Posts tagged ‘oak’
Afterlife tool and spoke
Winter ash gale bend and yield
Oak a merest nodGabriel Hemery
During the recent winter gales in England I was inspired to write a Haiku poem. The amazing flexibility of the ash Fraxinus excelsior tree means that its wood is widely used in tool handles, sporting goods such as hockey sticks, and in the spokes of wooden wheels. In this short film made amidst a woodland gale, an ash tree waves and yields by amazing degrees in the gusting wind. Nearby (just visible distant far left) a stoic English oak Quercus robur tree hardly moves.
Gabriel Hemery
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Wishing all my readers a very Happy Christmas
and
a fruitful New Year
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- Woodland edge and oak tree with hoar frost
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- Oak tree and river frost
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- Oak tree wearing a snow blanket
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- Oak leaves and hoar frost
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- oak log in snow
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- Frosty oak woodland in sun and shade
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- Snowy Oak woodland at dusk
Gabriel Hemery
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Walking my dog in an acorn shower
At this time of year our woodlands are spectacular; seemingly a palette containing every colour ranging from the oranges and russet browns of fallen oak leaves, the red of hawthorn berries, to psychedelic pinks in Spindle fruits. Observe closely and your senses can be entertained in other ways too. During a walk through a local woodland with my dog, I was enthralled by a percussion performance by a stand of oak trees .. it was raining acorns.
I recorded the acorn music – click on the play button above to listen.
Listen carefully and you will hear three gusts of wind; each appearing as a rising crescendo of rustling approaching through the woodland. With each gust the shower of acorns increases. I love the way that the falling acorns make three distinct sounds: crashing through the leaves of the canopy, tonking on the branches that sometime block their way, and thudding as they hit the ground. Some fall very close to my recording equipment too!
It seems that 2011 is a mast year for oak, at least in parts of southern Britain. Oak trees produce acorns every year but every four to seven years they produce an extra heavy crop. These are called mast years. There is still plenty of debate as to why trees behave in this way: it could be to do with water availability, temperature (in winter or spring), lack of frost during flowering or other reasons (see this scientific paper). We know that the extra effort put into producing so much seed can reduce the amount that a tree grows that year. Here is an interesting piece of work I came across, called dendromastecology, that provides evidence about the tradeoff between incremental tree growth and reproductive effort.
My walk left me wondering, along the lines of a popular saying, whether:
If an acorn falls in a forest,
And no-one is around to hear it,
Does it make a sound?
Gabriel Hemery
Cecidology – the study of galls produced on trees and plants by fungi, insects, or mites
Most children have played games with oak apples (e.g. they’re great in a slingshot!) but few kids, or adults, realise that an oak apple is not a natural part of the tree, at least not in a botanical sense. Oak apples are one example of a Gall and there are many hundreds of other types of galls found on trees. Galls are actually made by insects, or sometimes caused by fungi. Look carefully at an old oak apple and you will see a tiny hole where the wasp (e.g. Biorhiza pallida) exited the gall when ready to leave. Cut open a fresh oak apple and you will find the white larva or grub of the wasp nestling inside.
Certain insects that feed on trees can create their own mini-habitats on a plant to protect them during part of their reproductive cycle: we call these a gall. They manipulate the plant tissue to provide protection from predators and food. This year I’ve been on some cecidological forays through woodland near my home and found some interesting examples of galls.
Lime nail galls (Eriophyes tiliae) can be seen on lime trees in early summer and are appropriately named. They look like bright red nails that have been driven through the leaf from underneath.
Lime nail galls (Eriophyes tiliae) on large-leaved lime leaves following a rain storm in early summer
Perhaps my favourite gall is the Robin’s pincushion; a gall that forms on the dog rose. It is often seen in hedgerow or woodland edge. Its tangled mass of green and red growths can appear on stems and leaves.
Robin's pincushion gall (Diplolepis rosae) on Dog rose (Rosa canina)
There are many galls, other than the oak apple, that appear on various oak species. Some common oak gall species on pedunculate oak in Europe are the Artichoke gall and Spangle gall.
Oak artichoke gall (Andrcus fecundata) on stem and oak spangle galls (Neuroterus quercusbaccarum) on leaf underside of a pedunculate oak (Quercus robur)
I am certainly not a gall specialist or cecidologist but I find them fascinating. If you want to find out more I recommend a visit to the website of the British Plant Gall Society.
Gabriel Hemery
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High on the windswept and misty wild moorland of Dartmoor in south west England nestle three extreme oak woodlands. The most well-known is Wistman’s Wood, which has been the subject of numerous ecological studies. Less widely known are Black Tor Copse in the north of Dartmoor, and Piles Copse in the south.
Piles Copse oak woodland 2011. Click to enlarge.
I completed my Undergraduate dissertation studying the biogeography of Piles Copse. I realised that it was 20 years since this work and that I had not been back since. During a recent visit to Devon I made a return visit.
I set off for the short walk from the nearby village of Cornwood at dawn. Climbing first the domed mass of Stalldown Barrow, I followed the Bronze Age stonerow that leads to the summit. As is often the case with Dartmoor, visibility was very limited thanks to the famous mists (as a former member of the Dartmoor Mountain Rescue I have some great stories to tell!). The eerie silence was broken only by the “kew” of buzzard and “prkk-prkk” of raven until, as I descended the hill’s heather-clad Eastern flanks and over the distant babble of the River Erme, I began to hear woodland birds; so I knew that I was on target. Soon, Piles Copse appeared below the swirling mists.
Piles Copse
Britain has five high altitude oak woodlands: Birkrigg and Keskadale in Cumbria; and Black Tor Copse, Piles Copse and Wistmans’ Wood on Dartmoor in Devon. It is generally believed that these woodlands are relics of ancient woodland surviving the original clearance of the uplands by prehistoric man. The oak trees in Piles Copse are pedunculate oak (Quercus robur) and survive mainly due to the protection offered by the clitter: a slope strewn with granite boulders, some as large as family cars. These prevent access by the grazing sheep, cattle and ponies; and provide some micro-climatic shelter. The copse is a magical place: both trees and boulders are clad in bright green mosses and tree branches festooned with bearded lichens and polypody ferns.
Two tree records
I am running a long-term photomonitoring project of two trees at Piles Copse, first noted in a publication of 1922. Their location is in the north-east corner of the copse near a wall that runs up the hill:
N 050° 26’40″ W 003° 54’32″ (Ordnance Survey SX645622) altitude 323m.
Tree 1 - “An isolated tree, at the north-east corner of the wood … its girth is 49 in., and its height 28 ft., its trunk is somewhat over 7 ft. to the first branch.” Christy & Worth 1922.
The tree was first described in 1922 and then identified and photographed by a local naturalist, Molly Spooner, in 1965. I found the tree again for my study in 1990. It had lost half of its crown. Finding it again in 2011 I was pleased to see that the canopy was very full and the leaves healthy. Even the branch that had split sometime before my last visit was alive and thriving, although horizontal and resting on the ground.
Piles Copse Tree 1 - 1965, 1990 and 2011.
Tree 2 - “Hard by is another type, the girth 67 in., but the trunk rises little more than a foot from the ground and then branches into four, the largest branch having a girth of 36 in. The height is 29 ft. and the radial spread 20 ft. 4in.” Christy & Worth 1922.
The tree had already lost two of its four low branches in 1990 although they were still attached as deadwood. In 2011 both had disappeared completely and overall, the canopy was higher. Among other trees in the copse today it does not look extraordinary, and would unlikely to have been noticed by Christy & Worth in 1922 had it been in its present state.
Piles Copse Tree 2 - 1965, 1990 and 2011.
If you visit Piles Copse, and particularly if you find my two trees, I’d love to hear from you.
Gabriel Hemery
Further Reading
Christy, M. and Worth, R.H. (1922). The ancient dwarf oak woods of Dartmoor. Transactions of the Devonshire Association 54, 291-342.
Hemery, G.E. (1991). A study of a pendunculate oak woodland in a severe environment, Piles Copse, Dartmoor. Unpublished Undergraduate thesis. pp.55.
Simmons, I.G. (1965). The Dartmoor oak copses: observations and speculations. Fields Studies 2, 225-235. Download
