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Individual ancient trees are valuable wildlife habitats.
When they occur in clusters or groups they are even more valuable. Especially where there is a history of long-lived trees stretching far into the past. These are defined as areas of “old growth”.
What are ancient trees?
Ancient trees are of interest biologically, aesthetically or culturally because of their great age. They are in the third and final stage of their life, which means they are in the process of dieback and decay. This stage of life can go on for a long time.
The age at which a tree becomes ancient will vary with species. Some, such as oak and yew, are naturally more long-lived than others. The Fortingall Yew in Perthshire, Scotland, is perhaps the oldest tree in the UK. Modern experts estimate it to be between 2,000 and 3,000 years old, although some think it could be far older – maybe even 5,000 years old.
Very often ancient trees are found outside woodland. Many survive in the remnants of royal hunting forests, and ancient wood pasture and parkland. Individual ancient trees exist in urban parks and housing estates, on farms, in ancient hedges, and in churchyards.
The ecology of ancient trees
Ancient trees are often impressive and complex structures. The fact that they are in the process of decline and decay means there are plenty of nooks and crannies to harbour wildlife. The hollowing of trees by fungi creates habitats for a variety of vertebrate and invertebrate species. Chicken-of-the-woods is a fungus that causes brown rot in the heartwood of trees. This, in turn, is favoured by the vulnerable cardinal click beetle. The fruiting bodies of fungi also provide food for red squirrels, badgers, wood mice, and some beetles and slugs.
Saproxylic invertebrates rely on dead or decaying wood for some of their life cycle. Possibly the best-known saproxylic invertebrate in Britain is the stag beetle. Its larvae feed on dead and decaying wood. Many of these invertebrate species are in decline because of the shortage of deadwood habitat in the UK.
Insects associated with ancient trees provide food for other species, like woodpeckers. Rot holes provide homes for brown long-eared bats, while tawny owls use large holes created by the loss of large limbs from mature trees. Hollows created in the trees also make great habitat for barbastelle bats, which roost deep inside in winter. Hornets also make nests in hollow trees.
Many lichens, especially rare and specialist species, need the bark of ancient trees. The lichen, Lobaria virens, grows on the bark of mature deciduous trees. It is particularly sensitive to atmospheric pollution and loss of habitat.
Other notable trees
Veteran trees are those in the mature stage of life, which are not yet ancient. They also have important features including hollowing and deadwood, and the associated species. They are the ancient trees of the future and should also be protected.
More than 120,000 individual ancient, veteran and notable trees have been recorded.
More woodland habitats
Find out more about the other types of woodland across the UK.