spruce



spruce defined in 1944 year

spruce - Spruce;
spruce - (Genus: Picea Link. Family: Abietaceas).

The name " Spruce " is derived from one of the French names for the tree, but is alien to that language and its derivation is uncertain. It probably comes from " Spruce old French for Prussia, as the genus only occurs wild in one corner of France, and was probably associated with Germany by French foresters, in the same way as British foresters associate the common' species with Norway.

The spruces are at once identified by their leaf-spray; only long shoots are found, and the needles are spirally set around them, but in most species come to lie more or less flat in one plane on horizontal branches, by reason of a twist in the short petiole at their bases. Each needle is supported on a little woody peg, and when they fall these little pegs persist, making the shoot very rough to the touch. The winter buds are small with dry, non-resinous scales, which persist on the branchlets, marking off each year's growth. The bark is thin, any thickened patches usually taking the form of roundish scales or plates, which fall away. The base of the trunk is usually more or less buttressed, and the root-system is usually shallow.

The spruces are very formal in habit, and in the open form a conical canopy, with a very erect trunk and drooping branches, which may persist almost to the ground. Every season they spring into growth, each shoot casting off its papery brown cap of bud scales, and rapidly elongating as the tender needles expand; at this stage the shoots are very susceptible to frost and mechanical injury. The loss of a leading shoot is a severe check to the tree, but it has considerable powers of recovery, even if bitten back by rabbits. Growth is soon completed and the tree then enters upon a long resting period, storing up reserves for the next spring.

The male flowers of spruce are borne in leaf-axils near the tips of the branches, and are not conspicuous. The female flowers are green globular bodies which appear in spring at the tips of new shoots, and rapidly ripen in their first season to beautiful brown pendulous cones. These cones are elongated, oval, elliptical or cylindrical, and show the spiral insertion of their thin, often papery, scales, very clearly. They open in early spring, releasing numerous minute winged seeds; after this they persist on the tree for a year pr two, before falling away, still in one piece. The seedlings have each about a dozen sickle-shaped cotyledons; they are very small and susceptible to frost, drought, and weed competition, so that in a state of nature only a small proportion survive their first year. Although they soon assume the characteristic form of the adult tree, their growth for the first few years is very slow; later it becomes rapid.

The seed of spruces is gathered in the main from fellings, sometimes from standing trees, care being taken to pick only the recently ripened cones from the tips of the branches. The seed is very fine, ranging from 60,000 to 200,000 grains per lb., and retains its germinative power for 2 or 3 years. Sowings require a light covering of coarse sand, with overhead screens to shield the delicate seedlings from late night frosts and strong sunlight; the young trees grow naturally in semi-shade even in a wild state. Seedlings are not big enough to transplant until they are two years old, and seldom large enough for forest use until they have spent a further 2 years in the transplant lines. To raise really sturdy plants, 18 inches and over in height, a second transplanting is usually necessary, so that it is not unusual to plant out spruces as old as 6 years.

The spruces are trees of strongly marked sylvicultural characteristics. They endure deep shade but, except in the seedling stage, thrive very well in full light; their canopy casts a dense shade in which no green plants can grow. They are somewhat frost-tender in youth, as late spring frosts which occur in hollows frequently catch their developing foliage at a tender stage. Once above the frost level-they cease to suffer setbacks, and growth is rapid; but in valleys they should have a nurse species such as Scots Pine or natural willow or birch, for the first few years after planting. The young foliage is susceptible to damage by salt winds, and spruces cannot be grown near the seaside unless shelter is given. They do not thrive in smoky areas, as their needles must last them for several years.

The outstanding feature of the spruces, however, is their normally shallow rooting system, which affects their growth and culture in many ways. As a rule, their roothold is poor, and if suddenly exposed to the force of the wind, grown trees go over like ninepins; trees always exposed to the winds are firmer on/dry sites, however, as their roots strike deeper in search of moisture. Spruces have a high water requirement, but as their root system is adaptable, it is usually met throughout Britain, even on the drier hilltops. They fail on acid soils, however, probably through physiological drought, being unable to absorb moisture against the stronger pull of soil acids. Their success on damp soils is due to their surface roots obtaining sufficient air, whilst those of other trees have to penetrate deeper and are literally drowned. Spruces cannot stand acid soils, which in some parts of Britain are indicated by a ground- covering of heather; on such sites their needles remain stunted and turn yellow, and the young trees after standing still for some years, finally wither and die. On chalk soils spruces meet with a measure of success wherever the overlying loam is fairly thick; where chalk comes near the surface they die off after 30 or 40 years' growth. Apart from these extremes, they thrive on any soil, make only moderate demands on fertility, and enrich the store of humus by their heavy leaf fall.

When planting spruces it is essential to ensure that their roots obtain ample aeration. A usual method is to cut a turf, invert it, and set it either above ground (on wet sites where the turning is combined with the drainage system) or in its former position (on dry sites), A notch is then cut through the turf and the plant inserted in this, so that its roots may be spread out between the turf and the ground surface; as moisture rising from the ground collects between the two surfaces, trees so planted seldom suffer from drought. Alternatively, spruces may be planted in the slice turned up by a plough, or shallow-planted in turfy ground by notching and raising the grassy layer so that their roots may be spread out beneath it. After planting, one or two seasons of " check " normally ensue; the young trees make little headway until their roots are well established. If they are deep-planted, " check " may last for several years. Once " out of check " growth is rapid; each year a long leader is put on, and increases in volume over the whole plantation are quickly made, whilst the crowns expand so speedily that thinnings must be made every two or three years to prevent the stems being too far drawn up.

Spruces may be planted pure, or mixed with, or nursed by, a light-demanding species such as Scots Pine. They suffer no harm if temporarily outgrown by their partner, and endure such dense shade that they may be used for underplanting or for filling in gaps in sparsely stocked plantations of other conifers. When grown pure, a usual planting distance is 5 feet each way.

Spruce poles are often of particular value on account of their dead straightness, especially for the masts of small boats, flagpoles, etc. Thinnings also produce a big volume of pitwood, but are of no value for fencing unless treated with preservative, being otherwise perishable. Larger poles we used for ladders and for scaffolding, so that there should be a good outlet for thinnings of all sizes; poles of these descriptions have been imported in quantity from northern Europe for many years past.

The timber of the spruces is known as White Deal, or Whiter wood, and is one of the principal timbers imported to Britain from the Baltic and North America. It is creamy white or pale brown in colour, with no distinct heart, strong, readily worked by tools, attractive in appearance, but not durable. It is very widely used for the indoor work of houses, such as flooring, skirting, etc., kitchen furniture, and box-making, being the usual material for constructing cheap packing cases. For this purpose, it is rendered especially suitable by its power of holding nails even when thinly sawn, its clean appearance and its Comparative freedom from resin. Spruce is also used in quantity as firewood» As rotary-cut veneer, it is one of the principal ingredients of plywood, and is also used for match-boxes, and chip baskets for fruit; when sawn and split into the smallest of sizes, it can also be used for match-stalks. Sprucewood is one of the most suitable timbers for paper-making owing to its comparative lack of resins which are difficult to eliminate from other coniferous timbers. In the form of pulp and paper, enormous quantities are normally imported annually from Canada and Scandinavia. Being light in proportion to its strength, spruce- wood is also used in aircraft construction.

Slow-grown sprucewood, with many annual rings to the inch, and free from knots, has good technical qualities for fine joinery, mouldings, carvings, rails, and handles. An interesting use for material of this class is in the sounding-boards of violins. Such slow-grown wood is formed mainly by semi-suppressed trees in natural forests, being the result of insufficient light reaching the growing tree. Dead knots are a serious fault in much spruce timber, being dark in colour, hard and apt to fall away when it is cut into thin sections; even very small dead knots render it useless for plywood purposes, but in large trees they seldom extend far from the centre of the bole; brashing and high pruning are therefore important operations in growing high-class timber Foreign exporters, handling huge quantities of White Deal from vast natural forests, are able to grade it closely by reference to freedom from knots, closeness of grain, etc., so that the importer is offered a range of grades at various prices and may purchase according to the technical requirements of his work in hand.

From the above account it will be seen that the spruces are amongst the most important timber producers of the northern hemisphere, and their rapid growth in Britain fits them for commercial planting on a large scale. They enjoy the moist climate of western Britain, and are useful for planting reclaimed marshy areas where other conifers cannot thrive, provided the marsh soils are not too acid for them. Rotations are usually short, around 70 to 100 years; after which time butt-rot sets in many situations. The comparative scarcity of large spruces is therefore largely due to their early maturity, which calls for prompt felling as soon as commercial timber size is reached.

The spruces are all trees of cool temperate regions, extending to the tree line towards the North Pole, and occurring only in the mountains in lower latitudes. About thirty species are known, of which three occur in Europe, and others in northern Asia, China, Japan, the Himalayas, and across North America.

The Norway Spruce (Picea excelsa, Link) (syn. P. Abies, L.). G. Fichte, Rottanne; F. Pesse, épicéa, Spruce; W. Pefrwydden. Italian, Abete rozzo. Christmas Tree or Common Spruce.

As a wild tree the Norway Spruce has a limited distribution in Europe only. It is found as a mountain tree throughout the Alps and Carpathians, extending from south-eastern France to Rumania. Farther north it descends to the plains of Poland, Russia, and Scandinavia. To the north-east it is succeeded by the Siberian Spruce (P. obovata, Ledebour) which extends across northern Asia, but does not thrive in Britain. To the south-east it is replaced by P. omorika and P. oriental. Except in Norway, spruces do not occur naturally on the western coasts of Europe.

The Norway Spruce may be identified by the dark green colour of its blunt thick needles, the red-brown shade of the shoots, and its long cones with thick, straight-edged scales. Young plants are familiar to everyone as Christmas Trees. These trees are raised from seed by nurserymen and planted out on agricultural land at about 2 feet apart each way. They are thinned out for market according to the demand for the various sizes; the large trees must be given ample room if they are to keep their branches low down fully " furnished " with green leaves, as this trade demands. The financial yield per acre is frequently very high, considering the short term of years needed for the crop to become profitable. The cult of the Christmas Tree is of recent introduction from northern Europe, though the custom of decorating rooms with evergreens at Yule-tide dates back to pre-historic times.

By-products of this tree are a fine resin known as Burgundy Pitch, obtained by tapping the living stem, and used in varnishes; and Spruce Beer, a spiced drink brewed from sugar and water, to which the leaves of spruce contribute flavouring and medicinal properties. The bark may be used for tanning.

In Germany and the Baltic countries the Norway Spruce is the most important economic timber producer. Intensive study has been devoted to its culture, chiefly by means of natural regeneration, and numerous local forms adapted to various localities have been identified. A wide variety of nurserymen's forms are also known. The date at which the Norway Spruce was introduced to Britain is unknown, but was probably earlier than 1500. Although widely cultivated here, it has not tended to become naturalised, and naturally-sown seedlings are rare. It reaches heights up to 150 feet in Britain, and over 200 feet in Europe. Well-grown trees are very ornamental, but somewhat short-lived; rot at the butt is often followed by wind-break, so that felling is advisable when maturity is reached, often under 100 years of age. Girths up to 14 feet.

The importance of Norway Spruce in British forestry lies in its adaptability to shade, poor soils and damp situations, combined with rapid growth and the quality of its timber, which compares fairly well With imported White Deal. It is less frost-tender than the Sitka Spruce, but probably not so well adapted to our climate as that species. Seed is ripened in Britain in most seasons, some 70,000 grains going to the lb. Figs. 4, 5, 6.

The Sitka Spruce (Picea sitchensis, Carrière)- G. Sitkafichte. Menzies, Tideland, or Silver Spruce. This is an important tree of the Pacific coast of British Columbia and southern Alaska (from which region it takes its name), which is acquiring prominence in British plantations by virtue of its rapid and vigorous growth on poor and damp soils, more particularly in the high rainfall regions along the western coast.

Sitka Spruce is readily distinguished from Norway Spruce by the blue or slate grey tinge of its stiff, flat needles, which are sharply pointed and silvery underneath. Young trees are unattractive in appearance, being regular in outline and ill-proportioned between trunk and branches; they are useless as Christmas trees. As they grow, the dead needles of the leading shoots persist on the smooth bark of the straight erect trunks. The full-grown tree, of which but few specimens are as yet existing in Britain, is magnificent in Size and form, the massive smooth-barked, buttressed trunk rising with gentle taper to a height of over 130 feet, with widespread, gracefully drooping side branches. Occasionally, thin flat surface scales form on the bark, but these soon fall away. The cones are distinctive arid rather pretty, small, pale brown, oval, with papery scales which have a crinkled margin. The seed is very fine (200,000 to the lb.). Figs. 1d, 3a.

The timber of Sitka Spruce is highly valued for the finest joinery, and owing to its great strength compared to its light weight, is of special value in aircraft construction. Large butts yield a high- grade veneer when rotary-cut, which is used to form plywood for aeroplanes. This tree is also an important pulpwood producer. Large quantities of selected high-grade timber are normally imported from Canada, but when the British plantations reach timber size it is probable that selected butts will equal the imported material in quality. Thinnings are already important for pitwood. As the tree has only been grown here for a little over 100 years, its ultimate size is unknown, but it looks likely to reach the same dimensions as in its homeland, where it exceeds 200 feet in height. Young plantations rapidly produce a high volume of timber per acre, and require frequent thinnings. Heights of 130 feet, girths 14 feet, occur in Britain already.

The Servian Spruce (Picea omorika, Pancic), Serbian, Smrc., is a rare and interesting spruce from the Balkans, distinguished by its flat, dark green needles, which give its foliage an appearance not unlike the Silver Fir. Its growth is rapid, the trunk being very slender and the crown narrow. It thrives well in Britain and is a valuable ornamental tree. In its homeland it produces useful timber, and as it grows naturally upon limestone hills, it may prove of value in Britain for the afforestation of similar sites.

The Weeping Spruce (Picea morinda, Link), West Himalayan Spruce, Morinda, or Khutrow, is one of the most beautiful and striking of ornamental conifers. It is readily identified by its long, curved, needles, which are placed evenly around the drooping branchlets. Its pendulous habit of growth, with drooping branches and vertically hanging foliage sprays, are perhaps connected with the heavy snowfall in- its high Himalayan homeland, where it is an important timber tree at altitudes around 10,000 feet. In Britain it attains a fair size, but is only grown for decoration; its sheer cascades of graceful dark green foliage make it by far the handsomest of all pendulous conifers. Fig. 2e.

Other foreign Spruces. The timber of the eastern American Spruces is imported to Britain in large quantities, both in the solid form and as paper pulp, but the living trees have not been successful here, even as ornamental trees. The principal species are the White Spruce (P. alba, Link.), the Black Spruce (P. nigra, Link.), and the Ried Spruce (P. rubra, Link.). Farther west, other species occur which may repeat the success of the Sitka Spruce in the British woodlands, but they are little planted as yet, as Our knowledge of their behaviour under forest conditions is still incomplete. The Rocky Mountain Spruce (P. engelmanni, Engelmann) is an important timber tree in British Columbia. The Blue Spruce (P. pungens, Engelmann) is grown for decoration in gardens, as is also a weeping spruce from California called P. breweriana, Watson. (Brewer's Spruce).

Asiatic spruces are numerous, extending from Japan across Siberia and the Himalayas to the Caucasus. None is of-note in British forestry,[though many are grown in gardens, including the very prickly Tiger-Tail Spruce (P. polita, Carrière) or Tora Momi, from Japan. A beautiful and distinct form is the Oriental Spruce (P. orientalis, Carrière), G. Sapindusfichte, found in Asia Minor. Its needles are very short, blunt, broad, and dark green in colour, giving a rich velvety effect in the mass. Its timber is similar to that of Norway Spruce, and as a decorative tree it thrives equally well in Britain, so that it may be useful for commercial planting here.

The forestal value of imported spruces is not easily assessed from ornamental specimens in garden collections, where the climate may be locally unsuitable, or polluted by coal smoke. Frequently, the imported seed has been gathered from bushy forms (from which it is most easily collected), and not from tall forest trees. All spruces grow slowly in youth, and on some soils they will not grow at all; hence their vigour cannot be judged until they have been tested on various soils and sites known to be suited to the other introduced species which have proved their worth in our climate. Moreover, they are essentially " successor " trees, requiring some form of shelter or nursing in. their early stages. Such trees cannot be fairly tested in pure plantations, but when correct sylvicultural methods are applied to them, may prove to be valuable and attractive additions to our forest flora. Heather areas on which spruce is frequently a total failure as a pure crop, may thus be afforested with these trees by using pine nurses, or by underplanting older tree crops with them.

pictures for spruce

cones of important introduced conifers cones of important introduced conifers. >>>>

leading shoots leading shoots. >>>>

leaf sprays leaf sprays. >>>>

norway spruce norway spruce. >>>>

norway spruce norway spruce. >>>>

norway spruce norway spruce. >>>>


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