Restoring woodlands affected by ash dieback

A tree in summer with two main branches. One has bright green leaves and the other has no leaves whatsoever and is just bare branches. — Tree displaying signs of ash dieback at Devil's Dyke, South Downs | © National Trust Images/Laurence Perry

Ash dieback is a devastating disease that threatens trees and woodlands throughout the country. Changing weather patterns caused by climate change may be exacerbating ash dieback – along with other diseases threatening a range of tree species – at the places in our care.

What is ash dieback?

Ash dieback is caused by a fungus called Hymenoscyphus fraxineus which originated in Asia and spread to Europe via the global plant trade. With its windborne spores the fungus spreads quickly, causing the crown of the tree to die back, often resulting in the death of the tree.

Ash trees like those at Beatrix Potter’s Troutbeck Park Farm are some of our most culturally significant trees. They’ve stood for hundreds of years but many will now be lost forever.

A quote by Luke BarleyNational Trust National Tree and Woodland Advisor

Ash dieback and the changing climate

Historic trees and beautiful woodland – which have inspired the likes of writer Beatrix Potter and landscape painter John Constable – face extinction. Ash dieback may be driven in part by the climate crisis: mild, wet winters create ideal conditions for disease and pests to spread and prolonged drought, flooding and high temperatures also mean that trees are likely to be stressed and more vulnerable to disease.

The death of up to four out of five native ash trees will have a devastating impact on wildlife and many of the landscapes we’ve come to love There a number of species that depend entirely on ash trees, including some rare and important lichens, and the conditions created by the light canopy of ash means ash woods have some of the richest ground flora.

A view of ash dieback from a drone, showing several fallen trees — A view of ash dieback from a drone at Haresfield Beacon, Gloucestershire | © National Trust Images/Mike Calnan

Other tree diseases

It’s not just ash trees that are affected by airborne pathogens; tens of thousands of larch trees were felled across the Lake District as a result of an outbreak of the disease Phytophthora ramorum. A new disease known as Phytophthora pluvialis was discovered in Cornwall which affects a variety of tree species, including pine. An outbreak of the eight-toothed spruce bark beetle in the south-east of England has also raised concerns.

Working to save precious woodlands

We've been working around the country to eradicate trees and woodlands affected by these diseases. In many instances we're replacing them with more climate-resiliant species that will thrive for centuries to come.

Derbyshire Dales and White Peak

The ‘ravine woods’ of the White Peak are largely made up of ash trees which support some of the richest woodland flora in the UK. Around 1,600 ash trees were felled for safety reasons across the Peak District in 2021 and nearly 90 per cent were in the White Peak. This work costs around £250,000 and we're expecting to spend £1m tackling the problem during the next four to five years.

Kent

There’s been a changing of the guard at Cobham Wood near Gravesend. Centuries-old veteran oak and ash trees are gradually being replaced by a new generation of more climate-resilient trees, including the new elm tree cultivar ‘Lutece’, which was developed by breeding four types of elm, two of which are native to the UK.

Lake District

We have a legal obligation to fell all larch trees within 100m of a tree infected by the disease Phytophthora ramorum. The largest area affected in 2021 was Holme Wood above Loweswater, where larch makes up 75 per cent of the woodland. The disease is affecting biodiversity, destroying habitats, taking resources away from daily conservation work and making it harder for us to tackle climate change. Woodlands in the South Lakes have also been badly hit, including Tarn Hows, Coniston, Wasdale, Langdale and Crummock.

Norfolk

We had to clear an area of woodland at Sheringham Park because of ash dieback. In its place, we've planted field maple, beech and other broadleaf trees that will provide autumn colour for generations to come. By making sure more natural light can come through the tree canopy we're also helping flowers and insects to thrive.

Ash dieback and felling on the Ickworth Estate, Suffolk | © National Trust Images/James Dobson

South Wales

Pembrokeshire has suffered badly from the effects of ash dieback this year. This has resulted in a road closure as work was taken to address the problem at Colby Woodland Garden. Sadly, we will be felling around 1,000 trees at Stackpole. Some of the dead wood will be left to create homes for insects, which will provide food for birds and other wildlife. Open woodland glades will also attract butterflies.

Surrey

Locally, the pathogen has caused many trees across the Surrey Hills landscapes we look after to become brittle, risking them becoming unstable or shedding limbs. To protect the public, we’re having to remove specific trees across our various locations in Surrey, including Holmwood Common, Box Hill and Reigate Hill and Gatton Park.

We realise that seeing machinery removing trees in well-loved landscapes is difficult and as a team we find it hard too. The removal of ash trees is an unwelcome, but necessary job and we need to act to ensure people are safe.

In many places we will be leaving most of the arisings to improve our deadwood reserves. Deadwood is vital for woodland ecosystem health and provides habitat and food for many priority species like stag beetles. The new spaces created in the canopy will encourage natural regeneration and provide more light for native woodland plants and flowers to flourish.

Yorkshire Dales

Like in many other limestone and chalk landscapes, ash is the dominant tree species in the Yorkshire Dales, especially on the limestone pavement at Malham Cove. Sadly many of the trees will probably be lost to ash dieback. We're working to recreate woodland that supports nature and adds to the beauty of the area.

Help us restore woodlands

Sadly we're having to fell a record number of trees because of the impact of ash dieback on human safety. The majority of ash trees (75–95 per cent) will be lost during the next 20 to 30 years. As part of our ambition to plant and establish 20m trees by 2030, we're planting more climate-resilient trees and creating woodlands that have a diverse range of species in them.