Thousands of "precious" ancient trees could be at risk from pests and diseases such as ash dieback and acute oak decline, experts have warned.
Described as the natural equivalent of listed buildings, ancient trees have stood for hundreds of years, watching over historic events and playing a role in folklore and culture.
But the majority of the 115,000 ancient, veteran or notable trees registered on the Woodland Trust's Ancient Tree Hunt website could be facing the threat of diseases and pests, a loss that would be "devastating", said the conservation charity.
Some, such as the 11-metre girthed Big Belly Oak in Savernake Forest, Wiltshire, which is thought to have stood since the time of William the Conqueror, have acted as significant landmarks for local people for centuries. Ancient trees also provide an important habitat for a host of different species, from bats to bugs and fungi.
Austin Brady, head of conservation at the 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."
In total, almost 84,000 ancient trees are at risk, including 7,000 ash trees threatened by Chalara ash dieback, a fungus which kills ash trees and has arrived in the UK from the continent, where it has caused immense damage in some areas.
But it is not just ash trees which are under threat from disease, with ancient oaks at risk of acute oak decline and oak processionary moths, and Scots pine 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. The Woodland Trust is also raising concerns about the fate of ancient trees along the planned HS2 high speed rail line.
But the more immediate threat are pests and diseases, and the Woodland Trust 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, and a balding crown of the tree are all signs of ash dieback.