Bush thickening and indigenous woody plants as a source of renewable energy

Surplus woody plants in areas where there is bush thickening present an opportunity to harvest the wood as bio-fuel. The health of the ecosystem and rangeland restoration must, however, always be prioritised during any tree harvesting for bio-fuel. In South Africa, indigenous woody plants are a prominent feature of the savannah, the largest of the vegetation biomes in South Africa and the Southern African sub-continent.

Several recommendations can be made in the interests of ecological sustainability and for maintaining long-term stability. These are of value to landowners affected by bush thickening, as well as government decision-makers and non-governmental organisations (NGOs) involved in solving the problems associated with the bush thickening.

Recommendations:

objectives of tree-thinning operations must be clearly identified prior to the harvesting operation
the threshold value in terms of tree density that can be supported in a specific rainfall region without adversely affecting the grass layer must be determined prior to the harvesting operation. Harvesting of woody plant s should be done only in areas exceeding this threshold value
emphasis should be on selective harvesting, during which larger trees are retained and smaller trees and shrubs are harvested, preferably of the problem tree species
most woody plants will regrow again after cutting. While this may be seen as beneficial in the sense of a renewable resource, it is general ly considered undesirable from a restoration point of view. It is recommended than an appropriate and ecologically safe arboricide be used to treat cut stumps after harvesting
as new seedlings might re-establish in thinned savannah areas, a state worse than the original thickened area may develop if left unattended. Post-treatment management such as a fire or a limited treatment with an appropriate arboricide may be required
the bush thickening problem cannot be solved if its causes are not addressed. The most important aspect here is stocking rates of livestock and game. Landowners must comply with prescribed stocking rates and adequate rest of the herbaceous layer