Improving the ecosystem services of nutrient-rich forestry-drained peatlands by adjusting the ground water level (VESI-KHK)

Runsasravinteisten suometsien ekosysteemipalveluiden parantaminen pohjaveden pintaa säätelemällä (VESI-KHK)

Project duration: 1.1.2015-31.12.2017

Funding: Nessling foundation

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

Project description:

Drainage of peatlands for forestry has been a common practice in northern Europe. In Finland, about 20% of all forests grow on drained peatlands, one-third of these growing on nutrient-rich peat. After the drainage, particularly the nutrient-rich sites show large carbon losses into the atmosphere and to water. One option to reduce the adverse environmental impacts of peatland forestry is to moderately increase the ground water level, which should eventually lead to smaller carbon dioxide (CO2) and dissolved organic carbon (DOC) emissions, however at the same time not to enhance methane (CH4) emissions.

In this project the effect of a moderate water level increase on C balance of a forestry-drained peatland is studied at the Lettosuo site, Tammela, southern Finland. A partial harvest, removing the pine trees which compose 75% of the total wood biomass, was conducted in March 2016. Following the harvest, the water level has increased 15-20 cm, which was expected due to the decreased transpiration of trees. At the clear-cut area, established at the same time, a much more radical water-level increase was measured.

In this project we will compare the 5-years long forest CO2 flux and evaporation data, soil GHG flux data, as well as the leaching of C, collected prior the harvest, to that measured after it. We have established smaller control and clear-cut experimental areas within the larger area with partial harvest. At each of these three treatments we will measure greenhouse gas (CO2, CH4, N2O) fluxes with manual and automatic chambers, and DOC fluxes by manual and automatic sampling at  measurement weirs.

Specific research questions:

  1. What is the impact of WL rise on the peat and litter decomposition rate and tree growth?
  2. How are the GHG balances altered following the harvest and ground water level rise?
  3. What is the impact of harvest on the water balance and DOC leaching?

The overarching aim is to test, whether the adverse environmental impacts of a nutrient-rich forestry-drained peatland can be reduced by means of raising the ground water level

 

Map of the Lettosuo site

 

News about the project:

  • 2 January 2017 -20oC predicted for the end of the week. This is a real test for our DOC measurement instrument dumped in a ditch. Will our home-made heater be able to protect the instrument from freezing?
  • 22 December 2016 Last extension collars installed to automatic chambers. Welcome, snow!
  • Summer 2016 Researchers from the Department of Physics (Univ. Helsinki) have been collecting samples of tree CH4 emission and soil concentrations.
  • 6 June 2016 19 automatic water table level loggers installed to existing manual sampling points at the site.
  • 18 April 2016 Two abstracts and poster presentations about CH4 fluxes and carbon balance before logging presented at EGU general assembly in Vienna, Austria.
  • 7 April 2016 Eddy covariance measurements started at the clearcut area.
  • 16 March 2016 The logging at the site has finished!
  • 29 February 2016 The logging at Lettosuo has started and will continue for the next two weeks.
  • 26-27 October 2015 Two abstracts and one poster presentation about the results of CH4 fluxes measured at Lettosuo in 2011-2013 presented at ICOS 4th annual Greenhouse Gases, Science and Society conference in Helsinki, Finland.
  • 22-24 September 2015 An extended abstract written about the results of CH4 fluxes measured at Lettosuo in 2011-2013 to Annual Center of Excellence seminar held in Kuopio, Finland.
  • 24 July 2015 Started meteorological measurements at Letto3 site.
  • 12 July 2015 Started automatic CH4 flux measurements at Letto2 site.
  • 12 June 2015 Started meteorological and automatic CO2 flux measurements at Letto2 site.
  • 4 June 2015 Started automatic N2O and CO flux measurements at Letto1 site
  • 11-13 May 2015 An abstract and a poster presentation about the preliminary results of CH4 fluxes measured at Lettosuo in 2011-2013 presented at NORA-ICOS workshop in Göteborg, Sweden.

2.1.2017