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Six million trees counted from a small plane: the Cairngorms is regrowing itself

Qurexa Editorial Team24 September 20266 min read 0 0
Six million trees counted from a small plane: the Cairngorms is regrowing itself

What happened

For centuries, most of Scotland's native woodland has been missing. Trees were cleared for timber, for grazing and for farmland, and where seedlings did try to come up, deer ate them. Planting trees behind fences has been the usual answer. A survey published on 24 September 2026 suggests something different has started to happen in the Cairngorms. The forest is coming back by itself. A team led by the University of Cambridge flew a light aircraft at about 600 metres over 569 square kilometres of the Cairngorms National Park. The aircraft carried LiDAR, a laser scanner that fires pulses of light at the ground and measures how long each one takes to bounce back. Do that millions of times and you get a three-dimensional map precise enough to measure individual trees. The team then used a new AI-assisted method to pick out trees from the point cloud. They counted more than six million individual trees, and measured the height of every one. Of those, 2.65 million - just over 40% - were under five metres tall. In other words, young. More than 5,235 hectares of land that used to be open ground now supports young woodland, defined as more than 100 trees per hectare. The work came from Cambridge's Centre for Landscape Regeneration, funded by the Natural Environment Research Council and the Endangered Landscapes and Seascapes Programme, working with Cairngorms Connect and RSPB Scotland.

Why this matters

The number that matters most is the 40%. A wood full of old trees is a wood that is slowly dying. A wood where four in ten trees are young is a wood with a future. What makes this different from a planting scheme is that nobody planted these trees. They arrived on their own, from seed, spreading out from existing woodland into ground that has been bare for centuries. The reason is deer management. Cairngorms Connect is a partnership working across around 60,000 hectares, which is unusually large for Britain, and it has taken a landscape-scale approach to reducing deer numbers rather than fencing off small patches. Fewer deer means seedlings survive long enough to become trees. That is a cheaper and more durable way to get woodland than planting. Naturally regenerated woods tend to have a better mix of species, better-adapted genetics and a more natural structure than planted rows. It also matters for how we measure conservation. Until now, a lot of restoration reporting has relied on how many trees were planted. Planting is an input. This survey measures an outcome: how many trees are actually standing, and how tall they are. Those are not the same thing, and the gap between them has embarrassed more than one tree-planting target.

What the evidence actually says

Be clear about what has been shown. This is a measurement, not an experiment. The survey counted trees at one point in time across one area. It shows that young woodland is now present over thousands of hectares that used to be open. It cannot prove on its own that deer management caused it, because there was no comparison landscape scanned in the same way. That said, the explanation is well supported by decades of separate evidence. Deer browsing is the single biggest barrier to natural woodland regeneration in Scotland, and that has been demonstrated repeatedly in fenced-plot experiments. There is also a timing point. These trees are young. Under five metres means, for Scots pine in the Highlands, somewhere around 10 to 25 years old depending on conditions. They are not safe yet. Deer pressure can return, and a bad run of dry summers or a disease outbreak could change the picture. The method has limits too. LiDAR is very good at finding trees above a certain size and less reliable with very small seedlings under heather. So the true number of young trees may be higher than counted. What the survey genuinely provides is a baseline. Fly the same route in ten years and you will know, with real numbers rather than impressions, whether it worked.

Practical advice

If you want to see this for yourself, the Cairngorms National Park is open to visitors all year and the regenerating areas around Abernethy, Glenfeshie and Insh Marshes are reachable on foot. A few things are worth knowing before you go. Stick to the Scottish Outdoor Access Code, keep dogs under close control near ground-nesting birds and deer, and be aware that stalking seasons affect some estates in autumn. If you want to help woodland regeneration closer to home, planting is not always the answer. In many places the more useful thing is protecting what is already trying to grow: leaving scrub alone, resisting the urge to tidy field edges, and letting hedges get taller and thicker. If you are involved in a community group looking at land, ask about natural regeneration before ordering saplings. It is usually cheaper, and the survival rates are often better. And if you follow environmental news, this is a useful example of the difference between a target and a result. When you see a tree-planting pledge, the question worth asking is not how many were planted but how many are still alive five years later.

What to know

Aerial laser scanning across 569 square kilometres of the Cairngorms counted more than six million trees. Over 2.65 million of them, just over 40%, are under five metres tall, and more than 5,235 hectares of formerly open ground now carries young woodland. Nobody planted these trees. They spread naturally, following a landscape-scale approach to deer management across the 60,000-hectare Cairngorms Connect partnership area. It is a snapshot rather than a controlled experiment, and young trees are not yet secure trees. But it is a properly measured baseline, and it suggests that in the right conditions the cheapest way to grow a forest is to let it grow. Sources: University of Cambridge, 'Successful woodland expansion in Scotland's Cairngorms revealed in aerial maps', 24 September 2026, https://www.cam.ac.uk/research/news/successful-woodland-expansion-in-scotlands-cairngorms-revealed-in-aerial-maps ; Phys.org, 'Aerial maps reveal successful woodland expansion in Scotland's Cairngorms', 24 September 2026, https://phys.org/news/2026-09-aerial-reveal-successful-woodland-expansion.html ; Cairngorms Connect, 'Woodland Expansion in the Presence of Deer', https://cairngormsconnect.org.uk/news/109/37/Woodland-Expansion-in-the-Presence-of-Deer This article is for general information and does not replace advice from a doctor, pharmacist or other qualified healthcare professional.

#Cairngorms#rewilding#woodland#Scotland#LiDAR#conservation

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