Långrumpskogen is one of northern Sweden's most protected natural forests. The area is 122 ha in size and is located in the middle of the transition between the valley's river and bay sediments. The area is characterized by elongated low moraine ridges, so-called drum lines, with a stand of pine-dominated primeval forest.
A number of insect species thrive in the old forest environment, but they have become increasingly rare as timber production has taken over large parts of the landscape. The two unusual species larger bark flat beetle and smaller bark flat beetle are found in Långrumpskogen, the former is only known from seven or eight premises worldwide. Both species require the forest to be untouched for a very long time. They are therefore only found in neighboring natural forests that have hardly ever burned. Forest fires were otherwise a recurring and important ecological factor in Norrland's forests. Areas with swamps and moist areas are called fire refuges and in such environments you can find rare species of insects and plants.
Långrumpbäcken flows through the reserve and along the brook a belt a few hundred meters wide with swamp spruce forest spreads out. Occasional coarse pines, aspens and dying glass birches are also found. In some cases, lung lichen grows on the aspen trunks. The ground is covered with white moss, carpets of globular cataracts and thick bear moss traps.
