Abstract
This paper reviews recent changes in fire management in the Kruger National Park, and assesses the resulting fire patterns against thresholds of potential concern. In 2002, a lightning-driven approach was replaced by an approach that combined point ignitions with unplanned and lightning fires. The approach aimed to burn an annual target area, determined by rainfall and fuel conditions, in point-ignition fires of different sizes. Most of the original fire-related thresholds of potential concern (TPCs) were incorporated into the new approach. The annual target area to be burnt ranged from 12 to 24% of the park between 2002 and 2006. The total area burnt generally exceeded the targets each year, and management fires accounted for less than half of the total area burnt. The fire regime was dominated by very large fires (> 5 000 ha) which accounted for 77% of the total area burnt. New TPCs were developed to assess whether the fire regime encompassed a sufficient degree of variability, in terms of fire intensity and the spatial distribution of burnt areas. After assessment and adjustment, it appears that these TPCs have not yet been exceeded. The point-ignition approach, and its evaluation in terms of variability and heterogeneity, is based on the untested assumption that a diverse fire regime will promote biodiversity. This assumption needs to be critically assessed. We recommend that the practice of point ignitions be continued, but that greater efforts be made to burn larger areas earlier in the season to reduce large and intense dry-season fires.
Highlights
Fire plays a vital role in the coexistence of grass and trees in savanna ecosystems (Higgins et al 2000, Scholes & Walker 1993, Van Langevelde et al 2003)
We review the recent history of firerelated thresholds in the Kruger National Park and their role in the development of a new policy for fire management
The policy adopted to achieve this recognises that the effects of fire are not fully understood, and the monitoring and assessment of thresholds of potential concern is needed to improve our understanding of the ecological role of fire
Summary
Fire plays a vital role in the coexistence of grass and trees in savanna ecosystems (Higgins et al 2000, Scholes & Walker 1993, Van Langevelde et al 2003). The concept of management by “thresholds of potential concern” (hereafter referred to as thresholds) was introduced in the Kruger National Park in the early 1990s (Biggs & Rogers 2003) to address this problem. Under this framework, upper and lower thresholds were defined for a range of ecosystem indicators. Thresholds were assessed using a database of mapped fires, captured on a GIS, and included thresholds relating to fire-return periods, the seasonal distribution of fires, the range of desired fire intensities, and the size-class distribution of fire scars (see Table 1) Exceeding these thresholds would alert managers to potentially undesirable trends in fire regimes, and would trigger assessment and appropriate action. We present an analysis and assessment of the fire patterns that developed under the new policy, and make recommendations for the future management of fire in the park
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