Wood and Forest

List of 66 Common Woods Arranged in the Order of Their Weight.

List of 66 Common Woods Arranged in the Order of Their Strength.

List of 66 Common Woods Arranged in the Order of Their Elasticity.

List of 66 Common Woods Arranged in the Order of Their Hardness.

THE PRINCIPAL SPECIES OF WOODS.

• References:*
  • Sargent, Jesup Collection.
  • Sargent, Manual.
  • Britton.
  • Roth, Timber.
  • Hough, Handbook.
  • Keeler.
  • Apgar.
  • Mohr. For. Bull., No. 22.
  • Fernow, Forestry Investigations.
  • Lumber Trade Journals.
  • Baterden.
  • Sargent, Silva.
  • Sargent, Forest Trees, 10th Census, Vol. IX.
  • Boulger.
  • Hough, American Woods.
  • Snow.
  • Lounsberry.
  • Spaulding. For. Bull., No. 13.
  • Sudworth. For. Bull., No. 17.
  • Forest Service Records of Wholesale Prices of Lumber, List. A.
    
    
  • For particular trees consult For. Serv., Bulletins and Circulars. See For. Service Classified List of Publications.

* For general bibliography, see p. 4.

Chapter IV.

THE DISTRIBUTION AND COMPOSITION OF THE NORTH AMERICAN FORESTS.

The forests of the United States, Map, Fig. 44, may be conveniently divided into two great regions, the Eastern or Atlantic Forest, and the Western or Pacific Forest. These are separated by the great treeless plains which are west of the Mississippi River, and east of the Rocky Mountains, and which extend from North Dakota to western Texas.¹

The Eastern Forest once consisted of an almost unbroken mass, lying in three quite distinct regions, (1) the northern belt of conifers, (2) the southern belt of conifers, and (3) the great deciduous (hardwood) forest lying between these two.

(1) The northern belt of conifers or "North Woods" extended thru northern New England and New York and ran south along the Appalachians. It reappeared again in northern Michigan, Wisconsin and Minnesota. White pine, Fig. 45, was the characteristic tree in the eastern part of this belt, tho spruce was common, Fig. 56, p. 213, and white and Norway pine and hemlock distinguished it in the western part. Altho the more valuable timber, especially the pine, has been cut out, it still remains a largely unbroken forest mainly of spruce, second growth pine, hemlock and some hardwood.

(2) The southern pine forest formerly extended from the Potomac River in a belt from one to two hundred miles wide along the Atlantic coast, across the Florida peninsula, and along the gulf of Mexico, skipping the Mississippi River and reappearing in a great forest in Louisiana and Eastern Texas. It was composed of almost pure stands of pine, the long-leaf, Fig. 46, the short-leaf, and the loblolly, with cypress in the swamps and bottom lands. In southern Florida the forest is tropical, Fig. 47, like that of the West Indies, and in southern Texas it partakes of the character of the Mexican forest.

(3) Between these north and south coniferous belts, lay the great broad-leaf or hardwood forest, Fig. 48, which constituted the greater part of the Eastern Forest and characterized it. It was divided into two parts by an irregular northeast and southwest line, running from southern New England to Missouri. The southeast portion consisted of hardwoods intermixed with conifers. The higher ridges of the Appalachian Range, really a leg of the northern forest, were occupied by conifers, mainly spruce, white pine, and hemlock. The northwest portion of the region, particularly Ohio, Indiana, and Illinois, was without the conifers. It was essentially a mixed forest, largely oak, with a variable mixture of maples, beech, chestnut, yellow poplar, hickory, sycamore, elm, and ash, with birch appearing toward the north and pine toward the south.

Taking the Eastern Forest as a whole, its most distinguishing feature was the prevalence of broad-leaved trees, so that it might properly be called a deciduous forest. The greatest diversity of trees was to be found in Kentucky, Tennessee and North Carolina, and this region is still the source of the best hardwood lumber.

This great eastern forest, which once extended uninterruptedly from the Atlantic to the Mississippi and beyond, has now been largely lumbered off, particularly thru the middle or hardwood portion, making way for farms and towns. The north and south coniferous belts are still mainly unbroken, and are sparsely settled, but the big timber is cut out, giving place to poorer trees. This is particularly true of the white pine, "the king of American trees," only a little of which, in valuable sizes, is left in Michigan, Wisconsin and Minnesota. In the same way in the south, the long-leaf pine, once the characteristic tree, is fast being lumbered out.

The Western or Pacific forest extends two great legs, one down the Rocky Mountain Range, and the other along the Pacific coast. Between them lies the great treeless alkali plain centering around Nevada, Fig. 49. In these two regions coniferous trees have almost a monopoly. Broad-leaved trees are to be found there, along the river beds and in ravines, but they are of comparatively little importance. The forest is essentially an evergreen forest. Another marked feature of this western forest, except in the Puget Sound region, is that the trees, in many cases, stand far apart, their crowns not even touching, so that the sun beats down and dries up the forest floor, Fig. 50. There is no dense "forest cover" or canopy as in the Eastern Forest. Moreover these western forests are largely broken up, covering but a part of the mountains, many of which are snow-clad, and interrupted by bare plains. Along the creeks there grow a variety of hardwoods. It was never a continuous forest as was the Eastern Forest. The openness of this forest on the Rockies and on the eastern slopes of the Sierra Nevadas is in marked contrast to the western slopes of the Sierras, where there are to be seen the densest and most remarkable woods of the world, Fig. 51. This is due to the peculiar distribution of the rainfall of the region. The precipitation of the moisture upon the northwest coast where the trees are dripping with fog a large part of the time, is unequaled by that of any other locality on the continent. But the interior of this region, which is shut off by the high Sierra Nevadas from the western winds, has a very light and irregular rainfall. Where the rainfall is heavy, the forests are dense; and where the rainfall is light, the trees are sparse.

Along the Rockies the characteristic trees are Engelmann's spruce, bull pine, Douglas fir, and lodgepole pine. As one goes west, the variety of trees increases and becomes, so far as conifers are concerned, far greater than in the east. Of 109 conifers in the United States, 80 belong to the western forests and 28 to the eastern. The Pacific forest is rich in the possession of half a dozen leading species—Douglas fir, western hemlock, sugar pine, bull pine, cedar and redwood.

But the far western conifers are remarkable, not only for their variety, but still more for the density of their growth, already mentioned, and for their great size, Fig. 52. The pines, spruces and hemlocks of the Puget Sound region make eastern trees look small, and both the red fir and the redwood often grow to be over 250 feet high, and yield 100,000 feet, B.M., to the acre as against 10,000 feet, B.M., of good spruce in Maine. The redwood, Fig. 53, occupies a belt some twenty miles wide along the coast from southern Oregon to a point not far north of San Francisco and grows even taller than the famous big trees. The big trees are the largest known trees in diameter, occasionally reaching in that measurement 35 feet.

The big tree, Fig. 54, occurs exclusively in groves, which, however, are not pure, but are scattered among a much larger number of trees of other kinds.

The great and unsurpassed Puget Sound forest is destined to be before long the center of the lumber trade of this country.

These two great forests of the east and the west both run northward into British America, and are there united in a broad belt of subarctic forest which extends across the continent. At the far north it is characterized by the white spruce and aspen. The forest is open, stunted, and of no economic value.

Taking all the genera and species together, there is a far greater variety in the eastern than in the western forests. A considerable number of genera, perhaps a third of the total, grow within both regions, but the species having continental range are few. They are the following: Larch (Larix laricina), white spruce (Picea canadensis), dwarf juniper (Juniperus communis), black willow (Salix nigra), almond leaf willow (Salix amygdaloides), long leaf willow (Salix fluviatilis), aspen (Populus tremuloides), balm of Gilead (Populus balsamifera), and hackberry (Celtis occidentalis).

Footnote 1:

ORIGINAL FOREST REGIONS OF THE UNITED STATES.

THE DISTRIBUTION AND COMPOSITION OF NORTH AMERICAN FORESTS.

• References:*
  • Sargent, Forest Trees, Intro., pp. 3-10.
  • Bruncken, pp. 5-16.
  • Roth, First Book, pp. 209-212.
  • Shaler, I, pp. 489-498.
  • Fernow, For. Inves., pp. 45-51.
  • Fernow, Economics, pp. 331-368.

* For general bibliography, see p. 4.

Chapter V.

THE FOREST ORGANISM.

The forest is much more than an assemblage of different trees, it is an organism; that is, the trees that compose it have a vital relation to each other. It may almost be said to have a life of its own, since it has a soil and a climate, largely of its own making.

Without these conditions, and without the help and hindrance which forest trees give to each other, these trees would not have their present characteristics, either in shape, habits of growth or nature of wood grain. Indeed, some of them could not live at all.

Since by far the greater number of timber trees grow in the forest, in order to understand the facts about trees and woods, it is necessary to know something about the conditions of forest life.

A tree is made up of three distinct parts: (1) the roots which anchor it in the ground, and draw its nourishment from the moist soil; (2) the trunk, or bole, or stem, which carries the weight of the branches and leaves, and conveys the nourishment to and from the leaves; (3) the crown, composed of the leaves, the branches on which they hang, and the buds at the ends of the branches. As trees stand together in the forest, their united crowns make a sort of canopy or cover, Fig. 55, which, more than anything, determines the factors affecting forest life, viz., the soil, the temperature, the moisture, and most important of all, the light.

On the other hand, every species of tree has its own requirements in respect to these very factors of temperature,—moisture, soil and light. These are called its silvical characteristics.

SOIL.

Some trees, as black walnut, flourish on good soil, supplanting others because they are better able to make use of the richness of the soil; while some trees occupy poor soil because they alone are able to live there at all. Spruce, Fig. 56, will grow in the north woods on such poor soil that it has no competitors, and birches, too, will grow anywhere in the north woods. In general, it is true that mixed forests, Fig. 57, i.e., those having a variety of species, grow on good loamy soil. The great central, deciduous Atlantic Forest grew on such soil until it was removed to make room for farms. On the other hand, pure stands—i.e., forests made up of single varieties—of pine occupy poor sandy soil. Within a distance of a few yards in the midst of a pure stand of pine in the south, a change in the soil will produce a dense mixed growth of broad-leaves and conifers.

The soil in the forest is largely determined by the forest itself. In addition to the earth, it is composed of the fallen and decayed leaves and twigs and tree trunks, altogether called the forest floor. It is spongy and hence has the ability to retain moisture, a fact of great importance to the forest.

MOISTURE.

Some trees, as black ash and cypress, Fig. 58, and cotton gum, Fig. 59, grow naturally only in moist places; some, as the piñon and mesquite, a kind of locust, grow only in dry places; while others, as the juniper and Douglas fir, adapt themselves to either. Both excessively wet and dry soils tend to diminish the number of kinds of trees. In many instances the demand for water controls the distribution altogether. In the Puget Sound region, where there is a heavy rain-fall, the densest forests in the world are found, whereas on the eastern slopes of the same mountains, altho the soil is not essentially different, there are very few trees, because of the constant drouth.

TEMPERATURE.

The fact that some trees, as paper birch and white spruce, grow only in cold regions, and some, as rubber trees and cypress, only in the tropics, is commonplace; but a fact not so well known is that it is not the average temperature, but the extremes which largely determine the habitat of trees of different kinds. Trees which would not live at all where there is frost, might flourish well in a region where the average temperature was considerably lower. On the other hand, provided the growing season is long enough for the species, there is no place on earth too cold for trees to live. Fig. 60.

In general, cold affects the forest just as poor soil and drought do, simplifying its composition and stunting its growth. In Canada there are only a few kinds of trees, of which the hardwoods are stunted; south of the Great Lakes, there is a great variety of large trees; farther south in the southern Appalachian region, there is a still greater variety, and the trees are just as large; and still farther south in tropical Florida, there is the greatest variety of all. The slopes of a high mountain furnish an illustration of the effect of temperature. In ascending it, one may pass from a tropical forest at the base, thru a belt of evergreen, broad-leaved trees, then thru a belt of deciduous broad-leaved trees, then thru a belt of conifers and up to the timber line where tree life ceases. Figs. 61, and 62.

LIGHT.

More than by any other factor, the growth of trees in a forest is determined by the effect of light. All trees need light sooner or later, but some trees have much more ability than others to grow in the shade when young. Such trees, of which maple and spruce are examples, are called tolerant, while others, for instance, larch, which will endure only a comparatively thin cover or none at all, are called intolerant. The leaves of tolerant trees endure shade well, so that their inner and lower leaves flourish under the shadow of their upper and outer leaves, with the result that the whole tree, as beech and maple, makes a dense shadow; whereas the leaves of intolerant trees are either sparse, as in the larch, or are so hung that the light sifts thru them, as in poplar and oak. The spruces and balsam fir have the remarkable power of growing slowly under heavy shade for many years, and then of growing vigorously when the light is let in by the fall of their overshadowing neighbors. This can plainly be seen in the cross-section of balsam fir, Fig. 63, where the narrow annual rings of the early growth, are followed by the wider ones of later growth. A common sight in the dense woods is the maple sending up a long, spindly stem thru the trees about it and having at its top a little tuft of leaves, Fig. 64. By so doing it survives. The fact that a tree can grow without shade often determines its possession of a burnt-over tract. The order in the North Woods after a fire is commonly, first, a growth of fire weed, then raspberries or blackberries, then aspen, a very intolerant tree whose light shade in turn permits under it the growth of the spruce, to which it is a "nurse," Fig. 65. In general it may be said that all seedling conifers require some shade the first two years, while hardwoods in temperate climates, as a rule, do not.

This matter of tolerance has also much to do with the branching of trees. The leaves on the lower branches of an intolerant tree will not thrive, with the result that those branches die and later drop off. This is called "cleaning," or natural pruning. Intolerant trees, like aspen and tulip, Fig. 66, clean themselves well and hence grow with long, straight boles, while tolerant trees, like spruce and fir, retain their branches longer.

The distribution of a species may also be determined by geographical barriers, like mountain ranges and oceans. This is why the western forests differ radically from the eastern forests and why the forest of Australasia is sharply distinct from any other forest in the world.

Any one or several of these factors, soil, moisture, heat, and light, may be the determining factor in the make-up of a forest, or it may be that a particular tree may survive, because of a faster rate of growth, thus enabling it to overtop its fellows and cut off their light. The struggle for survival is constant, and that tree survives which can take the best advantage of the existent conditions.

Besides these topographical and climatic factors which help determine the distribution of trees, a very important factor is the historical one. For example, the only reason by which the location of the few isolated groves of big trees in California can be accounted for is the rise and fall of glacial sheets, which left them, as it were, islands stranded in a sea of ice. As the glaciers retreated, the region gradually became re-forested, those trees coming up first which were best able to take advantage of the conditions, whether due to the character of their seeds, their tolerance, their endurance of moisture or whatever. This process is still going on and hardwoods are probably gaining ground.

Besides these external factors which determine the composition and organic life of the forest, the trees themselves furnish an important factor in their methods of reproduction. These, in general, are two, (1) by sprouts, and (2) by seeds.

(1) Most conifers have no power of sprouting. The chief exceptions are pitch pine and, to a remarkable degree, the redwood, Fig. 67. This power, however, is common in broad-leaved trees, as may be seen after a fire has swept thru second growth, hardwood timber. Altho all the young trees are killed down to the ground, the young sprouts spring up from the still living roots. This may happen repeatedly. Coppice woods, as of chestnut and oak, which sprout with great freedom, are the result of this ability. The wood is poor so that it is chiefly used for fuel.

(2) Most trees, however, are reproduced by seeds. Trees yield these in great abundance, to provide for waste,—nature's method. Many seeds never ripen, many perish, many are eaten by animals, many fall on barren ground or rocks, and many sprout, only to die. The weight of seeds has much to do with their distribution. Heavy seeds like acorns, chestnuts, hickory and other nuts, grow where they fall, unless carried down hill by gravity or by water, or scattered by birds and squirrels.

Trees with winged seeds, however, Fig. 68, as bass, maple and pine, or with light seeds, as poplar, often have their seeds carried by the wind to great distances.

Again some trees, as spruce, are very fertile, while others, like beech, have only occasional seed-bearing seasons, once in three or four years. Willow seeds lose their power of germination in a few days, and hence, unless they soon reach ground where there is plenty of moisture, they die. This is why they grow mostly along water courses. On the other hand, black locust pods and the cones of some pines keep their seeds perfect for many years, often until a fire bursts them open, and so they live at the expense of their competitors.

It is such facts as these that help to account for some of the acts of forest composition,—why in one place at one time there is a growth of aspens, at another time pines, at still another oaks; and why beeches spring up one year and not another. That red cedars grow in avenues along fences, is explained by the fact that the seeds are dropped there by birds, Fig. 69.

The fact that conifers, as the longleaf pine, Fig. 46, p. 200, and spruce, Fig. 55, p. 211, are more apt to grow in pure stands than broad-leaved trees, is largely accounted for by their winged seeds; whereas the broad-leaved trees grow mostly in mixed stands because their heavy seeds are not plentifully and widely scattered. This is a rule not without exceptions, for beech sometimes covers a whole mountain side, as Slide Mountain in the Catskills, and aspens come in over a wide area after a fire; but later other trees creep in until at length it becomes a mixed forest.

The essential facts of the relation of trees to each other in the forest has been clearly stated by Gifford Pinchot thus:¹

The history of the life of a forest is a story of the help and harm which trees receive from one another. On one side every tree is engaged in a relentless struggle against its neighbors for light, water and food, the three things trees need most. On the other side each tree is constantly working with all its neighbors, even those which stand at some distance, to bring about the best condition of the soil and air for the growth and fighting power of every other tree.

The trees in a forest help each other by enriching the soil in which they stand with their fallen leaves and twigs, which are not quickly blown or washed away as are those under a tree in the open. This collection of "duff" or "the forest floor" retains the moisture about their roots, and this moist mass tends to keep the temperature of the forest warmer in winter and cooler in summer. The forest cover, Fig. 55, p. 211, consisting largely of foliage, has the same effect, and in addition protects the bark, the roots, and the seedlings of the trees from the direct and continuous hot rays of the sun. Without the shade of the leaves, many trees, as white pine, would quickly die, as may readily be seen by transplanting them to the open. The mass of standing trees tempers the force of the wind, which might overthrow some of them, and hinders the drying up of the duff.

But trees hinder as well as help each other. There is a constant struggle between them for nourishment and light. To get food and water, some trees, as spruces and hemlocks, Fig. 70, spread their roots out flat; others, as oak and pine, send down a deep tap root. Those succeed in any environment that find the nourishment they need. Still more evident is the struggle for light and air. However well a tree is nourished thru its roots, unless its leaves have an abundance of light and air it will not thrive and make wood.

Even the trees most tolerant of shade in youth, like spruce, must have light later or perish, and hence in a forest there is the constant upward reach. This produces the characteristic "long-bodied" trunk of the forest tree, Fig. 71, in contrast to the "short-bodied" tree of the open, where the branches reach out in all directions, Fig. 72. In this constant struggle for existence is involved the persistent attempt of scattered seeds to sprout whenever there is an opening. The result is that a typical forest is one in which all sizes and ages of trees grow together. Scattered among these are bushes and scrubby trees, called "forest weeds," such as mountain maple and dogwood, Fig. 80, p. 233, which do not produce timber.