CO sub(2), H sub(2)O Energy Exchange of an Inner Mongolia Steppe Ecosystem During a Dry and Wet Year

Potential of carbon dioxide (CO sub(2)), water (H sub(2)O) and energy exchange of an inner Mongolia steppe ecosystem during a dry and wet year was determined. An eddy covariance (EC) system was used to measure continuous CO sub(2) fluxes over the grassland. The observations indicated that the wet 2004 growing season had higher peak evaporation rate than did the 2005 drought season. It was found that the soil respiration was temperature dependent when the soil was under non-limiting soil moisture conditions. It was also indicated that as soil endured water stress, this response became accumulatively decoupled from soil temperature and even decreased at higher temperature. The results concluded that the CO sub(2) uptake power of the ecosystem and the possibility of developing a carbon sink mainly depended on the magnitude and timing of rainfall events associated with the phenological stage.