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.

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 series 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 make 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 snow-fall since the close of the glacial period in the Sierra is much less than is commonly guessed.