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| Titel |
How do land use intensity, experimentally increased temperature and water level affect methane and nitrous oxide emissions from a drained fen peatland? |
| VerfasserIn |
Jan Heinichen, Tim Eickenscheidt, Matthias Drösler |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250097594
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| Publikation (Nr.) |
 EGU/EGU2014-13193.pdf |
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| Zusammenfassung |
| Rewetting and extensification of peatlands is widely discussed and practiced to reduce losses
of CO2 and N2O from drained peat soils. But rewetting is known to carry the risk of
increased CH4 emissions. Up to now it is not completely clear how the predicted temperature
increase in the face of climate change will alter the N2O and CH4 exchange of grasslands on
drained peatland soils in the temperate zone. Therefore we investigated the effects of land use
intensity, increased groundwater level, increased temperature and the combination
of warming and increased groundwater level on CH4 and N2O exchange of two
grassland sites (intensive and extensive grassland) in a drained fen peatland in southern
Germany.
We set up a factorial design on both land use types, on each three treatments, warming,
increased water table level and the combination of warming and increased water table level as
well as a control site were established. Temperature was manipulated with open-top
chambers (OTCs) and water level manipulation was performed using a pumping
system and sheet pile walls. The intensive grassland was cut three times in the year,
the extensive grassland once in autumn 2011. Cattle slurry and mineral fertilizer
(CAN) were deployed on the intensive grassland. Fluxes of CH4 and N2O were
measured biweekly from December 2010 to January 2012 using opaque static closed
chambers.
The annual mean groundwater level (GWL) of the sites without water level manipulation
was -41.5 cm b. g. and -30 cm b. g. at the water level manipulated sites on the intensive
grassland. On the extensive grassland the GWL of the sites without water level manipulation
was -32 cm b. g. and -21.5 cm b. g. at the water level manipulated sites. Air temperature in
0.2 m was increased in 2011 by 0.7 °C at the treatments with OTCs on the intensive
grassland and by 1.0 °C at the treatments with OTCs on the extensive grassland
respectively.
The annual cumulative CH4 exchange ranged from 8.1 ± 3.8 kg C ha-1 yr-1 to 36.3 ±
8.6 kg C ha-1 yr-1on the extensive grassland and from -0.1 ± 0.3 kg C ha-1 yr-1 to
15.0 ± 1.9 kg C ha-1 yr-1 on the intensive grassland. The CH4 emissions of the
treatments with increased water level on the intensive grassland were significantly higher
compared to the control and warming sites. No significant differences could be observed
between CH4 emissions of the treatments on the extensive grassland. However, we
found a general significant relationship between CH4 fluxes, groundwater level and
temperature.
All sites on the intensive grassland show higher annual emissions of N2O compared to the
sites on the extensive grassland. The annual cumulative N2O exchange ranged from 3.1 ± 0.5
kg N ha-1 yr-1 to 6.1 ± 0.4 kg N ha-1 yr-1on the intensive grassland and from 0.7 ± 0.1 kg
N ha-1 yr-1 to 1.3 ± 0.2 kg N ha-1 yr-1 on the extensive grassland. Significant
treatment effects could not be observed for N2O exchange on both land use types. |
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