The walking trees

It doesn’t feel quite right to call this giant lime a ‘tree’; it is a thicket, a tangle, perhaps even a mess. I push through the dripping crown, now strewn across the woodland floor, and explore the complex geography within. Five enormous stems radiate from their former perch on a little rocky knoll over a tumbling beck. One has broken a few metres up, twisting open to reveal great braids of wood like unwound rope. The downhill trunk has snapped clean off and sprung clear, sliding to a stop amongst the oaks beneath. The others have fallen from the base and torn the thin layer of moss and soil away from the rock as they peeled into their new, prone positions. The roots on the lower side of each are intact so the crowns are still thriving, lush with the delicate heartshaped leaves of small-leaved lime.

As I perch amongst the jumble of limbs there is a sense of dynamism and change that is uncommon in ancient woods: a gap rent in the canopy, bright limewood brought into view through torn bark, leaves and twigs set at the wrong angle. The energy and thrill of the new creeps up on me past my initial shock and sadness on finding the final two stems collapsed. This is a tree I have known for some time.

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The limes in Dodgson Wood, on the shore of Coniston Water, are famous – if that’s the right word – amongst tree nerds. They were studied and recorded by the global authority on lime, Professor Donald Pigott, and they demonstrate beautifully, in a few dozen trees, the recent history of the species more widely. Here, they are restricted almost entirely to the ‘ghylls’, the steep-sided, fast flowing streams that channel water from the boggy fell above to the lake below. They were probably grubbed from the rest of the wood a few hundred years ago when woodland management – integral to human existence since the Bronze Age –became even more industrialised and the tree species of most use and economic value were encouraged to the exclusion of others. This is the home of Arthur Ransome’s charcoal burners and the wood is dotted with pitsteads – levelled charcoal hearths –and the stone foundations of bark-peelers’ huts: oak was big business here and, like in most woods along Britain’s Atlantic coast, it was promoted almost exclusively.

Small-leaved lime, in contrast, became redundant. Its main product had been its fibrous bast, the living wood just beneath the bark, that could be twisted into string and then plaited on into rope, clothing and other fabrics. The arrival of hemp and jute from parts of the world new to Europeans meant that lime was no longer welcome in woods being managed for things people needed – that is to say, almost all of them. In Dodgson, we think it was simply too much trouble to remove the lime on the crags and steep slopes over the ghylls, so the trees were left to do their own thing.

The arrival of hemp and jute from parts of the world new to Europeans meant that lime was no longer welcome in woods being managed for things people needed – that is to say, almost all of them.

The population here demonstrates why the species has continued, in most places, to be restricted to the edges and forgotten places – but also why it has managed to cling on. Pollen records show that small-leaved lime (along with its close relation, large-leaved lime) dominated the canopy across much of England before people started to modify the landscape. The species hasn’t naturally returned to the woods from which it was cleared because the climate cooled and the lime-seeds didn’t get the warmth they need to develop properly (until recently, of which more later). Lime has an evolutionary trick up its sleeve, however: it is highly adapted for vegetative reproduction. When old lime stems break, the trees produce masses of new coppice-growth from the stumps. When they fall from ground level, keeping the roots and crown alive, the side branches can shoot skyward to become a row of trees while new roots sprout into the soil from the underside of the stem. The sweeping lower branches can even take root where they touch the soil, sparking close companions to standing trees.

This knack for survival has seen the last few wild populations of lime hang on despite their inability to reproduce sexually, persevering in their quiet corners as they fail, and grow: and fail again, and grow again, potentially in perpetuity. Some people call them ‘the walking trees’ and it is an extraordinary glimpse into deep-time to consider their perambulations up and down the impenetrable ghylls of Dodgson Wood. You can often read the last couple of iterations into the form of the trees you find. This middle-aged tree here can be traced, via the decaying old branch there, to that giant old veteran nearby. A row of younger trees is suspiciously straight and uniform and, upon scuffing the earth between them, we find the last spongy remnants of the fallen trunk from which they all sprang. Perhaps most pleasing is the pair connected by a sweeping limb across the beck, a living bridge. Each of these trees – although it is all but impossible to say where each individual begins and ends – is among the oldest living things in Britain. The climate cooled relatively quickly after trees recolonised our landscape when the ice receded, so each wild specimen of small-leaved lime may be a good few thousand years old, but has regenerated and transformed countless times along the way.

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The National Trust looks after more ancient and veteran trees than any other landowner in the UK (and, by extension, probably the world, due to Britain’s unique population of old trees). The ancient trees of our imagination are almost invariably the old oaks, beeches and yews of our parklands and fields: the fat, gnarled oaks of Croft Castle or Calke Abbey, the giant overstood beech pollards of Ashridge, the Anckerwycke yew and Borrowdale’s fraternal four. Each tells a powerful tale of the human history it has both witnessed and been shaped by, and forms an ecosystem in itself of wood decay, fungi and rare invertebrates, not to mention birds, bats and mammals.

I love the oaks – and the beeches and yews –and yet I am always drawn back to our native limes. While ancient oaks seem to represent solidity and permanence, their age enabled by the durability of their wood, lime speaks to me of something more fluid and subtle, a triumph of adaptation rather than resistance. The excitement of exploring out-of-the-way spots and forgotten edges for wild lime is also undeniable and many of the National Trust woods where the species remains reflect that history of being pushed to the edge then clinging on through their amazing ability to regenerate.

Pollen records show that small-leaved lime (along with its close relation, large-leaved lime) dominated the canopy across much of England before people started to modify the landscape.

In Leigh Woods, overlooking Bristol from above the Avon Gorge, lines and groves of lime define the woodbanks lost among the oak and hazel, helping to reveal the geography of the old coppice-coupes. At Blickling in Norfolk giant sprawling limes again illuminate almost-imperceptible lost boundaries, and a straight line of ancient wild limes was even supplemented with planted common lime to create an eighteenth-century avenue. (Common lime is, as you would expect, the lime we come across most often. It’s a nursery hybrid of small-leaved and large-leaved lime that was planted widely in designed landscapes and parklands, as well as being a popular street tree in the Victorian era.)

I feel sure there is something more to the story of small-leaved lime and boundaries. While in some places – like Dodgson Wood, or the ravine woods of the White Peak – the species was pushed back to the places where it simply couldn’t be removed, there’s no physical reason why our ancestors who worked these woods couldn’t remove lime from the woodbanks: there must have been some other reason to leave it there. Perhaps there was some specific local demand for its fibre; perhaps this is where the beehives were kept, to take advantage of lime’s abundant flowers – it is thought that lime was often retained for this reason in other parts of Europe. Perhaps, however, there was a less prosaic meaning attached to lime that we have, in Britain, lost, even in the past couple of hundred years. In many parts of northern Europe lime is held in particularly high esteem for its beauty and as a symbol of love, fertility and wellbeing. Individual trees are revered as historic meeting places and they may have represented peace between neighbours.

This potential loss of the deeper meaning that lime held for our ancestors reflects our very recent disconnection from woods and their management and with the natural world more broadly. It is only since the second world war that British woods have ceased to form an essential component of our industry and economy; the people managing them even between the wars would have presumably been able to tell us why the seemingly ‘useless’ wild limes were retained.

Perhaps the immortality of lime was, in itself, important, as the great age of yews is thought to have made them attractive as places of Pagan worship. There is some evidence to suggest that sacred groves in Iron Age Germany were of lime. Whatever meaning our predecessors found in the species, today I find a powerful sense of perspective that helps me consider our response to the crisis in climate and nature. That response is central to the National Trust’s strategy: we recognise that through the management of our 250,000ha of England, Wales and Northern Ireland we have the potential to store and sequester vast quantities of carbon and to restore and create vital habitats for wildlife.

Some of this is a new type of work for us, but like the wild lime regenerating to survive, the Trust has continually evolved throughout its 127-year history to deliver the changing needs of society. In terms of trees and woods, we’re gearing up to deliver even more great woodland management, improving the condition of our woods for the species they support and ensuring they’re inspirational places to visit. We’ve also committed to establishing 20m new trees by 2030, improving the resilience of farmland in both environmental and economic terms as well as sequestering carbon and making space for nature. To get this right for nature and for people we need to respect the deep history of our places while also thinking about the long-term future: the continual and changing pressures that our places may be subject to and which will require lime-like responsiveness and adaptation.

Small-leaved lime will also play a part in our plans to create thousands of hectares of new wooded habitat. It is a beautiful native tree that is only under-represented in our current treescape because it declined in use for people; it is great for wildlife and will thrive in a warming climate. While climate change is too severe a threat to meaningfully talk of silver linings, one effect so far is that lime saplings are no longer absent from British woods and can be readily found across the south-east; our warmer summers mean the seeds can now develop to viability.

I am down in the ghyll among the ferns, splashing through the shallow summer flow and staring up between the great fallen stems spreading from the crag above. The broken base of the lime is already obscured by a bush of vibrant new growth, its future assured. But I want to know if this tree will walk. I have been visiting this tree for at least a decade and, to my surprise, I have watched it collapse in stages from the spectacular specimen I first met to this wild tangle beneath an open sky.

This potential loss of the deeper meaning that lime held for our ancestors reflects our very recent disconnection with woods and their management, and with the natural world more broadly.

On the bank opposite the crag, the pitstead is obscured by the crown of the great arcing stem that used to frame it like a stage. Although the branches are still alive thanks to the continued connection to the roots, none of them have settled into the earth and ‘layered’ to form new trees; the slightest ongoing movement will stop new roots forming. When I first stumbled into this changed scene it was a blow, felt as the loss of a friend. Over time I’ve come to recognise that I’m simply observing small-leaved lime’s fundamental nature and have come to appreciate the opportunity to witness its transformation in real time. I’ve also learned that it’s the instinctive reaction of the lime enthusiast to look for new growth from fallen stems and low branches when they find an old lime like this, to try to find evidence of the miraculous process of regeneration that has seen these trees persist since pre-history.

Finally, perhaps eight years after that first failure, I find it: a little grove of wrist-thick saplings striving for the light from the dry bed in the depths of the ghyll. The branch from which they’ve developed has been buried by sediment brought down by winter floods, locking it in place and enabling fine new roots to creep into the earth. The lime has taken another step, extending its toehold a few metres up the ghyll. It occurs to me that this scene has been repeating itself here since trees reclaimed these fells after the last Ice Age, and I experience a giddying sense of my irrelevant place in this tree’s deep-time story. Standing in its presence connects me to the decisions that the previous custodians of these woods have taken throughout human history - and beyond, to before the influence of people, when aurochs might have browsed the tender leaves and bears laid up in its shade. It extends the other way, too: wild limes like these will probably outlast us all and could continue to thrive here in any of the futures open to humanity. The perspective that we take from them can help us redefine our relationship with the planet and contribute to decisions that take those possible futures, and their inhabitants, into account; it should give us confidence in the actions we need to take now to be good ancestors to those who will inherit our legacy.

Luke Barley is the National Trust’s senior adviser on trees and woodland. This article, like any reference to lime, is indebted to the work of Professor Donald Pigott (both his monograph Lime-trees and Basswoods and his generosity in sharing his knowledge). Luke would also like to credit Roman Krznaric’s The Good Ancestor and The Long Time Academy podcast for helping him understand and articulate the intuitive feeling evoked in the presence of wild lime.