Below-ground carbon inputs contribute more than above-ground inputs to soil carbon accrual in a bioenergy poplar plantation

Background and aims Soil organic carbon (SOC) accrual is central to the discussion on active atmospheric CO2 removal strategies, but it requires a clear understanding of the mechanisms driving new SOC formation. SOC is formed from the decomposition of above- and below-ground plant inputs, yet their accurate quantification remains a major challenge. In the current study the in-growth soil core and δ13C methods were combined to quantify the net C input from single or combined above- and below-ground parts of a poplar (Populus) bioenergy plantation.