Plant deciduous trees and harvest drinking water
When we plant deciduous trees, we gain more than just living landscapes – we actively safeguard our drinking water. But how exactly is that connected?
More water and life in mixed deciduous woodland
- Deciduous trees lose their leaves in winter. This means that during the rainy winter season in particular, more water reaches the soil.
- Deciduous trees such as beech, oak or maple form a permeable, humus-rich soil layer that can absorb far more rain.
- The humus layer made up of leaf litter and soil organisms filters pollutants and thus also promotes high-quality groundwater recharge.
- Per hectare of deciduous woodland per year, between 500,000 and 1.5 million litres more groundwater can be generated than in pure coniferous forests.
- Structurally diverse mixed deciduous woodlands with site-appropriate species promote biodiversity: up to 1,000 animal and plant species are associated with oak alone, including around 700 insect species
Mixed deciduous woodlands are more resilient than monostructured coniferous forests
- Deciduous trees reflect more sunlight and evaporate more water, which means they reduce temperatures more effectively during heatwaves than conifers.
- The humus-rich soils of mixed deciduous woodlands can absorb more rainwater during extreme rainfall events.
- Mixed deciduous woodlands reduce the spread of pests, as different species are differently susceptible and the balance between pests and beneficial organisms is better.
- The deeper roots of deciduous trees make forests more resistant to storms.
Why coniferous forests are problematic
- Spruce naturally occur in cool, moist mountain regions and pines on sandy soils, but they were also planted in other regions of Germany because of their fast timber yield, with low resilience to diseases and extreme weather events.
- Coniferous forest monocultures allow hardly any light or rain through their canopies.
- Their needle litter is rich in lignin and resin, but contains few easily available nutrients that can be broken down into humus. The soil becomes acidic and low in nutrients.
- The dense canopy, less humus, fewer soil organisms and shallower root depth reduce the water storage capacity of the soils in coniferous forests.
- Monostructured and non-local or non-native coniferous forests harbour less biodiversity and, especially during periods of drought, have little to counter pests such as bark beetles.
Conclusion: Mixed deciduous woodlands are climate-tolerant and fit for the future.
Anyone who plants mixed deciduous woodlands protects the forest, drinking water and biodiversity, also for future generations.
More forest. Water. Values.
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