Since Roman times humans have been pushing back the forest in Switzerland and changing it. As a result there are only a few small areas of virgin forest left. But since local conditions differ so much, Swiss forests vary greatly and over hundred different forest types have been distinguished. The forest is also spreading and today covers 33 % or 13,100 km² of the country. Thanks to the forest's diversity and size, around half of the 50,000 species of plants, fungi, animal and microbes found in Switzerland live in the forest.
This diversity is under threat despite a number of laws and regulations designed to protect fauna and flora. Maintaining diversity is therefore an important goal of Swiss forest policy. This is also a requirement in several international agreements, e.g. the 1992 Rio Convention, to which Switzerland is party.

The Swiss government is pursuing a diversified conservation strategy to conserve biodiversity in the long term, ranging from near-natural forest management to the protection and promotion of threatened species and their habitats and the creation of forest reserves (including forests of special genetic interest) and ecological buffer areas. Threatened species include beavers, otters, capercaillie, hazel grouse and rare tree species.
In forest reserves the natural development of the forest is furthered by a policy of either no management intervention (natural forest reserves) or systematic intervention to promote biodiversity (special forest reserves). In March 2001 the federal government and the cantons specified the goals of Switzerland's policy on forest reserves. Within the next 30 years at least 10 % of the forest area in Switzerland, i.e. 1,310 km², must be set aside as reserves, half of which should be natural forest reserves. Today there are roughly 2,227 reserves covering an area of almost 58,000 ha, i.e. 4.8 % of the forest area in Switzerland.

The largest area (7'497 ha = 13 % of the reserve area in Switzerland) is in the Grisons as it contains the National Park (5'240 ha). Cantons also with significant reserve areas are: Aargau (4'870 ha = 9 %), Schwyz (3'771 ha = 6 %), Zurich (3'537 ha = 6 %), Basel-Landschaft (3'406 ha = 6 %) and Solothurn (3'179 ha = 5 %).