of the current policies is universally applicable. A prescriptive program of frequent, high intensity burns will be required in mesic savannas to prevent succession to forests. In arid savannas, fire regimes designed to promote variable fire frequencies and fire sizes would be preferred to maintain greater diversity of grassland swards and grazer communities. The lessons learned from fire policy debates in South African savannas are of wider relevance for managing conservation areas elsewhere.