Role of upland forest soils in regional methane balance: from catchment to global scales (UPFORMET)

This project establishes a basis for reliable methane balance estimates for the northern boreal zone consisting mainly of wetlands and forest upland soils, which belong to one of the key terrestrial biomes in the global context. The results thus provide relevant information for the global carbon balance and climate change studies. Mechanisms behind the high CH4 emissions will be clarified in detail. The role of emission episodes in the total methane balance and carbon dynamics of northern soils will be assessed, and climatic relationships will be built.

Project duration: 1.9.2017-31.8.2021

Funding: Academy of Finland

Consortium: Finnish Meteorological Institute (FMI), University of Helsinki (UHEL), Natural Resources Institute Finland (LUKE)

Objectives:

  • Study the prerequisites for CH4 formation in mineral soil by laboratory incubations and field-scale wetting experiments; link the results to soil chamber and eddy covariance measurements.
  • Utilise multi-year ecosystem flux, atmospheric mixing ratio, temperature, long-term lake water level, soil moisture and precipitation observations to detect the interannual variability in the emission signal from wet mineral soils; establish new eddy covariance measurement of CH4 above a mineral soil forest in Kenttärova in northern Finland.
  • Conduct a fine-scale mapping in one northern boreal catchment to reveal the linkage between the type of vegetation, soil moisture, topographic properties, and methane fluxes along a moisture gradient; upscale these results to a larger area using soil moisture and vegetation data obtained from different type of aerial and satellite images.
  • Study the emergence and magnitude of the emission signal in regional and global scales by utilizing concentration observations in atmospheric inverse modelling.
  • Examine the isotopic signature of methane produced in mineral soil to constrain its contribution to the atmospheric methane budget.
  • Compare ecosystem fluxes and the corresponding climate, land cover and soil data with inverse model results; compare ecosystem and soil chamber fluxes with the observed methane formation rates in different soils.

 

Work packages

WP 1. Methane production of upland soils in field and laboratory conditions (lead: Krista Peltoniemi)

Quantification of the prerequisites for mineral upland forest soil methane production and oxidation in field and laboratory conditions.

Understanding the horizontal distribution of methane production and oxidation potential in the soil profile.

WP 2. Methane flux and concentration measurements (lead: Mika Aurela)

Quantification of the climatic response of ecosystem CH4 exchange for both forests and peatlands.

Novel information on the connections between climate, hydrological conditions, ecosystem fluxes and atmospheric methane concentration.

Isotopic signature of upland forest soil and wetland emissions in the atmospheric 13CH4.

Estimates of the radiative forcing due to changes in soil CH4 emissions and CO2 exchange in wet years.

WP 3. Geospatial data for upscaling (lead: Tarmo Virtanen, Terhikki Manninen)

Implementation of detailed field mapping of the land cover and vegetation types in the studied catchment encompassing the spatial gradient from open mire to upland forest soil through transition zones which have a high potential to produce CH4.

WP 4. Atmospheric inverse modeling of methane fluxes (lead: Tuula Aalto)

Evaluation of new methane concentration and isotope observations and land cover information in estimating regional methane emissions.

New information on northern landscape CH4 emissions and their climatic response.

WP 5. Fusion of different information streams (lead: Annalea Lohila)

Comparison of ecosystem fluxes and the corresponding climate, land cover and soil information with inverse model results, in order to assess the agreement in their interannual variability.

Comparison of ecosystem and soil chamber fluxes with the observed methane formation rates in different soils, in order to estimate emission rates and mechanisms in different environmental conditions.

Combining the remote sensing data of vegetation communities and soil moisture to in situ surface observations and to laboratory and field scale methane production experiments, in order to enable upscaling of flux data to larger geographical areas.

Determining environmental criteria for spatiotemporal hotspots of CH4 emission in non-wetland soils.

Evaluation of the importance of wet upland forest soil emissions in the global, regional and local methane balances.