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| Titel |
Exploring the sensitivity of soil carbon dynamics to climate change, fire disturbance and permafrost thaw in a black spruce ecosystem |
| VerfasserIn |
J. A. O'Donnell, J. W. Harden, A. D. McGuire, V. E. Romanovsky |
| 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 ; 8, no. 5 ; Nr. 8, no. 5 (2011-05-27), S.1367-1382 |
| Datensatznummer |
250005827
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| Publikation (Nr.) |
 copernicus.org/bg-8-1367-2011.pdf |
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| Zusammenfassung |
| In the boreal region, soil organic carbon (OC) dynamics are strongly
governed by the interaction between wildfire and permafrost. Using a
combination of field measurements, numerical modeling of soil thermal
dynamics, and mass-balance modeling of OC dynamics, we tested the
sensitivity of soil OC storage to a suite of individual climate factors (air
temperature, soil moisture, and snow depth) and fire severity. We also
conducted sensitivity analyses to explore the combined effects of fire-soil
moisture interactions and snow seasonality on OC storage. OC losses were
calculated as the difference in OC stocks after three fire cycles (~500 yr)
following a prescribed step-change in climate and/or fire.
Across single-factor scenarios, our findings indicate that warmer air
temperatures resulted in the largest relative soil OC losses (~5.3 kg C m−2),
whereas dry soil conditions alone (in the absence of wildfire)
resulted in the smallest carbon losses (~0.1 kg C m−2). Increased
fire severity resulted in carbon loss of ~3.3 kg C m−2, whereas
changes in snow depth resulted in smaller OC losses (2.1–2.2 kg C m−2).
Across multiple climate factors, we observed larger OC losses than for
single-factor scenarios. For instance, high fire severity regime associated
with warmer and drier conditions resulted in OC losses of ~6.1 kg C m−2,
whereas a low fire severity regime associated with warmer and
wetter conditions resulted in OC losses of ~5.6 kg C m−2. A
longer snow-free season associated with future warming resulted in OC losses
of ~5.4 kg C m−2. Soil climate was the dominant control on soil
OC loss, governing the sensitivity of microbial decomposers to fluctuations
in temperature and soil moisture; this control, in turn, is governed by
interannual changes in active layer depth. Transitional responses of the
active layer depth to fire regimes also contributed to OC losses, primarily
by determining the proportion of OC into frozen and unfrozen soil layers. |
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