RESUMO
Although coastal wetlands play an important role in governing the atmospheric concentrations of CO2, CH4, and N2O, thus control the global warming, research of the greenhouse gas emissions conducted in the coastal wetlands were not well-documented because of the difficulty in fieldwork in these harsh environments, and the complicated controlling factors affecting the greenhouse gas emissions. The temporal and spatial variations of CO2, CH4, and N2O were investigated simultaneously in the coastal saline wetland in North Jiangsu during the period from April, 2014 to March, 2014, using the closed static dark chamber method. And the results showed that seasonal variations of CO2, CH4, and N2O were higher in summer, and lower CO2 and N2O fluxes were observed in winter, while for CH4 in spring, it presented the sink in the coastal wetland. The annual average CO2 emission derived from the Spartina alterniflora flat (SAF) was the highest, with the value of (766.3±496.9) mg·(m2·h)-1, and for CH4 and N2O, the highest values were found in Phragmites australis flat (PAF), with the values of (0.420±0.900) mg·(m2·h)-1 and (17.4±5.0) µg·(m2·h)-1, respectively. The bare mud flat (BF) presented the sink of CH4, and the source of CO2 and N2O, with the lowest emission rates across all the tidal flats. The global warming potential (GWP) from the coastal wetlands in north Jiangsu was observed higher in SAF[68841.280 kg·(hm2·a)-1], which was 1.41 and 3.02 times higher compared with those of PAF and SGF, the GWP of BF was the lowest, with the value of 5002.100 kg·(hm2·a)-1. Furthermore, significant correlations were found between CO2 fluxes and temperature, including air temperature (AT), soil temperature (ST), and temperature inside the chamber (CT), however, for CH4 and N2O, the correlations were not so obvious. Above all, the temporal variations of CO2, CH4, and N2O were mainly controlled by the temperature and characteristics of vegetation, the spatial variations of CO2, CH4, and N2O were determined by the characteristics of vegetation. Furthermore, we may safely draw the conclusion that the invasive S. alterniflora increased the global warming potential dominantly through increasing the CO2 emission rates, compared with the native plant.
