Continuous cover forestry in drained peatland forests: Effects of harvesting on CO2 balance at two nutrient-rich sites

Greenhouse gas emissions from drained peatlands have received attention in recent years as countries seek to minimize land-use emissions as part of their climate change mitigation efforts. Continuous cover forestry (CCF) has been proposed as a solution to minimize carbon dioxide (CO 2 ) emissions from peatland forests, but despite great interest in its use, information on its effects on forest CO 2 balance is very limited. We studied the effects of partial harvesting on forest CO 2 balance in two nutrient-rich peatland forest sites Lettosuo (ICOS associate site) and Ränskälänkorpi, both managed with continuous cover forestry. Forest CO 2 fluxes were measured with eddy covariance method before and after partial harvesting (Lettosuo 2010-2022, Ränskälänkorpi 2020-2024). Forest CO 2 balances after harvest were compared with pre-harvest CO 2 balances in both sites and with a control treatment in Ränskälänkorpi, and results from the two sites were compared. The results show large variation in the CO 2 balances of the peatland forests, high sensitivity to weather conditions, but similarities between the sites in response to partial harvesting. In both sites, net forest CO 2 emissions decreased a few years after partial harvesting but results from Lettosuo indicate that the strengthening of the CO 2 sink stabilizes, and the forest CO 2 balance starts to transition towards pre-harvest conditions 6-8 years after harvesting. The results indicate a relatively fast recovery of forest CO 2 balance after harvesting but suggest that nutrient-rich peatland forests managed with continuous cover forestry might still be sources of CO 2 for most of the time.