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| Titel |
Direct comparison of repeated soil inventory and carbon flux budget to detect soil carbon stock changes in grassland |
| VerfasserIn |
C. Ammann, J. Leifeld, A. Neftel, J. Fuhrer |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250069528
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| Zusammenfassung |
| Experimental assessment of soil carbon (C) stock changes over time is typically based on
the application of either one of two methods, namely (i) repeated soil inventory
and (ii) determination of the ecosystem C budget or net biome productivity (NBP)
by continuous measurement of CO2 exchange in combination with quantification
of other C imports and exports. However, there exist hardly any published study
hitherto that directly compared the results of both methods. Here, we applied both
methods in parallel to determine C stock changes of two temperate grassland fields
previously converted from long-term cropland. The grasslands differed in management
intensity with either intensive management (high fertilization, frequent cutting)
or extensive management (no fertilization, less frequent cutting). Soil organic C
stocks (0–45 cm depth) were quantified at the beginning (2001) and the end (2006)
of a 5 year observational period using the equivalent soil mass approach. For the
same period and in both fields, NBP was quantified from net CO2 fluxes monitored
using eddy covariance systems, and measured C import by organic fertilizer and C
export by harvest. Both NBP and repeated soil inventories revealed a consistent and
significant difference between management systems of 170 ± 48 and 253 ± 182 g C
m-2 a-1, respectively. For both fields, the inventory method showed a tendency
towards higher C loss/smaller C gain than NBP. In the extensive field, a significant C
loss was observed by the inventory but not by the NBP approach. Thus both, flux
measurements and repeated soil sampling, seem to be adequate and equally suited for
detecting relative management effects. However, the suitability for tracking absolute
changes in SOC could not be proven for neither of the two methods. Overall, our
findings stress the need for more direct comparisons to evaluate whether the observed
difference in the outcome of the two approaches reflects a general methodological
bias, which would have important implications for regional terrestrial C budgets. |
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