'Rooting' for Climate Change

REWILDING BOOSTS CARBON STORAGE MORE THAN WE THINK

Whilst the benefits of rewilding for biodiversity have been widely acknowledged, biologist Nancy Burrell set out to explore the role that rewilded landscapes play in combatting climate change. However, after discovering that current assessment methods (based on trees grown in plantations and non-herbivore landscapes) were inadequate at Knepp, her family home which she used as case study, she and her team have produced a research paper challenging them. Their recently published findings suggest that we've been ignoring carbon storage underground, in overlooked scrubland where herbivores play a significant role.

In testing how browsing at Knepp affected the biomass balance of scrub Nancy and her team found that the actual root:shoot ratio was four times higher than current models predicted, challenging traditional views that herbivore browsing stunts tree growth and reduces biomass. Rather, their research shows that Trees reallocated their biomass under browsing pressure, potentially enhancing their carbon storage capacity underground in scrubland environments.

After extracting 39 trees across five different species (oak, sallow, hawthorn, blackthorn and dog rose) including their roots, they discovered that trees in rewilded areas below the browse line (less than 2.5 metres) adopted a different growth strategy, concentrating on developing protective mechanisms rather than focusing on height and width.

"An intriguing question to consider is how browsing pressure affects trees' long term carbon storage potential" says Nancy, writing on 29th January 2024 in 'The Applied Ecologist'. "Typically, it is assumed that trees will reach a maximum height, and consequently their carbon storage capacity. But what if browsing delays this growth, and thereby prolongs the tree's role as a carbon sink? Increased investment in root structures and thorny defences could delay a tree's attainment of maximum height, and thus extend its duration as a carbon accumulator."

Further specific investigation of carbon in scrubland species is required as is the development of accurate ecological monitoring and carbon accounting methods - which are essential in understanding the processes of rewilding and their contribution to both biodiversity enhancement and climate change mitigation.

You can read Nancy Burrell's research paper in full HERE.

Picture credits and copyright: Knepp