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| Titel |
Effect of drought on the carbon dynamics of grassland ecosystems at different altitudes |
| VerfasserIn |
Alexander Heim, O. Joos, A. K. Gilgen, B. Gouskov, R. T. W. Siegwolf, F. Hagedorn, M. W. I. Schmidt, N. Buchmann |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250024512
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| Zusammenfassung |
| Climate change will probably result in an increasing frequency of hot and dry summers in
Central Europe within the next decades. This can have major impacts on ecosystems, because
both temperature and moisture control essential ecosystem processes such as photosynthetic
carbon fixation and mineralisation of organic residues. In this field study, conducted at three
grassland sites between 400 and 2000 m above sea level in Switzerland, we simulated an
artificial drought during early summer, and measured biomass production, soil
respiration and dissolved organic carbon leaching during up to three vegetation
periods.
Mean aboveground production at the alpine site (2000 m) was reduced by drought by about
one third in 2006 and 2007. At the lowland site (400 m), drought did not significantly
affect aboveground biomass production in 2005 and 2006, but reduced it for some
harvests in 2007. At the intermediate altitude, which was in general the wettest of the
three sites, no effect of drought on biomass production was observed over three
years. Belowground biomass production was generally not significantly affected by
drought.
Soil respiration was reduced by about 40% during the drought period. The CO2 flux
originating from root respiration and SOM decomposition was less affected by drought than
the CO2 flux from decomposition of fresh litter. As soon as the simulated drought period was
terminated, soil respiration rates exceeded those in the control, but did not fully
compensate the drought-induced reduction of CO2 efflux within the same vegetation
period.
We provide a synthesis of the results by combining the results from biomass production and
soil efflux with preliminary data from laboratory incubations of biomass grown during the
drought period.
Thus, our results indicate that increasing frequency of droughts might lead to pronounced
changes in the carbon dynamics of grasslands in the short-term. However, uncertainty about
the acclimation of both plant and soil microbial species to such new climatic conditions
precludes long-term predictions based on our data. |
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