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Biodiversity, conservation and primeval forests

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In Switzerland, hardly any primeval forests remain. In order to foster near-natural forests and the species dependent on them, natural forest reserves have been established since the 1990s. We have been tasked with the scientific monitoring of the development of these forests and their fauna and flora.


Primeval forests – forests which have been truly untouched by human hands – barely exist in Switzerland. However, there are many forests that have not been managed for decades. Over 800 of these have been set aside as natural forest reserves, largely without human intervention. We have been studying the development of 49 of these reserves in Switzerland, in cooperation with ETH Zurich, and comparing them with managed forests for many years.

We also cooperate with colleagues abroad to explore the true primeval forests, for example primeval beech forests in the Carpathian regions of Ukraine. This provides valuable comparative data for local natural forest reserves and managed forests.

Far from Dead: Deadwood Habitat

A typical feature of primeval forests, which differentiates them sharply from timber forests, is deadwood. Deadwood originates when trees die, for example due to natural events such as storms, age, diseases and pests, or through competition. In a managed forest, on the other hand, most trees are harvested before their natural death.

The research that we have conducted in collaboration with ETH Zurich demonstrates that natural forest reserves also contain large amounts of deadwood. As a result, they facilitate the survival of numerous species which are dependent on deadwood (= xylobiont). Particularly valuable are larger quantities of deadwood and late degradation stages. In managed forests, there is often not enough of this to meet the demands of xylobiont species. Many are therefore endangered.

These rare species are therefore good indicators as to whether the natural forest reserves really help biodiversity. For this reason, we monitor species of xylobiont beetles and fungi in the reserves. Our research has already shown that the number of rare species of deadwood in forest reserves is actually higher than in productive forests.