5th Symposium on Fire and Forest Meteorology and the 2nd International Wildland Fire Ecology and Fire Management Congress

Tuesday, 18 November 2003: 4:00 PM
Causes and effects of wildfire in a West African tropical forest region
T. Kwesi Orgle, Ministry of Lands and Forestry, Accra, Ghana
Fire damage has become a more widespread and significant problem in West Africa since the devastating drought of 1982-83. During this period the Food and Agriculture Organisation (FAO) estimated that around 50% of the vegetation cover was destroyed. The subsequent annual fires have substantially altered the composition and structure of the Semi-deciduous forest. These forests and their associated genetic wealth, long-term productivity is under greatest threat from fire.

Fire is also known to reduce soil fertility by destroying the organic matter, which forms an important constituent of fertile soils. The effects of fire on soil fertility in the northern regions of Ghana were identified in the late 1970s. Farmers were already observing reducing soil fertility and associated yield reductions. This is now an increasing problem with reducing soil fertility within the transitional zone of West Africa.

Annual forest fires can result in changed species composition within the forest areas. It has been noted that burnt forests in the forest savanna transition zone do recover rapidly after fire, but that the growth is dominated by dense undergrowth that includes a high number of light demanding species. The more open canopy results in drier ground level biomass due to increased evaporation and with the addition of fallen burnt trees creates a large fuel source, making these forests more susceptible to future fires.

Forest fires are also linked to logging activity in West Africa. Evidence has been found to support the hypothesis that logging increases the incidence of fire. The vegetation of heavily logged forest a few years after logging ceased are more prone to fire. It is drier at ground level with more thin stems present and increased wind flow at ground level. Most of the important timber species in this region are not regenerating well in severely burnt areas. Fire is reducing the regeneration of economically important timber species, whilst the logging activity itself is increasing the incidence of fire.

The impact of fire is felt at the community level where encroachment by invasive species has been observed with them becoming dominant species within the farm-forest landscape. These have been observed to grow more vigorously after fire rapidly suppressing the growth of some tree seedlings. People link this change in vegetation to increased poverty and malnutrition due to reduced alternatives.

The impacts of forest fires and the resulting loss of forest have been linked to a reduction in rainfall and increased effects of the drying North-easterly winds from the Sahara (harmattan). A reduction in the area of coastal rainforests might have the additional effect of reducing the amount of rainfall heading inland to the drought prone countries of West Africa. With a rural economy mainly based on fire and agriculture it may be difficult to remove wildfire from the West African landscape in the foreseeable future.

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