“…Constructed wetlands (CWs), a natural alternative to technological methods of wastewater treatment, have been widely used Christensen, 2001;van der Gon and Neue, 1996); (2) A wide range of labile carbon compounds, including organic acids, sugars, and amino acids, are released into the root zones through plant root systems, stimulating methanogens and their activities (Bais et al, 2006;Bertin et al, 2003;Ström et al, 2005); (3) Aquatic plants can mediate the transport of CH 4 emission from wetlands through aerenchyma, increasing the net CH 4 emission in the environment (Morin et al, 2014;Rice et al, 2010;Rusch and Rennenberg, 1998); (4) Some plants themselves can emit CH 4 under aerobic (Bruhn et al, 2012;Keppler et al, 2008Keppler et al, , 2009Wishkerman et al, 2011) or anaerobic conditions (Rice et al, 2010;Wang et al, 2011). The presence of plants may reduce (Maltais-Landry et al, 2009) or increase CH 4 emissions in the CW units.…”