Shoots of hope for Britain’s cherished ash trees

Ash trees are fighting back against a disease that has ravaged the British countryside, new scientific evidence shows.

When ash dieback arrived in 2012, it was predicted up to 85% of ash trees could be lost. It spread to every corner of the British Isles, causing widespread damage to woodlands.

But now scientists have discovered that ash woodlands are naturally evolving greater resistance to the fungal infection.

The discovery offers fresh hope that the much-loved trees will remain part of the British landscape – but a hope “borne out of the death of a lot of trees”, said Prof Richard Buggs, of the Royal Botanic Gardens Kew and Queen Mary University of London.

He added that other interventions would be needed to give ash trees a helping hand, such as protecting trees from grazing deer and breeding the most resilient trees for future planting schemes.

“We have fresh motivation to look after our ash populations, to protect them from other problems like deer browsing, and to let nature take its course and evolve trees with more resistance,” Prof Buggs said.

The ash dieback fungus originated in Asia and was introduced to Europe about 30 years ago.

Signs of the disease can be seen through withered and blighted leaves. In many cases, the fungal disease will eventually kill the tree.

A study of ash trees at a woodland in Surrey revealed subtle shifts in different genes over time, which should help new saplings fight it – suggesting they were evolving greater resistance to the disease than their predecessors.

Richard Nichols, professor of evolutionary genetics at Queen Mary University of London, said a “tragedy for the trees has been a revelation for scientists – allowing us to show that thousands of genes are contributing to the ash trees’ fightback against the fungus”.

Ash dieback demonstrates how devastating introduced pathogens can be for our trees and the species which rely upon them, according to Rebecca Gosling of the Woodland Trust.

“The findings highlight how vital it is to support natural regeneration in woodlands, furthering our understanding of how to best manage our ash woodlands,” she said.

Scientists had feared the ash would go the way of the elm, which has been almost wiped out by Dutch elm disease.

The loss of the native tree would have also had a devastating effect on biodiversity.