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| Titel |
Response of temperate grasslands at different altitudes to simulated summer drought differed but scaled with annual precipitation |
| VerfasserIn |
A. K. Gilgen, N. Buchmann |
| 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 ; 6, no. 11 ; Nr. 6, no. 11 (2009-11-09), S.2525-2539 |
| Datensatznummer |
250004089
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| Publikation (Nr.) |
 copernicus.org/bg-6-2525-2009.pdf |
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| Zusammenfassung |
| Water is an important resource for plant life. Since climate scenarios for
Switzerland predict an average reduction of 20% in summer precipitation
until 2070, understanding ecosystem responses to water shortage, e.g. in
terms of plant productivity, is of major concern. Thus, we tested the
effects of simulated summer drought on three managed grasslands along an
altitudinal gradient in Switzerland from 2005 to 2007, representing typical
management intensities at the respective altitude. We assessed the effects
of experimental drought on above- and below-ground productivity, stand
structure (LAI and vegetation height) and resource use (carbon and water).
Responses of community above-ground productivity to reduced precipitation
input differed among the three sites but scaled positively with total annual
precipitation at the sites (R2=0.85). Annual community above-ground
biomass productivity was significantly reduced by summer drought at the
alpine site receiving the least amount of annual precipitation, while no
significant decrease (rather an increase) was observed at the pre-alpine
site receiving highest precipitation amounts in all three years. At the
lowland site (intermediate precipitation sums), biomass productivity
significantly decreased in response to drought only in the third year, after
showing increased abundance of a drought tolerant weed species in the second
year. No significant change in below-ground biomass productivity was
observed at any of the sites in response to simulated summer drought.
However, vegetation carbon isotope ratios increased under drought
conditions, indicating an increase in water use efficiency. We conclude that
there is no general drought response of Swiss grasslands, but that sites
with lower annual precipitation seem to be more vulnerable to summer drought
than sites with higher annual precipitation, and thus site-specific
adaptation of management strategies will be needed, especially in regions
with low annual precipitation. |
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