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Anders Lindroth

Professor

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A fertile peatland forest does not constitute a major greenhouse gas sink

Author

  • A. Meyer
  • L. Tarvainen
  • A. Nousratpour
  • R. G. Bjork
  • M. Ernfors
  • A. Grelle
  • A. Kasimir Klemedtsson
  • Anders Lindroth
  • M. Rantfors
  • T. Rutting
  • G. Wallin
  • P. Weslien
  • L. Klemedtsson
Show all

Summary, in English

Afforestation has been proposed as a strategy to mitigate the often high greenhouse gas (GHG) emissions from agricultural soils with high organic matter content. However, the carbon dioxide (CO2) and nitrous oxide (N2O) fluxes after afforestation can be considerable, depending predominantly on site drainage and nutrient availability. Studies on the full GHG budget of afforested organic soils are scarce and hampered by the uncertainties associated with methodology. In this study we determined the GHG budget of a spruce-dominated forest on a drained organic soil with an agricultural history. Two different approaches for determining the net ecosystem CO2 exchange (NEE) were applied, for the year 2008, one direct (eddy covariance) and the other indirect (analyzing the different components of the GHG budget), so that uncertainties in each method could be evaluated. The annual tree production in 2008 was 8.3 +/- 3.9 tC ha(-1) yr(-1) due to the high levels of soil nutrients, the favorable climatic conditions and the fact that the forest was probably in its phase of maximum C assimilation or shortly past it. The N2O fluxes were determined by the closed-chamber technique and amounted to 0.9 +/- 0.8 t C-eq ha(-1) yr(-1). According to the direct measurements from the eddy covariance technique, the site acts as a minor GHG sink of -1.2 +/- 0.8 t C-eq ha(-1) yr(-1). This contrasts with the NEE estimate derived from the indirect approach which suggests that the site is a net GHG emitter of 0.6 +/- 4.5 t C-eq ha(-1) yr(-1). Irrespective of the approach applied, the soil CO2 effluxes counter large amounts of the C sequestration by trees. Due to accumulated uncertainties involved in the indirect approach, the direct approach is considered the more reliable tool. As the rate of C sequestration will likely decrease with forest age, the site will probably become a GHG source once again as the trees do not compensate for the soil C and N losses. Also forests in younger age stages have been shown to have lower C assimilation rates; thus, the overall GHG sink potential of this afforested nutrient-rich organic soil is probably limited to the short period of maximum C assimilation.

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • eSSENCE: The e-Science Collaboration
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2013

Language

English

Pages

7739-7758

Publication/Series

Biogeosciences

Volume

10

Issue

11

Document type

Journal article

Publisher

Copernicus GmbH

Topic

  • Physical Geography

Status

Published

ISBN/ISSN/Other

  • ISSN: 1726-4189