The Scottish Highlands are celebrated for wide-open views of spectacular glens (valleys) and rugged peaks. After centuries of landscape change, particularly deforestation caused by humans, it is easy to forget how well trees can thrive there. But new discoveries of small trees atop Scottish summits are surpassing the expectations of plant scientists, and demonstrating opportunities for mountain woodland to make a comeback for the benefit of people, wildlife and fighting the climate crisis.
Forest clearance in Britain originally coincided with the introduction of agriculture. Since at least 3,000 years ago, trees and shrubs have been harvested for building materials, firewood and charcoal. Wildfire and controlled burning have also reduced their extent. However, the continuing decline of mountain woodland is mainly linked to overgrazing by domestic hill sheep (introduced in the 18th century) and increased numbers of red deer for sport shooting.
Woody plants, especially willows, are particularly appetising for these animals in the uplands where nutritious food can be harder to find. Overgrazing has caused an almost complete loss of the natural altitudinal treeline – the transition zone from the timberline, where trees grow upright and tall, to the upper boundary where they can establish in the harsh mountain climate.
