Scotland’s rainforest: What is it, where is it and why is it under threat?

Invasive species, climate change and grazing are among the threats facing Scotland's rainforests.
Invasive species, climate change and grazing are among the threats facing Scotland's rainforests.
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When you think of a rainforest you probably imagine lush ferns under towering trees knitted together by a maze of dense vines, the air damp from steam heat, all of it filled with bizarre insects and tropical birds.

Whatever your idea of a rainforest, it probably doesn’t encompass a sodden moss-covered habitat on Scotland’s West Coast, being grazed upon by deer and devastated by invasive flowers.

Ballachuan Hazelwood reserve is one of Scotland's rainforest areas

Ballachuan Hazelwood reserve is one of Scotland's rainforest areas

It might be a well-kept secret, but Scotland’s rainforests do exist - and as well as being rarer than their tropical counterparts, they are also facing a more uncertain future.

Here’s everything you need to know.

What is Scotland's rainforest made up of?

Scotland’s rainforest is far more than just trees.

Also known as Atlantic woodland or the Celtic rainforest, it's a unique habitat of ancient and native woodlands, open glades, boulders, crags, ravines and river gorges, garlanded with rare lichens, mosses, liverworts, fungi and other plants – some found nowhere else in the world.

It is a temperate rainforest, rather than a tropical one, and as such, it's extremely rare. The conditions required for these to thrive - high annual rainfall, very little variation in temperature and clean air - occur in less than 1 per cent of the planet’s surface.

Temperate rainforests used to occur more widely along the Atlantic coastline of Europe, but now they are only found in small areas.

Like their tropical counterparts however the temperate rainforest is home to a huge abundance of wildlife found nowhere else on earth, and it's one of the world’s rarest habitats.

Scotland’s rainforest woodland is diverse, with 60 different species of trees and shrubs, and a variety of micro-habitats that can support rainforest wildlife.

The most important, and most delicate of these, are the lichens, with species such as Octopus Suckers, Black-eyed Susan and Smokey Joe thriving.

Mosses and liverworts are ancient non-flowering plants which have been around for 400 million years.

Where is Scotland's rainforest?

The rainforest areas can be found along the west Coast of Scotland.

Crinan Wood in Argyll, Ballachuan Hazelwood on Seil Island, Balmacara Estate in Kyle of Lochalsh and Lochaber's Allt Mhuic include areas of the ancient and bio-diverse woodland.

In total there are estimated to be 30,325 hectares (almost 75,000 acres) of native woodland which contains rainforest biodiversity.

That is just 21 per cent of the area where conditions are right for rainforest plants.

The remaining 63,000 hectares of woodland on the West Coast is, however, a potential site for rainforest plants, and calls have been made to provide protection for these areas.

Why is the rainforest under threat?

The constant pace of change and the expansion of human activity is putting a huge strain on the natural world across the globe, so it’s hardly surprising that one of the most fragile, and rarest habitats on earth should be in crisis.

Even so, the problems facing this unique habitat are already worryingly diverse, with the forest being lost to overgrazing by deer and livestock, invasive plant species and disease.

Already much has been lost, and what is left is fragmented, broken and often isolated in a wider landscape.

There are 125 Sites of Special Scientific Interest (SSSI’s) within the rainforest zone along the west coast of Scotland.

Of the rainforest areas within these, almost half are in unfavourable condition.

Grazing is by far the biggest direct threat, with more than 12,000 hectares of rainforest facing a level of grazing that will impact its long-term survival, diversity and regeneration.

The biggest threat are dear, with livestock responsible for just 20 per cent of overgrazing.

Climate change is another major issue for the rainforest, with lichens and bryophytes highly sensitive to atmospheric pollution.

Diseases such as ash dieback are threatening the trees upon which much of the rainforest relies. Development pressures are also impacting the edges of the sites.

And perhaps the most bizarre, and yet most serious threat comes from the invasive rhododendron.

A popular flower, it is already widespread throughout the rainforest, and poses a threat because it can colonise rainforest woodland and out-compete native trees and plants.

What can be done to save the rainforest?

The problems facing Scotland’s rainforest have been highlighted by the Atlantic Woodland Alliance, a group of 16 charities and organisations which has been identifying the threats facing this unique habitat and devising a way to save it.

The alliance includes Forestry and Land Scotland, Loch Lomond and Trossachs National Park Authority, National Trust for Scotland, Plantlife Scotland and the Royal Botanic Garden Edinburgh.

They have proposed eradicating exotic species of plants, such as Sitka spruce and Rhododendron ponticum, from thousands of acres of rainforest, and planting more native trees, such as oak and birch.

There needs to be urgent action to improve the management of the rainforest zone, to limit grazing and remove invasive rhododendron, while planting protective strips of forest around the most fragile areas of rainforest and giving them the best chance to flourish.

Gordon Gray Stephens of the Community Woodlands Association, said at the unveiling of a report into their proposals to save the rainforest: "Our vision for regenerating Scotland's rainforest is clear. We need to make it larger, in better condition, and with improved connections between people and woods.

"Coming together as an alliance can help to make this happen."