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Smith Lecture: Ecosystem Response to Rising Atmospheric Carbon Dioxide and Ozone: Synthesis of a Long-Term Field Experiment

Sep
28
2012

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• Speaker: Don Zak, University of Michigan
• Host Department: Earth and Environmental Sciences
• Date: 09/28/2012
• Time: 04:00PM - 05:00PM
  
  
• Location: 1528 C.C. Little Building
  
  
• Description:

  The accumulation of anthropogenic CO₂ in the Earth’s atmosphere, and hence the rate of climate warming, is sensitive to stimulation of plant growth by higher concentrations of atmospheric CO₂.  In this presentation, I will synthesize data from a long-term, field experiment in which three developing northern forest communities have been exposed to factorial combinations of elevated CO₂and O₃.  Enhanced growth (~26% increase) under elevated CO₂was sustained by greater root exploration of soil for growth-limiting N, as well as more rapid rates of litter decomposition and microbial N release during decay.  Despite initial declines in forest productivity under elevated O₃, compensatory growth of O₃-tolerant individuals resulted in equivalent growth under ambient and elevated O₃.  After a decade, forest growth has remained enhanced under elevated CO₂and has recovered under elevated O₃by mechanisms that remain un-calibrated or not considered in coupled climate-biogeochemical models simulating interactions between the global C cycle and climate warming.