Station 6: Water in the forest

The water cycle

The water in our forests is in a constant cycle: water evaporates, the water vapour rises and forms clouds from which rain falls. This forms lakes, rivers and streams and flows back into the sea. The water evaporates again from the water bodies. The cycle begins again.

Clouds -> precipitation -> bodies of water -> groundwater -> bodies of water – water vapour -> clouds ...

Like a giant sponge

The forest floor acts like a sponge. It absorbs the rain. Small spaces in the soil fill with water. Plants and trees draw water from these spaces through their roots. The water in the forest floor is an important reserve for dry periods. Because the forest floor stores a lot of water, it protects us from flooding during heavy rainfall.

Forest soil as a water reservoir

The forest in the water cycle

Rain or snow falls on our forests from thick clouds. This is also called precipitation. Some of it evaporates immediately on the leaves or bark of the trees. Sometimes you can see the water vapour. Most of the precipitation seeps into the forest soil. In the soil, the water is absorbed by the roots of plants and trees. The roots transport the water through the trunk and branches to the leaves. The leaves need the water for photosynthesis.

Forest steaming

Precipitation -> Seepage -> Water absorption via roots -> Transport in the trunk -> Evaporation -> Precipitation ...

Thirsty trees

100 square metres of mixed forest consume around 400–900 litres of water per day. On a warm summer's day, a large beech tree consumes and evaporates up to 400 litres of water from the forest floor. A birch tree consumes and evaporates up to 1,000 litres of water on a warm summer's day.

Like a giant filter

Rainwater seeps deep into the forest floor through the various soil layers. In the process, it is filtered and purified. This turns it into clean groundwater, which can eventually flow from the tap in our homes.

Precipitation, topsoil, subsoil, seepage, groundwater

Climate stress for forests

Climate change, with its heat and drought, is putting stress on our forests. They are dying of thirst or being destroyed by pests such as bark beetles. Mixed forests with different tree species that are better adapted to drought are the forests of the future.

Healthy mixed forest

Climate impacts in the forest