Learning from plants

Composite of Professor Carly Stevens (centre) between images of the agricultural landscapes she works in

Plants tell us a huge amount about the environment they grow in, says the new Lancaster professor who specialises in how air pollution impacts on biodiversity.

Growing up in a rural area, Professor Carly Stevens got a first-class education in the local wildlife, starting her fascination with plants and what they reveal about the world around us. 

‘By the time I finished infants I knew the names of all the local birds, butterflies and flowers though I couldn’t read or write well,’ says Carly, who has just been promoted to a Chair in plant ecology and soil biogeochemistry at the Lancaster Environment Centre, where she has worked for 8 years.

‘What still fascinates me about plants is that they tell you all sorts of things about soils, climate and the wider environment: you see this through their traits, how they are responding to different pressures and by the different species you find in an area.’

Carly is best known for her work charting the rise in atmospheric nitrogen and its impact on plants and the wider ecosystem.

Atmospheric nitrogen is produced mainly from the burning of fossil fuels and from the animal waste and artificial fertilisers involved in intensive agriculture. The nitrogen gets into the atmosphere and then enters the soil through rain, dust and gasses. It acts as a fertiliser, discouraging many native plants, which flourish in low nutrient conditions.

While creating major environmental problems, atmospheric nitrogen has never received the same attention from the public or scientific community as carbon dioxide emissions.

‘We can all get on board with too much CO2 being damaging,’ says Carly, ‘but nitrogen is more complicated. Crops need nitrogen and we actively put it on them, but in other places it’s a bad thing.'

After studying Ecology and Environmental Science at undergraduate and masters’ level, Carly did a PhD at the Open University, looking at the impact of atmospheric nitrogen on plant communities around the UK. Carly spent two years travelling the country, taking and analysing soil samples and recording the plant communities in 68 different field sites.

‘My research showed that in areas of high atmospheric nitrogen deposition we get lower numbers of plants. It was the first time anyone had shown conclusive evidence of the impacts of nitrogen deposition in the natural environment. It had been shown in experiments, my research showed it was actually happening and that it was damaging biodiversity.’

Carly’s paper on the research was published in Science, one of the world’s top scientific journals – an almost unheard-of achievement for a first paper by a young researcher. Science thought the paper so significant, that they arranged a press conference in the Royal Institution and asked Carly to present her research.

'It was terrifying, a roomful of journalists from the major newspapers and media. It cured me of nerves for giving talks because nothing would be as terrifying again.'

Carly ended up on the front page of the Guardian and in many other newspapers and media outlets. Her paper has been widely cited since.

A year later, Carly joined Lancaster University to work on soil erosion, and how to reduce phosphorus and sediment pollution in agriculture, but she found she was missing plants. An EU grant, giving her the chance to expand her UK atmospheric nitrogen experiment to different sorts of grassland right across Europe, took her back to the Open University. The European study confirmed her UK results, and fed into EU and UK policy.

‘Nitrogen pollution limits are set by critical loads: the evidence we gathered helped to set the critical load to a lower level and fed into approaches to habitat protection,’ explains Carly.

She was awarded a Leverhulme Early Career Fellowship, to study how grasslands recover from nitrogen deposition, and how this interacts with climate change.

‘Leverhulme Fellowships are great because they give you so much freedom to explore your ideas. I was able to work closely with UK policy makers looking at the impacts of nitrogen on different habitat types and helping them with developing indexes, providing evidence for critical loads.’

She also got involved with the Nutrient Network Collaboration – a global collaboration where scientists all run same experiment across the world.

'A lot of the experiments were tackling really fundamental questions in plant ecology: about how plants compete with each other, how plant communities interact with climate change and other big global change problems like invasive species.'

‘It connected me with some high-profile ecologists across the world, all interested in grasslands, and led to some amazing collaborations and papers in high profile journals like Nature and Science.’

Carly returned to Lancaster as a lecturer – ‘probably helped by having a paper in Science published on the day of the interview’ - and now, becoming a professor.

Nitrogen has remained at the centre of much of her work. She is currently leading the evidence review to revise the critical loads for grassland habitats.

She helped to create two Massive Open Online Courses (MOOCs), on Food Security and on Soils and is the academic director of the Waitrose Collaborative Training Partnership, a £2 million training and research programme. More than 30 PhD researchers are working with Waitrose producers and suppliers on projects to improve sustainability in crop production, soil and water use, biodiversity and ecosystem services in agriculture.

‘It’s an absolutely amazing project, the opportunity it opens up for PhD researchers to work directly with food suppliers throughout their PhD and see their work put into action. It’s given me a much better understanding of how food systems work.’ Carly is also director of the Lancaster Environment Centre’s postgraduate research programmes, covering almost 200 PhD and masters level researchers. She loves supervising students and helping them to achieve their research ambitions.

Four years ago, Carly had her daughter, Keira, and is now juggling her demanding work with being a mother. Before having a child, she worried about how it would impact on her career. She now feels very supported by her departmental colleagues and that being made a Professor shows that female academics with young families can still progress within the university.

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