 |
| Titel |
Initiation of methane turbulent flux measurements over a grazed grassland in Belgium |
| VerfasserIn |
Pierre Dumortier, Marc Aubinet, Henri Chopin, Alain Debacq, Elisabeth Jérôme, Yves Beckers, Bernard Heinesch |
| Konferenz |
EGU General Assembly 2013
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250073466
|
|
|
|
|
|
| Zusammenfassung |
| Methane fluxes emitted by a grazed meadow were measured continuously during the 2012
grazing season at the Dorinne Terrestrial Observatory (50Ë 18’ 44” N; 4Ë 58’ 07” E; 248 m
asl.) in Belgium. Measurements were made with the eddy covariance technique, using a
fast CH4 analyzer (Picarro G2311-f). Carbon dioxide fluxes (LI-7000) and various
micro-meteorological and soil variables, biomass growth and stocking rate evolution were
also measured at the site. The site is an intensively pastured meadow of 4.2 ha
managed according to the regional usual practices where up to 30 cows are grazing
simultaneously. N2O emissions are currently measured through dynamic closed
chambers (Beekkerk van Ruth et al., Geophysical Research Abstracts. Vol. 15,
EGU2013-3211, 2013) and the carbon budget of the site has already been investigated
(Jerome et al. Geophysical Research Abstracts, Vol. 15, EGU2013-6989, 2013). As
no CH4 measurements were available, CH4 fluxes were estimated on the basis of
dry matter intake by the cows and a conversion factor obtained from a literature
review. We want to improve this estimation by measuring CH4 fluxes, identifying
their main environmental drivers and understanding diurnal and annual exchange
patterns.
Methane emissions were found strongly related with cattle stocking rate with a slope of
7.34±0.78 mol CH4 day-1 LSU-1. Up to now, no methane absorption has been observed,
the meadow behaving as a methane emitter, even in the absence of cows. In the absence of
cows, no significant relation can be established up to now between methane emissions and
environmental parameters. No clear diurnal evolution is observed, neither during grazing
periods nor during cow free periods. During cow presence periods, fluxes are highly
variable, probably due to cow movements in and out the measurement footprint
and cow digestion rhythm. Further developments are ongoing in order to improve
cattle geo-localization through individual home-made GPS devices and infra-red
cameras. The two systems will be compared in terms of cost, efficiency and ease of
use.
Key words: grassland, methane fluxes, eddy covariance, cattle emissions |
|
|
|
|
|
|