ATMOSPHERIC CO2 AND THE RATIO OF INTERCELLULAR TO AMBIENT CO2 CONCENTRATIONS IN PLANTS

Much attention is focused today on predicting how plants will respond to anticipated changes in atmospheric composition and climate, and in particular to increases in CO2 concentration. Here we review the long- term global fluctuations in atmospheric CO2 concentration as a framewo rk for understanding how current trends in atmospheric CO2 concentrati on fit into a selective, evolutionary context. We then focus on an int egrated approach for understanding how gas exchange metabolism respond s to current environmental conditions, how it previously responded to glacial-interglacial conditions, and how it may respond to future chan ges in atmospheric CO2 concentration.