Examining Soil Carbon Gas (CO2, CH4) Emissions and the Effect on Functional Microbial Abundances in the Zhangjiang Estuary Mangrove Reserve

Mangrove soil is regarded as an important source of CO2 and CH4 because of its large carbon pools. However, little is known about the magnitudes of CO2 and CH4 emitted from mangrove soils and their relationships with functional microbial abundances. Here, a field experiment was conducted in Zhangjiang Estuary Mangrove from August 2014 to September 2016. Soils dominated by species Kandelia obovata (KO), Avicennia marina (AM), and bare mudflat (Mud) were randomly established, respectively. The results showed that soil of the Zhangjiang Estuary Mangrove wetland is a significant source of CH4 (ranging from -35.36 to 2822.52 mu g m(-2) h(-1)) and CO2 (ranging from -28.45 to 116.26 mg m(-2) h(-1)), with a significant spatial and seasonal variation pattern. The soil CH4 emissions were positively correlated to the mcrA gene abundance and organic matter content. Meanwhile, the 16S rRNA and ANME-pmoA gene abundances were positively correlated to the soil CO2 emissions. When considering only the soil-atmosphere exchange of carbon gas, soil CO2 emission was the major contributor to the global warming potential, accounting for 64.66%-96.11%. The profound variations of soil CH4 and CO2 emissions may imply the important role of dominant mangrove vegetation on soil microbes and carbon gas emissions.