The creation of different soil types depends on the source rock, climate, water conditions and plant growth. Above all the Kottenforst contains stagnosol, or stagnant surface water soil.

This is characterised by a water-permeable layer in which rainwater can easily seep away and a layer that does not allow the water to pass through. When it rains a lot the water accumulates and the ground becomes very wet. Depending on the weather conditions, water soils can be dry or wet.

Stagnosol is often reddish and brightly spotted. This is due to its water content and oxygen supply. If the soil is dry and there is enough oxygen, iron compounds are oxidized and the soil "rusts". If the soil is wet and no oxygen is present, bacteria convert the "rust" back into energy, and light areas are formed: the soil "bleaches".

After trees have drilled their roots into the ground, they grow in thickness. They anchor in the soil like dowels when a screw is screwed into the wall. This anchorage is so good that the roots only need to make up a small part of the tree's total weight. In the soils of the Kottenforst, heart and tap roots provide particularly firm stability because they penetrate the water-permeable layer. Beech trees have heart roots, oak trees have tap roots. Trees absorb water and nutrients via their root tips.

Earthworms eat their way through the earth. In the process they pick up plant remains and tiny pieces of stone. With the help of the stones, they crush the plant remains and then digest them. Every day an earthworm eats about half of its own weight. It then releases the digested material again. This has turned into nutrient-rich humus.

Earthworms not only make the soil more fertile. They rummage through it and aerate it. The more earthworms, the better! Count how many earthworms live in this square metre of soil!

Moles are perfectly adapted to life underground. Their front feet look like shovels. They use them to dig passageways through the ground. They pile up the earth at the surface to molehills. Between the corridors there are living chambers, which they furnish with leaves and moss as sleeping places or for raising their young.

Moles have very poor eyesight. However, they hear well and have an excellent sense of touch. Their small trunks are very sensitive. This enables them to track down earthworms, insects and spiders on which they feed. If necessary they also look for food on the surface when the ground is frozen in winter. They do not hibernate.

Plastic doesn't belong in the soil. Unlike organic substances such as plant residues it cannot be completely degraded but only crushed. Pieces of plastic become smaller and smaller due to mechanical and chemical decay as well as weathering, until they eventually become microplastic. Many toxins are deposited on the surface of these tiny plastic particles. People are still investigating how exactly this affects living organisms in the soil and the forest ecosystem. Today we already know that earthworms, which absorb plastic particles along with the soil, do not grow as well. Therefore, please do not leave plastic waste in the forest!