Endangered mountain trees making a comeback in Scotland, study shows

Overgrazing by deer and sheep on Scotland’s peaks since the 18th century contributed to a rapid decline in high-altitude woodland, so much so that by the 1990s native montane willows were nearly extinct, with the largest remaining patch equivalent to 'the size of a tennis court'.

Since then, almost 400,000 montane willows have been planted within 2,659 hectares managed for the restoration of mountain woodlands across Scotland, bringing the trees back from the brink of extinction.

The area these special arctic-alpine plants occupy has 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.

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A review of progress made over the last 30 years has been carried out by PhD researcher Sarah Watts, of the University of Stirling’s Faculty of Natural Sciences.

Ms Watts 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.

“Mountain woodland also stabilises steep slopes and gives protection from the natural hazards of avalanches, rockfalls and landslides. It slows the flow of water over and within upland soils, facilitating a decrease in flooding downstream. These benefits are called nature-based solutions because they are considered vitally important for reducing threats from escalating climate change including more extreme weather.”

Sarah Watts at Mar Lodge Estate (Image: Sarah Watts/University of Stirling)

Montane willow scrub is one of six habitats the National Trust for Scotland has prioritised in its Plan for Nature, announced earlier this year. In it, the conservation charity, which cares for 76,000 hectares of countryside in Scotland from coastlines and islands to mountains, makes it clear where it plans to focus its efforts to help nature flourish.

Jeff Waddell, Head of Nature Conservation at the National Trust for Scotland, added: “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.”

Ms Watts is hopeful that there will be an expansion of restoration on land managed for other purposes. She said: “As well as focusing on conservation areas, future action should harness the capacity for nature recovery on land previously managed intensively for sport shooting, which often host natural populations of montane willows in need of rescue and enhancement.

“Through the progression of wider collaboration fostering habitat connectivity, montane scrub restoration should help deliver a sustainable future by reducing impacts of nature and climate emergencies on a national scale. Treeline reestablishment must be underpinned by management for low-density large herbivore populations to remove the pressure of overgrazing and enable a balance between sustainable numbers of animals and plant growth.

“This vision would require moving beyond relatively small-scale projects held behind fences toward action at landscape scales. Enhancing rural employment and retaining invaluable skills in deer management will be fundamental for meeting this goal.”