In-Situ CO 2 Partitioning Measurements in a Phragmites australis Wetland: Understanding Carbon Loss through Ecosystem Respiration

Common reed ( Phragmites australis ) is dominant vegetation of temperate coastal wetlands in northeast China. To studying the link between ecosystem respiration ( R eco ) and its influential factors, a multi-year in-situ experiment was carried out in a newly restored wetland during the growing seasons of 2012 to 2014. Total in-situ R eco was separated into soil microbial and belowground root respiration ( R s + r ) and plant respiration ( R plant ). The soil microbial respiration rate ( R s ) was isolated from R s + r , making it easier to understand each component of R eco . With the wetland restoration process, the seasonal average aboveground biomass (dry mass) increased from 411.5 g m −2 to 2048.1 g m −2 and the corresponding R eco increased from 751.78 mg CO 2 m −2 h −1 to 2612.41 mg CO 2 m −2 h −1 . R plant contributed averagely 69% ~ 71% to R eco on the whole seasonal scale and the plant activity was strongly seasonal. With 1 g of aboveground common reed biomass (dry weight), approximately 3.6 mg CO 2 would be produced per hour during the sprouting period while it could be as low as 0.3 mg CO 2 during plant senescence period. Inundation regime dominated the contribution of R s to R eco and the flooded contribution would lower the R s contribution to as low as 11%.