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 (CO₂) emissions from peatland forests, but despite great interest in its use, information on its effects on forest CO₂ balance is very limited.

We studied the effects of partial harvesting on forest CO₂ balance in two nutrient-rich peatland forest sites Lettosuo (ICOS associate site) and Ränskälänkorpi, both managed with continuous cover forestry. Forest CO₂ fluxes were measured with eddy covariance method before and after partial harvesting (Lettosuo 2010-2022, Ränskälänkorpi 2020-2024). Forest CO₂ balances after harvest were compared with pre-harvest CO₂ 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 CO₂ 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 CO₂ emissions decreased a few years after partial harvesting but results from Lettosuo indicate that the strengthening of the CO₂ sink stabilizes, and the forest CO₂ balance starts to transition towards pre-harvest conditions 6-8 years after harvesting. The results indicate a relatively fast recovery of forest CO₂ balance after harvesting but suggest that nutrient-rich peatland forests managed with continuous cover forestry might still be sources of CO₂ for most of the time.