Soil-tree-atmosphere CH4 flux dynamics of boreal birch and spruce trees during spring leaf-out

Abstract Aims Studies on tree CH 4 exchange in boreal forests regarding seasonality and role of canopies are rare. We aimed to quantify the contribution trees forest budget during spring leaf-out reveal microbes exchange. Methods Methane fluxes downy birch Norway spruce ( Betula pubescens Picea abies ) growing fen upland sites were measured together with soil flux, environmental variables microbial abundances involved cycle. Tree studied from three stem heights shoots. Results The emitted higher emissions detected shoot spruce. birches at high (mean 45 µg m ?2 h ?1 ), decreasing height. Their dynamics followed temperature, suggesting originated methanogenic activity, manifested mcrA gene copy numbers, peat soil. Methanogens below quantification limit tissues. Upscaled accounted for 22% total fen. Conclusions variation flux between habitats is high, high-emitting increase as proceeds. lack detection methanogens or methanotrophs aboveground plant tissues suggests that these did not have a significant observed tree-derived fluxes. stem-emitted presumably produced microbially