Animals & Nature · Feature
A dead trunk is not simply the end of a tree. As it decomposes, its moisture, structure and nutrient availability change. Fungi, insects and many other organisms make use of different stages in this process. Their diversity therefore depends not only on how much deadwood is present, but also on its form and the periods over which it remains available.
Not every piece of wood is the same
Standing dead trees, fallen trunks, thick branches and heavily decayed wood offer different living conditions. Tree species, diameter, exposure to sunlight and moisture influence which organisms can establish themselves. A newly dead trunk is therefore not ecologically equivalent to the remains of a tree that has been decomposing for years. Some species need particular transitional stages or rare structures such as cavities filled with wood mould. The total quantity of deadwood alone describes this diversity only partly. Whether suitable structures are accessible in the right surroundings is also crucial. A single pile of wood is no substitute for a stand that has developed over a long period, with old trees and different stages of decay. This explains why more deadwood may be important, but does not automatically bring every specialised species back to a site.
Decomposition connects many ways of life
Fungi break down components of wood, changing its properties in the process. Insects feed on wood, fungal tissue or other inhabitants. Cavities and cracks, in turn, can provide shelter or breeding sites. These relationships develop over time and do not form a simple linear sequence. Several processes take place simultaneously and influence one another. The surroundings also play a part: a sunny forest edge creates different conditions from a damp, closed stand. Deadwood is therefore a substrate, a hiding place and a component of food webs all at once. Its value lies not only in nutrients eventually returning to the soil. Equally important are the often lengthy intermediate phases during which structures emerge and change, only then opening up the living conditions that specialised organisms require.
Continuity rather than a one-off deposit
Many species that depend on old wood need suitable habitats over extended periods. When one structure disappears, another must be within reach. Providing deadwood once may therefore achieve less than the sustained development of different age classes and stages of decay. WSL points out that sufficient quantities alone are not always enough. Landscape connectivity and a forest’s history also play a role. At the same time, safety issues must be considered along paths and in places where people spend time. This does not imply a general conflict between safety and diversity, but rather a need for planning that distinguishes between locations. A simple rule applies when observing on walks: do not break wood open or peel off bark. What looks abandoned from the outside may contain a sensitive habitat that has developed slowly.
Sources & further reading
- WSL: Deadwoodwsl.ch
- WSL: Fungiwsl.ch
Written in our own words with AI assistance, based on the sources listed above. The text distinguishes research findings, technical prototypes and established knowledge. This feature is not a breaking-news report.