Observations of climate impacts of cutover peatland afforestation, and peatland forest restoration, in Finland

To achieve the ambitious goals for carbon neutrality, countries ought to, not only reduce the greenhouse gas emissions of the energy, industry, and traffic sectors, but also enhance the carbon sinks of the Land Use, Land Use Change, and Forestry sector (LULUCF). According to the national inventory of Finland under the Kyoto Protocol (United Nations Framework Convention on Climate Change), for the first time in 2021, the LULUCF sector seems to have turned from a net sink to a net source of greenhouse gases (GHG).

There are approximately 4.84 Mha of drained peatlands for forestry, 0.250 Mha of drained peatlands for agriculture, and 0.100 Mha of areas for industrial peat extraction purposes, in Finland. Yearly emissions from the forestry-drained peatlands are 6.0 Mt CO2-eq and from the wetlands 2.2 Mt CO2-eq.

The TURNEE project, funded by The Ministry of Agriculture and Forestry of Finland, investigates the climate impacts of afforestation of cutover peatlands and restoration of fertile peatland forests. Quantification of the total climate impacts of the LULUCF sector, accounting for GHG balances, albedo, aerosol-cloud-climate and water cycle effects, and feedback to ecosystems, is one of the scientific objectives of the Academy of Finland Flagship: Atmosphere and Climate Competence Center (ACCC). The RESPEAT project, funded by the Academy of Finland, focuses on quantifying the potential of boreal peatland rewetting for climate change mitigation including changes in local microclimates through biophysical impacts.

To study the net ecosystem exchange (NEE), we have established two new observation stations: one in 2021 on a cutover peatland at Naarasneva in central Finland; and one in 2022 on a peatland forest at Rottasniitunsuo in southern Finland, which will be rewetted in 2024. The functional idea is based on the SMEAR (Station for Measuring Earth surface – Atmosphere Relations) concept.  

At both sites, carbon dioxide as well as sensible and latent heat fluxes, are measured using the eddy covariance (EC) technique. Methane fluxes are measured utilizing in-situ chamber technique, and with EC method at the rewetted peatland. Biogenic particle formation is measured with neutral cluster and air ion spectrometer. Supporting measurements include upward and downward radiation, soil temperatures, soil heat flux, relative humidity, and air temperature. Geochemical properties and hydrological changes are monitored by extensive field sampling. The vegetation growth is monitored by fieldwork with the assistance of unmanned aerial vehicle based RGB photographing. Long-term climate impacts of peatland afforestation and peatland forest restoration are scaled and modeled using the LDNDC and JSBACH-HIMMELI land surface process models.

The ongoing research projects deliver in-situ data on peatland greenhouse gas fluxes, biogenic particle formation, and surface energy balance providing information on climate impacts of different land use measures of managed peatlands. The results could also steer and prioritize rewetting and restoration actions for maximum impact. This knowledge is crucial in tackling the climate crisis by mitigating the LULUCF sector emissions.