Effects of long-term elevated CO2 on foliage characteristics of Quercus ilex L. and Juniperus communis L.

To study the effects of long-term elevated CO2 on Quercus ilex and Juniperus communis, leaves from plants growing close to a natural CO2 spring and from plants at a control site were collected and analyzed. Starch concentrations in leaves were found to be higher for plants growing under high CO2. Nitrogen concentrations were lower, but only in Juniperus communis. No differences in stomatal densities were found. The results indicate that in a CO2 -elevated environment, growth of both species will be different: Quercus ilex will be able to take advantage of the higher CO2 levels in spring, whereas in both species limited sink availability in the middle of the growing season will result in increased starch concentrations.