UK local authorities could be facing a bill of billions of pounds as a result of ash dieback disease making trees unsafe near roads and other sensitive areas.
Senior local government figures have called on ministers to allocate funding for the issue in the upcoming Spending Review because councils have not costed for the removal of millions of trees.
Director of trees, science and research at the Tree Council, Jon Stokes has warned that the disease, which is caused by a small fungus, was major issue that councils needed to prepare for now.
'We have a number of local authorities costings, and they range to £6m-£10m up until about £80m. Aggregated from road and rail together we are talking about £4bn-5bn that needs to be spent over the next 10 years making ash safe in transport corridors.
'To try and get control of the processes with ash dieback, there is a health and safety taskforce, set up by [environment department] Defra and other organisations, dealing with highways and railways. We have come together to try and form a national plan to deal with the process.
'We are leading a lot of work alongside Defra on dieback and how it will be managed and impact [the highways] sector. There are loads of ash trees close to the highway, and dieback will increase the risk of the tree falling and safety may decline.'
Mr Stokes said the best estimates suggest there are somewhere between 27 million and 60 million large ash trees in the countryside outside woodlands. This is two or three times the number of trees with Dutch elm disease.
'The estimate is that somewhere between 75% and 90% of those trees are likely to die, and most will die in the next 10 to 15 year period. In some places like here on the south coast that is already taking effect and we are getting large numbers of dead trees by the highways.'
'There are loads of ash trees close to the highway'
One council had said the numbers of trees being blown over in storms and increased from one to hundred.
The Tree Council had worked with Devon, which estimated the number of potential ash trees in the highway at 447,000, with 90% at risk.
The Tree Council has published a toolkit on its website for local authorities, on behalf of Defra and other agencies, to help councils prepare an ash dieback action plan.
Mr Stokes said: 'There are four parts to any emergency planning - awareness, planning, action and recovery. We think that highways managers need to get involved. The government spending review needs to factor in ash dieback because it isn't something [councils] have not costed for. Many local authorities will have started to prepare a plan.'
Norfolk CC has used satellite and lidar technology to develop a risk-based approach to the problem. Models suggest the county could have more unhealthy ash trees than healthy ones by 2022.
The Tree Council has identified four categories of ash tree using quartiles of the canopy. 1 has 100-75%, then 75-50%, 50-25% and 25-0%.
'If the tree is adjacent to a highway or in a place of high risk, once you get past category two is when tree people will start to think, "I am uncomfortable with that near my infrastructure",' Mr Stokes said.
A legal conundrum?
Mr Stokes raised an issue of legal ambiguity: 'When you serve a section 154 notice, it becomes the duty of the landowner to be aware that their tree is a risk. After a period, if the landowner does nothing about it, custom and practice were that [responsibility] defaulted back to the council who then bore the risk do the work and then back charge the person for doing it.
'That's ok with one tree, but when it becomes millions of trees, if I were the landowner, I would do nothing about my trees and let the council deal with it.'
Where it appears to a competent authority for any highway, or for any other road or footpath to which the public has access—
(a) that any hedge, tree or shrub is dead, diseased, damaged or insecurely rooted, and
(b) that by reason of its condition it, or part of it, is likely to cause danger by falling on the highway, road or footpath, the authority may, by notice either to the owner of the hedge, tree or shrub or to the occupier of the land on which it is situated, require him within 14 days from the date of service of the notice so to cut or fell it as to remove the likelihood of danger.