Decrease of dead wood threatens wood-dependent beetles
A recently published IUCN report states that about 18% of the assessed European saproxylic beetles are at risk of extinction. This can be led back to an ongoing decline in large old trees all across Europe. Saproxylic beetles are beetles that mainly live on dead wood. Therefore, old and dead, decaying trees play an essential role in saproxylic beetles lifecycle’s. They highly depend on these habitats at least in parts of their lifes. These beetles are furthermore involved in decomposition processes as well as the recycling of nutrients in natural ecosystems. In addition, they are a major food source for birds and mammals. Some species also contribute to pollination.
Please also read: Good Forest Means Dead Wood
Threats for wood-dependend beetles
Saproxylic beetles highly depend on dead or decaying wood. Consequently, the loss of trees across Europe can be seen as the main reason for the decline in their populations. Further contributing to this are tree age structure gaps and degraded landscapes. Such degraded landscapes are not favourable to tree growth. The post about the IUCN report states Stictoleptura erythroptera as an example. This species depends on large old trees with hollow spaces. The continuing loss of old trees across its range is the main threat to this species. It was assessed as Vulnerable.
The project also identified urbanisation, touristic development and an increase in the frequency and intensity of wildfires in the Mediterranean region as major threats. Logging is another factor minimising habitats for these species. In particular, logging of old forests, which host a lot of old and standing dead trees. A recent example for this, is the illegal logging of the Białowieża old growth-forest in Poland.
Further monitoring is needed to discover whole extent of species development
However, the report highlights that there still is a lack of data for many species. According to Keith Alexander, IUCN Saproxylic Beetles Specialis Advisor, the population trend of half of the species assessed remains unknown. He further states that about a quarter of the assessed species showed Data Deficiency. Keith Alexander sees this as a strong sign that more monitoring is neccessary.
Conservation strategies for saproxylic beetles in Europe
The IUCN report recommends the development and implementation of conservation strategies for the European saproxylic beetles that show the highest risk of extinction. Member states should adopt the best habitat management practices. Non-intervention management is an effective management measure to increase dead wood. This management measure consequently contributes to new habitat for these beetles. Another important point stated in the report is the raising of awareness about the importance of dead trees. In particular, for the conservation of beetles that depend on them. Luc Bas, Director, IUCN European Regional Office says:
“It is critical for the Common Agricultural Policy to promote the appropriate management of wood pasture habitats containing veteran trees across Europe. Currently, management practices lead to the transformation of wood pastures into either woodland or grassland. Such a transformation destroys the essential vegetation mosaic many saproxylic beetles need.”
I wonder why those who are concerned about saproxylic beetles, and as a bad example cite Białowieska Forest (where in fact most of those species managed to survive), do not object first – forest practices in Germany where they do not leave practically any dead wood at forest floor.