UK forests could store more carbon than first thought

British forests could store almost double the amount of carbon than what previous estimates suggest, a new UCL study has found.  

An international team of scientists used 3D scanning to analyse the amount of aboveground biomass (AGB) of 815 trees in a UK woodland to calculate how much carbon they could store.  

The results were 77% higher than previous estimates which could have huge implications for the role of forests in tackling the climate crisis. 

Study co-author Professor Mat Disney, from UCL Geography and the National Centre for Earth Observation, said: ‘Forests currently act as a carbon sink in the UK. However, whilst our finding that the carbon storage capacity of typical UK woodland could be nearly double what we previously thought might seem like a purely positive outcome, in practice this means that for every [hectare] of woodland lost, we’re potentially losing almost twice the carbon sink capacity we thought. 

‘This has serious implications for our understanding of the benefits of protecting trees in terms of climate mitigation – and deforestation and afforestation targets more broadly.’  

The team beamed a 1.4 hectare of Wytham Woods in Oxfordshire with laser pulses through 3D terrestrial laser scanning (TLS) to capture tree structures and the environment in 3D.  

Using statistical modelling, they then calculated the mass and volume of the trees and worked out the carbon storage capacity of the area, comparing the results to previous models.  

Findings raise doubt on previous estimates of forest carbon storage in the UK which seem likely to have underestimated the biomass capacity of woodland.   

Lead author, Professor Kim Calders from Ghent University, said: ‘Currently, most estimates of forest carbon stocks are based on simple allometric models that assume that a tree’s size and mass increase at a steady rate. Our findings show that relying on these models is problematic, as they are not representative of UK forests. While the models work well for trees smaller than around 50 cm in diameter, which are fairly uniform in terms of their size and volume, this isn’t what we see for larger, heavier trees. These are far more complex when it comes to structure – and they vary hugely across place and species. 

‘It’s vital that we’re able to reduce uncertainty in forest carbon estimates, given that land use, and forest protection and restoration in particular, constitute a quarter of countries’ current commitments to their Paris Agreement targets.’ 

Photo by Marc Pell