A £1.25m multi-party research programme, Protecting Oak Ecosystems, has produced what is claimed to be the most comprehensive list yet of all species known to use native oak trees (Quercus petraea and Q. robur), numbering 2,300 invertebrates, birds, mammals, fungi and others.
Of these, 326 were completely dependent on oak, with a further 229 being "highly reliant" on them. The figures do not include any of the bacteria and other micro-organisms also associated with oak.
The programme aims to to improve their understanding of oak-related pests and diseases, and wider ecosystem threats; suppportr natural resource planning; help forest managers maintain oak ecosystem health; and prepare stakeholders for a potential loss, or major decline of oak.
Lead author Dr Ruth Mitchell, of the James Hutton Institute’s Ecological Sciences group, said: "Our really old large oak trees support the greatest number of species. We are currently benefiting from trees established hundreds of years ago."
Oaks are currently at risk from a range of pests and pathogens including acute oak decline, chronic oak decline, oak processionary moth and powdery mildews, though theese are not thought likely to lead to a significant loss of oak imminently.
However oak is predicted to decline in some areas of the UK in the long term, and the trees able to support the greatest number of oak-associated species turns out to be ash - currently declining in numbers due to ash dieback.
Defra biosecurity minister Lord Gardiner said: "I welcome this publication which highlights the importance of addressing the serious threats to our oak trees which would also affect a great number of species that are dependent on them.
"What we learn from this project will feed directly into our Action Oak initiative, a collaboration of charities, government, landowners and research institutions whose aim is to protect the UK’s 121 million oak trees from plant pests and diseases."
The study is published in the journal Biological Conservation.