Losing the Ashes
Dieback threat to UK tree stock looks likely to wipe out a third of all trees.
Environment and Woodland Advisor Mike Dyke of H&H Land & Estates looks into the history of this deadly disease which will transform Britain’s countryside, and what can be done to fight back.
Open-grown in a parkland setting, amongst the trimmed hedgerow and within many of our native broadleaf woodlands, the Ash is easily recognised by its distinctive leaves. Ash leaves are “pinnately compound”, meaning there are (usually) 5 or so symmetrical pairs of narrow oval leaflets perpendicular to the leaf stalk, ending with a single in-line leaflet. Over the centuries, thanks to its strength and flexibility, it has been used to make bows, furniture, aircraft and even cars. Much loved, one in every three trees in Britain is an ash. Sadly, Chalara ash dieback is now spreading rapidly across the country and is likely to devastate our wooded landscape over the coming years.
Chalara ash dieback is caused by a fungal infection of Hymenoscyphus fraxineus (formerly known as Chalara fraxinea) that blackens the leaves and causes diamond-shaped lesions in the bark. It has been established across Northern Europe since the early 1990s and first arrived in the UK in 2012; it is thought to have been imported on tree saplings from the continent. Initially, the spread started quite slowly, with the only cases being at sites recently planted with the infected saplings – mainly in East Anglia.
The disease became present within the wider UK tree population of ash trees in 2013/14. Most virulent in young trees, Chalara ash dieback is swiftly working through young plantations and stands of recently coppiced trees, spreading via spores carried by the wind. Motorway, rail and river corridors could be providing uninterrupted links across the country. The disease is now very much present in my geographical area, the North West, and I’m currently engaged with several landowners to deal with the disease in their woodlands.
What will we be losing? The Ash, or Fraxinus excelsior, is a noble native broadleaf tree known for excellent timber properties, particularly used in traditional furniture making, the production of tool handles, bows and sports equipment. It can even be found in British motoring icons such as the Morgan and the Morris Traveller. Charcoal produced from ash coppices fuelled industrial processes – ash woodland is never far away from a lime kiln. Lady Congreves 1930’s poem describes the firewood from Ash to be “fit for a queen with crown of gold” and many an English Estate woodland had an Ash coppice to fuel “the big house”.
Efforts to control the spread of Ash dieback have been largely unsuccessful. One sign of hope is that about 15% of trees appear to remain unaffected and resistant to the disease. The Forestry Commission are not recommending sanitation felling, as they do with other diseases, as this does not prevent the spread, which may come from leaf litter, and also kills the healthy trees that would otherwise survive. Instead the advice is to monitor the spread, fell dangerous trees and plan for the loss of ash by re-structuring woodlands.
A strategy can be prepared within a Woodland Management Plan, for which the Forestry Commission [FC] provides a capital grant, and re-structuring/selective felling/targeted thinning could be supported through the Woodland Improvement Grant. There is support for the worst affected sites through the Woodland and Tree Health Grant, which may include young woodlands planted under any of the previous woodland creation grants where Ash is a major component and the presence of Ash dieback has been confirmed by the FC Woodland Officer for that area. The grant contributes towards replacement trees at fixed rates, up to a maximum payment per hectare depending on the restock species or type.
The prognosis for Ash is bleak and this ubiquitous tree will be widely lamented. Perhaps, however, there is a glimmer of hope, in those trees showing resistance or tolerance to the fungal infection. Identification of individuals which survive exposure may be the key to breeding the ash tree of the future – a process already under active investigation in Lithuania – but this could take decades.
In the meantime, there is an opportunity here to consider other species to fill the void, through a Woodland Management Plan, and this process can be helped on its way with expert advice from ourselves, and the FC.