North America

Of still more lowly habits are the ferns, mosses, and lichens which form a thick, luxuriant, and ever-varied carpet over the black humus soil beneath. The ground throughout the forest is encumbered with fallen trunks, sometimes piled one on another to the depth of 20 or 30 feet, which, owing to the continuous moisture, remain undecayed for centuries. Not infrequently a massive cedar or fir, in size and shape not unlike a prostrate column of some great temple, supports three or more trees, each large enough to be cut for lumber, whose gnarled and twisted roots clasp the sides of their host and descend to the earth beneath. The beauty of these fallen giants when overgrown with thick layers of variegated moss and exquisitely decorated with hundreds of small hemlocks and a multitude of gracefully bending fern-fronds, always fresh in colour and usually beaded with moisture, is beyond the power of the most skilful artist to adequately portray. The fascination of the great forest is such that the explorer, although perhaps weary with forcing a passage through the dense undergrowths and climbing over prostrate trunks, is lured by its charms into more and more inaccessible retreats probably never before invaded by man, but at last finding that the wonderland has no attainable limits, is content to rest on some inviting couch of golden-tinted lichens and study the varied charms and endless details of the dream-like picture surrounding him.

From a commercial point of view the forest of the Puget Sound region is of immense importance. Lumber industries have been established there, with the most improved appliances for cutting trees, transporting the logs to mills, and sawing them into lumber, much of which is loaded on ships and widely distributed. So vast is the forest, however, that as yet the natural conditions are but slightly changed, except in the immediate vicinity of tide-water, but the destruction from axe and fire has only been begun; the waste that, no doubt, is to continue is most disheartening.

Another centre in the vast and locally differentiated Pacific forest, as typical in its way as are the dense growths of fir and cedar just referred to, occurs on the Coast Range of north California, where the redwood (Sequoia sempervirens) is the all-important and characteristic tree. This redwood forest begins at the south in the vicinity of San Francisco, and extends northward, mainly on the moist seaward slopes of the Coast Ranges, to southwestern Oregon, but seldom reaches more than 30 miles inland.

The redwood resembles the cedar in habit, general appearance, character of its wood, and colour of bark and leaves. It flourishes best in moist localities, and attains a great size, surpassing in height and diameter of stem even the giant firs of Washington, and is only exceeded on this continent by its cousin, the great sequoia (Sequoia gigantea) of the western slope of the Sierra Nevada, in south-central California. It frequently attains a height of 300 or more feet, with a diameter at the base of 15 or 16, and in certain exceptional instances of over 20 feet. It rarely branches low, but almost invariably has a straight, fluted stem, perfectly symmetrical, rising with a slight taper for about 200 feet to the first limb. The foliage is dull green in colour, fine, and drooping. It is a most beautiful tree both in form and colour, and is markedly gregarious in habit. As stated by Henry Gannett, it forms the densest forest known if the comparison is made on the basis of the amount of merchantable lumber growing on a given unit of area. For example, the yellow-pine forests of the Southern Atlantic and Gulf States contain on an average about 5,000 feet, board measure (square feet of boards an inch thick), of timber per acre, and in the moderately dense portion of the white-pine forests of the Great Lakes region the average is about the same. In each of these regions, famed for their lumber, a tract containing 10,000 feet of lumber per acre would be considered as heavily forested. In the redwood forests of California, however, 50,000 feet of lumber per acre is not rare over extensive areas, while for special tracts containing many square miles this estimate may safely be doubled. Upon 96,443 acres in Humboldt County, California, the average amount of lumber contained in the trees still standing is 84,000 feet per acre. The returns of lumber companies during a continuous period of ten years from tracts which have been cleared show a return of 75,000 to 100,000 feet per acre, but even this is not the maximum. A certain tract of several square miles actually yielded 150,000 feet per acre; and there is on record a yield of 1,431,530 feet from a single acre. One tree is said to have furnished 66,500 feet of lumber, and another, 15 feet in diameter at the base, contained 100,000 feet. Another tree, still standing, measures 22 feet in diameter, and it is estimated will yield 200,000 square feet of boards an inch thick.

The wood of the redwood-tree is of a clear red colour with the exception of a thin layer just under the bark, which is almost pure white, and is light, soft, coarse-grained, and susceptible of a high polish. It is the most common and most valuable of all the forest products of the Pacific coast of North America, and is serviceable for a great variety of purposes.

The celebrated "big trees" of California are not to be confounded with the redwood described above, but belong to a different species of the same genus. The big trees are worthy of their name, as they are by far the largest in North America. When full-grown they average about 275 feet in height, with a diameter near the ground of about 20 feet. One of the tallest as yet measured has a height of 325 feet, and the largest a diameter of 35 feet 8 inches inside the bark and 4 feet above the ground. The age of one of these giants, as shown by the number of rings of growth in its trunk, is about thirteen hundred years; another, 24 feet in diameter, is twenty-two hundred years old; and a third showed over four thousand rings of growth, and must have been in its prime at the time of the birth of Christ. The trees occur in detached groves on the western slope of the Sierra Nevada in south-central California, but become more common southward, where they form a genuine forest belt. Their range from north to south is about 260 miles, and their elevation above the sea from 6,000 to 8,000 feet.

"So exquisitely harmonious," says John Muir, in his charming book The Mountains of California, "and finely balanced are even the very mightiest of these monarchs of the woods in all their proportions and circumstances, that there is never anything overgrown or monstrous about them. On coming in sight of them for the first time, you are likely to say, 'Oh, see what beautiful, noble-looking trees are towering there among the firs and pines!' their grandeur being in the meantime in great part invisible, but to the living eye it will be manifest sooner or later, stealing slowly on the senses like the grandeur of Niagara or the lofty Yosemite domes. Their great size is hidden from the inexperienced observer as long as they are seen at a distance in one harmonious view. When, however, you approach them and walk around them, you begin to wonder at their colossal size and seek a measuring-rod. These giants bulge considerably at the base, but not more than is required for beauty and safety; and the only reason that this bulging seems in some cases excessive is that only a comparatively small section of the shaft is seen at once in near views. One that I measured in the King's River forest was 25 feet in diameter at the ground and 10 feet in diameter 200 feet above the ground, showing that the taper of the trunk as a whole is charmingly fine. And when you stand back far enough to see the massive columns from the swelling instep to the lofty summit dissolving in a dome of verdure, you rejoice in the unrivalled display of combined grandeur and beauty. About 100 feet or more of the trunk is usually branchless, but its massive simplicity is relieved by the bark furrows, which, instead of making an irregular network, run evenly parallel, like the fluting of an architectural column, and to some extent by tufts of slender sprays that wave lightly in the winds and cast flecks of shade, seeming to have been pinned on here and there for the sake of beauty only. The young trees have slender simple branches down to the ground, put on with strict regularity, sharply aspiring at the top, horizontal about half-way down, and drooping in handsome curves at the base. By the time the sapling is five or six hundred years old this spiry, feathery, juvenile habit merges into a firm, rounded dome form of middle age, which in turn takes on the eccentric picturesqueness of old age. No other tree in the Sierra forest has foliage so densely massed or presents outlines so firmly drawn and so steadily subordinate to a special type.... The foliage of the saplings is dark bluish green in colour, while the older trees ripen to a warm brownish-yellow tint, like Libocedrus. The bark is rich crimson brown, purplish in young trees and in shady portions of the old, while the ground is covered with brown leaves and burrs forming colour masses of extraordinary richness, not to mention the flowers and underbrush that rejoice about them in their season. Walk in the sequoia woods at any time of year, and you will say they are the most beautiful and majestic on earth. Beautiful and impressive contrasts meet you everywhere; the colours of tree and flowers, rock and sky, light and shade, strength and frailty, endurance and evanescence, tangles of supple hazel-bushes, tree pillars about as rigid as granite domes, roses and violets the smallest of their kind, blooming around the feet of the giants. Then in winter the trees themselves break forth in bloom, myriads of small four-sided staminate cones crowd the ends of the slender sprays, colouring the whole tree, and when ripe dusting the air and ground with golden pollen."

Owing to the remoteness of the big trees from commercial centres, they have escaped to a great extent the destruction which everywhere attends the advent of the white man, and some of the finest groves are now under state protection.

The sequoias are not only of interest on account of their great size and grandeur, but from the fact that they are the lingering survivors of an ancient and once widely distributed genus. During the Cretaceous and Tertiary divisions of geological history the genus numbered at least 50 species, as has been shown by leaf impressions, fossil wood, and cones buried in the rocks of New Zealand and Chile on the south, Spitzbergen and Greenland on the north. Over North America they extend from the Atlantic to the Pacific. At present the only two species known, both of which, as already stated, are confined to the Pacific coast, and with the exception of a slight extension of the less gigantic of the two into southwestern Oregon, are found only in California.

While the firs, cedars, and redwoods form the major portion of the forests in the more humid regions on the western side of the continent, there are two species of pines growing in drier situations which in a general view are even more characteristic of the Pacific forest than are the sequoias. These two pines, well worthy to stand side by side with the giant firs and still more gigantic redwoods, are known as the sugar-pine and the yellow pine.

The sugar-pine grows amid the mountains from southwestern British Columbia, southward through western Washington, Oregon, and on the Sierra Nevada and Coast Ranges of California, at elevations ranging from 4,000 to 8,000 feet. It frequently clothes steep declivities or bids defiance to the storms on the crests of sharp ridges. In size it is scarcely exceeded by any of its companions excepting the firs and sequoias. It frequently attains a height of from 200 to 275 feet, with a diameter at the base of from 8 to 14, and in some instances of over 20 feet. Individual trees are known which have a height of 245 feet and are 18 feet in diameter. The branches are usually high above the ground and widely spreading. In the case of well-grown individuals they leave the main trunk with a sweeping, downward curve, which midway out changes to an upward curve, and at the extreme distal end droops once more. At the extremity of many of the far-reaching boughs there are suspended one or two cones, each 12 or 14 inches long and sometimes over 8 inches in diameter. The peculiar and frequently remarkably regular curvature of the great branches, giving them the form of half a Cupid's bow, imparts to these mighty pines a grace and symmetry possessed by few other trees. The familiar name of this great pine refers to the fact that from wounds or incisions in its trunk there exudes a sweet sap which is considered by many persons to exceed even the sap of the maple in agreeableness of flavour.

Lovers of beautiful trees will agree in considering the sugar-pine as the noblest of its family growing in the woods of America, if not the most majestic of its kindred in the world. Its only rival, but of a different type of beauty, is the Norfolk Island pine, of the south sea islands.

Of the many pleasant memories of camp life in the forests of America which are a source of delight to the writer none are recalled with greater pleasure than those associated with the sugar-pine of the Sierra Nevada, where the ground is carpeted with the long brown needles that fall in showers at certain seasons from the boughs far overhead. With the faded leaves are strewed also the great cones which always excite wonder and admiration. In the clear air and brilliant sunlight of the Californian mountains the luxuriant plume-like leaves far aloft appear to be formed of burnished silver or have the yellow of gold, according as the light strikes them, and at night the lofty boughs swayed by the winds make music such as no other forest can produce. Nothing in the vegetable world, not even the great sequoias, convey such an abiding impression of strength and majesty as these pines which have withstood the storms of centuries without losing their vigour or their symmetry and beauty of form. Unfortunately as it would seem, however, these magnificent trees are useful, as the term is commonly employed, and are fast falling a prey to lumbermen, who measure their value in dollars.

The yellow pine of the Pacific mountains, not to be confounded, however, with the yellow pine of the southern Appalachian region, fortunately has another common name, the silver pine, which is more appropriate and distinctive. This is the most widely spread, perhaps, of all the pines of North America, and is familiar to every one who has travelled through the Pacific mountains from British Columbia to Mexico, and from the Black Hills of Dakota or the mountains of Colorado and New Mexico westward to within hearing of the surf of the Pacific Ocean. It ranks second in size to the sugar-pine, but is a near rival in strength and nobleness of form. As might be inferred from its wide distribution, the silver pine had adapted itself to a great range of conditions, not only of climate, but of soil and height above the sea. It is found from an elevation of about 2,000 feet above the sea up the mountainsides nearly to timber-line, and flourishes alike in the hot, arid valleys and in regions bordering on perpetual snow and ice. One beautiful feature of the silver-pine forests is their open, park-like character. The trees stand far apart, and thus have room to reach not only a great size, but a remarkable degree of perfection of form. Between the islands of shade on the sunlit ground there is usually but little undergrowth, and the far-extending natural pastures permit one to ride in any direction without inconvenience.

One other pine of the widely extended Pacific forest demands attention even from the passing traveller, not on account of its size, for it is a dwarf in a land of giants, but for its wide distribution and the food its large, oily seeds furnish for birds, squirrels, and even for man. I refer to the piñon pine, of which there are several species. They are seldom over 35 or 40 feet high, and are not remarkable for beauty, although they furnish an agreeable feature in the sparsely forest-clothed and semiarid region where they thrive best, but they bear a profusion of small cones, each of which contains perhaps a dozen edible and nutritious seeds. These seeds were formerly used by the Indians for food on an extensive scale, and are still gathered in large quantities, and may be found in the markets of our cities. The Indian encampments in the piñon forests in the fall of the year are among the most picturesque features of these degenerate days of the aborigines.

In the southwest portions of the United States the forests are confined to the mountains and the higher table-lands, the hot, arid valleys being without trees other than the larger growths of cacti and yucca. Similar conditions are present in northern Mexico, but on the western side of that republic and throughout practically the whole of the peninsula of Lower California the mountains and valleys alike are treeless and desolate.

As stated by C. S. Sargent, the forests of North America, exclusive of Mexico, Central America, and the West Indies, contain arboreal representatives of 158 genera of plants, of which 94 genera occur in the Atlantic and 59 in the Pacific side of the continent, and 48 genera in the tropical portion of southern Florida. Of the number of genera of trees in the Caribbean forest we have no reliable census.

To the west of the Atlantic forest lie the broad natural meadows termed prairies, and still farther west the yet more extensive pasture-lands of the great plateaus which reach the eastern base of the Rocky Mountains (Fig. 28). The transition from the luxuriant and varied forest on the east to the treeless, thinly grass-covered plateaus on the west side of the interior Continental basin is gradual. The change occurs in the prairie region, where a struggle has been in progress for thousands of years between the conditions favouring and those adverse to tree growth. The balance of power, so to speak, is the amount of rain or of soil-stored moisture during the summer season. The gradual decrease in the mean annual precipitation from east to west on the inland border of the Atlantic forest continues westward, and on the plateaus adjacent to the Rocky Mountains the aridity is such that no trees can grow except along the immediate border of the stream, unless artificially irrigated.

The explanation of the absence of trees in the central and western portions of the interior Continental basin is found in the mean annual rainfall and the manner in which it is distributed throughout the year, together with variations in the texture and composition of the soil, and the disturbances in the natural conditions brought about by fires. The question, "Why are the prairies treeless?" has been variously answered by different observers. The outcome of a long discussion in this connection seems to be that the main cause of the absence of trees lies in the climatic conditions and principally in the lack of sufficient rain during the long, hot summers. Arid regions the world over are without forests, but the Prairie plains cannot be said to be arid; in fact, the mean annual rainfall over the greater portion of this region is equal to or exceeds that of many well-forested countries, averaging as it does in general about 30 inches. But the prairies lie between the more humid forest-covered regions on the east and the less humid or subarid plateaus on the west, and during the summer season droughts and hot, scorching winds are of common occurrence. It is the long dry summer that establishes the critical conditions, particularly about the eastern and northern borders of the prairies. Of secondary importance is the character of the soil. An exceedingly fine soil, like that of the prairies, as has been pointed out by J. D. Whitney, by excluding the air from the roots of trees is detrimental to their growth. Where the dryness of the summers make the lives of trees precarious the nature of the soil, whether coarse or fine, becomes the controlling factor. In the prairie region where the soil is more open and porous than usual, although other conditions remain the same, as in the Cross Timbers of Texas, trees flourish; while intervening areas where the soil is fine are typical prairies. Again, where the climatic conditions become critical, as during long, dry summers, the grass and other vegetation burns readily, fire spreads rapidly and widely, and young trees are destroyed. In the prairie region, as pointed out by J. W. Powell, the Indians were formerly in the habit of burning the grass each summer in order to insure more favorable pasturage for game during the succeeding spring. This annual burning kept back the forest and led to the eastward extension of the prairie.

During the past decade many groves have been planted on the prairies, and have flourished, especially when the adjacent fields are cultivated so as to allow the earth to store a larger share of the winter rain; the success of this tree planting, it has been claimed, is evidence that the nature of the soil is not a determining factor in the problem, because trees will grow if protected from fire. The success of arboriculture on the formerly treeless plains and plateaus, however, decreases as one travels westward. On the western border of the prairies and on the great plateaus, remote from streams, trees can be made to grow only by the aid of irrigation. If this region had never been swept by fire it is safe to say it would still be treeless. Each of the explanations referred to above to account for the treeless condition of the prairies—one referring it to soil conditions, and the other to the former prevalence of fires—certainly has much in its favour, and for certain localities seems satisfactory, but each point of view should include a broader range and recognise the fact that the requisite critical conditions have been furnished by wide-reaching climatic causes. The Prairie plains furnish but one phase of the gradual change that occurs in the natural mantle of vegetation when traced from the dense, well-watered forests of the Appalachians and the Alleghany plateau westward to the semiarid and truly arid lands of the great plateaus and Rocky Mountain region, where only such plants as are able to withstand long-continued drought can grow. This same broad conclusion is sustained also at the north, where the prairie dovetails, as it were, with the subarctic forest.

The general or underlying reason for the treeless condition of the vast central portion of the continent is doubtless a lack of sufficient rain. The precipitation that does occur comes mainly during the winter season, when the land is colder than the ocean; in summer the land becomes highly heated and imparts its temperature to the air, which thus has its capacity for moisture increased, and prolonged droughts occur. At the south, in Mexico and the adjacent portion of the United States, the trade-winds blow over a region which is more highly heated than the ocean from which they come, and are hence drying winds. To the west of the Great plateaus rise the Rocky Mountains, where climatic conditions are different on account of elevation, and, as we have seen, forests occur at considerable elevations, but not in the broader valleys. The conditions unfavourable for tree growth are continued and even intensified in the valleys of the central portion of the Pacific mountain region, and culminate in the deserts of the Great Basin and western Mexico. Throughout all of this vast treeless region the controlling condition is deficiency of moisture, particularly during the summer or growing season.

The nearest approach to desert conditions to be found in North America occur in the valley of Utah and Nevada and the southern portion of the Great Basin region in Arizona and Mexico. The bottoms of these valleys are, in some instances, occupied by shallow lakes in winter, when scanty rains occur, but during the long, hot summers they become completely desiccated, and are then broad expanses of hard mud, cracked by drying so as to resemble a tessellated pavement of cream-coloured marble. These mud-flats or playas are frequently absolutely without plant life. Excepting the playas, however, and, in numerous instances, a narrow belt of ground encircling them, which is white with efflorescent salts, the valleys of even the most arid portion of the Great Basin region are generally plant-covered. The most common and most widely spread of the shrubs on these shadeless plains is the sage-brush. So characteristic is this plant of countless valleys from Canada to Mexico within the general region of the Pacific mountains that to one familiar with the country the term "sage-brush land" brings to mind the leading features of the region designated. The sage-brush lands are far from being desert areas, however, for in early spring a profusion of low, sweet-scented flowers bloom beneath the gray-green Artemisia, and sufficient bunch-grass to sustain considerable herds may be expected in the same localities.

The vast, irregular belt of forest encircling the central treeless portion of the continent also dies out on its northern border, where the subarctic forest is succeeded northward by the Barren Grounds and tundra plains. Clearly the explanation of the absence of trees in the prairie region and the adjacent plateaus cannot be applied to scarcely less extensive treeless plains at the far north, where rain falls in summer and the soil is always abundantly charged with moisture. It needs no argument to show that the control among the conditions governing tree growth at the north passes to the temperate element of climate, and that the timber-line is there determined, as it is on high mountains, by the severity of the winters' storms and frosts and the shortness of the summers.

On the higher mountains of North America above the upper limit at which trees are able to grow there are picturesque regions carpeted and garlanded in late spring and summer with lovely flowers, the indescribable charms of which are only known to those who rejoice in climbing rugged peaks and in following the trails of the mountain-goat along sharp-crested ridges. The gorgeous blossoms of these roof-gardens of the world are much the same on all high mountains in temperate latitudes, but from having become first widely known to civilized man on the mountains of Switzerland, are generally termed alpine flowers. The most attractive features of an alpine flora, which springs into bloom as soon as the snow melts and forms a rapidly widening belt of colour as the margins of the snow-fields recede higher and higher, is the great profusion of brilliantly coloured blossoms. No sooner does the snow of winter melt than the moist ground becomes enamelled in brilliant colours on account of the springing up and quick blossoming of millions of hardy plants. The growing season on mountain heights is short, but the sun's energy is there more intense and the hours of light each day longer than in the valleys below, and the plants adapted to such conditions pass through their annual circle of changes from sprouting seed to mature fruit with remarkable rapidity. In many instances the mountain-climber finds beautiful lilies unfolding their sun-dyed blossoms at the bottom of well-like depressions in lingering snow-banks. The gleaming mountain-peaks when seen from afar are said to be crowned with snow, but the mountaineer rejoices in the knowledge that their cold diadems are wreathed and festooned about their lower margins with lovely blossoms. Many mountains less ambitious than their neighbours have the garlands without the crown. An alpine flora is present on the Pacific mountains from Mexico northward to Alaska. Like the "timber-line" and the "snow-line," the intermediate belt of profusely flowering herbaceous plants descends lower and lower with decrease in latitude; on the great volcanic cones of Mexico it has an elevation of over 15,000 feet; on the Sierra Nevada the greatest wealth of flowers occurs at about 12,000 feet; on Mount Rainier widely extended gardens resplendent with rainbow tints occur at 7,000 to 8,000 feet; and about the foot-hills near Mount St. Elias, at an elevation of 2,500 feet or less above the sea, every knoll and island-like area in the vast ice-fields is so densely overgrown with brilliantly flowered plants that one has to part the rank growths with his hands and press them aside with his alpenstick in order to force a way through the fields of bloom. Admirers of nature's loveliness who have not climbed to aspiring heights will find a new and beautiful world in the public alpine garden on the summit and about the snow-fields of the higher portions of the Pacific mountains, where no sign-boards forbid entry and no fences obstruct the way. In these regions nearest the sun and stars there are few, if any, plants of utility to man, but marvellous beauty and lavish profusion fill the foreground in every view. These glorious mountain heights have their use, however, although as yet known to but few; rest and recreation amid scenes at the same time novel and most inspiring may there be found by the toilers in our crowded cities.

Among the Atlantic mountains only a few summits attain a sufficient elevation to claim a wreath of alpine flowers. Something of the nature of the gorgeous fields of bloom about the great peaks of the Pacific mountains is suggested on the treeless summits of the White Mountains, but although classed by botanists among alpine floras, the plants growing there fail to give a true idea of the display characteristic of the mountains which make a nearer approach to the lower limit of perennial snow. In the southern Appalachians the absence of a luxuriant alpine flora is perhaps more than counterbalanced by the profusion of rhododendrons, azaleas, and laurels.