oak defined in 1944 yearoak - Oak;
oak - Quercus pedunculata Ehrh, and Quercus sessiliflora Salis., formerly regarded as one species (Quercus robur L.), are similar in forest characteristics and are described together, points of difference being appended later; (Fagacea). G. Eiche; F. Chêne; W. Derw, Derwen; E. Dâir; A.-S. Ac.; Scots, Aik.
A tree of wide variation in size and form, the oak may readily be identified in winter by the pointed many-scaled buds clustered at the tips of the twigs, which are themselves often ribbed or ridged, and show frequent changes in direction. This tendency to crooked growth is a characteristic of the oak, causing the wide-spreading crown of open-grown trees; only in the close woodland, in keen competition with others of its kind, may it be induced to develop a tall straight bole. The bark of young branches is smooth and dark grey, on older trunks it is light grey, thick and rugged.
The leaves are always slow to appear, usually opening in early May. They are alternate, simple, and oval in general shape, with a sinuous outline that gives the appearance of many lobes. Mid- green in colour, they change to a uniform dull brown in late October, but are slow to fall.
The flowers follow the leaves, the sexes being in separate catkins on the same tree. The male flowers are grouped in knot-like clusters on long pendulous stalks; each consists of 6 small green sepals and about the same number of anthers. The female flowers, borne in groups of four or five on a short axis, are inconspicuous, the 3 carpels being concealed within a green cupule, with a trifid red stigma projecting. Pollination is by wind, and only one ovule in each flower develops, being surrounded by the enlarging cupule with its roughish exterior, which becomes the familiar acorn-cup.
The oak-seed, or acorn, is oval in shape, about half an' inch long, green at first, but ripening to brown in October, when it fells from the cup, showing a conspicuous pale semi-circular scar at the point of attachment. The oak is irregular in its production of seed, " Mast " years occurring at varying intervals. In most seasons a few trees produce a few seeds, but sometimes scarcely a single tree can be found in bearing over a wide area. The seed is distributed more or less accidentally by animal agencies. It is a favourite food of pigs, who bury some acorns whilst grubbing for others, and of squirrels, who may or may not return to their hidden stores. Pheasants and wood-pigeons are also fond of acorns.
Native to Britain and widespread in Europe, âie oaks are represented by allied species in North America, North Africa, Asia Minor, and the Orient.
The Cork Oak (Quercus suber L.), an evergreen species found in Iberia and Morocco, produces cork, obtained from the bark of the living tree.
Seed is collected from beneath the trees in October and may be sown at once or stored until spring, spread out in a cool, moist place. One lb. contains around 100 acorns. Sowing presents little difficulty, but the beds must be protected against marauding birds and rodents. The cotyledons remain below ground on germination, and the first leaves are often unlobed. Seedling growth is rapid, and a stout tap root is soon developed. Oaks are fit for planting out as first or second year seedlings. If they cannot be moved then
hey must be transplanted before the top root gets too big, for a further year or more in nursery lines.
Direct sowing in the forest is practicable, but losses from animals, e.g. voles, are apt to be very heavy.
In establishing oak woods it is usual to provide the main species with a nurse - usually a quick-growing conifer; but advantage may also be taken of natural cover, such as hazel coppice or birch. Alternatively, the oaks may be set so closely - 3 feet or less apart - that they soon nurse one another. Where nurses are absent, growth is slow or negligible, probably because each season's shoots are cut back by late frosts.
The oak is a light-demanding tree, and must have its head free when once it rises above the level of late frosts. Its natural enemies, mainly insects and fungi, are literally too numerous to mention, but it survives them all - even complete defoliation in spring does not kill it - as it normally has a second flush of leaf when the long " Lammas " shoots are produced. It is resistant to every form of harmful influence - city smoke, salt winds, intense winter cold, floods, storms, and poor soil. But although oak will survive under such conditions, it will only thrive and produce good timber on the best of well-drained loams - agricultural soils, in short; and its planting on any scale should be governed accordingly.
Oak will coppice, but only if felled before maturity, and coppice oak was formerly valued as fuel and for bark. It is not suited for other purposes, and coppice areas are now of negligible value. Oak is a useful firewood and a standard timber for charcoal production. Its bark was formerly in great demand as a tanning material, being stripped from the log (sometimes from the standing tree) with special barking irons.
The sapwood of oak is lighter in colour than the heart and is perishable when exposed to moisture. Being fairly thick, it constitutes a large proportion of the volume of young trees; hence the value and utility of oak in the log increases rapidly with increasing girth since the larger trees contain a smaller percentage of sapwood.
The heartwood of oak is light or mid-brown in colour, with a pronounced even grain and distinct medullary rays. Not only is it strong and tough, but it is attractive in appearance and durable under all conditions. This is due in large measure to the presence of tannic acids, which react with the iron of tool-blades to produce the ink stains frequently seen on newly felled oak.
The utilisation of oak to its best advantage involves a number of distinct crafts, tools and methods.
In the round, oak is not of great utility, as the outer sapwood is not durable, but it often is used for hedging stakes and pickets, and occasionally as pitwood.
Cleft oak is split on the radius of the log, i.e. in the plane of the medullary rays. Clean-grown trees about one foot in diameter are the most suitable, and the work is done in the woodlands as soon as they are felled; it is a useful method of utilising thinnings. The log is cross-cut to the length required with the saw, and first split in half with axe and wedges; from each half-cylinder, two or more segments are then split off; each runs right to the centre and includes its due share of heartwood. These segments are then trimmed up and pointed, for use as fence-stakes, or squared off with the saw as fencing pales, both being very durable.
A refinement of the cleaver's craft is the preparation of barrel staves, especially for brandy. For this purpose, large, clean-grown butts are needed, and the sapwood and inner heart are both discarded. The outer heartwood is sawn across to the desired length, and split radially into as many segments as possible - each segment containing at least one unbroken medullary ray, since it is the cells of these that prevent the escape of water and alcohol. The segments are shaped and shaved to exact dimensions, and when used in the barrel they lie at right angles to their original position in the tree - i.e. with their long axis tangential instead of radial.
Cleaving may also be employed to reveal the " silver grain " of oak, by cutting along the rays to expose the figure, much fine old panelling having been prepared in this way.
Hewn oak is prepared in the wood from logs or limbs of any fair size with the hewing axe, which is bevelled on one face and flat on the other. The sapwood is thereby more or less completely removed, and the original cylinder of the trunk is reduced to a square or octagon. This method has two advantages over sawing - it does not tear through the exposed wood vessels, and hence hewn oak is more resistant to decay, and it enables any bend or fork in the timber to be followed where required without loss or waste. It was therefore the standard practice in the preparation of beams, etc., for building, most of which, where exposed, still show the mark of the axe; and also in the preparation of structural timbers in ship-building.
Sawn oak is used for a multitude of purposes in a wide range of dimensions, from great beams and struts right down to picture framing. Large quantities are used in the construction of lorries and railway rolling stock, especially goods waggons. It is also in demand for mines, ship-building, and heavy constructional work. Indoors it is valued for mouldings, panelling and flooring, and for a wide range of furniture, either in its natural light brown hue or stained and treated to give a wide range of decorative effects.
Oak is sometimes sawn radially to expose the silver grain, but this process involves much waste with all but the largest of logs.
As Veneer y oak is usually sliced across a radial face, instead of being peeled tangentially. Here again the object is to expose as much as possible of the silver grain.
When softened by steam, oak may be bent, a process chiefly of value in chair-making. It is also useful for turnery, selected squares of seasoned heartwood being spun id a lathe against the craftsman's chisel. Finally, it may be carved - when fully seasoned it retains its shape well, and is used for artistic as well as merely decorative work.
Oak will usually yield marketable timber at 120 years of age, but is often left to stand another century. Its maximum age is unknown, but a thousand years is quite a possibility. All such age determinations depend on ring counts, i.e. on the assumption that every year the tree must lay down a fresh outer ring of wood. But many old oaks cease to expand in girth, and any rings laid down must be quite imperceptible. Oak frequently attains a height of 100 feet, and large girths are usual, 28 feet having been recorded.
Underplanting is an important factor in the cultivation of plantation oak. After 80 years or so, the crowns open out and let in so much light that the soil below deteriorates and requires protection by a shade-bearing species, beech or hornbeam being usually employed.
It is difficult to over-estimate the past importance of oak to England. Grown everywhere, it touched life at every point from the cradle to the coffin. It was the usual " standard " tree of the coppice-with-standards system of forestry in the south, whilst in ironstone districts vast natural forests were felled to provide charcoal for smelting. It was essential for the building of wooden warships, especially so in the years from the Armada to Trafalgar. To provide the forks and bends whose outline gave inherent strength to the wooden hulls, oak was especially planted at wide distances in the old Crown Woods.
On paper, it is easy to prove that it can never pay to plant oak at the present time. On the best of soils it makes a slow return, the early thinnings being of little or no value. Allowing for compound interest on the capital invested, there is no apparent profit in the venture. But taking a wider view, "there must come a time when existing stocks of standing oak, at home and abroad, are depleted. The demand for a timber of such varied utilisation is unlikely to diminish, and prices Will rise accordingly. Further, an oakwood is a durable investment. Being almost indestructible, if it is not desired to fell it as soon as mature, it may be left to stand another 50 years or so as a reserve store of timber and capital.
The Sessile, or Durmast, oak is best distinguished from the Pedunculate by its long-stalked leaves and unstalked flowers. Its acorns taper to a point, those of the pedunculate oak being blunt, or swollen at the apex; thus they are readily distinguished at sowing time. Other points of difference are less well marked, and intermediate forms occur. The true Sessile Oak, which is dominant on the Silurian soils of Wales, is of more erect growth than the pedunculate. The timber of both is equally valuable. Fig. 3, a-e.
The Turkey oak (Quercus cerris L.), introduced from the Balkans, has leaves with deep-cleft, acute-angled lobes, buds with long stipules, and hairy acorn-cups. Its growth, even on poor soils, is rapid, but its timber is not durable, and it splinters so much when burned that it is useless as firewood. It might possibly be used for indoor purposes. Fig. 3, f, g, h.
The holm or evergreen oak (Quercus ilex L.) is only grown in Britain as an ornamental tree, having been introduced from the Mediterranean, to which climate its foliage is more suited. The dark green, leathery leaves are oval in outline, sometimes spined, and cast a very deep shade; they last for 2 years. The acorns persist on the tree for eighteen months, falling in their second winter. The bark is thin, jet black and scaly, and the brownish wood is very dense, hard and heavy. It is used for cabinet-making, makes a good firewood and an excellent charcoal. Fig. 3, i,j.
Of American oaks, the valuable White Oak (Quercus alba L.) can be grown in Britain, as can the various species of Red Oak (Q. rubra L., Q. coccinea Wangenh., and Q. palustris Münch.). Not only do these produce useful timber, but their vivid scarlet and crimson autumn tints make them favourite subjects for ornamental planting.
Fig. 14 illustrates the long, clean, straight stems obtained by growing oaks closely in plantations. The other oaks illustrated are " open-grown," and their low crowns lessen the length of useful timber.
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