Respiratory responses of higher plants to atmospheric CO2 enrichment

Although the respiratory response of native and agricultural plants to atmospheric CO 2 enrichment has been reported over the past 75 years, only recently have these effects emerged as prominent measures of plant and ecosystem response to the earth's changing climate. In this review we discuss this rapidly expanding field of study and propose that both increasing and decreasing rates of leaf and whole‐plant respiration are likely to occur in response to rising CO 2 concentrations. While the stimulatory effects of CO 2 on respiration are consistent with our knowledge of leaf carbohydrate status and plant metabolism, we wish to emphasize the rather surprising short‐term inhibition of leaf respiration by elevated CO 2 and the reported effects of long‐term CO 2 exposure on growth and maintenance respiration. As is being found in many studies, it is easier to document the respiratory response of higher plants to elevated CO 2 than it is to assign a mechanistic basis for the observed effects. Despite this gap in our understanding of how respiration is affected by CO 2 enrichment, data are sufficient to suggest that changes in leaf and whole‐plant respiration may be important considerations in the carbon dynamics of terrestrial ecosystems as global CO 2 continues to rise. Suggestions for future research that would enable these and other effects of CO 2 on respiration to be unravelled are presented.