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| Titel |
Alaskan soil carbon stocks: spatial variability and dependence on environmental factors |
| VerfasserIn |
U. Mishra, W. J. Riley |
| 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. 9 ; Nr. 9, no. 9 (2012-09-20), S.3637-3645 |
| Datensatznummer |
250007292
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| Publikation (Nr.) |
 copernicus.org/bg-9-3637-2012.pdf |
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| Zusammenfassung |
| The direction and magnitude of soil organic carbon (SOC) changes in response
to climate change depend on the spatial and vertical distributions of SOC. We
estimated spatially resolved SOC stocks from surface to C horizon,
distinguishing active-layer and permafrost-layer stocks, based on geospatial
analysis of 472 soil profiles and spatially referenced environmental
variables for Alaska. Total Alaska state-wide SOC stock was estimated to be
77 Pg, with 61% in the active-layer, 27% in permafrost, and
12% in non-permafrost soils. Prediction accuracy was highest for the
active-layer as demonstrated by highest ratio of performance to deviation
(1.5). Large spatial variability was predicted, with whole-profile,
active-layer, and permafrost-layer stocks ranging from
1–296 kg C m−2, 2–166 kg m−2, and 0–232 kg m−2,
respectively. Temperature and soil wetness were found to be primary
controllers of whole-profile, active-layer, and permafrost-layer SOC stocks.
Secondary controllers, in order of importance, were found to be land cover
type, topographic attributes, and bedrock geology. The observed importance of
soil wetness rather than precipitation on SOC stocks implies that the poor
representation of high-latitude soil wetness in Earth system models may lead
to large uncertainty in predicted SOC stocks under future climate change
scenarios. Under strict caveats described in the text and assuming
temperature changes from the A1B Intergovernmental Panel on Climate Change
emissions scenario, our geospatial model indicates that the equilibrium
average 2100 Alaska active-layer depth could deepen by 11 cm, resulting in a
thawing of 13 Pg C currently in permafrost. The equilibrium SOC loss
associated with this warming would be highest under continuous permafrost
(31%), followed by discontinuous (28%), isolated (24.3%), and
sporadic (23.6%) permafrost areas. Our high-resolution mapping of soil
carbon stock reveals the potential vulnerability of high-latitude soil carbon
and can be used as a basis for future studies of anthropogenic and climatic
perturbations. |
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