RETURN OF THE ELM
By the late 1980s, almost all mature specimens of the once-iconic elm tree had died in the UK as a result of Dutch elm disease. Mark Rowe investigates attempts to reintroduce elms to Britain
As a child, walking underneath an elm tree was like swimming under water,’ recalls Robert Somerville. ‘An elm is a vast cavernous space, very cool, the branches drooping down.’ Thanks to the ravages of Dutch elm disease, this is a vanishingly rare experience today. Around 25 million elms, accounting for 90 per cent of all elm trees in the UK, died during the 1960s and ’70s of the disease. In the aftermath, the elm, once so dominant in our landscape, was largely forgotten, slipping from the collective memory.
‘I grew up in Elmstone in Kent – the clue’s in the name,’ laughs Somerville. ‘The village had a huge elm; every village, every green had a huge elm on it. If you were travelling by train, out of the window you’d see an elm 20 feet taller than anything around it. They were giants, awe-inspiring.’ A master woodworker who builds barns from elm and strives to revive traditional crafts, Somerville believes that, 100 years after the disease was first named – in 1921 by Dutch scientists – there’s now hope that the elm may be reintroduced to the countryside of central and southern England.
Any reintroduction or planting will start from a very low base. ‘The impact of the disease is difficult to picture if you hadn’t seen what was there before,’ says Matt Elliot, policy advocate for tree health and disease/ invasives at the Woodland Trust. ‘You look at old photographs from the 1960s and it’s only then that you realise the impact. Elms were on field edges, they were a massive component of hedgerows, they were significant, large trees, open-grown in fields. You had huge elms in pasture for cows and sheep – then they were gone.’
The disease emerged after the First World War as a mysterious malady and initially took out 10–40 per cent of Britain’s elm trees. It’s caused by a fungus that blocks the elms’ vascular (water, nutrient and food transport) system, causing branches to wilt and die. The first epidemic died down and by the 1960s, the disease was sporadic. That changed in the ’70s with a second epidemic, triggered by shipments of rock elm from Canada. The wood came in the form of logs destined for boat building and its intact bark was perfect for the elm bark beetles that spread the deadly fungus. This time, the beetles carried a much more virulent strain that took out 90 per cent of elms. Were that not enough, the abrupt transition to a more intensive form of agriculture and the grubbing up of hedgerows amounted to what Elliot calls ‘a double whammy. Once you grub them up, that’s the end of it’.
Now endemic, the disease is spreading slowly north, although its impact on the predominantly wych elm populations of Scotland and northwest England (where climatic conditions are less favourable to the beetle) is, to date, less devastating. A strong population of elms can be found in Edinburgh and the city’s botanic gardens.
Elm is still widespread in the southern English countryside but mostly only in hedgerows. ‘We have millions of small elms in hedgerows but they get targeted by the beetle as soon as they reach a certain size,’ says Karen Russell, a chartered forester and co-author of ‘Where We are with Elm’, a report for the Future Trees Trust (FTT). Once the trunk of the elm reaches 10–15 centimetres or so in diameter, at about eight to 15 years of age, it becomes a perfect size for beetles to lay eggs and for the fungus to take hold. Yet mature specimens have been identified, in counties such as Hertfordshire and Cambridgeshire, that are hundreds of years old, and have mysteriously escaped the epidemic. And a new generation of elm seedlings that appear to be resistant to the disease is being bred. Ideally, elite disease-resistant elms could be crossed with local elms for planting in parks, towns and the countryside.
The FTT now believes that British elms could be brought back into more common existence and is encouraged by a new generation of elm seedlings that
were bred by the late Dr David Herling of the Resistant Elms organisation, which appear to be disease-resistant. ‘Elm is relatively easy to propagate; it grows from cuttings, from seed,’ says Russell. ‘But a whole generation of people have pretty much written off elm. We need to make people aware of its potential for planting.’
The key, she says, is to identify and study those trees that have survived (such individuals largely belong to the field and wych elm species) and work out why they stood tall when millions of others succumbed. These survivors could then be crossed with other resistant varieties. Nevertheless, opportunities are limited as the number of these mature survivors is relatively small – Somerville puts it at around 1,000.
‘What are the reasons for their survival?’ asks Russell. ‘Avoidance, tolerance, resistance? We don’t know where the balance lies between the three. I don’t see how it can be entirely down to luck. There have been many substantial waves of disease; the pathogen and the beetle are well established in the wider environment. It would usually be a very rare occurrence for a mature tree to survive a disease such as this. Before, it was like looking for a needle in a haystack, but if there are only 1,000, the haystack is much smaller.’
For hundreds of years, elm ran oak a close second as the hardwood tree of choice in Britain and was in many instances the most prominent tree in the landscape. Not only was elm common in European forests, it can be a key component of birch, ash and hazel woodlands. The use of elm is thought to go back to the Bronze Age, when it was used for tools and dwellings. Elm was also the preferred material for shields and early swords. In the
Around 25 million elms, accounting for 90 per cent of all elms in the UK, died during the 1960s and 1970s in the UK
18th century, it was planted more widely as an amenity tree and its wood was used for boxes, crates, bedroom flooring, toilet seats and bicycle rims. Its alkaline nature made it popular for dough trays and the tree was an important fodder crop, with the leaves favoured by livestock. The keel of the Cutty Sark came from elm and other uses include mining equipment and ammunition boxes: ‘Anything that needed to resist an impact,’ says Somerville. ‘Elm is great for building, it has a lot of cross grains, incredible swirling grains, it won’t split and it’s beautiful to look at.’ The last use, for which it’s perhaps best remembered, is as wood for coffins, which perhaps explains why for some, who associated it with morbidity, its disappearance was unlamented.
Given how ingrained elm is in British culture, it’s unsurprising that the tree has many advocates and that the yearning to reintroduce the elm is so strong. As Russell delved deeper into her research, she became aware of a network of ‘elmies’, enthusiastic individuals – farmers, engineers, lawyers – who’ve independently kept the flame of the elm alive and have been quietly crossbreeding or nurturing surviving elms. ‘They’re often
committed amateurs who have put in decades of effort,’ says Russell. ‘Many of them grew up in the 1960s and 1970s and saw the destruction, the widespread felling of elm in their childhood, and it really stayed with them. But they weren’t pulling together,’ she says, ‘because they didn’t know others were out there – no-one has really been collectively banging the drum for elm.’
Passion and fascination are certainly features recognised by Peter Bourne of the National Elm Collection in Brighton, who freely admits that he has the elm bug. ‘I saw Dutch elm disease unfold as a small boy,’ he says. ‘The elm seemed to be part of rural England, but I remember watching trees just lose their leaves and that really stayed with me.’ Brighton’s elms were planted by well-to-do Victorian and Edwardian families, and total about 17,000 (some 40 feet high, although most are less than three feet in diameter). Brighton has 125 varieties, 20 of them endangered, including the Scampston elm, thought to be the last example of its type. The red seeds of the weeping Scampston, says Bourne, resemble ‘droplets of blood falling from the canopy’.
Local factors appear to have contributed to the Brighton elms’ survival. Strong winds from the sea and the shelter of the Downs to the north and east make it difficult for the determined elm bark beetle to make incursions. The main risk of exposure is from the west, where winds can blow beetles and the fungus across the Adur river valley, which means local elms are lost every year. ‘The beetles can just march in if we’re not careful, so the threat is right on our doorstep,’ says Bourne. ‘The main risk is actually logs. People buy them from nearby and bring them into the city.’
Across England, the reality is that the elm bark beetle is now triumphant, so any prospect of the return of elm relies heavily on trees being either resistant to, or tolerant of, the disease. This means a widespread reintroduction would involve existing or new hybrid strains derived from resistant, generally non-native elm species. The seedlings bred by David Herling have been tested to see if they can withstand the fungus by cutting a small slit on the bark and injecting an inoculum of the pathogen. ‘The effects are very quick,’ says Russell. ‘You return in four to six weeks and trees that are resistant show no symptoms, whereas those that are susceptible show leaf loss and may even have died completely.’
All of this raises questions of social acceptance, acknowledges Russell. ‘If we’re putting elm back into the landscape, a small element of it is not native – are we bothered about that?’ For her, it doesn’t seem a big problem. ‘To the untrained eye, a hybrid looks the same as native elm.’ The environmental case for reintroducing elm is strong, too, she argues. ‘They will host wildlife, which is a good thing. We need diversity in species. They are good for the caterpillar of the white-letter hairstreak butterfly and for wild bees.’ Many birds and some small mammals eat elm seeds and the leaves provide food for the caterpillars of many moths, including the peppered, light emerald and white-spotted pinion moths.
Others are more wary. ‘On the face of it, it seems like a good idea – just find the disease-resistant elms and all will be fine,’ says Elliot of the Woodland Trust.
The problem, he suggests, is that the replacements are ‘essentially horticultural plants – they’re not from nature but elaborate crosses from China, Siberia. You’re replacing a native species with a horticultural analogue. You’re effectively cloning.’ Elliot is also unsure about the longterm resilience of such trees. ‘It’s a risky path. You don’t want to introduce any new diseases.’
Rather than plant new elms, the Woodland Trust emphasises providing space to those elms that have survived independently. ‘There’s no guarantee, but sometimes the best thing you can do is just give nature time to recover,’ says Elliot. ‘Natural regeneration is really the key. It gives you long-term resilience. A lot of genetic mixing goes on in the hedgerows and eventually, over time, you might get resistance.’
The reintroduction of elm is incredibly ambitious, acknowledges Somerville. Yet he believes the daunting nature of the challenge is no reason not to try. ‘It’s a pipe dream, but I think we should still do it, even if only for future generations. It’s going to be 200 years before the landscape sees the change, even if we plant a hybrid today. Planting trees for a future we won’t necessarily see seems rather noble. [The hybrids] may not be native, but elm fits so well; it has co-evolved with our landscape,’ he adds. ‘We live in a managed landscape – if we chose not to interfere, then that landscape and its flora and fauna changes. We just end up with scrub.’
The case for elm’s return is becoming more pressing, given the spread of ash dieback as well as pest threats to oak and sweet chestnut. ‘If we lose the big four or five tree species in our landscape, what’s left?’ asks Somerville. ‘That spectacle is pretty grim. Not interfering means we may well end up with a landscape with no tall trees, which would be terrible.’
Perhaps the strongest case for returning elm to the wider landscape is the tree’s sheer stature. ‘Elm was everywhere – you saw it in hedgerows, in avenues, in urban areas,’ says Russell. ‘Their grace, stature. They are just such beautiful trees.’