Ashes to ashes: How a foreign fungus is killing off Britain's ash trees
Throughout Kent and East Anglia, the elegant, luxuriant deep green of late summer ash woodland has been reduced to a threadbare tangle of branches and twigs – the victim of ash dieback. Nick Johannsen explains how even urgent action may not be enough to save this stately beast
As a child growing up in East Anglia, two mighty elm trees were anchors in my world. Even more feral than my own children, wherever we wandered above the Dedham Vale, two gigantic elm trees signalled home. Without warning these beautiful twins were quickly and ruthlessly cut down by Dutch elm disease. Our welcoming elms became giant, gloomy monoliths, quickly felled, logged and stacked.
Dutch elm disease was good for the chainsaw and log stove market. Across Britain there ensued the removal of dead and dying elms on a drastic scale, which created a dramatic diminishment of much loved landscapes. In my own East Anglian clay land, the change was appalling, lanes which were once tunnels of cathedral-like elm trees became scrappy hedges; field trees felled and not replaced, woods completely altered, the landscapes changed forever. When my father died nearly 40 years later he had not finished burning the logs he cut and stacked even from our tiny farm.
And now for ash, perhaps our most graceful tree, the die seems cast. Ash dieback was first recorded in Britain in 2012, although there is speculation that it was here years before. Also known as Hymenoscyphus fraxineus, is a fungal pathogen and a most serious disease of ash trees. It is stealthier than Dutch elm; the death of ash trees is slower: there are moments of apparent recovery, but the eventual decline seems irrecoverable. The estimates are that between 95 per cent and 98 per cent of our ash trees are threatened; this would seem to be borne out by what we are witnessing in some of the ash dominated woodlands in east Kent.
So great is the threat that common ash (Fraxinus excelsior), the everyday tree of our streets, hedges and woodlands, is now listed on the International Union for Conservation of Nature (IUCN) Red List. Ash dieback was first identified in Europe in Poland, in 1992, where it is believed that it arrived on commercially imported ash from East Asia. In its native Asia, the fungus will have co-evolved with the Asian species of ash, on which it therefore has limited impact; European ash has far less immunity. The fungus lives in the leaf litter and has a delicate if peculiar beauty. Thousands of airborne spores are released and can disperse naturally on the wind over tens of kilometres. Continual cycles of infection and reinfection from the leaf litter below produce trees punch drunk with pathogen.
Ash dieback is well described: the effect of the fungus is to block the water transport systems in trees causing leaf loss, lesions in the wood and on the bark, and ultimately the dieback of the crown of the tree. Young trees succumb quickly; in older trees the decline can take between six to 20 years. When the fight is lost, the weakened tree succumbs or is attacked and ultimately killed by another pest or pathogen. The elegant, luxuriant deep green of a late summer venerable ash is reduced to a threadbare tangle of branches and twigs. Desperate new “epicormic” growth emerging from the trunk and branches changes the form and elegance of the tree, once more diminishing our landscapes.
An ash tree is a whole ecology: almost 1,000 species use ash as a habitat, including wood mice, liverworts, wrens, blue tits, bats, lichens, fungi and beetles. Bullfinches will eat ash keys in winter when food is scarce. The caterpillars of many kinds of moth feed on ash leaves. Many lichens are hosted by ash. Lichens are not a parasite and they do not feed off the tree, but use it as a support. According to Oliver Rackham, author of the brilliant book The Ash Tree, the ash is the last refuge of many declining tree lichens, especially those that once grew on elms before they fell victim to loss of habitat through Dutch elm disease. King Alfred’s Cakes (Daldinia concentrica) are specific to ash, and a number of beetles that live only on this fungus are dependent solely on ash for survival.
It is true to say that some ash trees appear to be able to resist or tolerate infection. There is a significant scientific effort going into studying the genetic factors which make this possible so that tolerant ash trees can be bred for the future. Interesting and exciting developments in the science are occurring all of the time and the Living Ash Project reports big steps in collecting, grafting and growing from trees that are identified as being “putatively tolerant to ash dieback”.
Despite the extent of devastation already witnessed elsewhere in Europe and in certain parts of Britain, scientists from the Earlham Institute have found an incredibly limited genetic diversity in the fungus. It would seem that the original infection in European ash may have come from just one or two mushroom-like fruiting bodies. According to the Natural History Museum the diversity of the fungus found across Europe is just an eighth of that found in a single Japanese woodland, so is likely to be a just a tiny fraction of that found across Asia. Imagine what might happen if more of that Asian genetic diversity is brought into Europe.
The ash dieback story is bleak, but for the beleaguered ash tree another perhaps even more serious threat approaches from another invasive species with its own surprising beauty. The Emerald Ash Borer beetle, again a native of Asia, was imported accidentally to North America, thought to have been on something as apparently innocent as wooden packing material. The impact in North America has been widespread and devastating, killing hundreds of millions of trees since the 1990s. Emerald Ash Borer has now been found in Russia and is moving westwards and southwards at a rate of around 25 miles a year.
The extreme vulnerability of our trees to imported pests and diseases is most dramatically illustrated by the loss of elm and ash. Our trees have such long lives; our treescapes take such a long time to recover from these attacks that managing the risk of importing further diseases and pests must be a critical issue for the future. There are a wide variety of other tree diseases, which are known threats: while many websites have listings of the top things to do, see or visit, rather sadly the Forestry Commission website has a list of “top tree diseases”.
Ash dieback is just one of a list of 14 top diseases, and the borer beetle one of the eight top pests. The loss of a single beautiful tree can be felt deeply and personally; we face the loss of hundreds of millions of trees from Britain’s treescapes, the forces for change are enormous and the response should be in equal measure.
Earlier this year the government produced a 25-year plan for the environment, an ambitious initiative that has signalled a strong intent to leave the environment in a better state than it was found. The “at a glance” summary includes the need to protect our many plants, trees and wildlife species in its very first line. One of the first, most tangible early outputs of the plan is the Tree Health Resilience Strategy. The strategy sets out an integrated approach, which seeks to significantly strengthen biosecurity in procurement and practice, deploy the best science and evidence to understand and respond to the risks in an informed way and to increase the extent, connectivity, diversity and condition of our trees and woodlands.
The strategy recognises that there is a real need to increase the resistance of our treescapes so that there is no further substantial change or loss, and to support the recovery and adaptation of our landscapes in what will inevitably be a most difficult future.
There is a scientific, technical and conservation response to ash dieback and it is vital that there is, but what is the cultural response? What about the little boy who lost his elm trees and is now working to try to conserve and enhance the Kent Downs, one of Britain’s finest and most ash dominated landscapes; what is the emotional response?
Ash facts
Think you know the tree of life?
A fully grown ash can reach a height of 35 metres and can live to 400 years or more. The trees can be easily recognised by their black buds and clusters of seeds – which can be a menace for gardeners proud of their lawns. Native to Europe, Africa and Asia, ash is dominant in many parts of the UK and provides the perfect habitat for various wildflowers on the woodland floor, as well as numerous bird species which nest in its branches. In days gone by the ash was believed to have healing properties – in Viking mythology it was known as the ‘tree of life’.
The hills and valleys of this enchanting quarter of Kent are punctuated by ash, our most common tree. Ash is intrinsic to the place, it is in the names of the villages, towns and woodlands; one of the most affected woods has two names, Asholt Wood and Ashley Wood; a single remarkable ash tree is marked on the Ordnance Survey map for Ashford.
We expect that we will lose almost all of our ash trees and so we feel that it is vital that we record and celebrate what we have before it might be lost. We want to do this in extraordinary and enduring ways so that we connect more with our trees and treescapes and provide a record for the future. For elm, Gerald Wilkinson wrote Epitaph for The Elm. Hastily put together and almost too late to record fine elm trees in the landscape, it is a saddening record. Our idea is to salute the tree, as well as mark the loss.
The Ash Project, which is funded by the Heritage Lottery Fund and the Arts Council of England, combines a major new sculptural commission by internationally recognised artists Ackroyd & Harvey with a wide-ranging programme of walks, talks and exhibitions. We have created a temporary archive that records both the extraordinary utility of ash and celebrates ordinary ash objects that we all might know.
The Ash Archive involves existing objects and art works and new commissions across a range of art forms, and the public is invited to add to a growing, collectively generated collection. Our approach has been to collaborate across conservation and scientific research work to develop new languages with this massive environmental change. It is our hope that, through the Ash Project, we will preserve our memories of the tree for the generations who will live with the loss.
The cultural celebration is also supported by a collaboration with the Woodland Trust and a number of Areas of Outstanding Natural Beauty, in which ash is dominant, to work with author Archie Miles to publish a monograph. Titled Ash, this new publication pays tribute to the ash tree in all of its glorious manifestations across the landscapes of the UK. The book, on sale now, is a loving homage to the ash tree.
On a practical basis we are working with a wide variety of organisations to support a Kent-wide plan for landscape restoration. We have produced guidance for landowners in order to plan wide scale recovery and to ensure we retain much of the biodiversity that ash supports, but surely more must be done across the country to prevent further landscape and environmental loss.
As the summer wanes the impact of ash dieback is at its greatest. At this time of year in Kent we see the ink-like blackening of the leaves of affected trees, with leaf fall occurring as much as a month or two earlier than it should, bringing the bleakness of winter to the landscape all too soon.
It is in this season that we have chosen to present Ash to Ash – a monumental art work by Ackroyd & Harvey. Standing high on the scarp of the Kent Downs, two giant monoliths stand proud, almost defiant. One the bright white of newly cut ash wood, the other charred and blackened like the inky leaves of an affected tree. These extraordinary pieces, made from ash dieback stricken trees, are pierced by more than 10,000 arrows, handmade from coppiced ash. They act as marker trees, on the edge of the North Downs Way.
Overlooking a landscape already damaged by ash dieback, they will be a striking reminder of all that we stand to lose. Unlike the giant elm monoliths of my childhood, this extraordinary artwork both memorialises and celebrates the ash.
In Kent and East Anglia the impact of ash dieback is already, in places, devastating. This seems likely to be the story across the country over the next 10 to 15 years.
Ash is perhaps most closely associated with some of our most valued landscapes, the Areas of Outstanding Natural Beauty and National Parks. Places such as the Cotswolds, Chilterns, High Weald, Lake District, Dorset, Yorkshire Dales, White Peak and Snowdonia are, in part, defined by their relationship with the ash tree, there is a great need to document and celebrate these landscapes also.
We plan to take the work we have started in Kent to a national platform, to collaborate across Britain with landscape managers, artists, scientists and ecologists to ensure we mark and honour the graceful Venus of the woods, the tree of life, before it is lost to us.
Nick Johannsen is director of the Kent Downs Area of Outstanding Natural Beauty Unit. The Ash Project was conceived and is managed by the unit. To find out and hear more about the Ash Project please go to theashproject.org.uk.
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