Most Southern African Biomes need fire to maintain biodiversity. This may range from an average rotation of fifteen years in the fynbos-covered mountains of the Cape regions and drier grassland communities, to as little as two to four years in the moister summer rainfall areas, but throughout Southern Africa, the important role of fire has never been questioned. As a result of changes in land-use, some biomes have changes significantly over the years, and the establishment of industrial plantations in the higher rainfall areas, demarcation of nature reserves, intensive agriculture and shifting grazing patterns in rural areas have no doubt changed biomass characteristics of the land, but the role of fire was maintained throughout the process, although in places in a somewhat revised form.
The inherited role of fire in forestry plantations was not recognised before the 1980’s, by which time serious wildfires occurred at an increased rate, threatening the sustainability of timber supplies. The “total protection policy” applied in these plantations – completely excluding fire from planted areas – increased fire hazard steadily, as fuel accumulation ran out of control in many forest regions. It was only during the 1990’s that fuel management was considered as a viable fuel level control technique, and that selective use of prescribed burning was accepted as an important long-term solution to combat the increased wildfire problem (de Ronde 1990, 1997, de Ronde et al. 1990).
On a regional scale, the mixture of natural ecosystems, agricultural land and forestry activities was never considered on a broader scale, and the fuel status/dynamics of these regions was before the early 1990’s not appreciated either. This resulted in fragmented fire protection measures following (mainly) historical property boundaries, with a serious lack of continuous protective lines through the landscape. As a result the occurrence of large wildfires increased.
The top-down approach
Wrong placement and inadequate widths of fire breaks, and a lack of understanding of wildfire hazard at regional level had to be dealt with and to overcome these problems, fire protection improvement was scheduled in the following order:
Regional appreciation phase
Fire protection evaluation at plantation level
Integrated fire protection application phase
Regional appreciation phase
Mapping fire history: Before considering fire protection measures, the perimeters of major wildfires experienced in the past were mapped on topographical maps at a 1:50,000 scale, in order to determine the main direction(s) and area(s) of wildfires that occurred in the past.
Classifying basic fire hazard categories: To make evaluation at a regional scale more meaningful, a typical basic fire hazard classification used to express external fire hazard has been presented below (Tab.1).
Tab. 1. Regional fire hazard grading used
Extremely high fire hazard
Montane grassland irregularly burned.
Unmanaged Wattle jungle.
Rural settlements situated on the dangerous, wind-exposed side.
High fire hazard
Irregularly burned wetlands.
Industrial sites, e.g. sawmills.
Plantations consisting mainly of Eucalyptus.
Medium fire hazard
Yearly burned montane grassland.
Yearly burned wetlands.
Plantations consisting mainly of Pinus.
Rural settlements situated on the less dangerous leeside.
Placing the main buffer zones: A range of 800 – 1500m wide dynamic buffer zones were developed, placed diagonally against the direction of wildfire threat. As these zones would require too many hectares of naturally vegetated areas (montane grassland, savanna or fynbos) at the expense of planted areas, it was decided to include both yearly-burned vegetation such as grassland (where available), as well as existing mature Acacia mearnsii stands within these zones. The latter proved to be highly resistant against fire as a result of the lack of forest floor biomass/available fuel inside mature stands.
Prescribed burning inside stands was also introduced as a fuel reduction measure inside zones, while yearly weed control was also used to restrict fuel development, in stands too young for prescribed burning to be applied. Yearly-maintained roads, rivers with evergreen riverine forests, mountain forests and steep rocky slopes were also incorporated in buffer zones to make up the total area required, provided available fuel levels were sufficiently reduced to bring a high intensity, crowning and spotting wildfire down to a low intensity, manageable, surface fire.
A set of unique fuel models was developed for each forest region, to be used as a basis for site-specific fuel classification systems that could be used as input for BEHAVE runs required for fire behaviour testing (Burgan and Rothermel 1984). The regional plan also included a disaster management plan and regulations regarding the co-ordinated use of aerial and ground attack in the case of serious wildfires.
Plantation fire protection evaluation phase
Fuel modeling and fuel classification: The fuel classification system developed with the assistance of site-specific fuel models, using BEHAVE (op cit.), also made it possible to arrive at actual and predicted fire hazard ratings at plantation level, which provided the information needed to arrive at more realistic fire protection requirements, particularly with regard to fire belt routes and width.
Mapping fire hazard rating: Present and future predicted fire hazard ratings were mapped, illustrating both the existing fire hazard, as well as the predicted status of fire hazard in the future. These maps made it possible to identify hazardous areas, to quantify fire hazard and to determine any predicted major shift(s) of fire hazard over time.
Evaluating existing fire protection measures: During this process all the previous studies conducted were considered, and note was taken of calculated fire protection requirements. A preliminary plan of action was then drawn up.
Integrated fire protection application phase
This is the application phase when recommendations were considered, conducted after the regional and plantation-level evaluation processes were completed. All proposed measures now had to be integrated with the conservation programme, the plantation working plan and other disciplines. Nature conservation plans and riparian zone management requirements were also successfully integrated into the revised fire protection plans.
Fire hazard reduction and improved fire break placement
The fuel modelling/fire hazard rating mapping, at regional and at plantation level, proved to be an effective way in which fire hazard could be evaluated and used to reduce areas at risk in case of a wildfire. This was particularly true for the Melmoth district in the Kwazulu-Natal Province, which had experienced three major wildfires over a period of four years (destroying 2000-5000 ha at a time) before the new system was implemented.
The most important outcome of the Melmoth, and also Mpumalanga Highveld and North East Cape regional fire protection evaluation exercises was that, for the first time, regional fire protection systems could be placed across property boundary lines for optimum results.
Stopping major runaway fires
The regional buffer zones created have already resulted in stopping some major wildfires from entering plantations, where standard fire break systems (such as yearly-burned grassland fire belts) failed to do so in the past. Internal fires were also significantly restricted, particularly in the Melmoth and Swaziland regions.
Reducing plantation areas at risk
Plantation areas at risk were significantly reduced by more effective internal belt placement in conjunction with major buffer zone systems, aiming at reducing exposed areas to 300-500 ha protection units. In the Sappi Forests Highveld District, foresters managed to reduce the area at risk inside plantations with an average 37%, while simultaneously reducing fire break preparation costs with 25% and reducing the external risk of wildfire significantly. Similar success was achieved in other forest regions.
Integration of the conservation burning programme
In most cases the optimum burning rotation recommended for e.g. ecologically-sensitive wetlands is two to three years, while grassland burning requirements for fire protection purposes is a yearly fire application. This gave rise to conflicting needs for forestry and nature conservation. By re-scheduling the conservation burning programme, by means of applying prescribed burning in a specific mosaic sequence that fitted into the fire protection burning schedule, it was possible to satisfy both the plantation burning requirements as well as the recommended conservation burning policy.
Plantation fuel management
The selective use of prescribed burning inside plantation stands not only proved to be a cost-effective management tool for fire protection purposes, but was also used to introduce fuel reduction programmes where previously only the use of slash burning after clearfelling could be considered to reduce fuels. Chains of prescribed burned plantations of fire resistant species such as Pinus elliottii, Pinus pinaster and Pinus taeda were used to strengthen buffer zone systems along hazardous boundaries in a cost-effective way, replacing less effective hand, or mechanically-prepared, fire belts. Eucalyptus grandis, Pinus patula and Pinus radiata stands were sometimes also used for this purpose, but because these trees are more susceptible to fire damage, they could only be incorporated at older age, restricting prescribed burning application potential. However, in P.patula stands, further burning experiments are now being conducted first to determine the possible use of prescribed burning.
Fig. 1. Pine plantations embedded in fire-prone environments, such as the fynbos ecosystems, are subjected to extreme wildfire risk without proper fuel management. Photo: GFMC/IFFN
Fig. 2. Fires occurring at the wildland-urban interface are a common problem in Southern Africa and involve a high risk of property losses. Photo: GFMC/IFFN
Riparian zone maintenance
Water is a scarce commodity in Africa. The new system has also been used to advantage to correct wrong fire belt placement, to benefit both maximum water flow and optimum fire protection. This has resulted in a better long-term approach to riparian zone maintenance, as well as fire protection improvement, in the Usutu Plantations (Swaziland), and on the Mpumalanga Highveld and in the North East Cape (South Africa).
Practical application of the new, flexible, methods to improve fire protection have resulted in a few exciting success stories in Southern Africa over the last four to five years. Use of the new regional approach, and the application of a fuel modelling base, are now also being considered in various other Southern African regions.
The basis for the success was to move away from rigid, ineffective, fire belt systems, towards dynamic, (better placed) buffer zones, the incorporation of selective use of prescribed fire inside natural biomes and forestry areas.
The direct and indirect financial implications of the new system are substantial, but training and applied fire-related research will also have to form an integral part of the application of the new techniques.
Burgan, R.E., and R.C.Rothermel. 1984. BEHAVE: Fire behavior prediction and fuel modeling system-fuel subsystem. Gen. Tech. Report INT-167. USDA For. Serv. Intermountain Forest and Range Expt. Stn. Ogden, UT, 126 pp.
De Ronde, C. 1990. How to use forest floor characteristics to determine litter reduction priorities, rate of fire hazard and feasibility of controlled burning. Proc. 1st Int. Conf. on Forest Fire Research, Coimbra, Portugal (1990), B01, 1-10.
De Ronde, C. 1997. Dynamic fire protection in Southern African Plantations. Paper delivered at the 2nd International Wildland Fire Conference, Vancouver, Canada, May 1997: Economic perspectives.
De Ronde, C., J.G.Goldammer, D.D.Wade, and R.V.Soares, 1990. Prescribed burning in industrial plantations. In: Fire in the tropical biota. Ecosystem processes and global challenges (J.G. Goldammer, ed.), 216 – 272. Ecological Studies 84. Springer-Verlag, Berlin-Heidelberg.
Neels De Ronde SILVA Forest Services
du Toit Street 16