Fungi penetrate through the cuts and change the texture of the wood. The larvae of wood wasps and beetles devour the decomposed wood. The bark of the tree gradually comes off. Now predatory insect species arrive to feed on the initial colonisers. Birds such as woodpeckers also find plenty of nourishment here. The tree trunk loses more and more of its stability and eventually collapses.

The wood, interspersed with fungi, becomes softer and softer. Mosses and algae begin to grow on the surface. The fruiting bodies of the fungi serve as food for minute fungus beetles. Flying tree seeds can also germinate on the moss. In the end the work is taken over by soil organisms. It takes between 10 and 30 years for a beech trunk to be completely transformed into forest soil. The nutrient cycle is then complete.

Many dead wood inhabitants specialise in dying and dead trees and have a very small radius of action. Without these trees they cannot survive. Protected forest areas with a lot of standing and recumbent deadwood play an important role in conserving these species. Sustainable forestry ensures that there is plenty of deadwood in the managed forest. 9% of the wood in the Kottenforst is deadwood.

• The larvae of the Trichius fasciatus beetle feed on dead, rotten wood. The adult beetle eats pollen and prefers the flowers of umbellifers, rose bushes and blackberry bushes.
• In summer the black-spotted longhorn beetle is often found on old tree stumps. This is where it lays its eggs. The larvae develop in the dead wood. The adult beetles feed on pollen.
• The Devil's coach-horse beetle is a short-winged beetle. Larvae and adult beetles feed predaciously and like to look for their prey in the dead wood of rotting trees.
• Because of its colouring, the long horned beetle is sometimes called a wasp beetle. It prefers to lay its eggs in dying oak wood, and more rarely in beech wood. The larvae take two years to evolve.
• Stag beetles are the largest beetles in Germany. They lay their eggs in the ground at the roots of dead and dying trees. The larvae feed on rotten wood and take 3 to 8 years to develop. Because there are fewer and fewer suitable breeding sites they are an endangered species.
• The European rhinoceros beetle colonises very soft, strongly decomposed wood, so-called mulm. That said, it also avoids food sources that humans unintentionally provide. These include sawdust, bark mulch and compost.
• The rose chafer is a typical deadwood inhabitant. Its larvae live in dead wood, which they also eat. The adult beetles feed on pollen and plant juices.
• The Bostrychus capucinus beetle is rare in Germany. It is found on dry tree roots and lays its eggs in hard, fresh deadwood. The larvae bore through the wood and feed on it.
• Hornets lay their nest in tree hollows in soft deadwood. The queens hibernate and build the first honeycomb cells alone in spring. The building material consists of chewed wood fibres. Once the first female hornet workers have hatched, the queen only cares about laying the eggs.