in Sri Lanka - Ministry of Environment

Present status of Lowland Wet Zone Flora of Sri LankaH. S. KathriarachchiDepartment of Plant Sciences, University of ColomboIntroductionSri Lanka has an outstanding biodiversity because of its tropical climate, soil, topographicalvariations, geographical location and its striking biogeographic history. Together with theWestern Ghats in India, Sri Lanka is considered as one of the 34 biodiversity hotspots inthe world because of the high degree of endemism in fauna and flora and serious amount ofhabitat loss (Ashton et al., 1997; Gunatilleke et al., 2004). The diverse array of ecosystems inSri Lanka harbors a wealth of plant species and they provide a habitat for many other speciesas yet undiscovered.Sri Lanka also has a diversity of climatic and floristic regions showing spatial variations in rainfall,altitude and soil. Lowland wet zone represents the area below 1,000 m in elevation, spreadingin the southwestern quarter of Sri Lanka (Figure 1), mainly in the Colombo, Gampaha, Kalutara,Galle, Matara, Kegalle districts and part of Ratnapura (Gunatilleke and Ashton, 1987b; Ministryof Forestry and Environment, 1999).Flora of the lowland wet zone of Sri Lanka is largely distributed in the tropical lowland rainforests- forests below 1,000 m altitude (Figure 1). These forests have an aseasonal wet climate andgenerally receive 2500 – 5000 mm of mean annual rain fall without prominent dry spells. Meanannual temperature is about 27 o C at sea level. The lowland wet zone forests are classified byde Rosayro (1950) as wet evergreen forest climax by Koelmeyer (1957) and Holmes (1956) aswet tropical evergreen forests . These forests are confined to 2.14% (141,506 ha) of the totalland area of Sri Lanka (Ministry of Forestry and Environment, 1999).SRIFigure. 1 Map showing the forests in the south-west of Sri Lanka. Blue = Fragmented lowlandrain forests remaining in Sri Lanka, Green = Montane rain forests, Brown = Intermediate zone forests,Yellow = Dry zone forests (Source: Somasekaram et al., 1997).175