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Wetlands for Nature and People

Last changes: 2019-01-30

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Raised bog

Raised bog. Photo: Nial Benvie/imagesfromtheedge.com.
 
Raised bogs are characteristic of high moisture, specific vegetation and accumulation of peat. Water in a raised bog is as much important as blood in a living organism. Without proper moisture content a raised bog cannot exist. In raised bogs, the keystone species are sphagnum mosses. Sphagnum has a unique ability to accumulate up to 20-25 times more water than its own mass, thus helping to preserve the moist environment of the bog. Also other raised bog plants, e.g. cranberries and cloudberries, require lots of moisture and specific conditions, therefore they can be found only in raised bogs.
In a raised bog, the peat accumulates when the sphagnum gradually dies. The raised bog environment is moist and acidic, the microorganisms lack oxygen and thus the decomposition of organic matter is very slow. The dead plant debris accumulates and forms peat.
The raised bog peat is used as fuel for burning (because of low mineral content), as litter in farming (because of high capability to accumulate moisture) and in gardening. Peat is a renewable resource, however, it should be used carefully as its formation is a very slow process. Averagely the peat layer accumulates about 1 mm per year. This means that one metre thick layer of peat can be accumulated in thousand years, while its extraction happens much faster – in few years.
 

 
Due to high moisture and acidity in a raised bog, many plant species have developed special adaptations to survive in the hostile environment. For example the carnivorous sundews uptake the nutrients by ‘hunting’ insects, which get trapped on their sticky leaves.
Photo: Agnese Priede.
 
Why should we save the raised bogs?
In Latvia, the raised bogs cover about 4.2 % of the country. Most of them are affected by drainage and peat extraction causing hydrological changes. Therefore the drainage-affected raised bogs overgrow with forest, and the peat layer decomposes.
In Latvia raised bogs are still a common element of landscape, while in many parts of Europe the raised bogs areas have decreased by up to 90 % over the last century.
Raised bogs are home for numerous species that cannot be found anywhere else, e.g. European Golden Plover and Wood Sandpiper.
Untouched active raised bogs and degraded raised bogs still capable of natural regeneration are included in the list of habitats protected under the European Union Habitats Directive. Latvia as a member state of the European Union has undertaken the responsibility on ensuring good conservation status of these wetland habitats.
 
Untouched raised bog. Such bogs are open, criss-crossed with wet hollows and bog ponds. In untouched bogs the plants, e.g. sphagnum mosses, sundews and cranberries, have adapted to very wet conditions and cannot survive in other habitats. Photo: Agnese Priede.
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