On the Post-Glacial History of Sequoia Gigantea.
ON THE POST-GLACIAL HISTORY OF Sequoia Gigantea. By JOHN MUIR, OF MARTINEZ, CAL, From the Proceedings of the American Association for the Advancement of Science, Buffalo Meeting, August, 1876. ON THE POST-GLACIAL HISTORY OF SEQUOIA GIGANTEA By John Muir, of Martinez, Cai,. During the past summer I e...
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1877
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| Summary: | ON THE POST-GLACIAL HISTORY OF Sequoia Gigantea. By JOHN MUIR, OF MARTINEZ, CAL, From the Proceedings of the American Association for the Advancement of Science, Buffalo Meeting, August, 1876. ON THE POST-GLACIAL HISTORY OF SEQUOIA GIGANTEA By John Muir, of Martinez, Cai,. During the past summer I explored tbe Sequoia belt of the Sierra Nevada, tracing its boundaries and learning what I could of tbe post-glacial history of the species, and of its future prospects. Perhaps the most important of the questions put to tbe forests are as follows :— What area does Sequoia now occupy as the principal tree? Was the species eve? more extensively distribjded on the Sierra during post-glacial times? Is the species verging to extinction? And if so, then to what causes will its extinction be due? What have been Us relation to climate, to soil, and to other coniferous trees with which it is associated? What are those relations now? What are they likely to be in the future? Some of tbe answers obtained to these questions, seem plain and full of significance, and cannot I think, fail to interest every student of natural history. I shall endeavor, therefore, to present them in as clear and compact a shape as possible. By reference to the map exhibited it will be seen that tbe Sequoia belt extends from the well known Calaveras groves on the north, to the bead of Deer Creek on tbe south, a distance of about 200 miles. Tbe northern limit being a little above tbe 38th parallel, tbe southern a little below tbe 36th, and the elevation above sea-level varies from about 5000, to 8000 feet. * From tbe Calaveras to tbe south fork of King's River, the species occurs only in small isolated groves 'and patches, so sparsely distributed along the belt.tbat two gaps occur nearly forty miles in width, one between tbe Calaveras and Tuolumne groves, tbe. other between those of tbe Fresno and King's River. Hence southward the Sequoia is not gathered in small sequested groups, but stretches across tbe broad and rugged basins of tbe Kaweab and Tule in noble forests, a distance of nearly seventy miles, and with a Widtbof from°jthree to ten *Since this paper was written a sniall grove of some six or eight trees has been discovered ou the Middle fork of the American River in Placer county, about 65 miles to the north of the Calaveras grove. —4 — miles, tbe continuity of the belt being broken here only by deep sheer-walled canons. The Fresno group, the largest to the northward, occupies an area of three or four square miles. From tbe so-called King's River Grove in tbe neighborhood of Thomas' Mill, I pushed off in a northeasterly direction, along the bevelled rim of tbe canon of the south fork of King's River. Here I discovered a majestic forest of Sequoia, nearly .six miles long, b}' two wide; not hemmed in closely by pines and firs, but growing as tbe predominant species, in brave and comfortable independence, over bill and dale and rocky ridge-top. Tbis is the northmost assemblage of Sequoias that may fairly be called a forest. Descending the precipitous divide between King's River and tbe Kaweab, we enter tbe colossal forests of tbe main continuous portion of tbe belt. As we advance southward, tbe trees become more and more irrepressibly exuberant, tossing tbeir massive crowns against the sky from eve ridge-top, and waving onward in graceful compliance to the complicated topography of the basins of tbe Kaweab and Tule. Tbe finest of tbe Kaweab portion of tbe belt is located on tbe broad, lofty ridge separating the waters ot Marble Creek from tbe Middle fork, and extends from the granite headlands overlooking tbe hot plains, back wdthin a few miles of the cool glacial fountains. The extreme upper limit of the belt is reached between tbe Middle and South forks at an elevation of 8,400 feet above the sea. The most compact and majestic portion of tbe Tule forests, lies on tbe North fork, forming, I think, the finest block of Sequoia in the entire belt. Southward from here I thought I could detect a slight decrease in tbe general thrift of the forests this being the only indication of approach to tbe southern limit. But shortly after crossing the divide between tbe basins of the Tule and Deer Creek, tbe belt is abruptly contracted and terminated. I made a careful survey of the southern boundary, and of tbe woods beyond, without discovering a single Sequoia. I was greatly interested, boWever, to find that tbe species bad crossed over from tbe head of Deer Creek into tbe Valley of tbe Upper Kern, and planted colonies northward along the eastern slopes of tbe Greenhorn Range, a spur which puts out from tbe main axis of tbe range at tbe bead of King's River, trending southward, and enclosing the Upper Kern valley on tbe west, and it is just where this lofty spur begins to break down, on its approach to its southern termination, that the Sequoia bas been able to cross it. Though tbe area occupied by tbe species increases from north to south, there is no corresponding increase in tbe size of tbe trees; a diameter of twenty feet, and height of 275, is, perhaps, about tbe average for full-grown trees; specimens twenty-five feet in diameter are not rare, and a good many approach 300 feet in beigbt. Occasionally one meets a specimen thirty feet in diameter, and rarefy one that is larger. The largest I have yet seen and measured is a majestic stump on tbe south side of King's River. It measures thirty-five feet eight inches in diameter inside tbe bark four feet from tbe ground, and a plank thus wide of solid wood could be obtained from it without a decaying fibre. Tbe main continuous portion of tbe belt, stretching across tbe basins of the Kaweab and Tule, forms tbe greater portion of the entire coniferous forest, and is plainly visible from the San Joaquin Valley, tbe light fringe of pines in front not being dense enough to bide it, while it extends so far up tbe range, there is but little space left for pines or firs above it. Was the species ever more extensively distributed on the Sierra in post-glacial times? I have been led to the conclusion that it never was.- Because careful search along tbe margins of tbe groves, and in tbe gaps between, fails to discover a single trace of its previous existence beyond its present bounds. Notwithstanding I feel confident, that if every Sequoia in the range were to die to-day, numerous monuments of their existence would remain, of so imperishable a nature as to be available for the student more than ten thousand years bence. In the first place we might notice that no species of conif- — 6 — erous tree in tbe range keeps its individuals so well together as Sequoia; a mile is perhaps tbe greatest distance of any straggler from tbe main body, and all of those stragglers that have come under my observation are young, instead of old monumental trees, relics of a more extended growth. Again, we might notice in this connection, tbe well-known longevity of the Sequoia. A tree was felled last summer in the old King's River Grove, whose annual rings, counted by three different persons, numbered from 2125, to 2137; and this specimen was b3r no means a very aged looking tree, and measured only twenty-three feet in diameter inside the bark, while the giant of the New King's River forest mentioned above, is nearly twice as large, and probably about twice as old; for it is standing on dry gravelly ground where the growth has been slow, the annual rings measuring only about the one-thirtieth of an inch throughout a considerable portion of the diameter. Again,.Sequoia trunks frequently endure for centuries after they fall. I have a specimen block, cut from a fallen trunk, which is hardly distinguishable from specimens cut from living trees, although the old trunk fragment from which it was derived has lain exposed in the damp forest more than 380 years, probably thrice as long. The time measure, in the case, is simply this. When the ponderous trunk, to which the old vestige belonged, fell it sunk itself into the ground, thus making a long straight ditch, and in the middle of this ditch, a silver fir is growing, that is now four feet in diameter, and 380 years old, as determined by cutting it half through and counting the rings, thus demonstrating that the remnant of the trunk that made the ditch, bas lain on the ground more than 380 years. For it is evident that to find the whole time, we must add to the 380 years, the time that the vanished portion of the trunk lay in the ditch before being burned out of the way, plus the time that passed ere the seed from which the monumental fir sprang fell into the prepared soil and took root. Now, because Sequoia trunks are never wholty consumed in one forest fire, and those fires recur only at considerable intervals, and because Sequoia ditches after being — 7 — cleared are often left implanted for centuries, it becomes evident that the trunk remnant in question may probably have lain a thousand years or more. And this instance is by no means a rare one. But admitting that upon those areas supposed to have been once covered'with Sequoia every.tree may have fallen, and every trunk burned or buried, leaving not a remnant, many of the ditches made by the fall of the ponderous trunks, and the bowls made by their upturning roots, would remain patent for thousands of years after the last vestige of the trunks that made them had vanished. Much of this ditch-writing would no doubt be quickly effaced by the flood-action of overflowing streams, and rain-washing; but no inconsiderable portion would remain enduringly engraved on ridge-tops bejond such destructive action; for, where all the conditions are favorable, it is almost imperishable. Now these historic ditches, and root bowls occur in all the present Sequoia groves and forests, but as far as I have observed, not the faintest vestige of one presents itself outside of them. We therefore conclude that the area covered by Sequoia has not been diminished during the last eight or ten thousand years, and probably not at all in post-glacial times. Is the species verging to extinction? What are its relations to climate, soil, and associated trees? All the phenomena bearing on these questions, also throw light, as we shall endeavor to show, upon the peculiar distribution of the species, and sustain the conclusion already arrived at on the question of extension. In the northern groups there are few young trees or saplings growing up around the failing old ones to perpetuate the race, and inasmuch as those aged Sequoias, so nearly childless, are the only ones commonly known, the species to most observers seems doomed to speedy extinction, as being nothing more than an expiring remnant, vanquished in the so-called struggle for life by pines and firs that have driven it into its last strongholds, in moist glens where climate is exceptionally favorable. But the language of the majestic continuous forests of the South, creates a very different impression. No tree of all the forest is more enduringly established in concordance with climate and soil. It grows heartily everywhere, on moraines, rocky ledges, along water-courses, and in the deep moist alluvium of meadows, with a multitude of seedlings and saplings crowding up around the aged, seemingly abundantly able to maintain the forest in prime vigor. For every old storm-stricken tree, there is one or more in all the glory of prime and for each of these, many young trees, and crowds of exuberant saplings. So that if all the trees of any section of the main Sequoia forest were ranged together according to age, a very promising curve would be presented, all the way up from last year's seedlings to giants, and with the young and middle-aged portion of the curve, many times longer than the old portion. Even as far north as the Fresno, I counted 536 saplings and seedlings growing promisingly upon a piece of rough avalanche soil not exceeding two acres in area. This soil bed is about seven years old, and has been seeded almost simultaneously by pines, firs, libocedrus, and Sequoia, presenting a remarkably simple and instructive illustration of the struggle for life among the rival species and it was interesting to note that the conditions thus far affecting them have enabled the young Sequoias to gain a marked advantage. In every instance like the above, I have observed that the seedling Sequoia is capable of growing on both drier and wetter soil than its rivals, but requires more sunshine than the}'; the latter fact being clearly shown wherever a sugar pine or fir is growing in close contact with a Sequoia of about equal age and size, and equally exposed to the sun; the branches of the latter in such cases are always less leafy. Towards the south, however, where the Sequoia becomes more exuberant and numerous, the rival trees become less so and where \\vty mix with Sequoias, they mostty grow up beneath them, like slender grasses among stalks of Indian corn. Upon a bed of sandj' flood-soil I counted ninety-four Sequoias, from one to twelve feet high, on a patch of ground once occupied by four large sugar pines which lay .crumbling beneath them an in- — 9 — stance of conditions which have enabled Sequoia to crowd but the pines. I also noted eighty-six vigorous saplings upon a piece of fresh ground prepared for their reception by fire. Thus fire, the great destroyer of Sequoia, also furnishes bare virgin ground, one of the conditions essential for its growth from the seed. Fresh ground is however furnished in sufficient quantities for the constant renewal of the forests without fire, viz., by the fall of old trees. The soil is thus upturned and mellowed, and many trees are planted for every one that falls. Landslips and floods also give rise to bare virgin ground and a tree now and then owes its existence to a burrowing wolf or squirrel, but the main supply of fresh soil is furnished by the fall of aged trees. The climatic changes in progress in the Sierra, bearing on the tenure of tree life, are entirely misapprehended, especially as to the time, and the means, employed by nature in effecting them. It is constantly asserted in a vague way, that the Sierra was vastly wetter than now, and that the increasing drouth will of itself extinguish Sequoia, leaving its ground to other trees supposed capable of flourishing in a drier climate. But that Sequoia can and does grow on as dry ground as any of its present rivals, is manifest in a thousand places. "Why then" it will be asked, "are Sequoias alwa3'S found in greatest abundance in well watered places where streams are exceptionally abundant? " Simply because a growth of Sequoias creates those 'streams. The thirsty mountaineer knows well that in every Sequoia grove he will find running water, but it is a very complete mistake to suppose that the water is the cause of the grove being there for on the contrary, the grove is the entire cause of the water being there drain off the water and the trees will remain, but cut off the trees, and the 1 j streams will vanish. Never was cause more completely mis taken for effect than in the case of these related phenomena of Sequoia woods and perennial streams, and I confess that at first I shared in the blunder. When attention is called to the method of Sequoia stream- making, it will be apprehended at once. The roots of this — ig — immense tree fill the ground, forming a thick sponge, that absorbs, and holds back the rains and melting snows, only allowing them to ooze and flow gently. Indeed every fallen leaf, and rootlet, as well as long clasping root, and prostrate trunk, may be regarded as dams, hoarding the bounty of storm- clouds, and dispensing it as blessings all through the summer, instead of allowing it to go headlong in short-lived floods. Evaporation is also checked by the dense foliage to a greater extent than by any other Sierra tree and the air is entangled in masses and broad sheets, that are quickly saturated while thirsty winds are not allowed to go sponging and licking along the ground. So great is the retention of water in many places in the main belt that bogs and meadows are created by the killing of the trees. A. single trunk falling across a stream in the woods forms a dam 200 feet long, and from ten to thirty feet high, giving rise to a pond, which kills the trees within its reach. These dead trees fall in turn, thus making a clearing, while sediments gradually accumulate changing the pond into a bog, or meadow, for a growth of carices and sphagnum. In some instances a chain of small bogs or meadows rise above one another on a hillside, which are gradually merged into one another, forming sloping bogs or meadows which form striking features of Sequoia woods, and since all the trees that have fallen into them have been preserved, they contain records of the generations that have passed since they began to form. Since, then, it is a fact that thousands of Sequoias are growing thriftily on what is termed dry ground, and even clinging like mountain pines to rifts in granite precipices and since it has also been shown that the extra moisture found in connection with the denser growths is an effect of their presence, instead of a cause of their presence then the notions as to the former extension of the species, and its near approach to extinction, based upon its supposed dependence on greater moisture are seen to be erroneous. The decrease in the rain and snowfall since the close of the glacial epoch in the Sierra is much less than is commonly guessed. Tbe highest post-glacial water-marks are well preserved in all the upper river channels, and they are not greatly higher than the spring floodmarks of the present; showing conclusively that no extraordinary decrease has taken place in the volume of post-glacial Sierra streams since they came into existence. But in the meantime eliminating all this complicated question of climatic change, the plain fact remains, that the present rain and snowfall is abundantly stijficient for the luxuriant groivth of Sequoia forests. Indeed all my observations tend to show that in case of prolonged drouth the sugar pines and firs would die before Sequoia, not alone because of tbe greater longevity of individual trees, but because the species can endure more actual drouth, and make the most of whatever moisture falls. Only a few of the very densest fir and pine woods felt and weave a root-sponge sufficiently thick and extensive for the maintenance of perennial springs, while every Sequoia grove does. Again, if tbe restriction and irregular distribution of tbe species be interpreted as a result of the desiccation of the range, then instead of increasing as it does in individuals toward the south'where the rainfall is less, it should diminish. If then the peculiar distribution of Sequoia has notbeen. governed by superior conditions of soil as to fertility or moisture, by what has it been governed ? .Several years ago I observed that the northern groves, the only ones I was then acquainted with, were located on just those portions of tbe general forest soil-belt that were first laid bare towards the close of the glacial period when the ice- sheet began to break up into individual glaciers. And last summer while searching the wide basin of tbe San Joaquin, and trying to account for the absence of Sequoia where every condition seemed favorable for its growth, it occurred to me that this remarkable gap in tbe Sequoia belt is located exactly in the basin of tbe vast ancient mer de glace of tbe San Joaquin and King's River basins, which poured its frozen' floods to the plain, fed by tbe snows that fell on more than fifty miles of the summit. I then perceived that tbe other great gap in the belt, forty miles wide, extending between the H Calaveras and Tuolumne groves, occurs in the basin of the great ancient mer de glace of the Tuolumne and Stanislaus basins, and that the smaller gap between the Merced and Mariposa groves, occurs in the basin of tbe smaller glacier of the Merced. The wider the ancient glacier, the wider the corres- ponding gap in the Sequoia belt. Finally, pursuing my investigations across the basins of the Kaweah and Tule, I discovered that the Sequoia belt attained its greatest development, just where, owing to the topographical peculiarities of the region, the ground had been most perfectly protected from the main ice-rivers, that continued to pour past from the summit fountains, long after the smaller local glaciers had been melted. Taking now a general view of the belt, beginning at the south we see that the majestic, ancient glaciers were shed off right and left down the valleys of Kern and King's Rivers by the lofty protective spurs outspread embracingty above the warm Sequoia-filled basins of the Kaweab and Tule. Then next northward occurs the wide Sequoia-less channel or basin of tbe ancient San Joaquin and King's River mer de glace. Then the warm, protected spots of Fresno and Mariposa groves. Then the Sequoia-less channel of the ancient Merced glacier. Next the warm, sheltered ground of the Merced and Tuolumne groves. Then the Sequoia-less channel of the grand ancient met de glace of the Tuolumne arid Stanislaus; and lastly tbe warm, old ground of the Calaveras groves. What the other conditions may have been that enabled Sequoia to establish itself upon these oldest and warmest portions of the main glacial soil-belt, I cannot say. I might venture to state, however, in this connection, that since tbe Sequoia forests present a more and more ancient aspect as they extend -feaefeward, I am inclined to think that the species was distributed from the south. While the sugar pine, its great rival in the northern groves, seems to have come around the bead of the Sacramento valley and down the Sierra from the north. Consequently when the Sierra soil-beds were first thrown open to preemption on the melting of the ice-sheet, Sequoia may have established itself along the available portions — 13 — of the south half of the range, prior to tbe arrival of tbe sugar pine while the sugar pine took possession of the north half, prior to tbe arrival of Sequoia. But, however much uncertainty may attach to this branch of tbe question, there are no obscuring shadows upon tbe grand general relationship we have pointed out between the present distribution of Sequoia and the ancient glaciers of the Sierra. And when we bear in mind that all tbe present forests of tbe Sierra are young, growing on moraine soil recently deposited, and that the flank of tbe range itself, with all its landscapes is new-born, recently sculptured and brought to tbe light of day from beneath the ice mantle of the glacial winter, then a thousand lawless mysteries disappear, and broad harmonies take their places. But although all the observed phenomena bearing on tbe post-glacial history of this colossal tree point to tbe conclusion that it never was more widely distributed on tbe Sierra since the close of the glacial epoch; that its present forests are scarcely past prime, if indeed they have reached prime; that the post-glacial day of the species is probably not half done yet, when from a wider outlook tbe vast antiquity of the genus is considered, and its ancient richness in species and individuals comparing our Sierra Giant and Sequoia sempervirens of the coast, the only other living species, with the twelve fossil species already discovered, and described by Heer and Lesquereux, some of which seem to have flourished over vast areas around tbe polar zone, and in Europe, and our own territories, during tertiary and cretaceous times,—then indeed it becomes plain that our two surviving species, restricted to narrow belts within the limits of California, are mere remnants of the genus, both as to species, and individuals, and that they probably are verging to extinction. But tbe verge, of a period beginning in cretaceous times, may have a breadth of tens of thousands of years, not to mention tbe possible existence of conditions calculated to multiply and reextend both species and individuals. This, however, is a branch of the question beyond the present discussion. In studying tbe fate of our forest king, we have thus far — .14— considered tbe action of purely natural causes only but unfortunately man is in the woods, and waste and pure destruction are already making rapid headway. If the importance of forests were at all understood, even from an economic standpoint, their preservation would call forth the most watchful attention of government. In ' the meantime however, scarce anything definite is known regarding them, and tbe simplest ground-work for available legislation is not yet laid, while every species of destruction is moving on with accelerated speed. In the course of last year's explorations I found no less than five mills located on, or near, tbe lower edge of the Sequoia belt, all of which saw more or less of tbe "big tree" into lumber. One of these, located on the north fork of tbe Kaweah, cut over 2,000,000 feet of big tree lumber last season. Most of the Fresno group are doomed to feed tbe mills recently erected near them, and a company has been formed to cut the magnificent forest on King's River. In tbese milling operations waste far exceeds use for after tbe choice young manageable trees on any given spot have been felled, tbe woods are fired to clear the ground of limbs and refuse with reference to further operations, and of course most of the seedlings and saplings are destroyed. These mill ravages however, are small as compared with tbe comprehensive destruction caused by "Sheepmen." Incredible numbers of sheep are driven to tbe mountain pastures every summer, and their course is ever marked by desolation. Every wild botanic garden is trodden down, the shrubs are stripped of leaves as if devoured by locusts, and the woods are burned. Running fires are set everywhere, with a view to clearing the ground of prostrate trunks, to facilitate tbe movements of the flocks, and improve the pastures. Tbe entire forest belt is thus swept and devastated from one extremity of the range to the other, and with the exception of tbe resinous Pi?ius contorta, Sequoia suffers most of all. Indians burn off tbe underbrush in certain localities to facilitate deer-hunting, mountaineers carelessly allow their camp-fires to run, so do lumbermen, but tbe fires of the sheepmen or Muttoneers, form — 15 — more than ninety percent, of all destructive fires that range the Sierra forests. Some years ago a law was enacted by tbe California legislature with special reference to tbe preservation of Sequoia gigantea, under which the cutting down of trees over sixteen feet in diameter became illegal, but on the whole, a more absurd and short-sighted piece of legislation could not be conceived for all the young trees on which tbe permanence of the forest depend, may be either burned or cut with impunity, while tbe old trees may also be burned provided only they are not cut! It appears, therefore, that notwithstanding our forest king might live on gloriously in Nature's keeping, it is rapidly vanishing before the fire and steel of man and unless protective measures be speedily invented and applied, in a few decades at the farthest, all that will be left of Seqtwia gigantea will be a few hacked and scarred monuments. https://scholarlycommons.pacific.edu/jmb/1002/thumbnail.jpg |
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