Ecosystem respiration in coastal tidal flats can be modelled from air temperature, plant biomass and inundation regime

Abstract. Ecosystem respiration contributes greatly to carbon emissions and losses in coastal wetlands. To gain a better understanding of gaseous carbon loss from a coastal wetland covered by seablite (Suaeda salsa Pall.) and to evaluate the influence of environmental factors on ecosystem respiration, a multi-year in-situ experiment was carried out during the growing season of 2012 through part of 2014. By partitioning total carbon dioxide (CO₂) flux into soil respiration (R_soil) and plant respiration (R_p), we found that during mid-summer, ecosystem CO₂ respiration rates (R_eco) were within the range of 844.5 to 1150.0 mg CO₂ m^−2 −1, while R_eco was as low as 31.7 to 110.8 mg CO₂ m⁻² h⁻¹ at the beginning and the end of growing seasons. Aboveground S. salsa plant material comprised 79.1 % of total biomass on average, and R_p dominated R_eco during inundated periods. It is estimated that 1 gram of soil-emergent S. salsa biomass (dry weight) could produce approximately 1.41 to 1.46 mg CO₂ per hour during mid-summer. When water level was below the soil surface, soil microbial and belowground root respiration (R_s+r) was exponentially correlated with air temperature. Based on our observation, an empirical model was developed to estimate system respiration of the S. salsa marsh in the Liaohe River Delta, Northeast China. This model can be applied for regional carbon budget estimation purposes from S. salsa wetlands throughout Northeast China.