Biochar: The Ancient Practice Making Waves in Climate Technology
In the United Kingdom, we are in the midst of an ecological disaster. Millions of ash trees are infected with ash dieback disease, a pathogenic fungus introduced as a result of non-native ash tree imports. The disease is set to wipe out 80% of our 125 million ash trees.
Because 115 species rely almost entirely on ash trees for food or shelter, there is a real threat of an extinction cascade. This could be the beginning of the end of healthy British woodlands — unless we act quickly.
In Asia, where the fungus originated, the ash trees evolved alongside this fungus and therefore have developed a symbiosis with the fungus where it does not kill its host. In Europe, however, only 20% of ash trees may have any form of natural resistance, and so it becomes pathogenic, killing most trees over a number of years.
Ash trees have been growing on this island for as long as its inhabitants can remember, but because of this pathogen, these trees risk meeting a fate similar to that of the American chestnut tree. Once abundant on the East Coast of the United States, the trees died rapidly in the late 1800s with the introduction of a similar imported fungus, Cryphonectria parasitica — better known as "chestnut blight."
Nearly four billion trees were lost to this blight, and because there is still no cure, this once-prolific source of lumber and food is now functionally extinct in the US. In the UK, we must take every step to prevent a similar disaster — and fortunately, we have identified a potential strategy to do just that.
A glimpse of regeneration — and hope
People in the UK see ash dieback every day but don’t realize it. Ash dieback causes a tree’s leaves to die off from the top down, creating a sparser and sparser canopy until the tree has nothing left to use for photosynthesis. It isn’t typically the disease itself that kills the tree; instead, the disease weakens the tree, giving honey fungus the opportunity to enter. Once the fungus has taken hold, the tree becomes too weak to survive.
Enter biochar, often called “the oldest thing you’ve never heard of.” Biochar is an ancient practice originating from the Amazon rainforest to boost soil fertility. It is now making a comeback as a method of carbon removal and storage, as well as being recognized for its soil functions.
In early 2018, we started a company, Earthly Biochar, with the mission of scaling biochar adoption to the masses. We developed the first biochar kiln sold to gardeners in the UK before exploring alternative uses of biochar.
This led us to Wales, where, in August 2022, we visited a farmer who had been applying biochar to a stand of diseased ash trees on his land. He took us to a tree that had lost 90% of its leaves before a biochar soil mix was applied around its base.
It was now eight months since the treatment, and what we saw blew us away. We had always suspected that biochar could help ash trees fight back against ash dieback, but we had never seen it with our own eyes — until now.
Witnessing a transformation
Although this tree had nothing growing from the tips of the branches, the still-living upper trunk was bursting with a plethora of green shoots.
Sometimes, this sudden growth of new foliage can be deceptive: a stressed tree can produce a large number of new shoots as a response to the disease in a process called epicormic growth. However, this epicormic growth tends to die back in the second year.
Conversely, if the shoots remain alive and show a second year of growth, this can be a sign of true regeneration. Such was the case of the tree we were viewing.
The farmer then took us to see a larger tree with biochar treatment and a smaller tree that did not have biochar applied. The treated tree had an almost full canopy, with rich, dark green leaves waving in the wind. The untreated ash tree was missing 75% of its canopy, with small, pale green leaves struggling to photosynthesize.
At first, this result seemed almost unbelievable. Once I was convinced that I was seeing an incredibly promising solution to ash dieback disease, I weighed how to move forward to implement this solution on a sufficiently large scale.
Because most landowners have more land than money, it would be a struggle for most to pay for the entire cost of the biochar treatment. But that shouldn't be an impediment to treating these trees. Although the ash trees belong to the landowner, we all benefit from the essential ecosystem services they provide.
I decided to create a crowdfunding campaign that would enable ordinary people to sponsor an ash tree, with the money going toward the costs of treating and tracking the health of the tree over time. We were also able to obtain grant funding from Innovate UK (a UK Government grant), which we used to make this a reality.
Mass-felling will prevent genetically resistant trees from reproducing
Typically, land owners are advised to cut down ash trees that have 50% of their canopy remaining if they are next to a footpath, building, or road. Because of this, some cash-strapped local governments are closing roads for ash dieback removal. Yet instead of felling dangerous trees, they’re cutting ash trees that have more than 50% canopy remaining because it is cheaper to cut them all down at once than to do it in a staged way over time.
This is occurring despite the fact that these trees could still have 4–5 years of life in them before they succumb to the disease. And it also means they are preventing the trees that are genetically resistant to the disease from surviving and transferring their disease-resistant offspring into new land.
This is a serious problem. Because 20% of ash trees in Europe naturally hold genetic resistance to the disease, mass-felling trees removes the opportunity for this genetic resistance to be passed on to the next generation of trees.
While some ash trees will need to be felled, it is a crime against nature to fell a tree based on cost savings alone. These cost savings do not take into account the carbon storage value loss, nor the biodiversity value loss associated with an ash tree.
Energy prices are making matters worse. The price of wood chips as fuel tripled when gas prices shot up during 2022. This provided a market incentive for the indiscriminate removal of trees in order to glean the profit once they have been fed through the woodchipper.
Policy reform and sponsor support: A call to protect our ash trees
We are calling on the UK government and Forestry Commission to reassess the strategy on ash dieback disease. A portion of the taxpayer funds for tree planting could be utilized to protect what we already have. The early findings of our biochar treatment trial hold promise for the possibility of helping our native woodlands adapt to the stresses of climate change.
We are also calling on sponsors to help fund the continuation of this essential work. We need to now turn anecdotal evidence into empirical evidence. But this requires long-term, carefully designed trials, and this research will require funding.
Following our trials, in which we applied biochar soil amendments to 100 ash trees across 6 sites in the UK, we have launched a website where sponsors, landowners, and citizen scientists can get involved in this effort to save our ash trees. Watch a three-minute explainer video and learn more on the website.
As a biochar company, we will continue to allocate a percentage of our profits to pay for ash dieback treatment, but alone we cannot do this. With the help of sponsors, improved practices, and better policy, we can fight back against this threat to our forest ecosystems — before it’s too late.
About the
Series:
Who Will Speak For The Trees?
At a time when human economic development is prioritized over the needs of nature, the Who Will Speak for the Trees? series features top reforestation leaders with a broad range of restoration expertise, including climate tech, monitoring, science, finance, media, and more. These diverse voices offer expert viewpoints to instill confidence in how humanity can support nature to deliver a forested future for all living things on Earth. Join us for this ongoing series to learn more about the science of reforestation and how restoring ecosystems is part of a comprehensive climate solution.
