Afforestation is the planting of trees for commercial purposes, usually on land supporting non-forest veld types, e.g. grassland or fynbos. This differs from reafforestation which is the restocking of existing forests and woodlands which have been depleted.

Less than 0,5% of South Africa is covered by indigenous forests. Owing to their slow growth and sensitivity to logging, these forests cannot supply the majority of our country's wood requirements. Additional fast-growing trees are planted to cater for the demand for wood products. Commercial forests, or plantations, cover 1,1% of South Africa.

COMMERCIAL AFFORESTATION IN SOUTH AFRICA
* Pines, originally from the N. Hemisphere, make up 51% of the total commercial afforestation (TCA) in SA and are mainly used for sawlogs, veneer and pulpwood.

* Gum trees from Australia make up 38,9% of the TCA and are used for poles, mining timber, paper pulp and charcoal.

* Black wattle from Tasmania makes up 9,5% of the TCA and is used for tannin, paper pulp, mining timber and charcoal.

* Other trees make up the final 0,6% of the TCA.

Only 16% of South Africa, mainly the wetter eastern parts, is climatically suited to afforestation. In many cases the climate is extremely favourable and local pines grow at two to three times the rate of those in Europe or North America, where they originated.

Alien tree species (e.g. pines and gums) used in local afforestation do well in South Africa because they are not attacked by the insect pests and plant diseases which affect the trees in their country of origin. Careful breeding has also improved the growth characteristics of the species used in commercial forestry resulting in higher yields of wood per hectare. Today South Africa exports close to 2 million tonnes of wood and wood products.

WOODLOTS AND AGROFORESTRY
The increasing demand for fuelwood and building material in rural areas has caused widespread deforestation of natural woodlands, riverine zones, and water catchments. To reduce this problem woodlots have been established at a number of villages throughout the country to supply fuelwood and poles. Many woodlots make use of wattle and gum trees and now cover a total area of roughly 14 000 ha in South Africa.

The incorporation of trees with crops, a system known as agroforestry, is one method of increasing fuelwood production that is gaining popularity in Third World countries. Trees grown amongst crops supply timber, nuts, fruit, and fodder for cattle. Appropriate species of trees enrich the soil, prevent erosion, retain water, and shield crops from damaging wind and excessive sunlight.

AFFORESTATION AND THE ENVIRONMENT
The supply of wood and wood products from afforested areas has prevented the over-exploitation and destruction of our indigenous forests. However, unwise planning and management of afforestation can lead to negative environmental impacts.

Habitats most severely affected by afforestation include wetlands, grassland, fynbos and indigenous forests. Good management, and planning that takes conservation of natural habitats into consideration, can overcome these problems, some of which are outlined below:

Wetlands: Plantations situated too close to wetlands and perennial streams, or in their catchments, leads to their eventual drying out as trees use large amounts of water. The endangered wattled crane is dependant on wetlands for breeding (see Enviro Facts "Wattled Crane").

Grasslands: These rich communities support a variety of animals, including threatened species such as oribis, Stanley bustards and blue swallows. Afforestation converts grasslands to plantations, and so these animals lose their `home' (see Enviro Facts "Blue Swallow").

Fynbos: this unique habitat of the western Cape is also seriously affected by the invasion of alien trees from plantations (see Enviro Facts "Fynbos").

Indigenous forests: When plantations next to indigenous forests are logged, trees may fall onto the forest margin and damage it. Once damaged, the forest margin can no longer protect the indigenous forest from fire. In addition, logging can destroy the diverse habitat where forest and grassland meet. The forest margin is an important food source for many forest animals, e.g. bushbucks shelter in the forest but feed mainly on the smaller plants in the forest margin.

River catchments: Trees use large amounts of water. Afforestation in water catchments thus reduces runoff and water availability for other uses (see Enviro Facts "River Catchments").

AFFORESTATION AND THE GREENHOUSE EFFECT
Trees absorb carbon dioxide (CO2) from the atmosphere during photosynthesis. It has been suggested that large scale afforestation could successfully absorb the CO2 generated by the burning of the fossil fuels, coal and oil. The vast areas of afforestation required to achieve this would result in many negative environmental impacts. From a local perspective, in the short term such afforestation would cause as much environmental destruction as global warming could in the long term.

A better approach would be to tackle this problem at its roots: reduce our reliance on fossil fuels and prevent deforestation of our natural forests. Fossil fuel combustion and deforestation together account for the majority of man-made CO2 releases (see Enviro Facts "Global Warming").

DID YOU KNOW?
* In South Africa alien commercial forests cover about 3,5 times the area (almost 1,2 million ha) covered by indigenous forests (330 000 ha).

* Fifty-one per cent of commercial plantations are found in the former Transvaal and Orange Free State, 38% in KwaZulu/Natal, and 11% in the three Cape provinces combined.

* Plantation forestry started in South Africa in about 1888.

FURTHER READING

TREES OF SOUTHERN AFRICA. Keith Coates Palgrave. Struik, Cape Town. 1988 Southern Cape

FORESTS AND TREES. F. Von Breytenbach. Government Printer, Pretoria. 1974.

HOW TO GROW YOUR OWN TREES. J.H. Scriba. and H.L. Gerber. Pamphlet 109, Branch Forestry, Dept. of Water Affairs and Forestry, Pretoria. 1973.

TREES IN URBAN AREAS. J. Voslos Jordaan. Pamphlet 108, Dept. Water Affairs and Forestry, Pretoria. 1973.

USEFUL ADDRESSES

Trees for Africa. P.O Box 2035, Gallo Manor, 2000. Tel.011-803 9750.

Forestry Branch, Dept. of Water Affairs and Forestry. Private Bag X313, Pretoria, 0001. Tel. 012-299 91117.

Faculty of Forestry. University of Stellenbosch, Stellenbosch, 7600. Tel. 02231-773318

Saasveld School of Forestry. P/Bag X 6531, George, 6530. Tel. 0441-711011