Partial cutting of a peatland forest causes less short-term on-site CO2 emissions than clear-cutting

Article: Partial cutting of a boreal nutrient-rich peatland forest causes radically less short-term on-site CO2 emissions than clear-cutting

Authors: Korkiakoski, Mika et al.

Publication: Agricultural and Forest Meteorology

Year: 2023

Wide-spread harvesting of forests growing on drained peatlands is foreseen to take place in Finland in the near future as these forests are maturing. The most common forest management practice in Finland is periodic cover forestry, where the forest is harvested by clear-cutting at harvest age. Continuous cover forestry, where the forest is never clear-cut, but instead timber is collected by cutting a part of the forest at a time, can be used as an alternative to periodic cover forestry. This study researched whether utilizing partial cuttings could be used to mitigate carbon dioxide (CO2) emissions and the consequent climatic impact compared to traditional clear-cutting.

The study was conducted at Lettosuo, a nutrient-rich peatland forest located in southern Finland. Part of the forest was partially cut (74% of the stem volume), and part of it was clear-cut, and CO2 exchange of both areas was measured for six years before and after the cuttings.

It was found that partial cutting resulted in clearly smaller CO2 emissions than clear-cutting, at least in the short term. Before cutting, the CO2 balance of the forest was close to zero, and as a result of both cuttings, the forest became a source of CO2. However, the emissions of the partially cut area were noticeably smaller than that of the clear-cut area. After four years, the partially cut forest became a carbon sink, and the net ecosystem CO2 exchange during the six years following cutting was nearly the same as before. The clear-cut area, on the other hand, continued to produce net emissions during the whole six years, although the emissions decreased with time.

However, the decomposition of peat and the loss of its large carbon storage into the atmosphere cannot be prevented by changing the form of cutting.