“Trees are my temples and forests are my cathedrals”
[Mikhail Gorbachev, 1997]

A...I like a fine prospect, but not on picturesque principles. I do not like crooked, twisted blasted trees. I admire them much more if they are tall, straight and flourishing. I do not like ruined tattered cottages. I am not fond of nettles or thistles or heath blossoms.....@. [Jane Austen, Sense and Sensibility, 1811]

Ancient Trees

Ancient trees are increasingly highly valued. Many people, but not everyone, would claim that they are beautiful, awesome, even numinous. They are living documents of past lives, landscapes, climates and ecologies. Above and below ground level, as they pass through the natural processes of physiological maturity, senescence and death, they host complex, changing communities of organisms. Specialists will usually concede that we know very little about most of these organisms. 

Defined biologically, an ancient tree is not what most people imagine and it may not be spectacular or conventionally beautiful. It is any tree in which the original crown has died or broken up and a new, smaller, lower crown has subsequently developed. This only happens with open grown trees. Ancient trees show obvious signs of decay with serious amounts of dead wood. They are now relatively rare but we have a large proportion of the European collection in the UK. It is the management of these biologically ancient trees that I will consider.

Three Principles of Ancient Tree Management

Provided they have sufficient space around them, in many ways the best management is to leave ancient trees alone. Much of what we value in them is intrinsic to the natural processes of life. Breaking-up, collapse and death are part of the tree cycle. The first principle of ancient tree management is to leave them alone unless there is a pressing and persuasive reason for intervention and a good chance that the intervention will be successful.

But, assuming trees last long enough to become ancient, human activity will usually impact on them in some way. Some conservationists are instinctively interventionist, some farmers want to feed cattle under them, plough close to their roots, drain the surrounding land, fertilise and spray adjacent crops; visitors park their cars below them, workmen dig trenches for services or re-contour the soil levels and foresters in the past may have established plantations around them. All of these activities can seriously damage the tree and the associated plant and animal communities. So the second principle is, so far as possible, to remedy past damage and to protect them and their successors, the ancient trees of the future, from further damaging activities.

That means knowing where they are, what is their condition, what is the risk of damage and how important they are both visually and ecologically. Collecting information through survey and deepening our knowledge of the ‘resource’ helps to ensure that we can protect ancient trees adequately, nurture the next generation and learn a little more about tree ecology. We also need to share our knowledge and raise awareness of what activities can damage trees. So the third principle is to build up knowledge and share understanding.

Three Management Issues:

Public safety is the most obvious and sometimes the most contentious justification for intervention management. Most of the Trust’s ancient trees are accessible to the public and we have a legal obligation to safeguard visitors. Nevertheless our aim is to avoid all non-essential tree work.

For some years now Trust staff have followed a rigorous programme of tree inspection in public places. Staff who will decide on remedial action are required to attend a four day course which covers ancient trees, tree physiology, tree ecology, inspection procedures and a consideration of the appropriate options for remedial action. In the case of ancient trees, wherever practical, we would modify the arrangements for public access rather than undertake extensive tree work.

Many of our ancient trees are in historic designed landscapes. Landscape specialists argue that in most eighteenth century parks biologically ancient trees are unacceptable. Decay and death are not consistent with the eighteenth century ideal of a classical landscape. (Fortunately they are much more compatible with the picturesque style adopted in the nineteenth century). 

There has been much debate in the Trust about this. So far our solution has usually been to allow ancient trees and dead wood in eighteenth century parks only away from the main views and vistas, but this tension between different conservation values is essentially unresolved.

Management for habitat succession is another difficult issue because we know so little about the organisms associated with ancient trees. Imaginative managers create new habitat features or take steps to prolong the life expectancy of favoured trees, usually by re-pollarding or crown reduction, in an attempt to retain a succession of fungi, lichen or invertebrate habitat across a whole pasture woodland. 

It is certainly not desirable to preserve the life of ancient trees solely because we don’t want them to die. Senescence and death, as I have said, are a valued part of the natural tree process. It is also debatable, in my view, whether work to promote the short to medium-term survival of associated communities is worthwhile where there is no possibility of sustaining suitable habitat in the long term. 

Continuity and succession of ancient trees may not be possible. Often there will be an unavoidable gap once existing ancient trees have died. In such situations succession of habitat might only be achieved artificially. It may be feasible to damage younger adjacent trees to create cavities which will lead to the early onset of decay or we may favour trees which can host key species while still quite young; fifty year old sycamore, for example, has a bark pH similar to ancient oaks and provides a suitable substrate for similar lichen communities. Such actions may be valid, but it is hard to be sure what they really achieve.

In conclusion, we value and sustain ancient trees but we are all pretty ignorant about the communities associated with them. The three principles outlined above should guide management, but there are many unresolved dilemmas. For the time being, at least, the best prescription is for continued research coupled with intelligent, intuitive management. 

Details of National Trust Tree Inspection procedures, Guidelines on Ancient tree management and other Trust Tree and Woodland guidance can be found on our Environment and Conservation website: www.nationaltrust.org.uk/environment