Applying continuous-cover forestry on drained boreal peatlands; water regulation, biodiversity, climate benefits and remaining uncertainties

Continuous-cover forestry (CCF) is increasingly argued as an alternative to clear-cut harvesting in managed boreal forests to improve water quality and quantity, biodiversity, and carbon sequestration. We review the empirical evidence for the potential benefits of CCF on drained forested peatlands in boreal ecosystems as an alternative to conventional clear-cut harvesting. We also discuss possible risks and uncertainties that need further consideration and highlight unanswered questions that need to be resolved before large-scale implementation. In general, we found that the ability to maintain forest production on drained forested peatlands primarily depends on water regulation of the groundwater (GW) table. Currently, the problem with high GW is typically solved using ditch cleaning, but if CCF is adopted, it could be an alternative approach to manage GW without the need of disturbing this already extensive artificial channel network. Implementation of CCF could lower the risk of extreme flooding and droughts, in addition to maintaining water quality and potentially enhancing the carbon sequestration conditions. Furthermore, it could provide a compromise between industrialized forestry and peatland restoration to better meet these targets. However, several important uncertainties remain regarding the potential for natural regeneration in northern latitudes, the net effect of different types of soil damage due to repeated use of heavy machinery, and consequences of climate change that could result in enhanced storm felling. We primarily focus on Swedish conditions, but also evaluate implications in an international context and propose ways to close remaining knowledge gaps.