News Release

Legume trees key to supporting tropical forest growth

Peer-Reviewed Publication

University of Sheffield

  • An international team of scientists have explained how legume trees are key in liberating minerals locked in iron minerals and the benefits are passed on to nearby trees
  • The research shows that the trees are able to alter their soils microbiome in a way that increases access to nutrients and supports growth
  • The findings provide new insight into the role of these trees in safeguarding the function of tropical forests and sustainable reforestation

Researchers have found that nitrogen-fixing legume trees can support themselves and surrounding trees not only with increased access to nitrogen, but with other key nutrients through enhanced mineral weathering.

The team, led by the University of Sheffield and the Smithsonian Tropical Research Institute, have published their findings in the journal PNAS which provide new insights into the role of nitrogen-fixing trees in safeguarding the function of tropical forests within the biosphere.

The findings may also help inform practitioners and policy makers on how best to approach reforestation on degraded land and help meet climate change mitigation targets.

The researchers discovered how the nitrogen-fixing legume trees overcome the constraints of growing on ancient, nutrient-poor tropical soils by accelerating weathering processes, releasing vital nutrients for themselves and surrounding trees in the forest.

The trees are able to accelerate mineral weathering processes by locally acidifying the soil and adjusting the carbon to nitrogen ratio of the soil, ultimately changing the microbial community.

This change in soil microbes improves access to nutrients and favours a type of bacteria that breaks down iron, releasing iron-bound minerals critical to tree growth.

Legume trees are also particularly important in the process of forest recovery because they are able to supply fresh nitrogen into soils, which gets broken down by bacteria and utilised by the legume tree and trees around it.

Dr Dimitat Epihov, lead author of the research from the University of Sheffield's Leverhulme Centre for Climate Change Mitigation, said: "Our research shows that legume trees not only provide valuable nitrogen through their symbioses with bacteria that live in their roots, but interact with free-living soil bacteria allowing nutrients to be chemically released.

"We discovered the abundance of a novel group of acid-loving bacteria, key in liberating minerals locked in iron minerals beneath legume trees, and that those benefits are passed on to nearby trees."

Professor David Beerling, Director of the University of Sheffield's Leverhulme Centre for Climate Change Mitigation, said: "By using advanced genomic sequencing techniques we have addressed a long standing puzzle of how fast growing trees access sufficient nutrients to support their growth from nutrient-poor soils.

"The answer, it turns out, is to exploit specialised consortia of soil microbes whose metabolism allows them to efficiently break down rocks and extract nutrients they contain."


The study was carried out in young regrowing forests at the Agua Salud Project in Panama, directed by the Smithsonian Tropical Research Institute.

For further information please contact: Emma Griffiths, Media and PR Assistant, University of Sheffield, 0114 222 1034,

Notes to editors

The University of Sheffield

With almost 29,000 of the brightest students from over 140 countries, learning alongside over 1,200 of the best academics from across the globe, the University of Sheffield is one of the world's leading universities.

A member of the UK's prestigious Russell Group of leading research-led institutions, Sheffield offers world-class teaching and research excellence across a wide range of disciplines.

Unified by the power of discovery and understanding, staff and students at the university are committed to finding new ways to transform the world we live in.

Sheffield is the only university to feature in The Sunday Times 100 Best Not-For-Profit Organisations to Work For 2018 and for the last eight years has been ranked in the top five UK universities for Student Satisfaction by Times Higher Education.

Sheffield has six Nobel Prize winners among former staff and students and its alumni go on to hold positions of great responsibility and influence all over the world, making significant contributions in their chosen fields.

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