Brown,J.R., Blankinship,J.C., Niboyet,A., van Groenigen,K.J., Dijkstra,P., Le Roux,X., Leadley,P.W. and Hungate,B.A.(2012): Effects of multiple global change treatments on soil N2O fluxes. Biogeochemistry, 109, 85-100.

『土壌N2Oフラックスに対する複合的な世界的変化の処理の影響』


Abstract
 Global environmental changes are expected to alter ecosystem carbon and nitrogen cycling, but the interactive effects of multiple simultaneous environmental changes are poorly understood. Effects of these changes on the production of nitrous oxide (N2O), an important greenhouse gas, could accelerate climate change. We assessed the responses of soil N2O fluxes to elevated CO2, heat, altered precipitation, and enhanced nitrogen deposition, as well as their interactions, in an annual grassland at the Jasper Ridge Global Change Experiment (CA, USA). Measurements were conducted after 6, 7 and 8 years of treatments. Elevated precipitation increased N2O efflux, especially in combination with added nitrogen and heat. Path analysis supported the idea that increased denitrification due to increased soil water content and higher labile carbon availability best explained increased N2O efflux, with a smaller, indirect contribution from nitrification. In our data and across the literature, single-factor responses tended to overestimate interactive responses, except when global change was combined with disturbance by fire, in which case interactive effects were large. Thus, for chronic global environmental changes, higher order interactions dampened responses of N2O efflux to multiple global environmental changes, but interactions were strongly positive when global change was combined with disturbance. Testing whether these responses are general should be a high priority for future research.

Keywords: Interactions; Global environmental change; Elevated CO2; Warming; Precipitation; Nitrogen deposition; Soil; Grassland; FACE; Nitrification; Denitrification; Meta-analysis』

Introduction
Materials and methods
 Study site and experimental design
 Field N2O fluxes
 Drivers of N2O efflux
 Statistical analyses
  Analysis of variance
  Correlations and path analysis
  Observed versus expected interactive effects: Jasper Ridge Global Change Experiment
  Observed versus expected interactive effects: meta-analysis
Results
 Field N2O efflux
 Drivers of N2O efflux
 Combined effects and interactions - Jasper Ridge Global Change Experiment
 Combined effects and interactions - meta-analysis
Discussion
 Soil N2O emissions and microbial drivers
 Responses to precipitation and interactions with heat and nitrogen
 Responses to N, heat, and CO2
 Interactive responses of soil N2O emissions to global environmental change
Conclusions
Acknowledgments
References


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