Abstract: By coupling the seasonal variation of leaf area index (LAI) with the synchronous chamber-based measurement of leaf net photosynthesis (respiration) rate and soil CO2 flux, the ecosystem carbon exchange in a saline desert was estimated, and the results were used to verify the reliability of eddy covariance data. The annual total leaf biomass of the saline desert ecosystem was 51.30±5.56 g·m^-2, of which, more than 90.45% were contributed by Tamarix ramosissima. In the whole growth season, the LAI varied in single peak pattern, being 0.18-0.30 from the 30th of May to the 30th of September and peaked at the 197th day. The measurement of the carbon flux by eddy covariance method and chamber-based method showed that the net ecosystem carbon exchange had an obvious seasonal variation, which peaked in mid-July and had significant correlation with LAI (P<0.001). Through comparison, the daytime ecosystem carbon exchange from eddy covariance measurement was agreed well with that from chamberbased measurement, but the nighttime ecosystem carbon exchange from eddy covariance measurement was slightly underestimated, probably due to the weak turbulence during the night.

Key words: soil organic carbon, carbon stable isotope, Junggar Basin., soil inorganic carbon, δ¹³C value