The Kruger Experience: Ecology and Management of Savanna Heterogeneity

Edited by:
  • Johan T. du Toit,
  • Kevin H. Rogers &
  • Harry C. Biggs
Island Press: 2003. 492 pp. $75 (hbk), $40 (pbk) 1559639814 | ISBN: 1-559-63981-4
Burns unit: park rangers use fire to manage the ecology of South Africa's Kruger National Park. Credit: A. BANNISTER/GALLO IMAGES/CORBIS

The Kruger National Park, a strip of bush 60 km wide that stretches 350 km from the tropical northern end of South Africa bordering Zimbabwe and Mozambique to the temperate south, is one of the world's great wildlife reserves. The Kruger Experience is not about the experience of being there, which is breathtaking, but about the accumulated experience of the managers and scientists who have worked for a century to conserve and understand it in all its glory. The editors faced the challenge of bringing together more than a hundred researchers and getting them to put their work into a common theoretical framework. The chosen ‘cross-cutting theme’ is ecological heterogeneity in time and space, and their intention is to unravel the truism that heterogeneity underlies biodiversity and adaptive management. But there is also considerable value in the main body of the work, which is a fascinating compendium of observations on the ecology and management of the savanna biome.

Given South Africa's turbulent political past, the history of Kruger's management can be viewed against the backdrop of the changing socio-political context. Most of Africa's great national parks were established at a time when land use was allocated to suit the economic interests of colonial settlers. The new South Africa takes more seriously the land-rights conflicts that arise between conservation priorities and displaced or neighbouring farming communities. There are now many examples, as in other parts of Africa, of community-based approaches that allow local people some control over wildlife resources in a way that is more beneficial to conservation and sustainable use than strategies that dispossess local people and reduce their access to such resources.

At the outset, management interventions in Kruger were somewhat crude, such as the control of predators and fire, and the establishment of a network of water points, and were intended to increase the opportunities for viewing game. These have now given way to more subtle forms of adaptive management that attempt to recognize the complexities of natural processes within defined conservation objectives.

Fire policy provides a good illustration of the evolution of adaptive management. Fire was initially regarded as something to be avoided, but has since been seen as an integral part of natural savanna systems. Fire suppression then gave way to a policy of prescribed rotational burning in 1956. This command-and-control approach was abandoned in 1992, when it was realized that it had some negative effects and was a poor substitute for the processes by which natural fires drive and respond to vegetation heterogeneity. The next approach, which was intended to reproduce the patterns of frequency, season and intensity under which Kruger's biota evolved, allowed lightning fires to burn but suppressed anthropogenic fires. This led to the park's staff spending more time putting out fires than starting them. A mixed policy has now been adopted, in which all lightning fires are tolerated, and other fires are either started or tolerated only in areas that need to be burnt according to ecological criteria. A thorough-going state-dependent regime derived from the knowledge of how fires affect biodiversity was rejected as being too agricultural for a conservation area.

The ecological effects of establishing water points further illustrate the complexities of nature conservation and the law of unintended consequences. The provision of water was intended to allow game animals to spread into areas that were otherwise inaccessible to water-dependent species in the dry season, and to even out or homogenize vegetation use, but served to increase the number of wildebeest, zebra and their predators. Species that were less dependent on water, such as the roan antelope, now faced increased competition and heightened predation pressure from large carnivores attracted to the wildebeest and zebra. The roan antelope consequently suffered a precipitous decline in numbers, and is now endangered. In addition, the less dominant brown hyena has become extinct since the more dominant large carnivores became more common.

What, then, of heterogeneity? To those who reckon they have a common-sense understanding of heterogeneity, theoretical treatments of it are something of an acquired taste, and the two fairly heavy-duty chapters here are no exception. Authors of subsequent chapters tend to focus on their specialism, and then say either how important it is for heterogeneity, or vice versa. A few chapters are on subjects sufficiently mature for the authors to really work the theme. For example, those on the ecology and population dynamics of the large herbivore community show how, over scales from biome down to local and from geological down to seasonal, habitat heterogeneity is a driving force in ungulate speciation and abundance, the size-scaling of ungulate assemblies, and the species richness of savannas. This and other examples show that understanding the effects of heterogeneity remains an important part of the research agenda for the future — a fitting tribute to the first century of research in Kruger.

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