PHYSICAL FEATURES This narrow strip of undulating terrain consists of a series of ridges and valleys. It is drained by an intricate network of streams, which flow into the Gin Ganga on the southern boundary and Kalu Ganga, via the Napola Dola, Koskulana Ganga and Kudawa Ganga, on the northern boundary. The reserve lies within the transition zone of two important rock types characteristic of Sri Lanka. The south-western group consists of metasediments, charnokites and scapolite-bearing calc-granulites, while the highland group comprises khondalites of metamorphosed sediments and charnokites (Cooray, 1978). Mostsignificant is the presence of the Sinharaja Basic Zone, consisting of hornblende, pyriclasts, basic charnokites, pyroxene amphibolites and scapolite-bearing calc-granulites and blended with small amounts of quartzites, garnet-biotite gneisses and intermediate charnokites (Hapuarachi et al., 1964). This zone coincides with an aeromagnetic anomaly, which has probably contributed to the desilication process responsible for the gem fields in the area (Katz, 1972; Munasinghe and Dissanayake, 1980). Soils, which largely belong to the red-yellow podzolic group, are well-drained and show very little accumulation of organic matter. This characteristic is attributed to a combination of favourable climatic conditions, a diverse soil microflora effecting rapid breakdown of organic matter into constituent nutrients, and accelerated uptake and recycling of nutrients by the trees. Clear-felling of the forest, where most of the nutrients are locked up, therefore renders the soil impoverished of essential nutrients and incapable of supporting sustained commercial forestry or agriculture (Forest Department, 1986). Information on soil profiles and soil microfungi are given in Zoysa and Raheem (1987).

CLIMATE Based on meteorological records gathered from in and around Sinharaja over the last 60 years, annual rainfall has ranged from 3614mm to 5006mm and temperatures from 19°C to 34°C (Zoysa and Raheem, 1987). Most precipitation emanates from the south-west monsoons during May-July and the north-east monsoons during November-January. Conditions are dry in February.

VEGETATION Two main types of forest can be recognised. Remnants of Dipterocarpus forest occur in valleys and on their lower slopes, with hora D. zeylanicus and bu hora D. hispidus present in almost pure stands. Secondary forest and scrub occur where the original forest cover has been removed by shifting cultivation and in other places the forest has been replaced by rubber and tea plantations (Rosayro, 1954). Mesua-Doona (Shorea) forest, the climax vegetation over most of the reserve, covers the middle and upper slopes above 500m (Rosayro, 1942) or above 335m as suggested by Gunatilleke and Gunatilleke (1985). Garcinia hermonii followed by Xylopia championii invariably dominate the understorey tree stratum, a range of species dominate the subcanopy and na Mesua nagassarium usually predominates in the canopy layer (Gunatilleke and Gunatilleke, 1985). Details about the structure and composition of the vegetation are summarised by Zoysa and Raheem (1987). Of Sri Lanka's 830 endemic species, 217 trees and woody climbers are found in the lowland wet zone (Peeris, 1975). Of these, 139 (64%) have been recorded in Sinharaja (Gunatilleke and Gunatilleke, 1985), 16 of which are considered to be rare (Gunatilleke and Gunatilleke, 1981). Other rare endemics are the palm Loxococcus rupicola (R) and Atalantia rotundifolia, the latter being restricted to Sinhagala at 742m. Of 211 recorded species of trees and woody climbers, 40% have low population densities (less than or 10 or fewer individuals per 25ha) and 43% have restricted distributions, rendering them vulnerable to further encroachments into the reserve (Gunatilleke and Gunatilleke, 1981). A variety of plants of known benefit to man are present, of which palm kitul Caryota urens (for jaggery, a sugar substitute), wewal Calamus sp. (for cane), cardamom Elattaria ensal (as spice), Shorea sp. (for flour), dun Shorea sp. (for varnish and incense) and weniwal Coscinium fenestratum (for medicinal purposes) are used intensively by villagers. A list of 202 plants, together with their endemicity and uses is given in the draft conservation plan (Forest Department, 1985).

FAUNA An early account of the fauna is given by Baker (1937). Preliminary lists of the fauna (viz. mammals, birds, reptiles, amphibians, fishes and butterflies) have been compiled (March for Conservation, 1985) and are included in the draft conservation plan (ForestDepartment, 1985). Endemism is high, particularly for birds with 19 (95%) of 20 species endemic to Sri Lanka present. Endemism among mammals and butterflies is also greater than 50%. Threatened mammals are leopard Panthera pardus and Indian elephant Elephas maximus (E). The endemic purple-faced langur Presbytis senex is present. Birds considered to be endangered or rare (Hoffmann, 1984) are Sri Lanka wood pigeon Columba torringtoni, green-billed coucal Centropus chlororhynchus, Sri Lanka white-headed starling Sturnus senex, Sri Lanka blue magpie Cissa ornata, and ashy-headed babbler Garrulax cinereifrons, all of which are endemic, and red-faced malkoha Phaenicophaeus pyrrhocephalus. Of interest is the presence of Sri Lanka broad-billed roller Eurystomus orientalis irisi (I), sightings of which have decreased markedly in the last five years (Zoysa and Raheem, 1987). Of the reptiles and amphibia, python Python molurus is vulnerable and a number of endemic species are likely to be threatened. Noteworthy species include Calotes liolepis, the rarest of all Agamids on the island, the rare rough-nose horned lizard Ceratophora aspera, restricted to part of Sri Lanka's wet zone, and Ramella palmata, a rare endemic microhylid (Zoysa and Raheem, 1987). Threatened freshwater fish are combtail Belontia signata (R), smooth-breasted snakehead Channa orientalis (R), black ruby barb Barbus nigrofasciatus (V), cherry barb Barbus titeya (V) and red-tail goby Sicydium halei (V), the conservation status of which is considered in Evans (1981). Of the 21 species of endemic butterfly, Sri Lanka rose Atrophaneura jophon is vulnerable (Collins and Morris, 1985). Sri Lankan five-bar sword Graphium antiphates ceylonicus, which is considered to be very rare, is not uncommon in Sinharaja at certain times of the year (J.N. Banks, pers. comm., 1986). Zoysa and Raheem (1987) comprehensively summarise what is known about the fauna.

CULTURAL HERITAGE The Sinharaja region has long featured in the legends and lore of the people of Sri Lanka. Its name, literally meaning lion (sinha) king (raja), perhaps refers to the original 'king-sized or royal forest of the Sinhalese', a people of the legendary 'lion-race' of Sri Lanka (Hoffmann, 1979), or to the home of a legendary lion of Sri Lanka.

LOCAL HUMAN POPULATION There are two villages within the south-west of the reserve, namely Warukandeniya and Kolonthotuwa, and about 52 families live in the north-western sector. At least 20 other settlements occur on the periphery, an unknown number of which have been illegally established on state land without approval from the relevant authorities. The total population is in excess of 5,000 people. Some land adjacent to the reserve is under private ownership, including small tea and rubber plantations. The extent to which local people are economically dependent on rain forest resources is variable but about 8% of households might be completely dependent (Silva, 1985).