Effects of environmental conditions and aboveground biomass on CO budget in Phragmites australis wetland of Jiaozhou Bay, China.

Estuarial saline wetlands have been recognized as a vital role in CO cycling. However, insufficient attention has been paid to estimating CO fluxes from estuarial saline wetlands. In this study, the static chamber-gas chromatography (GC) method was used to quantify CO budget of an estuarial saline reed ( Phragmites australis) wetland in Jiaozhou Bay in Qingdao City of Shandong Province, China during the reed growing season (May to October) in 2014. The CO budget study involved net ecosystem CO exchange (NEE), ecosystem respiration (R) and gross primary production (GPP). Temporal variation in CO budget and the impact of air/soil temperature, illumination intensity and aboveground biomass exerted on CO budget were analyzed. Results indicated that the wetland was acting as a net sink of 1129.16 g/mduring the entire growing season. Moreover, the values of R and GPP were 1744.89 g/m and 2874.05 g/m, respectively; the ratio of R and GPP was 0.61. Diurnal and monthly patterns of CO budget varied significantly during the study period. R showed exponential relationships with air temperature and soil temperature at 5 cm, 10 cm, 20 cm depths, and soil temperature at 5 cm depth was the most crucial influence factor among them. Meanwhile, temperature sensitivity (Q) of R was negatively correlated with soil temperature. Light and temperature exerted strong controls over NEE and GPP. Aboveground biomass over the whole growing season showed non-linear relationships with CO budget, while those during the early and peak growing season showed significant linear relationships with CO budget. This research provides valuable reference for CO exchange in estuarial saline wetland ecosystem. [ABSTRACT FROM AUTHOR]