Biogeosciences www.biogeosciences.net 1726-4170 1726-4189 6 11 2009 10.5194/bg-6-2525-2009 http://www.biogeosciences.net/6/2525/2009/ http://www.biogeosciences.net/6/2525/2009/bg-6-2525-2009.html http://www.biogeosciences.net/6/2525/2009/bg-6-2525-2009.pdf 2525 2539 2009-11-09 Response of temperate grasslands at different altitudes to simulated summer drought differed but scaled with annual precipitation A. K. Gilgen anna.gilgen@ips.unibe.ch N. Buchmann Institute of Plant Sciences, ETH Zurich, Zurich, Switzerland present address: Institute of Plant Sciences, University of Bern, Bern, Switzerland 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 (<i>R</i>²=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. 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