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Conserving genetic diversity of ash trees

Scientists have developed a new approach to conserving genetic diversity, using European ash – a species in severe decline – as a case study.

Around the world, forest trees are increasingly at risk from habitat destruction, pests and disease, and changing climate. Conservation scientists are working to develop guidelines for conservation actions that are effective at saving species but also efficient, in terms of using our limited resources. However, there are currently limited guidelines for effective preservation of a species’ genetic diversity and adaptive potential. 

To help solve this problem, Dr. Sean Hoban at The Morton Arboretum in collaboration with scientists from Kew’s Millennium Seed Bank, have developed a novel approach to designing ex situ collections that effectively preserve a target species’ genetic diversity. This new approach can be used to develop customised seed collection protocols, including number of populations, trees and seeds to collect, and the best choice of populations in a species’ range. The team have demonstrated the approach by evaluating ex situ seed collections of Fraxinus excelsior, European ash, a species which is currently in severe decline across Europe from the introduced fungal disease ash dieback. The case study is Kew’s UK National Tree Seed Project (UKNTSP), which has collected approximately 2 million seed from 600 ash trees across Great Britain. 

Overall the study suggests that the UKNTSP work has been remarkably successful, but further seed collections can help more thoroughly preserve this ecologically and economically important species and provide benefits for forestry, natural environments, and ultimately society.

For more information see the article, published in Biological Conservation:

Hoban, S., Kallow*, S. & Trivedi*, C. (2018). Implementing a new approach to effective conservation of genetic diversity, with ash (Fraxinus excelsior) in the UK as a case study. Biological Conservation 225 10–21. Available online