Daniel Greenwood

The language of leaves

Posts tagged ‘Oaks of London’

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This is an expanded version of an article published in the winter 2017-18 edition of London Wildlife Trust‘s Wild London magazine

As autumn draws to a close, the bare branches of trees stark against wintry skies, we find ourselves on the tail-end of a mast year for London’s acorns. Mast is another name for nuts or seeds, with beech nuts often referred to as ‘beech-mast’. It means a time when the weather and temperatures in spring and summer have created the right conditions for a bumper crop.

Oaks are wind-pollinated, one of nature’s first reproductive mechanisms for plants that evolved very early on land with the arrival of spore-bearing mosses hundreds of millions of years ago. Trees like cherry and others in the rose family, are pollinated by bees, butterflies, moths and flies.

Though cherries are far tastier than acorns, the oak’s fruit is one of the most important to us for several reasons. When acorns fall many of them will simply fail in the leaf litter or decay away to feed the soil. Birds like jays will stash acorns and plant thousands of them to keep them alive over the winter. Grey squirrels do exactly the same.

If you think about it, and scientists have been, this is one of the most important vehicles for woodland creation on Earth. It’s also one of the reasons that oak woods were able to recolonise the Northern Hemisphere after the end of the last glacial period some 12-14,000 years ago.

If any of those jays died or forgot some of their acorns, they sprouted into trees and woods, many of which would eventually form great woody landscapes adapted and exploited to what we now know as the Great North Wood, Epping Forest, the Weald and the New Forest.

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Oak mast

In North America there were entire cultures of Native Americans who built their lifestyles on a diet of acorns. Beneath their shells acorns are nuts that can be ground down for flour, coffee or even jelly.

In Britain the hazelnut is one of the single most important food sources for our species, especially before the advent of farming when hunter gatherers relied on foraging to survive. Archaeologists have found regular evidence of hazel nut shells at prehistoric settlement sites, sometimes in vast numbers. There is also evidence that our ancestors cooked hazel into a paste that could be taken on long journeys.

But perhaps the most fascinating cultural impact of the acorn is when it is missing, and in its place a parasite. In the spring tiny parasitic wasps appear from galls, a growth (sometimes referred to as a tumour) that has prospered in the place of an acorn, and lay their own eggs in an acorn bud. A chemical reaction takes place in the tissue of the plant and a gall is formed.

There are many species of gall, and many of them are not instigated by solitary wasps, but one of the most significant for human civilisation is that of the oak apple gall.

The oak apple gall was imported to Britain over a 1000 years ago for its prime use in the creation of ink. The galls can be ground down and mixed with chemicals to make a black ink. It was this ink that was used to write almost all of the major doctrines and political agreements in the western world.

The Magna Carta and the American Declaration of Independence are but two of them and, indeed, that sylvan scripture known as the Forest Charter of 1217 will also have been transcribed in oak ink. Amazingly, it was only in the 1970s that the German government stopped using oak gall ink for use in all official documentation.

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Knopper galls in summer

London’s other notable seeds are those of horse chestnut, beech and sweet chestnut. Horse chestnuts, named after the horseshoe-shape at the base of the leaf stem or petiole when plucked from a branch, are not related to sweet chestnuts. Neither of these trees are deemed native to the United Kingdom, and sweet chestnut sits in with the oaks in the beech family.

If you roasted chestnuts on an open fire at Christmas it will be those of the sweet, not the horse chestnut. Sweet chestnuts are the fruit found inside painfully spikey shells, very similar to the horse chestnut.

For the more childish among us, the horse chestnut is really known as the conker tree. The sight of a glossy brown conker in roadside leaf piles in autumn is a thing of wonder. The maple family’s seeds may not be palatable, but the game of ‘helicopters’ was one of great pleasure for school children before the arrival of smartphones.

Though we often focus on the edibility of plants and their fruit and seeds, the crops of trees like rowan, oak and beech have an impact on the activity and behaviour of birds in autumn. In October there can be seen large movements of jays, with birds acting quickly to secure seeds and plant them in a suitable location.

A jay massaging its way high across an open field, heading to and from an oak or beech wood, is a common sight in the early autumn. Redwing, a winter arrival in the UK, rely on rowan’s bright red fruit. Changes in the Scandinavian crop can trigger the movements of this species south as winter draws in.

Where old, fruit-packed hedgerows still exist in the UK, heavy with rosehips, haws and holly berries, redwings can be found feasting. From places as far apart as rural moorland and urban London, their distinctive but subtle tseep calls can be heard overhead at night.

Those nocturnal calls can be a pleasant reminder of the changing season, of the fundamental need for fruit and seed for the wild and civilised alike.

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Bexley oaks - March 2017 djg-4

This is an update on my Oaks of London photography series. The photos have been taken with DSLRs, compact cameras and my phone camera. Rather than trying to put together a glossy array of ancient oak photos, I want to draw attention to the unseen trees fighting it out with modern London, many of which are teetering on the margins. Lack of funding to protect and manage London’s oaks is biting, as is a lack of understanding and appreciation of their heritage and wildlife value. These trees have stories to tell.

Photographing the oaks of London is a fairly impossible but very slow and enjoyable project. South-east London is, quite literally, a walk in the park. Such is the extent of green space south of the river that there are many oaks to be found and some very closely concentrated, especially in Dulwich or Honor Oak, which I covered last year. But moving into new areas can be tricky, London’s oaks are on the margins now, they no longer form the central, spiritual role of Celtic or event recent times, when gospel oaks held prominence in settlements or when the Druids (the knowers of oak) made sacrifices before them, something I am not suggesting we bring back in 2017. One of the things I’ve learned this year, also after having read some of Aljos Farjon’s new book Ancient Oaks in the English Landscape, is that old parks and estates are key to the survival of oaks.

In March 2017 as part of a walk with London Wildlife Trust, we were led by Mathew Frith around Danson Park and Bexley Woods. Two oaks stood out in this walk, an area I would not have known about without the connections I have with the Trust and exposure to knowledge of people like Mathew. One oak, the Bexley Charter Oak, can be found in TimeOut’s The Great Trees of London, and it has a lovely fence around it protecting its root plate. The tree is some 200 years old and reflects the treatment that all these oaks deserve to have, if they stand in similar surroundings.

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Another oak is not faring so well and is not treated with the same level of affection, or perhaps simply a different kind. Walking through Bexley Woods and following the river Shuttle east brings you to an oak quite unlike one I’ve seen.

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The oak is entirely hollowed out until about human waist-height, with charred sapwood that shows it has had fires lit inside. It is a stunning tree, wild and exposed on the edge of the river and a footpath. It is a symbol of London’s oaks on the edge: unprotected, vandalised but fighting on. The tree still lives. In many ways the actions here of what you can only expect to have been children or ‘wayward’ teens, is a process of veteranisation. The only difference is that rather than being undertaken by arboriculturalists, it’s the unintended work of the public.

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Shifting south-west to the boundary of Lewisham and Bromley is Beckenham Place Park. This old country estate, fit with a mansion house very similar in style to that of Danson Park, has open parkland and many fine veteran trees. On the hill is a remnant of the Great North Wood, the typical oak-hornbeam and hazel mixture that can be found in chunks all the way up to Dulwich. Thanks to Lucy Mitchell for showing me round.

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The oak featured here is a lapsed pollard, meaning that it was likely once cut back higher up but has, like many old oak and beech trees across London, been left to restructure itself. This oak is somewhere between the two Bexley oaks mentioned above. It needs the care of the Bexley Charter Oak as it is experiencing stress and strain from its exposure to footfall. Looking closely at the buttresses you could see that dogs had been digging holes, pooing on the roots, and that the collective trampling was exposing roots in some places. It’s a tree you just want to hug and climb, but its spot right there in front of the house leaves it open to quiet, unintended harm.

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Oaks of London Flickr photos
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Clapham Common - 27-3-17 blog-3

This English oak is easily missed, to the point where I didn’t notice it was an oak until looking at the photo later. This early spring sunshine is the kind that brings people to sit underneath trees, like the man in the distance on Clapham Common. His bike is resting against the trunk behind him.

Oaks of London

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Enfield oak

This English oak (Quercus robur) is alongside the Great Cambridge Road near Turkey Street station in Enfield, north London. It was photographed on my phone in January 2017. It stands in what evidently was once a more open, rural landscape. It’s a big, healthy-looking tree, likely between 200 and 300 years old. What I like about this one is the clash of the old and the new, rural and urban. If it can remain in peace it could live a good many centuries. This is dependent also on a gradual reduction in emissions from the nearby traffic as predicted move towards electric vehicles progresses and its ability to remain unimpeded by either self-seeded trees or new plantings. If this landscape was abandoned in future, the oak would create a new woodland of oaks around it.

Oaks of London

 

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Richmond Park is a National Nature Reserve managed by the Royal Parks. It’s home to an absurd array of veteran and ancient oaks. Some of the older trees show clear evidence of pollarding, but no sign of anything recent. It was a wet and windy day in south-west London, your camera equipment has to be as tough as oak to stick it out for long in these conditions. I’ve overexposed some of the images as it was so dark and dreary, and oak doesn’t burst with colour in winter. The park itself is a shock to find, a vast expanse somewhat pegged back by the constant chunter of traffic passing through.

Oaks of London archive

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Tree: Old common boundary of Hounslow Heath, Hounslow, west London, November 2016
Species: English oak, Quercus robur
Age: Between 200-300 years?
Status: Under attack

This phone photo was all I could take at the time of this sprawling specimen, so let’s consider it a sketch. It was on the western edge of Hounslow Heath in west London. I know less about west London’s natural history than the south, though I am familiar with the Crane valley. This oak is probably a coppice or a felled, accidental coppice, which has regrown. It is well-climbed but showed signs of charring from fire at the base. Gorse nearby had been burnt in what are considered arson attacks. In many ways the fact this tree is not older and more cavernous and has fewer points of entry for fire may protect it. Hopefully the arsonists – common in urban nature reserves – grow out of it or else are prosecuted.

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Trees: Old field boundaries of Dulwich Park, Southwark, London, September 2016
Species: English oak, Quercus robur
Age: Between 200-500 years?
Status: Fair

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This sizeable boundary oak lost a limb in a recent storm but it should be able to recover. It’s important to remember that many ancient trees lose their heartwood through storm damage, lightning strikes or by other means. It is also very pleasing to see that the fallen limb has been left to decay next to the tree. Southwark Council are generally good at doing this where conservation policies make it to grounds maintenance.

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One of the more intriguing trees is this heavily belted pollard oak. I like to call it the toilet oak. It has put on a lot of bulgewood over the centuries as it’s had to reach out to the light. My images are slightly distorted by the 10-24mm wide angle lens I use, seen in the lean of the toilet block. It seems in fair condition despite the erosion around its base, likely from the soles of children’s shoes as they climb it.

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In the fenced nature reserve area is a neat line of former field boundary oaks from the time of farmland smallholdings, likely dating further back to when this was Dulwich Common. These oaks also show a great deal of bulgewood from the interal shifting of the tree’s woody fibres as it has reached out towards the light. They once grew in full sunlight, undeterred.

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The one nearest the gate has all the signs of recovering from lost limbs, epicormic growth and the need to put on bulgewood. Immediate trouble for this tree is coming from the yew growing on the right hand side.

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It’s an impressive pollard, probably about 300 years old. It is reaching for the light outside the nature reserve.

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The furthest oak has lost one of its limbs and has a large wound in the heart of the tree. I can’t underline enough how important this is as a habitat feature for the fungi and invertebrates. It is a major wound but it should be able to recover over time now that the excess weight has been lost.

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The largest of the oaks is this fine one next to the boating lake. I remember this well from childhood (decades not centuries). It has fairly complete leaf cover, so few signs of stress despite its closeness to the path and amenities.

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The trunk shows the bulge of a former limb, the buttresses at the base holding the tree steady. When I photographed the oak it had been marked by the business card of a commercial dog walker.

Oaks of London archive
I’m leading a tree walk at Dulwich Park on Saturday 29th October 2016 
Dulwich Society
Dulwich Park Friends
My oaks of London gallery on Flickr

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Tree: The Beulah Spa oak, Croydon, London, October 2016
Species: English oak, Quercus robur
Age: Between 300-600 years
Status: Good

Next up on my slow-motion journey through the oaks of London is another of the Great North Wood oaks. This was shown to me by Jo Wright and Sam Bentley-Toon.

This oak is a confusing one. At first sight it appears to be an ancient pollard, possibly 500-600 years of age. Closer examination shows that it may actually be a coppice or regrown fell, meaning it’s more like 300 years old at most. Oliver Rackham pointed out that coppiced oaks can look like pollards in the way other species would appear to be pollarded.

It’s situated in Spa Wood (or the Lawns) in South Norwood. It is certainly a remnant of the Beulah Spa, created in the 1840s before the opening of the Crystal Palace. Therefore it is another Great North Wood oak.

Links: History of the Beulah Spa – Norwood Society

 

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OTH oaks-5

This post is part of my oaks of London project

For the past five years I have been searching hedge lines, woods, parks and boundaries for the undulating mass of an old oak. This search has not taken place in the English countryside, instead the border of the London boroughs of Southwark and Lewisham. The southern towns of Southwark were once the parish of Camberwell and its boundary with Lewisham still supports centuries-old oak trees that were the previous markers between old Camberwell and Lewisham. Along with the Dulwich Woods and One Tree Hill, these trees are the strongest ties to the much diminished Great North Wood.

 

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One Tree Hill (centre left) when it was ancient woodland in 1799

The Great North Wood

The Great North Wood was a landscape of woods and commons that stretched from Selhurst to Deptford. It was worked over centuries for its timber and underwood (sessile oak, hornbeam and hazel, mainly) for ship building, tannin extraction and charcoal burning. Its origins are in the wildwoods that spread after the end of the last glacial period 10-12,000 years ago at the start of the Holocene. The oaks remain where other species have disappeared as they are tough, long-living (sometimes 800 years in open land) and are of great use to our species. The Forestry Commission approximates that London’s trees are worth £43billion in their environmental and amenity value. Oaks are some of the most important. Their carbon storage capabilities should be remembered by those controlling planting regimes in cities today.

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This old image (likely early 1900s) shows what One Tree Hill’s western slopes were like. The earlier map, dated 1799, shows that One Tree Hill was an isolated ancient woodland. It once connected with the Dulwich Woods which skirt the left hand side of that image, and spread even further before humans began managing the woods. That could have been thousands of years ago, however. The Dulwich Woods are very likely several thousand years old.  There is no woodland at all but plenty of shrubs, likely including gorse and hawthorn. The landscape swelling into Lewisham shows much of south London’s old landscape was farmland. The boundaries of the farms were marked by old oaks.

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Pollarding

One of the first mistakes made by those (myself included, of course) looking for old trees in the landscape is to head for woodland first. The oldest trees are usually living in isolation in what has longest been open land. The great Oliver Rackham told us that ‘ancient woods are not the place to look for ancient trees’. The best trick is really to get an old map, compare it with a current one and see if there are any clear boundaries where trees may have been planted or perhaps wild trees maintained as standards. Sometimes the old maps show trees dotted along the edges. The image above is a pollarded English oak (Quercus robur) at the entrance to One Tree Hill on Honor Oak Park. The tree is actually in the grounds of the Honor Oak Allotments and a line of similarly old oaks can be found running up alongside it.

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This oak, one down from the previous, has clearly been pollarded (c.1900s) and is now swamped by other trees. Logic says that pollarding it again and removing some of the surrounding growth would allow the trees to re-balance and go on living indefinitely, but experimental pollarding taking place in Epping Forest suggests otherwise. Lapsed beech pollards are known to die when pollarded again. These oaks may be so unused to management that pollarding them will kill them off. We may have to accept that these landmarks of the Great North Wood have a limited time left.

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The Oak(s) of Honor

One Tree Hill is a good case study for remnant Great North Wood sites as it was open land until the mid-20th century but was woodland on the north-western slopes up until the 1840s. Today it is returning to woodland having been largely managed through non-intervention, bar access works and hedge planting, by the Friends of One Tree Hill and Southwark Council.

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One Tree Hill gets its name from the single English oak (pictured) which was replanted in 1905 when the hill was reopened to the public after a battle to save it from becoming a golf course. 15,000 people conducted a mass trespass on 10th October 1897 to challenge the Honor Oak & Forest Hill golf club’s attempts to fence and enclose the hill.

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The previous Oak of Honor was thought to be much older and was a boundary tree for the old vice-counties of Kent and Surrey. It was also the edge of the Honour of Gloucester’s land. The idea is that in 1602 Queen Elizabeth sat under the tree and was thus honoured thereafter. Today the Oak of Honor is the most obvious tree to seek but by no means the oldest. I love that it has so influenced local place names. An old black and white photograph of the former oak (the church building can just be seen in the top right) gives the sense that the oak was not so old, perhaps only a few hundred years before it perished. This tree was destroyed by lightning in 1888.

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To the right is the oak of Honor when it was only a decade old. The open landscape of early 20th century Honor Oak/Forest Hill is filling up with housing. The tree cover on the hill was largely hawthorn scrub, as can be seen behind the caged oak.

Wildlife

It’s worth remembering that though we are fixated by neat and tidy trees in urban areas, often for safety reasons, that oaks provide habitat for a great number of species. The Oak of Honor in September 2015 held many knopper galls, the protective case for a gall wasp (Andrus quercuscalicis), and oak apple galls.

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The top of One Tree Hill is an excellent spot to find butterflies in spring and summer because it is open and sunny. This speckled wood (Parage aegaria), one of the contemporary Great North Wood’s most common butterflies, was enjoying some September sunshine on the great tree’s leaves.

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The winter months provide ample opportunity to find nuthatch (Sitta europaea) which is often tied to oaks because of the invertebrates it forages from the bark and the old woodpecker holes it nests in. It makes a neat mud ring around woodpecker holes to make the entrance smaller and more protective for its young.

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The purple hairstreak was the first ecological record at One Tree Hill when it was mentioned for the first time in the 1766 publication The Aurelian by Moses Harris. This overlooked butterfly was ‘commonly taken in plenty in Oak-of-Honour Wood, near Peckham, Surry.’ It’s one of the insects promoted by conservation groups in the Great North Wood, a good indicator of long-term woodland cover, especially at nearby Sydenham Hill and Dulwich Woods. The purple hairstreak is only usually seen by those straining to look up at the canopy or those lucky enough to stumble across one when it’s down and dazed on the path.

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Secret oaks

The oldest of One Tree Hill’s oaks is likely to be this lapsed pollard (whereby a tree is cut higher up – coppice is cut at the base – to prevent grazing animals eating regrowth) growing on the path that runs adjacent to Brenchley Gardens. I’ve seen a photograph somewhere of the tree isolated in open land, with Peckham’s farms rolling down to what is now Peckham Common.

OTH pollards-1 The tree, seen here on the right of the photograph (its lean exaggerated by the distortion of my 10-24mm wide angle lens) is competing with the seedlings that have likely fallen or been stashed by grey squirrels (Sciurus carolinensis) and members of the corvid family, especially jays (Garrulous glandarius). You could suggest that the new woods of One Tree Hill are products of its old boundary oaks, where the dominant species is oak. Recent research has uncovered how important crows are in establishing new oak woods across the northern hemisphere.

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One of the lower limbs is rotting nicely and providing habitat for slime moulds and small mushrooms, whether this is a bonnet (Mycena) or a parachute (Marasmius), I couldn’t tell you. The life that old oaks can support adds to the tree’s immense amenity and ecological value. Oaks typify the anthropomorphic but no less accurate notion of trees being ‘accommodating’ to many species.

Next door to One Tree Hill and its allotments is Camberwell New Cemetery, a more authentic remnant of Honor Oak’s open landscape of the past 200 years. One boundary, otherwise planted with Lombardy poplar (Populus nigra ‘Italica’), has two old English oaks. One has been hollowed out, possibly after being struck by lightning or affected by human damage. It’s an example of trees as habitat, something which people are generally uncomfortable with at first, especially with fungi as they think the tree is dying. In August 2015 the hollowed oak had the fruiting body of what I think was chicken-of-the-woods (Laetiporus sulphurous). Oak supports many insects and also fungus. The oldest oaks you are likely to find will be dependent to some degree on mycorrhizal relationships with fungi. Fungi can also help the oaks by removing bits of deadwood that may otherwise add extra weight to the tree as it ages. Some species are necrophratic and will eventually kill a tree because they ‘take more than they give’.

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On first thought I was suspicious that the two oaks seen here might be the same two on the allotment-cemetery boundary. This is a photo from the 1920s that shows Camberwell New Cemetery and the Honor Oak Recreation Ground as open land being grazed by a flock of sheep. Evidently the sheep were used to keep the grass short for golf, or maybe also as a way to support a local farmer. The golf club house can be seen in the distance. The building on the hill in the distance is St. Augustine’s Church (1872-3). These two trees are too far away to be the same as those above, they are probably instead some of the black lines that can be seen in the distance. Note also the absence of any tree cover on One Tree Hill beneath and to the right of the church. Between the mid-1800s and this point, there ancient woodland had been well and truly grubbed out, possibly even some old boundary trees going as well. Today, this would be unacceptable.

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Instead, I think this image of the old golf club house exhibits the line of oaks. These oaks look to be dying back, possibly because of the impact of building the club house where the trees’ roots were. The distance between St. Augustine’s and the line of trees is one parcel closer than the previous image (Steve Grindlay).

 

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