They were once a regular sight in the Scottish Highlands, offering a home to wildlife such as golden eagles, ring ouzel and the mountain hare.

However, centuries of over-grazing by sheep and deer mean the landscape has been stripped of what was once one of its most common features - wee trees.

Most of the once-ubiquitous, tough, waist-high trees such as dwarf birch and downy willow - known as 'montane' species because they grow in some of the world's harshest conditions, near Scotland's mountain summits - are gone.

But the woody perennials could soon be making a comeback thanks to plans by a conservation charity to create what will be Scotland's largest planted area of rare high-altitude woodland.

The charity, Trees for Life, founded by Scots ecologist and natural history photographer Alan Watson Featherstone, is making a major bid to reverse the loss of these unique woodlands.

The organisation is establishing a 700-acre mountaintop woodland of 100,000 trees at its Dundreggan Conservation Estate in Glenmoriston near Loch Ness.

The site - Carn na Caorach, meaning 'sheep cairn' - lies at 450-600 metres above sea level on Dundreggan's northeastern edge, with sweeping views over Glenmoriston and Glen Affric. It is thought to have been an important place for grazing livestock for hundreds of years.

Dundreggan Conservation Estate manager Doug Gilbert, said: "Montane woodlands are a vital part of Scotland's precious Caledonian Forest, but are often restored over only small areas if at all. 

"To bring these special 'wee trees' back from the brink, and create habitats for the wildlife that depends on them, we need something bigger - and that's what we're setting out to achieve at Carn na Caorach."

The charity has already erected its largest-ever exclosure at the site - a fence designed to protect young trees by keeping grazing animals out - and volunteers will begin the first phase of planting in the spring, with trees including downy willow and dwarf birch on the higher ground, and Scots pine and juniper on the lower slopes. 

Further planting will continue over the next few years, and self-seeded saplings will also be able to thrive in the grazing-free exclosure.

It is expected that the initiative will also see the return of plants including wood cranesbill, globeflower and alpine sowthistle, in turn supporting mammals, birds, and pollinating insects such as bees and butterflies.

The new forest will benefit people, helping to tackle climate change by locking away carbon dioxide, and reducing flooding by improving the soil's capacity to retain water.

It will take 50 to 100 years before the forest is fully established, because such high woodlands take longer to establish than those in sheltered locations. 

The ambitious project follows Trees for Life's successful planting this year of 10,000 trees at another area of Dundreggan called Beinn Bhan, which lies at over 500 metres above sea level.

Seed from montane trees - for growing saplings in Trees for Life's specialised tree nursery at Dundreggan - often needs to be collected from precipitous mountain ledges and crags, sometimes by qualified climbers.

Trees for Life is dedicated to rewilding the Scottish Highlands, and its volunteers have established nearly two million native trees at 44 sites, to benefit wildlife, people and communities. 

For more information or to support the charity's fundraising appeal to help create the Carn na Caorach woodland, see www.treesforlife.org.uk/appeal.