CO2 concentration and flux near ground in marsh of the Sanjiang Plain of northeast China

The objective of this work was to characterize CO2 concentration and flux within and above a marsh plant canopy at heights 0.5, 1.0 and 1.5 m. Soil and air temperature, wind speed, net radiation and soil heat flux were also measured simultaneously. The seasonal changes in CO2 concentration show that the minimum CO2 concentration occurred in the fruiting period and mature date, and both of their minimum values were 314 μmol/mol. This illustrates that CO2 consumed by photosynthesis was stable during the period. The flux of CO2 can be thought as a turbulent diffusion phenomenon. By micrometeorological methods, the diurnal CO2 fluxes were measured in the flowering period, fruiting period, early mature date, late mature date and yellow-ripe stage. Their values were -0.18, 38.15, 23.13, 10.9 and 4.91 μmol/mol respectively.