and Ecosystem Carbon Cycling in a Changing World

Abstract Climate change is evident and increases of carbon dioxide concentration (CO 2), temperature and extreme weather events are predicted. To predict the effects of such changes on carbon (C) cycling, the processes and mechanisms determining the magnitude of C storage and fl uxes must be well understood. The biggest challenge is nowadays to quantify belowground components of the C-cycle. Soil respiration accounts for ~70 % of total annual ecosystem respiration. However, the CO 2 fl ux from soil originates from several sources, such as root respiration, rhizomi-crobial respiration, mineralization of litter and mineralization of soil organic matter (SOM). Increasing atmospheric CO 2 concentrations will generally increase plant growth, thus C-input to soil. This higher C-input will be accompanied by higher SOM mineralization due to warming. However, mineralization of more stable pool