Structure: Nursery habitats
Nursery habitats are habitats that are used as breeding grounds and surroundings for juvenile stages. Here are some examples of nursery habitats of economically important species in Finland.
GROUSE: FOREST AND MIRE
Sufficient understorey vegetation is very important for grouse species. The most significant plant is bilberry (Vaccinium myrtillus). Clearfellings decrease the cover of bilberry significantly. Both in moist and dry forests the cover of bilberry declined by more than 80% after fellings and had not recovered at all during the twenty year study period. Since 1950s clearfellings have affected over 5.5 million hectares of forest land. Annual clearfelling has been in recent years approximately 130 000 hectares.
Bilberry is abundant in wooded mires and areas where occur characteristics of both mires and forests. These areas have often been drained for more efficient forestry, and quality of the habitat has widely weakened.
Before the Atlantic salmon (Salmo salar) of the Baltic Sea has reproduced in more than twenty rivers in Finland. At the moment, there are only two salmon spawning rivers left that maintain self-sustaining salmon populations. Rivers Tornionjoki and Simojoki both flow in Lapland. Most significant reason for this development has been the regulation of rivers for water power production and flood control. Damming of rivers was very intense from the 1940s till 1970s. Since the beginning of the 1980s new water regulation constructions have been scarce although intiatives have been presented even in recent years. In 2010 more than 1.3 million hectares of lake area has been regulated.
WHITEFISH, GRAYLING, VENDANCE: BALTIC SEA
Whitefish (Coregonus lavaretus), grayling (Thymallus thymallus) and vendance (Coregonus albula) reproduce on clean and open shores in the Baltic Sea. These habitats have been silting and overgrowing due to eutrophication.
FUCUS VESICULOSUS: BALTIC SEA
Fucus vesiculosus meadows are important nursery habitats for many marine fish species. Fucus vesiculosus grows epilithic in shallow waters in the depth of approximately 0–5 metres. Before it used to be found deeper, up to 15 m below surface, but the decrease of light in the lower water layers due to eutrophication has narrowed its range. Fucus vesiculosus meadows inhabit a large variety of invertebrates, stationary fish and juvenile stages of many marine fish species.
Metsäkanalintujen elinympäristön suunnittelu. Suomen riistakeskus. [In Finnish]
Atlantic salmon (Salmo salar). Game and Fisheries Research Institute.
Avointen rantojen siian, muikun ja harjuksen poikasalueet ja viimeaikainen siian poikaskadon todentaminen. Game and Fisheries Research Institute. [In Finnish]
Fucus vesiculosus. Species information sheet. HELCOM / Baltic Marine Environment Protection Commission.
- Updated (18.09.2017)