However, boreal peatland soils contain large amount of C accumulated over millennia in the peat, 13% of the terrestrial C in the biosphere, and any actions that would increase the decomposition of this vast C reservoir have a major impact on global warming.
The utilization of peatland forests causes also pressure on water quality due to the risk of releasing large amounts of organic matter to runoff and drainage water. There is already a widespread evidence for “brownification”, an increase in dissolved organic matter (DOM) concentrations in inland waters. The increase in DOM load has also a major impact on the global carbon cycle as globally inland waters deliver about 900 million - 1 200 million tn C yr-1 to the oceans of which a majority is in organic forms. Part of the DOM is mineralized in the waterways to CO2, CH4 and N2O thus increasing the greenhouse gas (GHG) emissions to the atmosphere.
The aim of this study is to reveal the effect of forest management practices on peatland forests (ditch network maintenance operation (DNM) and forest harvesting) on DOM load and quality and their subsequent effects on GHG emissions in inland waters. We assume that the changes in the growing three biomass and groundwater table affect the decomposition of peat, and consequently DOM load and its quality, through changes in the rhizosphere priming which accelerates the decomposition of peat. The changes in DOM quality, will also effect on its biodegradability in inland waters.
We will study these mechanisms using state-of-the art isotope techniques and water quality measurements and the information will be used to construct a process-based model. We will use the model for estimating the effects of different forest management operations on water quality and GHG emissions and give recommendations on less invasive and more environmentally and climatically friendly forest management options in peatland forests. The work will be done in collaboration with forest ecologists and limnologists providing a unique opportunity to integrate the results from terrestrial and aquatic systems and provide a holistic land-scape level view.
The project is based on three work packages. The experimental part of the research (WP1 and WP2) will be based on field and laboratory experiments for studying the mechanisms underlying the lateral transport of carbon between the soils and aquatic systems and atmospheric greenhouse gas (GHG) emissions, and testing the continuous cover forestry (CCF) in reducing the harmful effects of forest management on GHGs and water quality, i.e. DOM and nutrient load to aquatic systems. Finally, in WP3, the data from the field measurement and laboratory experiments will be used for constructing and developing a process model-based tool for the effects of ditch network maintenance (DNM) and CCF on water quality. For testing the model, we will use long-term field measurement data collected in Finland, Sweden and Estonia.