Timber-line in the high mountains of the West wakes up the most
indifferent visitor. The uppermost limit of tree-growth shows nature
in strange, picturesque forms, and is so graphic and impressive that
all classes of visitors pause to look in silent wonder. This is the
forest frontier.
It appears as old as the hills and as fixed and unchanging as they;
but, like every frontier, that of the forest is aggressive, is ever
struggling to advance. To-day this bold and definite line is the
forest's Far North, its farthest reach up the heights; but this simply
marks where the forest is, and not where it was or where it is
striving to be. Here is the line of battle between the woods and the
weather. The elements are insistent with "thus far and no farther,"
but the trees do not heed, and the relentless elements batter and defy
them in a never-ending battle along the timber-line.
From a commanding promontory the forest-edge appears like a great
shore-line, as it sweeps away for miles along the steep and uneven
sides of the mountains. For the most part it follows the contour line;
here it goes far out round a peninsula-like headland, there it sweeps
away to fold back into cove or cañon and form a forested bay. In
Colorado and California this forest-line on the mountains is at an
altitude of between eleven and twelve thousand feet. Downward from
this line a heavy robe of dark forest drapes the mountains; above it
the treeless heights rise cool and apparently barren, piled with old
and eroded snowdrifts amid silent moorlands and rocky terraces.
The trees of timber-line are stunted by cold, crushed by snow, and
distorted by prolonged and terrific winds. Many stretches appear like
growths of coarse bushes and uncouth vines. They maintain a perpetual
battle, and, though crippled, bent, dwarfed, and deformed, they are
stocky and strong old warriors, determined, no weaklings, no cowards.
They are crowded together and tangled, presenting a united front.
Few trees in this forest-front rise to a greater height than twelve
feet. The average height is about eight feet, but the length of some
of the prostrate ones is not far from the normal height. Wind and
other hard conditions give a few trees the uncouth shapes of
prehistoric animals. I measured a vine-like ichthyosaurus that was
crawling to leeward, flat upon the earth. It was sixty-seven feet
long, and close to the roots its body was thirty-eight inches in
diameter. One cone-shaped spruce had a base diameter of four feet and
came to a point a few inches less than four feet above the earth. Here
and there a tough, tall tree manages to stand erect. The high wind
either prevents growing or trims off all limbs that do not point to
leeward. Some appear as though molded and pressed into shape. A
profile of others, with long, streaming-bannered limbs, gives a
hopeful view, for they present an unconquerable and conscious
appearance, like tattered pennants or torn, triumphant battle-flags of
the victorious forest!
The forest is incessantly aggressive and eternally vigilant to hold
its territory and to advance. Winds are its most terrible and
effective foe. To them is due its weird and picturesque front.
Occasionally they rage for days without cessation, blowing constantly
from the same quarter and at times with the rending and crushing
velocity of more than one hundred miles an hour. These terrific winds
frequently flay the trees with cutting blasts of sand. At times the
wind rolls down the steeps with the crushing, flattening force of a
tidal wave. Many places have the appearance of having been gone over
by a terrible harrow or an enormous roller. In some localities all the
trees, except the few protected by rocky ledges or closely braced by
their encircling fellows, are crippled or overthrown.
[Illustration: THE WAY OF THE WIND AT TIMBER-LINE]
Although I have visited timber-line in a number of States, most of my
studies have been made on the eastern slope of the Continental Divide
in Colorado. This ragged edge, with its ups and downs and curves, I
have eagerly followed for hundreds of miles. Exploring this during
every month of the year, I have had great days and nights along the
timber-line. It was ever good to be with these trees in the clear air,
up close to the wide and silent sky. Adventurers they appeared,
strangely wrapped and enveloped in the shifting fog of low-drifting
clouds. In the twilight they were always groups and forms of friendly
figures, while by moonlight they were just a romantic camp of
fraternal explorers.
Many a camp-fire I have had in the alpine outskirts of the forest. I
remember especially one night, when I camped alone where pioneer
trees, rusty cliffs, a wild lake-shore, and a subdued, far-off
waterfall furnished sights and sounds as wild as though man had not
yet appeared on earth. This night, for a time, a cave man directed my
imagination, and it ran riot in primeval fields. After indulging these
prehistoric visions, I made a great camp-fire with a monumental pile
of tree-trunks and limbs on the shore of the lake, close to the cliff.
These slow-grown woods were full of pitch, and the fire was of such
blazing proportions that it would have caused consternation anywhere
in Europe. The leaping, eager flames threw wavering lights across the
lake on the steeply rising heights beyond. These brought the alarm cry
of a coyote, with many an answer and echo, and the mocking laughter of
a fox.
Even these wild voices in the primeval night were neither so strange
nor so eloquent as the storm-made and resolute tree-forms that rose,
peered, and vanished where my firelight fell and changed.
At most timber-lines the high winds always blow from one direction. On
the eastern slope of the Colorado divide they are westerly, down the
mountain. Many of the trees possess a long vertical fringe of limbs to
leeward, being limbless and barkless to stormward. Each might serve as
an impressive symbolic statue of a windstorm. Permanently their limbs
stream to leeward together, with fixed bends and distortions as though
changed to metal in the height of a storm.
Whenever a tree dies and remains standing, the sand-blasts speedily
erode and carve its unevenly resistant wood into a totem pole which
bears many strange embossed pictographs. In time these trees are
entirely worn away by the violence of wind-blown ice-pellets and the
gnawings of the sand-toothed gales.
Novel effects are here and there seen in long hedges of wind-trimmed
trees. These are aligned by the wind. They precisely parallel the
wind-current and have grown to leeward from the shelter of a boulder
or other wind-break. Apparently an adventurous tree makes a successful
stand behind the boulder; then its seeds or those of other trees
proceed to form a crowding line to the leeward in the shelter thus
afforded. Some of these hedges are a few hundred feet in length;
rarely are they more than a few feet high or wide. At the front the
sand-blasts trim this hedge to the height and width of the wind-break.
Though there may be in some a slight, gradual increase in height from
the front toward the rear, the wind trims off adventurous twigs on the
side-lines and keeps the width almost uniform throughout.
During the wildest of winds I sometimes deliberately spent a day or a
night in the most exposed places at timber-line, protected in an
elkskin sleeping-bag. Wildly, grandly, the surging gusts boomed,
ripped, roared, and exploded, as they struck or swept on. The
experience was somewhat like lying in a diver's dress on a beach
during a storm. At times I was struck almost breathless by an airy
breaker, or tumbled and kicked indifferently about by the unbelievable
violence of the wind. At other times I was dashed with sand and
vigorously pelted with sticks and gravel.
This was always at some distance from tree, boulder, or ledge, for I
took no risks of being tossed against trees or rocks. Many times,
however, I have lain securely anchored and shielded beneath matted
tree-growths, where in safety I heard the tempestuous booms and the
wildest of rocket-like swishes of the impassioned and invisible ocean
of air. The general sound-effect was a prolonged roar, with an
interplay of rippings and tumultuous cheerings. There were explosions
and silences. There were hours of Niagara. In the midst of these
distant roarings the fearful approach of an advancing gale could be
heard before the unseen breaker rolled down on me from the heights.
The most marked result of cold and snow is the extreme shortness of
the growing-season which they allow the trees. Many inclined trees are
broken off by snow, while others are prostrated. Though the trees are
flattened upon the earth with a heavy load for months, the snow cover
affords the trees much protection, from both the wracking violence of
the winds and their devitalizing dryness. I know of a few instances of
the winter snows piling so deeply that the covered trees were not
uncovered by the warmth of the following summer. The trees suspended
in this enforced hibernating sleep lost a summer's fun and failed to
envelop themselves in the telltale ring of annual growth.
Snow and wind combined produce acres of closely matted growth that
nowhere rises more than three feet above the earth. This growth is
kept well groomed by the gale-flung sand, which clips persistent twigs
and keeps it closely trimmed into an enormous bristle brush. In
places the surface of this will support a pedestrian, but commonly it
is too weak for this; and, as John Muir says, in getting through,
over, under, or across growths of this kind, one loses all of his
temper and most of his clothing!
Timber-line is largely determined by climatic limitations, by
temperature and moisture. In the Rocky Mountains the dry winds are
more deadly, and therefore more determining, than the high winds.
During droughty winters these dry winds absorb the vital juices of
hundreds of timber-line trees, whose withered standing skeletons
frequently testify to the widespread depredations of this dry blight.
A permanent advance, too, is made from time to time. Here and there is
a grove, a permanent settlement ahead of and above the main ranks. In
advance of these are a few lone trees, heroes scouting in the lead. In
moist, sheltered places are seedlings and promising young trees
growing up in front of the battle-scarred old guard. Advances on dry,
wind-swept ridges are more difficult and much less frequent; on a few
dry ridges these trees have met with a repulse and in some places
have lost a little territory, but along most of its front the
timber-line is slowly advancing into the heights.
With this environment it would be natural for these trees to evolve
more hardiness than the present trees have. This would mean trees
better fitted to contend with, and more likely to triumph over, the
harsh conditions. Evolutionary development is the triumphing factor at
the timber-line.
The highest timber-line in the world is probably on Mount Orizaba,
Mexico. Frank M. Chapman says that there are short-leaved pines
(_Pinus Montezumæ_) from thirty to forty feet high, on the southern
exposure of this peak at an altitude of about 13,800 feet. In
Switzerland, along the steep and snowy Alps, it is sixty-four hundred;
on Mt. Washington, about forty-five hundred feet. In the mountains of
Colorado and California it is of approximately equal altitude, between
eleven and twelve thousand feet. Advancing northward from California
along the timber-line, one enters regions of heavy snow-fall as well
as of restricting latitude. Combined, these speedily lower the
altitude of timber-line, until on Mt. Rainier it is below eight
thousand feet. There is a noticeable dwarfing of the forest as one
approaches the Land of the Midnight Sun, and in its more northerly
reaches it comes down to sea-level to form the Land of Little Sticks.
It frays out at its Farthest North just within the Arctic Circle. Most
of the Arctic Ocean's icy waves break on treeless shores.
Everywhere at timber-line the temperature is low, and on Long's Peak
the daily average is two degrees below the freezing-point. At
timber-line snow may fall any day of the year, and wintry conditions
annually prevail from nine to ten months. The hardy trees which
maintain this line have adjusted themselves to the extremely short
growing-season, and now and then mature and scatter fertile seeds. The
trees that do heroic service on all latitudinal and altitudinal
timber-lines of the earth are members of the pine, spruce, fir, birch,
willow, and aspen families. At timber-line on the Rocky Mountains
there are three members each from the deciduous trees and the
evergreens. These are the Engelmann spruce, limber pine, alpine fir,
arctic willow, black birch, and quaking aspen.
A few timber-line trees live a thousand years, but half this time is a
ripe old age for most timber-line veterans. The age of these trees
cannot be judged by their size, nor by general appearance. There may
be centuries of difference in the ages of two arm-in-arm trees of
similar size. I examined two trees that were growing within a few
yards of each other in the shelter of a crag. One was fourteen feet
high and sixteen inches in diameter, and had three hundred and
thirty-seven annual rings. The other was seven feet high and five
inches in diameter, and had lived four hundred and ninety-two years!
One autumn a grizzly I was following--to learn his bill-of-fare--tore
up a number of dwarfed trees at timber-line while digging out a
woodchuck and some chipmunks. A number of the smaller trees I carried
home for careful examination. One of these was a black birch with a
trunk nine-tenths of an inch in diameter, a height of fifteen inches,
and a limb-spread of twenty-two. It had thirty-four annual rings.
Another was truly a veteran pine, though his trunk was but six-tenths
of an inch in diameter, his height twenty-three inches, and his
limb-spread thirty-one. His age was sixty-seven years. A midget that I
carried home in my vest pocket was two inches high, had a limb-spread
of about four inches, and was twenty-eight years of age.
A limber pine I examined was full of annual rings and experiences. A
number of its rings were less than one hundredth of an inch in
thickness. At the height of four feet its trunk took on an acute angle
and extended nine feet to leeward, then rose vertically for three
feet. Its top and limbs merged into a tangled mass about one foot
thick, which spread out eight feet horizontally. It was four hundred
and nine years old. It grew rapidly during its first thirty-eight
years; then followed eighteen years during which it almost ceased
growing; after this it grew evenly though slowly.
One day by the sunny and sheltered side of a boulder I found a tiny
seed-bearer at an altitude of eleven thousand eight hundred feet. How
splendidly unconscious it was of its size and its utterly wild
surroundings! This brave pine bore a dainty cone, yet a drinking-glass
would have completely housed both the tree and its fruit.
Many kinds of life are found at timber-line. One April I put on
snowshoes and went up to watch the trees emerge from their months-old
covering of snow. While standing upon a matted, snow-covered thicket,
I saw a swelling of the snow produced by something moving beneath.
"Plainly this is not a tree pulling itself free!" I thought, and stood
still in astonishment. A moment later a bear burst up through the snow
within a few yards of me and paused, blinking in the glare of light.
No plan for immediate action occurred to me; so I froze. Presently the
bear scented me and turned back for a look. After winking a few times
as though half blinded, he galloped off easily across the compacted
snow. The black bear and the grizzly occasionally hibernate beneath
these low, matted tree-growths.
The mountain lion may prowl here during any month. Deer frequent the
region in summer. Mountain sheep often take refuge beneath the
clustered growths during the autumn storms. Of course the audacious
pine squirrel comes to claim the very forest-edge and from a point of
safety to scold all trespassers; and here, too, lives the cheery
chipmunk.
This is the nursery, or summer residence, of many kinds of birds. The
"camp-bird," the Rocky Mountain jay, is a resident. Here in spring the
white-crowned sparrow sings and sings. During early summer the
solitaire, the most eloquent songster I have ever heard, comes up from
his nest just down the slope to pay a tribute of divine melody to the
listening, time-worn trees. In autumn the Clarke crow appears and,
with wild and half-weird calls of merriment, devours the fat nuts in
the cones of the limber pine. During this nutting, magpies are present
with less business than at any other time and apparently without a
plan for deviltry. Possibly they are attracted and entertained by the
boisterousness of the crows.
[Illustration: A TIMBER-LINE LAKE IN NORTHWESTERN COLORADO]
Lovely wild-flower gardens occupy many of the openings in this torn
and bristling edge of the forest. In places acres are crowded so
closely with thrifty, brilliant bloom that one hesitates to walk
through and trample the flowers. Here the columbine, the paintbrush,
the monument-plant, and scores of other bright blossoms cheer the wild
frontier.
Rarely are strangers in the mountains thoroughly aroused. They need
time or explanation in order to comprehend or appreciate the larger
scenes, though they do, of course, have periodic outbursts in
adjectives. But at timber-line the monumental scene at once has the
attention, and no explanation is needed. Timber-line tells its own
stirring story of frontier experience by a forest of powerful and
eloquent tree statues and bold, battered, and far-extending figures in
relief.
Only a few of the many young people whom I have guided to timber-line
have failed to feel the significance of the scene, but upon one party
fresh from college the eloquent pioneer spirit of the place made no
impression, and they talked glibly and cynically of these faithful
trees with such expressions as "A Doré garden!" "Ill-shapen fiends!"
"How foolish to live here!" and "Criminal classes!" More appreciative
was the little eight-year-old girl whose ascent of Long's Peak I have
told of in "Wild Life on the Rockies." She paid the trees at
timber-line as simple and as worthy a tribute as I have ever heard
them receive: "What brave little trees to stay up here where they have
to stand all the time with their feet in the snow!"
The powerful impressions received at timber-line lead many visitors to
return for a better acquaintance, and from each visit the visitor goes
away more deeply impressed: for timber-line is not only novel and
strange, it is touched with pathos and poetry and has a life-story
that is heroic. Its scenes are among the most primeval, interesting,
and thought-compelling to be found upon the globe.