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Puurijärvi-Isosuo

© Genimap Oy, Lupa L4659/02

The Puurijärvi-Isosuo project site (3,619 ha) is located in the areas of Kokemäki and Huittinen towns. The site includes the Puurijärvi-Isosuo Natura area, which is comprised of Puurijärvi Lake, Raijalanjärvi Lake, and six mire areas that are almost in their natural state. In addition, the area includes the Kokemäenjoki River, which flows between the mires and on their edges, as a special Natura area. The majority of the project area is part of the Puurijärvi and Isosuo National Park. The national park is an important nature and recreation area that is visited annually by about 20,000 people. Despite its name, Raijalanjärvi Lake is a cultivated area because the lake was drained for cultivation at the end of the 1930s and the beginning of the 1940s.

The National Wetland Conservation Programme has rated Puurijärvi Lake as an internationally valuable site, and it is also our country's only national park area that includes an internationally valuable wetland. Puurijärvi Lake has also been classified as an IBA area (an internationally Important Bird Area).

The natural environment

Puurijärvi Lake is a shallow, overgrown and eutrophic wetland. Its average depth is only a few dozen centimetres and its greatest depth is under a metre. The lake is nearly completely covered by homogenous helophyte vegetation. The landscape is dominated by common club-rush, common reed, water horsetail and different sedges. At the northern end, abundant bogbean growth indicates overgrowth and bog development. On the shores there are flood meadows and damp scrubland.

Bogbean growth, photograph: Sami Luoma

In Puurijärvi Lake there breed species that are also considered valuable by European standards, such as Bittern, Marsh Harrier, Spotted Crake, Crane and Black Tern. Several dozen pairs of Little Gulls also nest at the lake; 30-45% of the European breeding population is estimated to be in Finland. Puurijärvi Lake is also an important migration-time feeding and resting area, where hunting is not allowed.

Raijalanjärvi Lake is an excellent migration-time resting area for Bean Geese, Whooper Swans and Cranes, especially in the spring. In addition to valuable birdlife, endangered species of mammals are also found in the area - such as the otter and the flying squirrel, which are included in the list of species in the Habitats Directive Annex II.

The area's mires are Southern Finland's most valuable and representative concentrated hummock stringoases. The central part of this kind of mire is elevated from the surrounding area. The centre is barren because it only receives its nutrients from rainwater. The vegetation at the edges of the mire is more lush. The centre is encircled by dry-surfaced hummock strings and pools of water between them. Together the hummock strings and the pools form a mosaic-like pattern. The area's mires have mainly been preserved in their natural state, but in places they have been drained.

The river portion of the Natura area has a very low shore and is susceptible to flooding. There have been wide flood meadows at the riverside in the past, and the parts of them that remain are included in the Natura area.

Published 2014-06-18 at 15:09, updated 2014-06-18 at 15:15