8. SOME AGROFORESTRY PRACTICES IN KENYA                   

8.11 Woodlots

Spatial arrangement

If an area is set aside more or less entirely for trees, such an arrangement is known as a woodlot. Vegetables or crops are often intercropped in the woodlot in the early stages of establishment, but with time wood production is the most important use.

In small-scale farming areas woodlots are often very small, 0.1 hectare or less. Large-scale farms may have woodlots of many hectares.

Figure 8.15 A good Eucalyptus woodlot

Areas where the practice is relevant

Woodlots are particularly relevant in areas where light-demanding crops are grown, e.g. in areas where maize or sugarcane are dominant crops. Woodlots are also relevant for meeting wood requirements near irrigation schemes. In coffee-growing areas they are only relevant on waste land that is not fit for other use. Otherwise it is better to intercrop trees and coffee, or use boundaries, etc., since the coffee will tolerate a certain amount of shade. Tea performs best in Kenya without too many intercropped trees, so woodlots are also relevant for those areas. The British American Tobacco Company has also promoted woodlot establishment in tobacco-growing areas in Kenya.

Poor land that cannot be used for anything but trees is primarily recommended for woodlots. In some areas, however, tree production may be as profitable as crop production, so it would be justifiable to plant a woodlot on good land where the trees will grow fast. In certain areas, e.g. Vihiga near Kisumu, some farmers have opted for tree growing as the major use of their small farms since the market for poles and other tree products is good. Such arrangements may be profitable, but of course they also make the family vulnerable as they will be economically dependent on market forces and middlemen.

When discussing the location of a woodlot, transport requirements must be borne in mind. The site for wood production for domestic use should preferably be near the house to reduce the burden of carrying firewood, for example. Such considerations may also lead to a decision to use better land for a woodlot rather than the poorest land which may be further away.

Establishment and spacing

Establishment can be from seedlings or by direct sowing of seed, depending on species. Acacia mearnsii can be directly sown, and so can eucalypts, but the latter are difficult as the seeds are very small. Raising seedlings may be a better option.

The initial spacing can be very dense: 0.5 by 0.5 m, or even less if there is a demand for thin poles, fito or firewood. Gradual thinning will then enable the trees to grow to the desired size, while at the same time small-dimension wood can be harvested.

Management aspects

Protection from livestock and fire is always important for young trees. Initial intercropping with crops or vegetables helps protection and weed control. Pruning and thinning must be continuous to produce good-quality poles and timber. If the trees compete with adjacent crops, deep ploughing or digging a trench 50-80 cm deep will reduce the penetration of tree roots into the rooting zone of the crop.

Species with good coppicing ability are preferable to eliminate the cost of repeated establishment. Short rotations (6-8 years on good sites) are recommended.

A natural woodlot requires maintenance through selective bush clearing and protection in the early stages.

Benefits

In woodlots the most fast-growing trees, e.g. Eucalyptus, can be used since the land is used entirely for trees and there is little need to worry about competition with crops. A high level of wood production for domestic or cash-income purposes can be achieved. Trees in woodlots can also be a good way of making some savings. The negative aspect is that land, which is normally scarce, is taken out of agricultural production.

Examples of species

Fast-growing and coppicing species are best, e.g. Eucalyptus spp., Acacia mearnsii, Markhamia lutea and Cassia siamea. Pinus patula can also be used although it hardly coppices. Cupressus lusitanica has been used, but due to problems with the cypress aphid it should not be encouraged at present. Casuarina spp. may be alternatives. Grevillea robusta can be used, but sometimes only the trees at the edge of the woodlot perform well, while trees in the interior are stunted due to competition and possibly allelopathic effects between the trees.