The impacts of tree density on the physical and biological characteristics of planted Mangrove stands in Sri Lanka

Survival, growth, aboveground biomass production, belowground biomass production, sediment accretion, soil surface elevation dynamics, sediment carbon and C/N ratio, sediment N and P, sediment 13C and 15N, sediment texture and macrofauna community structure, were studied in experimental treatments planted with four different densities (6.96, 3.26, 1.93 and 0.95 seedlings m-2) of the mangrove Rhizophora mucronata in Palakuda, Puttalam Lagoon, Sri Lanka. The first three parameters were also studied at a replicated experiment at Rekawa Lagoon, Sri Lanka. For both Palakuda (1,171days) and Rekawa (702 days) sites, the highest tree density (6.96 seedlings m-2) showed significantly higher % survival: means (±S.E.) of 93.4 (± 1.1) and 91.2 (± 1.38) respectively. The measures of individual trees (tree height, stem diameter, number of leaves, leaf area, number of branches, number of prop roots ) did not differ among treatments (p>0.05) for both sites. In contrast, the aboveground biomass responded significantly to planting density with higher plantation densities equating to greater biomass: 10772 ± 24 and 9904 ± 18.1g dry weight m-2 for Palakuda (1,171days) and Rekawa (702 days) respectively. The belowground biomass at Palakuda (1370 days) varied significantly between the densities with the highest belowground biomass (105.41 ± 6.98 g m-2) in the highest tree density. The same tree density had the highest numbers of fine roots m-2 for efficient absorption of nutrients. Higher tree densities accumulated more N in their sediments while the sediment phosphate was not different between the densities. Sediment ‰ 13C, ‰ 15N and C/N ratios ranged between -16.41 to -14.58, 2.80 to 2.40 and 9.32 to 7.85 respectively and were independent of the planting density. The 13C values indicated a potential mix of seagrass C and mangrove C in sediments of the treatments; the highest tree density (6.96 seedlings m-2) had significantly higher % sediment carbon (0.68 ± 0.04) compared with the unplanted controls (0.46 ± 0.05). Rates of surface accretion were 13.0 (± 1.3), 10.5 (± 0.9), 8.4 (± 0.3), 6.9 (± 0.5) and 5.7 (± 0.3) mm year-1 at planting densities of 6.96, 3.26, 1.93, 0.95, and 0 (unplanted control) seedlings m-2 respectively, showing highly significant differences among treatments. Mean (± SE) rates of surface elevation change were much lower than rates of accretion at 2.8 (± 0.2), 1.6 (± 0.1), 1.1(± 0.2), 0.6 (± 0.2) and -0.3 (± 0.1) mm year-1 for 6.96, 3.26, 1.93, 0.95, and 0 seedlings m-2, respectively. The community structure of the sediment macrofauna was unchanged between the treatments; that is likely to be the result of unchanged sediment texture and unavailability of mangrove derived carbon as the major food source. This study demonstrated the role of higher mangrove densities in enhancing the rates of sediment accretion and surface elevation processes that may be crucial in mangrove ecosystems' adaptation to sea-level rise. There was no evidence that increasing plant density evoked a trade-off with growth and survival of the planted trees during their early 1171 days of growth. While these potential processes need further research, the enhanced survival at high densities suggests the potential to use high plantation densities to help mitigate sea-level rise effects by encouraging positive sediment surface elevation. Higher biomass production in higher densities would also help faster sequestration of atmospheric carbon dioxide.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

The impacts of tree density on the physical and biological characteristics of planted Mangrove stands in Sri Lanka

Survival, growth, aboveground biomass production, belowground biomass production, sediment accretion, soil surface elevation dynamics, sediment carbon and C/N ratio, sediment N and P, sediment 13C and 15N, sediment texture and macrofauna community structure, were studied in experimental treatments planted with four different densities (6.96, 3.26, 1.93 and 0.95 seedlings m-2) of the mangrove Rhizophora mucronata in Palakuda, Puttalam Lagoon, Sri Lanka. The first three parameters were also studied at a replicated experiment at Rekawa Lagoon, Sri Lanka. For both Palakuda (1,171days) and Rekawa (702 days) sites, the highest tree density (6.96 seedlings m-2) showed significantly higher % survival: means (±S.E.) of 93.4 (± 1.1) and 91.2 (± 1.38) respectively. The measures of individual trees (tree height, stem diameter, number of leaves, leaf area, number of branches, number of prop roots ) did not differ among treatments (p>0.05) for both sites. In contrast, the aboveground biomass responded significantly to planting density with higher plantation densities equating to greater biomass: 10772 ± 24 and 9904 ± 18.1g dry weight m-2 for Palakuda (1,171days) and Rekawa (702 days) respectively. The belowground biomass at Palakuda (1370 days) varied significantly between the densities with the highest belowground biomass (105.41 ± 6.98 g m-2) in the highest tree density. The same tree density had the highest numbers of fine roots m-2 for efficient absorption of nutrients. Higher tree densities accumulated more N in their sediments while the sediment phosphate was not different between the densities. Sediment ‰ 13C, ‰ 15N and C/N ratios ranged between -16.41 to -14.58, 2.80 to 2.40 and 9.32 to 7.85 respectively and were independent of the planting density. The 13C values indicated a potential mix of seagrass C and mangrove C in sediments of the treatments; the highest tree density (6.96 seedlings m-2) had significantly higher % sediment carbon (0.68 ± 0.04) compared with the unplanted controls (0.46 ± 0.05). Rates of surface accretion were 13.0 (± 1.3), 10.5 (± 0.9), 8.4 (± 0.3), 6.9 (± 0.5) and 5.7 (± 0.3) mm year-1 at planting densities of 6.96, 3.26, 1.93, 0.95, and 0 (unplanted control) seedlings m-2 respectively, showing highly significant differences among treatments. Mean (± SE) rates of surface elevation change were much lower than rates of accretion at 2.8 (± 0.2), 1.6 (± 0.1), 1.1(± 0.2), 0.6 (± 0.2) and -0.3 (± 0.1) mm year-1 for 6.96, 3.26, 1.93, 0.95, and 0 seedlings m-2, respectively. The community structure of the sediment macrofauna was unchanged between the treatments; that is likely to be the result of unchanged sediment texture and unavailability of mangrove derived carbon as the major food source. This study demonstrated the role of higher mangrove densities in enhancing the rates of sediment accretion and surface elevation processes that may be crucial in mangrove ecosystems’ adaptation to sea-level rise. There was no evidence that increasing plant density evoked a trade-off with growth and survival of the planted trees during their early 1171 days of growth. While these potential processes need further research, the enhanced survival at high densities suggests the potential to use high plantation densities to help mitigate sea-level rise effects by encouraging positive sediment surface elevation. Higher biomass production in higher densities would also help faster sequestration of atmospheric carbon dioxide

INVESTIGATION OF VASE LIFE PACKAGE ON Codiaeum Variegatum CUT DECORATIVE SHOOTS

Croton is one of the exportable type foliage species in Sri Lanka. However,wilting of the leaves is a major problem raised in the export of these foliagespecies. In order to full fill the demand in world market, it is essential toovercome such problems.In this study, seven experiments were conducted at Green Farms (Pvt) Ltd.Marawila, to maintain the vase life of Codiaeum varigatum cv. 'Batik','Pictum', and 'gold star' cut decorative shoots and to retain their exportquality characters. Sugar (0, 1, 2, 4 & 5%), NiCh (250, 500, 750 &1000ppm), combination of sugar (2%) + KMn04 2ppm and glycerol (1, 5 and10%) were tested as treatments (vase solutions) in separate experiments.Treatments were arranged in complete randomized design with 3 replicateseach. Data were analyzed using SAS statistical method with analysis ofvariances. Mean separation was done using LSD on parametric procedures.Croton had ability to maintain vase life up to 3 weeks in preliminary studies.To comparison of different packing methods for vase life of croton, wetpaper packing showed higher vase life and higher leaf freshness for croton.Sugar treatments applied to "Pictum" and "Gold star" were maintained 21days of vase life. "Batik" showed only 17 days vase life (C.V. =7.750323).NiCh gave 18 days of vase life for "Batik" (CV = 11.04419) however it isharmful to human. According to the re-cutting & water changes, 4 dayscutting interval and 2 days water change was the best. Combination ofsucrose & KMn04 was maintained vase life vase life up to 14 days.Combination of Sucrose 2% + KMn04 2 ppm & Cotton plug was bestamong all sugar concentrations (C.V. = 10.90617). For this could maintainexport quality up to 19 days. "Pictum" & "Gold Star" were tolerant cultivars.Pure glycerol gave negative effects. All dilute glycerol concentrations (1, 5and 10%) were good post harvest treatments. Among those, 5% couldmaintain export quality of "Batik" cuttings up to 20 days. Combination ofwax + KMn04 + sucrose treatment gave negative effect. Pure wax withcommercial preservatives did not enhance the quality.

VASE LIFE STUDIES ON Dracaena reflexa CUT DECORATIVE SHOOTS

Wilting and color change of Dracaena leaves are major post harvestproblems in exportation. This study is an attempt to overcome these problemsand to improve vase life of Dracaena cut stems. Experiments were done atGreen Farms Ltd. Marawila to investigate post harvest handling of Dracaenareflexa to maintain export quality and freshness. Series of experiments wereconducted to investigate management practices; effect of glycerol solution(pure glycerol in 1,3 & 5hrs); effect of immersing one hour (using KMn04 2,5 & 10pmm); effect of sucrose solution (2, 5 & 10%); effect of KMn04 (2, 5& lOppm) for cultivars of Dracaena reflexa "Reflex a Green", "Song ofJamaica" and "Song of India". Treatments were arranged in completerandomized design with 4 replicates each. Data were analyzed using SASstatistical programme with analysis of variances. Mean separation was doneusing LSD on parametric procedures.The results revealed that wilting, color change and rotting, of Dracaenareflexa cultivars were not significantly affected by post harvest solutions ofKMn04 and sucrose compared to the control (tap water). However, pureglycerol (dipped for 1hr) and tap water maintained vase life of "Song ofJamaica" for 21days. Damaged cuttings showed Erwinia infection after 10-12days during vase period (CV = 05.628813). Results in general show avoidinginjury to specimens, and this helps to maintain the quality of the products.Many infections can be avoided by keeping the specimens dry. Experimentsproved that maximum vase life of Dracaena cuttings could be achieved bymaintaining proper management practices and sanitation conditions in a coldroom.

The impacts of shrimp farming on land-use and carbon storage around Puttalam lagoon, Sri Lanka

The expansion of shrimp aquaculture in Sri Lanka over the past three decades has dramatically changed the coastal landscape, in particular by converting mangrove forests. The current study quantified these impacts in the Puttalam lagoon, an area of the country that has experienced some of the most destructive development. Land use change was analysed using a multi-temporal set of aerial and satellite images taken in 1992/1994 (aerial photographs), 2007 (SPOT 5) and 2012 (Pleiades). The area of shrimp farms increased by 2 777% over this 19-year period, with salt pans expanding by 60%. Mangroves declined in area by 34% and coconut groves increased by 17%. Because of problems with disease many intensive shrimp farms are abandoned after a few years, leaving denuded and unproductive landscapes; here a large majority of farms (90% of the total area of shrimp aquaculture) were found to be abandoned. The loss of carbon sequestration and storage services caused by this unsustainable recent history of shrimp farming was calculated as one measure of environmental impact. The documented land use changes in Puttalam lagoon resulted in an estimated net carbon loss of 191 584 tC. This was mainly due to conversion of mangroves to shrimp farms, making up 75.5% of the total carbon loss. These results demonstrate the scale of environmental degradation caused by intensive shrimp farming in the study area, and highlight the need for an entirely new aquaculture model in Sri Lanka

LEARNStat: A Network Traffic Monitoring Utility

Developments in Information and Communication Technology have created many new applications, which require a large amount of bandwidth for proper application usage. However, international bandwidth is an expensive resource especially in this part of the world. Therefore, enterprises that use the Internet for business always need to efficiently use the bandwidth. Knowing the current (and past) usage is an important requirement in estimating the bandwidth requirement of a corporate network. The information of the composition of the use of the bandwidth by application, user group, etc. will help an administrator to efficiently manage it. Existing tools for network traffic monitoring are not capable of providing the above information. This paper examines some of the popular network monitoring tools that are widely used in the Internet community. The paper also presents the solution developed by the authors, i.e. LEARNStat, to monitor and analyze network traffic

Impact of collagen type X deficiency on bone fracture healing

published_or_final_versionBiochemistryDoctoralDoctor of Philosoph

Software-defined service networking: runtime sharing with functional and performance differentiation in multi-tenant cloud applications

Abstract not available

Depression and psychological distress in patients with chronic renal failure: Prevalence and associated factors in a rural district in Sri Lanka

Objective: Chronic Kidney Disease (CKD) is known to adversely affect mental health. The study was aimed at estimating the prevalence of depression and psychological distress and the associated factors among CKD patients living in Anuradhapura, a rural district in Sri Lanka. Method: A community-based, cross-sectional study included a representative sample of 1174 CKD patients, drawn proportionately from all registered patients in all 19 Medical Officer of Health areas in the district of Anuradhapura. Trained paramedical staff visited the households and administered the locally validated Centre for Epidemiologic Studies Depression Scale and General Health Questionnaire–12 to screen for depression and psychological distress. Information related to associated factors was obtained through an interviewer-administered questionnaire. Results: A total of 1118 CKD patients participated, with a response rate of 95.2%. The mean age was 58.3 (SD 10.8) years. 62.7% of participants were males. The majority of participants was in CKD stage 4 (58.3%). The screening revealed that 75.0% (95% CI 72.5–77.5) of participants were psychologically distressed while 65.2% (95%CI 62.4–68.0) were found to be depressed. Multiple logistic regression analysis revealed advanced age, unemployment and poor health related quality of life contributed significantly to both depression and psychological distress. Conclusion: Depression and psychological distress were significant in this community. Policymakers should consider the likely high prevalence of psychological distress and depression among CKD patients as well as the need for specific mental health services to confirm diagnosis and initiate effective management. Identified associated factors should be used to identify targeted preventative interventions.</p