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| Titel |
Alpine grassland soils contain large proportion of labile carbon but indicate long turnover times |
| VerfasserIn |
K. Budge, J. Leifeld, Erika Hiltbrunner, J. Fuhrer |
| 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. 7 ; Nr. 8, no. 7 (2011-07-19), S.1911-1923 |
| Datensatznummer |
250006051
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| Publikation (Nr.) |
 copernicus.org/bg-8-1911-2011.pdf |
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| Zusammenfassung |
| Alpine soils are expected to contain large amounts of labile carbon (C)
which may become a further source of atmospheric carbon dioxide (CO2)
as a result of global warming. However, there is little data available on
these soils, and understanding of the influence of environmental factors on
soil organic matter (SOM) turnover is limited. We extracted 30 cm deep cores
from five grassland sites along a small elevation gradient from 2285 to 2653 m a.s.l. in the central Swiss Alps. Our aim was to
determine the quantity, allocation, degree of stabilization and mean
residence time (MRT) of SOM in relation to site factors such as soil pH,
vegetation, and SOM composition. Soil fractions obtained by size and density
fractionation revealed a high proportion of labile C in SOM, mostly in the
uppermost soil layers. Labile C in the top 20 cm across the gradient ranged
from 39.6–57.6 % in comparison to 7.2–29.6 % reported in previous
studies for lower elevation soils (810–1960 m a.s.l.). At the highest
elevation, MRTs measured by means of radiocarbon dating and turnover
modelling, increased between fractions of growing stability from 90 years in
free POM (fPOM) to 534 years in the mineral associated fraction (mOM).
Depending on elevation and pH, plant community data suggested considerable
variation in the quantity and quality of organic matter input, and these
patterns could be reflected in the dynamics of soil C. 13C NMR data
confirmed a relationship of SOM composition to MRT. While low temperature in
alpine environments is likely to be a major cause for the slow turnover rate
observed, other factors such as residue quality and soil pH, as well as the
combination of all factors, play an important role in causing small scale
variability of SOM turnover. Failing to incorporate this interplay of
controlling factors into models may impair the performance of models to
project SOM responses to environmental change. |
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