Air pollution ‘wreaking havoc’ on Scotland’s rare species and habitats, damning report warns

‘Intolerable’ levels of nitrogen spell disaster for some of the world’s most precious habitats, including Scotland’s temperate rainforests, writes Harry Cockburn

Scotland’s rainforest is home to rare lichens, funghi and ferns (Getty)

Air pollution from traffic, power stations, farming and industry is “silently wreaking havoc” on some of Scotland’s most globally important species and natural habitats, a new report warns.

Nitrogen levels have now become “intolerable” in areas, including its rare temperate rainforests, its peatlands and species-rich grasslands, threatening the country’s unique blend of biodiversity.

Even the country’s mountaintops have nitrogen levels “higher than they can tolerate”, according to a damning report for the Scottish government by Plantlife Scotland.

The report warns in just under half of wood habitats, and a quarter of open habitats within Scotland’s Important Plant Areas have exceeded their critical load – the point at which nitrogen harms habitats.

This is causing a rapid decrease in plant, lichen and fungi diversity, the researchers said.

The report, backed by WWF Scotland, the Soil Association, the Woodland Trust and others, reveals more than a third of all Scotland’s nitrogen-sensitive habitats and 80 per cent of its land within Special Areas of Conservation such as the Cairngorms, have intolerable nitrogen levels.

Excess nitrogen pollutants in the air, which the authors of the report attributed to road transport, power stations, farming and industry, are being deposited into the environment, directly damaging the fragile ecology.

The report said nitrogen exposure on already fragile habitats is leading to a loss of species, lower resilience to the worsening climate crisis, and increased vulnerability to pests and disease.

Across Scotland’s rare rainforests, as well as in mountains, grasslands and other woodlands, the unnaturally nutrient-rich and acidic soils are being colonised by common and fast-growing “thuggish plants” such as nettles and hemlock, which outcompete Scotland’s ancient, rare and endangered wild plants, lichen and fungi.

Alistair Whyte, head of Plantlife Scotland said: “The effects of air pollution on health are well documented with industry traditionally the key culprit. But nitrogen deposition is also rapidly devastating our iconic habitats and the impacts of this invisible enemy are still not being recognised with sufficient urgency.

“Alarmingly, we are now finding that habitats perceived to be furthest away from the source of air pollution such as the unique rainforests of the west coast, are on the borderline of reaching their nitrogen thresholds from far-reaching emissions.”

The report said nitrogen oxide emissions, mainly from transport and energy generation, have declined but are still a significant source of pollution affecting Scotland’s wildlife.

Meanwhile, Scotland’s ammonia emissions, 92 per cent of which come from agriculture, have only declined by 16 per cent since 1970 and are “unlikely to improve without rapid, targeted action and collaboration”.

Mr Whyte added: “It is not too late to halt this. There are huge opportunities for conservationists, agriculture and Scottish government to work together to implement the recommendations in our report.

“Our environment and our farmers will benefit from a clear strategic vision for the future of agriculture in Scotland, and from properly targeted support measures to help tackle this problem.”

David Michie, associate director of farming and land at the Soil Association Scotland, said: “Nitrogen is essential for life on earth, and vital for food and farming. But when used in excess nitrogen becomes a damaging pollutant threatening climate, nature and human health.”

Scotland’s temperate rainforest is a particularly rare habitat worldwide. These mainly coastal forests have a special “oceanic” climate, which is very wet, but also mild, due to the landscape and warm ocean currents.

This unlikely combination in Scotland, together with high levels of rainfall mean the woodlands are very humid, creating the conditions for the growth of globally significant species of lichen, mosses and liverworts, fungi and ferns. It is regarded as one of the most important rainforest sites in Europe.

Just 30,000 hectares of rainforest remain in the country according to the Woodland Trust, and the last remnants are already under threat from overgrazing by deer and sheep, the impacts of the climate crisis, invasive species such as rhododendrons, and diseases such as ash dieback.

The Independent has contacted the Scottish Environmental Protection Agency for comment.