High emissions of greenhouse gases from grasslands on peat and other organic soils

authored by

Bärbel Tiemeyer, Elisa Albiac Borraz, Jürgen Augustin, Michel Bechtold, Sascha Beetz, Colja Beyer, Matthias Drösler, Martin Ebli, Tim Eickenscheidt, Sabine Fiedler, Christoph Förster, Annette Freibauer, Michael Giebels, Stephan Glatzel, Jan Heinichen, Mathias Hoffmann, Heinrich Höper, Gerald Jurasinski, Katharina Leiber-Sauheitl, Mandy Peichl-Brak, Niko Roßkopf, Michael Sommer, Jutta Zeitz

Abstract

Drainage has turned peatlands from a carbon sink into one of the world's largest greenhouse gas (GHG) sources from cultivated soils. We analyzed a unique data set (12 peatlands, 48 sites and 122 annual budgets) of mainly unpublished GHG emissions from grasslands on bog and fen peat as well as other soils rich in soil organic carbon (SOC) in Germany. Emissions and environmental variables were measured with identical methods. Site-averaged GHG budgets were surprisingly variable (29.2 ± 17.4 t CO₂-eq. ha⁻¹ yr⁻¹) and partially higher than all published data and the IPCC default emission factors for GHG inventories. Generally, CO₂ (27.7 ± 17.3 t CO₂ ha⁻¹ yr⁻¹) dominated the GHG budget. Nitrous oxide (2.3 ± 2.4 kg N₂O-N ha⁻¹ yr⁻¹) and methane emissions (30.8 ± 69.8 kg CH₄-C ha⁻¹ yr⁻¹) were lower than expected except for CH₄ emissions from nutrient-poor acidic sites. At single peatlands, CO₂ emissions clearly increased with deeper mean water table depth (WTD), but there was no general dependency of CO₂ on WTD for the complete data set. Thus, regionalization of CO₂ emissions by WTD only will remain uncertain. WTD dynamics explained some of the differences between peatlands as sites which became very dry during summer showed lower emissions. We introduced the aerated nitrogen stock (N_air) as a variable combining soil nitrogen stocks with WTD. CO₂ increased with N_air across peatlands. Soils with comparatively low SOC concentrations showed as high CO₂ emissions as true peat soils because N_air was similar. N₂O emissions were controlled by the WTD dynamics and the nitrogen content of the topsoil. CH₄ emissions can be well described by WTD and ponding duration during summer. Our results can help both to improve GHG emission reporting and to prioritize and plan emission reduction measures for peat and similar soils at different scales.

External Organisation(s)

Johann Heinrich von Thünen Institute, Federal Research Institute for Rural Areas, Forestry and Fisheries
Leibniz Centre for Agricultural Landscape Research (ZALF)
University of Rostock
State Authority for Mining, Energy and Geology (LBEG)
University of Applied Sciences Weihenstephan-Triesdorf
Johannes Gutenberg University Mainz
Technical University of Munich (TUM)
University of Hohenheim
Meo Carbon Solutions GmbH
University of Vienna
Humboldt-Universität zu Berlin (HU Berlin)
Landesamt für Bergbau, Geologie und Rohstoffe Brandenburg (LBGR)

Type

Article

Journal

Global change biology

Volume

22

Pages

4134-4149

No. of pages

16

ISSN

1354-1013

Publication date

12.2016

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Global and Planetary Change, Environmental Chemistry, Ecology, General Environmental Science

Sustainable Development Goals

SDG 13 - Climate Action

Electronic version(s)

https://doi.org/10.1111/gcb.13303 (Access: Closed)