Geråsen, Naturreservat

There are almost five hundred large oak trees in the Geråsen nature reserve, forty-five of which are protected as natural monuments. They stand in the grounds near the main building at Geråsen farm and are marked with a conservation tag. The nature reserve extends both north and south of the road.
Geråsen is located in an open agricultural landscape. There are moraine hills and grazed pastures with old oaks and other deciduous trees. The old trees are home to many insects, lichens, fungi and birds. Among the rare fungi that only grow on oak trees are the breadfruit tick, the pale tick and the coral tick.

Long history

Oak forests have existed in the Viby area since the warm period 8,000 years ago. This has been found out by examining pollen layers in the bottom sediment of Lake Viby. The oak was important to humans for a long time. Right up to the Viking Age, people had a great reverence for old oaks in their religion. This has certainly meant that old oaks have been allowed to remain. Since the middle of the Middle Ages, the king was in charge of the oak trees that were not on freehold land (land owned by the nobility), as they were important for the navy. But when the oaks were no longer needed, many were cut down. They were only allowed to remain on freehold land. There were many freehold estates in the Viby area, which is why the county's most interesting oak groves are in this particular area.

The leatherback beetle

The leatherback beetle (Osmoderma eremita) is a beetle that is adapted to living in hollow oak trees that are older than 200 years. It is one of the beetles included in the Swedish Red List of Threatened Animals and Plants and is considered vulnerable. The leatherjacket belongs to a rich animal community that lives in old oaks that are rotten inside. A further 20-30 species of very rare small animals can be found there, all of which depend on the survival of old oak trees in sufficient numbers. The leatherback beetle spends most of its life as a larva in the so-called 'mulm', the loose inner lining of decaying oak trees. It lives as a larva for about three years and then pupates. At the end of July and beginning of August, the finished beetles emerge. The leatherback beetle is 3 cm long and brown in color. It normally crawls around on the hollow oaks and is most active at dusk. It requires warmth, and warm summer evenings are needed for it to take flight.

Availability

Geråsen belongs to level 1 in the County Administrative Board's leveling of the county's nature reserves, which means that the reserve lacks outdoor recreation facilities.

Read more about the leveling and management of protected nature