| Budget Amount *help |
¥3,410,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
In Mongolia,grassland covers approximately 80% of the country and comprises a major part of East Asian grasslands. The plants live in a semi-arid climate,and have often suffered from droughts.Global climate models predict that future increases in atmospheric carbon dioxide (CO2) will cause significant drying in this region during summer,caused by increased temperature and potential evaporation. Studies have indicated that the grasslands respond sensitively to changes in climate,particularly to changes in precipitation. The objective of this study was to evaluate the quantitative dependence of photosynthetic production and ecosystem respiration on temperature,moisture,radiation,and plant biomass in a semi-arid grassland. Toward this aim,we measured CO2 fluxes using a dosed-chamber technique in a grassland in Mongolia and in an environmental control equipment in Tottori University. As a result,we found that (1) values of gross primary production (GPP) were linearly related to live aboveground biomass (AGB) enclosed by the chamber, (2) GPP/AGB fit well a rectangular hyperbolic light-response curve for all the study periods,but when the air and soil were dry,considerable reduction in GPP was observed, (3) the GPP/AGB ratio was also expressed as individual functions of air temperature,vapor pressure deficit,and volumetric soil water content,and (4) values of Reco were expressed well as a bivariate function of soil temperature and soil moisture near the soil surface.
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