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Ancient trees

Very old and ancient trees are irreplaceable and often have a history stretching far into the past. The older the tree , the more important to wildlife it becomes.

What is an ancient tree?

An ancient tree is one that has been allowed to grow old and with great age comes great habitats for wildlife. It is in the third and final stage of its life and will have developed lots of niches that wildlife will settle into – such as cavities for bats and birds, and decaying wood for invertebrates.

Ancient trees have passed maturity and are old in comparison with other trees of the same species. They will probably have a wide trunk, which will likely be hollow. And like humans trees shrink with age so they may have a small canopy.

This isn’t the end of the line for the ancient tree. Even though they are in the third and final stage of their life, and they are in the process of dieback and decay, it may go on for a long time.

How old is an ancient tree?

The age at which a tree becomes ancient varies from species to 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.