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| Titel |
Constraint of soil moisture on CO2 efflux from tundra lichen, moss, and tussock in Council, Alaska, using a hierarchical Bayesian model |
| VerfasserIn |
Y. Kim, K. Nishina, N. Chae, S. J. Park, Y. J. Yoon, B. Y. Lee |
| 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 ; 11, no. 19 ; Nr. 11, no. 19 (2014-10-13), S.5567-5579 |
| Datensatznummer |
250117635
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| Publikation (Nr.) |
 copernicus.org/bg-11-5567-2014.pdf |
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| Zusammenfassung |
| The tundra ecosystem is quite vulnerable to drastic climate change in the
Arctic, and the quantification of carbon dynamics is of significant
importance regarding thawing permafrost, changes to the snow-covered period
and snow and shrub community extent, and the decline of sea ice in the
Arctic. Here, CO2 efflux measurements using a manual chamber system
within a 40 m × 40 m (5 m interval; 81 total points) plot were
conducted within dominant tundra vegetation on the Seward Peninsula of
Alaska, during the growing seasons of 2011 and 2012, for the assessment of
driving parameters of CO2 efflux. We applied a hierarchical Bayesian
(HB) model – a function of soil temperature, soil moisture, vegetation type,
and thaw depth – to quantify the effects of environmental factors on
CO2 efflux and to estimate growing season CO2 emissions. Our
results showed that average CO2 efflux in 2011 was 1.4 times higher than
in 2012, resulting from the distinct difference in soil moisture between the
2 years. Tussock-dominated CO2 efflux is 1.4 to 2.3 times higher than
those measured in lichen and moss communities, revealing tussock as a
significant CO2 source in the Arctic, with a wide area distribution on
the circumpolar scale. CO2 efflux followed soil temperature nearly
exponentially from both the observed data and the posterior medians of the HB
model. This reveals that soil temperature regulates the seasonal variation of
CO2 efflux and that soil moisture contributes to the interannual
variation of CO2 efflux for the two growing seasons in question. Obvious
changes in soil moisture during the growing seasons of 2011 and 2012 resulted
in an explicit difference between CO2 effluxes – 742 and
539 g CO2 m−2 period−1 for 2011 and 2012, respectively,
suggesting the 2012 CO2 emission rate was reduced to 27% (95%
credible interval: 17–36%) of the 2011 emission, due to higher soil moisture from severe rain.
The estimated growing season CO2 emission rate ranged from
0.86 Mg CO2 in 2012 to 1.20 Mg CO2 in 2011 within a
40 m × 40 m plot, corresponding to 86 and 80% of annual
CO2 emission rates within the western Alaska tundra ecosystem, estimated
from the temperature dependence of CO2 efflux. Therefore, this HB model
can be readily applied to observed CO2 efflux, as it demands only four
environmental factors and can also be effective for quantitatively assessing
the driving parameters of CO2 efflux. |
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