XVI International Botanical Congess

We evaluated mycorrhizal and soil microbial responses to elevated CO2 and eutrophication in a series of growth chamber and field studies in a Mediterranean-type ecosystem. Elevated CO2 resulted in an increase in carbon allocated belowground. In response to elevated CO2, there was an increase in carbon allocation to the fungal food web and to mycorrhizae in response to growing nutrient deficiencies in the plant. Eutrophication always resulted in reduced mycorrhizal mass. The increased carbon allocation went to the bacterial food web. However, all interactions are highly variable. Moreover, the patterns of allocation varied by plant species, fungal group, experimental design, and soil type.