caa a22 4500 467885788 CHVBK 20180406152734.0 cr unu---uuuuu 170328e20061201xx s 000 0 eng 10.1007/s10021-006-0163-5 doi (NATIONALLICENCE)springer-10.1007/s10021-006-0163-5 Elevated CO2 and O3 Alter Soil Nitrogen Transformations beneath Trembling Aspen, Paper Birch, and Sugar Maple [Elektronische Daten] [William Holmes, Donald Zak, Kurt Pregitzer, John King] Nitrogen cycling in northern temperate forest ecosystems could change under increasing atmospheric CO2 and tropospheric O3 as a result of quantitative and qualitative changes in plant litter production. At the Aspen Free Air CO2-O3 Enrichment (FACE) experiment, we previously found that greater substrate inputs to soil under elevated CO2 did not alter gross N transformation rates in the first 3 years of the experiment. We hypothesized that greater litter production under elevated CO2 would eventually cause greater gross N transformation rates and that CO2 effects would be nullified by elevated O3. Following our original study, we continued measurement of gross N transformation rates for an additional four years. From 1999 to 2003, gross N mineralization doubled, N immobilization increased 4-fold, but changes in microbial biomass N and soil total N were not detected. We observed year-to-year variation in N transformation rates, which peaked during a period of foliar insect damage. Elevated CO2 caused equivalent increases in gross rates of N mineralization (+34%) and NH 4 + immobilization (+36%). These results indicate greater rates of N turnover under elevated CO2, but do not indicate a negative feedback between elevated CO2 and soil N availability. Elevated O3 decreased gross N mineralization (−16%) and had no effect on NH 4 + immobilization, indicating reduced N availability under elevated O3. The effects of CO2 and O3 on N mineralization rates were mainly related to changes in litter production, whereas effects on N immobilization were likely influenced by changes in litter chemistry and production. Our findings also indicate that concomitant increases in atmospheric CO2 and O3 could lead to a negative feedback on N availability. Springer Science+Business Media, Inc., 2007 Acer saccharum nationallicence Betula papyrifera nationallicence Carbon dioxide nationallicence FACE nationallicence Gross N immobilization nationallicence Gross N mineralization nationallicence Microbial biomass nationallicence Nitrogen cycling nationallicence Ozone nationallicence Populus tremuloides nationallicence Holmes William School of Natural Resources & Environment, University of Michigan, 48109-1115, Ann Arbor, Michigan, USA aut Zak Donald School of Natural Resources & Environment, University of Michigan, 48109-1115, Ann Arbor, Michigan, USA aut Pregitzer Kurt School of Forest Resources & Environmental Science, Michigan Technological University, 49931, Houghton, Michigan, USA aut King John Department of Forestry and Environmental Science, North Carolina State University, 27695, Raleigh, North Carolina, USA aut Ecosystems Springer-Verlag; www.springer-ny.com 9/8(2006-12-01), 1354-1363 1432-9840 9:8<1354 2006 9 10021 https://doi.org/10.1007/s10021-006-0163-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10021-006-0163-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Holmes William School of Natural Resources & Environment, University of Michigan, 48109-1115, Ann Arbor, Michigan, USA aut NATIONALLICENCE 700 1- Zak Donald School of Natural Resources & Environment, University of Michigan, 48109-1115, Ann Arbor, Michigan, USA aut NATIONALLICENCE 700 1- Pregitzer Kurt School of Forest Resources & Environmental Science, Michigan Technological University, 49931, Houghton, Michigan, USA aut NATIONALLICENCE 700 1- King John Department of Forestry and Environmental Science, North Carolina State University, 27695, Raleigh, North Carolina, USA aut NATIONALLICENCE 773 0- Ecosystems Springer-Verlag; www.springer-ny.com 9/8(2006-12-01), 1354-1363 1432-9840 9:8<1354 2006 9 10021 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer