The Wood for the Trees: The Long View of Nature from a Small Wood. Richard Fortey
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 caterpillars develop a shade of pinky brown, and since they can be seventy millimetres long fully grown they are quite enough to give a shock to any casual stroller who comes across one; especially when their 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.
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.