## 3 Literature Review
#### 3.1.2. Peatland Management and Restoration Strategies
Rewegetation can improve carbon sequestration, while in peatlands without a sufficient vegetation layer, soil carbon is reduced; there are also soil erosion risks. Revegetation directly impacts whether peatland rewetting will be considered sufficiently effective in the long term [1; 134]. Restoring vegetation is critical for peat formation processes, and it is possible to restore degraded peatlands [7; 134]. Peatland-typical plants are used in revegetation [3; 134]. In peatlands, where the hydrological regime and vascular plants have been restored, the soil accumulates higher amounts of carbon and organic matter, characteristic of peat soils [7]. Other hydrological regime restoration methods are described in the scientific literature, which are discussed less than peat rewetting with drain-blocking or dam constructions. These methods rely on the slow rewetting [51] or top-soil removal of peatlands before rewetting [70; 87; 88]. When the water table in a peatland is raised over a more extended period, the risk of rising phosphorus concentrations, nutrient leakage, and CH4 emissions is reduced. In the slow rewetting process, the water table is gradually raised, leading to a partial saturation of the degraded soil layer, which reduces phosphorus mobilisation [51]. 3. Topsoil removal of peatlands. To reduce the risks of nutrient leakage and restore nutrient-poor conditions, it is possible to remove the top layer of soil before peat rewetting [39]. This practice is called topsoil removal. After peat extraction, nutrients are most released in pre-drained peatlands and bogs [117; 135]. Top-soil removal methods increase the effectiveness of peat rewetting and reduce GHG emissions. In peatland regeneration and GHG emission reduction plans, topsoil removal is recommended to reduce nutrient release, mobilisation, and CH4 emissions that form after rewetting by first removing the eutrophic topsoil and promoting peat regeneration [70; 89]. The wider use of the method is restricted by high investments and a lack of knowledge. Removing the topsoil before peat rewetting decreases nitrogen and phosphorus levels, reduces the risk of eutrophication and algal blooms, and diminishes DOC, CH4, and CO2 emissions. Studies have estimated that by removing the nutrient-rich topsoil in agricultural lands before rewetting, the risk of eutrophication decreases by 80 to 90%, DOC losses by 60%, and CH4 emissions by 99% [70]. The estimated global warming potential is reduced by 50-70% by first performing top-soil removal [70]. The removed topsoil can be used in agriculture against land subsidence. In general, top-soil removal can contribute to the soil's carbon balance and enhance peatlands' rewetting efficiency [70; 89]. (4)  Afforestation of peatlands  
In the literature, another method of peat restoration is the afforestation of peatlands. It is an efficient way to store atmospheric CO2. Studies have shown that afforestation can reduce emissions, reduce net sinks, and increase tree biomass. CO2 is absorbed and sequestered through afforestation in wood biomass grown in degraded peatlands. The afforestation of degraded peatlands can also improve ecosystem resilience [136; 137]. It is estimated that if the afforestation of previously drained agricultural lands is completed, it is possible to reduce the annual CO2 emissions by 7.8-9.8 tons of CO2 equivalent/hectare [127]. EU member states prefer a vast peatland afforestation of drained and degraded peatlands, insisting that afforestation without rewetting can be considered restoration based on the Nature Restoration Law [. However, some studies indicate that only the afforestation of degraded peatlands is insufficient to restore the peatland ecosystem, return the wetland species, restore habitats, and return biodiversity to the original state [37; 86]. To restore deteriorated peatlands, the hydrological regime must first be recovered [86]. The drained and degraded peatlands emit CO2, and CO2 storage in trees after afforestation does not entirely compensate for these emissions [46; 138].