The Scots pines that are thought to have largely covered the country thousands of years ago are greatly reduced, but just how big the forest memorialized in Roman texts was is not clear.
Head north from Kinlochewe in Scotland’s northwest Highlands and soon the sleek, mountain-fringed waters of Loch Maree appear. Some 65 uninhabited islands scatter across the loch, itself the fourth biggest in a land of tens of thousands.
Upon the Loch Maree Islands, stands of slender-trunked, broccoli-canopied Scots pines, which in 2014 became the Scottish national tree, reflect in the loch’s still dawn waters, a vision that reflects the romanticism of Scotland. And while the striking red-barked trees are still ubiquitous across the country, they are a fragment of what was once there.
Legend tells of an ancient wildwood of primarily Scots pine that covered much of the land, scaring off invaders and sheltering predators—lynx, wolf, bear—now long gone. Those who know the story of the wood call it by the name the Romans gave Scotland: the Great Wood of Caledon. And while its history is murky and steeped in lore, the wood itself may not have been all that forboding or extensive, experts say.
Scots but not just Scottish
Though intrinsically linked with the story of the “lost” great wood, as a species the Scots pine is remarkably adaptable and opportunistic. Pinus sylvestris is the Scottish tree’s species name, but the Scots pine pops up in plenty of other places around the world.
“From an ecological perspective it’s a pretty spectacular species,” says Tom Ovenden, a forest ecologist and PhD researcher at the University of Stirling. “It has a crazily accomplished distribution.”
He indicates a map that paints a green rash, denoting Scots pine distribution, across much of the Northern Hemisphere—from part of Scotland, to total coverage of Scandinavia, Eastern Europe, and central Russia, to the northern Pacific Coast of the United States. “It is one of the most widely distributed conifers in the world. The ecological and environmental envelope that is encompassed within that range is huge.”
Ovenden describes the tree as an early successional species—“like birch, one of the [trees] that crops up first in a freshly cleared area”—due to light seeds that disperse easily. “They are adapted to grow up fast in relatively high light conditions, and do well in freely draining, quite sandy soils.”
It’s also hardy, and may be able to handle an ever-warming climate better than other trees. “Scots pine is considered to be a relatively drought-resistant species,” says Ovenden. “Older tree bark is thick and fire-adapted, so short, hot, intense fires could sweep through the understory, and the bark insulates the live part of the tree.”
However widely scattered the Scots pine, nowadays Scotland’s principal timber tree is the Sitka spruce. Native to the similarly damp climate of the coastal Northwest of the United States, this exceptionally well-adapted tree was introduced en masse to grow a national timber reserve after World War Two, and now thrives in Scotland, its densely packed regiments starkly at odds with its more flamboyant native counterpart.
Though an ancient species, the Scots pine is not a time machine tree as an individual. Thousand-year-old oaks can be found in England; many sequoias of California’s Giant Forest date from before the time of Christ. A yew still stands in the Scottish village of Fortingall that may be a living link with the Bronze Age. The possible oldest tree of all is a pine—California’s Great Basin Bristlecone, which at 4,800 years old was sprouting around the time Stonehenge was built.
But Scots pine trees have no such longevity, with a typical lifespan of around 250 years and a long one of around 500. What endures, however, is the environment cultivated by its presence.
“Because Scots pine has been here a long time, a lot of other species exist within the habitat it creates,” says Ovenden. “Wood ants, stuff like that.”
Exactly how much of Scotland the ancient forest covered has to largely be guessed, but when clues are found, they can be dramatic. “The best evidence is the remains of tree trunks or roots preserved in peat,” says Richard Tipping, a former University of Stirling professor whose research work focused on Scotland’s environmental archaeology and the changes in vegetation over the ages. “Pine trees grew at times on dry peat surfaces, where they had a competitive advantage over other tree species. As growing peat reduces oxygen and so decay, the bleached ‘bones’ are tangible evidence for where trees once were.”
Few living patches of ancient forest remain. These remnants—38 substantial fragments, 84 if individual stands are included—are classified generally as Caledonian pinewoods. The term isn’t wholly accurate, however, as while some areas of the old forests are dominated by pine, others are dominated by old-growth birch, and along much of the Atlantic coast, oak.
But while the idea of an ancient, contiguous wildwood is a tempting legend, the true story of Scotland’s great forest could be something quite a bit less evocative.
The ‘great wood’ – history or myth?
“I don’t think of the Great Wood of Caledon as a thing of nature at all. I think it was built by the Romans. Or at least, its reputation was.” So says Jim Crumley, a Scottish natural history writer whose book The Great Wood took the legend of Caledon to task.
According to Crumley, the wood was exaggerated by the Romans as a way of explaining to superiors why—upon reaching the northern frontier of their Empire in the Southern Scotland of today—they failed to proceed any further into a land of rough terrain, a furtive climate, and wild tribes that defied suppression. What these nervous would-be conquistadors needed was an excuse even generals back home would accept.
“Word-of-mouth testimony was taken back to Rome by soldiers who found, in Highland Scotland, a realm beyond their comfort zone… but would rather not admit it,” Crumley writes in an email to National Geographic (UK). These whispers “cloaked their retreat in stories of an impenetrable forest. Tacitus wrote it down, and Ptolemy wrote the words ‘Caledonia Silva’ [Scottish forest] on a map.”
But for all the rumours of an impassable forest, it’s likely that by the time any Romans saw it, it was already a shadow of its former extent.
The pinewoods had gradually established themselves in the bare landscapes of Scotland following the last glacial retreat, around 13,000 years ago, a time when little more than moss covered the tundra-like environment. The tree cover was likely to have been at its maximum at around 6,000 years ago – and already considerably chipped away by various agents by the time the Romans clapped eyes on it some 3,000 years after that.
According to Crumley, the forest’s placement on Roman maps was repeated from the 1500s onward. But there are other reasons to doubt the perception of the wood as an impassable thicket: It may have had to have been spread out just to survive.
“The old idea of a dark, dank, dense, and forbidding wildwood has faded, principally because many trees do not set seed in their own shade,” says Richard Tipping. “For regeneration, there must be open spaces.”
Withering of the wood
However you look at it, there’s dramatically less native forest now than there was—around 44,000 acres of pine habitat alone, down from an estimated 370,000 acres at its zenith. As a result, there is less cover for predators, less biodiversity, and less natural order than nature might have specified. “Human beings … created most of the decline. Farming communities need open ground,” says Tipping.
This gradual deforestation of the wood likely began in the Bronze Age, around 4,000 years ago, with trees cut down to open the landscape first for hunting, then grazing. That developed through the Iron Age, then the Middle Ages as the demand for wood steadily grew for ships and buildings, open land for settlements, and fuel for forges.
As the centuries progressed, hunting claimed the last of the forest’s apex predators. Then, beginning in the late 18th Century, the forced eviction of the residents of the Highlands, called the Highland Clearances, saw huge swathes of land used for sheep farming. That destroyed any chances of seedling regeneration and rapidly wiped out younger-growth trees, leaving only what ecologists term the granny pines—older trees.
Logging of the pines fuelled the Industrial Revolution, when timbers supplied the shipbuilding in Glasgow and Edinburgh.
The trees lined the Allied trenches of the First World War. The Second World War galvanized Britain’s desire for a self-sufficient source of timber, and so the Sitka spruce was introduced from North America. Its rapid growth lead to widespread clearing for plantations— reaching a height in the 1960s and 1970s—ploughing up the old forest and pressuring many native species, including red squirrel, capercaillie, pine marten, now part of conservation programs.
Others, such as the Scottish wildcat, hang by a thread. The boar and the beaver, the brown bear, Eurasian lynx and wolf, were wiped off the native map long ago. And plants like the luminous, delicate twinflower, (Linnea borealis) a relic of the ice age, now only exist in a handful of pinewood fragments.
-National Geographic