The Orshinsky Mokh peatland is situated in the Kalinin District of the Tver Province, 20 km from the city of Tver. It is a raised bog covering over 68,000 ha to zero peat depth in the watershed area between the rivers Volga and Medveditsa. The peatland has been used for peat mining for 60 years. First surveys were carried out in the 1920s. Originally, peat was extracted by means of hydraulic harvesting that gave way to milling in the 1950s and 1960s. As a result, one-third of the peatland is cutover fully or partially. In recent decades, peat has been extracted on an insignificant area, while the remaining drainage ditches have deteriorated. Earlier peat extraction sites have grown over and partially paludified. Beavers contribute to paludification by damming runoff from the peatland. However, revegetation is limited due to regular fires.
The peatland is located on the national forested lands. The Tver Province Administration and the Ministry of Forestry have expressed their interest in rewetting degraded peatlands.
The Restoring Peatlands in Russia Project has significantly contributed to the restoration of Orshinsky Mokh. During five years (2014–2018), rewetting activities were implemented at six sites totalling 6,450 ha within the peatland area. These were abandoned peat extraction areas divided into milled fields by drainage ditches.
Rewetting designs for these sites were developed by experts from the Peat Institute of the Tver State Technical University (the expert team headed by Prof. V.V. Panov), and the ‘Diakar’ Company was responsible for the implementation of rewetting activities.
All activities related to the field studies, design and implementation of rewetting at the three primary sites covering 3,250 ha were funded from the Project. The rewetting at the three posterior sections (3,200 ha) was funded by the Project with partial co-financing from the Diakar Co Ltd. The total costs of rewetting at Orshinsky Mokh comprised 2,300 RUB per ha.
Rewetting was provided by blocking active field ditches with fixed earth dams at smaller ditches and bypass-dams on larger ones. On higher channels, dams with one-sided or bilateral flow were constructed. The dams help to raise the water tables along the drainage network, thus increasing peat moisture content to fire-safe levels, and promoting mire vegetation growth. The main idea of building the dams is to prolong gradually, in accordance with a positive water balance of the rewetting site, the water runoff period on the site from several weeks to 2-3 months in spring and 1-2 months in autumn. This period should become ever longer, which will result in a steady growth of peat moisture content to its natural values.
The ultimate goal of rewetting is to restore degraded peatlands as closely as possible back to their natural state. A complete restoration may take 5 to 20 years depending on the site’s location. In 10 to 15 years, however, the peatland will perform natural functions typical for mire ecosystems, such as water regulation, gas regulation, and water purification. By that time, original or near-original vegetation communities will form, the peat formation process will resume, and a near-natural biodiversity will restore.
The rewetting schemes were calculated for all sites so that the increase of ground water levels in adjacent areas did not affect the settlements and agricultural lands.
Traditionally, the peat extraction area has been used by local people for collecting berries and mushrooms, for hunting and fishing, as well as for car and motorbike tourism. However, these very types of peatland use cause fires, and so, should be restricted.
Looking forward, the rewetted area may compensate for the lost advantages of peatland use through spreading cranberry and blueberry fields, growing numbers of waterbirds, etc. And, most importantly, the fire hazard will decrease in the area, which will make it more attractive for housekeeping and nature management in adjacent areas.