Peatlands are the “kidneys” of river basins. However, intensification of agriculture and forestry in Europe has resulted in the degradation of peatlands and their biodiversity (i.e., species, habitats and processes in ecosystems), thus impairing water retention, nutrient filtration, and carbon capture. Restoration of peatlands requires assessment of patterns and processes, and spatial planning. To support strategic planning of protection, management, and restoration of peatlands, we assessed the conservation status of three peatland types within the trans-border Neman River basin. First, we compiled a spatial peatland database for the two EU and two non-EU countries involved. Second, we performed quantitative and qualitative gap analyses of fens, transitional mires, and raised bogs at national and sub-basin levels. Third, we identified priority areas for local peatland restoration using a local hotspot analysis. Nationally, the gap analysis showed that the protection of peatlands meets the Convention of Biological Diversity’s quantitative target of 17%. However, qualitative targets like representation and peatland qualities were not met in some regional sub-basins. This stresses that restoration of peatlands, especially fens, is required. This study provides an assessment methodology to support sub-basin-level spatial conservation planning that considers both quantitative and qualitative peatland properties. Finally, we highlight the need for developing and validating evidence-based performance targets for peatland patterns and processes and call for peatland restoration guided by social-ecological research and inter-sectoral collaborative governance.

The proper functioning of peatlands depends on maintaining an adequate groundwater table, which is essential for ecosystem services beyond water retention. Most degraded peatlands have been drained for agriculture or forestry primarily through ditch construction. Rewetting through ditch blocking is the most common initial step in peatland restoration. This study analyzed the hydrological response to ditch blocking in three drained raised bogs in Norway (Aurstadmåsan, Midtfjellmåsan and Kaldvassmyra) using a Before–After–Control–Impact (BACI) design. Following rewetting, all sites demonstrated an average increase in groundwater levels of 6 cm across all piezometers affected by ditch blocking. The spatial influence of ditch blocking extended 12.7–24.8 m from the ditch with an average of 17.2 m. Additionally, rewetting increased the duration of favorable groundwater levels for peatland functioning by 27.7%. These findings highlight the effectiveness of ditch blocking in restoring hydrological conditions, although its impact is spatially limited. Future assessments should also address vegetation recovery and greenhouse gas emission reductions to ensure comprehensive restoration success.

The presence of water in a peatland determines its proper functioning and is a prerequisite for its provision of ecosystem services other than water retention. Since the majority of degraded peatlands were drained for agriculture through the construction of ditches, the most common first step in the restoration of drained peatlands is rewetting through drain-blocking. The aim of this study was to analyze the hydrological response of three independent drained raised bogs in Norway (Aurstadmåsan, Midtfjellmosen and Kaldvassmyra) to ditch-blocking. The hydrological response to rewetting as well as the drain-blocking efficiency were assessed based on groundwater level monitoring conducted from 2015 to 2021 as a BACI design (Before-After-Control-Impact). The data was retrieved from water level loggers installed in piezometers placed in several locations at each of the sites. Rewetting technique used in the study sites included blocking the ditches draining the mires with peat dams. In each of the sites points with increased mean groundwater levels after rewetting were observed. It was also found, that the differences in precipitation before and after rewetting had no significant effect on groundwater levels. Both in Aurstadmåsan and Midtfjellmosen most of the piezometers reported an increase in average groundwater levels after rewetting. In Kaldvassmyra, 3 out of 8 piezometers reported an increase in mean groundwater levels. Even though in all sites precipitation was very similar before and after performed rewetting actions, comparison in Kaldvassmyra shows that the period after the implementation of restoration measures was noticeably drier. This might have inhibited the rewetting role of the dams in that site, which shows in the results. Considering the data from all impact piezometers, the groundwater levels increased by an average of 0.062 m. The same value for control piezometers was -0.003 m. The influence range of the ditch-blocking was 12.7-24.8 m, with the average of 17.2 m. Obtained results show that ditch-blocking might be an effective tool in restoring the hydrological conditions of peatlands, although it might be limited by meteorological factors, such as low precipitation. Assessment of the success of restoration should be integrated with the analyses of other conditions, including changes in vegetation cover or gas emissions (CO2, CH4, N2O).