By
Hugh Eva & Jean-Marie Grégoire
Space
Applications Institute,
Joint Research Centre of the European
Commission,
Ispra, Italy
Vegetation and fire environment
In the Central African Republic (RCA), there are three major vegetation formations as defined by UNESCO (White 1983): Sudanian, Guineo-congolia/sudania, and Guineo-congolia. These three formations form lateral bands covering the dry savannahs in the north, the wet savannahs in the centre and the humid forests in the south. The Sudanian region is predominantly open woodland savannahs.
The transition zone of the Guineo-congolia/sudania consists of secondary savannahs and woodlands with some open forest. These savannahs are deemed to be fire-maintained. In areas where there has been a decline in population, a regrowth of woody biomass has occurred. In the southern part of this transition zone, mosaics of dense forest and secondary savannahs are found.
The Guineo-congolia region is predominantly dense humid semi-evergreen forests (both terre firme and flooded), which are rarely subjected to fire, and of included savannahs. These included savannahs are very important in terms of biodiversity. Running north-south, the central Plateau of Ouadda is dominated by remnant forest. A more detailed partition of the vegetation types has been undertaken by Boulvert (1986). Fire activity starts in the northeast of the country around November, and moves southwest following the Harmattan winds, reaching a peak in late December, or early January. The onset of rains in March terminates the fire season.
Major fire impacts
While there are no official data available, there is a perception at government levels that vegetation fires have various detrimental impacts. Since the economy relies heavily on small-scale agricultural production, the accidental destruction of cultures is of major concern. The intensive use of fire throughout the region for agricultural practices, hunting and pastoralism threatens the sustainability of natural resources. Soil erosion on the hills around the capital, Bangui, has been linked to cultivation and intensive burning. Visitors to Bangui will note the poor air quality due to smoke particles in the dry season. The deposition of acid rain over the forests downwind of RCA’s savannahs has been linked to the burning of savannahs.
Fire database
Little or no data exist to document the impact of fire over the last 20 years. A suite of scientific experiments was carried out in the mid-1990s on the sources of atmospheric pollutants in the regions. Under this initiative, EXPRESSO (Experiment for Regional Sources and Sinks of Oxidants), a satellite receiving station capable of receiving the NOAA-AVHRR data and detecting fires, was installed at Bangui. Data were collected for the 1993-94 and 1995-96 dry seasons. For the 1994-95 dry season, a study by Eva and Lambin (1998) using satellite data estimated that just over 43 percent of Sudanian savannahs burned and 58 percent of Guineo-congolia sudanian savannahs burned. This corresponds to an area affected by fire of 86 000 km² and 191 000 km², respectively. The 1994-95 dry season is considered to represent an average fire season.
The area of forest affected by fires is difficult to assess in the absence of a suitable forest database. The work done by Eva and Lambin (1998) detected 2 486 cases of fires in “forested” areas. However, a close inspection of the data revealed that all these fires were on the edge of the forest domain. Some were likely for the purposes of establishing coffee cultures. It is not, however, possible to quantify these in terms of area of forest burned.
Operational fire management
Fire management is undertaken at the local level, where the decision to burn certain areas is decided at the village level. This usually covers areas within five kilometres of the road network. The government has tried to encourage a conservative approach to burning by the use of radio campaigns. Realising that lack of knowledge was one of the main obstacles to effective fire management, the RCA government, with the help of the ADIE (Association pour le Développement de l’Information Environmementale) and the EU Joint Research Centre, has installed a permanent satellite receiving station at Bangui. The objective is to work with the CNLIFBAC (Comite National de Lutte contre les Incendies, Feux de Brousse et Autres Calamités) to document the occurrence of fires in different vegetation strata, and to predict regions at risk of fires.
The data will be used to sensitise public opinion to the problems of fire using TV and radio campaigns and to organize prescribed burning. At the same time, the data can be used to better organize the campaign against illegal hunting. Under the same initiative, a study will be carried out on the economic effects of fire on the country.
Use of prescribed fire
Fire is used extensively across RCA. There are three main activities.
• Large scale poaching: This has its greatest impact in the north and north east of the country. The open savannahs of the Northeast, on the Sudan border, see large fire fronts (50 km) every year, moving southwest as the season progresses. The fires start on the frontier with Sudan in November and move southwest, arriving at Bakouma in February. These are thought to be due to large scale poaching activities. A similar process occurs in the north of the country on the frontier with Chad. Fires of several km’s size advance down towards the Massif des Bongo during November, December, and January. This area is comprised of several national parks. The fires are smaller than those found in the Northwest as the landscape is more fragmented with rivers and woodlands. The Plateau of Ouadda, south of the Massif, sees many large hunting fires later in the season (January to March). This remnant forest area is a home to bush game.
• Pasture management: Fires are used to stimulate re-growth for cattle in the dry season. This occurs around the town of Bambari (central RCA) and on the routes from Northwest RCA (a livestock breeding area) to the markets in the south. The herdsmen light fires along the route both to stimulate regrowth and to facilitate passage. These fires tend to be at least five km from the road network. The fires are small in size and start in December and continue until March.
• Agricultural fires: These small fires occur across the country in December and January, but are predominantly close to the road network, being lit to prepare the fields for agriculture. At the same time, farmers burn the area around their crops and villages earlier in the season to avoid accidental fires caused by the passage of pastoralists. The conflict between the two groups, pastoralists and villagers, is a well-known one.
The CNLIFBAC intends to propose a “fire calendar” to the population to manage the spread of fire across the country.
Sustainable land-use practices employed in the country to reduce wildfire
Burning around villages before the migration of cattle through the areas is carried out to reduce the threat of wildfires.
Public policies concerning fire
The government’s policies are persuasion rather than enforcement, making use of television and radio campaigns. At present, the lack of information on the presence and impact of fires is the major obstacle to an effective national policy. The current initiative to develop an information system to document the occurrence of fires is a first step. At the same time, the receiving station is one of a network of sites contributing to the World Fire Web, organized by the GVM unit of the European Commission’s Space Application Institute. This will enable the country’s fire activity to be documented in the regional and global perspective.
References
Boulvert, Y. 1986. Carte phytogéographique de la République Centrafricaine, 1:1 000 000. Paris, ORSTOM.
Cachier, H. & Ducret, J. 1991. Influence of biomass burning on equatorial African rains. Nature 352: 228-230.
R.A. Delmas, Druilhet, A., Cros, B., Durand, P., Delon, C., Lacaux, J.P., Brustet, J.M., Serça, D., Affre, C., Guenther, A., Greenberg, J., Baugh, W., Harley, P., Klinger, L., Ginoux, P., Brasseur, G., Zimmerman, P.R., Grégoire, J.M., Janodet, E., Tournier, A., Perros, P., Marion, Th., Gaudichet, A., Cachier, H., Ruellan, S., Masclet, P., Cautenet, S., Poulet, D., Bouka Biona, C., Nganga, D., Tathy, J.P., Minga, A., Loemba-Ndembi, J. & Ceccato, P. 1999. Experiment for regional sources and sinks of Oxidants (EXPRESSO): An overview. J. Geophys. Res. 104: 30 609- 30 624.
Eva, H. & Lambin, E.F. 1998. Burnt area mapping in Central Africa using ATSR data. Int. J. of Remote Sensing 19: 3 473-3 497.
White, F. 1983. Vegetation Map of Africa. Paris , UNESCO.
Source
Eva, H. & Grégoire, J.M. 2001. The fire situation in Central African Republic. Int. Forest Fire News 25.
