The protected linden grove of Koivumäki is in the Vaarala city district, in the southeast corner of Vantaa. The linden grove is a protected environment type determined in the Nature Conservation Act. Naturally born linden groves are usually small in size and rare in Vantaa.
The Koivumäki linden grove is in a very typical place; on the bottom of a tall rock cliff, where nutrient-rich soil has grown gradually, thanks to the rock matter eroded from the cliff. The hill also has large boulders.
The…conservation area has about 30 large small-leaved lindens. In Finnish, linden trees are also known by the name 'niinipuu', bast fibre tree. Bast fibre used to have significant financial value, as ropes were made of the tough bast fibre extracted from the tree bark. Bast fibre was also made into dishes, rugs and load coverings.
Despite its name, the dominating tree species in the Koivumäki - 'birch hill' - linden grove is spruce. The trees have grown to be quite impressive in size. The dense trees shelter a shrub layer with multiple species, including typical grove plants such as bird cherry and mountain currant. The most plentiful and visible plant on the forest floor is lily of the valley. The foot of the rocky cliff is a great habitat for male ferns and common polypodies, which remain green all year round. Herb-Robert can be found growing on the rocky hills. This plant has a bad odour, and it is easy to recognise it as a close relative of the more familiar wood cranesbill by its flower.
The conservation area's size is about 0.7 hectares. It became a conserved area in 2002. Koivumäki linden grove is fairly challenging terrain due to dense vegetation and the occasionally steep hill. The small conservation area has no pathways.