Elevated CO2 studies: past, present and future

Increasing concentrations of atmospheric CO2 are predicted to impact both c urrent and future ecosystems. Elevated CO2 is also predicted to affect biol ogical processes at many levels of organization. In this overview, we summa rize the responses of plants to elevated CO2 including primary physiologica l and molecular responses, growth and reproductive responses, effects on pl ant-plant competition and interactions with other organisms, evolutionary r esponses, and effects at the ecosystem level. The objectives of this paper are to: (a) overview studies in this issue that were presented at a 1997 me eting entitled "Critical Assessment of the Response of Forest Ecosystems to Elevated Atmospheric Carbon Dioxide," which was sponsored by the Global Ch ange and Terrestrial Ecosystems (GCTE) group of the International Geosphere Biosphere Program (IGBP), (b) review areas of recent progress in CO2 resea rch, (c) generalize patterns arising from past research, and (d) list criti cal areas of research for the future.