Читать книгу American Forest Trees - Henry H. Gibson - Страница 11

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This interesting and peculiar pine has a number of names, most of which are descriptive. The whiteness of the bark and the stunted and recumbent position which the tree assumes on bleak mountains are referred to in the names whitestem pine in California and Montana, scrub pine in Montana, whitebark in Oregon, white in California, and elsewhere it is creeping pine, whitebark pine, and alpine whitebark pine. It is a mountain tree. There are few heights within its range which it cannot reach. Its tough, prostrate branches, in its loftiest situations, may whip snow banks nine or ten months of the year, and for the two or three months of summer every starry night deposits its sprinkle of frost upon the flowers or cones of this persistent tree. It stands the storms of centuries, and lives on, though the whole period of its existence is a battle for life under adverse circumstances. At lower altitudes it fares better but does not live longer than on the most sterile peak. Its range covers 500,000 square miles, but only in scattered groups. It touches the high places only, creeping down to altitudes of 5,000 or 6,000 feet in the northern Rocky Mountains. It grows from British Columbia to southern California, and is found in Montana, Idaho, Washington, Oregon, Nevada, Arizona, and California. Its associates are the mountain climbers of the tree kingdom, Engelmann spruce, Lyall larch, limber pine, alpine fir, foxtail pine, Rocky Mountain juniper, knobcone pine, and western juniper. Its dark green needles, stout and rigid, are from one and one-half to two and one-half inches long. They hang on the twigs from five to eight years. In July the scarlet flowers appear, forming a beautiful contrast with the white bark and the green needles. In August the seeds are ripe. The cones are from one and one-half to three inches long. The seeds are nearly half an inch long, sweet to the taste. The few squirrels and birds which inhabit the inhospitable region where the whitebark pine grows, get busy the moment the cones open, and few escape. Nature seems to have played a prank on this pine by giving wings to the seeds and rendering their use impossible. The wing is stuck fast with resin to the cone scales, and the seed can escape only by tearing its wing off. The heavy nut then falls plumb to the ground beneath the branches of its parent. It might be supposed that a tree situated as the whitebark pine is would be provided with ample means of seedflight in order to afford wide distribution, and give opportunity to survive the hardships which are imposed by surroundings; but such is not the case. The willow and the cottonwood which grow in fertile valleys have the means of scattering their seeds miles away; but this bleak mountain tree must drop its seeds on the rocks beneath. In this instance, nature seems more interested in depositing the pine nuts where the hungry squirrels can get them, than in furnishing a planting place for the nuts themselves—therefore, tears off their wings before they leave the cone. The battle for existence begins before the seeds germinate, and the struggle never ceases. The tree, in parts of its range, survives a temperature sixty degrees below zero. Its seedlings frequently perish, not from cold and drought, but because the wind thrashes them against the rocks which wear them to pieces. Trees which survive on the great heights are apt to assume strange and fantastic forms, with less resemblance to trees than to great, green spiders sprawling over the rocks. Trees 500 years old may not be five feet high. Deep snows hold them flat to the rocks so much of the time that the limbs cannot lift themselves during the few summer days, but grow like vines. The growth is so exceedingly slow that the new wood on the tips of twigs at the end of summer is a mere point of yellow. John Muir, with a magnifying glass, counted seventy-five annual rings in a twig one-eighth of an inch in diameter. Trunks three and one-half inches in diameter may be 225 years old; one of six inches had 426 rings; while a seventeen-inch trunk was 800 years old, and less than six feet high. Such a tree has a spread of branches thirty or forty feet across. They lie flat on the ground. Wild sheep, deer, bear, and other wild animals know how to shelter themselves beneath the prostrate branches by creeping under; and travelers, overtaken by storms, sometimes do the same; or in good weather the sheepherder or the hunter may spread his blankets on the mass of limbs, boughs, and needles, and spend a comfortable night on a springy couch—actually sleeping in a tree top within two feet of the ground. In regions lower down, the whitebark pine reaches respectable tree form. Fence posts are sometimes cut from it in the Mono basin, east of the Sierra Nevada mountains. In the Nez Perce National Forest trees forty feet high have merchantable lengths of twenty-four feet. Similar growth is found in other regions. In its best growth, the wood of whitebark pine resembles that of white pine. It is light, of about the same strength as white pine, but more brittle. The annual rings are very narrow; the small resin passages are numerous. The sapwood is very thin and is nearly white. Men can never greatly assist or hinder this tree. It will continue to occupy heights and elevated valleys.

Bristlecone Pine (Pinus aristata) owes its name to the sharp bristles on the tips of the cone scales. It is known also as foxtail pine and hickory pine. The latter name is given, not because of toughness, but on account of the whiteness of the sapwood. It is strictly a high mountain tree, running up to the timber line at 12,000 feet, and seldom occurring below 6,000 or 7,000 feet. It maintains its existence under adverse circumstances, its home being on dry, stony ridges, cold and stormy in winter, and subject to excessive drought during the brief growing season. Trees of large trunks and fine forms are impossible under such conditions. The bristlecone pine’s bole is short, tapers rapidly and is excessively knotty. The species reaches its best development in Colorado. Though it is seldom sawed for lumber, it is of much importance in many localities where better material is scarce. In central Nevada many valuable mines were developed and worked by using the wood for props and fuel. Charcoal made of it was particularly important in that region, and it was carried long distances to supply blacksmith shops in mining camps. Railways have made some use of it for ties. Though rough, it is liked for fence posts. The resin in the wood assists in resisting decay, and posts last many years in the dry regions where the tree grows. Ranchmen among the high mountains build corrals, pens, sheds, and fences of it; but the fibers of the wood are so twisted and involved that splitting is nearly impossible, and round timbers only are employed. The bristlecone pine can never be more important in the country’s lumber supply than it is now. It occupies waste land where no other tree grows, and it crowds out nothing better than itself. It clings to stony peaks and wind-swept ridges where the ungainly trunks are welcome to the traveler, miner, or sheepherder who is in need of a shed to shelter him, or a fire for his night camp. In situations exposed to great cold and drying winds, the bristlecone pine is a shrub, with little suggestion of a tree, further than its green foliage and small cones. The needles are in clusters of five. They cling to the twigs for ten or fifteen years. The seeds are scattered about the first of October, and the wind carries them hundreds of feet. They take root in soil so sterile that no humus is visible. Young trees and the small twigs of old ones present a peculiar appearance. The bark is chalky white, but when the trees are old the bark becomes red or brown.

Foxtail Pine (Pinus balfouriana) owes its name to the clustering of its needles round the ends of the branches, bristling like a fox’s tail. The needles are seldom more than one and one-half inches in length, and are in clusters of fives. They cling to the branches ten or fifteen years before falling. The cones are about three inches long, and are armed with slender spines. The tree is strictly a mountain species and grows at a higher altitude than any other tree in the United States, although whitebark pine is not much behind it. It reaches its best development near Mt. Whitney, California, where it is said to grow at an altitude of 15,000 feet above sea level. It has been officially reported at Farewell Gap, in the Sierra Nevada mountains, at an altitude of 13,000. At high altitudes it is scrubby and distorted, but in more favorable situations it may be sixty feet high and two in diameter. On high mountains it is generally not more than thirty feet high and ten inches in diameter. It is of remarkably slow growth, and comparatively small trees may be 200 or 300 years old. The wood is moderately light, is soft, weak, brittle. Resin passages are few and very small. The wood is satiny and susceptible of a good polish, and would be valuable if abundant. The seeds are winged and the wind scatters them widely, but most of them are lost on barren rocks or drifts of eternal snow. The untoward circumstances under which the tree must live prevent generous reproduction. It holds its own but can gain no new foothold on the bleak and barren heights which form its environment. The dark green of its foliage makes the belts of foxtail pines conspicuous where they grow above the timber line of nearly all other trees. Its range is confined to a few of the highest mountains of California, particularly about (but not on) Mt. Shasta and among the clusters of peaks about the sources of Kings and Kern rivers. Those who travel and camp among the highest mountains of California are often indebted to foxtail pine for their fuel. Near the upper limit of its range it frequently dies at the top, and stands stripped of bark for many years. The dead wood, which frequently is not higher above the ground than a man’s head, is broken away by campers for fuel, and it is often the only resource.