 |
| Titel |
Eddy-covariance methane flux measurements over a European beech forest |
| VerfasserIn |
Lydia Gentsch, Lukas Siebicke, Alexander Knohl |
| Konferenz |
EGU General Assembly 2015
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250102139
|
| Publikation (Nr.) |
 EGU/EGU2015-1960.pdf |
|
|
|
|
|
| Zusammenfassung |
| The role of forests in global methane (CH4) turnover is currently not well constrained,
partially because of the lack of spatially integrative forest-scale measurements of CH4 fluxes.
Soil chamber measurements imply that temperate forests generally act as CH4 sinks.
Upscaling of chamber observations to the forest scale is however problematic, if the
upscaling is not constrained by concurrent ‘top-down’ measurements, such as of the
eddy-covariance type, which provide sufficient integration of spatial variations and of further
potential CH4 flux components within forest ecosystems. Ongoing development of laser
absorption-based optical instruments, resulting in enhanced measurement stability,
precision and sampling speed, has recently improved the prospects for meaningful
eddy-covariance measurements at sites with presumably low CH4 fluxes, hence prone to
reach the flux detection limit. At present, we are launching eddy-covariance CH4
measurements at a long-running ICOS flux tower site (Hainich National Park, Germany),
located in a semi natural, unmanaged, beech dominated forest. Eddy-covariance
measurements will be conducted with a laser spectrometer for parallel CH4, H2Ov and CO2
measurements (FGGA, Los Gatos Research, USA). Independent observations of the
CO2 flux by the FGGA and a standard Infrared Gas Analyser (LI-7200, LI-COR,
USA) will allow to evaluate data quality of measured CH4 fluxes. Here, we want
to present first results with a focus on uncertainties of the calculated CH4 fluxes
with regard to instrument precision, data processing and site conditions. In future,
we plan to compare eddy-covariance flux estimates to side-by-side turbulent flux
observations from a novel eddy accumulation system. Furthermore, soil CH4 fluxes will
be measured with four automated chambers situated within the tower footprint.
Based on a previous soil chamber study at the same site, we expect the Hainich
forest site to act as a CH4 sink. However, we hypothesize that our measurements
might also reveal short CH4 emission periods when soils become water-saturated.
Nonetheless, CH4 emissions by plants could also result in a close to neutral net CH4 flux. |
|
|
|
|
|
|