5th December 2012

Ash trees make an important contribution to biodiversity and wildlife habitat and this includes use by bats for roosting where suitable opportunities arise. The recent confirmation of dieback in ash trees (Fraxinus excelsior) has implications for bats and UK biodiversity from the loss of trees to the disease and potentially from the measures put in place to limit the disease spread. BCT is working with the Forestry Commission to assess the situation as is it develops and put protocols and procedures in place that ensure that whilst carrying out the vital work to control the spread of the disease, that bats are protected.

The disease caused by the fungus Chalara fraxinea causes leaf loss and crown dieback in affected trees, and it can lead to tree death. It is a significant threat to one of our widespread native trees. Ash is the third most common broadleaf native tree species in Great Britain after oak and birch and is the predominant tree species in approximately 129,000 hectares of woodland in Britain. The fungus has caused widespread damage to ash tree populations in continental Europe and has the potential to kill millions of ash trees if it becomes widely established in Great Britain. The spread of this disease would pose a serious threat to associated biodiversity, including bats, and measures to prevent its spread are imperative. However, the potential for large-scale destruction of mature ash trees has raised concerns about the impact on roosting bats.

The current situation in December

The reported 100,000 trees already destroyed were all young transplants and nursery stock that were known or likely to be infected with C. fraxinea. Bats roost in mature ash trees and to date no mature trees were included in the destruction measures.

Initial work has focussed on identifying the locations where this disease is present. Initially this disease was thought to be, largely restricted to Norfolk and Suffolk. However, surveys carried out in recent weeks have found that its occurrence is more widespread across England including counties such as Yorkshire, Berkshire, East Sussex and Kent. It is thought likely that Chalara has been in this country for at least 2 years but was only recently discovered.

What happens next?

  • Any newly planted diseased trees or diseased trees in nurseries are being traced and destroyed.
  • If the disease is found a containment notice will be issued to prevent plant material being moved off site.
  • Mature trees will not currently be removed, as it has been acknowledged that they are valuable to wildlife, take longer to die and can enable more to be learnt about genetic strains that might be resistant to the disease.

Although there are currently no immediate plans to remove infected mature ash trees, the Forestry Commission and BCT will continue to work closely together to produce a protocol that would be effective in i) Controlling the spread of disease and (ii) Protect bats should the ash dieback situation change or in readiness for any similar future tree disease incidences.

You can find out more about Ash dieback and the latest news from the Forestry Commission here www.forestry.gov.uk/chalara

We will keep the BCT website updated with further developments.