Elevated ozone and nitrogen deposition affect nitrogen pools of subalpine grassland.
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.
['Bassin|Seraina|S|', 'Käch|David|D|', 'Valsangiacomo|Alain|A|', 'Mayer|Jochen|J|', 'Oberholzer|Hans-Rudolf|HR|', 'Volk|Matthias|M|', 'Fuhrer|Jürg|J|']
D018533:Biomass D017753:Ecosystem D065948:Grassland D009584:Nitrogen D010126:Ozone D012987:Soil
Ozone Nitrogen Grassland Stable isotopes Soil