from the 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, the great trunks of the sequoia last for centuries after they fall. I have a specimen block of sequoia wood, cut from a fallen tree, which is hardly distinguishable from a similar section cut from a living tree, although the one cut from the fallen trunk has certainly lain on the damp forest floor 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 four feet in diameter and 380 years old was growing, as I determined by cutting it half through and counting the rings, thus demonstrating that the remnant of the trunk that made the ditch has 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 before the seed from which the monumental fir sprang fell into the prepared soil and took root. Now, because sequoia trunks are never wholly consumed in one forest fire, and those fires recur only at considerable intervals, and because sequoia ditches after being cleared are often left unplanted 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 late one.
Again, admitting that upon those areas supposed to have been once covered with sequoia forests, every tree may have fallen, and every trunk may have been 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 beyond 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 time. Nevertheless, the questions may be asked: Is the species verging toward 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 as to the question of former extension. In the northern groups, as we have seen, there are few young trees or saplings growing up around the 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 the climate is supposed to be exceptionally favorable. But the story told by the majestic continuous forests of the south creates a very different impression. No tree in the forest is more enduringly established in concordance with both climate and soil. It grows heartily everywhere--on moraines, rocky ledges, along watercourses, and in the deep, moist alluvium of meadows with, as we have seen, a multitude of seedlings and saplings crowding up around the aged, abundantly able to maintain the forest in prime vigor. 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 landslip not exceeding two acres in area. This soil-bed was about seven years old, and had been seeded almost simultaneously by pines, firs, libocedrus, and sequoia, presenting a 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. Toward the south where the sequoia becomes most exuberant and numerous, the rival trees become less so; and where they mix with sequoias they grow up beneath them like slender grasses among stalks of Indian corn. Upon a bed of sandy floodsoil 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 instance of conditions which have enabled sequoias to crowd out 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 the sequoia, also furnishes the bare ground required for its growth from the seed. Fresh ground is, however, furnished in sufficient quantities for the renewal of the forests without the aid of fire--by the fall of old trees. The soil is thus upturned and mellowed, and many trees are planted for every one that falls.
It is constantly asserted in a vague way that the Sierra was vastly wetter than now, and that the increasing drought will of itself extinguish the sequoia, leaving its ground to other trees supposed capable of flourishing in a drier climate. But that the 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 always found only in well-watered places?" 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 mistake to suppose that the water is the cause of the grove being there; on the contrary, the grove is the cause of the water being there. Drain off the water and the trees will remain, but cut off the trees, and the streams will vanish. Never was cause more completely mistaken for effect than in the case of these related phenomena of sequoia woods and perennial streams.
When attention is called to the method of sequoia stream-making, it will be apprehended at once. The roots of this immense tree fill the ground, forming a thick sponge that absorbs and holds back the rain and melting snow, only allowing it to ooze and flow gently. Indeed, every fallen leaf and rootlet, as well as long clasping root, and prostrate trunk, may be regarded as a dam 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.
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 rain and snowfall since the close of the glacial period in the Sierra is much less than is commonly guessed. The highest post-glacial water-marks are well preserved in all the upper river channels, and they are not greatly higher than the spring flood-marks of the present; showing conclusively that no extraordinary decrease has taken place in the volume of the upper tributaries 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 sufficient for the luxuriant growth of sequoia forests. Indeed, all my observations tend to show that in a prolonged drought the sugar pines and firs would perish before the sequoia, not alone because of the greater longevity of individual trees, but because the species can endure more drought, and make the most of whatever moisture falls.
Again, if the restriction and irregular distribution of the 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 not been governed by superior conditions of soil as to fertility or moisture, by what has it been governed?
In the course of my studies I observed that the northern groves,
