Plant a tree: What's the point?

Elm, alder, ash or oak: Tree species that shape our native landscape. But trees not only contribute to a beautiful view - they regulate our climate. They extract CO₂ from the atmosphere and bind it long-term in their biomass and in the soil.

Every time you exhale, you emit carbon dioxide - a gas that is partly responsible for climate change. However, humans and animals need oxygen to breathe it in. And this is produced by plants. An old, healthy tree around 20 meters high provides around 10,000 liters of oxygen every day - enough air for up to ten people to breathe.

The "green lung": CO<sub wg-1="">2</sub> storage tree

Wondering how a tree produces oxygen? Trees photosynthesize in order to grow. To do this, they absorb carbon dioxide from the air. The process works as follows: With the help of sunlight, they break down the gas into its components and turn it into materials they need to form wood. For one cubic meter of wood, a tree absorbs an average of one tonne of CO₂. The by-product of photosynthesis is oxygen. In addition to factors such as size and age, the type of tree is also relevant: A beech or chestnut absorbs around twice as much CO₂ as a spruce.

Trees can also filter dust and particles in the air through their leaves and needles. Every year, the mass per tree amounts to up to 100 kilograms. When it rains, the dust flows down the trunk and directly into the ground. 

Summers are getting warmer and warmer - trees act like air conditioners

It's early summer and the first heatwave is rolling in: The heat doesn't spread, but increasingly clusters in the streets of city centers. Is this the moment when you like to sit under the broad canopy of trees? This is probably because, even in overheated cities, they not only provide excellent shade but also cool air: A single tree evaporates up to 500 liters of water a day. This creates a microclimate directly beneath it and the temperature difference of several degrees can be clearly felt here. The evaporation removes so much heat from the surroundings that the cooling capacity could be compared to that of around ten air conditioning systems. The temperature near the green giants can then feel up to 15 degrees colder. This could help in the future, as experts expect dry summers with extreme heat and periods of drought to become normal in the future.

Reforestation: Trees in the fight against climate change

No one can say which tree absorbs the most CO₂. The CO₂ absorption rate depends on factors such as location, soil quality, water supply, prevailing climate and the age, height, diameter and wood density of the tree. And a single tree alone is not enough to solve the problem of heat and CO₂ emissions. So to combat the climate crisis, we need to plant even more forests. Incidentally, a mixed forest can store more carbon than a forest that only consists of a monoculture. They are also more resistant to environmental influences such as storms or pests.

Despite the great performance of trees and forests, they alone cannot completely remove the amount of CO₂ from our atmosphere. Instead, they shift the tipping points in our climate system into the future. In order to reduce the consequences of climate change even more radically, measures such as reducing emissions, for example by abandoning fossil fuels, are definitely necessary.