Growing season methane emissions from a permafrost peatland of northeast China: Observations using open-path eddy covariance method

Abstract The mid-high latitude permafrost peatlands in the Northern Hemisphere is a major natural source of methane (CH 4 ) to the atmosphere. Ecosystem scale CH 4 emissions from a typical permafrost peatland in the Great Hing'an Mountains were observed during the growing season of 2014 and 2015 using the open-path eddy covariance method. Relevant environmental factors such as temperature and precipitation were also collected. There was a clear diurnal variation in methane emissions in the second half of each growing season, with significantly higher emission rates in the wet sector of study area. The daily CH 4 exchange ranged from 1.8 mg CH 4 m −2  d −1 to 40.2 mg CH 4 m −2  d −1 in 2014 and ranged from −3.9 to 15.0 mg CH 4 m −2  d −1 in 2015. There were no peaks of CH 4 fluxes during the spring thawing period. However, large peaks of CH 4 emission were found in the second half of both growing seasons. The CH 4 emission after Jul 25th accounted for 77.9% of total growing season emission in 2014 and 85.9% in 2015. The total CH 4 emission during the growing season of 2014 and 2015 was approximately 1.52 g CH 4  m −2 and 0.71 g CH 4  m −2 , respectively. CH 4 fluxes during the growing seasons were significantly correlated with thawing depth ( R 2  = 0.71, P R 2  = 0.75, P 4 emissions in permafrost peatlands. Our multiyear observations indicate that the time-lagged volume of precipitation during the growing season is a key factor in interpreting locally inter-annual variations in CH 4 emissions. Our results suggested that the low temperature in the deep soil layers effectively restricts methane production and emission rates; these conditions may create significant positive feedback under global climate change.