title: Measurements of biosphere-atmosphere exchange of CH₄ in terrestrial ecosystems.
abstract: This chapter focuses on methods for measuring CH(4) exchange between the biosphere and the atmosphere. In the context of the global importance of the biosphere as a source and a sink of atmospheric CH(4,) special emphasis is given to details of gas flux measurements. Due to their widespread use and suitability for targeted process studies, chamber techniques as a means for measuring CH(4) fluxes are highlighted. Besides detailed recommendations for measurements of fluxes with chambers, potential problems of the chamber technique are also discussed, such as changes in environmental conditions due to chamber installations. Further, a short overview is provided of how different pathways of CH(4) exchange, specifically plant-mediated transport, ebullition or diffusion, can be separated and quantified under field conditions. Finally, a short summary of micrometeorological CH(4) measuring techniques such as the eddy covariance method is provided. This technique relies on fast-response sonic anemometers and CH(4) analyzers (~10Hz) to make direct measurements of the vertical CH(4) flux at a point above the vegetation surface.
authors.affiliation: Institute for Meteorology and Climate Research, Atmospheric Environmental Research (IMK-IFU), Karlsruhe Institute of Technology (KIT), Garmisch-Partenkirchen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Butterbach-Bahl
authors.forename: Ralf
authors.initials: R
authors.lastname: Kiese
authors.forename: Chunyan
authors.initials: C
authors.lastname: Liu
mesh_terms: D001272:Atmosphere / Q000032:analysis*; D017753:Ecosystem; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D055904:Meteorology / Q000295:instrumentation; D008697:Methane / Q000032:analysis*; D010944:Plants / Q000737:chemistry
chemical_list: D008697:Methane