Wetlands

Nearly a quarter of Sweden’s original wetlands have disappeared as a result of drainage and cultivation, and many of those that remain are profoundly affected by human activities. Many plants and animals depend on wetlands. Nearly fifteen percent of the species on the Red List of Threatened Species are found there.

Drainage by the forestry industry accounts for just over half of the lost wetlands, while a further 40 percent were converted into farmland by drawing down the water level of lakes. Proportionally the greatest number of wetlands have been lost in the plains of southern Sweden: in Skåne and Mälardalen only about one in ten remains. Relatively small numbers overall have been lost to peat cutting, but peat is widely harvested in the counties of Jönköping and Västra Götaland.

Even after these losses, Sweden is still one of the most wetland-rich countries in the world. The largest wetland regions are found in the forested areas of Norrland.

Human impacts continue

The surviving wetlands mostly show varying degrees of human intervention—principally drainage measures to gain land for farming or to increase forest production. In southern and central Sweden there are traces of past peat harvesting in many places.

Many valuable wetlands are subject to encroachment from nearby towns and from the construction of new roads, railways and airports.

Wetlands have an important role to play in preserving biodiversity. Many plants and animals depend on wetland biotopes, and nearly fifteen percent of Sweden’s threatened species live in peatlands or on freshwater margins.

Hydrological changes and plant invasion in wetlands adversely affect the animals and plants that live there. Plant invasion in drained mires is a big problem for many bird species and for the plants and animals displaced by the invaders. Invasion of wetlands can also be caused by the release of plant nutrients on neighbouring lands through forestry activities. Nitrogen deposition is a contributing factor to vegetation changes in some regions.

On the other hand, reduced exploitation of wetlands can itself be a threat to biodiversity. Wetlands that were dependent on regular harvesting and grazing have been lost to plant invasion as their traditional use declined in the course of the 20th century.

Contact: Johan Abenius, johan.abenius(a)naturvardsverket.se