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| Titel |
High CO2 fluxes from grassland on histic Gleysol along soil carbon and drainage gradients |
| VerfasserIn |
K. Leiber-Sauheitl, R. Fuß, C. Voigt, A. Freibauer |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 3 ; Nr. 11, no. 3 (2014-02-07), S.749-761 |
| Datensatznummer |
250117194
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| Publikation (Nr.) |
 copernicus.org/bg-11-749-2014.pdf |
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| Zusammenfassung |
Drained organic soils are anthropogenic emission hotspots of greenhouse gases
(GHGs). Most studies have focused on deep peat soils and on peats with high
organic carbon content. In contrast, histic Gleysols are characterized by
shallow peat layers, which are left over from peat cutting activities or by
peat mixed with mineral soil. It is unknown whether they emit less GHGs than
deep Histosols when drained. We present the annual carbon and GHG balance of
grasslands for six sites on nutrient-poor histic Gleysols with a shallow
(30 cm) histic horizon or mixed with mineral soil in Northern Germany (soil
organic carbon concentration (Corg) from 9 to 52%).
The net GHG balance, corrected for carbon export by harvest, was around 4 t
CO2–C–eq ha−1 yr−1 on soils with peat layer and little
drainage (mean annual water table < 20 cm below surface). The net
GHG balance reached 7–9 t CO2–C–eq ha−1 yr−1 on soils
with sand mixed into the peat layer and water tables between 14 cm and
39 cm below surface. GHG emissions from drained histic Gleysols (i) were as
high as those from deep Histosols, (ii) increase linearly from shallow to
deeper drainage, (iii) but are not affected by Corg content of
the histic horizon. Ecosystem respiration (Reco) was linearly
correlated with water table level even if it was below the histic horizon.
The Reco/GPP ratio was 1.5 at all sites, so that we ruled out a
major influence of the inter-site variability in vegetation composition on
annual net ecosystem exchange (NEE).
The IPCC definition of organic soils includes shallow histic topsoil, unlike
most national and international definitions of Histosols. Our study confirms
that this broader definition is appropriate considering anthropogenic GHG
emissions from drained organic soils. Countries currently apply soil
maps in national GHG inventories which are likely not to include histic
Gleysols. The land area with GHG emission hotspots due to drainage is likely
to be much higher than anticipated.
Deeply drained histic Gleysols are GHG hotspots that have so far been
neglected or underestimated. Peat mixing with sand does not mitigate GHG
emissions. Our study implies that rewetting organic soils, including histic
Gleysols, has a much higher relevance for GHG mitigation strategies than
currently recognized. |
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