A longer, yellower and altogether thinner centipede, much more generously endowed with up to eighty-five pairs of legs (Stigmatogaster subterranea), moves more slowly when disturbed under the log, and bends itself into elegant curves as it negotiates its escape, like a self-twisting rope. Slender, flexible and active, Geophilus species possess limbs that tot up somewhere between the fifteen or so pairs of the brown centipedes (Lithobius) and the numerous ones of Stigmatogaster; and finally there is small and elegant Cryptops hortensis, a species related to giant and very poisonous centipedes from South America. What none of these centipedes has is the “hundred legs” promised by their common name. They always have an odd number of pairs of legs, matching the number of rings into which their bodies are segmented. Each species must have a favourite prey and favourite schemes for hunting them, but we will not know the details until we can learn to see intimately into their secret, blacked-out world.
Still subtler ploys are played out where no eyes can follow. Fungal hyphae—the living threads of the organism—quest through dead beech wood in search of nourishment, but dead wood lacks nitrogen compounds that help the fungus grow. Within rotten wood also live many kinds of tiny nematode worms. I often come across them under the microscope thrashing about in their death throes—tiny, all-but-transparent tapering sausages, which simply cannot be identified without sophisticated modern molecular techniques.9 These little worms do contain useful quantities of nitrogen. Fungi have evolved techniques for capturing and consuming unfortunate worms by spinning lasso traps with their hyphal threads: the traps tighten on the tiny worms as they pass. Sucking on the dead bodies, the fungus can now break down yet more wood with renewed vigour, bolstered with a nitrogenous “fix”: murder in the dark.
Woodlice eat wood. They are not insects, as a casual observer might assume. In fact they are crustaceans, second cousins to shrimps and crabs. They are also called slaters. Their close relatives (marine isopods) live in the sea, and some of the bigger ones look a little like my own favourite animals—the extinct trilobites—although the resemblance is superficial. Uniquely among crustaceans, woodlice have been abundantly successful in their colonisation of land. Nobody has much to say against them—they are not like bedbugs—but they are not particularly endearing either. No bestselling children’s author has published “Willie the Woodlouse” or “Susie the Slater” books. Munching on wood is not a very glamorous option. There are five common species, and all of them are present in our wood, skulking under rotting logs, milling about on their fourteen pairs of legs. They do an extraordinarily important job in processing fallen organic material: their droppings make up an important part of “frass,” a mass of minute pellets that provide a kind of compost on which bacteria thrive, and are all part of returning hard, intractable wood to the soil. Under my lens I spot tiny white woodlice, and they are indeed their babies. Fertilised eggs are carried under the mother’s body until they hatch into miniature woodlice all ready to go. Woodlice are nothing less than self-perpetuating reprocessing machines.
Millipedes are mostly longer, slender vegetarians, and might be mistaken for centipedes until you see that each walking segment of the long body carries not one, but two pairs of legs; and no, they do not have a thousand pairs of legs, any more than the centipede has a hundred—although the world record of 750 pairs on a Californian species was set as recently as 2012. Millipedes amble slowly along, in no hurry. The commonest of our species is a woodland inhabitant everywhere (Cylindroiulus punctatus) that looks like many another of those purposeful many-legged perambulators, and its common name—blunt-tailed snake millipede—does not help much to pin down its identity. Four other species are in Grim’s Dyke Wood. One of them, the pill millipede (Glomeris marginata), rolls up for protection into a tight black shiny ball the size of a large pea, its segments interlocking until the head and tail come together. When I first saw one of these little spheres, I wondered if it were some kind of strange seed, until it unrolled and walked away. Many of my trilobites could pull off the same trick, and probably for the same reason, providing another wonderful example of convergent evolution, like the ghost orchid and the Dutchman’s pipe (this page). Another millipede, Chordeuma proximum, was something of a “find,” a westerly species making a rare appearance in the eastern part of England. Flat-backed millipedes (Polydesmus) look as if they were assembled from some kind of kit that clicks together to make miniature armoured trains trundling along at a regular pace. Dashing black carabid ground beetles, or the fat, three-legged toad that lives in the woodpile, might find them to their taste.
A list of animals and fungi could become tiresome, but is necessary to grasp the true richness of nature. Think of it as not so much an inventory as a catalogue leading to compelling and interlocking stories. The world beneath the rotting log is a small one, but it is marvellously complete. The cascade of life there comes ultimately from the sun. The photosynthetic work of a tree eats up the energy from sunshine for many years; as soon as the tree falls to the ground, the construction begins to unwind. Fungi play the vital role. A beech log left behind from cousin John’s felling is already dotted with hard brown spheres of Hypoxylon fragiforme (“beech woodwart”), a pioneer species that will be followed by a succession of others. I shall be looking for oyster mushrooms there next year. Beneath the log in the damp, dark places, the recyclers and degraders get to work. Different fungi from those on the exposed wood form their subtle patches, and their mycelium buckles down to unlock the energy stored in the wood. Worms tug organic matter down into the soil. Wood-eaters, and grazers of fungal patches, and then their predators, set up a food chain that is a lightless version, a dark parody, of the grass-herbivore-carnivore system that thrives in light and rain. Rot is creation in the underworld. That list, that catalogue,10 is the dramatis personae of a kind of soap opera of slow decomposition, where sex and death, voracity and subterfuge, play out their measured parts in the life habits of dozens of species “hidden away privily.”
I notice a pile of nibbled fruit stones (“pits”), no bigger than small peas. They are bleached white; at least twenty of them in what must have been a secret hideaway before I moved the log. For a few seconds I mistook them for rabbit pellets. They are surely from the wild cherry trees that grow nearby, and every one has a neat hole gnawed into it. I gather half a dozen of them to add to the collection. The holes are not more than a few millimetres across, with regular sloping bevels. They are the work of wood mice (Apodemus sylvaticus) seeking the nutritious kernels hiding in their woody cases. The little midden lies near a burrow in the soil that must have been roofed by part of the rotting log—this is Mouseville, Oxfordshire. The burrow continues under the adjacent log; it may well lead to a leaf-lined nest. I had seen wood mice a few times during daylight hours rustling dry leaves as they scuttled through the litter, all ears and cautious eagerness; pretty little grey-brown popeyed creatures. They really belong to the night, however, when they are out scavenging fat centipedes and bringing home beechnuts to store against hard times. The log seems to yield up more and more secrets; but it is time to move it back to its original position, and leave its underground inhabitants to their own multifarious devices.
Other mammals: I have only once seen in the wood that most voracious insectivore, and Britain’s smallest and most primitive mammal, the pygmy shrew (Sorex minutus). It appeared in the leaf litter under the King Tree in August, an animated black ball of energy that soon shot off into hiding when it realised I was there. The little shrew is famous for having to consume more than its body weight of live food each day, and won’t turn its pointy nose up at woodlice for supper, which I imagine as kind-of unpalatable crunchy biscuits. We bagged a field vole (Microtus agrestis) in one of our summer surveys. This is a very inquisitive animal, and it is easily tempted into a mammal trap. It is short-eared and snub-nosed compared with the wood mouse, and its tiny beady eyes contemplated us with apparent unconcern before its release back into the wild.
I was surpri
sed to find plenty of evidence for another creature of the underground, Mr. Mole (Talpa europaea), an animal that I am unable to think about in an objective way since first seeing E. H. Shepard’s illustrations for The Wind in the Willows. I did not expect that molehills could be thrown up from ground so densely packed with flints as that underlying Grim’s Dyke Wood, but there are several places where the rewards in worms must have repaid the effort of digging. Large molehills around the big clearing are little more than heaps of stones. I imagine Moley sitting in an armchair underground, reading the newspaper and eating marmalade sandwiches. I have never seen his enemies the weasels and the stoats, though I do not doubt that they have passed furtively through the wood in search of wood mice and voles. After all, Kenneth Grahame called these predators “the Wild Wooders,” and Lambridge Wood is an approximation to the wildest, or at least oldest, we have left in England.
In November, late in the month on one of my regular mooching visits, the wood was visited by a numinous presence. A brown hare (Lepus europaeus) loped through the trees, its implausibly long, brown-tipped ears twitching as they listened for any suspicious noise. The hare moved slowly, like a racing greyhound forced to mince around a suburban park. I had thought the hare a creature of wide fields, but here it was in the wood, questing for something—I still do not know what. No common-or-garden rabbit has ever crossed into our territory. The visit of this elegant animal, all legs and ears, made me feel curiously blessed.
More News from the Underground
In the autumn of 1683 the wood pigeons were again startled into panicky flight. A witness reported that
there was suddenly heard a strange and (for many years before not known) a most furious Commotion of the Air attended with an unusual shaking and trembling of the Earth and indeed of everything that before seemed to stand fixed upon it. Houses rocked like so many huge cradles, and in them tables, stools, trunks and chests rolled to and from with the violence of the shog; which put the people into so great a consternation, that they ran away and forsook their habitations…this Autumn Ague-fit of the Earth-Hag put us into a strange consternation all about Thame and Wallingford…a poor labouring man, a mean thrasher, being at his work in a small village two miles from Wallingford, felt this same shaking of the Earth, which he minded not at first; but when he heard the rafters of the barn begin to crack, away he ran, flung down his flail, and put the whole street in uproar.11
I cannot prove that this earthquake shook all the trees in Lambridge Wood, but if the effects were so violent at nearby Wallingford it is almost certain that it did. Even the oldest woodland ticks off no more than a moment on the scale of geological epochs, and from time to time an ancient memory stored deep in the earth is rekindled. I expect that the fault whose revived movement caused the “Ague-fit of the Earth-Hag” lay deep in the unconscious mind of southern England, in rocks contorted and shocked long before the age of dinosaurs and ammonites. The white chalk forming the backbone of the Chiltern Hills was laid down in the sea more than three hundred million years after the deeply buried rocks that hosted the fault. The “Ague-fit” reminds me that each of the building blocks that make the landscape is ultimately shaped by globally shifting tectonic plates, and that these movements will continue their inconceivably slow and inexorable march regardless of the comings and goings of mere humanity with all his woods and all his works.
Nine years before the quake caused the thrasher to throw down his flail, the geological legacy of the Chiltern chalk had inspired a new industry. George Ravenscroft set up an experimental glass factory in Henley. He was attracted to the area because of the availability of particularly fine flint—that same flint that Neolithic hunters had appreciated. I added to the collection one flint nodule that I gathered from a chalk outcrop below the wood, a stone which bears a fortuitous and appropriate resemblance to the “rother” of Rotherfield; inside, it is pure unspotted silica. Dr. Robert Plot had come across the use of flint in glassmaking in his travels around Oxfordshire, so there was a tradition of flint glass in the area.12 Henley would have been a comfortable place for George Ravenscroft to live because as a devout Catholic he could be assured of a welcome at Stonor House, where the Camoys had determinedly paid fines to maintain the practice of their faith.
The trouble with Ravenscroft’s earlier efforts to make crystal glass was a tendency for it to break into a fine covering of cracks, known as “crizzling.” The formula needed to be tweaked, but it was unclear how. Various compounds had been added to the melted flint to try to emulate the appearance of rock crystal. Eventually, replacement of lime compounds with just the right soupçon of lead oxide produced wonderful results. There is scholarly debate whether the mixture was discovered by Ravenscroft himself, or adopted from earlier experiments by Italian master craftsmen in Murano. However it originated, lead glass—“crystal”—would go on to adorn all the best tables. The early pieces made by George Ravenscroft had the emblem of a raven’s head impressed upon them,13 so they are identifiable. I had thought a piece of this glass would make a fine addition to the wood collection. A lovely, squat, two-handled posset pot seemed a particularly desirable article. I soon discovered my mistake. If pieces ever come on to the market (which they very seldom do), they fetch a fortune. Most examples are in public collections like the Victoria and Albert Museum in London, where a visitor has the paradoxical experience of looking at glass—behind glass. Lonny van Ryswyck, who made a tile from the Grim’s Dyke clay, was also able to melt our silica pebbles into a handsome green glass in one of her experiments, but it was not quite the same. I shall have to be content with my oddly shaped flint.
—
WINTER IS HERE at last. It is a clear day, and the wood somehow appears larger than usual. Television news has been full of stories of flooding. Pundits for and against man-made climate change have been exchanging words. One of the former implied that Chiltern beech trees might be threatened if the climate warms; nothing suggests warming today, but then this is weather, not climate. Icy wind whistles through the naked trees and I have to huddle inside my jacket. The frosty blue sky is riven with the trail of an aircraft—a white zip fastener across the heavens. It would not have been visible during the summer. A few branches are newly blown down, nearly every one scarred with the squirrel damage that has now become familiar. I see no sign of the culprits today—maybe they have withdrawn into the warmth of their drays. Maybe they are sharing a marmalade sandwich with Mr. Mole. The damage could have been worse. A couple of tipped-up root plates remain in the wood where whole trees were blown over, though I cannot say whether it was by the hurricane of ’87 or ’90. Beech roots do not delve deep. One might imagine that this gale could bring another one down, but though there is squeaking and complaining from trees that are rubbing together, all the trunks are holding firm. The high branches toss chaotically. Something has been through the wood: deer have left abundant droppings like small black acorns, still glistening. I scoop up a few into a plastic pot (not for the collection). What can the roe deer have found to eat? I suddenly recall the phrase “nipped in the bud”—and one of our planted hazels seems to have been topped, but nothing serious. Maybe a dog-walker sent the deer on their way, though only the hardiest, or foolhardiest, of that species would venture out in this weather. Grim’s Dyke Wood has shut down until further notice.
What I take home with me today is the dung. Like a rotting log, dung provides a special habitat—in this case one supporting specially adapted, nitrogen-loving species, all of which are part of the biodiversity of the wood. Dung provides a demonstration in miniature of ecological succession, since one species follows upon another in a set order, like dignitaries in the Lord Mayor’s Parade. It is much easier to see this at home than by repeated field visits. The droppings need to be prevented from drying out, but must not be wet. I find what works well is putting five or so fresh examples in a sealed transparent pot (the kind that olives are sold in) with some damped moss to keep the relative humidity high. Every few days
the lid is removed for an inspection with a big magnifying glass.
Within a week, little white spindles drenched in water drops rise like rocket-launchers from each pellet. They look like germinating seeds, but they are the early stages of a remarkable mould called Pilobolus. A few days later tiny black spore capsules have developed, which look like minute “hats” on top of the spindles. Many of these “hats” have water droplets just beneath them. A special mechanism prompted by the droplets “shoots” the capsules into the air—tiny black “pepper grains” of spore packages decorate the lid of the container. In nature, shot spore capsules adhere to nearby vegetation and are nibbled by passing herbivores, eventually finding their way into their dung, where they germinate and perpetuate the species. The spore release of this “hat thrower” fungus has acceleration speeds exceeding anything else in the natural world; but this is only the beginning of the parade. Small hairy white lumps now erupt from the sides of the pellet. Within a day or two these too have extended into stems, and transformed into conventional, if minute, mushrooms. Some are densely covered in white shining cells like snow (Coprinopsis stercorea); others look like miniature Japanese parasols (Coprinellus species). They are so delicate that a breath will destroy them, and their life is short, no more than a day. Their caps soon turn into a black mush—for they are tiny inkcaps, related to some species that occur commonly in the wood, like the magpie mushroom. Other droppings sprout little pink clubs of a weird mushroom relative called Stilbum. Now I wait for the cup fungi (Discomycetes) to appear: little yellow or orange discs, with a waxy look. Lasiobolus macrotricha is surrounded by long hairs, like eyelashes. There are finally some hard-to-see, black bomb-shaped fungi with hairy apertures that emerge from the droppings. Every time I incubate a sample I find something different. I intend to add “incubating deer-droppings” to the list of pastimes in my biography.
The Wood for the Trees Page 21