The nature of Ruissalo

Oaks reflect the history of the island

Special attention was paid to the preservation of oak forests as early as the 16th century, as oaks were a valuable material for woodcarving. From the Middle Ages onwards, felling an oak tree for shipbuilding was punishable by a fine. In 1647, a law was passed that made all oak trees the property of the Crown.

The forests of Ruissalo have been effectively pastured since the 1750s. During the pasture period, oak regeneration was mainly restricted to courtyards, where cattle had no access. In the early 1900s, pasturing was banned in order to ensure the growth of oak saplings. The era of forest pasture is still visible in the Ruissalo oaks in the absence of almost complete generations of oak trees.

Rare species thrive in Ruissalo

The old oak forest is where biodiversity is at its richest. Each species plays an important role in the cycle of nature. Old oak trees hide insects in their trunks for woodpeckers, which in turn create nesting sites for tawny owls, stock doves, yellow-necked mice and Daubenton's bats. In turn, the material piled up in the oak cavities by nesting species creates a habitat for the rarest animal in Ruissalo, the hermit beetle, as well as other beetle species.

During its lifespan of several hundred years, the oak provides a home and food for thousands of species. Around 500 insect species alone are known to depend on the oak tree. Many of these species are endangered. In particular, the old oaks of Ruissalo, which are decaying from the inside, are an oasis where many lichens, mosses, fungi and invertebrates which are rare in other parts of Finland, are abundant.

In addition to the largest surviving oak and hardwood forests in Finland, Ruissalo consists of a variety of habitats, including beach meadows, woodlands, grasslands and bays. This diversity of habitats contributes to the biodiversity of Ruissalo.