Meanwhile, in the woodland glade, deep under the beech trees, both types of pipistrelle are dominant, but Myotis bats are also flitting through. A distinctive low-amplitude signal identifies the brown long-eared bat (Plecotus auritus), and proves that these most delicately adapted hunters are passing under the canopy at 11:16. Claire had expected the long-eared species to appear in this habitat; despite its exotic appearance, it is not rare. This extravagantly outfitted bat may well roost in Lambridge Wood Barn at the edge of Grim’s Dyke Wood. The same site would suit a large, and much more uncommon, bat whose signal was identified at 8:40 the following evening: the serotine bat (Eptesicus serotinus), a species quite capable of demolishing the big nocturnal beetles that abound under the beeches.
We add them all up. Six different bat species are exploiting the insect life in Grim’s Dyke Wood, which must surely be a sign of a generally healthy environment. There may even be a seventh. Claire found one brief signal that might—possibly—have emanated from a snub-nosed, moth-hunting barbastelle (Barbastella barbastella), a protected species, and one of Britain’s rarest bats. I earnestly wish it to be in our wood, but I know well the emotion naturalists experience as “the pull of rarity.” It is always so tempting to recognise a more uncommon option. I must rein in my enthusiasm. Until we put up another monitor and get definite evidence from longer calls, the barbastelle bat is “unproven.”
3
June
Mothing
It is a warm evening when Andrew and Clare Padmore arrive at the wood with their moth traps. Their small generator powers a bright light set in the middle of a stage. Beneath this platform the moths that are attracted to the light can tumble down into a container full of papier-mâché eggboxes. The light goes on at dusk, and we sit under the beech trees on the edge of the large clearing waiting for darkness. Somewhere further away in the wood there is a noise made by some moderately large animal passing through; it is probably a badger somewhere near Grim’s Dyke. The night embraces us. The artificially illuminated beech trunks fade away a little spookily in the distance into far blackness.
The first moth—a beautiful Green Carpet Moth (Colostygia pectinataria)—comes out of the dark and desperately flutters around. It flops on to the ground sheet, and then off and around again until trapped in a jar where we can admire its triangular form and chequered green markings. As if from nowhere a big, hairy moth arrives. It has pale, furry legs which point forward as it rests, and exquisite, comb-like, brown antennae—Andrew identifies a Pale Tussock Moth (Calliteara pudibunda). It sits very still as if bemused, hind wings tucked under the forewings, which are marked with an impossibly complex, undulating greyish mottling. This particular species does not feed as an adult; its job is simply reproduction. Then comes a smaller, darker species, the Nut Tree Tussock (Colocasia coryli). “They are all,” says Andrew, “in the peak of condition, just emerged from the pupa.”
Feathered antennae distinguish most moths from butterflies, which have comparatively slender ones carrying knobs at the tips, and it is clear that our moths’ antennae are working away even now, twitching and sweeping. They are hypersensitive chemical sampling kits smelling out messages borne on the night air: odours from freshly unfurled leaves as food for their caterpillars, or the attractive pheromones that identify their mates. Theirs is an olfactory world; light is almost superfluous. I have a vision of the night air as a miasma, dense with molecular messages that only moths can read. They do however use the moon for navigation—our lights serve to confuse their direction-finding, which is why the insects arrive in our collecting boxes.
They are not alone: two fat, succulent cockchafer beetles—May bugs (Melontha melontha)—prove that other creatures are also abroad. The big brown beetles scrabble at the light, looking oddly like cockroaches with ill-fitting wings. There is something repellent about their insistence. Although their larvae cause damage to plant roots, the leaf-eating adults are harmless enough.
Now my eyes are fully accustomed to the darkness. The sky is visible in places between the interwoven crowns of the trees. It is not as profoundly dark as the distant recesses of the wood; it is rather an ineffably deep blue dotted with stars. As I look upwards, the lamplight catches on horizontally disposed beech branches, making drapes of them, a series of stacked canopies fading upwards. Our sampling site has become a kind of theatre, with beech trunks making the proscenium columns, framed by swags of real leaves. Two small bats now flutter into the auditorium, briefly picked out by the illumination: in and out, and then again. Will they scoff at the moths we have worked so hard to attract? When a Brimstone Moth (Opisthograptis luteolata) arrives, even I, a moth beginner, can identify it, since apart from a few reddish splashes on the front of the wings it is all brilliant sulphur yellow. In contrast, the Waved Umber Moth (Menophra abruptaria), the size of a small leaf, is so perfectly disguised it looks like a fragment of animated tree bark; at rest during the day it is invisible. New arrivals continue. The light attracts a kind of living fuzz of many other tiny insects I cannot identify. They all have secret livings to be made in the wood, if only I could know what they were. Somewhere in the distance a screech owl cries, but not so fiercely, as if in sympathy.
Andrew Padmore will return to the wood many times. More and more moth species will be attracted to his lure, which is later replaced by a solar-charged model hidden deep in the trees. No harm is done to the gentle moths: a photograph is taken and they are released to go about their business. As I write, the list of species recovered has now climbed beyond 150. Different moths are on the wing at different seasons, finishing perhaps with the November Moth. There is a curious poetry about moth names, which is an esoteric language of analogy, allusion and colour. The wood has yielded more than half a dozen different species of carpet moths. There are several pugs and rustics, thorns and swifts, footmen and oak beauties. Who can resist the Chinese Character, the Coxcomb Prominent or the Feathered Gothic? Or Bloomer’s Rivulet, the Rustic Shoulder Knot, Blood Vein and Mocha? They are all in the wood. Sometimes the common name is a simple description: the Blood Vein does indeed have a single, bloodily tinted vein describing a clear line like a gash across the middle of the wings. The Chinese Character does carry a distinctive pictogram; but it more closely resembles a bird-dropping when at rest. The Flounced Rustic is a furry, wonderfully complex, mottled and blotched mass of tans and greys; but I fail to see the flouncing. The Mocha is a nationally scarce buff-and-brown moth that maybe suggested coffee to some entomologist in the early days of the science. All the names have charm. Nobody could argue about the origin of Peach Blossom (Thyatira batis); it is marked as if some evolutionary leprechaun had implanted a few whole, pink flower heads on the darker forewings—just for fun.
We caught some moth species only once; they probably included wanderers from grasslands and gardens, feeding on plants that are not found in the wood. I would have loved to find more hawk moths, but we don’t have poplars or convolvulus to nourish their caterpillars. The moths most commonly trapped are naturally those whose food plants are present in Lambridge Wood. They are an intrinsic part of the ecology. The incomparable Peach Blossom is a bramble feeder, our commonest shrub. The most abundant species of all was trapped 111 times: the Clouded Magpie (Abraxas sylvata), a large and very pretty white moth blotched with patches of orange-brown, grey and black. Its food plant is wych elm, and Grim’s Dyke Wood has plenty of wych elms. Andrew had never realised that it could be so numerous—but then, elms are not so widespread these days. The Gold Swift (Phymatopus hecta) is one of the few insects that can feed on bracken, that potpourri of pernicious poisons, and does not have far to fly to find its favoured larval foodstuff. The little brown Snout Moth (Hypena proboscidalis), all pointy at the front and the shape of a tiny delta-wing aeroplane, needs nothing more than nettles. Despite its name, the Willow Beauty (Peribatodes rhomboidaria) can feed on tough ivy. This moth is a wonderful confection of brown and black speckles on a buff background—the very embodiment of the word “cryptic.” It
is so cryptically coloured the wonder is that the lepidopterists ever discovered it at all. The Satin Beauty (Deileptenia ribeata) is almost as well-disguised, and can feed on uncompromising yew needles. Then I must catalogue forty Lobster Moths (Stauropus fagi), dullish-coloured and almost as big as your thumb, and very plump and hirsute; as their Latin name implies, they favour Fagus, and there are beech trees as far as the eye can see.
The Lobster Moth reminds me of an interesting puzzle. In spite of the wealth of its lepidopteran life, I have noticed very few caterpillars since I have owned the wood. I have to conclude that this “eating machine” stage of the moth’s life takes special trouble not to be observed: a green body on green foliage, stick-like mimicry, rolling a leaf into a private self-service restaurant—these are some of the tricks of the larval trade that different species employ to avoid a questing beak. Only very poisonous species like to announce themselves in yellow and black stripes. On a hazel stick I did find the caterpillar of a member of the geometer family (it might even have been that of the Brimstone Moth), a typical “inchworm” with legs only fore and aft along the body, so it progresses by looping up its midriff as it brings its hind legs forward. Measured steps are not an inaccurate description (hence the geometry). When it stops under the threat of my close eye, it raises one end into the air and becomes a twig. Even more, it shows countershading. That is, its upper part is darker than its underside. Normally, things lit from above are relatively illumined on that side, which makes them more conspicuous. By introducing compensating darker tones on the dorsal part of the body, such contrasts are flattened out: the object (well, inchworm) melts into the background. As they say on soap powder advertisements: it really works!
As for the Lobster Moth, high in our beech canopy, it is a deceiver to dumbfound John le Carré. When the larva first hatches from the egg it is an ant imitator, with spindly legs that wave around a lot, and it thrashes about like an injured ant if it is disturbed. The young caterpillars are reported to defend their egg territory, and will drive off any rival caterpillar that comes too close. As they moult and grow, they become both voracious leaf consumers and very odd looking—one of nature’s gargoyles. The head is larger and the legs behind it (the thoracic legs of the adult) become unnaturally attenuated even as the four pairs of legs further behind become stumpy and grasping. The back gets covered in humps, and the tail end can turn back on itself like some kind of turgid bladder, all finished off with a spike. The entire caterpillar develops a shade of pinky brown, and since it can be seventy millimetres long fully grown, it is quite enough to give a shock to any casual stroller who comes across one; especially when its body is raised in the threat position with the head arched back. It is said to resemble a cooked lobster; it is certainly scary.
I wonder if all of our 150 or so moths have such complex tales to tell. The beech canopy is humming with life stories, the brambles alive with deceptions and role-playing, each crack in the bark of every tree a dark dive hiding darker narratives.
Beech
By June, the beech canopy has garnered all the light, each leaf second-guessing its neighbour at grasping any space giving on to the sky. The taller trees soar upwards for more than a hundred feet. From the ground they seem all trunk, but from the sky they seem all crown. The beech (Fagus sylvatica) has always been a working tree: for furniture, fire and faggots. John Evelyn’s Sylva, the first book published by the Royal Society in 1664, and the founding text of forestry, said of beech trees: “they will grow to a stupendous procerity, though the soil be stony and very barren: Also upon the declivities, sides, and tops of high hills, and chalky mountains especially.” Evelyn then quotes an old rhyme:
Beech made their chests, their beds and the joyn’d-stools,
Beech made the board, the platters, and the bowls.
Three hundred years ago, beech may not have built the houses, but it did almost everything else. The management of beech trees has been the story of our wood for centuries.
In 1748, Peter Kalm, a Finnish protégé of the great Swedish botanist Linnaeus (who named the beech tree scientifically), made an informed journey through the woodlands of England.1 He observed the Chiltern lands at Little Gaddesden, a short distance from our wood over the Buckinghamshire border. Some of the trees he saw might indeed have been our own, for “the beeches are for many fathoms in their lower part entirely without branches, and quite smooth.” The woodsmen climbed the trees in search of squirrels (at that time red squirrels), or rooks’ nests to provide the table with squabs. They rarely used ladders; instead they strapped hideously sharp “crampoons” to their feet to scale the trees, like some oversized squirrel themselves.
Kalm recorded precisely how, after felling, every part of the tree had a value; almost nothing went to waste. Farmers used to say of pigs that everything is used except the squeak; the beech woodsmen’s equivalent might be: everything has a use except the bark. They
sold the smooth part, or sawn it up into boards, but those of which the stem had been knotty or uneven was cut up for firewood and piled up in cords. When the beeches…were cut down and felled to the ground they were cut off close to the earth. Two or three years after that, the stump that had been left, together with all the roots proceeding from it…was dug up, cut into small pieces and arranged in four sided oblong heaps to dry…In digging up the roots they had been so careful that among those heaps there lay a great many fibres of the roots, whose length was not over 6 inches, and thickness not greater than a quill pen. These roots thus arranged were sold as fuel to those who lived some English miles around.
Dry twigs bound into bundles of faggots were fuel for bread ovens. Some observers even regarded the beeches in the way that we now look at factory farming. The pioneering landscape architect Humphrey Repton remarked in 1803 that “these woods are evidently considered rather as objects of profit than of picturesque beauty.” He preferred specimen trees carrying full crowns of branches adorning a grand park, the whole designed for effect. He would not have stooped to grub up roots.
Kalm also made calculations, and his observations show a clear, scientific mind at work. “A beech trunk was measured which had at the large end fifty four sap rings. The diameter was just two feet. The sap rings which were found nearest the heart were narrowest and smallest, from which they grew larger the further they lay from the heart out towards the surface.” A cross-section cut from the trunk of a tree could not have been better described. The “sap rings” are the record of the new wood lain down by each year’s growth beneath the bark: fifty-four rings is fifty-four years, the age of the tree. Our own wood needs just such a chronology.
The neighbouring wood has had some recent felling, and I can record the cleanly cut log-ends on display in a stack by the entrance to Grim’s Dyke Wood. Beech chronology turns out to be not quite as simple to measure as I might have thought. The good thing about our trees is that such straight trunks provide a reliable, nearly circular section. Nearer the ground the trunks are all buttressed and irregular, and no two diameters are the same; these undulations record the profiles of the “props” that hold the trunks aloft. So the upper part of the tree—waist-height and above—provides the best experiment. Since all tree trunks do taper gently, different sections of the same tree will have decreasing diameter upwards. The difficulty is that the “narrowest and smallest” rings in the centre of the tree are not so easy to read. Some years added no more than a millimetre of new wood.
Stacked beech trunks displaying growth rings.
I have to take a felled piece of heartwood home to see if I can tease out some figures. I laboriously buff it with fine sandpaper for hours, and as the distracting irregularities are polished away, so the early growth rings become clearer as darker lines. It is like seeing a diagnostic thumbprint slowly developing from obscurity. The wood almost shines pink-brown when I finally make out twenty-seven rings in thirty-five millimetres diameter. It evidently took a long time for this particular tree to get going, after which it sp
ed up mightily. Even in the mature part of the tree not every ring announces itself clearly. There are good years and bad: the summers of 1974 and 1975 were droughts, and the growth rings would have been minimal. Skilled dendrochronologists can “read” tree rings as a diary of climatic variation extending over centuries, but my skills do not extend that far. However, in older trees most of the rings add about three to four millimetres to the radius every year, and these can be counted easily enough. I eventually reach a consensus with my own scientific conscience. Several trees come out with eighty rings, more or less, possibly as many as eighty-five. Jackie provides a second pair of unbiased and independent eyes and tots up a similar figure. These are from trunks ranging in diameter from twenty-seven to fifty centimetres; and another trunk of forty-three-centimetre diameter has just under sixty rings. I cannot prove that the former come from higher in a tree that might have had a more impressive base. What I can say, with confidence, is that a number of beeches in Lambridge Wood grew from seedlings around 1930, and are now fine, big trees.
It is easy enough to convert diameters into circumferences, and with my very own trees the latter is what I record at shoulder-height with my tape measure. I can prove that many of the standing beeches are of similar size to those sitting on the log pile. It is actually rather easy to show this without wielding the tape, by using that alternative, hippy measurement—“the hug.” Trees with a fifty-centimetre diameter can be comfortably hugged, with hands meeting around their girth. There are an equal number of trees that are just too big to hug, although they do decrease in diameter to become huggable towards the canopy. And then there are the real giant trees, like the King Tree and the Queen Tree, and one I call the Elephant, with circumferences up to 250 centimetres. Surely these are much older than eighty years. If I assume that they continue to grow by adding a three-to-four-millimetre ring every year, it is not unreasonable to arrive at an age of 140 to 180 years. There are perhaps a dozen of these trees scattered through our wood. Their bark eventually loses the smoothness of the younger trees to become lightly scarred, as if daubed with vertical stretch-marks. Since there are certainly no trees still more antique, I conclude that these fine examples have been responsible for seeding some of their younger companions. They have been left alone. A great felling must have occurred about eighty years ago—and selective felling probably continued for another twenty years or so, until Sir Thomas Barlow’s ownership, when we know that little happened in our part of the wood. The somewhat “unhuggables” may well record regrowth after another, earlier phase of beech harvesting. There is no doubt at all that the whole wood has been replaced, thinned, sawn and regenerated. Its history is written in the tree rings. This is the same wood that John Stuart Mill walked through in 1828. Only the trees have changed.
The Wood for the Trees Page 7
