Britain, along with Spain and Greece, has one of the highest populations of veteran trees in Europe. Veteran trees are valuable for many reasons:
- They support a rich invertebrate fauna, both of general and specialist species. The nooks and crevices provide nesting sites for birds and small mammals.
- They support a rich flora of lichens and mosses, both of general and specialist species.
- Veteran trees represent a gene pool which may link back to the trees of the wildwood.
- They are living remnants of past land use and management.
- Many veteran trees are remarkable and beautiful.
Veteran trees can be found in many places, and not only in ancient woodlands. Boundary banks, old hedgerows, river banks, churchyards, wooded commons and parkland, including urban parks, are sites where veteran trees can be found. Continuity of ownership is often a significant factor, as new owners tend to want to make changes which may include removal of old trees.
Assessing value and age
A rough rule of thumb can be adopted to assess the value of a tree, for example an oak, in relation to size:
- Trees with a diameter at breast height of more than 1.0m (girth 3.2m) are potentially interesting.
- Trees with a diameter of more than 1.5m (girth 4.7m) are valuable in terms of conservation.
- Trees with a diameter of more than 2.0m (girth 6.25m) are truly ancient.
Absolute age is not necessarily a good indicator of ancient status, as different species have different life spans. Thus willow and birch are short lived and specimens over 100 years old are valuable, whereas beech and oak only start to mature at 200 years. Yew is the most long-lived native tree.
Assessing the age of a veteran tree is not easy. Core samples can be taken, but as many veterans are partly hollow or rotten, this will not tell the whole story. Coring also damages the tree. Counting the rings on major branches, either fallen or being removed as part of essential management work, can give an estimate, although the branch may have been produced at a time after the original growth of the tree.
A rule of thumb is that 25mm (1”) of girth at breast height is equivalent to one year’s growth for a free standing tree, and 13mm (1/2”) of girth at breast height is equivalent to one year’s growth for a tree in woodland. This can be applied to uncut trees such as oak in middle age, but is of limited value for older trees. Trees that have been pollarded or undergone natural crown loss are impossible to age by girth, because these factors will have influenced girth increment.
Threats to veteran trees
- Veteran trees may be cut back or removed altogether where there are worries about safety or tidiness. Old hollow trees with reduced crowns are in fact often safer than mature ones with a full crown.
- Compaction from car parking or trampling around the tree can damage the root system.
- Inappropriate management such as filling cavities with concrete, or unskilled tree surgery. Pulling away ivy, removing dead wood and other ‘tidying up’ is misdirected management.
- Changes in the water table can cause stress to the tree.
- Changes in the surrounding vegetation. Lack of grazing or new planting can cause the veteran to become shaded by other tree growth. Conversely, opening up a previously shaded veteran by removal of surrounding trees can also be damaging.
- Many veteran trees were pollarded in the past, and if this management lapses, the tree is more likely to become unsafe and require felling.
- As the number of veteran trees reduces, the remainder become more isolated, and the ability of organisms to spread to other veterans is therefore lessened.
Management of veteran trees
The general principle is that veteran trees are identified, recorded and checked at regular intervals. Active management should only be carried out if necessary for public safety, or where the threats identified above require action to be taken. Veteran trees are exceptionally hazardous to work on, and pollarding, removal of overhanging branches or other practical work should only be undertaken by trained and experienced operators.
When assessing a veteran tree, both the individual tree and its surroundings need consideration. Trees are individuals, and every tree needs looking at individually. A management plan will be needed which involves assessing the site, deciding on priorities, implementation, monitoring and review.
For full details see Veteran Trees: A guide to good management (Read, Helen, 2000).
