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Ash trees

Ash trees form a significant proportion of Cambridge’s urban forest. They grow well in the area’s rich soil and comparatively dry environment.

We estimate there are about 53,000 ash trees in the city, which is about 22% of the city's 240,000 trees.

Mapping ash trees

We know where all the publicly owned ash trees in Cambridge are. We need your help to find every ash tree found in gardens and on private land, or in wild areas, and add them to our tree map.

If you can help, download the Curio-xyz smartphone app and sign up to our ash mission. Add any ash tree you find – it doesn’t matter how big it is or how healthy it is.

Visit Curio’s help page and Curio’s YouTube channel to find out how the app works, including how to add trees and join missions.

If you need some help getting started, join us on an ‘ash hunt’, where we’ll show you how to identify ash trees and use the app. We’ll start running these in June 2020, when the trees are in leaf.

If you want to help us cover as much of the city as possible, you can become an ‘ash ambassador’.

As an ambassador, we’ll let you choose an area of the city and ask you to search it for any ash trees that are not yet on the map. We’ll give you all the information you’ll need to help you on your way. We’ll publish more information about this scheme soon.

With the information you gather, we’ll be better able to understand the threat ash dieback poses in Cambridge. We’ll be able to plan a resilient urban forest, helping to minimise the disease’s impact on the city’s biodiversity.

Ash trees in your garden

The Forestry Commission advises you to keep an eye on any ash trees in your garden.

There’s no need to remove a tree if you think it might have ash dieback – leaving it standing helps us find resistant individuals. It also preserves the habitat that the tree provides for as long as possible.

If you have safety concerns about a tree, you should ask a professional to assess it.

Ash dieback disease

Ash dieback is a fungal disease that attacks the tree’s leaves and causes the infected branch tips to wilt and die. It has affected mainland Europe since the 1990s, and was first confirmed in the UK in 2012. It has since spread to Cambridge.

There is no cure for ash dieback. Infected trees will die within 10 or 20 years, although younger trees can die in as few as two years. Experience from Europe suggests that about 90% of all our ash trees are likely to become infected and die.

Some ash trees exhibit varying degrees of resilience to ash dieback, though. Research in Denmark shows that about 10% of trees have some resistance to it, and 1 or 2% are highly resistant.

Developing a cure for dieback, or new varieties of ash that are resistant to it, is expected to take many years.

In the meantime, we’re working to assess and understand the extent to which dieback is likely to affect Cambridge.

And we’re working to limit the damage we expect it to have on the city’s trees. When we plant new trees, we choose species that will grow large canopies and are good at adapting to a changing climate.