Reduced N cycling in response to elevated CO2, warming, and drought in a Danish heathland: Synthesizing results of the CLIMAITE project after two years of treatments
| Autor: | Inger Kappel Schmidt, Louise C. Andresen, Mette Sustmann Carter, Martin Holmstrup, Claus Beier, Jane Kongstad, Soren Christensen, Kristine Maraldo, Kristian Rost Albert, Merete Bang Selsted, Kim Pilegaard, Sven Jonasson, Klaus Steenberg Larsen, Anders Priemé, Karen Stevnbak, Per Ambus, M.F. Arndal, Leon van der Linden, Teis Nørgaard Mikkelsen, Anders Michelsen, Helge Ro-Poulsen, Andreas Ibrom |
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| Rok vydání: | 2010 |
| Předmět: |
Calluna
Biogeochemical cycle Denitrification 010504 meteorology & atmospheric sciences 01 natural sciences Mineralization (biology) Animal science Botany Environmental Chemistry Ecosystem Nitrogen cycle 0105 earth and related environmental sciences General Environmental Science 2. Zero hunger Global and Planetary Change Ecology biology 04 agricultural and veterinary sciences 15. Life on land biology.organism_classification 13. Climate action Deschampsia flexuosa 040103 agronomy & agriculture 0401 agriculture forestry and fisheries Environmental science Cycling |
| Zdroj: | Global Change Biology. 17:1884-1899 |
| ISSN: | 1354-1013 |
| Popis: | Field-scale experiments simulating realistic future climate scenarios are important tools for investigating the effects of current and future climate changes on ecosystem functioning and biogeochemical cycling. We exposed a semi-natural Danish heathland ecosystem to elevated atmospheric carbon dioxide (CO2), warming, and extended summer drought in all combinations. Here, we report on the short-term responses of the nitrogen (N) cycle after two years of treatments. Elevated CO2 significantly affected above-ground stoichiometry by increasing the carbon to nitrogen (C/N) ratios in the leaves of both co-dominant species (Calluna vulgaris and Deschampsia flexuosa), as well as the C/N ratios of Calluna flowers and by reducing the N concentration of Deschampsia litter. Below-ground, elevated CO2 had only minor effects, whereas warming increased N turnover, as indicated by increased rates of microbial NH4+-N consumption, gross mineralization, potential nitrification, denitrification and N2O emissions. Drought reduced below-ground gross N mineralization and decreased fauna N mass and N mineralization. Leaching was unaffected by treatments but was significantly higher across all treatments in the second year than in the much drier first year indicating that ecosystem N loss is highly sensitive to changes and variability in amount and timing of precipitation. Interactions between treatments were common and although some synergistic effects were observed, antagonism dominated the interactive responses in treatment combinations, i.e. responses were smaller in combinations than in single treatments. Nonetheless, increased C/N ratios of photosynthetic tissue, decreased litter N production, and decreased fauna N mineralization prevailed in the full treatment combination indicating reduced N turnover in the simulated future climate scenario, which could act to reduce the potential growth response of plants to elevated atmospheric CO2 concentration. In conclusion, effects observed in single-factor studies should be evaluated with caution. Multi-factor climate experiments are needed for improving realistic estimation of the combined ecosystem responses to future climate changes. |
| Databáze: | OpenAIRE |
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