## 3 Literature Review
#### 3.1.2. Peatland Management and Restoration Strategies
Rewetting of peatlands in temperate and boreal regions can positively affect the DOC concentrations in freshwater [130]. Despite this positive effect, peat rewetting may cause nutrient leakage in the short term [39] and phosphate ion (PO\({}_{4}\)\({}^{3}\)) mobilisation, which may lead to further eutrophication due to the input of nutrients. There are a few contradicting studies that claim that peat rewetting increases DOC concentrations in waterbodies and promotes an increase in CH\({}_{4}\) emissions [39]. Rewetting is not suitable for all cases of peatlands. The prospects of peat rewetting are influenced by the location of the peat and the need to maintain a regularly high level of water. Rewetting after peat cutting could be a sustainable strategy, as rewetting is often more straightforward when the peat is removed [117, 121]. In the short term, rewetting may have negative consequences, such as degraded water quality in downstream areas or aggravating GHG emissions [106, 117, 131]. Rewetting is also reported to cause slight changes in the chemical composition of the peat. The quality and chemical composition of the water used for rewetting affects the efficiency of the rewetting of peatlands [55; 71]. When water with high phosphorus concentrations is used for peat rewetting, nutrient leakage and eutrophication risks will increase [70; 71]. It is possible to use salt water, brackish water, or freshwater from rivers or groundwater [39]. Peatland management requires striking a balance between CO2 emissions from drained peatlands and CH4 emissions from rewetted peatlands. Before deciding, it is important to consider both the radiative properties and longevity in the atmosphere of CO2 and CH4. CO2 is a weaker GHG with a longer lifetime, while CH4 is a potent GHG with a short residence time in the atmosphere [62]. Despite the environmental gains from peat rewetting, the cultivation of crops (not wet-adapted) and conventional agriculture, in general [20], is hardly possible due to the high water level. The lands nearby are also not functional for agricultural practice [20; 117; 127]. The restoration of rewetted peatlands to their original conditions may not happen instantly; it may take decades. This is especially true for peatlands in temperate climate areas due to substantial disturbance and prolonged drainage. These peatlands are predominantly fed by groundwater, and oxidation occurs during drainage, altering the peat's physical properties. The changes include increased bulk density, decreased porosity, hydraulic conductivity, and storage capacity. These changes, in turn, lead to more substantial fluctuations in groundwater levels. The effects of peatland rewetting have been studied in the field. Among the main gains from rewetting is a substantial decrease in soil subsidence [125], which prevents carbon mineralisation in deep soil [78]. Farmers and landowners receive carbon certificates as financial compensation mechanisms for peat rewetting on their lands, for reducing CO2 emissions per hectare per year after rewetting. Monitoring and reliable measurements are needed to establish emission reductions accurately so that landowners can be compensated [116; 133; 132]. (2) Revegetation of peatlands  
In addition to peatland rewetting, revegetation can be an appropriate measure in peatland restoration [50]. After peat rewetting, revegetation is the next stage to restore the peatland to its initial condition regarding species diversity. Restoring vegetation is also essential to reducing GHG emissions [1; 134]. Planting vascular plants after rewetting can have a positive effect on the reduction of increased CH4 emissions, promoting pumping out CH4 [50]. Scientists have estimated that active revegetation can be a promising solution for introducing sphagnums and lowering CH4 emissions after rewetting [50]. In some studies, it is estimated that rewetting should be combined with revegetation methods after rewetting to reduce CH4 emissions, and without appropriate revegetation, it is complicated to gain emission reduction [50].