Supersizing Broadleaves: What Happens When You Combine...

Creating resilient woodlands starts long before a tree is planted. The seed selected, the way a tree is grown in the nursery, and how it is established on site can all influence its long-term performance. Yet despite their importance, many of these factors remain poorly understood in broadleaved forestry.

To help answer some of these questions, Future Trees Trust is continuing its work on the Supersizing Broadleaves project, a research programme supported through the Forestry Commission’s Tree Production Innovation Fund (TPIF). The project explores a simple but important question: what happens when the best available seed is combined with the best growing methods and the best establishment techniques?

The work builds on trials first established in 2023 and is helping generate valuable evidence that could inform future woodland creation and tree establishment practices

Looking Below Ground

While tree growth is often judged by what can be seen above ground, some of the most important differences occur beneath the soil surface.

During winter 2025, researchers returned to three trial sites established as part of the project. Around 400 trees were carefully excavated from each site so that both their root systems and associated fungal relationships could be examined in detail. The assessments focused on oak, sycamore and silver birch and aimed to better understand how different growing and establishment methods influence tree development across a range of site conditions.

By studying root architecture, researchers hope to gain a clearer picture of how young trees respond to different environments and management approaches. Samples were also collected from fine roots to quantify mycorrhizal associations. All trees form mycorrhizal associations which help with water and nutrient uptake and therefore better growth.

As part of the project, researchers are investigating whether bare-root trees have more or fewer mycorrhizal associations than trees produced using other methods. The work will also explore whether glyphosate treatments influence these beneficial fungal relationships and whether any effects may impact tree growth.

Future Trust Researcher James Macintyre and Dan from Forest Research collecting Mycorrhizae

The project has generated a substantial amount of data in an area that has received relatively little research attention. Future Trees Trust is working with statisticians from Forest Research to analyse and publish the findings, helping improve understanding of how seed origin, nursery production and establishment methods influence tree performance.

Dan from Forest Research collecting Mycorrhizae

Building Better Broadleaved Woodlands

Tree improvement is often associated with genetics, but successful woodland creation relies on many interconnected factors. The Supersizing Broadleaves project recognises that the performance of future woodlands depends not only on planting better trees, but also on understanding how those trees are produced, planted and managed.

By investigating these relationships, Future Trees Trust hopes to build a stronger evidence base for broadleaved forestry and help improve tree establishment success across a changing landscape.

Supersizing Broadleaves – Testing the Limits of Tree Establishment

In Birch, Future Trees Trust, Oak, Sycamore

2 Sep