Terrestrial ecosystems exchange vast amounts of C with the atmosphere between the processes of gross primary photosynthesis (GPP) and ecosystem respiration. As such, land surface processes that affect the balance between photosynthesis and respiration should affect the atmospheric concentration of CO2. Because atmospheric CO2 concentrations have been stable over millennia during the Holocene, it can be hypothesized that any process that has affected one biospheric C flux component has been compensated by changes in the other component. However, human activities are causing a net release of CO2 into the atmosphere, which is altering the C flux balance between global GPP and terrestrial ecosystem respiration. Reliable predictions of direct effects of CO2 and related climate forcing factors on vegetation and their feedbacks on the climate system depend deeply on our understanding of this global photosynthesis-ecosystem respiration balance. Tremendous progress has been made on understanding the photosynthetic flux of the terrestrial biosphere, but our understanding of the respiration flux and its components has advanced at a much slower pace [1]. As the majority of the ecosystem respiration flux originates from soils, understanding plant and soil biota interactions in terrestrial ecosystems represent a major challenge for climate predictions. Belowground processes are complex and govern major feedbacks between the terrestrial biosphere and climate. Here, we identified two major belowground biogeochemical processes that have been elusive to ecosystem scientists
