Our World Around Us
Fire is one of the most important agents capable of effecting dramatic change in ecosystems. The Lowveld Savannah is a fire-adapted system and its evolutionary history was considerably shaped by fire.
The two primary sources of fire ignition- both historic and current- are humans and lightning. Very little is known regarding the historic contribution of pre-industrial revolution humans to fire frequency, seasonality and extent, and this represents a gap in our understanding of the primary conditions to which the Lowveld Savannah is adapted to.
Archaeological and other evidence suggest that historic human habitation of the area currently represented by the Kruger was relatively sparse. The rapid increase in the human population adjoining the KNP during the 20th century, together with major changes in land-use, have resulted in greatly changed fire patterns to those which are likely to have prevailed, but we have no idea as yet as to the nature and extent of this difference.
In the early history of the National Park, a policy of controlled triennial burning was pursued, clearing the veld to prevent the build-up of combustible materials and minimising the likelihood of uncontrollable spontaneous fires. Current thinking however sees this strategy as too inflexible, simplistic, and inappropriate for the widely fluctuating conditions which result from the varied geology and soils of the Kruger, and the cyclical nature and variability of rainfall. We now perceive fire to be an essential and positive agent contributing to biodiversity within the Lowveld savannah, returning nutrients and minerals to the soil, stimulating new growth and providing a niche environment for a number of species that have adapted to its presence.
Today's strategy is to allow lightning fires to burn undisturbed and to their full extent, provided that they do not present a threat to the infrastructure of the park – the rest camps and other property. However, in the short-term and in order to allow the system to recover from the perceived excessive burns arising from historic policies, only 50% of any major fire management block will be allowed to burn due to any one particular lightning fire. A lightning fire moving into an adjoining major fire management block (there are 17 such blocks making up the KNP) will also be allowed to burn up to 50% of such a block.
Human-ignited fires are actively prevented or contained to the smallest possible area. The extent of human-ignited fires, which will inevitably arise each year due to accidental causes or arson, may be viewed as some kind of analogue for the fires, which historically humans initiated in the area. Additionally there is an effort to implement two different fire regimes as large-scale experimental blocks in order to provide some means of comparison of the long-term effect of the proposed Lightning-supported fire policy applied in the remainder of the KNP. In other words, experimental control areas are needed to see, in twenty or more years’ time, what the effect of this main fire policy is relative to other fire policies, which are successfully applied by other conservation agencies. The two sets of controls utilised are the "Trollope" Decision Support System and "Brockett" Patchwork Mosaic System, one set in the north of the KNP and another in the south.