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A CO2 Concentration Gradient Facility for Testing CO2 Enrichment and Soil Effects on Grassland Ecosystem Function
Published on: November 21, 2015
Elevated ozone and nitrogen deposition affect nitrogen pools of subalpine grassland
Seraina Bassin1, David Käch1, Alain Valsangiacomo1
1Agroscope, Institute of Sustainability Sciences ISS, Reckenholzstrasse 191, CH-8046 Zurich, Switzerland.
Abstract:
In a free-air fumigation experiment with subalpine grassland, we studied long-term effects of elevated ozone (O3) and nitrogen (N) deposition on ecosystem N pools and on the fate of anthropogenic N. At three times during the seventh year of exposure, N pools and recovery of a stable isotope tracer ((15)N) were determined in above- and belowground plant parts, and in the soil. Plants were much better competitors for (15)N than soil microorganisms. Plant N pools increased by 30-40% after N addition, while soil pools remained unaffected, suggesting that most of the extra N was taken up and stored in plant biomass, thus preventing the ecosystem from acquiring characteristics of eutrophication. Elevated O3 caused an increase of N in microbial biomass and in stabilized soil N, probably resulting from increased litter input and lower litter quality. Different from individual effects, the interaction between the pollutants remained partly unexplained.
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