Response of temperate grasslands at different altitudes to simulated summer drought differed but scaled with annual precipitation
Gilgen, A. K.
- Working Paper
Water is an important resource for plant live. 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 drought on above- and below-ground productivity, stand structure (LAI and vegetation height) and resource use (carbon and water). Drought responses of community above-ground productivity differed among the three sites but scaled positively with total annual precipitation at the sites (<i>R</i><sup>2</sup>=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, community 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 measures will be needed especially in regions with low annual precipitation Show more
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Journal / seriesBiogeosciences Discussions
Organisational unit03648 - Buchmann, Nina
NotesReceived 17 April 2009, Accepted 11 May 2009, Published 25 May 2009.
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