Clinging to cliff faces and rocky outcrops are the gnarled and stunted high-altitude survivors of times long gone by.

Shaped by the elements and in defiance of deer, sheep and mountain hares who would happily gobble up their green shoots if they could reach them, Scotland’s montane woodland birch trees are found few and far between and often in the hardest to reach spots.

It is in stark contrast to southwest Norway, an area of similar climate, geology, topography, habitats and species. There, at the same altitude and similar climate as the Highlands, woodlands thrive across vast swathes of mountain landscapes, skiers whizz down tree-lined slopes and every citizen has access to a woodland hut.

Now Scotland’s climbers and mountain adventurers are being asked to help regenerate the barren high-altitude areas they love, by supporting efforts to create the kind of lush landscape found in southwest Norway.

A call has gone out to rock climbers and hill walkers to look out for and to share details of birch and other trees growing above 650m, often sprouting from craggy cliffs and in random spots well off the beaten track.

It’s hoped that by identifying trees at precise locations, plant experts can retrieve their seeds, store them and nurture them into seedlings which can be planted at high altitude sites in the future.

According to Dr Duncan Halley, of the Norwegian Institute of Nature Research, the process would help kickstart natural regeneration of lost higher-level woodland habitats, boosting biodiversity and increasing carbon storage.

The regeneration could transform Scotland’s desolate higher level landscape from treeless and bare – just as Norway’s southwest area was less than a century ago – into lush woodlands attracting birds like the mealy redpoll, a migrating bird of which just 300 are thought to visit the UK every year, and bluethroats, a small robin-like bird with a delightful song which, because of lack of habitat, is currently a rare visitor.

Both species thrive in southwest Norway’s regenerated woodlands.

According to Dr Halley, who left Scotland 28 years ago to live in southwest Norway, there are remarkable similarities between the two locations, making the Norwegian regeneration success a template for what could be achieved here.

“The current situation in Scotland is the cumulative result of millennia of land use practices,” he says. “Today it is maintained and reinforced - many existing native woods are not regenerating and so will eventually die off if present conditions persist - primarily by grazing pressures exerted by high densities of deer and sheep; and muirburn.

“At higher levels, above about 600m, woodland is more or less extinct in Scotland when it should, in the central Highlands, reach in some form to about 900m.

“This is reversible, as clearly indicated by developments in southwest Norway.”

There, overgrazing had left hillsides bereft of montane scrub, with mountain areas shown in old photographs as being remarkably similar to Scotland’s highlands.

“What happened in Norway was by accident,” he adds. “For various social and economic reasons, grazing pressure fell off.

“Around 100 years ago, there was mass emigration from Norway as people went to the United States of America where they could receive a quarter of a square mile of land for free.

“As a result, around one third of the population of Norway left, and the amount of grazing fell.”

Areas which had come under pressure from sheep and cattle began to regenerate naturally. Although the Great Depression sparked a return to farming which had an impact on the landscape, in post-war Norway new jobs were created which, again, led to a decline in grazing.

That helped sparked a natural regeneration of woodland areas, with previously bare slopes now rich in various species of trees, shrubs and wildlife.

He adds: “I have been watching this happen for 28 years in Norway. It starts slowly but once the process begins, it gets faster and faster.

“You have one little tree that starts to seed. Once it gets going it’s really fast, I describe it as snowballing. Pretty soon you have a bunch of trees.”

Photographs taken of locations in Norway show the extent of regeneration over the course of 100 years. In Fidjadalen valley, an area said to be extremely similar to Glen Nevis, the reduction in sheep grazing and deer has created a verdant landscape of mixed native trees and shrubs.

In Oslibakken, near Stavanger, one image from 1911 shows a bare landscape which, by 2015, had been transformed with slopes covered by a variety of trees. While in Fonnes, Hordaland, bare rocks and He said one particularly striking comparison is between southwest Norwegian ski slopes at the same altitude and with similar properties to Cairngorm. There skiers enjoy woodland runs in winter, and hikers follow forest trails in summer.

Dr Halley said the change in landscape has altered how Norwegians use the land: its thriving hut culture provides every citizen with the opportunity to spend time in a woodland hut, while hunting – a major sport in Norway – forestry and other land uses have adapted.

“You can imagine the top of the Drumochter Pass, which is not a particularly attractive landscape, with semi-natural forest. It would be a good place for a lot of cabins with good road and rail access can blend into the landscape,” he added.

“In Norway, servicing these places is a significant part of the rural economy. “Most men and a minority of women hunt, but the way hunting is done has changed. Instead of grouse moors, grouse live in this mixed, busy open areas towards the top end of the woodland. Hunting is done by walking up and shooting, instead of driven grouse.

“If someone is looking for enormous bags of grouse, they would have a problem, but if looking to go grouse hunting, where a large bag is not your motivation, then it’s fine.”

Because Scotland’s handful of high-altitude birch and tree species have adapted to their locations, their seeds are a particularly vital component in enabling successful regeneration.

“Any trees that are left will generally be small and confined to cliffs where deer and sheep cannot reach them – often only visible at close range to people like climbers.

“We are asking rock climbers who might find these very small trees to safely record what they see.

“We can then build up some idea of where these trees are, so we can arrange for the seeds to be harvested.”

He adds: “It was very often maintained in Scotland that the treelessness of the Highlands was natural or irreversible, but southwest Norway has shown that’s not the case.”