Welsh forest study finds way to help new woodlands absorb more carbon

Nation Cymru staff

A major new scientific study conducted in Wales has identified two simple techniques that can boost carbon capture in young woodlands, offering a promising new tool in the fight against climate change

Led by researchers at Imperial College London and charity The Carbon Community, the peer-reviewed study found that two simple nature-based interventions – adding crushed silicate rock and soil microbes – can boost carbon capture in young woodlands by up to 27%.

The findings suggest reforestation projects could deliver substantially greater climate benefits without requiring additional land, offering a potential way to maximise the impact of woodlands in Wales and beyond.

The research was carried out in Glandwr Forest, Carmarthenshire. The study is the largest field trial of its kind in the world, with 72 individually managed research plots spread across 28 acres of Welsh hillside – the equivalent of 18 football pitches.

It also represents a remarkable success of citizen science, with over 200 local volunteers working alongside professional researchers to collect annual data from 6,400 individually monitored trees.

Findings from the major peer-reviewed study, published today in Communications Sustainability, show how simple nature-based interventions can increase tree growth in the earliest stages of reforestation.

These interventions have the potential to boost carbon capture by 13% to 27% in the first four years of native woodland establishment.

The Glandwr Forest Carbon Study, led by researchers at world-leading STEMB university Imperial College London and science-based charity The Carbon Community, is investigating carbon sequestration in two types of forest – broadleaf and conifer – with two nature-based interventions – enhanced rock weathering and microbial enrichment, each on its own and in combination.

Enhanced rock weathering is a process that involves applying crushed silicate rock to the soil, while microbial enrichment is a method that introduces beneficial microorganisms from established forests to the soil.

The study is the largest field trial of its kind in the world: 72 individually managed research plots across 11.5 hectares / 28 acres of Welsh hillside, the equivalent to 18 football pitches.

Potential

Dr Bonnie Waring, Imperial College London, said: “What makes this study scientifically striking is not only the potential for carbon removal, but also its unprecedented scale, and the high level of citizen science involvement.

We all need our new woodlands to thrive, for biodiversity, for our wellbeing, and for our climate efforts in the UK and beyond. After just four years, we can demonstrate how each of these simple, nature-based interventions effectively supports the early years of tree establishment and the carbon uptake capacity of new woodlands.”

The results are based on the first four years of the study with initial results focusing on the carbon stored above the ground in the trees. Results for each of the nature-based interventions showed:

Enhanced Rock Weathering (ERW) – Applying crushed basalt (a by-product of mining) to the soil increased carbon removal significantly, with native woodland areas found to store up to 27% more aboveground carbon after four years.

This approach likely improved tree nutrition through two mechanisms: directly releasing calcium as the basaltic minerals weathered, and increasing soil pH, which made existing nutrients (nitrogen and phosphorus) more available to trees.

Microbiome Enrichment – Microbial enrichment showed the greatest impact during the crucial first year after planting, with some species benefiting more than others, particularly spruce and oak.

The results highlight the potential to harness soil microbial communities in the early stages of reforestation and ecological restoration, particularly by optimising inoculum selection.

After four years, the broadleaf native woodland areas with microbial enrichment tended to store more carbon, with aboveground biomass 13% higher than those without this intervention.

‘Critical time’

The project is the result of a long-term collaboration between The Carbon Community charity and researchers from Imperial College London, the Royal Botanic Gardens, Kew, and The University of Sheffield.

It also represents a remarkable success of citizen science, with over 200 volunteers working alongside professional researchers to collect vital data from 6,400 individually monitored trees annually as part of its ‘Big Tree Measure’. This community engagement model has fostered meaningful contributions to climate science and environmental restoration.

Charles Nicholls, co-founder of The Carbon Community, said: “These findings come at a critical time when we must rapidly invest in effective solutions that can tackle both the climate and biodiversity crises.

“These two simple, but promising nature-based interventions could help transform restoration efforts, allowing us to improve tree survival and increase the amount of carbon captured by every tree planted.

“It’s a scientific breakthrough with significant practical implications for the UK’s national carbon removal strategy.”

Professor David Beerling, University of Sheffield, said: “These findings suggest that the addition of a crushed silicate rock such as basalt could be particularly valuable for boosting carbon removal in young native woodlands.

“These initial findings are just the start, with future results investigating the impact on belowground organic and inorganic carbon. We hope others will be able to replicate these interventions to make a considerable difference to carbon removal efforts.”

The Climate Change Committee’s 7th Carbon Budget sets an ambitious target for new woodland creation, aiming for 16% of the UK to be covered in woodland by 2040 compared to 13% today.

To reach this goal, tree planting rates will have to double to more than 37,000 hectares per year. If these simple measures are used as part of meeting these targets, they could help remove an additional 45,000–106,000 tonnes of CO₂ in the first four years of planting alone.