Abstract: N₂O emission fluxes were measured using the technique of closed opaque chamber and gas chromatography system,in a field experiment carried out during three growing seasons in 2003-2005 on a tract of Calamagrostis angustifolia meadow and Carex lasiocarpa marsh.Results show that the influence of wetland plants on N₂O emission of the wetland ecosystem varied with their growing stage.Obviously plants participated in and promoted N₂O emission in the wetland.The N₂O emission flux from the soil-plant system of Calamagrostis angustifolia meadow was 1.58,2.09 and 2.34 times as high as the apparent flux from the soil of the system during the three growing seasons,respectively,while that from the system of Carex lasiocarpa marsh was 1.86,1.50 and 1.33 times as high the apparent flux from the soil of the system.The N₂O emission flux of Calamagrostis angustifolia meadow was higher than that of Carex lasiocarpa marsh in all the three growing seasons,which may be attributed to differences between the systems in soil physico-chemical properties and hydrological conditions.

Key words: the Sanjiang Plain, N₂O emission flux, Calamagrostis angustifolia meadow, Carex lasiocarpa marsh, wetland plant