PARENT SESSION
Symposium #26: Gasping for CO₂: Ecological Effects of Past Variations in Atmospheric CO2.

Organized by: JW Williams and S Cowling
Thursday, August 8. 9:00 AM to 11:30 AM. Turquoise Ballroom, TCC.

Physiological and evolutionary responses of plants to low CO₂ of the late Pleistocene.

Ward, Joy^*,1, Ehleringer, James¹, ¹ University of Utah, Salt Lake City, UT

ABSTRACT- Recently, plant physiological ecologists have been interested in the effects of low atmospheric CO₂ concentrations on the physiology, growth, and evolution of plants. This interest is in response to ice core data indicating that CO₂ concentrations were as low as 180 ppm during glacial periods of the late Pleistocene (relative to a modern value of 370 ppm). This talk will review the recent advancements in understanding how plants may have survived and evolved in response to these low CO₂ concentrations that were highly stressful on C₃ plants, due to limitations in carbon availability. The talk will highlight both experimental work conducted with modern plants developed under past conditions and the responses of ancient vegetation (e.g. wood samples from the La Brea tar pits) that can be measured with stable isotope analysis. The overall aim of this talk will be an attempt to understand how C₃ plants persisted during periods of low CO₂ during the late Pleistocene when carbon would have been a major limiting resource for plants.

KEY WORDS: low CO₂, carbon limitations, Pleistocene, plant stress