Thousands of trees, including some of the Westcountry's most ancient forests, could be on the brink of destruction from pests and disease wreaking a "devastating" impact on the region's fragile ecosystems.
Conservationists have warned that diseases such as ash dieback and acute oak decline have put at risk trees that have stood as "stalwarts" of their communities for centuries.
Described as the natural equivalent of listed buildings, trees such as the Darley oak, which has stood on the edge of Bodmin Moor in Cornwall for as many as 1,000 years, play a valuable role in boosting biodiversity, as well as featuring in ancient folklore and culture.
There are estimated to be 147 ancient trees in Devon and Cornwall, with a further 1,549 that are classed as notable or veteran.
Tim Kellett, from the Cornwall Ancient Tree Forum, said that ancient trees were under threat for lots of reasons, including land management
"We are learning a lot more about ancient trees and their value to the ecosystem and biodiversity," he said.
"It is a great concern because what we are talking about is trees that are several hundred years old, it's is going to take a very long time to build up that ecology. It's not just going to happen in a couple of decades.
"It's also the social value when you get trees like the Darley oak with lots of history. There could about 100 in Cornwall and it is important that they are well looked after. It would be nice to make sure people look after them."
In total, there are 18 ancient common ash trees in Devon and Cornwall that are threatened by Chalara ash dieback, a fungus which kills ash trees and has arrived in the UK from the continent.
But it is not just ash trees which are under threat from disease, the region's 94 ancient oaks are at risk of acute oak decline and oak processionary moths, and its ten notable or veteran Scots pines are threatened by needle blight.
Juniper, oak, beech and sweet chestnut are all affected by Phytopthora fungi while invasive non-native pests are also a threat, including the Asian longhorn beetle, which attacks most broadleaved tree species. The Government is consulting on bringing in a ban on importing sweet chestnut trees to stop the spread of sweet chestnut blight, which wiped out trees throughout the eastern US and is now infecting trees as close to the UK as France.
Austin Brady, head of conservation at the Woodland Trust, said: "Losing some trees to diseases and pests is all part of life and death in the forest, but to lose our precious ancient trees would be terrible.
"These huge stalwarts have taken centuries to grow and their loss would just be devastating, not only for the landscape, but for the environment."
The Darley oak, which is said to be the oldest living tree in Cornwall, has played a valuable role in its community for centuries, having been used as a venue for tea parties as far back as 1727, until a great canopy section collapsed in the eighties.
It became the subject of local folklore and was said to have special healing properties for various ailments and diseases.
Reputedly, wishes were granted to anyone who passes through its hollow and circles the girth.
Catherine Horrell, who is tree warden for the parish of Likinhorne, near Callington, in which the legendary oak is situated, said she has a tree grown from acorn belonging to the Darley oak in her back garden. She added the tree is really important for invertebrates.
The Woodland Trust is holding a conference in June with some of the top minds in conservation, forestry and tree health, to find a way forward for the country's trees and woods.
In the meantime, it is urging the public to get into the countryside and look at trees for signs of disease, so that experts can get as accurate a picture of the situation as possible. With ash trees coming into leaf, people can begin to spot if ash dieback is present. One of the easiest ways to check for disease at this time of year is to scratch a little of the bark off and if it is green underneath it is healthy, but if it is brown it is not. Diamond-shaped lesions on the trunk, wilting on the leaves, which may become blackened through summer but stay on the branch, and a balding crown of the tree, are all signs of ash dieback.
