Pulse labelling of deep soil layers in forest with 13CH4: testing a new method for tracing methane in the upper horizons, understorey vegetation and tree stems using laserbased spectrometry

<p>Methane is one the main greenhouse gases and upland forests are one of its main biological sinks. However, vegetation could reduce this sink by allowing a direct path for the methane produced in deep soils to escape into the atmosphere. By tracing emissions with ¹³CH₄, we show for the first time that methane emitted by trees in upland forest could have a deep soil origin even though the soil is an overall methane sink. However, we found that the trees and understorey vegetation at our site had only a small impact on the methane budget.</p>