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| Titel |
Temporal and spatial variations of soil CO2, CH4 and N2O fluxes at three differently managed grasslands |
| VerfasserIn |
D. Imer, L. Merbold, W. Eugster, N. Buchmann |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 9 ; Nr. 10, no. 9 (2013-09-10), S.5931-5945 |
| Datensatznummer |
250085327
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| Publikation (Nr.) |
 copernicus.org/bg-10-5931-2013.pdf |
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| Zusammenfassung |
| A profound understanding of temporal and spatial variabilities of soil carbon
dioxide (CO2), methane (CH4) and nitrous oxide (N2O) fluxes
between terrestrial ecosystems and the atmosphere is needed to reliably
quantify these fluxes and to develop future mitigation strategies. For
managed grassland ecosystems, temporal and spatial variabilities of these
three soil greenhouse gas (GHG) fluxes occur due to changes in environmental
drivers as well as fertilizer applications, harvests and grazing. To assess
how such changes affect soil GHG fluxes at Swiss grassland sites, we studied
three sites along an altitudinal gradient that corresponds to a management
gradient: from 400 m a.s.l. (intensively managed) to 1000 m a.s.l.
(moderately intensive managed) to 2000 m a.s.l. (extensively managed). The
alpine grassland was included to study both effects of extensive management
on CH4 and N2O fluxes and the different climate regime occurring at
this altitude. Temporal and spatial variabilities of soil GHG fluxes and
environmental drivers on various timescales were determined along transects
of 16 static soil chambers at each site. All three grasslands were N2O
sources, with mean annual soil fluxes ranging from 0.15 to
1.28 nmol m−2 s−1. Contrastingly, all sites were weak CH4
sinks, with soil uptake rates ranging from −0.56 to
−0.15 nmol m−2 s−1. Mean annual soil and plant respiration
losses of CO2, measured with opaque chambers, ranged from 5.2 to
6.5 μmol m−2 s−1. While the environmental drivers and
their respective explanatory power for soil N2O emissions differed
considerably among the three grasslands (adjusted r2 ranging from 0.19 to
0.42), CH4 and CO2 soil fluxes were much better constrained
(adjusted r2 ranging from 0.46 to 0.80) by soil water content and air
temperature, respectively. Throughout the year, spatial heterogeneity was
particularly high for soil N2O and CH4 fluxes. We found permanent
hot spots for soil N2O emissions as well as locations of permanently
lower soil CH4 uptake rates at the extensively managed alpine site.
Including hot spots was essential to obtain a representative mean soil flux
for the respective ecosystem. At the intensively managed grassland,
management effects clearly dominated over effects of environmental drivers on
soil N2O fluxes. For CO2 and CH4, the importance of management
effects did depend on the status of the vegetation (LAI). |
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