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MILJØFORSK-Miljøforskning for en grønn samfunnsomstilling

BiodivERSA: Restoration and prognosis of PEAT formation in fens

Alternative title: BiodivERSA: Gjenopprettelse og prognose for torv dannelse i myrer

Awarded: NOK 2.7 mill.

The soil contains a lot of life, about half the plant is belowground and plant residues are turned into soil by bacteria and fungi. In wetlands, peat is accumulating because this decomposition process is hampered by low oxygen supply in the wet soil. This creates a specific nature type with its unique set of species, and it also stores large quantities of carbon in the soil. Carbon storage is important because it takes carbon out of the atmosphere and therefore puts breaks on the greenhouse effect. The carbon is quickly lost to the atmophere upon drainage. In Central Europe most wetlands have been drained and/or harvested, and therefore degraded from their natural state. Currently it is attempted to restore some of them by rewetting. Little is known about how successful this is, and what factors determine if it is successful or not. REPEAT aims at clarifying this by investigating belowground life, and how it affects peat accumulation in undrained (pristine), drained (degraded) and rewetted (restored) wetlands. The effect of natural factors (climate, wetland type) and human management (harvest of aboveground biomass) on peat accumulation have been investigated. Study sites where different management can be compared have been identified accoss Europe (in Romania, Poland, Germany and Belgium). Measurments and experiments have been carried out at each wetland site, and samples have been brought to the lab to do more controlled experiments and measurements. The results of this project is important for wetland management, and an important part of the project have been interaction with policymakes and land managers. The data indicate that rewetted sites approach the state of pristine fen peatlands. In the Norwegian contribution to REPEAT we focus on two aspects: computer simulations of processes in fens and measurements of greenhouse gases. In the modelling part we try to describe how microbial decomposition processes differ in waterlogged and non-waterlogged conditions to be able to predict carbon loss with high and fluctuating water table as we find in pristine and restored wetlands. We are using data collected in REPEAT, other published data as well as theory to develop a theory for decomposition under waterlogging. We have been able to simulate the effect of waterlogging on decomposition processes, but results also indicate that the general description we have of microbial processes in soil are incomplete. Greenhouse gases were measured in the water in the peat soil. Concentrations of the greenhouse gases methane, carbon dioxide and nitrous oxide were measured at 13 study sites from Wales to Romania where restored, drained and pristine sites were compared. Nitrous oxide concentrations were small, as the peatlands had not been fertilised. Methane and carbon dioxide concentrations were not so different between the drained, pristine and restored sites. Methane production potentials of the peat from the restored and pristine sites were measured under anerobic conditions over 5 days in the lab. Methane production potentials of pristine and drained sites did not differ, and the potential was the highest in surface soils. Restoration of drained peatland in temperate climate is therefore unlikely to increase methane production, although more peat becomes waterlogged and therefore anaerobic.

REPEAT has resulted in better knowledge on how well rewetted fens approach the state of pristine fens. It has also resulted in increased international cooperation, and Norwegian researchers have been able to learn from experiences in Central Europe.

Belowground biodiversity affect soil functioning, particularly by controlling rates of production and decomposition of organic matter. Peat soils are formed by a long-term net exceedance of production over decomposition. In Europe most peatlands, especially fens, are severely degraded. Little is known about drivers and pathways that determine whether peat formation and related ecosystem services and biodiversity are truly reinstated after rewetting. REPEAT aims to clarify the mechanisms of peat formation in fens by linking biogeochemical processes to soil community structure and biodiversity, as well as to plant belowground traits, and the effect of paludiculture (biomass harvest). The main research question is: How do environmental factors and human management interact with soil biodiversity in determining rates of peat accumulation in undrained and rewetted fens? This project focuses on both the least disturbed and the most disturbed fens and investigates the restorability of the latter ones, while covering all major EU fen regions. To compare undrained, drained and rewetted fens, we analyse ecosystem processes in-situ in four countries, supplemented by ex-situ mesocosm and laboratory experiments. Guidance on biodiversity-driven mechanisms of carbon sequestration and ecosystem resilience is urgently needed. Stakeholders in participating countries will be integrated through workshops, side events, and field days. Endusers at the EU, national, and regional level are identified. A key stakeholder (Wetlands International) is involved as a consortium partner. The project will advance the knowledge base for process-oriented restoration of fens and will directly impact the application of related policy. REPEAT will consolidate the peatland ecology expertise of five institutions covering the most important European fen regions to obtain the best state-of-the-art knowledge fen peat formation processes.

Funding scheme:

MILJØFORSK-Miljøforskning for en grønn samfunnsomstilling