Trees for swales

What is a swale?

A swale is a depression in the landscape that temporarily collects rainwater and allows it to seep gradually into the soil. This prevents flooding, relieves pressure on the sewer system and helps maintain groundwater levels. A swale also contributes to a greener, cooler urban climate and can function as a recreational green space.

Benefits of swales

Swales are being used more and more in urban areas and infrastructure projects. The benefits are significant.
•    Improved drainage: Swales slow the runoff of rainwater, so sewers are less likely to become overloaded and flooding is prevented.
•    Groundwater recharge: The collected water slowly infiltrates the soil, replenishing groundwater. This is good for plants, animals and our drinking water supply.
•    Greater biodiversity: Swales provide a habitat for plants and animals that naturally occur in wet areas.
•    A cooler environment: Water and planting in a swale help lower the surrounding temperature, which is especially welcome in cities.
•    An attractive outdoor space: A well-designed swale creates a greener, more pleasant living environment.

Why plant trees in swales?

Trees play an important role in the ecosystem of a swale. They not only help with water management, but also create a more pleasant living environment. Here are a few reasons why planting trees around swales is a good idea:
•    Water uptake: Trees help absorb and transpire water, so the soil becomes saturated less quickly and flooding is prevented.
•    Soil stabilisation: Tree roots create a strong soil structure and reduce erosion.
•    Shade and cooling: Trees provide shade, helping to lower the temperature in the area and reduce water evaporation.
•    Greater biodiversity: Trees attract birds, insects and other wildlife, strengthening the ecosystem around the swale.
•    Improved air quality: Trees filter harmful substances from the air and contribute to a healthier environment.

Which trees and plants are suitable for swales?

Trees and plants in a swale must be able to cope with both dry and wet periods. Below are some suitable species:
Trees for swales:
•    Alnus – Grows well in alternating wet and dry soils and improves the soil.
•    Fraxinus – Tolerates moist conditions well and has a strong root system.
•    Salix – Takes up a lot of water and is ideal for wet soils.
•    Populus – A fast-growing tree that can cope with both wet and drier soils.
•    Quercus – A strong tree that tolerates both dry and wet conditions.
•    Taxodium distichum – Prefers wet soils, but also grows in drier locations.
•    Nyssa sylvatica – Naturally a swamp tree, but also grows in less moist soils.

There are many more species suitable for swales. Would you like advice on which trees are best suited to your situation? Please contact our advisers. We will be happy to help you choose the right trees for a green, climate-resilient environment!