This chapter presents the current state and change in the forest cover and the landuse pattern of Sri Lanka including trees outside forest areas. This information provides the basis for policy and management decisions that support sustenance of forest resources in Sri Lanka.
Sri Lanka is bestowed with many natural resources like limestone, graphite, minerals, sands, gems, phosphates, and clay. About fourteen percent (0.55 million ha) of land is arable, fifteen percent under permanent crops, seven percent under permanent pastures, thirty two percent under forests and woodland, and the rest 32% is under other uses. The main agricultural products are rice, sugarcane, grains, pulses, oilseed, roots, spices, tea, rubber, and coconuts.
Similar to some tropical countries, the forests in Sri Lanka have lost more than sixty percent of their crown cover (from over 84% in 1881 to about 24% in 1992) during past two decades. Future prospects are also not very bright unless special care is taken to conserve and develop remaining forest areas. Most of the information in this chapter is based on the satellite imageries and other information collected between 1991 and 1993 for "1994" assessment of its forest resources. This chapter starts with the general landuse pattern and then focuses on the natural forests and finally presents some information on the Trees Outside Forests (TOF) in Sri Lanka.
FRMP, 1995 (Figure 1) broadly indicates that about 35 % of land is under some form of agriculture, about 32% under natural forests and forest plantations, about 24 % under TOF, and the remaining 9% is under other uses (Table 4 at Annex)
Fig. 1. Landuse in Sri Lanka
The natural forests of Sri Lanka are currently classified into eight types; Lowland Mesophyllous Evergreen Dipterocarp Forests, Low Land Mesophyllous Evergreen Mixed Rain Forests, Lower Montane Notophyllous Dipterocarp Rain Forests, Lower Montane Notophyllous Evergreen Mixed Rain Forests, Upper Montane Microphyllous Evergreen Dipterocarp Rain Forests, Upper Montane Microphyllous Evergreen Mixed Rain Forests, Low Land Semi-Deciduous Forests, and Low Land Semi-Deciduous Wood Land / Thorn Shrub.
Lowland Mesophyllous Evergreen Dipterocarp Forests
This forest type is common in wet zone on elevations up to 900 M. The main species are Dipterocarpus hispidus, Doona congestiflora, Doona macrophylla, Shorea oblongifolia, Canarium zeylanicum, Palaquium petiolare, Mesua ferrea, Doona affinis, Doona disticha, Anisophyllea cinnamomoides, Bhesa ceylanica, Calophyllum thwaitesii, Chaetocarpus castanocarpus, Cullenia zeylanica, Dillenia (Wormia) triquetra, Myristica dactyloides, Syzygium firmum, Syzygium makul, Garcinia hermonii, Xylopia championii, Hopea juncunda, Schumacheria castanefolia, Timonius jambosella, Agrostistachys hookeri, Desmos elegans, Uncaris elliptica, Cannarus championii, Dalbergia pseudo-sisoo, Freycinetia pycnophylla, Ficus diversiformis, Psychotria sarmentosa, Gaertnera veginans, Lasianthus strigosus, Apama siliquosa, Litsea longifolia, Acrotrema spp. Neurocalyx spp. Acranthera coylanica, Schizostigma hirsutum, and species of Zingiberaceae family.
Lowland Mesophyllous Evergreen Mixed Rain Forests
This forest type is widespread in intermediate zone at or below 900 M elevation. The main species are Mangifera zeylanica, Pometia eximia, Artocarpus nobilis, Filicum decipiens, Turpinia malabarica, Rejoua dichotoma, Annamirta cocculus, Artabotrys uncinatus, Paramignya monophylla, Anodendron manubriatum, Entada spp. Pothos scandens Micromelium ceylanicum, Entada sp. Pothos scanden Micromelum ceylanicum, Goniothalamus spp. Dracaena thwaitesii, Ophiorrhiza mungos.
Lower Montane Notophyllous Dipterocarp Rain Forests
This forest type is common in the wet zone, especially on the southern encampment of the wilderness at an elevation between 900 to 1525 M. The main species are Doona gardneri, Doona zeylanica, Stemonoporus cordifolius, Stemonoporusj latisepalum, Stemonoporus acuminatus, Cryptocarya wightiana, Syzygium aqueum, Myristica dactyloides, Meliosma simplicifolia, Mappia ovata, Acronychia pedunculata, Hortonia floribunda, Wormia triquetra, Memecylon gardneri, Euonymus walkeri, Chloranthus glaber, Chassalia ambigua, Lindsaea sp.
Lower Montane Notophyllous Evergreen Mixed Rain Forests
This forest type is common at an elevation ranging between 900 M to 1370 M. The main species are Eleaeocarpus glandulifer, Myristica dactyloides, Semecarpus nigro-viridis, Cryptocarya wightiana, Palaquium hinmolpedde, Aglaia congylos, Calophyllum acidus, Fahrenheltia spp, Pygeum zeylanicum, Bhesa montana, Gordonia ceylanica, Nothopegia beddomei, Hortonia floribunda Elaeagnus latifolia, Asparagus falcatus, Freycinetia walkeri, Fagraea ceilanica, Pothos remotiflorus Rauvolfia densiflora, Agrostichachys coriacea, Strobilanthes spp. Hedyotis spp. Scutellaria, Pogostemon, Impatiens spp.
Upper Montane Microphyllous Evergreen Dipterocarp Rain Forests
Such forests are widespread in the southern escampment above 1525 M. The main species are Stemonoporus rigidus, Stemonoporus cordifolius, Stemonoporus gardneri, Garcinia echinocarpa, Alphonsea coriacea, Gordonia spp., Palaquium rubiginosum, Syzygium spp., Mastixia sp., Cinnamomum ovalifolium, Semecarpus spp., Agrostistachys coriacea, Strobilanthes spp. Indocalamus, Hedyotis, Psychotria, Lasianthus Leucocodon reticulatum, Kendrickia walkeri Impatiens spp., Sonerila spp., Hymenophyllaceae, Orchidaceae, Bryophyta and Hepatophyta.
Upper Montane Microphyllous Evergreen Mixed Rain Forests
These forests are common at elevations above 1370 M. The main species are Calophyllum walkeri, Palaquium rubiginosum, Calophyllum trapezifolium, Cinnamomum ovalifolium, Garcinia echinocarpa, Neolitsea fuscata, Michelia anilagirica, Syzygium rotundifolium, Gordonia speciosa, Gordonia ceylanica, Actinodaphne speciosa, Symplocos spp. Glochidion montanum, Microtropis ramiflora, Eugenia cyclophyllu, Actinodaphne speciosa, Symplocos spp. Glochidion montanum, Microtropis ramiflora, Eugenia cyclophyllum, Disporum leschenaultianum, Exacum walkeri, Lichenes, Hepatophyta, Bryophyta, Orchidaceae.
Low Land Semi-Deciduous Forests
This forest type is widespread in lowlands of the dry zone and consists mainly of deciduous species like Chloroxylon swietenia, Vitex pinnata, Grewia polygama, and Berrya cordifolia, evergreen species like Mainlkara hexandra, Alseodaphne semecarpifolia, Diospyros ebenum, Drypetes sepiaria, Lepisanthes tetraphylla, Eugenia breteata, Garcinia spicata, and Walsura piscidia, deciduous or semi-evergreen species like Diospyros ovalifolia, Cassia fistula, Mitragyna parvifolia, Dimorphocalyx glabellus, Ventilago maderaspatana, Derris scandens, Glycosmis pentaphylla, Phyllanthus polyphyllus, Croton laccifer, Polyalthia korinthii, and Stenosiphonium cordifolium, Barleria mysorense.
Low Land Semideciduous Wood Land / Thorn Shrub
These forests are found wide spread in the low land areas of Arid zones. The main species are Manilkara hexandra (evergreen dominant), Sapium insigne (deciduous), Sapindus emarginatus, Strychnos potatorum, Diospyros ferrea, Randia dumetorum, Dichrostachys cinerea, Flueggia leucopyrus, Carissa spinarum, Gymnosporia emarginata, Azima tetracantha, Memecylon umbellatum, Cassia auriculata, Cissus quadrangularis, Abrus praecatorius, Hugonia mystax, Sansevieria zeylanica, Aloe barbadensis, Vicoa indica, Eragrostis viscosa, and Dactylotsenium aegyptium
Legg and Jwell (1995) have done the last assessment of forest cover during 1992 and 1994 with the help of twenty three TM quadrant and two TM full scenes from NRSA, India, six TM quadrant and four full TM scenes from Thailand, twenty two IRS-1 LISS-2 images from NRSA, India and twenty SPOT XS from an International distributor in Europe. These images cover the period from July 25, 1991 to June 11, 1993. The draught condition, during early 1992, helped in providing good quality cloud-free imagery for the whole country during a short span of time. Topographic maps at 1:63,360 (1 inch = 1 mile) and 1:50,000 scale produced by Survey Department, Sri Lanka were used for digitizing, control and geometric corrections.
The "digital vegetation map" (Legg and Jwell, 1995) classifies the natural forest into modified eight categories (Low-land rain forest, Moist monsoon forest, Dry monsoon forest, Sub- montane forest, Montane forest, Mangrove, Riverine forest, and Sparse/Open forest) and the forest plantations into four categories based on their main species (Conifer, Eucalyptus, Teak, and Mahogany). The forest types or eco-floristic zones of Legg and Jwell (1995) are based on intersection of natural forest boundaries, elevation and rainfall. This classification roughly correspond to the main classification of natural forests by Greller and Balasubramanium (1980) but does not follow further sub-classifications suggested by them. The range of elevation and rainfall defines the boundaries of first four categories (Lowland rain forest, Moist monsoon forest, Dry monsoon forest, and Sub- montane forest) carved out of the closed natural forest (Table 5). The ground truthing (not a "statistical" checking) has indicated that the accuracy in case of closed canopy natural forest is about 90% and in case of sparse and open forest is about 75%.
The total forest cover excluding forest plantations is around 30.9 percent. District and climatic wise forest types or eco-floristic zones (Table 3) indicates that the percentage of closed-canopy natural forest areas to total land area (6.616 million ha) is 23.9 percent (Legg and Jwell, 1995) and that of sparse and open forests is about 7.0 percent. Further that the forest plantations span over an additional 1.3 percent of total land area in Sri Lanka.
Legg and Jwell (1995) develop estimate of changes in forest cover by comparing their figures for 1992 to 1994 with that from FAO/GOSL forest census of 1983. They consider only "dense forests" or "closed canopy" forests to provide a reliable indication of changes in forest cover (Table 6 at Annex). Their assessment indicates that Sri Lanka has lost its closed canopy cover from about 84 percent in 1881 to about 23.9 percent in 1992 due to conversion to other types of land use, such as human settlements, plantation crops, agriculture and shifting cultivation. Thirteen districts (Ampara, Anuradhapura, Badulla, Batticaloa, Gampaha, Hambantota, Kandy, Kilinochchi, Kurunegala, Moneragala, Polonnaruwa, Trincomalee and Vavuniya) have suffered loss of forest while the rest 10 districts (Colombo, Galle, Jaffna, Kalutara, Kegalle, Mannar, Matara, Mullaittivu, Puttalam, and Ratanpura districts) show increase in their forest cover. They also indicate that the remaining forests are mostly dry monsoon forests, sparse forests and fragments of tropical rain forests.
A comparison between percentage change in tree cover under homegardens and forests in different districts of Sri Lanka for the period between 1992 and 1983 (Table 7) drawn up with the help of coarse (3-meter) imagery demonstrates a clear relationship between them (Legg and Jwell, 1995). The relationship relates to increase in homegarden with decline in forests and decrease in homegardens with increase in forests (Fig. 2).
Fig. 2. Percentage change in Forest Cover and Homegardens between 1982 and 1992
Fig. 3. Expected Change in Area (percentage) during 1995 and 2000
Detailed information on "other tree resources" is not available to estimate changes. However, FSMP has attempted (Table 8 at Annex) to develop an indication (Fig.3) of changes in tree resources under other land uses (settlements, road sides, tea estate, rubber and tea coconut plantations) between 1995 and 2000.
Large-scale forest tree planting in Sri Lanka started in late 1950's and till December 1996 has covered about 135,052 ha of forest plantations, of which, about 87,000 ha belong to the Forest Department. The main plantation species are Teak, Eucalyptus (mainly Eucalyptus grandis), Pine (Pine caribaea) and Mahogany.
Most of the fuel wood (Eucalyptus camaldulensis, E. tereticornis and Acacias), miscellaneous hardwood and teak plantations are located in the dry zones of Sri Lanka. The Eucalyptus (mainly E. grandis, but also E. microcorys, E. globulus and E. robusta) and Pines (P. caribaea and P. patula) plantations are mostly in the upland and in the Galle and Ratanpura forest divisions. The Mahogany plantations are situated in Kurunegala and Kegalle civil districts.
Planting of Teak was stopped in 1926 due to adverse silvicultural reports and was resumed again in 1939 in patana (natural grassland). The Pinus caribaea was planted between 1965 and 1984 while Pinus patula was planted during 1966 to 1976 especially at higher altitudes. During the 1970s and 1980s, Eucalyptus camaldulensis and E. tereticornis were established extensively in the dry zone, together with an increasing proportion of Acacia auriculiformis and Margosa (Neem). The current emphasis is on indigenous hardwood like Teak and Margosa while planting of Pines is banned and Eucalyptus is being planted only on a very limited scale.
Legg and Jwell, (1995) estimated the total area (Table 9 at Annex) of all mature and well-established forest plantations at 72,340 ha (1.1 % of the total land area of the country or 4.6 % of the area under closed canopy natural forests). The area under plantations are being regularly revised by successive plantation inventories mainly for the development of Plantation Management Plans, for example, Conifers (15,600 ha), Eucalyptus (8,400 ha), and Teak (33,000 ha). Normal and not "rigorous statistical" ground truthing for the assessment of plantation areas indicates that accuracy is 80% for remotely sensed mature upland plantations (Conifers and Eucalyptus) and 60% for the low-land dry zone plantations (Teak and Eucalyptus).
In addition to the above, fuelwood plantations have been raised over 18,002 ha till 1992, of which about 5,000 ha are located in Tea Estates and Tobacco Companies lands. District wise breakdown of fuelwood plantations raised till 1992 is presented in Table 10 at Annex and for the period between 1993 to 1996 period (AR, 1993; AR, 1994; AR 1995; and AR 1996) in Table 11 at Annex. Trees planted on homesteads and farmers woodlot etc. under "Participatory Forestry" project are not included in these tables.
This section provides information on tree resources outside forest areas in Sri Lanka. It includes homegardens, plantations of Rubber and Coconut, and trees raised in tea estates, agriculture fields, and other locations.
FSMP (1995) provides an estimate of the area (858,490 ha) under homegardens in all the districts of Sri Lanka. However, due to coarse resolution (30 meter) the imagery has not provided very reliable estimates, particularly in sparse home gardens in the dry zone. Therefore accuracy is lower for sparse open canopy home gardens and higher for home gardens with continuous canopy cover. Further, there is a possibility of misclassification in districts with higher percentage of tea and rubber plantations. Similarly, Jwell (1995) provides area (Table 12 at Annex) of home gardens for only 20 districts but fails to give any information on their reliability. He, therefore, did not proceed further to assess the area of homegardens in rest of the four districts (Killnochchi, Jaffna, Mullaittivu and Mannar) of Sri Lanka. Difference in the two (Jwell and FSMP) sets of information is more at district level than at national level. Figure 2 indicates percentage change in tree cover in homegardens in different districts of Sri Lanka.
Plantations of Rubber and Coconut and "trees in tea estates" cover about 687, 000 ha and make significant contribution to wood and fuelwood production (Table 13 at Annex). International and national prices of rubber, coconut and tea directly impact the area under these crops in Sri Lanka and thus control area, age, planting and replanting of trees in such areas.
Currently, about one-third of the trees in Rubber plantations are mature and are more than 32 years of age. With current level of harvesting, an equitable distribution of trees among the six age classes (Table 14 at Annex) is expected by the end of this century. However, since 1995 the area of re-planting (Table 15 at Annex) has substantially declined from an average level of 5,000 ha per annum mainly due to adverse market conditions.
The Coconut production has recovered from past draught and has registered a small growth. Unlike rubber, most of the coconut production (66 percent) is consumed locally. The stand structure of coconut plantations (Table 16 at Annex) in terms of five age classes is more complex than Rubber plantations due to large (40%) number of trees in the mid age group (30 to 50 years) alone. Therefore, the Coconut plantations will take more time than rubber plantations to achieve an equitable distribution of trees among different age classes.
Like rubber, the area of planting and replanting (Table 17 at Annex) under coconut gets affected both by international and national market prices. The export prices have increased marginally but the domestic prices have increased by more than twenty six percent. The area under re-planting and new planting of coconut is therefore increasing but with a large variation in the annual rates of replanting of coconut.
The land under coconut continues to fragment under high demand of land from industrial, housing and other sectors. About 1000 hectare of land under coconut plantation is diverted to alternative uses every year. The maximum pressure of fragmentation is in the low-land districts like Gampha and Kalutara, which incidentally are the districts with the maximum land under rubber and coconut plantations.
During last few years, the trees in the tea estates have increased with the expansion of Tea estates mainly due to privatization and favorable tea prices (Table 18 at Annex).
Other tree resources (Table 19 at Annex) under "four perennials" (cinnamon, cocoa, coffee, and Palmyra) cover about 101, 600 ha, along roadside span over an area of about 1,540 ha. and in human settlements occupy another 27, 600 ha. of land. These trees also make substantial local contribution to the production of timber and fuelwood in Sri Lanka.
Trees outside Forest (TOF) provide about 1.951 million m3 of wood where as natural forest contribute only about 0.009 million m3 every year. Among TOF, the home gardens make maximum contribution of about 0.551 million m3 of sawn logs and 0.786 million m3 of poles per annum and the trees along roadside and settlements contribute the least (0.005 million m3) (Table 20 at Annex).
The natural forests, forest plantations and trees outside forests annually provide about 1456.2 m3 of industrial wood and sawn wood. In addition, these sources also contribute a total of about 9.871 million tones of bio-fuel (Table No.21 at Annex) every year in Sri Lanka.
Although, Sri Lanka is one of the geographically small countries in Asia yet, it supports the largest bio-diversity in its natural forests.
The bio-diversity at ecosystem level has been well studied and defined by different researchers (Chapman, 1947; De Rosayro 1950, Holmes, 1958a and 1958b; Koelmeyer, 1961, Andrews, 1964; Gaussen et al., 1975; Perrier, 1980; Greller and Balasubramanian, 1980; Greller and Balasubramanian, 1993, and Wijesinghe, 1993). Greller and Balasubramanium, 1993 follow Walter's (1985) "Zonobiome" and "Orobiome" vegetation classification to create eight forest zones (Table 2 at Annex), while Wijesinghe et al. (1993) follow boundaries of climatic zones to develop six bio-climatic zones (Table1 at Annex) for Sri Lanka.
The species level biodiversity has been less studied than the ecosystem biodiversity. Its biodiversity species gradient declines from wet zone to dry zone. The natural lowland tropical rain forest having the maximum level of floral diversity. About 30% angiosperms and 18% ferns are endemic. The wet zone forests possess the highest endemism (Liyanage, 1995). Table 22 lists the identified species of vascular plants, vertebrates and selected invertebrates, and number of endemic species that demonstrates the high level of biodiversity in Sri Lankan forests.
Researchers have invested least efforts to investigate biodiversity at genetic level, which is only limited to the economically important floral species (FSMP, 1995). Similarly there are very few studies on genetic diversity of fauna and are limited to large vertebrates like elephants and leopards.
Table 23 and Table 24 at Annex present the biodiversity of tropical wet evergreen forests over wet zone areas of Matara, Galle, Kalutara and Ratnapura districts. It indicates a total of 619 woody flora species, of which, 302 are endemic. It also reveals a high level of faunal diversity with 25 molluscs, 52 insects, 30 fishes, 30 amphibians, 50 reptiles, 111 birds and 25 mammalian species. Floral and faunal diversity as well as the hydrological importance of the 15 forests of protected area network under the Forest Department in the low country wet zone is presented in Table 25 at Annex. Table 26 at Annex lists additional 17 forest areas suggested by a study for inclusion in the conservation programme to protect their biodiversity and hydrological regime.
Government of Sri Lanka (GOSL) demonstrates a high level of commitment for biodiversity conservation and many forest areas that were traditionally under production have been brought under conservation. Table 27 at Annex provides past history of initiatives taken by GOSL to conserve biodiversity. The country has developed its National Conservation Strategy in 1988. High levels of biodiversity have attracted international conservation initiatives (Table 28 at Annex) and more than 11,000 ha forests are conserved under different conservation initiatives. GOSL is responsive to international environmental initiatives and has signed many agreements linked to biodiversity, climate change, endangered species, environmental modification, hazardous wastes, law of the sea, nuclear test ban, ozone layer protection, wetlands, whaling and marine life conservation.
Despite increasing population pressures, the Protected Area network has increased in number and extent at a fast rate during last two decades. About 13 conservation forests in the wet zone and the Knuckles conservation forest in the wet and intermediate zone have come under conservation. Currently PAs contain about 1,888,781 ha (Table 29 at Annex) which is about 28.5% (Table 29 at Annex) of the total area of the country.
The Forest Development (FD) manages about 56.5 percent of the area under PA network while another department of the government (Department of Wildlife Conservation "DWLC" administers the remaining area under PAs (43.5 percent). The Wildlife Institute of India is assisting DWLC in development of management plans and human resources for all the PAs under control of DWLC.
This chapter provides information on forest resources and biological diversity contained in the forests of Sri Lanka. Sri Lanka is a unique country of South Asia with maximum biodiversity per unit area, and large extent of home gardens. The country is attempting to meet its domestic wood requirement from home gardens and forest plantations rather than its natural forests. The main concerns for sustenance of its natural forests include deforestation, soil erosion, wildlife poaching and coastal degradation from mining activities and pollution.
