Dr Euan Bowditch, a researcher at the Scottish School of Forestry at Inverness College UHI, considers the plight of the elm and highlights efforts to conserve, manage and restore populations of this iconic tree.
The elm. A tree synonymous with the Dutch elm disease and spoken about as if it has already faded into memory. Poor Dutch, forever tethered to one of the worse tree disease outbreaks in modern history and to this day remains a cautionary and sad tale for all that work with or appreciate trees.
As it happens, the Dutch are not the cause of elm disease – or even the origin – but were the first to identify the causal agent of Dutch elm disease in the 1920s, as several phytopathologists (those who study plant disease) pinpointed the fungus Graphium ulmi (Ophiostoma ulmi). A few miles further east of the Netherlands in the Himalayas, we find the origin of the disease, which travelled across the vast continental distances to Europe, all the while hybridising and adapting to new conditions and species.
Today, Dutch elm disease continues to travel, spreading into the heart of the Scottish Highlands and reaching more isolated populations nearly seventy years after the break out in the 1960s. In my experience, Dutch elm disease is often perceived as an absolute; an unrelenting disease that has vanquished the species and now remains dormant or waiting. The elm bark beetle (Scolytus scolytus), which carries the fungus, is dynamic and continues to hop across the landscape, driving deeper into remote areas of the Highlands. Equally, the elm tree is not a dormant or dead species, but alive; regenerating and even adapting in ways which are as of yet unknown.
Although wych elm (Ulmus glabra) is on the International Union for Conservation of Nature Red List (the only tree species in Europe to be on the list), the species is widely spread, but in smaller numbers and fragmented. Healthy trees and populations persist and survive, maybe the focus on elm and Dutch elm disease has been overshadowed by the advent of such diseases as ash dieback, needle blight and sudden oak death (Phytopthora ramorum), which has devastated plantations of larch all over Scotland. Trees are under constant threat; not just to disease, but events of extreme weather such as storms and drought that will weaken the tree and, in conjunction with disease, are capable of knocking swathes of forests down like dominoes across landscapes on a continental scale.
Almost a century on from the identification of the disease, we are still learning, experimenting and looking for better ways forward to conserve, manage and restore elm populations. Yesterday, ‘The Last Ent of Affric’, a mature surviving elm tree in the famous Glen has been named Scotland’s Tree of the Year. Hidden away in a remote spot, it has avoided Dutch elm disease and is a sole survivor of the ancient woodland in which elm would have been a key species.
So, revival is happening culturally perhaps; but what about ecologically, genetically and even economically? Elm is a beautiful decorative wood, with diverse uses; valued for its strength and water resistance, and once used for ship-building. Now, most elm is used for furniture, with burr wood especially prized.
Currently, the Wooded Landscapes Research Group at Inverness College UHI is undertaking work in partnership with the Woodland Trust to set-up pilot refuges for healthy elm populations and running a scoping study on DNA extraction techniques on healthy and Dutch elm disease infected elms, with the aim to identify resistant traits by comparing differentiation of DNA markers. Our hope is to gain some insights into potential resistance of elm and propose ways of restoring the lost populations, which would in turn restore rare native woodland habitats and the associated species.
Trees are so deeply embedded with our culture and folklore that we can take them for granted. According to Norse mythology, for example, Elba was the first woman created – from the wood of an elm tree – by the gods. Next time you are wondering around a wooded area, road verge, fields or any green area, try and spot an elm; the ancestors of the Ents will be watching.
Dr Euan Bowditch
Forestry and social-ecology researcher
The Scottish School of Forestry
Inverness College UHI