AN ASSESSMENT OF BIODIVERSITY IN THE REKAWA, USSANGODA AND KALAMETIYA INLAND COASTAL ECOSYSTEMS IN SOUTHERN SRI LANKA

The survey was carried out to document the status of inland biodiversity in the Rekawa,Ussangoda and Kalametiya area along the Southern coastal zone of Sri Lanka. Thesurvey extended from October 2002 - March 2003 (6 months). A reconnaissance surveyof the inland areas was conducted, prior to the regular field sampling, in order to selectrepresentative sampling sites within the Ruk area. Eight sites were selected for regularfield sampling at fortnightly intervals, and the plants and animals of the area weresurveyed in a scientific manner, using appropriate sampling techniques.The survey area harbours a variety of natural and man-made vegetationlhabitat types,including both terrestrial and wetland systems. A total of 287 plant species belonging to222 genera under 94 families were documented from the above inland vegetationlhabitattypes of the Ruk area. Several sub types of Mangroves, based mainly on floristics, couldbe found in the RUK area. These include the Lumnitzera dominated stands (Rekawa),Ceriops dominated stands (Rekawa), Avicennia dominated stands (Rekawa), Mixedstands (Rekawa, Kahanda), Excoecaria dominated stands (between Lunawa andKalametiya) and Sonneratia dominated stands (Kalametiya, Malpeththawa). It isinteresting to note that some mangrove stands are represented by only a single species.A total of 328 species of vertebrates were recorded from the RUK area, of which 14species (4%) are endemic, while 27 species (8%) are nationally threatened. Thevertebrates include 52 species of fish, 17 species of amphibians, 49 species of reptiles,184 species of birds, and 26 species of mammals. The invertebrates include 72 species ofcolorful butterflies, 25 spec.es of terrestrial molluscs an": 9 species of aquatic molluscs.Three beach stretches that are important turtle nesting sites, eleven birding hotspots andthree bird roosting sites were identified within the RUK area.The study area has been identified for major development initiatives, under the SouthernDevelopment Programme of the Government of Sri Lanka. Therefore, the relevantconservation agencies should take steps to ensure that, biodiversity conservation concernsare adequately addressed in specific developmental activities planned for the area.

EXTRACTION PATTERN OF SOIL MOISTURE IN BARE SOIL, TEA PLANTATION AND SOIL COVERED WITH FOREST SPECIES (Alstonia macrophytla wall)

The present study conducted at the research farm, Faculty of Agriculture, University ofRuhuna, Mapalana and adjacent site of well established tea plantation from January toJuly 2003, to assess the moisture extraction patterns under tea (Camellia sinensis L.) andforest speices (Alostonia macrophylla wall) compared to bare soilDiviner 2000 is used to assess the soil moisture in different sites. The experiment wasconducted in two sites, viz well managed tea plantation and an experimental site whereAlstonia macrophylla wall is planted, and bare spots were kept randomlyThe soil under tea was loamy sand with bulk density of lBgcm" in surface layers whichincrease with the depth. The soil under forest species was silt loam with a bulk density of1.4gcm-3 in surface layers. Bulk density of bare soil was highly varied with an average of1.49gcm-3. A thick laterite layer was found in 40-5Ocm layer in tea soil and 50-60cmdepth in forest and bare soils. The results revealed that the water holding capacity of teasoil is high by about 16% compared to that of bare soil and water-holding capacity offorest soil is low by 8% compared to bare soil.According to the moisture extraction pattern of soils, somewhat highest retentioncapacity was in bare land followed by tea soil and then forest soil. The probable reasonfor this may be high evapotranspiration rate from tea plantation and forest species. Themoisture retention of the tea plantation is higher than the forest soil, due to the highevapotranspiration by forest speciesThe rate of moisture depletion is remarkably high in forest soil with an average of4.8mmlday constituting 60% increment over bare soil evaporation. Soil moisturedepletion rate of the soil under tea is about 4.2mmlday, which is 40% higher comparedthat to the bare soil evaporation. Well-established canopy cover of the tea plantationappeared to be a good barrier to reduce surface evaporationParameters like porosity, soil texture, soil temperature, rainfall, wind speed and rootdistribution pattern appeared to have an influence on the soil moisture depletion