Session 2.2 carbon stock and tree diversity sri lanka

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1. Carbon stock and tree diversity of dry zone homegardens in southern Sri Lanka Eskil Mattssona Madelene Ostwalda S.P. Nissankab a Division of Physical Resource Theory, Department of Energy and Environment, Chalmers University of Technology, Gothenburg, Sweden b Department of Crop Science, Faculty of Agriculture, University of Peradeniya, Sri Lanka World Congress of Agroforestry 2.2. Tropical homegardens: multifunctionality and benefits Feb 10, 2014 Delhi, India 2. Homegardens in Sri Lanka Traditionally important land use system 13 percent of total land area Provide multiple benefits offering fuelwood, timber, food and income (Kumar and Nair 2006; Pushpakumara et al. 2012) Ongoing developing programs providing free seeds, fertilizer and technical advice (Mattsson and Johansson, 2011) Colombo 3. (Mattsson et al. 2013) Homegardens in Sri Lanka above ground biomass (AGB) carbon stocks 4. Aims of study map and assess biophysical characteristics of Sri Lankan dry zone homegardens and implications for climate change mitigation and adaptation investigate the amount and pattern of AGB carbon, soil organic carbon (SOC) and tree diversity assess present soil fertility in homegarden and rainfed agriculture (chena) lands 5. Study area Beralihela Moneragala District - dry zone - wet zone - int. zone 6. Methodology Measurements of DBH, height and species frequency in small ( 0.2 ha), medium (0.40.8 ha) and large (>1 ha) homegardens (totally n = 45) Soil samples in homegardens (n=45) and chena lands (n=20). Reference samples in natural forests AGB carbon stock and soil organic matter estimation using allometric equations (Chave et al. 2005) and Walkley and Black method (Schumacher 2002) 7. Results AGB carbon stocks 0 5 10 15 20 25 30 35 AGBCarbonstock(MgCha-1) small homegardens (n=11) medium homegardens (n=27) large homegardens (n=7) mean (small+medium+large) 26 9 8 13 Mean in AGB Kandyan forest gardens: 87 Mg C ha-1 Mean in Dry monsoon forests: 106 Mg C ha-1 Mean in Open dry forests: 22 Mg C ha-1 (Mattsson et al. 2012) 8. Results soil organic carbon Soil organic carbon (%) Max Min Mean SE Range Mg C ha-1 Homegardens 010 cm 1.7 0.2 1.1 0.04 1.5 15.9 Homegardens 2030 cm 1.2 0.3 0.8 0.03 0.9 12.1 Chena 010 cm 1.4 0.6 0.9 0.05 0.8 14.2 Chena 2030 cm 1.1 0.4 0.7 0.04 0.7 10.4 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1986 2013 SoilOrganicCarbon(%) Change of soil organic carbon 1986 2013 Dry open forest Homegardens Chena 9. Results tree diversity Homegarden size Species Shannon Wiener index (SWI) Mean number of species ha-1 SETotal Mean Mean SE Range Small (0.2 ha) n=11 43 14.91 2.08 0.15 0.76 2.66 80 10.03 Medium (0.20.8 ha) n=27 58 15.52 2.07 0.09 1.08 3.01 23 2.13 Large (1.01.2 ha) n=7 37 15.57 1.94 0.16 1.52 2.60 15 1.78 All categories 73 15.38 2.05 0.07 0.76 3.01 36 4.65 10. Implications and needs large variety of AGB carbon stocks in measured dry-zone homegardens (156 tC/ha); less than wet zone homegardens (48 to 145 Mg C ha-1) Higher carbon stocks and tree diversity per unit area in small homegardens ( 0.2 ha) than medium (0-40.8 ha) and large (>1 ha) water accessibility improved could improve crop diversification, carbon density and food security soil fertility can be enhanced through awareness creation of agricultural technologies with local participation harmonization with climate mitigation schemes under existing or emerging developing programs. Potential trade-offs needs further attention and food security is greater priority for farmers. 11. www.focali.se www.siani.se