An invasive fungal disease killing ash trees will cost the British economy nearly £15 billion in total, a study has warned.
Ash dieback which is lethal to European ash trees, originated in Asia and is thought to have been brought to the UK on imported ash trees some years before it was first identified in Britain in 2012.
Now experts have calculated a multi-billion pound bill for the disease, with the costs expected will be more than £7 billion in the next 10 years alone.
The biggest cost will be from the loss of benefits that woods and trees provide, such as clean air and water and storing carbon dioxide, the study published in the journal Current Biology found.
Clean-up costs, such as felling dangerous trees on roadsides, railway lines and in towns and cities, will cost some £4.8 billion, researchers from the University of Oxford, Fera Science, Sylva Foundation and the Woodland Trust said.
Much of that burden will fall on local authorities, with an estimate the worst hit, Devon County Council, could face total annual costs from roadside ash trees of more than £30 million, vastly higher than the average council tree budget.
There will also be costs of replanting, research and loss of profits to the forestry sector.
The total bill is estimated to come in at £14.8 billion over 100 years, with half of those costs, £7.6 billion, falling within a decade.
The researchers also issued a stark warning that there are 47 other tree pests and diseases that risk costing £1 billion or more if they become established in Britain.
They have called for a nationwide replanting scheme could reduce the overall cost of ash dieback by £2.5 billion by ensuring that lost benefits are replaced.
A greater focus on and investment in biosecurity and sourcing of safe plant material is needed to keep new diseases out, they warn.
And far tighter controls on imports of all live plants for planting should be introduced, as this is the largest pathway through which tree diseases come into the country, they urged.
The cost of dealing with ash dieback, which is expected to kill 95% to 99% of native ash trees, dwarfs the annual value of the import and export trade in live plants to and from Britain which totalled around £300 million in 2017.
Dr Louise Hill, from the University of Oxford and lead author of the study, said the number of invasive tree pests and diseases were increasingly rapidly, mostly through human activities such as plant trade and climate change.
“Nobody has estimated the total cost of a tree disease before, and we were quite shocked at the magnitude of the cost to society.
“We estimate the total may be £15 billion – that’s a third more than the reported cost of the foot-and-mouth disease outbreak in 2001.
“The consequences of tree diseases for people really haven’t been fully appreciated before now.”
Dr Nick Atkinson, senior conservation advisor for the Woodland Trust and co-author of the paper, said: “When ash dieback first entered the country, no one could have fully predicted the devastating impact it would have on our native habitats.
“To see how this has also affected our economy speaks volumes for how important tree health is, and that it needs to be taken very seriously.”
To avoid further economic and environmental impacts, more needed to be invested in plant biosecurity measures, including better detection, interception and prevention of pests and diseases entering the UK, he urged.
He added: “We need to learn from past mistakes and make sure our countryside avoids yet another blow.”
A spokeswoman for the Environment Department said: “Since ash dieback was identified in 2012, we have invested more than £6 million in ash dieback research and £4.5 million to strengthen border security.
“We currently have some of the strongest import controls in Europe.”
She said the Government was funding research to make ash trees resistant to the disease, supporting replanting with other tree species, and helping local authorities manage the disease.
“We will continue to do everything we can to protect our trees from pests and diseases, as set out in the Tree Health Resilience Strategy published last year.”