CO₂ CONCENTRATION AND FLUX NEAR GROUND IN MARSH OF THE SANJIANG PLAIN OF NORTHEAST CHINA

Key words: 
• CO₂ concentration /
• gradient of CO₂ concentration /
• CO₂ flux /
• marsh /
• the Sanjiang Plain

Abstract: There is limited information available on CO₂ concentration and flux over marsh. The objective of this work was to characterize CO₂ concentration and flux within and above marsh plant (Cares lasiocarpa Ehrh. and C. pseudoucuaica F. Schm) canopy at heights 0.5, 1. 0 and 1. 5 m.CO₂ concentration was measured sequentially every 3 bars by using an infrared gas analyzer. Soil and air temperature, wind speed, net radiation and soil heat flux were also measured simultaneously. Extremely drily minimum and maximum CO₂ concentration rangal from 250 to 754 μmd/mol for the 4-year work. The typical minimum and maximum values ranged from 314 to 464 μmol/mol at the height of marsh plant (about 0.5 m) during the fruiting perioed and mature date. 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 peried, fruiting period, early mature date, late mature date and yellow-ripe stage. Their values were -0.18, 38. 15,24.13, 10.9 and 4.91 μmol/mol respectively.