Presentation of the construction and costs of Boträsket wetland in Mustasaari Finland. Constructed wetlands will bind nutrients and sediments from drainage waters and provide habitat for wetland bird, waterfowl in particular.
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• The objectives are to Create habitats for wetland fauna, in particular for waterfowl Promote biodiversity, landscape and multifunctional land use Act as demonstrative site of wetland work in the region
• The location
THE COSTS OF THE CREATION OF THE BOTRÄSKET WETLAND
• Total wetland area 6,0 hectares, of which open water area 3,0 ha and 3,0 ha artificial islands, medium water depth about 0,4 m
• Total costs of the creation 32 100 € (incl. VAT 23 %), Life+ Return of Rural Wetlands accounted 100%:– Excavator and tractor works 29 150 €: excavation of channels, construction of the articifial islands,
excavation of 100 m new ditch and landscaping. – Materials 950 €– Wetland planning and field working 2 000 €
• Machineworks conducted by Sven Håkans from Södra Vallgrun, Mustasaari and his team in 13.2.-1.3.2012 and 6.-12.4.2013
• Wetland implementation planning Juha Siekkinen Life+ Return of Rural wetlands in collaboration with Rolf Sund (representative of the landowners) and Södra Vallgrund Jaktförening r.f. (”Södra Vallgrund Hunting Society”), especially Mikael Ehn.
• Wetland management: Södra Vallgrund Jaktförening r.f. • Waterfowl hunting is possible in Boträsket wetland and it is coordinated by the landowner
and Södra Vallgrund Jaktförening r.f. Waterfowl censuses are the basic tool for determination of sustainable hunting levels.
• Waterfowl censusing in environmental monitoring– waterfowl point counts 4 times/year: 2 counts in late spring, 1 brood count in July and 1 late summer
count in the beginning of August (before the beginning of hunting season)– conducted by Södra Vallgrund Jaktförening r.f.
BOTRÄSKET AREA BEFORE AND AFTER THE IMPLEMENTATION• Aerial photo left, photographed in 2009: before wetland implementations the area was open mire
area, where the tickness of turf layer varied 70-150 cm. About 50 years ago Boträsket was partly shallow and open water lake. Then the new ditch was excavated on northeastern site which lead the current flow next to the lake, and gradually during the decades the area began to be hydrated and it turned to swamp-like, wet biotopes
• Aerial photo right, photographed in 2014: After implementation water areas and islands are visible
Water control structure
Artificial islands
New ditch to wetland
Outflow
Ditch, which led water to flow next to the wetland
WETLAND PLANNING IN 2011
• Collaboration in planning started in the beginning of wetland project
• Above: Field planning with Game manager Stefan Pellas and Mikael Ehn (Södra Vallgrund Jaktförening r.f.)
• Left: Arto Rautio and Jukka Pietarila Metsähallitus Natural Heritage Services conducted the topography levelling in Boträsket area.
• Wetland was created by digging 2-6 m wide and 0,3-0,8 depth channels• Excess soil which was digged, was spread around the wetland and partially to the artificial islands
• Water control structure, the overflow dam with wooden wall was constructed to the east side of the wetland by members of Södra Vallgrun Jatkföreningenin 11.4.2013.
• Logs are of Siberian larch for its durable and waterproof qualities.
• The height of wall outlet was sawed to the desired lowest water level. With movable logs water level is possible to increase up to 50 cm and also the dewatering of wetland is possible.
• Finally the wooden wall was sealed with wood tar, which has been used traditionally to seal e.g. wooden boats and it is a pure natural product produced from pine wood.