Ecological Restoration of Mires
Originally, natural mires covered a total area of 10.4 million hectares in Finland. Today we have about 8.7 million ha, of which some 4.7 million ha have been drained. In protected areas, there are some 1.2 million ha of peatland, and more than 50,000 ha of this had been drained before the mires were protected.
Main threats to all peatland habitat types are hydrological effects caused by drainage for forestry purposes, including the effects of existing and cleared ditches in the surroundings of the mires and in their catchment areas. Drainage and other land use near these sites and their catchment areas have also had negative effects on the hydrological regime.
About a quarter of all native plant species in Finland are associated with mire habitats, while 80 of the country’s approximately 235 breeding bird species are dependent on the continued existence of mires during at least some stage of their life cycle. Fertile, nutrient-rich mires have inevitably been most intensively drained, and the most significant decline has been recorded in the characteristic species of such habitats.
Between 1989 and 2018, a total area of 25,000 ha of mires has been restored in protected areas, mainly on Natura 2000 sites and by Metsähallitus, PArks & Wildlife Finland. Ecological restoration measures for mires usually involve using an excavator to block and dam drainage ditches. It is also necessary to fell and remove trees in naturally open or sparsely wooded mires and along the banks of the ditches to be blocked. Tree removal is essential as trees lose high volumes of moisture through transpiration. Raising water levels in the mire, slowing down water flows, and diverting water to make it flow in a more natural direction are other measures required to restore mires.
A national network of 145 sites has been set up in Finland where the impacts of peatland restoration on hydrology and biodiversity are monitored. The development towards a natural state is very slow after restoration, and it takes time for the hydrological conditions to become near natural. Ecological restoration has had a positive impact on the representativeness of these mire habitats and their populations of vascular plant, moss, insect and bird species so far, but additional measures will be needed to meet the sites’ conservation objectives.
Many of the restoration and management activities have been carried out under several LIFE Nature projects since 1995. Currently, two LIFE projects are ongoing in Finland which target the restoration of wetlands on several sites. Freshabit LIFE will end in year 2022 and Hydrology LIFE in 2023.