Endangered mountain trees make comeback after pioneering project in Highlands beauty spot

Montane willows were at risk of disappearing altogether, with overgrazing by deer and sheep on the country’s peaks since the 18th century contributing to their decline.

But the resilient species has now joined other mountain trees and shrubs in making a comeback in Scotland’s landscape, according to new research.

Montane scrub, a form of high-altitude tree-line woodland, helps mitigate the effects of extreme weather, researchers have said. The habitat provides protection from flooding, avalanches, rockfalls and landslides, as well as supporting a range of rare insects and scarce birds.

The area these special arctic-alpine plants occupy has now increased a hundredfold since the 1990s thanks to the efforts of conservation charities and private estates working on a long-term vision for nature recovery, a new study by the University of Stirling has shown.

Almost half a million (400,000) montane willows alone have been planted within 2,659 hectares managed for the restoration of mountain woodlands across Scotland in that time.

A review of progress made over the last 30 years has been carried out by PhD researcher Sarah Watts, at the University of Stirling.

Ms Watts, who has climbed some 200 Munros in her research, said: “There is significant capacity for a high-altitude vegetation type that was nearly nationally extinct to make a comeback and flourish under conservation management.

“Reviving a mountain woodland mosaic shaped by regeneration will tackle biodiversity loss and help mitigate climate change impacts on a national scale.

“Montane scrub supports a vibrant community of insects including bumblebees, butterflies, moths, and over 20 rare sawfly species in Scotland that each rely on an individual species of arctic-alpine willow for their survival.

“The habitat also hosts upland birds that are scarce or declining elsewhere in Britain, such as the Ring Ouzel, a charismatic mountain blackbird.”

Ms Watts’ latest paper Montane willow scrub restoration in Scotland: reviewing 30 years of progress to reestablish the altitudinal treeline was published on Tuesday in Restoration Ecology, the journal of the Society for Ecological Restoration.

The review looks at best practice across Scotland, and features some of the environmental organisations that took part in the planting including RSPB, Borders Forest Trust, Trees for Life, Corrour, Forestry and Land Scotland, and particularly the work led by the National Trust for Scotland (NTS).

Montane willow scrub is one of six habitats the NTS, which cares for 76,000 hectares of countryside in Scotland from coastlines and islands to mountains, has prioritised in its Plan for Nature, announced earlier this year.

Ms Watts said the pioneering site for montane willow restoration in Scotland is Ben Lawers National Nature Reserve, owned and managed by the NTS.

“No other restoration project in the country is comparable in scale and longevity,” she said.

“Here, widespread planting of 54,882 montane willows took place during 1998-2012.

“Over 110 hectares of montane scrub has now been restored at Ben Lawers, accompanied by an explosion of invertebrates, mammals, and birdlife. This site is undoubtedly the most biodiverse place in Scotland’s mountains.“

She said Mar Lodge Estate, also owned and managed by the NTS, has demonstrated “outstandingly successful application of supplementary planting together with landscape-scale deer management; 5,797 montane willows planted here in 2021 and 2022 had a 100% survival rate during recent monitoring.”

Jeff Waddell, head of nature conservation at the NTS, said: “Montane willow scrub is one of our rarest habitats, with only a few hundred hectares remaining throughout Scotland. It supports a range of rare and scarce species, and it is one of the habitats where our work can make the biggest impact.

“As Sarah highlights in her research, we have spent many years carrying out pioneering work to regenerate and restore this habitat at both Ben Lawers National Nature Reserve and Mar Lodge Estate National Nature Reserve. Nature needs to be protected now more than ever and our success so far in restoring montane willow scrub demonstrates what is possible when habitats or species are prioritised and given the opportunity to thrive.

”Sarah is hopeful that there will be an expansion of restoration on land managed for other purposes.”