Soil microbial feedbacks to atmospheric CO2 enrichment.

Increased atmospheric CO2 concentration often stimulates plant photosynthesis, enhances carbon (C) allocation below-ground, increases plant nutrient uptake and improves the efficiency of plant water use. Recent studies suggest that microbial responses to CO2-induced alterations in soil C, water and nutrient availability play an important role in determining ecosystem feedback to CO2 elevation. However, to date, most of the published results have been obtained from short-term experiments or from studies using high-nutrient or disturbed soils. Information on microbial responses to CO2-induced changes in natural and/or mature ecosystems with nutrient limitations is critical to predict changes in terrestrial ecosystem C storage under future CO2 scenarios.