Document: JAC-3-99-172

Physiological ecology and global change: Adding mechanism to the madness of predicting the future.

JACKSON, R.B.* ¹ and R.K.MONSON ²

Duke University, Durham, NC 27706-8001 ¹
University of Colorado, Boulder, CO 80302-7077 ²

Abstract:
The physiological ecology of plants and animals provides a mechanistic framework for predicting the consequences of global change and understanding feedbacks with the biosphere. Whether the driver of global change is rising atmospheric CO₂, increasing temperature, or altered nitrogen deposition, organism physiology is altered in fundamental and predictable ways. Nonetheless, such physiological changes must also be integrated with changes at scales above and below the organism. We discuss the role of physiological ecology in predicting the consequences of global change, including the effects of elevated temperature and carbon dioxide, interpreting satellite and eddy flux data, and understanding feedbacks with atmospheric composition. Elevated CO₂ affects photosynthesis and stomatal conductance differently for plant functional types (e.g., angiosperms vs. gymnosperms), leading to different predictions geographically and latitudinally. Similarly, the distribution and abundance of C₃ and C₄ plants can be predicted fairly well from physiological responses to such environmental variables as temperature, light, and water, with projected shifts for the coming century. Physiological ecology also plays an important role in understanding the controls over the exchange of reactive chemical species with the atmosphere. Global isoprene emissions cause approximately a 20% increase in the tropospheric lifetime of methane; such modeling results use algorithms developed primarily through ecophysiological research and help us develop prognostic scenarios of how climate warming will influence forest isoprene emissions and perturb the lifetime of atmospheric methane.

Keywords: global change

This abstract is being presented at: 3:15 PM in session:
Symposium # 16: Plant Physiological Ecology: Linking the Organism to Scales Above and Below.