 |
| Titel |
Methane and nitrous oxide exchange over a managed hay meadow |
| VerfasserIn |
L. Hörtnagl, G. Wohlfahrt |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 24 ; Nr. 11, no. 24 (2014-12-17), S.7219-7236 |
| Datensatznummer |
250117745
|
| Publikation (Nr.) |
 copernicus.org/bg-11-7219-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| The methane (CH4) and nitrous oxide (N2O) exchange of a temperate
mountain grassland near Neustift, Austria, was measured during 2010–2012
over a time period of 22 months using the eddy covariance method. Exchange
rates of both compounds at the site were low, with 97% of all
half-hourly CH4 and N2O fluxes ranging between ±200 and
±50 ng m−2 s−1, respectively. The meadow acted as a sink
for both compounds during certain time periods, but was a clear source of
CH4 and N2O on an annual timescale. Therefore, both gases
contributed to an increase of the global warming potential (GWP),
effectively reducing the sink strength in terms of CO2 equivalents of
the investigated grassland site. In 2011, our best guess estimate showed a
net greenhouse gas (GHG) sink of −32 g CO2 equ. m−2 yr−1 for the meadow,
whereby 55% of the CO2 sink strength of −71 g CO2 m−2 yr−1
was offset by CH4 (N2O) emissions of 7 (32) g CO2 equ. m−2 yr−1. When all data were pooled, the ancillary
parameters explained 27 (42)% of observed CH4 (N2O) flux
variability, and up to 62 (76)% on shorter timescales in-between
management dates. In the case of N2O fluxes, we found the highest emissions at
intermediate soil water contents and at soil temperatures close to 0 or
above 14 °C.
In comparison to CO2, H2O and energy fluxes, the interpretation of
CH4 and N2O exchange was challenging due to footprint
heterogeneity regarding their sources and sinks, uncertainties regarding
post-processing and quality control. Our results emphasize that CH4 and
N2O fluxes over supposedly well-aerated and moderately fertilized soils
cannot be neglected when evaluating the GHG impact of temperate managed
grasslands. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|