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| Titel |
How accurately can soil organic carbon stocks and stock changes be quantified by soil inventories? |
| VerfasserIn |
M. Schrumpf, E. D. Schulze, K. Kaiser, J. Schumacher |
| 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 (2011-05-18), S.1193-1212 |
| Datensatznummer |
250005816
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| Publikation (Nr.) |
 copernicus.org/bg-8-1193-2011.pdf |
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| Zusammenfassung |
Precise determination of changes in organic carbon (OC) stocks is
prerequisite to understand the role of soils in the global cycling of carbon
and to verify changes in stocks due to management. A large dataset was
collected to form base to repeated soil inventories at 12 CarboEurope sites
under different climate and land-use, and with different soil types.
Concentration of OC, bulk density (BD), and fine earth fraction were
determined to 60 cm depth at 100 sampling points per site. We investigated
(1) time needed to detect changes in soil OC, assuming future re-sampling of
100 cores; (2) the contribution of different sources of uncertainties to OC
stocks; (3) the effect of OC stock calculation on mass rather than volume
base for change detection; and (4) the potential use of pedotransfer
functions (PTF) for estimating BD in repeated inventories.
The period of time needed for soil OC stocks to change strongly enough to be
detectable depends on the spatial variability of soil properties, the depth
increment considered, and the rate of change. Cropland sites, having small
spatial variability, had lower minimum detectable differences (MDD) with 100
sampling points (105 ± 28 gC m−2 for the upper 10 cm of the soil)
than grassland and forest sites (206 ± 64 and 246 ± 64 gC m−2
for 0–10 cm, respectively). Expected general trends in soil OC
indicate that changes could be detectable after 2–15 yr with 100 samples
if changes occurred in the upper 10 cm of stone-poor soils. Error
propagation analyses showed that in undisturbed soils with low stone
contents, OC concentrations contributed most to OC stock variability while
BD and fine earth fraction were more important in upper soil layers of
croplands and in stone rich soils. Though the calculation of OC stocks based
on equivalent soil masses slightly decreases the chance to detect changes
with time at most sites except for the croplands, it is still recommended to
account for changing bulk densities with time. Application of PTF for the
estimation of bulk densities caused considerable underestimation of total
variances of OC stocks if the error associated with the PTF was not
accounted for, which rarely is done in soil inventories. Direct measurement
of all relevant parameters approximately every 10 yr is recommended for
repeated soil OC inventories. |
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