It starts with a handful of people in remote woods, looking closely at branches and nuts. In Scotland, about 100 volunteers have helped grow nearly 8 million native trees after collecting 11 million seeds by hand for efforts to restore lost parts of the Atlantic rainforest.

The volunteers, including retired teachers and doctors, office workers and young families, have spent tens of thousands of hours in woods in the western Highlands and islands searching for seed-bearing trees. They have used detailed maps compiled by NatureScot and Scottish Forestry to find pockets of ancient woodland, often in exposed locations, and climbed hillsides to locate the right specimens.

They search for a select group of trees known to have colonised Scotland after the last ice age: hazel, sessile oak, dwarf birch, willow, juniper, birch, wild cherry, wych elm, yew and elder.

Ecologists involved in the project said those trees have inherited the genetic resilience to survive in specific microclimates and soil types along Scotland’s Atlantic coast, an advantage non-native trees would lack as the climate changes.

The latest surveys suggest only 30,000 hectares of original Atlantic rainforest survives. The rare temperate habitat is adapted to the UK’s moist coastal environment.

Those surviving pockets are now the focus of multimillion-pound restoration projects and have been mapped within distinct seed zones devised by forestry experts. Trees for Life has collected, graded and checked the seeds at its nursery at Dundreggan near Inverness, then sent the saplings back to the correct zones.

The Woodland Trust has taken saplings for reforesting projects, including Glenn Shieldaig and Assynt in Wester Ross, and Beò Airceig, a 30,000-hectare restoration around Loch Arkaig in Lochaber. Saplings have also been sold to scores of crofters planting small woods on former grazing land.

Sheena Macauley, a biology graduate who lives near Oban, is one of the volunteers. A former IT manager at Scottish Power’s Cruachan hydro station, she combines seed-hunting with butterfly conservation.

“We need to regenerate for the generations coming behind us,” she said. “I mentioned it to my neighbours and one actually joined up as well. Another friend down in Glasgow, she joined a group down there. So, rather than moaning about climate change, actually do something.”

Her team was supervised by Roz Birch, volunteer coordinator with Trees for Life. Birch uses the outings to give impromptu biology lessons, showing volunteers how to tell Scottish native sessile oak from common, or English, oak by how far the acorns and leaves sit from the twig.

She also points out features of the temperate rainforest ecology, including mosses and lichens growing on tree bark in the moist climate.

“You do have really extreme high winds and storms that will pass through. Again, the trees are pretty well adapted to that environment,” Birch said.

“The uniqueness of the rainforest zone is there will be bryophytes, lichens, whole ecosystems on these trees and within these woodlands, that you can’t really find anywhere else apart from the west coast of Scotland and Wales and the south-west of England,” she said.

The project relies on ecology work and close observation of seasonal weather patterns, drawing on ancient woodland and Caledonian pine inventories. Sites are often surveyed again and Birch said there are clear signs climate heating means seed ripening happens earlier. A dry spring can stress rowan but speed up hawthorn, forcing seed collection dates to shift or be cancelled.

Backers say the work fills a gap left by commercial or state-sponsored forestry organisations because the sites are often too remote or too costly for commercial seed collectors to visit. They believe it is the largest citizen-based reforestation programme of its kind.

The project was originally conceived as a one-year effort and has now received funding for a fourth year from donors including the People’s Postcode Lottery via Woodland Trust Scotland, Trees for Life appeals, the BrITE Foundation and the Clean Planet Foundation.

Another volunteer, Laura Corby, 47, a marine biologist, said she values the focus seed-hunting demands.

“You’re literally growing the future. And that’s a beautiful thing, isn’t it? I don’t think people really understand the significance of the rainforest, even people who’ve lived here their whole lives,” she said.

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