Regarding the use of indigenous trees as timber plantation subjects, it is really only in its infancy in southern Africa. As you quite correctly pointed out, the Portuguese did plant considerable quantities of kiaat in Mozambique which are probably not yet ready for harvesting. The main problem is that for woodland species (kiaat, Rhodesian teak), growth rate is slow and the economics of growing such long-term timber species are seldom favourable. They have to be grown under optimal climatic conditions and on deep, sandy soils to allow for maximum growth rates. For those two species, South Africa is not well suited.

Moving on to forest species, we have one major hurdle to overcome when trying to grow them in a plantation situation. As you know, almost all the important timbers from our forests (Podocarpus spp., Ocotea bullata, Olea capensis) are climax species which have to germinate and develop in the shade and protection of other pioneer species. When we attempt to plant these desirable timber species in the open, in the same way as we do pines and gum, they struggle and rarely ever develop the tall, straight boles essential for the production of high-quality timber. The only way around this problem is to first plant a 'nurse' plantation of, for example (I hate to say it!) pines, or an indigenous equivalent such as Rhus chirindensis or Trema orientalis and then, a couple of years later, interplant with the desired timber species which will then have the protection of the nurse trees and, just as importantly, the competion which will force the timber species to grow tall and straight. This, however, would be an expensive process and probably unviable economically.

The other valuable southern African timber species which has been tested by the ex-Department of Forestry is Khaya nyasica (now K. anthotheca). Several trial blocks of this species have been planted on various stations in Mpumalanga and around Tzaneen but reports highlight problems with insect damage to the growing tip which cause premature branching. I would have thought some preventative spraying would be in order, or at least some corrective pruning, but they seem to have trashed that species because of this problem. Khaya does have the advantage of not requiring pioneer crops, providing that they are planted closely enough to one another. But this is one of the few timber species from the subregion which could be a viable proposition if they would be prepared to pay it a bit more attention.

Getting away from timber, there is also a great potential for the cultivation of indigenous trees (and other plants) for the production of medicinal use. There is a large list of indigenous trees and shrubs which are being exploited to the brink of extinction by traditional healers and their gatherers and the one way of perhaps saving these species, and make some money at the same time, is to produce them under plantation or orchard conditions. For forest species though, the same initial establishment problems as outlined above will be present.

By John Burrows, Director - Buffelskloof Nature Reserve