‘10,000 oaks of 100 years old are not a substitute for one 500 year old oak’ Oliver Rackham ¹

So how many oaks of 100 years old would it take to substitute for a single oak of 1000 years old? Despite an English Nature Ancient Woodland Inventory and a Forestry Commission National Inventory of Woods and Trees, at the start of the 21st century, we know remarkably little about our ancient tree resource. We don’t even know how many 1000 year old trees there are alive in the UK. There are, however, probably thousands of old oaks between 500 and 1000 years old. Some are named trees such as the Domesday Oak of Ashton Court in Bristol but many of them are un-remarked and most are entirely unprotected except through the goodwill of their owners. 

Generally speaking, the older and fatter a tree is, the more important it is for wildlife. And where a number of ancient trees are gathered together, the more there are, the more valuable they are for biodiversity. However to put this into perspective, a site in Gloucestershire with just eight ancient trees has recently been found to be of international importance for its rare and endangered insect species alone. Despite its obvious importance for biodiversity, this site is threatened by development and the ancient trees will be fragmented and isolated in a major housing scheme if the planning application is approved. 

Of the known ² sites in the UK and Ireland, 10 sites are known to have more than 1000 ancient trees, about 35 sites have between 100 and 1000 and a further 250-300 between 20 and 100 trees. There are many sites which are yet to be included in the Ancient Tree Forum’s inventory. New sites are being added at regular intervals as we learn about them, often when they are threatened by development. Unless such sites are designated as SSSIs, and very few are, the trees and their habitats are extremely vulnerable. It is all too easy to squeeze a few houses between the trees, plough up the ground around them for arable crops or plant young conifers in the spaces between them. Our ancient trees, even individual trees. ³

Some trees may even be as valuable in death as in life. Their decaying heartwood can linger for many years before it is gradually recycled into the ground. However this should not encourage us to turn a blind eye to actions that will result in the premature death and decline of our ancient trees. Instead we should be finding ways of prolonging their lives as long as possible. The book – Veteran trees: a guide to good management (2000), available from English Nature, has practical up to date information on managing our ancient trees.³

Ancient trees are the pinnacle of important decaying wood communities. They provide extraordinary niches for an exceptional range of nationally and internationally scarce species of wildlife. The Moccas beetle is only found in one tree at Moccas Park in Herefordshire, the violet click beetle from only two or three locations in the UK. These species rely on the decay process in the heart of the trees for their larval habitat and flowering shrubs in the surrounding environment for their adults to feed on nectar. The UK holds more than 25% of the world population of Podoscypha multizonata – a rare fungus found on the roots of old oak trees in parklands. This fungus is now being proposed as a scheduled species on the European Bern Convention. We know so little about these animals and fungi but for each and every one associated with old trees, there is a unique life cycle requiring a sustainable supply of specialised habitat for their survival. 

What do the shapes of our ancient trees of today and their associated wildlife tell us about the habitats and landscapes in which they have lived in the past? It only takes one ancient tree to help us see back in time to a working common, a Tudor ceremonial park, a mediaeval wood pasture, an Anglo-Saxon royal hunting forest or even allow us to glimpse the original Wildwood as seen by Neolithic man. Our pollards are a characteristic feature of our most cherished landscapes and as old working trees ⁴ are full of meaning and clues to the way we lived our lives in previous centuries. Our old trees are historic living monuments of incredible cultural value and once lost they are impossible to replace.

Our oldest oak trees which once had full open grown canopies, but are now ‘hunchbacked, misshapen oak men ⁵’, must have started and lived their lives in open grazed woodland. Many would have started from acorns buried by jays and these open grown trees have a significant proportion of the rare species associated with them which require either more or less dappled shade as found typically in wood pastures or parkland. To have evolved such relationships has taken thousands of millennia and they cannot be a result of recent man made landscapes. 

The evidence from modern biodiversity therefore strongly supports the case that our original wildwood was wood pasture which contained significant areas of scattered trees and large glades. It fits well with the challenging views put forward by Frans Vera ⁶ that our original landscapes of Europe were actually far more park-like in structure than frequently thought. If this is correct our wood pasture and parkland sites with old trees which have a history of old trees reaching into the past, are our old growth woodlands and are of European and international significance. It is salutary that so few of these sites are recognised as such let alone given status by any conservation designation. 

How can we best conserve this special biodiversity? The Woodland Trust has outlined its proposals in Space for Nature ⁷- available from the Trust or can be downloaded from the web site www.woodland-trust.org.uk. The Trust argues that we need urgently to identify old growth sites with ancient trees and to buffer and extend them, ideally by the creation of new wood pasture using large organic grazing herbivores as key agents for nature. In the meantime we need to find ways to keep our ancients alive long enough for the new generations of trees to reach old age and provide a sustainable supply of dead and decaying wood for wildlife associated with them. 

If you know of ancient trees which are threatened or want to check that a site is on the inventory then please contact the Ancient Tree Forum via their web site www.ancient-tree-forum 

1. Rackham, O. (1986) The History of the British Countryside. Dent
2. Alexander, KNAA, (unpublished). Significant sites for old growth communities in lowland Britain and Ireland – a working document.
3. Green, EE (2001) Comment: Should ancient trees be designated as SSSIs? British Wildlife 12:164-166.
4. Green, EE (1996). Pollarding –origins and some practical advice. British Wildlife 8:100-105
5. Kilvert, F. (1876) Diary of Francis Kilvert. In Harding, P., Wall, T. (2000) Moccas: an english deer park. English Nature.
6. Vera, FWM (2000). Grazing ecology and forest history. CABI International
7. Woodland Trust (2002). Space for Nature