 |
| Titel |
Eddy covariance methane flux measurements over a grazed pasture: effect of cows as moving point sources |
| VerfasserIn |
R. Felber, A. Münger, A. Neftel, C. Ammann |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 12 ; Nr. 12, no. 12 (2015-06-29), S.3925-3940 |
| Datensatznummer |
250118004
|
| Publikation (Nr.) |
 copernicus.org/bg-12-3925-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| Methane (CH4) from ruminants contributes one-third of global
agricultural greenhouse gas emissions. Eddy covariance (EC) technique has
been extensively used at various flux sites to investigate carbon dioxide
exchange of ecosystems. Since the development of fast CH4 analyzers, the
instrumentation at many flux sites has been amended for these gases. However,
the application of EC over pastures is challenging due to the spatially and
temporally uneven distribution of CH4 point sources induced by the grazing
animals. We applied EC measurements during one grazing season over a pasture
with 20 dairy cows (mean milk yield: 22.7 kg d−1) managed in a
rotational grazing system. Individual cow positions were recorded by GPS
trackers to attribute fluxes to animal emissions using a footprint model.
Methane fluxes with cows in the footprint were up to 2 orders of magnitude
higher than ecosystem fluxes without cows. Mean cow emissions of
423 ± 24 g CH4 head−1 d−1 (best estimate from this
study) correspond well to animal respiration chamber measurements reported in
the literature. However, a systematic effect of the distance between source
and EC tower on cow emissions was found, which is attributed to the analytical
footprint model used. We show that the EC method allows one to determine CH4
emissions of cows on a pasture if the data evaluation is adjusted for this
purpose and if some cow distribution information is available. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|