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| Titel |
Moderate effects of reforestation with Norway spruce (Picea abies) on carbon storage and turnover in a Swiss sub-alpine pasture |
| VerfasserIn |
David Hiltbrunner, F. Hagedorn, P. A. Niklaus, S. Zimmermann, M. W. I. Schmidt |
| 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 |
250063368
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| Zusammenfassung |
| In alpine regions the forested area is strongly increasing through woody plant encroachment
on abandoned pastures or by man-made afforestations. These natural or artificial
reforestations, in fact, have several implications on the nutrient cycling between plants and
soils and thus, are likely to affect carbon turnover. Although afforestations are to be
accounted as a sink according to the Kyoto protocol, there are still uncertainties about their
effects on the soil carbon storage.
In the present study, we assessed soils under pasture, an adjacent chronosequence of
spruce afforestations (25-45 years) and a mature spruce forest (older than 120 years) on a
homogenous slope in a Swiss sub-alpine ecosystem. While the soil bulk densities
were not affected by the land use change, carbon concentrations in the mineral soil
decreased 25-45 years after tree establishment. However, no differences between
pasture and the mature forest were apparent, indicating that the C-loss after land use
conversion was only transient. Up to 2.5kg m-2 C was additionally stored in the
organic layer of the oldest stands, resulting in a net C gain in the old forest soils.
C:N-ratios of the soil organic matter (SOM) considerably increased with stand age
in the uppermost soil layer, displaying the distinct chemical composition of the
plant input. In accordance, a shift of the δ13C natural abundance of the SOM in
the uppermost mineral layer towards a less negative signal was observed with tree
development.
The abundance of soil microorganisms, as identified by their phospholipid fatty acids
(PLFA), was only moderately affected by vegetation type in the mineral soils. In
contrast, a strong alteration of the microbial community composition with a decreasing
proportion of fungi from the organic layers to the uppermost mineral layer was
observable.
Our results show that afforestation with spruce trees on an extensively used sub-alpine
pasture only led to a transient loss of C in the mineral soils. In contrast, the accumulation of
additional C in the organic layer resulted in higher C-stocks in the old forest as compared to
the pasture. Therefore, afforestation with coniferous trees is likely to increase the total
amount of C stored, particularly if also the plant biomass is taken into account. |
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