Global Changes and Implications for Plant Communities.

Convincing arguments are being made that global changes are moving ecosystems towards novel conditions that past experience will provide only limited information upon which to base forecasts of future performance.  In particular, present atmospheric CO₂ concentrations are higher than Earth has experienced for at least the past 650,000 years, and are very likely to move into concentrations not seen for millions of years by the end of this century.  Similarly, climate change is thought to be moving present-day climate space into novel combinations of temperature and precipitation patterns not seen recently in many world regions.  Although environment envelope approaches which rely on present-day knowledge of plant assemblages will continue to be important for predicting the future, identification of critical plant, soil and ecosystem traits will become increasingly important for predicting how plant communities may evolve, migrate and function in response to global change.   I will use examples of our present ecological knowledge of Great Plains grassland plant species and their physiological responses to CO₂, temperature and precipitation to illustrate how plant communities may evolve as global change proceeds.