Influence of different tree-harvesting intensities on forest soil carbon stocks in boreal and northern temperate forest ecosystems

•Effective governance measures are necessary for sustainable forestry.•There is little focus on governance of harvesting effects on soil organic carbon.•The long-term impact of intensified forest harvesting on SOC stocks is unclear.•Long-term experiments are needed to identify key processes.•Expert opinion can bridge the gap to practical management guidelines.

Effective forest governance measures are crucial to ensure sustainable management of forests, but so far there has been little specific focus in boreal and northern temperate forests on governance measures in relation to management effects, including harvesting effects, on soil organic carbon (SOC) stocks. This paper reviews the findings in the scientific literature concerning the effects of harvesting of different intensities on SOC stocks and fluxes in boreal and northern temperate forest ecosystems to evaluate the evidence for significant SOC losses following biomass removal. An overview of existing governance measures related to SOC is given, followed by a discussion on how scientific findings could be incorporated in guidelines and other governance measures. The currently available information does not support firm conclusions about the long-term impact of intensified forest harvesting on SOC stocks in boreal and northern temperate forest ecosystems, which is in any case species-, site- and practice-specific. Properly conducted long-term experiments are therefore necessary to enable us to clarify the relative importance of different harvesting practices on the SOC stores, the key processes involved, and under which conditions the size of the removals becomes critical. At present, the uncertainty gap between the scientific results and the need for practically useable management guidelines and other governance measures might be bridged by expert opinions given to authorities and certification bodies.