Tree species composition
The forest is extremely important for biological diversity in Switzerland: Nearly half of native plant and animal species depend on it. The Swiss landscape would be naturally dominated by beech and spruce forests, which are relatively species-poor. Forests that are rich in different tree species arise either naturally over long periods of time (climax) or through short-term human interventions.
Mixed stands dominate many of today’s forests that are influenced by human intervention. Because species diversity declines naturally with increasing altitude, the forests in the Central Plateau, independent of human activities, are richer in different tree species than forests in the mountains. The diversity of tree species has increased since the mid-1980s.
Most commercial forests consist mainly of commercially viable tree species, such as spruce, fir, beech and ash. The promotion of less commercially competitive and viable tree species increases biological diversity and the stability of forests in many cases. However, forest reserves do not provide an automatic guarantee of diversity and stability.
The indicator is used in the context of the Ministerial Conference for the Protection of Forests in Europe (Forest Europe) and is therefore comparable throughout Europe.
The tree species composition is surveyed using samples taken in the forest, modelled and calculated for the entire forest area and the producing regions.