Temporal variations in methane emissions from emergent aquatic macrophytes in two boreonemoral lakes

Methane (CH4) emissions via emergent aquatic macrophytes can contribute substantially to the global CH4 balance. We addressed temporal variability in CH4 flux by using the static chamber approach to quantify fluxes from plots dominated by two species considered to differ in flux transport mechanisms (Phragmites australis, Carex rostrata). Temporal variability in daily mean emissions from early June to early October was substantial. The variable that best explained this variation was air temperature. Regular and consistent diel changes were absent and therefore less relevant to include when estimating or modelling CH4 emissions. Methane emissions per m(2) from nearby plots were similar for Phragmites australis and Carex rostrata indicating that CH4 production in the system influenced emissions more than the species identity. This study indicates that previously observed diel patterns and specieseffects on emissions require further evaluation to support improved local and regional CH4 flux assessments.Funding Agencies|European Research Council [VR 2012-48, VR 2011-3575, 725546]; Stiftelsen Oscar och Lili Lamms Minne [EX2014-0010]; Swedish research council: VR and Formas; Swedish Research Council