title: Nitrous oxide and methane emissions from cryptogamic covers.
abstract: Cryptogamic covers, which comprise some of the oldest forms of terrestrial life on Earth (Lenton & Huntingford, ), have recently been found to fix large amounts of nitrogen and carbon dioxide from the atmosphere (Elbert et al., ). Here we show that they are also greenhouse gas sources with large nitrous oxide (N2 O) and small methane (CH4 ) emissions. Whilst N2 O emission rates varied with temperature, humidity, and N deposition, an almost constant ratio with respect to respiratory CO2 emissions was observed for numerous lichens and bryophytes. We employed this ratio together with respiration data to calculate global and regional N2 O emissions. If our laboratory measurements are typical for lichens and bryophytes living on ground and plant surfaces and scaled on a global basis, we estimate a N2 O source strength of 0.32-0.59 Tg year(-1) for the global N2 O emissions from cryptogamic covers. Thus, our emission estimate might account for 4-9% of the global N2 O budget from natural terrestrial sources. In a wide range of arid and forested regions, cryptogamic covers appear to be the dominant source of N2 O. We suggest that greenhouse gas emissions associated with this source might increase in the course of global change due to higher temperatures and enhanced nitrogen deposition.
authors.affiliation: Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany.|Department of Plant Ecology, Justus-Liebig-University, Heinrich-Buff-Ring 26-32, Gießen, 35392, Germany.|Institute of Earth Sciences, University of Heidelberg, Im Neuenheimer Feld 234-236, Heidelberg, 69120, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Lenhart
authors.affiliation: Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany.
authors.forename: Bettina
authors.initials: B
authors.lastname: Weber
authors.affiliation: Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Elbert
authors.affiliation: Senckenberg Biodiversity and Climate Research Centre, Senckenberganlage 25, Frankfurt am Main, 60325, Germany.
authors.forename: Jörg
authors.identifier: http://orcid.org/0000-0002-7861-8789
authors.initials: J
authors.lastname: Steinkamp
authors.affiliation: Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln, 7647, New Zealand.
authors.forename: Tim
authors.initials: T
authors.lastname: Clough
authors.affiliation: Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Crutzen
authors.affiliation: Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Pöschl
authors.affiliation: Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, Mainz, 55128, Germany.|Institute of Earth Sciences, University of Heidelberg, Im Neuenheimer Feld 234-236, Heidelberg, 69120, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Keppler
mesh_terms: D000393:Air Pollutants / Q000032:analysis*; D001315:Australia; D044002:Bryophyta / Q000378:metabolism; D000458:Cyanobacteria / Q000378:metabolism; D004784:Environmental Monitoring; D005060:Europe; D005658:Fungi / Q000378:metabolism; D017752:Greenhouse Effect; D008011:Lichens / Q000378:metabolism; D008697:Methane / Q000032:analysis*; D058086:Microalgae / Q000378:metabolism; D008962:Models, Theoretical; D009520:New Zealand; D009609:Nitrous Oxide / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D009609:Nitrous Oxide; D008697:Methane
keywords: cryptogamic covers; global change; global upscaling; methane; nitrous oxide