The effects of wildfires on soil and vegetation in selected forest reserves in the transitional zone of Ghana
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Date
2007-08-08
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Abstract
The effects of wildfire on soil and vegetation were evaluated in three forest reserves in the transitional zones of Ghana namely Afram Headwaters, Bosomkese and Worobong South Forest Reserves. These reserves are part of pilots reserves selected for the Wildfire Management Project being implemented by the Forestry Commission of Ghana. This research examined the response of the soil and vegetation following continuous wildfires for about 15 years.
Data from soils in burnt sites within each reserve were compared to that in an adjacent unburnt sites as well as comparing burnt and unburnt sites among the reserves.
Using standard laboratory procedures, both physical and chemical properties (soil texture, bulk density, pH, % organic carbon, total nitrogen, % organic matter, calcium, magnesium, potassium, phosphorus, base saturation and cation exchange capacity) were determined. Again surface organic layers and vegetation (pioneer and successional species) were also examined. .Results indicated a 100% loss of surface organic layers in the burnt site of Afram Headwaters and also a 74% and 4% loss in Worobong and Bosomkese Forest Reserves respectively.
Soil texture increased (P ≤ 0.05) significantly on burnt site compared to unburnt site with regards to sand, and silt with the exception of clay which declined on the burnt site at Afram Headwaters. However, there was no significant difference on burnt and unburnt sites with regards to texture and bulk density at both Bosomkese and Worobong South forest reserves.
Results presented suggest that wildfires can significantly increase chemical properties like soil pH, potassium, and cation exchange capacity. However, soil levels of organic matter and total nitrogen are reduced after wildfires.
Common pioneer species found within burnt and unburnt sites in reserves include; Griffonia simplicifolia, Celtis malbraedii and Khaya anthotica. Common successional species recorded include; Chromolaena odorata and Broussonatia papyverifera.
A better understanding of the role fire plays as a natural disturbance in our forests should allow for intelligent management of these important, yet rapidly vanishing ecosystems.
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A thesis submitted to the School of Graduate Studies Kwame Nkrumah University of Science and Technology, Kumasi in patial fulfilment of the requirement for the Master of Science degree In Agroforestry.