University of Stirling research is reshaping how woodlands are created across the UK.

A new study, led by Dr Elisa Fuentes-Montemayor, a Senior Lecturer in Nature-based Solutions at the University’s Faculty of Natural Sciences, has identified key ecological factors supporting natural colonisation – where trees are encouraged to colonise new areas naturally without the need for planting.

The paper, which combined findings from researchers and practitioners, also compiled 15 case studies to illustrate that natural colonisation can provide a range of environmental and societal benefits.

Its findings are already influencing national policy and funding schemes.

The National Forest Company – one of the project partners – is developing a new suite of forest creation grants based on the findings, aiming to give land managers more flexibility to use hybrid creation approaches.

Natural England has also adapted its advice to include the use of hybrid approaches as a result of the study.

Tree planting has been the most common woodland expansion strategy in the UK for many decades as a quick and reliable method, and researchers now hope that integrating natural processes into woodland creation strategies will maximise the benefits.

Dr Fuentes-Montemayor, who led the research project, explained: “Despite many benefits, tree planting is increasingly being questioned following overestimates of the positive impact that it can have, as well as challenges in scaling-up at the level required to meet ambitious government woodland expansion targets.

“Consequently, there is growing interest in incorporating natural colonisation – either alone or in combination with tree planting – into woodland expansion strategies. But the outcomes of natural colonisation can be variable, and there is still considerable uncertainty around the ecological processes involved.

“Our results are significant because they identify situations where natural colonisation is unlikely to be successful on its own, highlighting the importance of hybrid approaches (such as low-density or cluster planting) to kickstart woodland creation.”

Dr Susannah Fleiss, lead author of the paper and post-doctoral researcher at the University of Edinburgh’s Centre for Sustainable Forests and Landscapes, said: “We brought together expertise from practitioners and researchers understand key factors of successful natural colonisation, and to identify knowledge gaps that need further research.

“It is important to bring different perspectives together and share experience and understanding, something that unfortunately happens too little, but that was greatly appreciated by both researchers and practitioners.”

As part of the interdisciplinary research project, the team of ecologists compared tree planting, natural colonisation and hybrid approaches that combine the two.

Until recently little was known about the ecological consequences of woodland creation approaches that incorporate natural processes.

Researchers found that woodlands created through hybrid methods offer intermediate values of forest growth and structural complexity, as well as being more biodiverse – with more species of moths and ground flora – than either purely planted or purely naturally colonised woodlands.

Emma Dear of Natural England said: “I think hat we now have a better idea of how this hybrid approach can not only promote natural colonisation by encouraging land managers that it’s a less risky approach, but we also appreciate that it has benefits for nature recovery in and of itself."

The TreE_PlaNat project was a two-and-a-half-year study funded by UKRI’s Future of UK Treescapes Programme.

Ecological surveys took place in the summer of 2023 in 28 woodland creation sites across England; this included a combination of field surveys and the use of drones and LiDAR, a remote sensing technology that uses pulsed laser light to measure distances, to characterise woodland structural attributes.

Social scientists used semi-structured interviews and online surveys, with more than 500 respondents across England, Scotland and Wales, to understand the views of land managers on different woodland creation methods – ensuring that the findings would translate into real world changes.

Dr Fuentes-Montemayor added: “The benefits and trade-offs of different woodland creation approaches depend on land managers’ objectives. Because woodlands created through hybrid approaches offer intermediate outcomes, by controlling how much of a site is left to natural colonisation land managers can direct the woodland creation process to suit their intended outcomes. This allows a balance between biomass accumulation and structural heterogeneity which is highly beneficial for biodiversity.”

Professor Bianca Ambrose-Oji, Chief Scientist at Forest Research, added: “Knowledge and information about how to implement natural colonisation as well as hybrid approaches turned out to be a key factor in encouraging uptake, reducing outcome uncertainty, and demonstrating how different techniques could best suit land managers own values and objectives.”

Creating woodland through natural processes: Current understanding and knowledge gaps in Great Britain was published in the journal Ecological Solutions and Evidence.

A longer report with more detailed information on working with natural processes for woodland creation is available online.

The project was led by the University of Stirling in collaboration with the University of Edinburgh, Forest Research, Royal Holloway University of London, Woodland Trust and National Forest Company. It was funded by the UKRI through their Future of UK Treescapes Programme.

Further information on the project is available on naturalcolonisation.co.uk.