Diurnal variations of carbon dioxide,methane,and nitrous oxide fluxes from invasive Spartina alterniflora dominated coastal wetland in northern Jiangsu Province

• Published in: Acta oceanologica Sinica 2017-04, Vol.36 (4), p.105-113
• Main Authors: Xu, Xinwanghao, Fu, Guanghe, Zou, Xinqing, Ge, Chendong, Zhao, Yifei
• Format: Article
• Language: English
• Subjects: Air temperature; Aquatic plants; Biodiversity; Carbon dioxide; Climate change; Climatology; Daily; Diffusion rate; Diurnal variations; Earth and Environmental Science; Earth Sciences; Ecological function; Ecology; Emissions; Engineering Fluid Dynamics; Environmental Chemistry; Fluxes; Gases; Global warming; Greenhouse effect; Greenhouse gases; Growing season; Introduced species; Invasive species; Logging; Marine; Marine & Freshwater Sciences; Methane; Nitrous oxide; Oceanography; Sampling; Scaling; Seasons; Soil temperature; Spartina alterniflora; Summer; Tidal flats; Wetlands; 二氧化碳; 互花米草; 外来入侵植物; 日变化; 氧化亚氮; 江苏省; 滨海湿地; 甲烷通量
• ISSN: 0253-505X; 1869-1099
• DOI: 10.1007/s13131-017-1015-1

The invasions of the alien species such as Spartina alterniflora along the northern Jiangsu coastlines have posed a threat to biodiversity and the ecosystem function.Yet,limited attention has been given to their potential influence on greenhouse gas（GHG） emissions,including the diurnal variations of GHG fluxes that are fundamental in estimating the carbon and nitrogen budget.In this study,we examined the diurnal variation in fluxes of carbon dioxide（CO_2）,methane（CH_4）,and nitrous oxide（N2O） from a S.alterniflora intertidal flat in June,October,and December of 2013 and April of 2014 representing the summer,autumn,winter,and spring seasons,respectively.We found that the average CH_4 fluxes on the diurnal scale were positive during the growing season while negative otherwise.The tidal flat of S.alterniflora acted as a source of CH_4 in summer（June） and a combination of source and sink in other seasons.We observed higher diurnal variations in the CO_2 and N_2O fluxes during the growing season（1 536.5 mg CO_2 m~（–2） h~（–1） and 25.6 μg N_2O m~（–2） h~（–1）） compared with those measured in the non-growing season（379.1 mg CO_2 m~（–2） h~（–1） and 16.5 μg N_2O m~（–2） h~（–1））.The mean fluxes of CH_4 were higher at night than that in the daytime during all the seasons but October.The diurnal variation in the fluxes of CO_2 in June and N_2O in December fluctuated more than that in October and April.However,two peak curves in October and April were observed for the diurnal changes in CO_2 and N_2O fluxes（prominent peaks were found in the morning of October and in the afternoon of April,respectively）.The highest diurnal variation in the N_2O fluxes took place at 15：00（86.4 μg N_2O m~（–2） h~（–1）） in June with an unimodal distribution.Water logging in October increased the emission of CO_2（especially at nighttime）,yet decreased N_2O and CH_4 emissions to a different degree on the daily scale because of the restrained diffusion rates of the gases.The seasonal and diurnal variations of CH_4 and CO_2 fluxes did not correlate to the air and soil temperatures,whereas the seasonal and diurnal variation of the fluxes of N_2O in June exhibited a significant correlation with air temperature.When N_2O and CH_4 fluxes were converted to CO_2-e equivalents,the emissions of N_2O had a remarkable potential to impact the global warming.The mean daily flux（MF） and total daily flux（TDF） were higher in the growing season,nevertheless,the MF and TDF of CO_2 were higher in October and those of C