The Earth As Modified By Human Action Part 22

I suppose the quant.i.ties in the following estimates, from a carefully prepared article in the St. Louis Republican, must be understood as meaning square or superficial feet, board measure, allowing a thickness of one inch:

"The lumber trade of Michigan, Wisconsin, and Minnesota, for the year 1869, shows the amount cut as being 2,029,372,255 feet for the State of Michigan, and 317,400,000 feet for the State of Minnesota, and 964,600,000 feet for the State of Wisconsin. This includes the lake sh.o.r.e and the whole State of Wisconsin, which heretofore has been difficult to get a report from. The total amount cut in these States was 3,311,372,255 feet, and that to obtain this quant.i.ty there have been shipped 883,032 acres, or 1,380 square miles of pine have been removed.

It is calculated that 4,000,000 acres of land still remain unstripped in Michigan, which will yield 15,000,000,000 feet of lumber; while 3,000,000 acres arc still standing in Wisconsin, which will yield 11,250,000,000 feet, and that which remains in Minnesota, taking the estimate of a few years since of that which was surveyed and unexplored, after deducting the amount cut the past few years, we find 3,630,000 acres to be the proper estimate of trees now standing which will yield 32,362,500,000 feet of lumber. This makes a total of 15,630,000 acres of pine lands, which remain standing in the above States, that will yield 58,612,500,000 feet of lumber, and it is thought that fifteen or twenty years will be required to cut and send to market the trees now standing."

See also Bryant, Forest Trees, chap. iv.]

Effects of Forest Fires.

The operations of the lumberman involve other dangers to the woods besides the loss of the trees felled by him. The narrow clearings around his shanties form openings which let in the wind, and thus sometimes occasion the overthrow of thousands of trees, the fall of which dams up small streams, and creates bogs by the spreading of the waters, while the decaying trunks facilitate the multiplication of the insects which breed in dead wood and are, some of them, injurious to living trees. The escape and spread of camp-fires, however, is the most devastating of all the causes of destruction that find their origin in the operations of the lumberman. The proportion of trees fit for industrial uses is small in all primitive woods. Only these fall before the forester's axe, but the fire destroys, almost indiscriminately, every age and every species of tree. [Footnote: Trees differ in their power of resisting the action of forest fires. Different woods vary greatly in combustibility, and even when the bark is scarcely scorched, trees are, partly in consequence of physiological character, and partly from the greater or less depth at which their roots habitually lie below the surface, differently affected by running fires. The white pine, Pinus strobus, as it is the most valuable, is also perhaps the most delicate tree of the American forest, while its congener, the Northern pitch-pine, Pinus rigida, is less injured by fire than any other tree of that country. I have heard experienced lumbermen maintain that the growth of this pine was even accelerated by a fire brisk enough to destroy all other trees, and I have myself seen it still flourishing after a conflagration which had left not a green leaf but its own in the wood, and actually throwing out fresh foliage, when the old had been quite burnt off and the bark almost converted into charcoal. The wood of the pitch-pine is of comparatively little value for the joiner, but it is useful for very many purposes. Its rapidity of growth in even poor soils, its hardihood, and its abundant yield of resinous products, ent.i.tle it to much more consideration, as a plantation tree, than it has. .h.i.therto received in Europe or America.]

While, then, without fatal injury to the younger growths, the native forest will bear several "cuttings over" in a generation--for the increasing value of lumber brings into use, every four or five years, a quality of timber which had been before rejected as unmarketable--a fire may render the declivity of a mountain unproductive for a century.

[Footnote: Between sixty and seventy years ago, a steep mountain with which I am familiar, composed of metamorphic rock, and at that time covered with a thick coating of soil and a dense primeval forest, was accidentally burnt over. The fire took place in a very dry season, the slope of the mountain was too rapid to retain much water, and the conflagration was of an extraordinarily fierce character, consuming the wood almost entirely, burning the leaves and combustible portion of the mould, and in the many places cracking and disintegrating the rock beneath. The rains of the following autumn carried off much of the remaining soil, and the mountain-side was nearly bare of wood for two or three years afterwards. At length a new crop of trees sprang up and grew vigorously, and the mountain is now thickly covered again. But the depth of mould and earth is too small to allow the trees to reach maturity.

When they attain to the diameter of about six inches, they uniformly die, and this they will no doubt continue to do until the decay of leaves and wood on the surface, and the decomposition of the subjacent rock, shall have formed, perhaps hundreds of years hence, a stratum of soil thick enough to support a full-grown forest. Under favorable conditions, however, as in the case of the fire of Miramichi, a burnt forest renews itself rapidly and permanently.]

Aside from the destruction of the trees and the laying bare of the soil, and consequently the freer admission of sun, rain, and air to the ground, the fire of itself exerts an important influence on its texture and condition. It cracks and sometimes even pulverizes the rocks and stones upon and near the surface; [Footnote: In the burning over of a hill-forest in the Lower Engadine, in September, 1865, the fire was intense as to shatter and calcine the rocks on the slope, and their fragments were precipitated into the valley below.--Ricista Firrestate del Regna d'Italia, Ottobro, 1865, 1865, p. 474.] it consumes a portion of the half-decayed vegetable mould which served to hold its mineral particles together and to retain the water of precipitation, and thus loosens, pulverizes, and dries the earth; it destroys reptiles, insects, and worms, with their eggs, and the seeds of trees and of smaller plants; it supplies, in the ashes which it deposits on the surface, important elements for the growth of a new forest clothing, as well as of the usual objects of agricultural industry; and by the changes thus produced, it fits the ground for the reception of a vegetation different in character from that which had spontaneously covered it. These new conditions help to explain the natural succession of forest crops, so generally observed in all woods cleared by fire and then abandoned.

There is no doubt, however, that other influences contribute to the same result, because effects more or less a.n.a.logous follow when the trees are destroyed by other causes, as by high winds, by the woodman's axe, and even by natural decay. [Footnote: The remarkable mounds and other earthworks constructed in the valley of the Ohio and elsewhere in the territory of the United States, by a people apparently more advanced in the culture than the modern Indian, were overgrown with a dense clothing of forest when first discovered by the whites. But though the ground where they were erected must have been occupied by a large population for a considerable leagth of time, and therefore entirely cleared, the trees which grew upon the ancient fortresses and the adjacent lands were not distinguishable in species, or even in dimensions and character of growth, from the neighboring forests, where the soil seemed never to have been disturbed. This apparent exception to the law of change of crop in natured forest growth was ingeniously explained by General Harrison's suggestion, that the lapse of time since the era of the mound-builders was so great as to have embraced several successive generations of trees, and occasioned, by their rotation, a return to the original vegetation.

The succesive changes in the spontaneous growth of the forest, as proved by the character of the wood found in bogs, are such as to have suggested the theory of a considerable change of climate during the human period. But strobus, as it is the most valuable, is also perhaps the most delicate tree of the American forest, while its congener, the Northern pitch-pine, Pinus rigida, is less injured by fire than any other tree of that country. I have heard experienced lumbermen maintain that the growth of this pine was even accelerated by a fire brisk enough to destroy all other trees, and I have myself seen it still flourishing after a conflagration which had left not a green leaf but its own in the wood, and actually throwing out fresh foliage, when the old had been quite burnt off and the bark almost converted into charcoal. The wood of the pitch-pine is of comparatively little value for the joiner, but it is useful for very many purposes. Its rapidity of growth in even poor soils, its hardihood, and its abundant yield of resinous products, ent.i.tle it to much more consideration, as a plantation tree, than it has. .h.i.therto received in Europe or America.] without fatal injury to the younger growths, the native forest will hear several "cuttings over" in a generation--for the increasing value of lumber brings into use, every four or five years, a quality of timber which had been before rejected as unmarketable--a fire may render the declivity of a mountain unproductive for a century. [Footnote: Between sixty and seventy years ago, a steep mountain with which I am familiar, composed of metamorphic rock, and at that time covered with a thick coating of soil and a dense primeval forest, was accidentally burnt over. The fire took place in a very dry season, the slope of the mountain was too rapid to retain much water, and the conflagration was of an extraordinarily fierce character, consuming the wood almost entirely, burning the leaves and combustible portion of the mould, and in many places cracking and disintegrating the rock beneath. The rains of the following autumn carried off much of the remaining soil, and the mountain-side was nearly bare of wood for two or three years afterwards. At length a new crop of trees sprang up and grew vigorously, and the mountain is now thickly covered again. But the depth of mould and earth is too small to allow the trees to reach maturity.

When they attain to the diameter of about six inches, they uniformly die, and this they will no doubt continue to do until the decay of leaves and wood on the surface, and the decomposition of the subjacent rock, shall have formed, perhaps hundreds of years hence, a stratum of soil thick enough to support a full-grown forest. Under favorable conditions, however, as in the case of the fire of Miramichi, a burnt forest renews itself rapidly and permanently.]

Aside from the destruction of the trees and the laying bare of the soil, and consequently the freer admission of sun, rain, and air to the ground, the fire of itself exerts an important influence on its texture and condition. It cracks and sometimes even pulverizes the rocks and stones upon and near the surface; [Footnote: In the burning over of a hill-forest in the Lower Engadine, in September, 1865, the fire was so intense as to shatter and calcine the rocks on the slope, and their fragments were precipitated into the valley below.--Rivista Forestale del Regno d'Italia, Ottobre, 1865, p. 474.] it consumes a portion of the half-decayed vegetable mould which served to hold its mineral particles together and to retain the water of precipitation, and thus loosens, pulverizes, and dries the earth; it destroys reptiles, insects, and worms, with their eggs, and the seeds of trees and of smaller plants; it supplies, in the ashes which it deposits on the surface, important elements for the growth of a new forest clothing, as well as of the usual objects of agricultural industry; and by the changes thus produced, it fits the ground for the reception of a vegetation different in character from that which had spontaneously covered it. These new conditions help to explain the natural succession of forest crops, so generally observed in all woods cleared by fire and then abandoned.

There is no doubt, however, that other influences contribute to the same result, because effects more or less a.n.a.logous follow when the trees are destroyed by other causes, as by high winds, by the woodman's axe, and even by natural decay. [Footnote: The remarkable mounds and other earthworks constructed in the valley of the Ohio and elsewhere in the territory of the United States, by a people apparently more advanced in culture than the modern Indian, were overgrown with a dense clothing of forest when first discovered by the whites. But though the ground where they were erected must have been occupied by a large population for a considerable length of time, and therefore entirely cleared, the trees which grew upon the ancient fortresses and the adjacent lands were not distinguishable in species, or even in dimensions and character of growth, from the neighboring forests, where the soil seemed never to have been disturbed. This apparent exception to the law of change of crop in natural forest growth was ingeniously explained by General Harrison's suggestion, that the lapse of time since the era of the mound-builders were so great as to have embraced several successive generations of trees, and occasioned, by their rotation, a return to the original vegetation.

The successive changes in the spontaneous growth of the forest, as proved by the character of a wood found in bogs, are such as to have suggested the theory of a considerable change of the climate during the human period. But this theory cannot be admitted upon the evidence in question. In fact, the order of succession--for a rotation or alternation is neither proved nor probable--may be made to move in opposite directions in different countries with the same climate and at the same time. Thus in Denmark and in Holland the spike-leaved firs have given place to the broad-leaved beech, while in Northern Germany the process has been reversed, and evergreens have supplanted the oaks and birches of deciduous foliage. The princ.i.p.al determining cause seems to be the influence of light upon the germination of the seeds and the growth of the young tree. In a forest of firs, for instance, the distribution of the light and shade, to the influence of which seeds and shoots are exposed, is by no means the same as in a wood of beeches or of oaks, and hence the growth of different species will be stimulated in the two forests.

When ground is laid bare both of trees and of vegetable mould, and left to the action of unaided and un.o.bstructed nature, she first propagates trees which germinate and grow only under the influence of a full supply of light and air, and then, in succession, other species, according to their ability to bear the shade and their demand for more abundant nutriment. In Northern Europe the large, the white birch, the aspen, first appear; then follow the maple, the alder, the ash, the fir; then the oak and the linden; and then the beech. The trees called by these respective names in the United States are not specifically the same as their European namesakes, nor are they always even the equivalents of these latter, and therefore the order of succession in America would not be precisely as indicated by the foregoing list, but, so far as is known, it nevertheless very nearly corresponds to it.

It is thought important to encourage the growth of the beech in Denmark and Northern Germany, because it upon the whole yields better returns than other trees, and does not exhaust, but on the contrary enriches, the soil; for by shedding its leaves it returns to it most of the nutriment it has drawn from it, and at the same time furnishes a solvent which aids materially in the decomposition of its mineral const.i.tuents.

When the forest is left to itself, the order of succession is constant, and its occasional inversion is always explicable by some human interference. It is curious that the trees which require most light are content with the poorest soils, and vice versa. The trees which first appear are also those which propagate themselves farthest to the north.

The birch, the larch, and the fir bear a severer climate than the oak, the oak than the beech. "These parallelisms," says Vaupell, "are very interesting, because, though they are entirely independent of each other," they all prescribe the same order of succession.--Bogens Indvandring, p. 42. See alo Berg, Das Verdrangen der Laubralder im Nordlichen Deutschland, 1844. Heyer, Das Verhalten der Waldbaume gegen Licht und Schatten, 1852. Staring, De Bodem van Nederland, 1856, i., pp.

120-200. Vaupell, De Danske Skove, 1863. Knorr, Studien uber die Buchen-Wirthschaft, 1863. A. Maury, Les Forets de la Gaule, pp. 73, 74, 377, 384.]

Another evil, sometimes of serious magnitude, which attends the operations of the lumberman, is the injury to the banks of rivers from the practice of floating. I do not here allude to rafts, which, being under the control of those who navigate them, may be so guided as to avoid damage to the sh.o.r.e, but to masts, logs, and other pieces of timber singly entrusted to the streams, to be conveyed by their currents to sawmill ponds, or to convenient places for collecting them into rafts. The lumbermen usually haul the timber to the banks of the rivers in the winter, and when the spring floods swell the streams and break up the ice, they roll the logs into the water, leaving them to float down to their destination. If the transporting stream is too small to furnish a sufficient channel for this rude navigation, it is sometimes dammed up, and the timber collected in the pond thus formed above the dam. When the pond is full, a sluice is opened, or the dam is blown up or otherwise suddenly broken, and the whole ma.s.s of lumber above it is hurried down with the rolling flood. Both of these modes of proceeding expose the banks of the rivers employed as channels of flotation to abrasion, [Footnote: Caimi states that "a single flotation in the Valtelline, in 1830, caused damages appraised at $250,000."--Cenni sulla Importanza e Coltura dei Boschi, p. 65.] and in some of the American States it has been found necessary to protect, by special legislation, the lands through which they flow from the serious injury sometimes received through the practices I have described. [Footnote: Many physicists who have investigated the laws of natural hydraulics maintain that, in consequence of direct obstruction and frictional resistance to the flow of the water of rivers along their banks, there is both an increased rapidity of current and an elevation of the water in the middle of the channel, so that a river presents always a convex surface.

Others have thought that the acknowledged greater swiftness of the central current must produce a depression in that part of the stream.

The lumbermen affirm that, while rivers are rising, the water is highest in the middle of the channel, and tends to throw floating objects sh.o.r.ewards; while they are falling, it is lowest in the middle, and floating objects incline towards the centre. Logs, they say, rolled into the water during the rise, are very apt to lodge on the banks, while those set afloat during the falling of the waters keep in the current, and are carried without hindrance to their destination, and this law, which has been a matter of familiar observation among woodmen for generations, is now admitted as a scientific truth.

Foresters and lumbermen, like sailors and other persons whose daily occupations bring them into contact, and often into conflict, with great natural forces, have many peculiar opinions, not to say superst.i.tious.

In one of these categories we must rank the universal belief of lumbermen, that with a given head of water, and in a given number of hours, a sawmill cuts more lumber by night than by day. Having been personally interested in several sawmills, been a.s.sured by them that their uniform experiences established the fact that, other things being equal, the action of the machinery of sawmills is more rapid by night than by day. I am sorry--perhaps I ought to be ashamed--to say that my skepticism has been too strong to allow me to avail myself of my ooportunites of testing this question by pa.s.sing a night, watch in hand, counting the strokes of a millisaw. More unprejudiced, and, I must add, very intelligent and credible persons have informed me that they have done so, and found the report of the sawyers abundantly confirmed. A land surveyor, who was also an experienced lumberman, sawyer, and machinist, a good mathematician, and an accurate observer, has repeatedly told me that he had very often "timed" sawmills, and before the difference in favor of night-work above thirty per cent. Sed quaere.]

Restoration of the Forest.

In most countries of Europe--and I fear in many parts of the United States--the woods are already so nearly extirpated, that the mere protection of those which now exist is by no means an adequate security against a great increase of the evils which have already resulted from the diminution of them. Besides this, experience has shown that where the destruction of the woods has been carried beyond a certain point, no coercive legislation can absolutely secure the permanence of the remainder, especially if it is held by private hands. The creation of new forests, therefore, is generally recognized, wherever the subject has received the attention it merits, as an indispensable measure of sound public economy. Enlightened individuals in some European states, the Governments in others, have made extensive plantations, and France, particularly, has now set herself energetically at work to restore the woods in her southern provinces, and thereby to prevent the utter depopulation and waste with which that once fertile soil and genial climate are threatened.

The objects of the restoration of the forest are as multifarious as the motives that have led to its destruction, and as the evils which that destruction has occasioned. It is hoped that the replanting of the mountain slopes, and of bleak and infertile plains, will diminish the frequency and violence of river inundations, prevent the formation of new torrents and check the violence of those already existing, mitigate the extremes of atmospheric temperature, humidity, and precipitation, restore dried-up springs, rivulets, and sources of irrigation, shelter the fields from chilling and from parching winds, arrest the spread of miasmatic effluvia, and, finally, furnish a self-renewing and inexhaustible supply of a material indispensable to so many purposes of domestic comfort, and to the successful exercise of every art of peace, every destructive energy of war. [Footnote: The preservation of the woods on the former eastern frontier of France, as a kind of natural abattis, was recognized by the Government of that country as an important measure of military defence, though there have been conflicting opinions on the subject.]

The Economy of the Forest.

The legislation of European states upon sylviculture, and the practice of that art, divide themselves into two great branches--the preservation of existing forests, and the creation of new. Although there are in Europe many forests neither planted nor regularly trained by man, yet from the long operation of causes already set forth, what is understood in America and other new countries by the "primitive forest," no longer exists in the territories which were the seats of ancient civilization and empire, except upon a small scale, and in remote and almost inaccessible glens quite out of the reach of ordinary observation. The oldest European woods are indeed native, that is, sprung from self-sown seed, or from the roots of trees which have been felled for human purposes; but their growth has been controlled, in a variety of ways, by man and by domestic animals, and they almost uniformly present more or less of an artificial character and arrangement. Both they and planted forests--which, though certainly not few, are of comparatively recent date in Europe--demand, as well for protection as for promotion of growth, a treatment different in some respects from that which would be suited to the character and wants of the virgin wood.

On this latter branch of the subject, the management of the primitive wood, experience and observation have not yet collected a sufficient stock of facts to serve for the construction of a complete system of this department of sylviculture; but the government of the forest as it exists in France--the different zones and climates of which country present many points of a.n.a.logy with those of the United States and of some of the British colonies--has been carefully studied, and several manuals of practice have been prepared for the foresters of that empire.

I believe the Cours Elementaire de Culture des Bois cree a l'Ecole Forestiere de Nancy, par M. Lorentz, complete et public par A. Parade, with a supplement under the t.i.tle of Cours d'Amenagement des Forets, par Henri Nanquette, has been generally considered the best of these. The Etudes sur l'Economie Forestiere, par Jules Clave, which I have often quoted, presents a great number of interesting views on this subject, but it is not designed as a practical guide, and it does not profess to be sufficiently specific in its details to serve that purpose. [Footnote: Among more recent manuals may be mentioned: in French, Les Etudes de Maitre Pierre, Paris, 1864, 12mo; Bazelaire, Traite de Robois.e.m.e.nt, 2d edition. Paris 1864; Paston, L'Amenagemend des Forets, Paris, 1867; in English, Gregor, Arboriculture, Edinburgh, 1868: in Italian, Siemoni 's very valuable Manuale teorico-pratico d'Arte Forestale, 2d ediz., Firenze, 1872; the excellent work of Cerini, Dei Vantaggi di Societe, por l'Impianto e Conservazione dei Boschi, Milano, 1844, 8vo; and the prize essay of Meguscher, Memoria sui Boschi, etc., 2d edizione, Milano, 1859, 8vo. Another very important treatise of the uses of the forest, though not a manual of sylviculture, is Schleiden, Fur Baum und Wald, Leipzig, 1870.]Notwithstanding the difference of conditions between the aboriginal and the trained forest, the judicious observer who aims at the preservation of the former will reap much instruction from the treatises I have cited, and I believe he will be convinced that the sooner a natural wood is brought into the state of an artificially regulated one, the better it is for all the multiplied interests which depend on the wise administration of this branch of public economy.

One consideration bearing on this subject has received less attention than it merits, because most persons interested in such questions have not opportunities for the comparison I refer to. I mean the great general superiority of cultivated timber to that of strictly spontaneous growth. I say GENERAL superiority, because there are exceptions to the rule. The white pine, Pinus strobus, for instance, and other trees of similar character and uses, require, for their perfect growth and best ligneous texture, a density of forest vegetation around them, which protects them from too much agitation by wind, and from the persistence of the lateral branches which fill the wood with knots. A pine which has grown under those conditions possesses a tall, straight stem, admirably fitted for masts and spars, and, at the same time, its wood is almost wholly free from knots, is regular in annular structure, soft and uniform in texture, and, consequently, superior to almost all other timber for joinery. If, while a large pine is spared, the broad-leaved or other smaller trees around it are felled, the swaying of the tree from the action of the wind mechanically produces separations between the layers of annual growth, and greatly diminishes the value of the timber. The same defect is often observed in pines which, from some accident of growth, have much overtopped their fellows in the virgin forest.

The white pine, growing in the fields, or in open glades in the woods, is totally different from the true forest-tree, both in general aspect and in quality of wood. Its stem is much shorter, its top less tapering, its foliage denser and more inclined to gather into tufts, its branches more numerous and of larger diameter, its wood shows much more distinctly the divisions of annual growth, is of coa.r.s.er grain, harder and more difficult to work into mitre-joints. Intermixed with the most valuable pines in the American forests, are met many trees of the character I have just described. The lumbermen call them "saplings," and generally regard them as different in species from the true white pine, but botanists are unable to establish a distinction between them, and as they agree in almost all respects with trees grown in the open grounds from known white-pine seedlings, I believe their peculiar character is due to unfavorable circ.u.mstances in their early growth. The pine, then, is an exception to the general rule as to the inferiority of the forest to the open-ground tree. The pasture oak and pasture beech, on the contrary, are well known to produce far better timber than those grown in the woods, and there are few trees to which the remark is not equally applicable. [Footnote: It is often laid down as a universal law, that the wood of trees of slow vegetation is superior to that of quick growth.

This is one of those commonplaces by which men love to shield themselves from the labor of painstaking observation. It has, in fact, so many exceptions, that it may be doubted in whether it is in any sense true.

Most of the cedars are slow of growth; but while the timber of some of them is firm and durable, that of others is light, brittle, and perishable. The hemlock-spruce is slower of growth than the pines, but its wood is of very little value. The pasture oak and beech show a breadth of grain--and, of course, an annual increment--twice as great as trees of the same species grown in the woods; and the American locust, Robinia pseudacacia, the wood of which is of extreme toughness and durability, is, of all trees indigenous to North-eastern America, by far the most rapid in growth. Some of the species of the Australian Eucalyptus furnish wood of remarkable strength and durability, and yet the eucalyptus is surpa.s.sed by no known tree in rapidity of growth.

As an ill.u.s.tration of the mutual interdependence of the mechanic arts, I may mention that in Italy, where stone, brick, and plaster are almost the only materials used in architecture, and where the "hollow ware"

kitchen implements are of copper or of clay, the ordinary tools for working wood are of a very inferior description, and the locust timber is found too hard for their temper. At the same time the work of the Italian stipettai, or cabinet-makers, and carvers in wood, who take pains to provide themselves with tools of better metal, is wholly unsurpa.s.sed in finish and in accuracy of adjustment as well as in taste.

When a small quant.i.ty of mahogany was brought to England, early in the last century, the cabinet-makers were unable to use it, from the defective temper of their tools, until the demand for furniture from the new wood compelled them to improve the quality of their implements. In America, the cheapness of wood long made it the preferable material for almost all purposes to which it could by any possibility be applied. The mechanical cutlery and artisans' tools of the United States are of admirable temper, finish, and convenience, and no wood is too hard, or otherwise too refractory, to be wrought with great facility, both by hand-tools and by the mult.i.tude of ingenious machines which the Americans have invented for this purpose.]

Another advantage of the artificially regulated forest is, that it admits of such grading of the ground as to favor the retention or discharge of water at will, while the facilities it affords for selecting and duly proportioning, as well as properly s.p.a.cing, and in felling and removing, from time to time, the trees which compose it, are too obvious to require to be more than hinted at. In conducting these operations, we must have a diligent eye to the requirements of nature, and must remember that a wood is not an arbitrary a.s.semblage of trees to be selected and disposed according to the caprice of its owner. "A forest," says Clave, "is not, as is often supposed, a simple collection of trees succeeding each other in long perspective, without bond of union, and capable of isolation from each other; it is, on the contrary, a whole, the different parts of which are interdependent upon each other, and it const.i.tutes, so to speak, a true individuality. Every forest has a special character, determined by the form of the surface it grows upon, the kinds of trees that compose it, and the manner in which they are grouped." The art, or, as the Continental foresters rather ambitiously call it, the science of sylviculture has been so little pursued in England and America, that its nomenclature has not been introduced into the English vocabulary, and it would not be possible to describe its processes with technical propriety of language, without occasionally borrowing a word from the forest literature of France and Germany. A full discussion of the methods of sylviculture would, indeed, be out of place in a work like the present, but the want of conveniently accessible means of information on the subject, in the United States, will justify me in presenting it with somewhat more of detail than would otherwise be pertinent.

The two best known methods of treating already existing forests are those distinguished as the TAILLIS, copse or coppice treatment, [Footnote: COPSE, or COPPICE, from the French COUPER, to cut, means properly a wood, the trees of which are cut at certain periods of immature growth, and allowed to shoot up again from the roots; but it has come to signify, very commonly, a young wood, grove, or thicket, without reference to its origin, or to the character of a forest crop.]

and the FUTAIE, for which I find no English equivalent, but which may not inappropriately be called the FULL-GROWTH system. A TAILLIS, copse, or coppice, is a wood composed of shoots from the roots of trees previously cut for fuel and timber. The shoots are thinned out from time to time, and finally cut, either after a fixed number of years, or after the young trees have attained to certain dimensions, their roots being then left to send out a new progeny as before. This is the cheapest method of management, and therefore the best whenever the price of labor and of capital bears a high proportion to that of land and of timber; but it is essentially a wasteful economy. [Footnote: "In America," says Clave (p. 124, 125), "where there is a vast extent of land almost without pecuniary value, but where labor is dear and the rate of interest high, it is profitable to till a large surface at the least possible cost. EXTENSIVE cultivation is there the most advantageous. In England, France, and Germany, where every corner of soil is occupied, and the least bit of ground is sold at a high price, but where labor and capital are comparatively cheap is wisest to employ INTENSIVE cultivation. ... All the efforts of the cultivator ought to be directed to the obtaining of a given result with the least sacrifice, and there is equally a loss to the commonwealth if the application of improved agricultural processes be neglected where they are advantageous, or if they be employed where they are not required. ... In this point of view, sylviculture must follow the same laws as agriculture, and, like it, be modified according to the economical conditions of different states. In countries abounding in good forests, and thinly peopled, elementary and cheap methods must be pursued; in civilized regions, where a dense population requires that the soil shall be made to produce all it can yield, the regular artificial forest, with all the processes that science teaches, should be cultivated. It would be absurd to apply to the endless woods of Brazil and of Canada the method of the Spessart by "double stages," but not less so in our country, where every yard of ground has a high value, to leave to nature the task of propagating trees, and to content ourselves with cutting, every twenty or twenty-five years, the meagre growths that chance may have produced."]

If the woodland is, in the first place, completely cut over as is found most convenient in practice, the young shoots have neither the shade nor the protection from wind so important to forest growth, and their progress is comparatively slow, while at the same time, the thick clumps they form choke the seedlings that may have sprouted near them.

[Footnote: In ordinary coppices, there are few or no seedlings, because the young shoots are cut before they are old enough to mature fertile seed, and this is one of the strongest objections to the system.] The evergreens, once cut do not shoot up again, [Footnote: It was not long ago stated, upon the evidence of the Government foresters of Greece, and of the queen's gardener, that a large wood has been discovered in Arcadia, consisting of a fir which has the property of sending up both vertical and lateral shoots from the stump of felled trees and forming a new crown. It was at first supposed that this forest grew only on the "mountains," of which the hero of About's most amusing story, Le Roi des Montagnes, was "king;" but stumps, with the shoots attached, have been sent to Germany, and recognized by able botanists as true natural products, and the fact must now be considered as established. Daubeny refers to Theophrastus as ascribing this faculty of reproduction to the 'Elate [word in greek] or fir, but he does not cite chapter and verse, and I have not been able to find the pa.s.sage. The same writer mentions a case where an entire forest of the common fir in France had been renewed in this way.--Trees and Shrubs of the Ancients, 1865, pp. 27-28. The American Northern pitch possesses the same power in a certain degree.

According to Charles Martins, the cedar of Mount Atlas--which, if not identical with the cedar of Lebanon, is closely allied to it--possesses the same power.--Revue des Deux Mondes, July 15, 1864, p. 315.] and the mixed character of the forest--in many respects an important advantage, if not an indispensable condition of growth--is lost; [Footnote: Natural forests are rarely, if ever, composed of trees of a single species, and experience has shown that oaks and other broad-leaved trees, planted as artificial woods, require to be mixed, or a.s.sociated with others of different habits.

In the forest of Fontainebleau, "oaks, mingled with beeches in due proportion," says Clave, "may arrive at the age of five or six hundred years in full vigor, and attain dimensions which I have never seen surpa.s.sed; when, however, they are wholly unmixed with other trees, they begin to decay and die at the top, at the age of forty or fifty years, like men, old before their time, weary of the world, and longing only to quit it. This has been observed in most of the oak plantations of which I have spoken, and they have not been able to attain to full growth.

When the vegetation was perceived to languish, they were cut, in the hope that this operation would restore their vigor, and that the new shoots would succeed better than the original trees; and, in fact, they seemed to be recovering for the first few years. But the shoots were soon attacked by the same decay, and the operation had to be renewed at shorter and shorter intervals, until at last it was found necessary to treat as coppices plantations originally designed for the full-growth system. Nor was this all: the soil, periodically bared by these cuttings, became impoverished, and less and less suited to the growth of the oak. ... It was then proposed to introduce the pine and plant with it the vacancies and glades.

"... By this means, the forest was saved from the ruin which threatened it, and now more than 10,000 acres of pines, from fifteen to thirty years old are disseminated at various points, sometimes intermixed with broad-leaved trees, sometimes forming groves by themselves"--Revue des Deux Mondes, Mai, 1863, pp. 153, 154.] and besides this, large wood of any species cannot be grown in this method because trees which shoot from decaying stumps and their dying roots, become hollow or otherwise unsound before they acquire their full dimensions. A more fatal objection still, is, that the roots of trees will not bear more than two or three, or at most four cuttings of their shoots before their vitality is exhausted, and the wood can then be restored only by replanting entirely.

The period of cutting coppices varies in Europe from fifteen to forty years, according to soil, species, and rapidity of growth. In the futaie, or full-growth system, the trees are allowed to stand as long as they continue in healthy and vigorous growth. This is a shorter period than would be at first supposed, when we consider the advanced age and great dimensions to which, under favorable circ.u.mstances, many forest-trees attain in temperate climates. But, as every observing person familiar with the forest is aware, these are exceptional cases, just as are instances of great longevity or of gigantic stature among men. Able vegetable physiologists have maintained that the tree, like most fish and reptiles, has no natural limit of life or of growth, and that the only reason why our oaks and our pines do not reach the age of twenty centuries and the height of a hundred fathoms, is, that in the mult.i.tude of accidents to which they are exposed, the chances of their attaining to such a length of years and to such dimensions of growth are millions to one against them. But another explanation of this fact is possible. In trees affected by no discoverable external cause of death, decay begins at the topmost branches, which seem to wither and die for want of nutriment. The mysterious force by which the sap is carried from the roots to the utmost twigs, cannot be conceived to be unlimited in power, and it is probable that it differs in different species, so that while it may suffice to raise the fluid to the height of five hundred feet in the eucalyptus, it may not be able to carry it beyond one hundred and fifty in the oak. The limit may be different, too, in different trees of the same species, not from defective organization in those of inferior growth, but from more or less favorable conditions of soil, nourishment, and exposure. Whenever a tree attains to the limit beyond which its circulating fluids cannot rise, we may suppose that decay begins, and death follows from want of nutrition at the extremities, and from the same causes which bring about the same results in animals of limited size--such, for example, as the interruption of functions essential to life, in consequence of the clogging up of ducts by matter a.s.similable in the stage of growth, but no longer so when increment has ceased. In the natural woods we observe that, though, among the myriads of trees which grow upon a square mile, there are several vegetable giants, yet the great majority of them begin to decay long before they have attained their maximum of stature, and this seems to be still more emphatically true of the artificial forest. In France, according to Clave, "oaks, in a suitable soil, may stand, without exhibiting any sign of decay, for two or three hundred years; the pines hardly exceed one hundred and twenty, and the soft or white woods [bois blancs], in wet soils, languish, and die before reaching the fiftieth year." [Footnote: Etudes Forestieres, p. 80.] These ages are certainly below the average of those of American forest-trees, and are greatly exceeded in very numerous well-attested instances of isolated trees in Europe.

The former mode of treating the futaie, called the garden system, was to cut the trees individually as they arrived at maturity, but, in the best regulated forests, this practice has been abandoned for the German method, which embraces not only the securing of the largest immediate profit, but the replanting of the forest, and the care of the young growth. This is effected in the case of a forest, whether natural or artificial, which is to be subjected to regular management, by three operations. The first of these consists in felling about one-third of the trees, in such way as to leave convenient s.p.a.ces for the growth of seedlings. The remaining two-thirds are relied upon to replant the vacancies, by natural sowing, which they seldom or never fail to do. The seedlings are watched, are thinned out when too dense, and the ill-formed and sickly, as well as those of species of inferior value, and the shrubs and thorns which might otherwise choke or too closely shade them, are pulled up. When they have attained sufficient strength and development of foliage to require, or at least to bear, more light and air, the second step is taken, by removing a suitable proportion of the old trees which had been spared at the first cutting; and when, finally, the younger trees are hardened enough to bear frost and sun without other protection than that which they mutually give to each other, the remainder of the original forest is felled, and the wood now consists wholly of young and vigorous trees. This result is obtained after about twenty years. At convenient periods, the unhealthy stocks and those injured by wind or other accidents are removed, and in some instances the growth of the remainder is promoted by irrigation or by fertilizing applications. [Footnote: The grounds which it is most important to clothe with wood as a conservative influence, and which, also, can best be spared from agricultural use, are steep hillsides. But the performance of all the offices of the forester to the tree--seeding, planting, thinning, tr.i.m.m.i.n.g, and finally felling and removing for consumption--is more laborious upon a rapid declivity than on a level soil, and at the same time it is difficult to apply irrigation or manures to trees so situated. Experience has shown that there in great advantage in terracing the face of a hill before planting it, both as preventing the wash of the earth by checking the flow of water down its slope, and as presenting a surface favorable for irrigation, as well as for manuring and cultivating the tree. But even without so expensive a process, very important results have been obtained by simply ditching declivities. "In order to hasten the growth of wood on the flanks of a mountain, Mr. Eugene Chevandier divided the slope into zones forty or fifty feet wide, by horizontal ditches closed at both ends, and thereby obtained, from firs of different ages, shoots double the dimensions of those which grew on a dry soil of the same character, where the water was allowed to run off without obstruction."--Dumont, Des Travaux Publics, etc., pp. 94-96. The ditches were about two feet and a half deep, and three feet and a half wide, and they cost about forty francs the hectare, or three dollars the acre. This extraordinary growth was produced wholly by the retention of the rain-water in the ditches, whence it filtered through the whole soil and supplied moisture to the roots of the trees. It may be doubted whether in a climate cold enough to freeze the entire contents of the ditches in winter, it would not be expedient to draw off the water in the autumn, as the presence of so large a quant.i.ty of ice in the soil might prove injurious to trees too young and small to shelter the ground effectually against frost.

Chevandier computes that, if the annual growth of the pine in the marshy and too humid soil of the Vosges be represented by one, it will equal two in ordinary dry ground, four or five on slopes so ditched or graded as to retain the water flowing upon them from roads or steep declivities, and six where the earth is kept sufficiently moist by infiltration from running brooks.--Comptes Rendus a l'Academie des Sciences, t. xix., Juillet, Dec., 1844, p. 167. The effect of accidental irrigation in well shown in the growth of the trees planted along the ca.n.a.ls of irrigation which traverse the fields in many parts of Italy.

They nourish most luxuriantly, in spite of continual lopping, and yield a very important contribution to the stock of fuel for domestic use while trees, situated so far from ca.n.a.ls as to be out of the reach of infiltration from them, are of much slower growth, under circ.u.mstances otherwise equally favorable. In other experiments of Chevandier, under better conditions, the yield of wood was increased, by judicious irrigation, in the ratio of seven to one, the profits in that of twelve to one. At the Exposition of 1855, Chambrelent exhibited young trees, which, in four years from the seed, had grown to the height of sixteen and twenty feet, and the circ.u.mference of ten and twelve inches.

Chevandier experimented with various manures, and found that some of them might be profitably applied to young but not to old trees, the quant.i.ty required in the latter case being too great. Wood-ashes and the refuse of soda factories are particularly recommended. See, on the manuring of trees, Chevandier, Recherches sur l'emploi de divers amendements, etc., Paris, 1852, and Koderle, Grundsatze der Kunstlichen Dungung im Forstculturwesen. Wien, 1865.

I have seen an extraordinary growth produced in fir-trees by the application of soapsuds; in a young and sickly cherry-tree, by heaping the chips and dust from a marble-quarry, to the height of two or three feet, over the roots and around the stem; and cases have come to my knowledge where like results followed the planting of vines and trees in holes half filled with fragments of plaster-castings, and mortar from old buildings. Chevandier's experiments in the irrigation of the forest would not have been a "new thing under the sun" to wise King Solomon, for that monarch saya: "I made me pools of water, to water therewith, the wood that bringeth forth trees." Eccles. ii. 6.]

When the forest is approaching maturity, the original processes already described are repeated; and as, in different parts of an extensive forest, they would take place at different times in different zones, it would afford indefinitely an annual crop of small wood, fuel, and timber.

The duties of the forester do not end here, for it sometimes happens that the glades left by felling the older trees are not sufficiently seeded, or that the species, or essences, as the French oddly call them, are not duly proportioned in the new crop. In this case, seed must be artificially sown, or young trees planted in the vacancies. Besides this, all trees, whether grown for fruit, for fuel, or for timber, require more or less training in order to yield the best returns. The experiments of the Vicomte de Courval in sylviculture throw much light on this subject, and show, in a most interesting way, the importance of pruning forest-trees. The princ.i.p.al feature of De Courval's very successful method is a systematical mode of tr.i.m.m.i.n.g which compels the tree to develop the stem, by reducing the lateral ramification.

Beginning with young trees, the buds are rubbed off from the stems, and superfluous lateral shoots are pruned down to the trunk. When large trees are taken in hand, branches which can be spared, and whose removal is necessary to obtain a proper length of stem, are very smoothly cut off quite close to the trunk, and the exposed surface is IMMEDIATELY brushed over with mineral-coal tar. When thus treated, it is said that the healing of the wound is perfect, and without any decay of the tree.

Trees trained by De Courval's method, which is now universally approved and much practised in France, rapidly attained a great height. They grow with remarkable straightness of stem and of grain, and their timber commands the highest price. [Footnote: See De Courval, Taille et conduite des Arbres forestieres et autres arbres de grande dimension.

Paris, 1861.

The most important part of Viscount de Courval's system will be found in L'Elagage des Arbres, par le Comte A. Des Cars, an admirable little treatise, of which numerous editions, at the price of one franc, have been printed since the first, of 1864, and which ought to be translated and published without delay in the United States.]

A system of plantation, specially though not exclusively suited to very moist soils, recommended by Duhamel a hundred years ago, has been revived in Germany, within about twenty years, with much success. It is called hill-planting, and consists in placing the young tree upright on the greensward with its roots properly spread out, and then covering the roots and supporting the trunk by thick sods cut so as to form a circular hillock around it. [Footnote: See Manteuffel, L'Art de Planter, traduit par Stumper. Paris, 1868.] By this method it is alleged trees can be grown advantageously both in dry ground and on humid soils, where they would not strike root if planted in holes after the usual mauner.