Management of traditional rural biotopes is a key issue.
Overgrowth is a serious threat for both habitats and species.

SCI (partly SPA)

The acreage is total 49 735 ha, 88 % of that is covered by water. There are lot of islands in brackish water where salin-ity is ca. 0,6 %. The archipelago in the Baltic Sea between Åland Islands and mainland Finland is one of the largest archipelagos in the world. The National Park includes more than 2,000 islands and rocky islets shaped by waves and the ice sheet during the Ice Age. Inside the co-operation area of the park, there are about 8400 islands and islets altogether. The National Park mostly consists of outer archipelago, characterised by windswept pine forests (Pinus sylvestris) on the rocks, low deciduous forests and bare rocky islets which show parts of the 2,000-million-year-old bedrock. However, between the rocks there are hollows with lush vegetation of great diversity.

Two eskers are going through the southwestern side of the area. Together with calcareous habitat types these sandy habitats has significant input for biodiversity.
Large areas of open sea, brackish water, bare outer islets and lush herb-rich forests create the habitat for diversity of plant and animal species. A special feature of the National Park are traditional agricultural landscapes, such as wooded meadows, wooded pastures, dry meadows, coastal meadows and heaths, where the cattle of the inhabitants of the archi-pelago grazes. There are about 3 sq.km. of traditional agricultural landscapes in the National Park. The goal of the Na-tional Park is to protect the ecosystems and the culture of the Archipelago and the traditional ways of utilising the na-ture, to preserve the communities of the archipelago, and to promote environmental research.
Due to the salinity in the brackish water (in the Archipelago about 5-6 per mil), the number of different species living under water is low, but because of abundance of populations of the species, the sea is filled with life.
Read more about the traditional agricultural landscapes of the archipelago
The islands and islets (mostly granite) have been smoothened by continental ice. Between the islands long open sea areas and bays have formed in the numerous fracture zones of the bedrock. The human impact is an inseparable part of the Archipelago. Already during pre-historic times, the rich archipelago flora and fauna offered several alternative food sources for the first inhabitants of Finland after the Ice Age. Through repeated immigrations from the west in the Mid-dle Ages (1000-1300 AD) the people in the area are mainly of Swedish origin. Thus 80% of the people in the area are speaking Swedish. The people in the archipelago have always been forced to combine different sources of income to survive. Small-scale agriculture and animal husbandry has been combined with fishing and trade on the nearby markets in the northern Baltic Sea region. Today, the traditional archipelago sources of livelihood, small-scale farming and fish-ing are strongly declining, while the service industry has become increasingly important. Above all, tourism has gained more significance.
Flora & Fauna
The number of aquatic species adapted to the brackish conditions in the Archipelago Sea is low. The large number of individuals however indicates a vigorous and rich environment. Typical fish species are the Baltic herring, pike, white-fish, perch and flounder. The archipelago is the south-western extreme of Finland and it is home for many plants not found on the continent. It supports the richest pastures bloom with Elder-flowered orchids, Coral wort and Nettle-leafed bellflower. Crab apple trees and Buckthorn occur along the edges of meadows. In the 1920s-1950s more than 600 vas-cular plants were found in the National Park area. Many of these plant species depend on traditional cattle breeding and are therefore threatened today. 122 Species of breeding birds and 24 mammals have been counted in the park. In differ-ent parts of the park one can find for example various gulls, Arctic tern, Eider, Razorbill, Black guillemot, Mute swan, Greylag goose, Shelduck, Arctic skua, Nut-cracker and Barred warbler. Endangered species found in the National park include White-tailed eagle, Caspian tern, Greater scaupduck, Grey seal and Ringed seal.
Plants
The exceptional diversity of the vegetation at the Archipelago Sea arises from the small features of the landscape, and the variety of rock basement. Although the park for most part consists of bare and rocky outer islands, calciferous soils nourished by shell remains and deposits of limestone can support luxuriant groves between the rocks. For example, ash (Fraxinus excelsior) often grows in the hollows.
Around dry pasture meadows grow species such as the Bloody Cranesbill (Geranium sanguineum) and the Swallow-wort (Vincetoxcium hirundinaria). On leaf fodder meadows bloom the Elder-flowered Orchid (Dactylorhiza sam-bucina) and the Nettle-leaved Bellflower (Campanula trachelium), and on the edge of the forest grow the Common Buckthorn (Rhamnus catharticus), and the Crab Apple (Malus sylvestris).
Animals
In the Archipelago area live 25 species of mammals, the most common ones being small rodents. Also large animals, such as mooses (Alces alces), can be seen. Most part of the declining population of the Baltic Ringed Seal (Phoca his-pida botnica) in the archipelago lives inside the National Park. The Grey Seal (Halichoerus grypus ) is becoming more common, and it may turn up to watch boaters almost anywhere in the National Park.
There are 132 breeding bird species in the Archipelago. Gulls (Larus), arctic terns (Sterna paradisaea), eiders (Somate-ria molissima), razorbills (Alca torda) and black guillemots (Gepphus grylle) nest on small bird islets. The mute swan (Cygnus olor), greylag goose (Anser anser) and shelduck (Tadorna tadorna) build their nests in the peaceful archipel-ago, while the arctic skua (Stercorarius parasiticus) looks out on the high rocks.
The nutcracker (Nucifraga caryocatactes) and barred warbler (Sylvia nisoria) live in the shelter of leafy trees. These days it is also possible to see the white-tailed eagle (Halliaeetus albicilla) gliding up in the sky. It has been saved from exctinction by active conservation measures. Threatened species in the area include the caspian tern (Sterna caspia) and a subspecies of the Dunlin (Calidris alpina schinzii).