The history of cultivating trees in home gardens, social tree planting, protection and management of forests and appreciation of wildlife and the beauties of nature in Sri Lanka go back to over 25 centuries. In chronicles there are references to social tree planting practices, well-organized village communities, and home gardens planted with flowering and fruit bearing trees. Because of the age-old agroforestry tradition, numerous examples of agroforestry practices are found in all climatic zones of the country.
Today, the traditional knowledge of agroforestry is being developed and expanded with the objective of improving living standards of rural poor. A wide range of agroforestry systems is found in Sri Lanka and their characteristic features (Nanayakkara 1991) could be summarized as below:
Shifting cultivation is an age-old agroforestry system where forest and food crops are grown alternately in temporal sequence. The system is sustainable as long as there is a reasonably long fallow period (at least 15 years). However, with population growth and shrinking forest cover, the fallow period has shortened resulting in severe land degradation. In the Dry Zone, large tracts of forest were lost in the past due to uncontrolled shifting cultivation. Formerly, issuing of cultivation permits by the government regularized the shifting cultivation and in 1981 issuing of these permits was officially terminated. Today only few sporadic, illegal shifting cultivation activities are taking place in remote Dry Zone areas.
This agroforestry system was a modified form of the Burmese Taungya system. This system was practised especially to convert the degraded Dry Zone natural forests into teak plantations with participation of shifting cultivators in this scheme. Cultivators were provided an opportunity to grow agricultural crops over a three-year year period, while the farmers were also paid a monetary reward. Farmers formed cooperative societies and participated in the programme. This system has produced good results; almost all the best teak plantations established in the Dry Zone and Intermediate Zone have been raised under this scheme. Though this system was originally applied for teak, in later stages some Eucalyptus camaldulensis and E. tereticornis plantations were also raised. The shortcoming in this system has been the insecure land tenure for the cultivators; the system encouraged nomadism, which did not improve the life standard of cultivators.
Coconut is the most widely planted industrial tree crop in Sri Lanka. It covers about 25% of the total cultivated area on the island. A large number of tree crops such as teak and mahogany are grown in association with coconuts. Tea is the second largest industrial crop in the country and it is grown mainly in the central hill country and in wet southwest lowlands. A large number of leguminous and other shade trees are grown in this agroforestry system.
The fuelwood needs of tea estates, including the energy for tea processing and for the domestic needs of tea estate workers, are met with firewood species grown within this system. Rubber is the third largest industrial crop in the country and fruit trees are often intercropped with rubber. As the shade cast by rubber in the later stages of its rotation is dense, intercropping is fairly restricted. Pineapple and cocoa are grown in areas where rubber canopy is not too dense. Palmyrah palm (Borassus flabellifer), which is a multipurpose tree yielding many products inter-cultivated with cashew nut is another agroforestry system found in coastal areas of the Dry Zone and in semi-arid areas of northern and eastern districts.
Sloping agricultural land technology is also widely adopted in central hilly areas of the country. In this system hedgerows are grown along contour lines in sloping lands of abandoned tea areas, alternating with agriculture crops. Fuelwood species, such as Gliricidia sepium are commonly grown in hedgerows. Continuous mulching with pruned biomass from hedgerows improves soil conditions and reduces erosion.
Kandyan home garden system is an age-old traditional agroforestry system practised in the central hilly areas and in some other districts in the Wet Zone. This system is an ideal form of land use combining agriculture, forestry and livestock. Trees are grown in a multi-layer arrangement and mixed cropping of trees yielding timber, small wood, fuelwood, fodder, food, fruits, medicines together with crops yielding food and medicine is practised. Maximum utilization of space, both vertical and horizontal, is ensured in this system.
Since the 1980s the FD has started establishing partnerships with farmers in the rural areas in raising farmers’ woodlots. This system is practiced mainly in the Dry Zone and in drier sites in the central hilly areas. Relatively small blocks of degraded state lands (less than 0.1 ha) have been leased out to local farmers on a long-term lease basis. Seedlings of forest and horticulture species and technical advice are provided to the farmers free of charge by the FD. In this system, the farmer is entitled to harvest the final tree crop, leaving few mother trees in the plot. Farmers are also rewarded in the form of a food ration for successful establishment and maintenance of plantations.
Plantation forestry is considered to be of great value in relieving pressure from natural forests and, at the same time providing more uniform products as compared to natural forests.
The forest policy of 1929 emphasized increased wood production to ensure self-sufficiency and to allow also for some exports. In 1938, a policy of planting natural grasslands (patanas) was commenced and planting of exotic tree species such as pines and eucalypts in up-country, reflected the prevailing emphasis of the policy. The forest policy of 1953 emphasized timber and fuelwood production to meet the increasing demand and with this development some mechanized planting of wet and dry grasslands were carried out using Pinus caribaea.
Plantations of Eucalyptus grandis and E. microcorys as well as acacias were established at that time. Most of the Pinus caribaea plantations in the country were planted between 1965 and 1984. In latter part of the 1980s, with environmental concerns about monocultures, especially exotics, the planting of Pinus species virtually ceased.
In the Dry Zone, large scale planting of teak was carried out until the 1980s and since then the scale of planting has reduced because the successful establishment of teak depends on clearing and burning of natural forests, which is now regarded as undesirable.
During the 1970s and 1980s, Eucalyptus camaldulensis and E. tereticornis were established extensively in the Dry Zone, together with Acacia auriculiformis. These species were planted in a response to the concerns about a potential deficit in fuelwood supply. Some of these plantations were not successful due to damages by animals and fires.
One of the main forestry projects in the 1980s was the ADB-funded Community Forestry Project, under which the development of fuelwood plantations and agroforestry in five districts took place. During the same period, the International Development Agency (IDA) and the Finnish International Development Agency (FINNIDA) funded a Forest Resources Development Project and the FD established extensive commercial plantations under various rural development projects.
During the 1990s, under the Forestry Sector Development Project funded by the British Overseas Development Agency (ODA), UNDP/FAO and IDA, the FD established plantations of species such as acacias, mahogany as well as indigenous species. In 1993, the FD implemented an ADB-funded Participatory Forestry Project where emphasis was given to increasing wood production in home gardens, farmers’ woodlots, protective woodlots and public reserve lands. This work was carried out through participation of farmers.
Presently, the FD is implementing reforestation activities under the ADB-funded Forest Resources Management Project. The main species that is being planted in the Dry Zone is teak, while eucalypts are planted in the upcountry as commercial timbers. Planting efforts implemented directly by the FD are involved mostly in regeneration cutting areas of mature forest plantations, while afforestation of degraded areas is mostly implemented through local people's participation. Relatively large blocks of land of over 25 ha are leased out to private companies to establish commercial plantations, while farmer participation is sought in establishing plantations in smaller blocks of land.
The seeds of indigenous tree species, such as Terminalia arjuna (Roxb), Holoptelea integrifolia (Roxb), Terminalia belerica (Gaertn) Roxb, Madhuca longifolia (L), Diospyros ebenum (Koenig), Chloroxylon swietenia, Lagerstroemia speciosa (L), Pericopsis mooniana (Thw) are collected locally by farmers as well as by the FD. The FD also imports seeds of exotic species required for agroforestry and reforestation programmes. The FD supplies seedlings of many timber species to farmers from departmental nurseries. In addition, a large number of seedlings are produced and supplied from farmer nurseries, school nurseries and NGO nurseries that are supported with technical assistance by the FD. A Tree Seed Centre has been established in the FD, attached to the Forest Research Centre. The Seed Centre building and cold storage facilities have been constructed with assistance from the ADB.
National seed demand is calculated and seed procurement from local and foreign sources is planned accordingly. Priority is given to seed collection from seed orchards and seed production areas. Collected seeds are cleaned and dried in the sun until the seed weight remains constant. Small-scale seed collecting for special purposes is done when requested. Collected seeds are labelled and stored for future use. Seed testing is done for seed moisture, viability and germination. Certified and high-quality seed is dispatched to divisional staff as and when required. Seeds and planting materials of fruit trees and horticultural plants are supplied by the Agriculture Department through departmental and farmer nurseries.
Conservation of FGR necessarily involves management of the resources in the context of human use. Long-term conservation of genetic resources requires regeneration of representative populations. Indigenous tree species and populations are most efficiently maintained in situ through natural regeneration or by planting trees of local origin and of wide parentage.
Many important indigenous tree species such as Lumnitzera litoria and Carapa moluccencis are facing genetic degradation due to continuous removal of phenotypically better trees under the selective management system. Thus, some of the indigenous tree species are found at present only in natural habitats. Their natural regeneration is threatened due to various factors. The activities conducted by the Forest Department in relation to in situ conservation could be listed as:
• Strict protection of highly valued natural forests without permitting any kind of disturbance including harvesting (Knuckles Forest and Sinharaja area have been declared as strict conservation forests under the new categorization of forests).
• Development of separate management plans for important forests to ensure their conservation while obtaining essential services.
• Maintenance of a computerized environmental database – Environmental Information Management Systems (EIMS) that contains data e.g. on plant and animal species in the country.
• Implementation of Sinharaja, Knuckles and Mangrove Conservation projects.
• Maintenance of the Man and Biosphere (MAB) reserves.
• Buffer zone management in natural forests.
• National conservation review to assess the biodiversity of natural forests, which are 200 ha or more in extent. (The work in 33 natural forests in the Wet Zone has already been completed while the work in the Dry Zone will be done in the future).
• Development of forest plantations, homegardens and other agroforestry systems to meet the social needs, which can reduce the threats to natural forests.
• Identification of medicinal plant conservation areas in selected natural forests.
• Acquiring mangrove areas from local authorities to the FD, declaring them as conservation areas and preparing management plans for them.
• Conducting research on enrichment planting and related areas in degraded natural forests. Studying natural forests in terms of biodiversity, rarity and endemism.
• Research on natural regeneration and floral biology in the natural forests.
With respect to ex situ gene conservation, the following activities are being conducted by the Forest Department:
• Collection of germplasm of endangered species from their natural range and planting in blocks as genebanks.
• Collection of seeds of native species and establishment of plantations.
• Establishment of seed orchards to conserve superior germplasms.
• Vegetative propagation of valuable local species for genetic improvement.
• Importation of genetic materials of plantation species from other countries and planting them in the field either to broaden the genetic base of existing species or to introduce new species.
• Planting of medicinal plants in buffer zones of natural forests, home gardens, etc.
In addition to in situ and ex situ conservation measures taken by the FD under the Medicinal Plant Project, the Biodiversity Division of Ministry of Environment and Natural Resources is establishing Plant Sanctuaries, which is a form of ex situ conservation blocks for the conservation of indigenous tree species such as Pterocarpus santalinus, Lumnitzera litoria, Carapa moluccensis. This work is carried out in collaboration with the Faculty of Agriculture of the University of Ruhuna.
The choice of seed sources is one of the main factors affecting the establishment and productivity of tree plantations. During the pioneering years, there were hardly any scientific studies on provenance variation within species and species introductions were done in an ad hoc manner. The present practice of silvicultural provenance research provides a sound basis for selection of seed sources.
In the Dry Zone, the most important species for tree improvement research have been teak, eucalypts and acacias. Starting in 1941, the first teak trials examined the performance of five provenances originating from Burma as well as ‘local’ landraces that presumably originate from the old introductions from India (Vivekanandan 1977).
Eucalypts have been introduced into Sri Lanka since 1960s. Systematic evaluations and provenance trials have been conducted by the Research Division of the FD for e.g. Eucalyptus tereticornis, E. alba and E. camaldulensis (Vivekanandan 1979; Connelly 1990; Nikles 1992; Bandaratillake 1997); for a summary, see Appendix 1. As for acacias, A. auriculiformis and A. crassicarpa have shown promising performance in the Dry Zone.
• Acacias
During the 1980s there was a widespread interest in new species of phyllode acacias that were found in Australia. Acacia mangium was introduced into Sri Lanka in the 1980s and was planted on a trial basis on different sites in the Wet and Intermediate Zones. The FD, in close corporation with the Australian Tree Seed Centre embarked on the evaluation of several new species of acacias from different geographic locations in Australia (Weerawardane and Phillips 1991).
•
Eucalyptus
Eucalypts have been the principal species planted in the hill country, the most important species being E. grandis. During the early stages seeds have been imported from overseas, mainly from Australia and very little attention was paid to the seed origin. Over the years the best seed sources, even though their origins are unknown, have become adapted to the local conditions and have been performing well. In the 1980s a number of species cum provenances trials were initiated in a number of locations (Weerawardane and Phillips 1991; Vivekanandan 2002).
• Pines
During the 1970s, the Oxford Forestry Institute in cooperation with national forestry institutions initiated several international species cum provenance trials of tropical Pinus species in a number of countries in Asia, including Sri Lanka. The provenance trials of Pinus caribaea and Pinus oocarpa are of particular interest. These trials provide the basis for the large-scale establishment of plantations in degraded sites in the upland and in the low country Wet Zone.
