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By Willis Linn Jepson
Professor of Botany, University of California
The Big Tree or Sequoia gigantea is one of the most charmingly attractive features of Yosemite National Park. This most wonderful and most lovable of all tree species occurs in scattered communities or "groves" on the western slopes of the Sierra Nevada Mountains between the elevations of 4600 and 8000 feet.
Of the twenty-six groves, the northernmost, near Lake Tahoe, contains but six trees. Further southward the species becomes more and more abundant until, in the region near the Kings and Kern Rivers, great forests are formed. The largest and most famous of these is the Giant Forest of Sequoia National Park.
Within Yosemite National Park are three groves. The Tuolumne Grove, about 1 1/2 miles west of Crane Flat on the Big Oak Flat Road, contains 40 trees Which occur at about 5800 feet elevation. The Merced Grove, about 3 miles east of Hazel Green, contains 33 trees and is traversed by the Coulterville Road to Yosemite at an altitude of 5500 feet. The Mariposa Grove 4 miles southeast of Wawona on the mountain heights above the South Fork of the Merced River contains 490 mature trees.
This latter grove is in a number of respects the most remarkable of all clusters of the Big Trees which occur in the society called the "grove." It really consists of two almost distinct groups of trees, the upper grove of 364 trees at an altitude of 7000 feet, and the lower grove of 126 trees at an elevation of 5400 feet. The road first enters the lower grove, passing between the Four Sentinel trees, with the fifth, the Sergeant of the Guard, standing a little apart. Soon a cluster of large Sequoias comes into view. Among these, prostrate, lies the Father of the Forest along whose trunk a six-horse stage has been driven and at one time a whole troop of cavalry lined up in formation.
The road winds upward and tunnels directly beneath the base of the Wawona Tree through a passage sufficiently large for the largest of old-time stage coaches and modern auto-busses. Beyond this point is the Alabama Tree which is considered the most perfect and symmetrical tree in the grove. After passing many individuals which ennoble the forest by their commanding size, the roads of the grove finally center at the Big Tree Cabin which is set amid a cluster of truly magnificent specimens of this wonderful race of forest giants. All of these trees have been individualized with favorite names, such as Ohio, Massachusetts, General Lafayette, St. Louis, Philadelphia, Galen Clark, and many more. The Old Guard consists of four very fine trees in a row. The four trees of the Diamond Group are so disposed that they form the corners of a diamond. About ninety-eight trees of the upper grove and thirteen of those in the lower grove have received names.
The dimensions in feet of a number of the more remarkable trees of the Mariposa Grove as given by
Big Tree Cabin in the Mariposa Grove. The cabin was built around 1860 by Galen Clark
Photo by A. C. Pillsbury
|Tree||Height||Diam. at 10 ft.||Diam. at Base|
|Capt. A. E. Wood||310||12.7||16.5|
The height of the Big Tree commonly averages from 125 to 225 feet, but trees in excess of these figures are well known. The best authenticated of recent figures of the extreme heights of known trees are those for the General Sherman Tree in Sequoia National Park which is 279.9 feet high and for the Dalton Tree in the Muir Grove which is 292 feet high. These appear to be extreme figures for trees in the forests of the southern Sierra Nevada. The Columbia Tree in the Mariposa Grove is 294 feet high and the Mark Twain Tree is said to be 331 feet high, a figure in excess of any measurements hitherto given which have been made by presumably accurate methods.
Height is a matter which can be determined with fair degree of accuracy and when determined is not variable. Diameter, on the other hand, is not so definitely determinable. Diameters at the ground do not, in many cases, give significant or proportionate values to the trunks for the reason that the Big Trees Often swell excessively at the base. The writer has found by actual measurement that the diameter at the base in certain cases is twice that at ten feet above the ground. The only figures valid for purposes of comparison must therefore be taken sufficiently above the ground to minimize the error due to this factor. As so many people have a natural interest in the largest known diameters there are here given the diameters of the four most famous trees:
|Name of Tree||Diameter|
at 12 ft.
|27 1/2 ft.||34 1/3 ft.|
(General Grant Park)
|23 "||35 1/4 "|
|20 (at 11 ft.)||31 1/4 "|
|Boole Tree (Converse|
Basin, King’s River)
|25 3/4 (at 10 ft.)||36 "|
It must here be emphasized, however, that characteristically the taper is very slight. Indeed, all observers unite in agreeing that the outstanding feature of the Big Tree, more remarkable and impressive than any other, is the columnar character of its trunk. The great height of the clear column and the manner in which it maintains its diameter upward from the ground to the crown are most extraordinary.
In the matter of longevity the Big Tree is undoubtedly edly the oldest living thing on the planet. Its age varies from 900 to 2100 years and in not a few cases it probably attains to an age of 3000 years. The age of one tree logged in the Converse Basin has been determined with closely approximate accuracy as 3148 years. This is the oldest tree of which we have any definite record.
Standing in rhapsodical admiration before a Sequoia gigantea one can easily imagine it to be 5000 or 10,000 years of age. The figure eight thousand years has been placed on the Grizzly Giant at the instance of a distinguished authority on fishes. As a matter of fact no one knows the age of the Grizzly Giant as there is no satisfactory way of determining its age except by cutting it down. A small core could be taken from its trunk by a special tool, but this means might not prove satisfactory, and such mutilation is not likely to be permitted. There is no way of determining the age of a particular individual merely by means of the diameter. From various age studies I have found, on the average, about 20 years to the inch. The Father of the Forest in the Calaveras Grove has a diameter of 27 feet inside the bark at about 8 feet above the ground. Its calculated age would therefore be 6480 years. When cut down its age was determined to be about 1300 years. In the Converse basin the writer determined the age of a tree 11 feet 7 1/2 inches in diameter to be 2019 years. The ring count was accurate within a possible error of only 10 or 15 years in either direction. Another tree 24 feet in diameter, twice the diameter of the first, was only 1346 years old—a little over half the age of the first. Trees of various species often take on an appearance of great age when comparatively young, due to storm, wind, disease, or under-nutrition. Senility or its appearance is not always a matter of years, and attempts to assign a longevity of four thousand years or more to the Big Tree rest on no substantial basis.
The age of individual Big Trees, however imposing their life, should not be confused with the age of the Sequoia race. The Big Tree is descended from pine-like ancestors, and the Pine Family itself and its allies are very much older racially than the Redwood Family to which the Big Tree belongs. The morphology of the flowers and cones of a pine, not to speak of the presence of resin, indicate a family very much older than the Redwood Family. Measured in terms of history of life upon this earth, the species of Sequoia are recent; they are relatively modem compared with the pines, firs, and spruces, and their allies—indeed, they are the merest parvenues.
In another sense they have a highly dignified ancestry and represent a race of trees which were once more numerous upon the surface of the earth than at present. During the Miocene age of the Tertiary period many species of Sequoia were distributed over the northern hemisphere and perhaps also occurred in the southern hemisphere. At any rate the remains of Sequoia species have been observed in the rocks of Austria, France, England, western Asia, Spitzbergen, at the mouth of the Mackenzie River, British Columbia, Yellowstone Park, Oregon, and many other stations. They undoubtedly formed very extensive forests during the Miocene period. It is supposed that during one of the glacial ages all the species became extinct excepting the two which are now living in California, viz., the Big Tree of the Sierras (Sequoia gigantea) and the Redwood of the Californian Coast Ranges (Sequoia sempervirens).
Of these two species the Big Tree grows to a much more colossal size. It begins as a young tree with the pyramidal outline of an arbor-vitae, its trunk clothed with branches to the ground and its crown tapering to a cone-like apex. After it attains to the age of two or three hundred years it becomes a tree 75 to 125 feet high, and begins to prune its trunk of branches from the ground upwards. As it goes into the adult period, the crown continues to move upward and a clear shaft results which is 100 to 150 feet or more up to the first limb and clothed with a deeply furrowed fibrous red bark which is very non-inflammable.
The Sierran forest is typically a fire forest; that is to say, all the tree species have shown reaction in structure or life history to long continued fires which have undoubtedly run over California woodlands for many thousands of years and perhaps for a longer period. The trunks of the pines, firs, and cedars have become encased in exceedingly thickened bark which is undoubtedly a very effective protection to the vital cambium layer which lays between the bark and the wood and provides for the tree’s increase in thickness. The bark of these trees, on the other hand, contains more or less resin which increases the fire hazard.
In the case of the Big Tree, however, there is practically no resin in the whole trunk. Resin is found not at all in the tree except in microscopic quantities in the first annual layer of wood, in the leaves, and in the staminate catkins. The bark is quite free from resin except for its possible occurrence in case of mutilation, and by its peculiar fibrous nature forms an almost asbestos-like covering to the trunk. This bark is a beautiful red-brown or cinnamon color six to twelve inches thick. It often attains a greater thickness, and bark two feet through is actually known. Fires burn through this heavy layer of bark very slowly, and it is only after repeated conflagrations that the Forest Fiend obtains entrance to the woody layers. Even then progress is slow because the wood is non-resinous and burns slowly. Nearly all mature trees or trees past maturity show signs of fire ravage, although in many cases the attack has been negligible.
As the tree grows on past maturity it eventually begins to die in the top. This may be the result of the gradual exhaustion of its food supply or it may be due to years of deficient seasonal rainfall. It is possible that the tops of Sequoias may be killed by lightning, but we know of no direct evidence to this effect. We certainly have no record of a Sequoia tree ever having been killed by lightning, although pines, firs, and other trees of the Sierran forests are frequently killed or completely shattered. Probably all old trees of Sequoia gigantea have been struck by lightning; certainly very many of them within the period of the white man’s observation.
One of the most remarkable of forest experiences is to see at night a fire burning 150 or 200 feet in the air in the very tip-top of a great Sequoia tree. Such fires are set by lightning. On account of their inaccessibility and their tendency to throw off live sparks, they are a great source of worry to the forest ranger who can do nothing but camp in the neighborhood until the fire burns itself out or is extinguished by a propitious rainfall.
The cone of the Big Tree is two to three inches long and bears two hundred to three hundred seeds, about twenty-five per cent. of which are viable. It is quite common to hear tourists marvel at the ridiculously small size of the cone borne by so gigantic a tree, but the complacent tourist may well be thankful that the size of the cone does not correspond to the size of the tree beneath which he stands with admiring gaze.
In some of the rhapsodies which have been spoken
Typical forest in the Mariposa Grove. Left to right, Sugar
Pine, Red Fir, Incense Cedar, Sequoia, young Sugar
Pine, group of Firs, and Sequoia. The ground
is covered with Sugar Pine Cones
Photo by A. C. Pillsbury
The appearance of the wood does not differ very much from that of the well-known Coast Redwood. It is much the same color, texture, and weight. The difference in strength can well be illustrated by observation that in Tulare County vineyards, grapevine stakes made from Big Tree wood are two inches square, while in Napa Valley vineyards, similar stakes made from Redwood are about one inch square. Redwood resists a far greater lateral strain than the Big Tree wood. The latter has a tendency to fracture transversely When split, whereas the Redwood splits cleanly throughout. One sometimes sees in the beds of Sierran rivers huge but short logs which are broken off squarely at the ends. These great leviathans have been weathered by successive floods and are often smoothed by rolling from side to side of the canyon wall. They are fractured segments of the trunks of the great giants of the Sierra. In the Big Tree, the Sugar Pine, the Yellow Pine. the Red and White Firs, and the Incense Cedar we have in this Yosemite region the finest and most remarkable group of conifers in the world. They serve to give the park an interest and charm which highly gratifies our aesthetic sense and stirs deeply our imagination regarding this earth upon which we live. The Big Tree and the Yellow Pine would be fit tenants for Paradise, and this region is Paradise enow.
Chase, J. S., 1911. Yosemite Trails.. (Houghton, Mifflin Co., Boston) pp. 1-354, 16 illus., 1 map.
Dudley, W. R., and others. 1900. A Short Account of the Trees of California. U. S. Dept. of Agric., Div. Forestry Bull. 28, 30 pp., 17 pls.
Hutchings, J. M., 1888. In the Heart of the Sierras. (Pacific Press, Oakland) 496 pp., about 200 woodcuts, photo-plate and maps. The Big Trees on pp. 216-232 & 241-247. Ill.
Jepson, W. L., 1909. Trees of California.
(Potter Bros., S. F.),
288 pp., 117 figs., illus., pls., The Big Trees on pp. 101-106.
1910. Silva of California. (Univ. Press, Berkeley) 480 pp., 85 pls., illus., The Big Tree on pp. 58, 139-147.
Kellogg, A., 1882. Forest Trees of California. Second Report of the State Mineralogist of California, App. 1, pp. 1-148. The Big Tree on pp. 21-24.
Muir, John, 1894. The Mountains of California. (The Century Co., N. Y.) 382 pp., illus., The Big Tree on pp. 179-200.
Shinn, Chas. H., 1889. "The Big Tree." Garden and Forest, 2: 614-615.
Sudworth, G. B., 1908. Forest Trees of the Pacific Slope. Dept. Agric. Div. Forestry, Bull., pp. 441, maps. illus., The Big Tree on pp. 139- 145.
Williamson, R. S., 1857. The Mammoth Trees of California. Pacific Railroad Report, 5: 257-259.
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