Sir Nicholas Soames: To ask the Secretary of State for Environment, Food and Rural Affairs, what estimate she has made of (a) the geographical extent of ash dieback disease and (b) its effect upon woodland and the number of ash trees in the UK.

Rory Stewart, Parliamentary Under Secretary of State for Environment and Rural Affairs: The spread of ash dieback has been progressing much as we expected. This is based on the scientific modelling of the outbreak undertaken by Cambridge University.

The Government has a comprehensive surveillance programme in place to monitor the infection. The level of infection is widely variable in areas, with the south-east of England being worst affected. A map showing outbreaks is updated regularly and available online at: http://chalaramap.fera.defra.gov.uk/

Ash is the third most prevalent broadleaved species in GB woodlands (estimated stocked area of ash is 142,000 thousand hectares, with an estimated 126 million trees) and as a proportion of total UK woodlands is around 4.7 percent (142,000 hectares as a proportion of three million hectares). Ash is also very common in non-woodland settings and it is estimated that there are 27-60 million ash trees[1] in non-woodland environments (parks, gardens, lining roads and railways).

Local effects on landscapes and woodlands will mostly be gradual and mitigated by other tree species taking the place of ash trees. Natural tolerance to the disease does exist and the UK is leading the way on the work to identify resistant strains.

[1] The Tree Council (2015): Chalara in Non-Woodland Situations. Findings from a 2014 study.

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