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We need to talk about nitrogen -
air pollution's impact on nature

Excessive nitrogen in the atmosphere is one of the greatest threats to our wildlife and habitats, yet few people have even heard about it. Air quality plans and new farming policy post-Brexit are key opportunities for the next UK government to tackle this forgotten issue.

April 2017

What’s the problem?

Global emissions of nitrogen oxides (NOx) from fossil fuel burning (in transport, power stations and industry) and ammonia (NH3) emissions (mainly from farm animals and fertilisers) have more than doubled since 1960, leading to a build-up of reactive nitrogen. NOx and NH3 emissions are harmful both to human health and to the health of our natural environment. Yet air pollution’s impacts on biodiversity are not factored into the assessment and management of protected wildlife sites, land management policies or even air quality plans.

How does air pollution affect wildlife?

Rare species are increasingly confined to road verges, farmland margins and protected areas but, even there, they cannot escape the devastating impacts of air pollution.

Deposited directly from the air and rain, nitrogen enriches and acidifies the soil, and causes direct damage to wild flora and fungi. Effects include bleaching, leaf discolouration and poor resistance to drought, frost and disease.

Lichens are well-known as indicators of air quality and many species are highly sensitive to nitrogen pollutants. Close to nitrogen sources, lichens such as the Eyelashes treebeard (Usnea florida) may be bleached and overgrown with algae.

Over two thirds of our wild flowers – plants like harebell (Campanula rotundifolia) and betony (Betonica officinalis) - require low or medium levels of nitrogen. Only robust species, such as nettle (Urtica dioica) and hemlock (Conium maculatum) thrive in nutrient-enriched soils. These gain a competitive advantage, leading to a loss of overall diversity. Early evidence suggests negative knock-on effects for insects, birds and other species.

How widespread is this problem?

Woodlands, grasslands, heaths and bogs have all become colonised by nitrogen-loving plants. In 2014, 90% of land in Special Areas of Conservation (SACs) in England and Wales received excessive levels of nitrogen deposition; for the UK as a whole it was 63%.

Plantlife and Plant Link’s report We need to talk about Nitrogen highlights current scientific evidence in this area, produced in collaboration with Link partners RSPB, the National Trust and the Woodland Trust, and with the Centre for Ecology and Hydrology, the Stockholm Environment Institute and other partners.

What can be done?

We need to talk about nitrogen with government, industry, farmers and the public, alongside more familiar environmental issues, such as climate change, water pollution and habitat loss. It deserves to be part of our mainstream environmental thinking and taken up by all those working in the environmental, air quality and farming sectors.

At a political level, more concerted commitment, investment and coordination across local, national and international levels are needed to tackle this issue effectively.

What’s the good news?

There are plenty of opportunities to achieve this – once we get it on the agenda. It is a cross-cutting issue, best tackled through strategies on food and farming, transport, industry, energy, climate change, air and water quality, green infrastructure and public health.

Air quality strategies have gained a high public profile in recent years – and rightly so. This provides a critical opportunity to tackle air pollution’s impacts on wildlife.

From a farmer’s perspective, simple steps – such as covering slurry stores and spreading fertilisers more efficient - can make a huge difference.

More broadly, new land management and farming policy for the UK outside the EU is an opportunity to reduce nitrogen emissions, prevent their dispersal, mitigate the impacts and restore our wildlife and habitats.

Jenny Hawley

Senior Policy Officer, Plantlife

Find Jenny on Twitter @JennyHPlantlife

To find out more, see the report of Plantlife’s January 2017 workshop, held with British Ecological Society’s Plants-Soils-Ecosystems SIG and a range of stakeholders to identify the challenges and solutions, in policy and practice.

The opinions expressed in this blog are the author’s and not necessarily those of the wider Link membership.