in Fig.1a). During January to June for 181 days, average soil CO2 concentrations at the depths of 5 cm and 20 cm in mixed deciduous forest were 1,543.9±728.1 μmol mol-1 (with variation of 47.2%, n=17,157) and 3,918.4±1,524.6 μmol mol-1 (variation of 38.9%, n = 12,926), respectively. In dry dipterocarp forest, we found that average soil CO2 concentrations at the depths of 5 cm and 20 cm were 1,826.6± 1,140.7 μmol mol-1 (with variation of 62.4%, n=15,627) and 2,766.2±1,386.1 μmol mol-1 (variation of 50.1%, n=15,627), respectively (as shown in Table 1). B. Environmental parameters in the Forests In t h i s study, we measured s o i l moisture, soil temperature, air temperature and rainfall as seasonal scales (Fig.1c-e) which were used for assessing soil respiration (Rs) afterwards. The results show that the total precipitation during January to June for 181 days in mixed deciduous forest was 349 mm (n=338) and dry dipterocarp forest was 427 mm (n=267). The rain events influenced the dynamics of their soil moistures and temperatures afterwards.In mixed deciduous forest, average soil volumetric moisture at depths of 5 cm was 20.8±6.9% (variation of 33.2%, n=17,298). The average temperatures in soil at depths of 5 cm and atmosphere were 24.8±2.3°C (variation of 9.3%, n=17,157) and 25.9±4.5°C (variation of 17.4%, n=17,376), respectively. In dry dipterocarp forest, we found that the average soil volumetric moisture content at depths of 5 cm was 29.6±5.8% (variation of 19.7%, n=15,315). C. Soil Respirations (Rs) and Their Contributions to Ecosystem Respirations (Re) Assessing CO2 emissions using soil CO2 profile probes had been validated by comparing with the closed chamber method. There was no statistically significant difference between both methods 8. In this study, soil CO2 effluxes (or soil respiration rates) were reported with 15-minute intervals (Fig.1b). During January to June, soil CO2 effluxes in two forests was significantly different (p<0.05, n=11,845). However dynamics of soil CO2 efflux at the both sites coincided with dynamics of their soil CO2 concentration, soil moisture, temperature in soil and atmosphere, and rainfall. In mixed deciduous forest at MKL site and dry dipterocarp forest at DFR site, the average soil CO2 effluxes were 4.8±2.3 μmol m-2 s-1 (variation of 46.7%, n=12,919) and 1.9±0.8 μmol m-2 s-1 (variation of 42.3%, n=15,626), respectively (Table 1). Their accumulative soil CO2 emissions were 6.6 and 2.6 kg CO2m-2 y-1, respectively. Their ecosystem respirations (Re) were 9.4 and 5.9 kg CO2 m-2 y-1 therefore, the soil respirations (Rs) accounted for 70.9% and 44.6% of the Re, respectively. In addition, Rs in mixed deciduous forest contributed higher to Re than Rs in dry dipterocarp forest of about 2.6 times. This may indicate more active soil and forest floor processes including a rapid turnover of carbon in mixed deciduous forest compared to dry dipterocarp forest. Proceedings of the International Conference on Climate Change, Biodiversity and Ecosystem Services for the 155 Sustainable Development Goals (SDGs): Policy and Practice 27-29 June 2016, Cha-am, Phetchaburi, Thailand
Proceedings of International Conference on Climate Change, Biodiversity and Ecosystem Services for the Sustainable Development Goals : Policy and Practice 27-29 June 2016 at the Sirindhorn International Environmental Park, Cha-am, Phetchaburi, Thailand
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