Disease-resistant English elms are being planted in Sheffield as part of a national trial to combat the effects of Dutch elm disease.
The fungal disease has killed more than 60 million trees in the UK since it arrived in the 1920s.
Experts say outside a cordon sanitaire in Edinburgh and Brighton there are fewer than 1,000 old elms in the UK.
The Sheffield initiative will see 24 disease-resistant saplings planted at Greno Woods nature reserve.
They will be grown in a small area of ancient woodland provided by Sheffield & Rotherham Wildlife Trust following the first planting on Monday.
Dr David Herling, who is the national lead for the project, said: "The idea behind the eight experimental plantations is to establish a range of resistant elms across varying climate and soil conditions countrywide, from Exeter to Edinburgh."
He said the trial would be used to find which varieties were suitable for wide-scale planting.
Some of the varieties being planted in Sheffield are so new they do not yet have names, he added.
Other trials are taking place in Monmouthshire, Devon, Middlesex and Northumberland.
Highgrove, Kew Gardens and the Royal Botanic Garden Edinburgh are also taking part.
The latest, the Sheffield initiative, was crowdfunded by enthusiast Paul Selby, who raised £700 in two weeks to support the planting.
He said he remembered seeing "wonderful English elms" die during the epidemic, and wanted to do something to combat the devastating effects of Dutch elm disease.
The first of the Sheffield saplings was planted at a ceremony earlier.
A killer disease
- More than 60 million elm trees have died in the UK since the 1920s as a result of Dutch elm disease
- As a result, outside the cordon sanitaire zones in Brighton and Edinburgh, fewer than 1,000 old elms are left in the whole of the UK
- The disease is now endemic, moving in waves, and is still relentlessly killing the remaining 1,000 old elms, as well as tens of thousands of young saplings, each year
Source: Sheffield & Rotherham Wildlife Trust