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| Titel |
Fluxes of N2O and CH4 from forest and grassland lysimeter soils in response to simulated climate change |
| VerfasserIn |
Daniel Weymann, Nicolas Brueggemann, Thomas Puetz, Harry Vereecken |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250109331
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| Publikation (Nr.) |
 EGU/EGU2015-9234.pdf |
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| Zusammenfassung |
| Central Europe is expected to be exposed to altered temperature and hydrological conditions,
which will affect the vulnerability of nitrogen and carbon cycling in soils and thus production
and fluxes of climate relevant trace gases. However, knowledge of the response of greenhouse
gas fluxes to climate change is limited so far, but will be an important basis for future climate
projections.
Here we present preliminary results of an ongoing lysimeter field study which aims to
assess the impact of simulated climate change on N2O and CH4 fluxes from a forest and a
fertilized grassland soil. The lysimeters are part of the Germany-wide research
infrastructure TERENO, which investigates feedbacks of climate change to the
pedosphere on a long-term scale. Lysimeters (A = 1m2) were established in 2010 at high
elevated sites (HE, 500 and 600 m.a.s.l.) and subsequently transferred along an
altitudinal gradient to a low elevated site (LE, 100 m.a.s.l.) within the Eifel / Lower
Rhine Valley Observatory in Western Germany, thereby resulting in a temperature
increase of 2.3 K whereas precipitation decreased by 160 mm during the present study
period. Systematic monitoring of soil-atmosphere exchange of N2O and CH4 based
on weekly manual closed chamber measurements at HE and LE sites has started
in August 2013. Furthermore, we routinely determine dissolved N2O and CH4
concentrations in the seepage water using a headspace equilibration technique and
record water discharge in order to quantify leaching losses of both greenhouse
gases.
Cumulative N2O fluxes clearly responded to simulated climate change conditions and
increased by 250 % and 600 % for the forest and the grassland soil, respectively. This
difference between the HE and LE sites was mainly caused by an exceptionally heavy
precipitation event in July 2014 which turned the LE site sustainably to a consistently higher
emission level. Nonetheless, emissions remained rather small and ranged between 20 and 40
μg m-2 h-1. In terms of CH4, the forest soil exhibits a consistent uptake. Climate change
conditions almost doubled the CH4 sink strength from -0.14 to -0.27 g C m-2 year-1. In
contrast, the grassland soil was a net source of CH4 which appeared to be mainly related to
emission peaks responding to organic fertilization and periods with high soil moisture.
However, the net source strength was so far not significantly affected by simulated climate
change.
In conclusion, our preliminary results provide evidence that climate change will
considerably affect N2O emissions from both soils as well as CH4 uptake by the forest soil.
However, comparatively small fluxes of both trace gases suggest that N2O and CH4 fluxes of
the investigated soils will be of minor importance for the net greenhouse gas balance of
our sites. Our data further highlight the need for long-term flux measurements, in
particular to account for the impact of short-term events and interannual variability. |
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