The Finnish Natural Heritage Foundation acquired its tenth conservation area in the late year 2005. The Tahjanjärvi Forest has an unusual shape: it is almost a kilometre long, but only about a hundred metres wide, covering nine hectares. The conservation area is bounded by Lake Tahjanjärvi. There have been observations of the flying squirrel living in the primeval-like forest near the unbuilt shore.

Mr Tapio Pohtila, a cheese master and the former owner of the Tahjanjärvi Forest, never touched the tree stand with force: he only picked up some wood to be used at home making it easier to maintain the natural value of the area, which was suitable for the Finnish Natural Heritage Foundation to acquire.

The conservation area shows different kinds of terrain shapes and forest types in an interesting manner. There are heaths and ridges growing pine trees, mossy corners shaded by large spruces, old birches dying in an upright position, swampy hollows, and even a strip of undrained swamp living there. In its diversity, the Tahjanjärvi Forest is a fascinating cross-section of the forest landscapes in the Tammela highlands.