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Item Spatial distribution and dynamics of selected mangrove forests on the east and west coasts of Sri Lanka(Sri Lanka Journal of Aquatic Sciences, 2022) De Silva, W.; Perera, K.A.R.S.; Amarasinghe, M. D.The climate and edaphic characteristics primarily determine the spatial distribution and dynamics of mangrove forests. The present study was initiated to determine how species composition and structural characteristics vary along with climate and substrate salinity of six mangrove forests located on the west coast, i.e., Negombo estuary, Chilaw lagoon, and Malwathu oya estuary, and east coast, i.e., Batticaloa lagoon, Uppar lagoon, and Urani lagoon. The structural parameters in terms of tree height, basal area, biomass, and density were obtained to determine the vegetation structure of mangrove forests. The current study found that although the structure of mangrove communities of the two coasts does not differ significantly (P<0.05), plant diversity in mangrove areas on the west coast is significantly higher than that of the east coast mangroves. In contrast, the biomass accumulation in west coast mangroves is relatively lower than that of east coast. Tree height was found to influence the productivity in terms of biomass increment of mangrove forests under investigation. As such, our study suggests that regional variations in salinity, temperature, and rainfall primarily serve as drivers of variation in mangrove species composition and vegetation structure of mangrove forests along the coasts of Sri Lanka.Item Effect of vegetation structure on carbon assimilation capacity of mangrove ecosystems in the east coast of Sri Lanka(2014) Perera, K.A.R.S.; Amarasinghe, M.D.Item Human influence on structure of mangrove vegetation in Negombo estuary(Sri Lanka Association for Fisheries and Aquatic Resources, 1999) Perera, K.A.R.S.; Amarasinghe, M.D.Item Mangrove soils are superior carbon sinks: Evidence from Sri Lankan mangrove ecosystems(Sri Lanka Association for Fisheries and Aquatic Resources, 2015) Perera, K.A.R.S.; Amarasinghe, M.D.Mangroves are among the most carbon rich ecosystems in the tropics. Inundation with tides and land-based surface runoff leads to anaerobic soil conditions that are conducive for accumulation of partially decomposed organic carbon. Present study was conducted to assess quantitatively the capacity of mangrove soils in retaining organic carbon. Distribution of total organic carbon (TOC) in soils of mangrove ecosystems in Negombo, Chilaw, Kala Oya, Malwathu Oya, Uppar, Batticaloa and Rekawa lagoons/estuaries, that represent western eastern and southern coasts as well as wet and dry climatic zones of Sri Lanka, was determined by using soil samples taken along the water-land gradient at 0-15 cm, 15-30 cm and 30-45 cm depths. Dichromate oxidation followed by colorimetric measurements were used to determine the percentage TOC and TOC densities were calculated using bulk density and % TOC values. Except for Batticaloa and Uppar lagoons in the dry zone, relatively a high soil TOC contents were observed in the surface soil layers (0-15 cm depth). By and large, the area between 10-30 m from the shoreline retained the highest average TOC in all mangrove areas. The highest percentage TOC in Sri Lankan mangrove soils is found not at the surface layer (4.92 - 15.1 % at the surface – 15 cm depth), but the layer below it down to a depth of 30 m (5.31 – 9.87 % at 16 – 30 cm depth). Soil beneath 30 cm contained the lowest amount (3.05 – 8.34 % at 31 -45 cm depth). Average TOC density of surface soil was 0.066 - 0.145 g cm-3 and in it was higher in mangroves of wet and intermediate climatic zones than those in the dry zone. The carbon retention capacity of Sri Lankan mangrove soils therefore was calculated to range between 313 – 492 t ha-1 and the highest was found to occur in the wet zone while it was 414 t ha-1in the intermediate zone. Soils of mangroves in the dry zone retained approximately 361 t ha-1 .of organic carbon up to a depth of 45 cm. The TOC retained by the soils of mangrove areas in Sri Lanka can be estimated as 5816 x 103 t. Inundation frequencies and durations as well as other bio-physical factors may affect the magnitude of TOC in mangrove soils.Item Carbon retention capacity of two mangrove species, Bruguiera gymnorrhiza (L.) Lamk. and Lumnitzera racemosa Willd. in Negombo estuary, Sri Lanka(Faculty of Graduate Studies, University of Kelaniya, 2012) Perera, K.A.R.S.; Sumanadasa, W.A.; Amarasinghe, M.D.Carbon accumulation/sequestration by plants is a major function that contributes to removal of carbon dioxide from the atmosphere and capacity to perform it depends on the plant species and environmental conditions under which they live. Carbon retention by natural ecosystems such as mangroves therefore‚ is considered a crucial ecological service‚ and valued highly under the current global context of continued increase in greenhouse gas emission and associated climate change, on which marginal effort has hitherto been spared over its quantification. The Present study was conducted to characterize two true Sri Lankan mangrove species, i.e. Bruguiera gymnorrhiza (L.) and Lumnitzera racemosa Willd.,. with respect to their carbon retention capacity, and to develop allometric relationships between biomass of plant components and stem diameter at breast height (dbh) of the two species with a view to assisting quantification of carbon-sink function of mangrove ecosystems. Fourteen trees of B. gymnorrhiza, and ten trees of L. racemosa that represented the range of dbh distribution in the mangrove area at Kadolkele in Negombo estuary were selected, harvested and dry weights (biomass) were obtained of the components based on wet:dry weight. Organic carbon in samples taken from each plant component of the two species was determined using dichromate oxidation and colorimetry using spectrophotometer. Partitioning of biomass between above (A) and below (B) ground components is approximately 3:1, revealing that the pattern resembles more of that of terrestrial plants (A/B = 3.9-4.5) than mangrove species in higher latitudes (A/B = 2-3). A positive correlation (p<0.01) and non-linear relationship (linear log-log relationship) was revealed between dbh and biomass (component and total) of the two species and allometric equations were derived that could be used to quantify carbon-sink function of mangrove ecosystems comprised of these species and the potential of mangroves in carbon mitigation programmes with financial incentives for mangrove conservation. The average amount of carbon retained by an individual was 9.16 kg per tree and thus the total organic carbon retained by L. racemosa in the mangrove ecosystem in Kadolkele was 9.44 t/ha while that of B. gymnorrhiza, was 5.6 t/ha, despite its greater capacity of individual carbon retention (13.76 kg per tree) due to its relatively low density and basal area. L. racemosa contains higher percentage of carbon in the stems, branches and roots than B. gymnorrhiza revealing its superior contribution to carbon-sink function of mangrove ecosystems