Sri Lanka offers a great diversity of habitats, based upon physiography, soil types, and climatic variations. These geographical features have paved the way for a wide range of ecosystem diversities and a large number of floristic regions. Its geographic location close to Indian sub-continent has helped the migration of flora from Indo-Malayan, Afro-Madagascan and Afro-Arabo-Iranian floristic realms into the country via the land connections, (Cooray, 1984). The central mountainous region contains floristic elements with affinities to northern temperate regions, especially from the Himalayan. Of the fifteen floristic regions identified in country, thirteen fall in the wet and intermediate zones.
The varied physiography of mountains, hills and low land and high to moderate rainfall has aided the existence of this wide range of ecosystem diversity in less than half country's land area.
About 7 500 plant species constitute the flora of Sri Lanka. Flowering plants constituted about 3 360 species, belonged to 1 350 genera and 200 families. The flora contains by about 830 endemic species. The low-country wet zone and mountainous areas in Southwest harbour 90 percent of endemic species.
4.1 Medicinal plants
The rich diversity in flowering plants has produced large number of plants of immense economic value. Among them are medicinal plants, spices, food plants and ornamental plants. Over 600 species have been used as medicinal plants. A large number of herbs are used in the indigenous systems of medicine since Ayurveda is widely practised in the State. A list of these Forest Herbal Materials Utilised by the Ayurvedic Corporation of Sri Lanka is presented in Annex 1. The demand for medicinal plants for ayurvedic prescriptions and by pharmaceutical companies are also met largely from natural sources. The commercial level of extractions may further diminish the resources thus cause added hardships to rural women.
4.2 Plants for natural dyes
Different plant parts of numerous species have been used to obtain natural dyes for use in cloth dying, handicrafts, colouring food etc. Thus these plant resources contribute to the artistic heritage and economic security of the Sri Lankan community. A few examples are given in Annex 2.
4.3 Wild relatives of cultivated plants
A number of cultivated food plants have their wild relatives like Musa acuminata and Musa bilbisiana, Artocarpus heterophyllus (Jackfruit), A. Incisus (Breadfruit), Citrus, Mangifera zeylanica (etamba), and Yams. Among spices, black pepper, cardamom, cinnamon have their wild relatives in the wet zone forests. Among the crop plants, wild species of rice (Oryza rufipogon), Rhynchosia, Dunbaria, Viscosa (Wild relatives of Cajanus Cajan) have been recorded (Baldwin, 1991).
4.4 Forest types and forest bio-diversity
In Sri Lanka, habitat diversity has given rise to a corresponding wide range of forest types, as depicted below 7 types of forest types are recorded. (Box No. 1) Each forest area with unique climatic environment supports wide variety of trees species. These forest resources support various livelihood activities and access to food.
Well-known species of timber plants such as satin wood (Chloroxylon swietenia; Buruta) mahogany (Swietenia macrophylla) teak (Tectona grandis), ebony (Diospyros ebenum; Kaluwara), Nedun (Pericopsis mooniana) occur in the country. Rattan (Calamus sps.) Is represented by ten species, out of which eight are endemic in Sri Lanka. Besides, Aston et al (1997) have listed 250 plant species which yield timber, and are put to various uses by Sri Lankan rural men and women.
|Box. 1. Forest types in Sri Lanka|
High country elevation above 1 500 mm
Temp. about 15 Celsius, wet zone
Rainfall> 1 800 mm
S.W. and N.E. monsoons
S.W. and central region
Elevation 1 000–1 500 m
Temp. 15 Celsius-20 Celsius, wet and intermediate zones
Rainfall >1 800 mm
S.W. and N.E. monsoons
|Low land wet evergreen forest|
Low to mid-country
Temp. 15 Celsius-20 Celsius
Rainfall >2 500 mm
No moisture deficit period (S.W. and N.E. monsoons)
|Moist evergreen forest|
Below 1 000 m elevation
Dry zone; rainfall 1 800–2 500 mm
(N.E. monsoon pronounced dry spell of 3 months)
|Dry mixed evergreen forest|
Below 600 m elevation;
Dry and arid zones;
Rainfall 1 000–1 800 mm
(N.E. monsoon, pronounced dry spell of 3 months)
|Riverine dry forest|
Along river valleys and flood plains; below 600 m elevation,
Rainfall 1 000–1 800 mm
(N.E. monsoon pronounced dry spell of 3 months)
|Mangrove forest sheltered inter-tidal coastlines in combination with lagoons and mouths of rivers|
Besides legal or illegal logging, forested areas were encroached upon for chena cultivation in dry zone, put to fire for land clearance to establish small-scale tea plantations in mid-country area. This continuing feature led to loss of bio-diversity. The majority of people, who live in rural areas, often close to forests to meet their requirements through forest products. People especially women frequently visit the forests to pick up wild fruits, flowers, seeds, condiments, medicinal plants, plant parts for natural dyes, grasses for thatch and material to make household items. The diminishing forested area and its bio-diversity affect the poor and the landless, women in particular, since a part of their collection are sold in the village markets.
Since the colonial period, the natural flora has been under threat due to over-exploitation and disruptions in the natural ecosystem. Efforts are made to protect the representative flora in conservation areas.
4.5 Diversity in fauna
The country supports a high faunal diversity due to its wide-ranging variations in geophysical features and ecosystems. The extensive forested areas, and different vegetation types enable the existence of terrestrial, aquatic, and avian fauna. The fauna of Sri Lanka is as diverse as the flora. While sharing common features with the neighbouring subcontinent, the fauna exhibits very high endemism among the less mobile groups. With taxonomic revisions and descriptions of new species, the number of species in each group keeps changing.
4.5.i Loss of wildlife resources
Since the beginning of the colonial period, the wildlife had faced an ever-increasing onslaught. Earlier ethical restraints of the Sinhala people against destroying life had gradually been weakened. The phase of habitat destruction, which began with plantation and selective logging, continued in the form of forest clearance for new settlements and to meet timber requirements. These changes took a heavy toll of the wildlife, birds and many of the yet unrecorded smaller lifeforms. Elephants had been the worst affected. The elephant population which at the beginning of nineteenth century was estimated to be 12 000, came down to around 3 000 in the last decade of twentieth century (Baldwin, 1991). Earlier, the elephants were killed for protecting plantations and for sport, and later on poached for their ivory tusks.
Other animals were hunted for food, earlier mostly by tribal communities, now by other ethnic groups also. A list of animals hunted for food in Sri Lanka is presented in Annex 3. Strict regulations against all seasonal hunting and protection of wilderness areas are required to avoid further vulnerability and possible extinction in future.
4.6 Bio-diversity conservation
Sri Lanka has taken steps to ensure conservation of its bio-diversity while the farmer's efforts to conserve their basic natural resource inputs are also important.
4.6.i Biodiversity protected area network
Sri Lanka was covered with extensive forested tracts in early nineteenth century. Starting with the plantation era of late nineteenth century, the forest cover declined from 70 percent of land area in 1900 to around 30.8 percent by 1993. Various factors like land clearing for raising plantation crops, selective logging, chena cultivation, large irrigation schemes, new agricultural settlements, expanding human habitations and other developmental activities were responsible for this decline.
4.6.ii In situ conservation
Considering the sharp decline in forested area and loss of biological diversity, efforts are being made to conserve remnants of what once was a rich heritage. The conservation of biological diversity is under the jurisdiction of Forest Department (FD) and Department of Wildlife Conservation (DWLC). The conservation programmes include demarcation of protected areas to conserve flora, fauna and wildlife. Special conservation areas have been demarcated to provide protection to elephants, birds, mangroves, are coral reefs. The present network of protected areas is given below in Table 1.
|Table 1. Present network of protected areas|
|1.||Strict nature reserves||3|
|(Knuckles forest range, Ritigala forest)|
The Forest Department has proclaimed 41 biosphere reserves and 15 conservation forests. The Sinharaja Forest declared as a World Heritage site and also an International Biosphere Reserve, is a unique Evergreen Tropical Rain Forest for South Asia. It is located in the wet zone and harbours a large number of Gondwanaland relicts of flora and a large number of endemic plant and animal species.
4.6.iii Ex-situ conservation
Efforts exist in the form of botanical gardens, arboreta, seed banks, zoological gardens and aquaria. The foremost of the botanical gardens, Peradeniya Botanical Garden at Peradiniya near Kandy, was established in 1822. It has a line collection of 10 000 species of flowering plants and 1 179 species of other plant groups representing the national flora as well as those brought in from other countries. The Plant Genetic Resource Centre at Gonnoruwa is concentrating on the conservation of crop germplasm.
4.6.iv In-situ on-farm conservation
The traditional home gardens, numbering over 1.3 million in different agro-ecological zones, have played a key role in conserving a wide spectrum of germplasm of economically important plant species and prevented their possible extinction. Farm women have played a key role, first by identifying the economic value of such plants for food, medicine, spice, dyes etc. and later domesticating them. The women had accumulated a vast pool of knowledge of the flora, which evolved into a system of nomenclature, growth rhythms and utility value.
This system of in-situ on-farm should be expanded and further strengthened for the management biodiversity conservation. Women from rural areas and surviving tribal groups could be usefully involved in the process. Efforts in this direction have a sense of urgency to institutionalise the indigenous knowledge of natural resources.
4.6.v Institutional network
The Ministry of Environment has created a broad network of about 12 government institutions and NGOs to attend to various aspects of bio-diversity conservation and management. In consultation with these institutions, the Ministry of Forests and Environments prepared a comprehensive plan entitled “Biodiversity Conservation in Sri Lanka: A Framework for Action”, 1998.