Urban Trees

Urban trees are known to improve air quality, biodiversity and mental health. Despite this, planting in towns and cities is lagging behind need as it is
often seen as expensive and hard to establish trees in these environments. We wanted to test if new ideas could be cost-effective and yield a high survival rate.

This pilot is led by: Kent County Council

About the pilot

One method of urban tree planting that is relatively new to the UK is a method of rapid tree establishment inspired by Japanese botanist Dr Akira Miyawaki. This project trialled an adapted Miyawaki method at 16 sites across four participating local authority areas.

The experimental Miyawaki plots were planted alongside control plots, which used the local authority’s standard practice planting, and results compared. Our research has shown that it is possible to cost-effectively establish fast-growing thickets of trees, even in areas of degraded soil quality.

“We’re looking at this amazing difference between the two halves of the site, the Miyawaki and the control next to it, and the difference is astonishing!”

Jon Stokes, Director of Trees, Science and Research, Tree Council

What is the Miyawaki method?

The Miyawaki tree planting methodology proposes a way of establishing trees with the potential to withstand some of the pressures facing urban planting. Developed by Japanese botanist Dr Akira Miyawaki, the method’s original objective was to restore native forests on deforested or degraded land.

The method has since formed the basis of the ‘micro wood’ concept, where small urban plots of land can be densely planted on poor or degraded soil with a variety of native tree and shrub species to create biodiverse woodland habitats. At the time of project inception, there was only thought to be one such plot in the UK and it was therefore a concept that required practical research.

“The Miyawaki method involves making sure the soil is healthy, aerated and with good nutrient content, then planting densely, varied native trees suited to the site. ”

Jackie Shallcross, Tree Council

Watch our video

This pilot focuses on tree establishment and survival but we are also gathering information about tree growth, biodiversity and soil.

Watch video

Read the full report

Download the PDF →

Learning

Survival rates seem to be very high in comparison to control plots, somewhere in the order of 79% compared to 47%, and clearly growth is much faster.
So far, Miyawaki establishment costs (so, including all the materials, planting, watering, combined with tree survival rates) are about 30% of the total cost of the control plots, due partly to their higher survival rates. We experienced a drought in 2022 and the Miyawaki plots remained green and lush in comparison to the control plots.
Urban trees face a variety of establishment challenges, and there can be a lot of competition for the underground space. At phase one of the urban trees pilot a report was commissioned which helps us to understand more about the potential conflicts between trees and utilities. The full report can be found in the resources below.

Next steps

Building on what we have learned so far, we are now testing which parts of the method might be more successful than others, for example just high-density planting, different soil preparations and mulch materials.

We also are testing whether elements of the method can be utilised in other settings, such as in urban hedgerows and for street trees.