Enfield Chase: The sad demise of unusual and ancient ash

THIS is a story about a very old ash (Fraxinus excelsior), not growing in woodland and not a coppice stool, but in a tree-studded meadow with branches reaching out to form a broad canopy, just like an English oak growing in the same open-aspect situation. It was for this reason – together with the tree’s deeply furrowed bark, a characteristic of very old ash trees – that I initially mistook it for an English oak. I had walked by hundreds of times on my way to school in the 1960s not knowing a truly remarkable ash was just 50 yards away.

Located in a meadow at Potters Bar alongside the ‘Great North Road’ (A1000) in Hertfordshire, it stood proud as a native monument fighting for life on the Morven Park Estate, owned by the National Trust since 1930.

By 2003 it still supported a few leaf-bearing branches, but was visibly in retreat each year. That said, the tree had done outstandingly well and was way past the normal sell-by date for Fraxinus excelsior in this part of southern England. It was a prime example of how common ash, when growing in an open aspect such as wood pasture, spreads out and develops a form, shape and structure completely different to that displayed by woodland ash. 

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The tree was clearly old, especially for common ash. Standard ash trees hardly ever feature in discourse on exceptionally old trees in the way of oak, yew, elm or sweet chestnut. But did it qualify for ‘ancient tree’ status? 

According to the Woodland Trust and Ancient Tree Forum, the term ‘ancient’ used in this context has no precise definition, but covers trees defined by three guiding principles:

• Trees of interest biologically, aesthetically or culturally due solely to age. 
• Trees in the ancient stage of their life. 
• Trees that are old in relation to other specimens within the same species.

All ancient trees are of historic interest, they say. This is because each one is a survivor from the past and a relic of a former landscape. As such they are a valuable part of our cultural heritage. The following is an appraisal of the ash tree using these guiding principles.

THE ENFIELD CHASE

The ancient ash tree was finally toppled in autumn 2009 with the resident herd of cattle apparently helping the tree on its way down. (Image: FJ)

The tree-studded meadow is almost certainly a relic of the ‘Enfield Chase’ first enclosed around 1140 as a ‘Royal Hunting Ground’, described in the 16th and 17th centuries as a mixture of forest and wood pasture for use by kings and queens including Henry VIII, Elizabeth I and James I, for hunting fallow deer and wild boar.

The Enfield Chase covered most of the ‘Edmonton Hundreds’, one of six divisions of Middlesex comprising the parishes of Enfield, Hadley, South Mymms, Edmonton and Tottenham in 31,000 acres across the north-east part of the county. It stretched 8.5 miles from the Essex Forest of Waltham in the east to the parish of Hatfield (Hertfordshire) in the west, varying in depth from 3.25 to 6 miles. 

An Act of Parliament in 1777 resulted in a second enclosure for the Enfield Chase.

Enfield Parish received 1,700 acres of the spoils, with the remainder (except five square miles retained by the Crown) divided between the surrounding parishes of Edmonton, Hadley and South Mymms.

The area covered by the original Enfield Chase corresponds to today’s London Borough of Enfield and small parts of the London Borough of Barnet, and Hertsmere and Welwyn and Hatfield districts in Hertfordshire. The stag on the coat of arms of Enfield Borough Council refers to the Enfield Chase and its original function as a royal hunting ground. The once-famous Enfield Chase Staghounds were disbanded soon after WWI.

Many trees including the common ash have clearly thrived for centuries in this pasture, sustained by grazing cattle. Hadley Common/Hadley Wood, documented as the last authentic two per cent of the Enfield Chase, is just three miles south. Other very similar locations recorded as having been part of the Enfield Chase and still described as classic wood pasture exist in the surrounding area. Most are found within estates or on commons like Trent Park, Whitewebbs Park and Forty Hall (London Borough of Enfield) and Monken Hadley Common (London Borough of Barnet), now strictly preserved under local authority control. All evidence suggests this wood pasture on the Morven Park Estate in Potters Bar was within the extreme western reaches of the original Enfield Chase.

THE ANCIENT ASH TREE

Breakage and rupture of deadwood provided niche sites for nesting birds and other wildlife but by the same token entry points for microbial pathogens. (Image: FJ)

The ash was in stable pasture with clusters of trees and single specimens including ancient oaks, common lime, and white-flowered horse chestnut. The only recorded English elm, a mighty specimen around 200 years old, succumbed to Dutch elm disease in the 1970s. 

The land is on heavy London clay and slopes down to one side where there is a natural pond surrounded by mature horse chestnut and common lime trees and from which the cattle drink. Hedgerows around the wood pasture comprise a range of species including hawthorn, blackthorn, holly and crab apple, with a distribution suggesting the oldest were originally planted in the 18th century.

Common ash trees are documented as living up to 300 years, but few (except coppice stools) reach such an age, typically starting to decay after 200 years and dying within another 50. The dimensions of this grand old tree suggest the ash ‘key’ (seed) that unlocked its long life germinated before the 1777 enclosure of the Enfield Chase.

Tree diameter at breast height was a yawning 1.5 m+ and the circumference an arm-stretching 4.8 m. Common ash rarely attains 1.5 m diameter so this tree was clearly something special. According to Leicestershire Biodiversity Action Plan, an ash tree only has to be 3.2 m in circumference to qualify as ancient, so this one qualifies with ease. This compares with 3.77 metres for other species like English oak and European beech. The bark is heavily fissured to depths of 3 cm.

The tree clearly achieved an outstanding size. Within the surrounding area, such bole dimensions are only normally seen in ancient oaks growing in an open aspect. 
Other mature ash trees existed as hedgerow trees along the boundaries of the wood pasture. They lacked this tree’s extreme spreading structure and were nowhere near as old. Common ash is ubiquitous in the district as a hedgerow tree and in woodland. Common ash together with beech, hornbeam and oak is listed as one of four core species in Hadley Wood (three miles away), recognised as the last surviving original fragment of the ancient forest of the Enfield Chase.

In spite of its advanced decline, the ash remained a wide-spreading specimen hanging on in moist fertile soil. It was clearly unencumbered by other trees, unlike woodland ash, or cut back like ash trees in the hedgerow. Two very large and low-positioned limbs (1–2 metres from soil level) protruded horizontally to a distance over 10 m from the trunk. By 2007 they were completely dead and stretched out like two long arms encrusted with green and yellow lichen. Later that year, one failed two-thirds along its length like a brittle bone unable to support what was still a considerable weight. 

Both of these horizontally displayed branches originated from one side of the tree, creating an imbalance and causing it to lean slightly. The tilt was clearly not enough for the tree to succumb to the 1987 ‘hurricane’, or a severe storm in January 1990 that demolished a large three-storey brick-built block at a secondary school a quarter of a mile away, ripping off the entire roof.

The few shoots and leaves appearing in May 2008 were confined to the last two living vertical limbs. 2008 looked like the tree’s last season, but I had been saying that for the previous five years. Ash thrives in wet soils and two successive wet summers (2007 and 2008) may have postponed its end. 

In its twilight years, the old ash tree was providing an important habitat for scores of insect species and other invertebrate creatures. Birds like blue tits, great tits and starlings made nesting sites of the cavities created, including those made by woodpeckers. Though not providing much shade, the tree appeared to be a social gathering place for the cattle herd at particular times of the day. 

By 2008 the tree was in its last throes and everything seemed to be closing in for kill.

It was infected with a range of basidiomycete fungi expressing their sporophores (reproductive structures) as bracket fungi. There were thick white and orange bracket fungi around the tree collar and lowest metre of the trunk. 

Others, light brown in colour and more akin in shape and form to mushrooms, were growing higher in the tree. A profusion of dome-shaped toadstools burst through the ground in October 2008 and were in line with the large lateral roots, indicating root disease caused by yet another basidiomycete fungus.  

A large bleeding canker indicated other fungi or perhaps bacteria at work under the bark, and the dead lower limbs were thickly encrusted with green and yellow-orange lichen. Wild mammals had started to burrow underneath the root flares and collar, and woodpecker activity was increasingly evident high in the tree. The cattle appeared to be using the bole as a rubbing site.

The canopy was way beyond the stag-head stage and its dead branches stood stark against the angry sky like the outstretched arms of a drowning man. The National Trust pruned the tops of the vertical branches and sawed off one long-dead horizontal branch halfway along its length, thereby removing a potential hazard to the public as well as livestock. The essential point, says the Woodland Trust/Ancient Tree Forum, is that trees are checked at regular intervals and management carried out only if it is necessary. This appeared to be the strategy that was adopted, but sooner rather than later something more decisive would be required.

The wood was too far gone for use as timber, with polypore fungi almost certainly causing extensive rot of the heartwood inside. One could only hope the National Trust, after making the tree safe, would adopt the same policy as for expired oak and lime trees nearby, leaving the lower trunk in situ to provide habitat continuity for the wealth of living organisms already making use of it in its dying days, and the invertebrate animals and microbes that could to colonise and help recycle the wood.

END OF THE ANCIENT ASH

The ancient ash tree supported a number of large bracket fungi which clearly contributed to its demise. (Image: FJ)

A combination of the elements and a herd of cows sealed the fate of the ancient ash.

Two snow falls, unusually heavy and one extremely unseasonal (31 October 2008) for the area, proved too much for the largest horizontal limb, which broke off close to the trunk. 

In May 2009 the tree grew a sparse cover of shoots and leaves to show there was still some life in it. The cattle were put out to graze in April, which may have spelled the end. 

The tree came crashing down as windblow some time in September or October 2009. From the direction it came down it was clear the cattle had helped it on its way. The National Trust removed most of the branches, leaving the uprooted stump in situ, cut about 3 m from the collar. A count of annual rings gave an age of around 250 years, which is what I had estimated. In early summer 2010, the cattle were laying around the remains of the tree looking mightily pleased with their handiwork.

A decade earlier, the National Trust had planted a new common ash near the ancient tree, hoping just maybe, in 2250 or thereabouts, somebody might come to muse about its long history. But that was before Chalara ash dieback.