Woodland loss and restoration in a savanna park: a 20-year experiment

Woodland loss is a major cause of biodiversity decline in African savanna parks. Decisions about whether remedial steps are possible and warranted depend on the cause. Climate, fire, elephants and human impact, often in combination, have been cited as major causes. The almost complete extinction of woodland in Amboseli National Park since 1950 has been at the centre of such debate. A 20-year study based on an experimental design to test overgrazing, pathogen, climate and elephant browsing theories of woodland loss was established in 1981. The experiment showed that elephants alone are preventing regeneration. Based on the outcome of the experiment, a woodland refuge was restored in the centre of the park to maintain biodiversity and demonstrate the management prospects for habitat restoration. A strong interaction of elephants and pastoralists, played out across the ecosystem over many decades, probably accounts for the habitat mosaic and high biological diversity of the ecosystem prior to the establishment of the national park. The restoration of biodiversity in the park will therefore depend on mimicking the shifting mosaic of habitats created by their interaction.