HR: 0800h
AN: B51C-0956    [Abstracts]
TI: Effects of Future Climate Shifts on CO2 Exchange of a Grassland Ecosystem
AU: * Hsieh, C
EM: hsieh@ntu.edu.tw
AF: National Taiwan University, Department of Bioenvironmental Syatems Engineering, Taipei, 10673 Taiwan
AB: Increases in atmospheric CO2 concentration not only affects climate variables such as precipitation, water vapor concentration, and air temperature, but also affects intrinsic ecosystem physiological properties such as the maximum carboxylation capacity and stomatal conductance. De-convolving these two effects remains uncertain in biosphere-atmosphere water and carbon cycling. Using a simplified analytical net ecosystem CO2 exchange (NEE) model, tested with recently collected flux measurements in a humid grassland ecosystem in Ireland, we assess how much projected climate shifts affect net canopy photosynthesis (A) without physiological adjustments and contrast those findings with physiological adjustments already reported for several grassland ecosystems. Our analysis suggests that the intrinsic grassland ecosystem physiological adjustment of A is about forty five times more important than the resulting climatic forcing shifts from the IS92a scenario (and a double of atmospheric CO2 concentration). Implications to afforestation policy and future experimental efforts to quantify the carbon sink from humid grassland ecosystems are also discussed.
DE: 1833 Hydroclimatology
DE: 0315 Biosphere/atmosphere interactions
DE: 0634 Measurement and standards
SC: Biogeosciences [B]
MN: 2004 AGU Fall Meeting