Temperature, soil moisture, and microbial controls on CO2 and CH4 emissions from a permafrost peatland

Abstract Peatlands are significant carbon dioxide (CO 2 ) sinks and methane (CH 4 ) sources. In this study, we investigated changes in CO 2 and CH 4 emissions from topsoil (0–20 cm) to subsoil (20–40 cm) in a permafrost peatland, and the related soil microbial abundance in response to increasing temperature and soil water content by using an incubation experiment. Our results indicated that CO 2 and CH 4 emissions from the permafrost peatland are highly sensitive to temperature and soil water content. CO 2 emissions from topsoil and subsoil at 15°C were 3.36 and 2.74 times larger, respectively, compared to those at 5°C under the field moisture condition, and were 1.70 times larger under the waterlogged treatment in both topsoil and subsoil. CH 4 emissions from 0–20 to 20–40 cm soils at 15°C were 34 and 83 times larger, respectively, than those at 5°C under the original state and 17 and 32 times larger under the waterlogged treatment. These results indicated that CH 4 emissions are more sensitive than CO 2 emissions, and waterlogged conditions could decrease temperature sensitivity of CO 2 and CH 4 emissions. Microbial analyses showed that the cumulative emissions amount of CO 2 positively correlated with bacterial, fungal, and methanotroph abundances. Positive relationships were observed between CH 4 emissions and abundances of bacteria, fungi, and archaea. These findings suggested that changes in temperature and water content alter CO 2 and CH 4 emissions from permafrost peatlands through controlling abundances of soil bacteria, fungi, archaea, and methanotrophs. These variables bear importance in accurately estimating C emissions from permafrost peatlands.