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| Titel |
Estimating soil organic carbon stocks of Swiss forest soils by robust external-drift kriging |
| VerfasserIn |
M. Nussbaum, A. Papritz, A. Baltensweiler, L. Walthert |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1991-959X
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| Digitales Dokument |
URL |
| Erschienen |
In: Geoscientific Model Development ; 7, no. 3 ; Nr. 7, no. 3 (2014-06-25), S.1197-1210 |
| Datensatznummer |
250115637
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| Publikation (Nr.) |
 copernicus.org/gmd-7-1197-2014.pdf |
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| Zusammenfassung |
Accurate estimates of soil organic carbon (SOC) stocks are required to quantify carbon sources and
sinks caused by land use change at national scale. This study presents a novel robust kriging
method to precisely estimate regional and national mean SOC stocks, along with truthful standard
errors. We used this new approach to estimate mean forest SOC stock for Switzerland and for its
five main ecoregions.
Using data of 1033 forest soil profiles, we modelled stocks of two compartments (0–30,
0–100 cm depth) of mineral soils. Log-normal regression models that accounted for
correlation between SOC stocks and environmental covariates and residual (spatial)
auto-correlation were fitted by a newly developed robust restricted maximum likelihood method,
which is insensitive to outliers in the data.
Precipitation, near-infrared reflectance, topographic and aggregated information of a soil and
a geotechnical map were retained in the models. Both models showed weak but significant residual
autocorrelation. The predictive power of the fitted models, evaluated by comparing predictions
with independent data of 175 soil profiles, was moderate (robust R2 = 0.34 for SOC stock in
0–30 cm and R2 = 0.40 in 0–100 cm). Prediction standard errors (SE),
validated by comparing point prediction intervals with data, proved to be conservative.
Using the fitted models, we mapped forest SOC stock by robust external-drift point kriging at high
resolution across Switzerland. Predicted mean stocks in 0–30 and 0–100 cm
depth were equal to 7.99 kg m−2 (SE 0.15 kg m−2) and
12.58 kg m−2 (SE 0.24 kg m−2), respectively. Hence, topsoils store about
64% of SOC stocks down to 100 cm depth. Previous studies underestimated SOC stocks
of topsoil slightly and those of subsoils strongly. The comparison further revealed that our
estimates have substantially smaller SE than previous estimates. |
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