Design
The Glandwr Forest Carbon Study was launched in 2020 with the aim to maximise the carbon dioxide removal potential of forests, wherever reforestation is implemented.
- This pioneering research represents a unique ongoing research program between The Carbon Community charity, scientists from Imperial College London, the Royal Botanic Gardens, Kew and a network of over 200 citizen scientist volunteers, collecting comprehensive data from 2021 through 2024 to advance our understanding of carbon sequestration.
- The project examines two types of forestry – broadleaf and conifer – and two nature-based treatments – basalt addition and soil microbial enrichment. The study spans 11.5 hectares and involves eight treatment combinations plus an unplanted grassland control treatment, each of which is replicated eight times across the site in a block design.
- There are 25,600 trees in the study, each plot for the eight treatment combinations contains 400 trees. At the centre of each test plot are 100 trees with individual barcodes which are measured in our annual tree census known as the Big Tree Measure.
- Conifer forest was planted with Sitka Spruce, the most common species used in commercial forestry in the UK.
- Broadleaf forest was planted with a Welsh native species mix of Alder (22%), Aspen (5%), Downy Birch (35%), Wild Cherry (19%), Sessile Oak (13%), and Rowan (6%).
- The experiment was established in October 2020 in Wales, with results captured through to October 2024 for this initial above-ground evaluation on tree growth and carbon storage. It investigates the impact of nature-based interventions:
- Soil microbiome inoculation of 200ml of soil from nearby woodland which was added to the tree roots at the time of planting.
- Enhanced rock weathering, which involved applying crushed basalt to the land (in 2020 at 40 tons/ha prior to planting and 2023 at 24 tons/ha).
Enhanced Rock Weathering
Enhanced rock weathering significantly increased carbon removal, with young native woodlands storing up to 27% more aboveground carbon after four years.
Microbial Enrichment
Microbial enrichment showed the greatest impact on tree growth during the crucial first year after planting, with some species benefiting more than others, particularly spruce and oak.
After four years, the broadleaf trees with microbial enrichment had stored 13% more aboveground carbon than those without this intervention, although the difference was not statistically significant due to high variability in tree growth across the landscape.
Enhanced Rock Weather combined with Microbial Enrichmentt
No benefits were found from combining interventions in the first four years.
The first four years of aboveground data in the Glandwr Forest Carbon Study found no benefit in combining nature based-interventions on tree growth, survival or carbon sequestered. Combining the two treatments created a distinct fungal community, and further research is required to assess the long-term impact.
