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| Titel |
Decadal variability of soil CO2, NO, N2O, and CH4 fluxes at the Höglwald Forest, Germany |
| VerfasserIn |
G. J. Luo, N. Brüggemann, B. Wolf, R. Gasche, R. Grote, K. Butterbach-Bahl |
| 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 ; 9, no. 5 ; Nr. 9, no. 5 (2012-05-21), S.1741-1763 |
| Datensatznummer |
250007027
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| Publikation (Nr.) |
 copernicus.org/bg-9-1741-2012.pdf |
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| Zusammenfassung |
Besides agricultural soils, temperate forest soils have been identified as
significant sources of or sinks for important atmospheric trace gases
(N2O, NO, CH4, and CO2). Although the number of studies for
this ecosystem type increased more than tenfold during the last decade,
studies covering an entire year and spanning more than 1–2 years remained
scarce. This study reports the results of continuous measurements of
soil-atmosphere C- and N-gas exchange with high temporal resolution carried
out since 1994 at the Höglwald Forest spruce site, an experimental field
station in Southern Germany. Annual soil N2O, NO and CO2 emissions
and CH4 uptake (1994–2010) varied in a range of
0.2–3.0 kg N2O-N ha−1yr−1, 6.4–11.4 kg NO-N ha−1yr−1, 7.0–9.2 t
CO2-C ha−1yr−1, and 0.9–3.5 kg CH4-C ha−1yr−1, respectively. The observed high fluxes of N-trace gases are most
likely a consequence of high rates of atmospheric nitrogen deposition
(>20 kg N ha−1yr−1) of NH3 and NOx to our site. For
N2O, cumulative annual emissions were ≥ 0.8 kg N2O-N ha−1yr−1 in years with freeze-thaw events (5 out 14 of years). This shows that
long-term, multi-year measurements are needed to obtain reliable estimates
of N2O fluxes for a given ecosystem. Cumulative values of soil
respiratory CO2 fluxes tended to be highest in years with prolonged
freezing periods, i.e. years with below average annual mean soil
temperatures and high N2O emissions (e.g. the years 1996 and 2006).
Furthermore, based on our unique database on trace gas fluxes we analyzed if
soil temperature, soil moisture measurements can be used to approximate
trace gas fluxes at daily, weekly, monthly, or annual scale. Our analysis
shows that simple-to-measure environmental drivers such as soil temperature
or soil moisture are suitable to approximate fluxes of NO and CO2 at
weekly and monthly resolution reasonably well (accounting for up to 59 %
of the variance). However, for CH4 we so far failed to find meaningful
correlations, and also for N2O the predictive power is rather low. This
is most likely due to the complexity of involved processes and counteracting
effects of soil moisture and temperature, specifically with regard to
N2O production and consumption by denitrification and microbial
community dynamics. At monthly scale, including information on gross primary
production (CO2, NO), and N deposition (N2O), increased
significantly the explanatory power of the obtained empirical regressions
(CO2: r2 =0.8; NO: r2 = 0.67; N2O, all data: r2 = 0.5; N2O, with exclusion of freeze-thaw periods: r2 = 0.65). |
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