Browsing by Author "Perera, G.A.D."

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    Investigating Variation of Microbial Biomass in Plantation Forests with Age
    (Uva Wellassa University of Srilanka, 2011) Premetilake, M.M.S.N.; Rathnayake, R.R.; Kulasooriya, S.A.; Perera, G.A.D.
    Note: See the PDF Version Soil organic carbon is the basis of sustainable agriculture and is important for chemical, physical and biological fertility. Consequently, carbon soil fertility could be improved more via sequestering. The role of microorganisms is important for carbon sequestration in soil compared to other factors. Thus, by increasing the activity of microorganisms we can increase carbon sequestration and soil fertility. Plantation forests were originally established in Sri Lanka to provide industrial timber and fuel wood. There are also other uses such as wind protection, bee keeping and oil extraction and moreover they provide invaluable ecosystem services. At present, sites available for reforestation in Sri Lanka are generally poor in nutrients and fertilizer application is required for better growth of seedlings. A novel approach of research at the IFS is the application of beneficial microbial consortia as biofilm biofertilizers for sustainable agriculture (Seneviratne et al., 2011). These are low cost and are eco-friendly. The shifts in composition and function of the microbial community in response to different stages of forest regeneration play an important role in determining rates of C changes (loss or gain) in the soil (Plante at al., 2005). Hence the long term goal of this study is to produce biofilm bio fertilizer for forest plantations to improve their yields. This would be more beneficial, less expensive and have no detrimental effects to the ecosystems. The biofilm bio fertilizer will be prepared using the microorganisms that have the capability of sequestering more carbon than the others. In this process, identification of the microorganisms and the factors affecting them is a crucial component. There are no studies conducted on this regard in Sri Lankan plantation forests yet. In the current study we investigated how the microbial biomass carbon (MBC) varies in Eucalyptus grandis forests in Sri Lanka with their age. Improved Carbon sequestration in forests would deliver better yields and would assist in minimizing climate change and support in obtaining foreign currency via carbon trading.
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    Soil Organic Carbon and Interdependencies among Soil Physio-Chemical Parameters of Mangrove Dominated Ecosystem at Palakaimunai in Mannar Region, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2021) Dissanayake, D.D.M.O.; Jayasinghe, J.A.V.R.; Perera, G.A.D.; Kadupitiya, H.K.; Seneweera, S.; Ratnayake, R.R.
    Palakaimunai, positioned at North Western coast of Sri Lanka, has been shaped and influenced by oceanic, terrestrial and anthropogenic activities to varying extent. The natural vegetation in this deltatic system is dominated with mangroves with intermittently spreading saltmarsh patches at the foreground and littoral woodland species at the back. The extent which the mangroves in such seasonally dry tropical climates would provide sediment-grounds for soil carbon and other nutrients is yet to be revealed. Therefore, spatial variation of soil carbon and carbon fractions, and the associations of these to available nutrients in Palakaimunai mangals were examined in this study. Stratified random sampling adhering to 10 m × 10 m grids based on ArcGIS were laid and soil sampling (n=30) was done from the layer of 0-15 cm from surface. Samples were analyzed for available nitrate, phosphate and ammonium, microbial biomass carbon (MBC), permanganate oxidizable carbon (POC), water soluble carbon (WSC) and soil organic carbon (SOC), soil macro and micro nutrient cations. Principal component (PC) analysis and agglomerative hierarchical clustering based on geometric positioning under PCs revealed five clusters indendogram, despite there was a high spatial heterogeneity examined soil parameters over the area. Interdependencies were unreciprocated among pH (+) to SOC (-) and WSC (-) and ammonium (-) and zinc (-) to MBC (+). The samples in the clusters with the highest mean SOC content of 11.3%- 14.0% and was associated with low MBC (0.005% ± 0.007) , high POC (712.23 ± 6.97 mg/kg), high WSC (0. 15% - 0.16%) and high ammonium (14.2 ± 8.5 mg/kg) contents. Nevertheless, the samples in the cluster with the lowest SOC content of 1.99 ± 1.54 was found to be associated with the highest availability of nitrate (2.90 ± 0.78) and lowest of phosphate (14.98 ± 6.02 mg/kg) contents. These highest SOC contents were recorded at proximate substratum with Avicenia and Rhizophora species and within frequently saturated substratum. Simultaneously, low MBC content was related with the above prevailing aneroxic condition. Thereby, generalization over in-site SOC may not verify the carbon sink potentiality thus varied by geomorphological traits. Keywords: Blue carbon ecosystems; MBC; WSC; Cluster analysis; SOC