Response of CH 4 emissions to moss removal and N addition in boreal peatland of northeast China
Boreal peatlands are an important natural source of atmospheric methane (CH 4). Recently, boreal peatlands have been experiencing increased nitrogen (N) availability and decreased moss production. However, little is known about the interactive effect of moss and N availability on CH 4 emissions in boreal peatlands. In this study, the effects of moss removal and N addition (6 g N m −2 yr −1) on CH 4 emissions were examined during the growing seasons of 2011, 2012 and 2013 in a boreal peatland in the Great Hinggan Mountain of northeast China. Notably, the response of CH 4 emissions to moss removal and N addition varied with experimental duration. Moss removal and N addition did not affect CH 4 emissions in 2011 and 2012, but respectively reduced CH 4 emissions by 50% and 66% in 2013. However, moss removal and N addition did not produce an interactive effect on CH 4 emissions. Consequently, moss removal plus N addition had no effect on CH 4 emissions in 2011 and 2012, but decreased CH 4 emissions by 68% in 2013. These results suggest that the effects of moss removal and N enrichment on CH 4 emissions are time-dependent in boreal peatlands, and also imply that increased N availability and decreased moss growth would independently inhibit CH 4 emissions in the boreal peatlands of northeast China.