Bexley Charter Oak
In November 2017 Carbon Gold and Apex Tree Surgeons teamed up to treat the Bexley Charter Oak. Less than a year later, we examine how one of London’s most iconic trees is faring…
The London Borough of Bexley’s Tree and Nature Conservation team called upon Apex Soil Solutions and Carbon Gold to see if enriched biochar and deep-soil decompaction could bring the landmark tree back to good health.
Despite having a root protection zone erected, having amenity grade mulch applied every year and even undergoing some light air-spading in the past, the Charter Oak was showing diminishing vitality and a reduced leaf area index. Its leaves were turning pale green, its huge canopy clearance was reducing due to ‘lazy branches’, and the destructive ‘beefsteak fungus’ (Fistulina hepatica) was starting to produce fruiting bodies.
Apex used their cutting edge Geo-Injector to drill down to 1.2m deep all around the tree base. By blasting 100psi of air every square metre around the root collar to the dripline, Apex was able to decompact the soil and create pockets to be backfilled simultaneously with Carbon Gold’s enriched biochar that completely encompassed the root zone.
Biochar is known to boost tree health and vitality by improving the structure, aeration and water-holding capacity of the soil, and also provides the perfect refuge for beneficial microbiology and nutrients. Carbon Gold’s biochar products are enriched with beneficial bacteria, seaweed and wormcasts, and trees treated with it have been shown to improve resilience to ash dieback, acute oak decline, honey fungus and horse chestnut leaf miner.
Nine months later…
In August 2018 the soil-decompaction and enriched biochar have already had a visible effect. Compared to this time last year, the Charter Oak’s crown is denser, its leaves are a darker shade of green, the branches are no longer drooping and all signs of retrenchment have been halted, despite the unprecedented heatwave and drought since spring.
“We weren’t expecting such a dramatic turnaround so quickly, especially with an organic product. We know from experience that chemical treatments and over-fertilisation can have a good short-term effect but actually worsen a tree’s health in the long run, so we were intrigued by the science behind enriched biochar and the geo-injector application process. I have to say, it was the best decision we’ve made in terms of the Charter Oak’s health!” Philip Louis, Tree & Woodland Officer, London Borough of Bexley
