Sri Lanka was once a land of tropical forests, nurtured by abundant, high temperatures and rainfall and long growth periods. However, over the last century much of the forest resource has been destroyed along with many of its material benefits. Deforestation has now seriously diminished the timber supplies, made soil less productive, water supply more erratic and floods more frequent and severe.
The area of natural forests has declined drastically during the last 100 years. With the decline of the natural forest, the main alternatives for meeting the present and future needs for wood are trees grown on non-forest land, and forest plantations. With the expanding population and economy, the demand for industrial forest products, logs, and fuelwood will continue to grow. At present, Sri Lanka is almost self-sufficient in most wood-based forest products, but imports appear to be increasing. Also, some of the wood supplies are being met from illicit fellings. Also the gap between demand and sustainable supply of roundwood will continue, which means that action needs to be taken now to meet future needs. If the supply of wood from home gardens and other non-forest lands will decline in the future, there is an even greater need for intensively managed forest plantations.
Forest plantations were established for the first time in the 1870s, although most of the planting has taken place since the 1950s. Within that period, about 89,000 ha of forest plantations of varying quality have been established. This area comprises some 5000 ha of mainly fuelwood plantations, which are under the control of tea estates and a tobacco company.
Forest plantations in Sri Lanka were mainly established using exotic species due to their faster growth rates over the indigenous species. Although the history of introducing exotic timber species goes back to 1870s, most of the planting has taken place since the 1950s. The idea of this exercise was to have an alternative timber resource to protect the existing natural forest and to rehabilitate the environmentally damaged areas within a short period of time.
Teak is popular all over the world due to its high quality timber with remarkable physical and mechanical properties. This is a light demanding species with large deciduous leaves. Harvesting can be started since 15-20 years for intermediate sizes. Mature timber can be obtained between 30-45 years depending on the site quality.
Teak was introduced to Sri Lanka in 17th century by Dutch. It was widely planted in dry and intermediate zones after 1950s. Although 45,335 ha of land have been utilized by the Forest Department for teak plantations, the effectively managed area might be less due to constraints such as wild elephants, illicit felling and encroachment. Although the most prominent type of teak plantations are monocultures, there are some mixtures such as with eucalypts and mahogany.
Mahogany is a large deciduous tree with an umbrella-shaped crown, frequently reaching height of over 30m and diameter at breast height of over 1.5m. This species is able to tolerate a wide range of environmental conditions.
Like teak, mahogany too have a long history in Sri Lanka. In 1840, mahogany was first planted in Sri Lanka in Jaffna as an avenue tree. At present about 4,500 ha of mahogany were maintained by the Forest Department mainly in the intermediate zone and low country wet zone in Sri Lanka. Realising the timber value of mahogany, recently private sectors has also started creating mahogany plantations at commercial level.
Most of the mahogany plantations established by the government become semi-natural forests due to the ignorance of management activities. The reason was that those plantations were established with other species such as jak which is not recommended for felling and the possible environmental problems that can be arisen due to felling. Therefore at present the most common mahogany supplier in Sri Lanka is the home gardens.
Different eucalypt species prefer different climatic conditions and have different growth rates. Eucalypts were introduced to Sri Lanka on trial basis in the late 18th century. After 1953, Forest Department established Eucalyptus grandis and E. microcorys plantations in the hill country Sri Lanka, especially in degraded lands for the rehabilitation. The other objectives were to obtain sawn timber, transmission poles, railway sleepers and fuel wood. Eucalyptus robusta are also planted in the hill country.
Eucalyptus camaldulensis and E. teriticornis are widely planted in the dry zone of Sri Lanka. These plantations were established after 1970. Both species indicate a slow growth rate when compared with the grandis and microcorys.
Eucalyptus toreliana plantations have mainly been established in the wet zone of Sri Lanka especially by the private sector.
Pine is the only conifer species planted in wide scale in Sri Lanka. Pinus caribaea (introduced in 1965) has mainly been planted in low country wet zone and P. patula (introduced in 1966) has been planted in up country. The main objective was to rehabilitate the degraded land. As a non-wood forest product, resin tapping was also suggested at that time.
However, growing pine in Sri Lanka created a dialogue over its unsuitability for the natural evidences. There were evidences such as drying out of streams, reduction of ground water level, no undergrowth and lack of animal diversity after planting pine. Therefore, Forest Department has taken a policy decision that new pine plantations would not be established again in Sri Lanka.
Although the species such as teak, eucalypt, pine and mahogany were the popular species at the time of plantation establishment in large scale, recently Alstonia macrophylla also became popular due to the ease of establishment and the fast growth rate. At present alstonia has been widely planted in Galle, Kalutara, Matara and Ratnapura districts by the Forest Department and also, a significant amount has been established by private companies (especially tea companies in their fallow lands).
Alstonia is preferably grown in wet zone in Sri Lanka not only as plantations, but also as avenues, blocks or individuals in homegradens.
A considerable amount of forest plantations have been established using other species such as Acacia, Cypresses, Khaya and Azadirachta indica (margosa). Out of these species, margosa (also known as neem) is the only local species which is growing well in the drier parts of the country. Among the private sector planters, Albizia odorotissma (albizia) and Melia dubia (lunumidella) are also becoming popular.