Methane exchange of a boreal forest
Elin Sundqvist1, Anders Lindroth1
1 Department of physical geography and ecosystems analysis, Lund University
P34 in Poster presentations
Factors controlling the exchange of methane in a forest ecosystem need to be further studied. Methane is oxidized in forest soils that are well drained but it is not clear how large this uptake is and which factors that control the uptake. Anaerobic environments like wetlands were thought to be the one important source of methane in forest ecosystems, but in 2006, Keppler et al, reported that plants could emit methane also under aerobic conditions. At Norunda forest site in central Sweden, a new project started in 2007 aiming at studying the methane exchange of a mixed pine and spruce forest in detail. The whole ecosystem CH4 exchange will be calculated based on measurements of CH4 gradients above the canopy and the turbulent diffusivity. A gas chromatograph was used to measure the CH4 concentration at three levels above the canopy: 32, 58 and 100 m. The turbulent diffusivity is calculated based on measurements from an eddy covariance system. To see how the variation of CH4 concentration over time depends on the origin of the air, the position of the air masses five days before entering the measuring area will be tracked. The whole ecosystem CH4 exchange will also be compared with data of soil CH4 fluxes. Fluxes at soil level have been measured manually and can, due to a strong correlation with soil respiration, be calculated for the periods when data is missing. Results will be presented in October.
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