When old trees die, life begins for many other species, according to a new dissertation. Numerous threatened species need dead wood to survive, along with a varied landscape.
Dead wood, meaning dead trees and branches in nature, is vital for about a quarter of Sweden’s beetle species. Many fungal species also depend on dead wood for survival.
Together with microorganisms and fungi, beetles contribute to the decomposition of tree remains, which provides nutrients to the soil and creates habitats for other insects that, in turn, become food for birds and other animals.
However, many of these fungal and beetle species are threatened today, partly because dead wood has become scarce – especially in managed forests. Paulina Bergmark from the Swedish University of Agricultural Sciences (SLU) has examined in her dissertation whether these species are better preserved in landscapes where nature conservation is combined with forestry, often called eco-parks. The state-owned Swedish forestry company Sveaskog established the first eco-parks about 20 years ago, with the aim of supporting species negatively affected by traditional forestry. Today, there are 37 such forests in total.
In five of these eco-parks, Bergmark studied beetle and fungal species living in high-cut stumps. She then compared the results with four areas in regular production forests.
More red-listed species
The eco-parks contained more diverse tree species and good access to dead wood. The production forests had many beetles, but not to the same extent as the eco-parks.
– Generally, we found both more species and a larger number of red-listed species in the eco-parks compared to the production forests, she says in a press release.
The dissertation also highlighted the importance of tree diversity in forests. Different types of dead trees benefit different species, according to Bergmark.
– In the eco-parks’ varied landscapes, there is a larger proportion of forest where both old and young trees contribute to the creation of new dead wood over time. Increasing variation with both deciduous and coniferous trees in different stages of decomposition can be an effective way to strengthen biodiversity in managed forests, she says.