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Bui, 24, Div. of Forestry, U S. Dept of Agr

Frontispiece.

Bulletin No. 24.

U. S. DEPARTMENT OP AGRIOULTUEE.

DIVISION OF FORESTRY.

A PRIMER OF FORESTRY.

Part I.-THE FOREST.

FORESTER.

WASHINGTON:

GOVEKNAIENT PRINTING OFFICE
1899.

LETTER OF TRANSMITTAL.

U. s. Department of Agriculture,

Division of Forestry,
Washington, D. C, May 8, 1699,

Sir: I have tlie honor to transmit herewith the man-
uscript of the first half of "A Primer of Forestry," and
to recommend its publication as Bulletin No. 24, Part
I, of this Division. The present part ("The Forest")
deals with the units which compose the forest, with its
character as an organic whole, and with its enemies.
It may be said to sketch the foundation of the practice
of forestry and of forest policy. Part IT will be enti-
tled " Practical Forestry," and will deal with the prac-
tice of forestry, with work in the woods, with the
relations of the forest to the weather and the streams,
and will conclude with a brief description of forestry at
home and abroad.

For many of the illustrations of Part I, I am in-
debted to the kindness of several gentlemen not con-
nected with this Division. Their names and the plates
and figures which I owe to their courtesy are as follows :

The Director of the U. S. Geological Survey, figs. G5,
06, and 74; Mr. George W. Vanderbilt, of Biltmore,
N. C., figs. 8, 54, 58, the frontispiece, and PI. XXIII 5
Forstmeister U. Meister, of Zurich, Switzerland, fig. 41
and PI. XL; the inspector- general of forests to the
government of India, Pis. TV and XII; Mr. A. li.

3

4 A PIUMER OF FORESTRY.

Moore, of Millville, Oal., Pis. Y, XIII, and XLII; Mr.
U. F. Bender, of New York City, fig. 79; Mr. A. P.
Low, of the geological survey of Canada, PI. XT 5 Mr.
A. G. Wallihan, of Lay, Colo., PI. XIY.

Three plates are from sources difficult to trace. The
remainder of the plates and figures (except figs. 14 and
59, which are diagrams) are from photographs in my
collection, which were taken, in about equal proportions,
by Mr. Henry S. Graves, now Assistant Chief of this
Division, and myself.

Kespectfully, Gifford Pinchot,

Forester ,
Hon. James Wilson,

Secretary of Agriculture,

CONTENTS.

Page.

Chapter I. — The Life of a Tree 7

The parts of a tree 8

The food of a tree 11

The composition of wood 14

How the tree breathes 15

Transpiration 16

The growth of a tree 18

The structure of wood 19

Annual rings 22

Heartwood and sap wood 23

Chapter II. — Trees in the Forest 25

The various requirements of trees 25

Requirements of trees for heat and moisture 26

Requirements of trees for light 30

Tolerance and intolerance 32

The rate of growth 36

The reproductive power of trees 37

The succession of forest trees 39

Pure and mixed forest 39

Reproduction hy sprouts 42

Chapter III. — The Life of a Forest 44

A community of trees 44

The life of a forest crop 46

The seven ages of a tree 47

How the crop begins 49

The forest cover established 51

The beginning of the struggle 52

Growth in height 54

The struggle continued 56

Natural pruning 58

5

6 CONTENTS.

Chapter III. — The Life of a Forest — Contiuued. Page.

The culmination of growtli _ 60

The end of the struggle 61

Death from weakness and decay 64

Destructive lumbering 65

Conservative lumbering 66

Chapter IV. — Ekemies of the Forest 67

Man and nature in the forest 67

Grazing in the forest. 69

Grazing and fire 70

Trampling 71

Browsing 72

Forest insects 73

Forest fungi 74

Wind in the forest 75

Snow in the forest 76

Forest fires 77

Historic forest fires 79

Means of defense 83

Surface fires 84

Ground fires 85

Back-firing 86

Fire lines 88

ILLUSTRATIONS.

Number.

Plates 47

Text figures 83

A PRIMER OF FORESTRY.

CHAPTER I.

THE LIFE OF A TREE.

The object of forestry is to discover and apply the
principles according to which forests archest managed.
It is distinct from arboriculture, which deals with indi-
vidual trees. Forestry has to do with single trees only
as they stand together on some large area whose prin-
cipal crop is trees, and which therefore forms part of a
forest. (See frontispiece.) The forest is the most highly
organized portion of the vegetable Avorld. It takes its
importance less from the individual trees which help to
form it than from the qualities which belong to it as a
whole. Although it is composed of trees, the forest is
far more than a collection of trees standing in one
place. It has a population of animals and i)lants pecul-
iar to itself, a soil largely of its own making, and a
climate different in many ways from that of the open
country. Its influence upon the streams alone makes
farming possible in many regions, and everywhere it
tends to i)revent floods and drought. It supplies fuel,
one of the first necessaries of life, and lumber, the raw
material, without which cities, railroads, and all the
great achievements of material progress would have

7

8

A PRIMER OF FORESTRY.

been either long delayed or wliolly impossible. (See
PI. I.) The forest is as beautiful as it is useful. The old

fairy tales which spoke of it
as a terrible place are wrong.
No one can really know the
forest without feeling the gen-
tle influence of one of the
kindliest and strongest parts
of n ature. Prom every point
of view it is one of the most
helpful friends of man. Per-
haps no other natural agent
has done so much for the
human race and has been so
recklessly used and so little
understood.

THE PARTS OF A TREE.

In order rightly to under-
stand the forest, something-
must first be known about
the units of which it is made
up. A tree, then, is a woody
I)lant growing up from the
ground usually with a single
stem. (See fig. 1.) It con-
sists of three parts: First,
the roots, which extend into
the ground to a depth of 3 or
4 feet, or still farther when
the soil is not too hard and
they do not find moisture enough near the surface. (See
figs. 2, 3, and Pis. II, III.) They hold the tree in place.

Fia. 1. — Roots, stem, and crown of
ayoungShellbarkHickory. Mil-
ford, Pa.

Bui. 24, Div. of Forestry, U. S. Dept of Agr

THE PARTS OF A TREE.

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Fig. 2.— Roots of the Western Hemlock. This youug tree started on a fallen
lied Fir; its roots spread under the moss and litter, and when flrc came they
were exposed. Olympic Forest Reserve, "Washington.

Fig. 3.— Upturned skeleton roots of a Red Fir. The small roots hare been
Lurned away and the others cleared of soil by the fire. Olympic Peninsula,
AVashington.

10

A PRIMER OF FORESTRY.

aud take up from the soil water and certain mineral sub-
stances which the tree needs
in its growth. Second, the
trunkj stem, or bole, which
supi)orts the crown and sup-
plies it with mineral food
and water from the roots.
(See fig. 4.) Third, the
crown itself, with its net-
work of branches,buds, and
leaves, in which all tliefood
taken up by the tree from
the soil and air is worked
over and made ready to
assist in the growth of
the whole plant. (See figs.
5-7 and PL IV.) The
crown has more to do with
the life of the tree than its
other parts, for the most
important processes in the
reproduction of the tree and
the digestion of its food
take place in the crown.
For this reason, and be-
cause we can control its
shape and size more easily
and directly than that of
the roots or trunk, the
crown is of special inter-

I^4.-TrunksoftwoKedFirs. The ^^^ ^^ ^^^ forCStcr. It iS
figure of a man between them gives an almOSt CXClusi VCly with the

idea of tiieir great size, which, how- crowus that he has to deal

ever, is not unusual. Olympic Forest .

Eeserve, Washington. HI tending a Crop of trceS

Bui 24, Div. of Forestry, U. S. Dept. of Agr.

Plate II.

THE FOOD OF A TREE.

11

and preparing tbe way for the succeeding genera-
tion. As they stand together in the forest, the crowns
of the trees form a broken shelter,
which is usually spoken of as the
leaf canopy, but which may better
be called the cover. (See fig. 8.)

THE FOOD OF A TREE.

The materials upon which a tree
feeds are derived from the soil and
the air. The minute root hairs which
spring from the rootlets take up
water from the ground, and with it
various substances which it holds in
solution. These are the earthy con-
stituents of the tree, which reappear
in the form of ashes when any part of
it is burned. The water which con-
tains these materials goes straight
from the roots to the leaves, in which
a most important process in the feed-
ing of the tree takes place. This proc-
ess is the assimilation or taking up
and breaking up, by the leaves, of
carbonic acid gas from the air. Jt
goes on only in the presence ot light
and heat, and through the action of
chlorophyll, a substance from which
the leaves and the young bark get
their green color.

Plants containing chlorophyll are
the chief means by which mineral
materials are changed into food, so that nearly all
plant and animal life depends upon them. Plant cells

Fig. 5.— Crown and stem
of a young Western
Larch. Priest River
Forest Reserve,
Idaho.

12

A PRIMER OF FORESTRY.

which contain chlorophyll break ni) the carbonic acid
gas with which they come in contact, retain the carbon,
one of its elements, and send back the other, oxygen,

into the air. Then, still
under the influence of the
sunlight, they combine the
carbon with the oxygen
and hydrogen of the water

Fig. 6.— Crowns of the Black Hemlock
(to the left) and Western Cedar.
Washington Fore.st Reserve.

from the roots into new
chemical compounds, in
which nitrogen and the
earthy constituents men-
tioned above are also pres-
ent; that is to say, the food
materials which reach the
tree through the roots and
leaves are first digested in the leaves somewhat as food
is digested in the human body, and are then sent
to all living parts of tlie roots, stem, and crown, where
they pass through another process of digestion, and are

Fig. 7. — Stem and crown of a Long-
leaf Pine, tlie latter covered witli
moss swaying in the wind.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate III.

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3-

o" I

THE FOOD OF A TREE.

13

Fig. 9.— Yearly growth of a branch of Horse Chestnut. The bands of wrinkles
mark the divisions between tlie jfrowths of four successive years. The dis-
tance between these bauds would never have been greater than it was when
the branch was cut.

14

A PRIMER OF FORESTRY.

then either used at once in growth or stored away until
the proper moment arrives. This is the general rule,
but it is believed that in some cases food taken up by

the roots can be used
without first being
digested in the leaves.

THE COMPOSITION
OF WOOD.

Wood is made up
chiefly of carbon, oxy-
gen, and hydrogen.

Fig.

10. — Bark of the Western Hemlock.
Washington Forest Reserve.

When i)erfectly dry, about half its
weight is carbon, and half oxygen
and hydrogen, in almost the same
proportion as in water. It contains
also about 1 part in 100, by weight,
of earthy constituents, and nitrogen
to the same amount. When wood is
burned, all these materials disappear
into the air except the earthy con-
stituents. Xow the nitrogen and
water taken up by the roots were
originally in the air before they
reached the ground. It is true, there-
fore, that when wood is burned those
l)arts of it which came from the air
go back into it in the form of gas,
came from the soil remain behind in

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Fig. 11.— Wood and bark
of the Western Yellow-
Pine. The cut is per
pendicular, and tlie
specimen stands as it
did in the tree. The
])ictnro shows the di-
vision of the bark into
scales by the succes-
sive layers of cork
cambium. Tlie true
cauibium is between
wood and hark.

while those which
the form of ashes.

Bui. 24, Div. of Forestry, U. S Dept. of Agr

Stem and Crown of a Forest Tree in British India.

The stem is about ihree feet in diameter.

THE BBEATHINa OF A TREE.

15

HOAV THE TREE BREATHES.

Besides giving out oxygen iu assimilation, trees also
take ill oxygen from the air through their leaves, and
through the minute openings in the bark called leiiticels,
such as the oblong raised spots or marks on the young

Fm. 12.— Wood and bark
of the Westeru Yellow
Pine. The cnt is a
cross section and
would I'.ave been hor-
izontal as the speci-
men stood in the tree.
Besides tlie division
of the bark into scales
this picture shows
twoof thedeepcracks
in the bark, at the bot-
tom of which lenticels
are placed.

Fig. 13.— Bark of the Westeru Yellow
Pine. Outer surface, showing the
scales made by the successive layers
of cork cambium.

branches of Bin^h and Cherry and
many other trees. All plants, like
all animals, breathe; and plants, like
animals, breathe in oxygen and
breathe out carbonic acid gas. This
process of respiration or the breathing
of the tree goes on both day and night,
but it is far less active than assimila-
tion, which takes place only in the light. Consequently
more carbonic acid gas is taken into the tree than is
given out, and the surplus carbon remains to be used
in growing.

16

A PRIMER OF FORESTRY.

TRANSPIRATION.

The leaves give out not only the oxygen derived from
the decomposition of carbonic acid gas taken from the

air and carbonic acid

gas produced inbreath-
ing, but also great quan-
tities of water vapor.
The amount of water
taken up by the roots is
very much larger than
is required to be com-
bined with carbon and
the earthy constituents
in the leaves. In order
that fresh supplies of

Fig. 14.— By ooniparing tin's diagram with
Pla. VII-IX and fig. 16, the phice of each
cut in the tree will be made clear.

earthy constituents in solution may reach the leaves
rapidly, the water already in them must be got out of
the way. This is effected by
transpiration, which is the evap-
oration of water from all parts of
the tree above ground, but princi-
pally from the leaves. Even
where the bark is very thick, as
on the trunks of old Oaks and
Chestnuts, transpiration goes on
through the lenticels in the bot-
toms of the deep cracks. It
sometimes happens, especially in
spring before the leaves come
out, that transpiration can not
get rid of the water from the roots

as fast as it rises, and that it falls in drops from the
buds, or later on even from the leaves themselves.

Fig. 15. — Top of a common
cork, slightly moistened to
bring out th(3 lines of annual
growth, which are rather
unusually plain in thisspeci-
men.

Bui. 24, Div. of Forestry, U. S. Dept of Agr

TRANSPIRATION.

17

FlQ. 16.— Wood of the Eastern Sycamore or Button-ball tree.

Fig. 17. — Cross section thnmuh a Black Oak. Milt'oni, I'a. The silver grain,
the rings of annual growth, and the dark heart wood and lighter sap wood are
visible, and the line between the rough corky outer bark and the thinner and
lighter-colored inner bark inav be seen.

18

A PRIMER OF 1 ORESTHY.

THE GROWTH OF A TREE.

The addition of new material in the way described in
the preceding pages is the foundation of growth. Ex-
cept in the buds, leaves, fruit, and the twigs less than
a year old, this material is deposited in a thin coat over
the whole tree between the wood and the bark. The
new twigs grow in length by a kind of stretching, but
only during the lirst year. Thus it is only by means of

these youngest twigs that a
tree increases in height and
in spread of branches. After
the first year their length is
fixed, younger twigs stretch
out from the buds, and the
older ones grow henceforth
only in thickness. (See fig.
9.) The fresh coat of new
material mentioned above
covers them year by year.
There are two layers in this
coat, separated by a third
one of tender forming tissues
called the cambium, in which the actual making of the
new substance goes on. The inner side of the cambium
layer forms new wood, the outer side new bark. Be-
sides the true cambium, which forms both wood and
bark, there is another cambium which makes the corky
outer bark, and nothing else. This cork cambium may
encircle the whole tree, like the true cambium, as in the
Red Cedar, or it may form little separate films in the
bark, but in either case it dies from time to time, and
is re-formed nearer the wood. (See figs. 10-13 and Pis. Y
and Yl.)

Fig. 18.— Cross section of a fallen
Black Oak. Milford, Pa. The
slabs shown in figs. 19 and 22 were
sawed lengthwise from this tree,
beginning where the black lines
are seen on the cross section.

Bui. 24, Div. of Forestry, U S. Dept. of Agr,

THE FORMATION OF WOOD.
THE STRUCTURE OF WOOD.

19

Wood is cliieily made up of very small tubes or cells
of various kinds, which have special uses in the life of
the tree. Some conduct water from the roots to the
crown, some store away digested food, and others merely
strengthen the structure of the wood and hold it to-
gether. The wood of cone-bearing or coniferous trees

I^G. 19.— Slab sawed length-wise from a Black Oak. Milford, Pa. The saw
passed about midway between the center of the tree and the bark. Tlie line
between tlie heartw^ood and the sap is plainly shown.

(like the Pines and Spruces) has but few kinds of
cells, while that of the broadleaf trees (such as Oaks and
Maples) is much less simple. ( See figs. 14, 16, 20, and Pis.
VIl-IX.) But in each case some of the cells have thick
walls and small openings, and others wide openings and
very thin walls. In climates which have regularly one

20

A PRIMER OF FORESTRY.

season of growth and one of rest,
like our own, the cells of the layer
of new wood formed each year
at the inner surface of the cam-
bium are arranged in a definite
way. When growth begins in the
spring, and the fresh twigs and
leaves put out, there is a great
demand for water in the crown
to supj)ly these moist green new
parts of the tree. Water rises in
most trees through the newer lay-
ers of the wood, and especially
through the last ring. Conse-
quently, at first the tree makes
thin walled cells with wide open-,
ings, through which water can
rise rapidlj^ to the ends of the
branches. Later on, when the de
mand for water is not so great,
and there is plenty of digested
food to supply building material,
the cells formed are narrow and
thick-walled. (See fig. 20.) Thus
the summer wood in each year's
growth is heavier, stronger, and
darker in color than the sirring
wood. In the wood of many
broadleaf trees, such as Oak and
Chestnut, the spring wood is also

Fig. 20. — Wood of a Spruce, i i i i t n . ■,

greatly magnified. marked by a band of open tubes

(From Hartig. . Anatomie of larger size Called ducts. In

und Phvsiologie der Pfian- i -««- ,

zen, Berlin, 1891.) others, such as Maple and Beech,

Bui. 24, Div. of Forestry, U. S. Dept of Agr

Plate VII.

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Wood of the White Pine.

THE FORMATION OF WOOD.

21

these ducts are scat-
tered tlirough tlie
whole season's growth,
and in all conifers, as
for example the Pines
and Cedars, they are
entirely wanting.
But the differences in
hardness and color
between the growth
of spring and summer
are still present. It
is sometimes possible
to see the line ^vhich
separates the growth
of two seasons in the
bark, as in the case of
common cork, which
is the outer bark of
the Cork Oak, a na-
tive of southern Eu-
rope. (See fig. 15.)

If the trunk or
branch of an Oak
tree is cut smoothly
across, thin whitish
lines may be seen run-
ning from within out-
ward. Some of these
lines begin in the cen-
ter of the tree, and
others in each one of
the annual rings.

Fig. 21.— a sectiou of the counuou Staghorn
Suinach, showing the darkened heartwood,
the white sapwood, and the inner and outer
bark. Dark coloring matter is often de-
posited in the heartwood, as in the case lieie
shown. Milford, Pa.

22

A PRIMER OF FORESTRY.

These are the medulhiry rays, which make the silver
grain in quartered Oak and other woods. (See figs. 17,
19, 22, and Pis. VII-IX.) They exist in all kinds of
trees, but in many, as, for example, in the Chestnut and
in most conifers, they are so line as hardly to be seen

Fig. 22.— Slab sawea lengthwise I'lom a Black Oak. Millurd, Pa. The saw-
passed almost through the center of the tree, but not quite. The lines of an-
nual growth are cut through obliquely, and the silver grain appears quite
plainly, both in the middle and at the sides.

with the naked eye. Seasoning cracks which run across
the rings of growth always follow the lines of these rays,
while others most often follow along some annual ring.

ANNUAL RINGS.

It is correct to speak of these rings of growth as
"annual rings,'' for as long as the tree is growing
healthily a ring is formed each year. (See figs. 17, 22, and

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Wood of the Red Oak.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate IX.

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HEARTWOOD AND SAPWOOD. 23

Pis. VII-X.) It is true that two false rings may appear
in one year, bat they are generally so much thinner
than the rings on each side that it is not hard to detect
them. Yery often they do not extend entirely around
the tree, as a true ring always does if the tree is sound.
Whenever the growth of the tree is interrui)ted and
begins again during the same season, such a false ring
is formed. This happens when the foliage is destroyed
by caterpillars and grows again in the same season, or
when a very severe drought in early summer stops
growth for a time, and in similar cases.

HEARTWOOD AND SAPWOOD.

An annual layer once formed does not change in size
or place during the healthy life of the tree, except that
it is covered in time by other younger layers. A nail
driven into a tree 6 feet from the ground will still be
at the same height after it is buried under 20 or 50 or
100 layers of annual growth. But in most trees, like the
Oaks and Pines, the wood becomes darker in color and
harder after it has been in the tree for some years. The
openings of its cells become choked so that the sap can
no longer run through them. From living sapwood, in
which growth is going on, it becomes heartwood, which
is dead, because it has nothing to do with growth. (See
figs. 19, 21.) It is simply a strong framework which helps
to support the living parts of the tree. This is why hol-
low trees may flourish and bear fruit. Sapwood rots
more easily than heartwood, because it takes up water
readily and contains plant food, which decays very fast.
Not all trees have heartwood, and in many the differ-
ence in color between it and the sapwood is very slight.
Since water from the roots rises only in the sapwood, it

24

A PRIMER OF FORESTRY.

is easy to kill trees with heartwood by girdling them,
provided all the sapwood is cut through. But in those
which have no heartwood the tubes of the older layers
of wood can still convey water to the crown, and when
such trees are girdled it is often several years before
they die.

A great many theories have been j^roposed to account
for the rise of water into the tops of tall trees, some of
which, as in the big trees of California, may be over
300 feet from the ground. But none of these theories
are quite satisfactory, and it must be admitted that we
do not yet know how the trees supply their lofty
crowns with the water which keeps them alive.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr,

Bui. 24, Div. of Forestry, U. S. Dept of Agr.

CHAPTER II.

TREES IN THE FOREST.

The nature of a tree, as shown by its behavior in the
forest, is called its silvicultural character. It is made
up of all those qualities upon which the species as a
whole, and every individual tree, depends in its strug-
gle for existence. The regions in which a tree will live,
and the places where it will flourish bestj the trees it
will grow with, and those which it kills or is killed by;
its abundance or scarcity; its size and rate of growth —
all these things are decided by the inborn qualities, or
silvicultural character, of each particular kind of tree.

THE VARIOUS REQUIREMENTS OF TREES.

Diflerent sj^ecies of trees, like different races of men,
have special requirements for the things upon which
their life depends. Some races, like the Eskimos live
only in cold regions. (See PI. XI.) Others, like the
South Sea Islanders, must have a very warm climate
to be comfortable, and are short-lived in any other. (See
fig. 23.) So it is with trees, except that their different
needs are even more varied and distinct. Some of
them, like the Willows, Birches, and Spruces of north-
ern Canada, stand on the boundary of tree growth
within the Arctic Circle. Other species grow only in
tropical lands, and can not resist even the lightest
frost. (See PI. XII.) It is always the highest and low-
est temperature, rather than the average, which decides
where a tree will or will not grow. Thus the average
temperature of an island where it never freezes may be

25

26

A PRIMER OF FORESTRY.

only COO, while another place, with an average of 70o, may
have occasional frosts. Trees which could not live at all
in the second of these places, on account of the frost,
might flourish in the lower average warmth of the first.
In this way the bearing of trees toward heat and
cold has a great deal to do with their distribution over
the surface of the whole earth. Their distribution
within shorter distances also often depends largely
upon it. In the United States, for example, the Live

Oak does not grow
in Maine, nor the
Canoe Birch in Flor-
ida. Even the op-
posite sides of the
same hill may be
covered with two
different species, be-
cause one of them
resists the late and
early frosts and the
fierce midday heat
of summer, while the other requires the coolness and
moisture of the northern slope. (See fig. 24.) On
eastern slopes, where the sun strikes early in the day,
frosts in the spring and fall are far more apt to kill
tlie young trees, or the blossoms and twigs of older
ones, than on those which face to the west and north,
where growth begins later in the spring, and where
rapid thawing, which does more harm than the freez-
ing itself, is less likely to take place.

REQUIREMENTS OF TREES FOR HEAT AND MOISTURE.

Heat and moisture act together upon trees in such a
way that it is sometimes hard to distinguish their

Fig. 23,— a forest of Palms in southern Florida.

Bu

24, Div, of Forestiy, U. S. DepT. of Agr.

Plate XII.

A Teak Forest in British India.

The Teak tree yields one of the most durable and valuable kinds of tinnber, especially
adapted to shipbuilding, but it will not grow where there is the slightest frost. Its
durability is shown by the condition of the old stump, from which the large tree on
the left grew as a sprout.

REQUIREMENTS FOR HEAT AND MOISTURE. 27

effects. A dry country, or a dry slope, is apt to be hot as
well, while a cool northern slope is almost always moister
than one turned toward the south. Still the results
of the demand of trees for water can usually be distin-

JtL

fk

i

in

I

1

Fig. 24.— The Black Hemlock in its home. Cascade Mountains of Washington.

guished from the results of their need of warmth, and
it is found that moisture has almost as great an influ
ence on tlie distribution of trees over the earth as heat
itself. Indeed, within any given region it is apt to be

28

A PRIMER 0;F forestry.

much more conspicuous, and the smaller the region the
more noticeable often is its effect, because the contrast
is more striking. Thus it is frequently easy to see the
difference between the trees in a swamj) and those on a
dry hillside near by, when it would be far less easy to
distinguish the general character of the forest which
includes both swamp and hillside from that of another

Fig. 25.— Cypress in a hollow. Pine on the slightly higher land near by. Wet
weather spring, Southern Georgia.

forest at a distance. (See fig. 25.) In many instances
the demand for water controls distribution altogether.
For this reason the forests on the opposite sides of
mountain ranges are often composed of entirely differ-
ent trees. On the west slope of the Sierra Nevada
of California, for example, where there is plenty of
moisture, there is also one of the most beautifuU of
all forests. (See fig. 26 and PI. XIII.) The east

24, Div. of Forestry, U. S Dept. of Agr

PLATE XIII.

REQUIREMENTS FOR HEAT AND MOISTURE. 29

slope, on the contrary, has almost no trees, because
its rainfall is very slight, and those which do grow
there are small and stunted in comparison with the
giants on the west. (See PI. XI Y.) Again, certain
trees, like the Bald Cypress and the River Birch, grow
only in very moist land; others, like the Mesquite and
the Pinyon or Nut Pine, only on the driest soils; while

Fig. 26.— Dense forest in a region of great rainfall. Olympic Peninsula, Wash-
ington.

still others, like the Red Cedar and the Red Fir,
seem to adapt themselves to almost any degree of
moisture, and are found on very wet and very dry
soils alike. In this way the different demands for
moisture often separate the kinds of trees which grow
in the bottom of a valley from those along its slopes,
or even those in the gullies of hillsides from those on

30

A PRIMER OF FORESTRY.

Fig. 27.— Light crown of
an intolerant tree, the
Western Larch. The
tree with heavy foli-
age and horizontal
branches in the back-
ground to the right is a
Western White Pine,
a tolerant species.
Northern Idaho.

the rolling land between. (See PI.
XV.) A mound not more than a
foot above the level of a swamp is
often covered with trees entirely
different from those of the wetter
lower land about it.

Such matters as these have far
more to do with the places in which
different trees grow than the chemi-
cal composition of the soil. But its
mechanical nature— that is, whether
it is stiff or loose, fine or coarse in
grain, deep or shallow — is very im-
portant, because it is directly con-
nected with heat and moisture and
the life of the roots in the soil.

REQUIREMENTS OF TREES FOR
LIGHT.

The relations of trees to heat and
moisture are thus largely responsible
for their distribution upon the great
divisions of the earth's surface, such
as continents and mountain ranges,
as well as over the smaller rises and
depressions of every region where
trees grow. But wh ile heat and mois-
ture decide where the different kinds
of trees can grow, their influence has
comparatively little to do with the
struggles of individuals or species
against each other for the actual pos-
session of the ground. The outcome of
these struggles depends less on heat

Bui. 24, Div. of Forestry, U S. Dept of Agr.

Plate XIV.

REQUIREMENTS FOR LIGHT.

31

and moisture than on the possession of certain qualities,
among which is the ability to bear shade. With regard
to this power trees are roughly divided into two classes,
often called shade-bearing and light-demanding, follow-
ing the German, but better named tolerant and intoler-
ant of shade. (See figs. 27, 28.) Tolerant trees are those
which flourish under more or less heavy shade in early

Fig. 28.

-Heavy crowns of a tolerant species.
Washington.

The Alpine Fir in northern

youth; intolerant trees are those which demand a com-
paratively slight cover, or even unrestricted light.
Later in life all trees require much more light than at
first, and usually those of both classes can live to old
age only when they are altogether unshaded from above.
But there is always this difference between them : the
leaves of tolerant trees will bear more shade. Oonse-

32

A PRIMER OF FORESTRY.

quently those on the lower and iimer parts of the crowu
are more vigorous, plentiful, and persistent than is

the (5ase with intoler-
ant trees. Thus the
crown of a tolerant
tree in the forest is
usually denser and
longer than that of
one vhicli bears less
shade„ It is usually
true that the seed-
lings of trees with
dense crowns are able
to flourish under
cover, while those of
light-crowned trees
are intolerant. This
rough general rule is
often of use in the
study of forests in a
new country, or of
trees whose silvicul-
tural character is not
known.

TOLERANCE AND IN-
TOLERANCE.

Fig. 29.— A. small Ked Spruce in the Adiron-
dack Mountains of New York. For many
years this tree stood under the dense cover
of taller trees. During that time its branches
spread to the sides, but it made scarcely any
growth in height. Then more light came to
it, ])robably by the fall of some tall neighbor,
and it began to recover its strength and grow
much faster. The thin upper part of the
crowu is where this faster height growth has
been going on.

The tolerance or in-
tolerance of trees is
one of their most im-
portant silvicultural
characters. Frequently it is the first thing a forester
seeks to learn about them, because what he can safely

Bui. 24, Div. of Forestry, U. S Dept. of A?r.

Plate XV.

TOLERANCE AND INTOLERANCE.

33

undertake in the woods depends so largely upon it.
Thus tolerant trees will often grow vigorously under
the shade of light- crowned trees above them, while if
the positions were
reversed the latter
would speedily die.
(See PI. XYl.) The
proi)ortion of differ-
ent kinds of trees in
a forest often depends
on their tolerance.
Thus Hemlock some-
times replaces White
Pine in Pennsylvania,
because it can grow
beneath the Pine, and
so be ready to fill the
opeuing whenever a
Pine dies. But the
Pine can not grow
under the Hemlock,
and can only take
possession of the
ground when a fire

or a windfall makes ^^^' ^^-""^ Pitch Pine, producing seed abun-

. dantly, as shown by the numerous cones, but

an opening where it with no seedlings beneath it. Fire has run

can have plenty of <>ver the ground, and the surface is very dry.

,. , ^2 -^ strong breeze was blowing when the pic-

llgnt. toOme trees, ture was taken. New Jersey.

after being over-
shaded, can never recover their vigor when at last they
are set free. Others do recover and grow vigorously
even after many years of starving under heavy shade.
The Eed Spruce, in the Adirondacks, has a wonderful

34

A PRIMER OF FORESTRY.

FiQ.31.— Win<;ed seeds: l,Basswood; 2, 13oxelder; 3, Elm; 4, Fir; 5 to 8, Pine.

Fig. 32.— Cones: Beginning at the left, these cones come from Coulter's Pine,
the Western White Pine, the Eastern White Pine, the Knob-Cone Pine, the
Fox-Tail Pine, the Pitch Pine, the Lodgepole Pine, tlie Red Fir, the Short-
leaf Pine, the Eastern Hemlock, and the Eastern Arbor Vitie.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr

A Group of Hemlocks and Rhododendrons growing in the Shade of Oaks and
Chestnuts. Milford Pa.

TOLERANCE AND INTOLERANCE.

35

power of this kind, and makes a line tree after spend-
ing the first fifty or even one hundred years of its
life in reaching a diameter of a couple of inches. (See
fig. 29.)

The relation of a tree to light changes not only
with its age, but also with the place where it is grow-
ing, and with its health. An intolerant tree will stand

1 ■■• :^^%^^^ te

r;wf*; §^

Fici. 3;{. — Young Oaks staitiug under an old forest of Pines.

Carolina.

Eastern North

more cover where the light is intense than in a cloudy
northern region, and more if it has plenty of water
than with a scanty supply. Vigorous seedlings will
get along with less light than sickly ones. Seedlings
of the same species will prosper under heavier shade
if they have always grown under cover than if they
have had plenty of light at first and have been de-
prived of it afterwards.

36

A PRIMER OF FORESTRY.

THE RATE OF GROWTH.

The rate of growth of differeut trees often decides
which one will survive in the forest. For example, if
two intolerant kinds of trees should start together on a
burned area or an old field, that one which grew faster
in height would overtop the other and destroy it in the
end by cutting off the light. Some trees, like the
Black Walnut, grow rapidly from their earliest youth.

Fig. 34.— Pure forest ofWesteni YcIIons" J'iuc in the Black Hills of South Da-
kota. The trees here are smaller in size tliau those of Montana (see fig. 35),
but their power of reproduction is much greater.

Others grow very slowly for the first few years. The
stem of the Longleaf Pine, at 4 years old, is usually
not more than 5 inches in length. During this time
the roots have been growing instead of the stem. The
period of its rapid growth in height comes later.

The place where a tree stands has a great influence
on its rate of growth. Thus the trees on a hillside are
often much smaller than those of equal age in the rich

Bui 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XVII.

m%^ "^.^

s

f

^r

■-«v

HE^

z
m

ip

'*• "* ■

^^^^^^HP^^Ri

B^^BhCiMF ra ^...

i

-^

; JS^_^,. "~ Ili^^^-^^^H

g

,^^^1^ i^JH^Bj

\

'' -'^^^f!

.^'■•'fi. '-^^^^M

H

i

s

8

|MV~->-^^^<^

I

■-.•.

^^^^MBI\ ^

o

%•

^BhL

^

9P9^nil^B^i^4%>

REPRODUCTIVE POWER OF TREES.

37

hollow below, and those on the upper slopes of a high
mountain are commonly starved and stunted in com-
parison with the vigorous forest lower down. (See PI.
XVII.) The Western Chinquapin, which reaches a
height of 15(1 feet in the coast valleys of northern
California, is a mere shrub
at high elevations in the
Sierra Nevada. The same
thing often appears in passing
from the more temperate re-
gions to the far north. Thus
the Canoe Birch, at its north-
ern limit, rises only a few
inches above the ground,
while farther south it becomes
a tree sometimes 120 feet in
height.

THE REPRODUCTIVE POWER
OF TREES.

Another matter which is of
the deepest interest to the fig. ^s.-westem Yeiiow Pin. m

mixture with other trees. I'lat-
forester is the reproductive head Valley, Montana.

power of his trees. Except

in the case of sprouts and other growth fed by old
roots, this depends first of all on the quantity of the
seed which each tree bears; but so many other con-
siderations affect the result that a tree which bears seed
abundantly may not reproduce itself very well. (See
fig. 30.) A part of the seed is always unsound, and
sometimes much the larger part, as in the case of the
Tulip Tree. But even a great abundance of sound seed
does not always insure good reproduction. The seeds

38

A PRIMER OF FORESTRY.

may not find the right surroundings for successful ger-
mination, or the infant trees may jjerish for want of
water, light, or suitable soil. Where there is a thick
layer of dry leaves or needles on the ground, seedlings
often perish in great numbers because their delicate
rootlets can not reach the fertile soil beneath. The
same thing happens when there is no humus at all and
the surface is hard and dry. The weight of the seed
also has a powerful influence on the character of repro-
duction. Trees with
heavy seeds, like
Oaks, Hickories,
and Chestnuts, can
sow them only in
their own neighbor
hood, except when
they stand on steep
hillsides or on the
banks of streams,
or when birds and
squirrels carry the
nuts and acorns to
a distance. (See PI.
XVIII.) Trees with
light, winged seeds, like the Poplars, Birches, and
Pines, have a great advantage over the others, be-
cause they can drop their seeds a long way off. (See
figs. 31, 32.) The wind is the means by which this is
brought about, and the adaptation of the seeds them-
selves is often very curious and interesting. The wing
of a Pine seed, for example, is so placed that the seed
whirls when it falls, in such a way that it falls very
slowly. Thus the wind has time to carry it away before
it can reach the ground. In lieavy winds Pine and other

f ■-■-

i M

■

tt

':--%^3^^

^Hlil

Fig. 36. Mixed forest of White Pine, Chestnut,
and Oak at Milford, Pa.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XVIll.

SUCCESSION OF FOREST TREES.

39

winged seeds are blown long distances— sometimes as

much as several miles.

This explains how certain
kinds of trees, like the
Gray Birch and the White
Pine, grow up in the mid-
dle of open pastures, and
how others, such as the
Lodgepole Pine, cover
great areas, far from the
parent trees, with young
growth of even age.

THE SUCCESSION OF
FOREST TREES.

Such facts help to ex-
plain why, in certain
places, it happens that
when Pines are cut down
Oaks succeed them, or
when Oaks are removed
Pines occupy the ground.
It is very often true that
young trees of one kind
are already growing un-
noticed beneath old trees

of another, and so are ^^«- 37.-Pure forest of white Cedar

near Toms River, New Jersey.

ready to replace them

whenever the upper story is cut away. (See fig. 3.'3.)

Ill-:

If]

■HEjMpwLgy

■w-

I:

•i

;''■•-

''^^^

PURE AND MIXED FOREST.

The nature of the seed has much to do with the distri-
bution of trees in pure or mixed forest. It is the habit
of some trees to grow in bodies of some extent contain-

40

A PRIMER OF FORESTRY.

iiig only a single kind; in other words, in pure forest.
(See fig. 34 and PI. XIX.) The Longleaf Pine of the
South Atlantic and Gulf States is of this kind, and
so is the Lodgepole Pine of the West. Conifers are

more apt to grow in pure
forest than broadleaf trees,
because it is more common
for them to have winged
seeds. The greater i)art of
the heavy- seeded trees in
the United States are de-
ciduous, and most of the
deciduous trees grow in
mixed forest, although there
are some conspicuous excep-
tions. But even in mixed
forests small groups of trees
with heavy seeds are com-
mon, because the young trees
naturally start up beneath
and around the old ones.
A heavy seed, dropping from
the top of a tall tree, often
strikes the lower branches
in its fall and bounds far out-
side the circle of the crown.
Trees which are found only,
or most often, in pure forest
are the social or gregarious
kinds; those which grow in mixture with other trees
are called scattered kinds. Most of the hardwood for-
ests in the United States are mixed ; and many mixed
forests, like that in the Adirondack?, contain both broad-

PlG. 38.— Sprouts of Gray Birch
with a small White Oak in the
foreground. Milford, Pa.

Bui. 24, Div. of Forestry, U. S. Dept. of Ag

Pure Forest of Young Red Fir. Western Oregon.

Except in parts of Washington and Oregon, the Red Fir is less often found pure than
in mixture with other trees. It is one of the nnost valuable tinnber trees of the wotid,
and is very widely distributed in the Western States. On the northern part of tlie
Pacific slope it is very abundant and of great size, and Its wood is widely used, both at
honr.e and abroad, under the nnisleading nanne of Oregon Pine.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr

O >

z o

Bui. 24, Div. of Forestry, U. S Dept. of Agr.

"^v^Zx-"'!^ . -^M^^ w f ' ^k^^Bt^M

^^ /[ '>r^^^''^\l'' Jr "^'^^B* ''~*''^^*^^^B^B^w

r.'^W- /-'^'^"^^v^ '^1 "-^^MB^^

g y-'-"" ¥ bV^ '.Mw • ^"■'■^■^^BBHay^^S

"N. t >^ i ''9 — ^I^B. W - '/^^^^^RS^

^JLpy^^^ - .J^M^ M >-x ■ ■^K l!'Mk^i^'',^l^^'^BBP^>?^8

/ - 'P^- ^^^^^mIS

/ ^^fe

f^'^'^IW^'^I^^Ql

' ^^K

ft^i^K[9^SiH

w%^^-'^ « upghf^jB^BPyffiw ^B'^'' nB^^BI^^l^SBiH

wsr'* "imL' ^ifej^^HoHilSH^^^SI^r^ - ''*"'' ■PS*- T"--'7iiifw^SKBHB^B^BH'Tf'

mH^^I^^v ^^m^^^BW^^pHi^ fft^BWji^iWim

u^BpStw '" i^SMtwtiP|i!7'"^'^^^^irT 1 y^|^M^„^jBWHi

r»^^JS^^' . - .^.'ijl^BMH

■BKjJr'j^BliB iL^mBmct '^

J^-^:%,r-i.^ ^' ^■. , .>. ■'■ v/ -,•

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k'.-:^'^'^^

C^."> %:4'i^.'i^

■^-'fi^i>' ':'^^'^''"' /^■^'•^'f. "r^fc

i'-r>^! A ■' *fk' ,.li ,.J«

IMS^^^i^ H ■»!%»& ^':'.,is|*.is^# Mi^^

HW^^^^^MHB

'^i^mmm^ssB^^^--^

BK!^^^^i'lHB^tet^W'^s>'^i^^'W< ' ""^^ ^"'' "^

HKw^^^^i ^Bwl^^^'w^^y^^^p^^" .-.k*!*

^^dj^SBJaBa^^ ^^flfrC •^^^v^^^^^RJ^i^^ '■''fHiWl^m-

^^W^^^^^Pyf«^ > ^p^!^^^^^^^H|^^^^

^^^^^^^^^o^ ! ^^" ;r ^^^

^^ j^K^n^Kf^ . ^ \ -- ''«sBi™|

^^mtjii^A.. . M

Mixed Forest in the Adirondack Mountains, New Yori<
UNDER Older Spruce, Birch, anc

A Group of Young Spruces
Maple.

In the foreground are many young broadleaf seedlings. The Adirondack forest contains
Beech, Birch, Maple, Cherry, and Poplar annong the broadleaf trees, and Pine, Spruce,
Hemlock, Larch, Fir, and Cedar among the cone bearers.

PURE AND MIXED FOREST.

41

leaf trees and conifers. (See fig. 36 and Pis. XX, XXI.)
The line between gregarious and scattered species is not
always well marked, because it often happens that a
tree may be gregarious in one place, and live with many
others elsewhere. The Western Yellow Pine, which
forms, on the plateau of central Arizona, perhaps the
largest pure Pine for-
est of the earth, is
frequently found
growing with other
species in the moun-
tains, especially in
the Sierra Xevada of
central California.
(See figs. 34, 35.)

Trees which oc-
cupy the ground to
the exclusion of all
others do so because
they succeed better,
under the condi-
tions, than their com-
petitors. (See fig.
37.) It may be that
they are able to get
on with less water, or

to grow on poorer soil, their rate of growth or power of re-
production may be greater, or there may be some other
reason why they are better fitted for their surroundings.
But the gregarious trees are not all alike in their ability
to sustain themselves in different situations, while the
differences between some of the mixed-forest species
are very marked indeed. Thus Black Walnut, as a

Fig. 39,— Sprouts of Pitch Pine from the neigh-
borhood of Toms Kiver, New Jersey.

42

A PRIMER OF FORESTRY.

rule, grows only in rich moist soil, and Beech only in
damp situations. Fire Cherry, on the other hand, is
most common on lands which have been devastated by
fire, and the Rock Oak is most often found on dry bar-
ren ridges. The Tupelo or
Black Gum and the Red
Maple both grow best in
swamps, but it is a common
thing to find them also on
dry stony soils at a distance
from water. The knowledge
of such qualities as these is
of great importance in the
management of forest lands.

REPRODUCTION BY
SPROUTS.

Besides reproduction from
seed, which plays so large
a part in the struggle for
the ground, reproduction by
sprouts from old roots or
stumps is of great impor-
tance in forestry. (See fig.
38.) Trees differ very nuich
in their power of sprouting. In nearly all conifers ex-
cel )t t^i^ California coast Redwood, which has this ability
beyond almost every other tree, it is lacking altogether.
The Pitch or Jack Pine of the Eastern United States
has it also to some extent, but in most places the
sprouts usually die in early youth, and seldom make
merchantable trees. (See fig. 39 and PI. XXII.) In the
broadleaf kinds, on the other hand, it is a general and

EiG. 40.— Chestnut sprouts from
the stump. Milford, Pa.

Bui. 24, Div of Forestry, U. S Dept. of Ag

Suckers, or Sprouts, from the Trunk and Branches of a Pitch Pine.
Southern New Jersey.

A year before the picture was taken a forest fire passed over this place and burned to the
top of the tree, destroying^ all the needles ; yet, the tree was not killed, although
scarcely any other kind could have survived. It put out a vigorous growth of suckers,
and it still has a chance for life. Such examples are common throughout the burnt
parts of southern New Jersey, where large and vigorous sprouts from the roots of trees
of this species which have been killed to the ground by fire are very frequent.

REPRODUCTION RY SPROUTS.

43

very valuable quality. Youug stumps, as a rule, are
much more productive than old ones, although some
l)rolific species, like the Chestnut (see fig. 40), sprout
plentifully in old age. Other species, like the Beech,
furnish numerous sprouts from young stumps and very
few or none at all from old ones, and still others never
sprout freely even in early youth.

CHAPTER III.

THE LIFE OF A FOREST.

The history of the life of a forest is a story of the
help and harm which the trees receive from one another.
On one side every tree is engaged in a relentless strug-
gle against its neighbors for light, water, and food, the
three things trees need most. On the other side, each
tree is constantly working with all its neighbors, even
those which stand at some distance, to bring about the
best condition of the soil and air for the growth and
fighting power of every other tree. (See PI. XXIII.)

A COMMUNITY OF TKEES.

The life of a community of trees is an exceedingly
interesting one. A forest tree is in many ways as much
dependent upon its neighbors for safety and food as are
the inhabitants of a town upon one another. (See fig.
41.) The difference is that in a town each citizen has a
special calling or occupation in which he works for the
service of the commonwealth, while in the forest every
tree contributes to the general welfare in nearly all the
ways in which it is benefited by the community. A
forest tree helps to protect its neighbors against the
wind, which might overthrow them, and the sun, which
is ready to dry up the soil about their roots or to make
sun cracks in their bark by shining too hotly upon it.
It enriches the earth in Avhich they stand by the fall of
44

Bui. 24, Div. of Forestry, U. S. Dept. of Agr

Plate XXIll.

S 2

3 ?>

c

g Z

A COMMUNITY OF TREES.

45

its leaves and twigs, aud aids in keeping the air about
their crowns, and the soil about their roots, cooler in
summer and warmer in winter than it would be if each
tree stood alone. (See PI. XXIV.) With the others it
forms a common canopy under which the seedlings of
all the members of this protective union are sheltered
in early youth, and through which the beneficent influ-

FiG. 41.— A forest in Switzerland where the mutual help of the trees is at its
best. The Sihlwald, where this picture was taken, has been well managed
Hiiice before the discovery of America

ence of the forest is preserved and extended far beyond
the spread of the trees themselves. But while this
fruitful cooperation exists, there is also present, just
as in a village or a city, a vigorous strife for the good
things of life. For a tree the best of these, and often
the hardest to get, are water for the roots and space and
light for the crown. In all but very dry places there is

46

A PRIMER OR FORESTRY

water eiiougii for all the trees, and often more than
enough, as for example in the Adirondack forest. The
struggle for space and light is thus more important
than the struggle for water, and as it takes place above
ground it is also much more easily observed and stud-
ied. (See fig. 42 and PI. XXY.)

Light and space are of such importance because, as

we have seen, the leaves
can not assimilate or di-
gest food excej^t in the
presence of light and air.
The rate at which a tree
can grow and make new
wood is decided chiefly by
its ability to assimilate
and digest plant food.
This power depends upon
the number, size, and
health of the leaves, and
these in turn upon the
amount of space and light
which the tree can secure.

if

1 > 1 —

■yb'^f*-!

■ ''---^U-

Si't^ll

THE

LIFE OF A
CROP.

FOREST

Fig. 42.— On the edge of a very dense
forest. The leaning trees are dead,
killed by the crowding and shade of
their stronger neighbors. Spruce in
the White Mountains, New Hamp-
shire.

The story of the life of
a forest crop is then largely an account of the cora-
l)etition of the trees for light and room, and, although
the very strength which enables them to carry on
the fight is a result of their association, still the
deadly struggle, in which the victims are many times
more in number than those which survive, is apt
alone to absorb the attention. Yet the mutual help
of the trees to each other is always going quietly on.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XXIV.

THE SEVEN AGES OF A TREE.

47

Every tree coiitiimally comforts and assists the other
trees, which are its friendly enemies.
(See fig-s. 43,44.)

The purpose of the present chapter
is to follow the progress of a forest
crop of uniform age from the seed
through all the successive phases of
its life until it reaches maturity, bears
seed in its turn, and finally declines
in fertility and strength until at last
it passes away and its place is filled
by a new generation. The life his-
tory which we are about to follow,
as it unfolds itself through the course
of several hundred years, is full of
struggle and danger in youth, restful
and dignified in age. The changes
which pass over it are vast and full
of the deepest interest, but they are
very gradual. From beginning to
end one stage melts insensibly into
the next. Still, in order to study and
describe them conveniently, each
stage must have limits and a name.

THE SEVEN AGES OF A TREE.

A very practical way of naming
and distinguishing trees is the follow-
ing, which will be used in referring
to them hereafter in this discussion.
Young trees which have not yet
reached a height of 3 feet are seed-
lings. (See figs. 45-49 and Pis.
XXyil, XXVIII.) They are called

Fig. 43.— a forest tree,
deprived of its com-*
panions, slowly dy-
ing. A Larch in the
Priest River Forest
Reserve, Idaho.

48

A PRIMER OF FORESTRY.

seedlings in si)ite of the fact that any tree, of whatever
age, if it grew from a seed, is properly called a seedling
tree. Trees from 3 to 30 feet in height are small sap-
lings, and from 10 feet in
height until they reach
a diameter of 4 inches
they are large saplings.
(See figs. 50, 51, 57.)
Small poles are from 4
to 8 inches iu diameter.

Fig. 44.— Forest trees standing too far
apart to help each other. Lake
Chelan, Washington.

and large poles from 8 to 12
inches in diameter. (See figs.
54, 55,andri. XXIX.) Trees
from 1 to 2 feet through are
standards, and finally, all
trees over 2 feet in diameter
are veterans. (See figs. 34,
56, and Pis. I, XXXI,

Fig. 45.— a White Pine seedling,
showing the slender roots. Mil-
ford, Pa.

XXXII.)

It is very important to re-
member that all these diam-
eters are measured breast high, or at the height of a
man's chest, about 4 feet 6 inches from the ground. In
forestry this is, roughly speaking, the general custom.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XXV.

THE BEGINNING OF A FOREST CROP. 49

HOW THE CROP BEGINS.

Let US imagine an abundaut crop of tree seeds lying
on the ground in the forest. (See PI. XXVI.) How
they came there does not interest us at present; we
do not care to know whether they were carried by the
wind, as often happens with the winged seeds of many
trees, such as Pines and Maples, or whether the squir-

FlG. 46.

-Seedlings of Western Hemlock growing thickly on a fallen log.
Western Washington.

rels and birds dropped and planted some of them, as
they frequently do acorns and chestnuts, or whether the
old trees stood closely about and sowed the seed them-
selves. We will only suppose them to be all of one kind,
and to be scattered in a place where the soil, the mois-
ture, and the light are all just as they should be for
their successful germination, and afterwards for the

50

A PRIMER OF FORESTRY.

later stages of their lives. Even under the best condi-
tions a considerable part of the fallen seed may never
germinate, but in this case we will assume that half of it
succeeds. (See fig. 4().)

As each seed of our forest germinates and pushes its
first slender rootlet downward into the earth, it has a
very uncertain hold on life. Even for some time after-

FiG. 47. — Seedlings of Wliite Pine under a spreading Scrub Oak. Miltbrd, Pa.
The young Pines are overshaded by the worthless Oak, and will die unless
the latter is cut away.

wards the danger from frost, dryness, and excessive
moisture is very serious indeed, and there are many
other foes by which the young seedlings may be over-
come. It sometimes happens that great numbers of
them perish in their earliest youth because their roots
can not reach the soil through the thick dry coating of
dead leaves which covers it. But our young trees pass
through the beginning of these dangers with compara-

Bui. 24, Div of Forestry, U. S. Dept. of Agr.

Plate XXVI.

THE FOREST COVER ESTABLISHED.

51

lively little loss, and a plentiful crop of seedlings occu-
pies the ground. As jet, however, each little tree
stands free from those about it. As yet, too, the life
of the young forest may be threatened or even de-
stroyed by any one of the enemies already mentioned,
or it may suffer just as severely if the cover of the
older trees above it is too dense. In the beginning of
their lives seedlings often require to be protected by

Fig. 48.— Young "White Pines (seedlings) whose lower hranches have ju."-t be-
gun to interfere. Milford, Pa. These are vigorous young trees, with i^leuty
of light, as may be seen by the grass which is growing around them. Grass
in the woods almost always means that the cover is too thin for the good of
the soil.

the shade of their elders, but if this protection is too
long continued they suffer for want of light, and are
either killed outright or live only to drag on stunted
and unhealthy lives. (See fig. 47.)

THE FOREST COVER ESTABLISHED.

The crop which we are following has had a suitable
proportion of shade and light during its earliest years,
and the seedlings have spread until their crowns begin
to meet. Hitherto each little tree has had all the space
in the air and soil that it needed for the expansion of
its top and roots. This would have been entirely good,
except that meanwhile the soil about the trees has been

52

A PRIMER OF FORESTRY.

more or less exposed to the sun and wind, and so
has become dryer and less fertile than if it had been
under cover, and consequently the growth has been
slow. But now that the crowns are meeting, the situa-
tion becomes wonderfully changed. The soil begins
to improve rapidly, because it is protected by the
cover of the meeting crowns and enriched by the

leaves and twigs which
fall from them. (See figs.
48,49.)

THE BEGINNINd OF THE
STRl'GGLE.

In SO far the condi-
tions of life are better,
and in consequence the
growth, and more espe-
cially the height growth,
begins to show a marked
increase. (See fig. 50.)
On the other hand, all the
new strength is in im-
mediate demand. With
the added vigor which the trees are now helping each
other to attain comes the most urgent need for rapid
development, for the decisive struggle is at hand.
The roots of the young trees contend with each other
in the soil for moisture and the plant food which it
contains, while in the air the crowns struggle for
space and light. The latter is by far the more im-
portant battle. The victors in it overcome by greater
rapidity of growtli at the ends of the branches, for it
is by growth there, and there only, that trees increase

Fig. 49.— Grouj) of White Pines (siual
saplings) in an openinfj among older
trees. Milford, Pa. Tlie lower
branches are crowding each otlier
vigorously, and will soon begin to die.

Bui. 24, Div. of Fo'estry, U. S Dept of Agr.

P.ATE XXVII.

BEGINNING OF THE STRUGGLE.

53

in height aud spread of crown. Growth in this way
was going on unchecked among the young trees be-
fore the crowns met, but now only the uj^ward-grow-
ing branches can develop freely. The leaves at the
ends of the side branches have now less room and, above
all, less light, for they are crowded and thrust aside by
those of the other trees. Very often they are bruised
by thrashing against
their neighbors when
the wind blows, or
even broken off while
still in the bud.
Leaves exposed to
such dangers are un-
healthy. They tran-
spire less than the
healthy, undisturbed
leaves of the upper
part of the crown,
and more and more
of the undigested
food from the roots
goes to the stronger
leaves at the top
as the assimilating
power of the side
leaves dwindles with the loss of light. The young
branches share the fortunes of their leaves and are vigor-
ous or sickly according to the condition of the latter. For
this reason the growth of the tops increases, while that of
the lower lateral branches, as the tops cover them with a
deeper and deeper shade, becomes less and less. Gradu-
ally it ceases altogether, and the branches perish. This

Fig. 50.— Small saplings of White Pino grow-
ing thickly together. Milford, Pa. The
space between each cluster or whorl of side
branches marks one year's growth. These
young Pines are beginning to grow rapidly
in height because they can no longer spread
at the sides.

54

A PRIMER OF FORESTRY.

process is called natural pruniug, and from the time
when it begins the existence of the young forest, unless

it should be overtaken bj^
fire or some other great
calamity, is practically se-
cure.

GROWTH IN HEIGHT.

At this time, as we have
seen, the crowns of all the
young trees are growing
faster at the tops than at the
sides, for there is unlimited
room above. (See fig. 51.)
But some are growing faster
than others, either because
their roots are more devel-
oped or in better soil than
those of tiie trees about
them, because the}^ have
been freer from the attacks
of insects and other ene-
mies, or for some similar
reasons. Some trees have
an inborn tendency to grow
faster than others of the
same species in the same
surroundings, just as one

Fig. 51. — Large saplings and small . /? -i • n,

poles. Western Larch and Western SOU lU a family IS oftCll

W^hite Pine. Priest Kiver Forest taller tliau tllC brothers witll

Reserve, Idaho. ^^^^^^^ j^^ ^^^ brOUght Up.

Eapid growth in height, from whatever cause it i^ro-
ceeds, brings not only additional light and air to the

Bu.. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XXVIII.

GROWTH IN HEIGHT.

55

tree which excels in it, but also the chance to spread
laterally, and so to complete the defeat of its slower
rivals by overtopping them.

■^

Fig. 52. Fig. 53.

A tall clear trunk made by natural pruning, anil the base of the saiue tree.
Sitka Spruce in the Olympic Forest Eeserve, Washington.

56

A PRIMER OF FORESTRY.

THE STRUGGLE CONTINUED.

Fig. 54. — Natural pruning on Pine poles
still uutiuished. Biltmore, N. C.

Those trees which have
gained this advautage
over their neighbors are
called dominant trees,
while the surviving lag-
gards in the race are said
to be overtopped when
they are hopelessly be-
hind, and retarded when
less badly beaten. Enor-
mous numbers of seed-
lings and small saplings
are suppressed and killed
during the early youth of
the forest. In the young
crop which we are fol-
lowing many thousands
perish upon every acre.
Even the dominant trees,
which are temporarily free
when they rise above their
neighbors, speedily come
into conflict with each
other as they spread, and
in the end the greater
portion is overcome. It
is a very deadly strug-
gle, but 3'ear by year the
differences between the
trees become less marked.
Each separate individual
clings to life with greater
tenacity, the strife is more

Jul. 24, Div. of Forestry, U. S. Dept. of Agr

A Forest of Spruce Poles. Adirondack Mountains, New York.

A STRIFE FOR SURVIVAL.

57

protracted and severe, and tlie number of trees which
perish grows rapidly smaller. But so great is the pres-
sure when dense groups of young trees are evenly
matched in size and rate of growth that it is not very
unusual to find the progress of the young forest in its

FiQ. 55.— Poles of Longleaf Pine. Southern Florida.

early stages almost stopped, and the trees uniformly
sickly and undersized, on account of the crowding.

The forest we have been following has now passed
through the small-sapling stage, and is composed chiefly,
but not exclusively, of large sai)lings. Among the over-

58

A PRIMER OF FORESTRY.

topped and retarded trees, wbicli often remain in size
classes which the dominant trees have long since

outgrown, tliere are
still many low saiilings.
Even between the domi-
nant trees, in a healthy
forest, there are always
great differences. In-
crease in height is now
going on rapidly among
these high saplings, and
either in this stage or
the next a i^oiiit is
reached when the top-
most branches make
their longest yearly
growth, which is one
way of saying that the
trees make their most
rapid height growth as
large sapliugs or small
poles. (See PI. XXIX.)
Later on, as we shall see,
these upper branches lengthen much more slowly, until,
in standards and veterans, the growth in height gradu-
ally diminishes, and in very old trees finally ceases
altogether.

NATURAL PRUNING.

While the trees are pushing up most rapidly the side
branches are most quickly overshaded, and the process
of natural pruning goes on with the greatest vigor.
Natural pruning is the reason why old trees in a dense
forest have only a small crown high in the air, and why
their tall, straight trunks are clear of branches to such

Fig. 56.— Standards and poles of Spruce.
White Mountains, New Jliinipshire.

Bui. 24,

Imperfect Natural Pruning on a White Pine that stood too much alone in Early
Youth. Milford, Pa.

NATURAL PRUNING.

59

ji height above the ground. (See figs. 52-5G and PI.
XXX.) The trunks of trees grown in the open, where
even the lower limbs have abundance of light, are
branched either quite to the ground or to within a short
distance of it. But in the
forest not only are the lower
side branches continually-
dying for want of light, but
the tree rids itself of them
after they are dead and so
frees its trunk from them en-
tirely. When a branch dies
the annual layer of new wood
is no longer deposited upon
it. Consequently the dead
branch, where it is inserted
in the tree, makes a little
hole in the first coat of living
tissue formed over the live
wood after its death. The
edges of this hole make a
sort of collar about the base
of the dead branch, and as
a new layer is added each
year they press it more and
more tightly. So strong does this comi)ression of the
living wood become that at last what remains of the
dead tissue has so little strength that the branch is
broken off by an ice storm or by the wind, or even falls
of its own weight. Then in a short time, if all goes
well, the hole closes, and after a while little or no ex-
terior trace of it remains. Knots, such as those which
are found in boards, are the marks left in the trunk
by branches which have disappeared.

Fig. 57.— Pointed crowns of saplings
of LongleafPiue growing rapidly
in height. Southern Florida.

60

A PRIMER OF FORESTRY.

THE CULMINATION OF (IROWTH.

Fig. 58.-
tened c

—An old Longleaf Pine with tiat-
rown. Eastern North Carolina.

While the young trees
are niaking clean trunks
so rapidly during- the pe-
riod of greatest yearly
heiglit growth they are
also making their great-
est annual gains in diam-
eter, for these two forms
of growth generally cul-
minate about the same
time. A little later, if
there is any difference,
the young forest's highest
yearly rate of growth in
volume is also reached.
For a time these tliree
kinds of growth keep on
at the same rate as in the
past, but afterwards all
three begin to decrease.
Growth in diameter, and
in volume also, if the
trees are sound, goes on
until extreme old age, but
height growth sinks very
low while the two others
are still strong. For
many years before this
hapi^ens the struggle be-
tween the trees has not
been so deadly, because
thev have been almost

Bui. 24, DIv. of Forestry, U. S. Dept. of Agr.

Plate XXXI.

A Dense Forest of Standards and Veterans of Red Fir and Lov^/land Fir.
Lake Crescent, Ol>mpic Peninsula, Washington.

THE END OF THE STRUGGLE.

61

without the means of overtopping one another. When
the end of the period of principal height growth is
reached the trees are interfering with each other very
little, and the struggle for life begins again in a differ-
ent way. As the principal height growth ceases, and
the tops no longer shoot up rapidly above the side
branches, the crowns lose their
pointed shape and become com-
paratively flat. (See figs. 57, 58.)
The chief reason why trees stop
growing in height is that they are
not able to keep the upper i)arts
of their crowns properly supplied
with water above a certain dis-
tance from the ground. This
distance varies in different kinds
of trees, and with the health and
vigor of the tree in each species,
but there is a limit in every case
above which the water does not
reach. The power of the pumping machinery, more than
any other quality, determines the height of the tree.

Fig. 59.— Diagram to show
why a sharply conical
crown receives more light
than a flat one.

THE END OF THE STRUGGLE.

Now that the tree can no longer expand at the top,
it must either suffer a great loss in the number of its
leaves or be able to spread at the sides; for it is clear
that not nearly so many leaves can be exposed to the
light in the flattened crown as in the pointed one, just
as a pointed roof has more surface than a flat one.
(See fig. 59.) It is just at this time, too, that the trees
begin to bear seed most abundantly, and it is of the
greatest importance to each tree that its digestive appa-

62

A PRIMER OF FORESTRY.

ratusin the leaves should be able to furnish a large sup-
l)ly of digested food. Consequently the struggle for
space is fiercely renewed, only now the trees no longer
attemx)t to overtop one another, having lost the powei',
but to crowd one another away at the sides. (See fig. CO.)
The whole forest might suffer severely at this jwint from
a deadlock such as sometimes happens in early youth

Fig. 60.— White Pine standards in the Adirondack Mountains, New Yoik.

were it not for the fact that the trees, as they grow
older, become more and more sensitive to any shade.
Many sj^ecies which stand crowding fairly well in youth
can not thrive in age unless their crowns are completely
free on every side. Each of the victors in this last
phase of the struggle is the survivor of hundreds (or
sometimes even of thousands) of seedlings. Among

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XXXII.

THE END OF THE STRUGGLE.

63

very numerous competitors tliey have sliowu themselves
to be the best adapted to their surroundings. (See fig.
Gl and PI. XXXI.)

Xatural selection has made it clear that these are the
best trees for the place. These are also the trees which
bear the seed Avhence the younger generations spring.
Their offspring will inherit their fitness to a greater or
less degree, and in their turn will be subjected to the

Fig. 61.— An open forest of intolerant Lougleaf Pine. Southern Florida.

same rigorous test, by which only the best are allowed
to reach maturity. Cnder this sifting out of the weak
and the unfit, our native trees have been prepared,
through thousands of generations, to meet the condi-
tions under which they must live. This is why they
are so much more apt to succeed than species from
abroad, which have not been fitted for our climate and
soil by natural selection.

04 A PRIMER OF FORESTRY.

Tlie forest which we saw first in the seed has now
passed througli all the more vigorous and active stages
of its life. The trees have become standards and vet-
erans, and large enough to be valuable for lumber.
Rapid growth in height has long been at an end, diam-
eter growth is slow, and the forest as a whole is increas-
ing A^ery little in volume as time goes on. The trees
are ripe for the harvest.

Out of the many things which might happen to our
mature forest we will only consider three.

DEATH FROM WEAKNESS AND DECAY.

In the first place, we will suppose that it stands un-
touched until, like the trees of the virgin forest, it meets
its death from weakness and decay.

The trees of the mature primeval forest live on, if no
accidents intervene, almost at peace among tliemselves.
At length all conflict between them ends. The whole
power of each tree is strained in a new struggle against
death, until at last it fails. One by one the old trees
disappear. But long before they go, the forerunners of
a new generation have sprung up wherever light came
in between their isolated crowns. As the old trees
fall, with intervals, often of many years, between their
deaths, young growth of various ages rises to take their
])lace, and when the last of the old forest has vanished
tliere may be differences of a hundred years among
the young trees which succeed it. (See PI. XXXII.)
An even-aged crop of considerable extent, such as we
have been considering, is not usual in the virgin forest,
where trees of very different ages grow side by side,
and when it does occur, the next generation is far less
uniform. The forest whose history has just been sketched

Bui. 24, Div.of Foreslry, U. S. Dept. of Agr

Plate XXXIII.

Forest on the South Fork of the Flathead River, Montana.
All the stages of tree growth are often present m one place, as here.

DESTRUCTIVE LUMBERING.

65

was chosen, not because it represents the most common
type of natural forest, but because it illustrates better
than any other the life and progress of forest growth.
(See PI. XXXIII.)

The wood of a tree which dies in the forest is almost
wholly wasted. For a time the rotting trunk may serve
to retain moisture, but there is little use for the carbon,
oxygen, and hydro-
gen which make up
its greater part. The
mineral constituents
alone form a useful

fertilizer, but most
often there is al-
ready an abundance
of similar material
in the soil. Not only
is the old tree lost,
but ever since its ma-
turity it has done lit-
tle more than intercept, to no good purpose, the light
which would otherwise have given vitality to a valuable
crop of younger trees. It is only when the ripe wood
is harvested properly and in time that the forest attains
its hiohest usefulness.

Fig. (J'J.— Liiiiibeied antl binned forest near
Port Crescent, 01ym])ic Peninsula, Wash-
iugton.

DESTRUCTIVE LUMBERING.

A second thing which may happen to a forest is to be
cut down without care for the future. The yield of a
forest lumbered in the usual way is more or less thor-
oughly harvested, it is true, but at an enormous cost to
the forest. Ordinary lumbering injures or destroys the
young growth, both in the present and for the future.

6() A PRIMER OF FORESTRY.

provokes and feeds fires, and does harm of many other
kinds. In many cases its result is to annihihite the
productive capacity of forest land for tens or scores of
years to come. (See fig. G2 and PI. XXXIV.)

CONSERVATIVE LUMBERING.

The methods of forestry, on the other hand, maintain
and increase both the productiveness and the capital
value of forest land; harvest the yield far more com-
jdetely than ordinary I umberino, although less rapidly;
prepare for, encourage, and preserve the young growth;
tend to keep out fires; and in general draw from the
forest, while protecting it, the best return which it is
capable of giving.

The application of these methods is the third possi-
bility for the crop Just described. There are still many
places in the United States where transportation is so
costly that, as yet, forestry will not pay from a business
l)oint of view. Elsewhere right forest management is
the wisest, safest, and most satisfactory way of dealing
with the forest. It is briefly described in Part II of
this primer.

Bui. 24, DIv. of Forestry, U. S. Dept. of Agr,

Plate XXXIV.

CHAPTER IV.

ENEMIES OF THE FOREST.

The forest is threatened by many enemies, of which
fire and reckless lumbering are the worst. In the
United States sheep grazing and wind come next. Cat-
tle and horses do much less damage than sheep, and
snow break is less costly than windfall. Landslides,
floods, insects, and fungi are sometimes very harmful.
In certain situations numbers of trees Jire killed by light-
ning, which has also been known to set the woods on
fire, and the forest is attacked in many other ways.
For example, birds and squirrels often prevent young
growth by devouring great quantities of nuts and otiier
seeds, while porcupines and mice frequently kill young
trees by gnawing away their bark.

:\rAN AND NATURE IN THE FOREST.

Most of these foes may be called natural enemies, fur
they would injure the forCvSt to a greater or less extent
if the action of man were altogether removed. Wild
jininials would take the place of domestic sheep and
cattle to some degree, and fire, wind, and insects would
still attack the forest. But many of the most serious
dangers to the forest are of human origin. Such are
destructive lumbering, and excessive taxation on forest
lands, to which much bad lumbering is directly due.
So high are these taxes, for in many cases they amount
to 5 or even 6 per cent yearly on the market value of

67

68

A PRIMER OF FORESTRY.

the forests, that the owners can not afford to i^ay
them and hold tlieir hmds. Consequently they are
forced to cut oi* sell their timber in haste and with-
out regard to the future. When the timber is gone
the ownervS refuse to pay taxes any longer, and the
devastated lands revert to the State. Many thou-
sand square miles of forest have been ruined by reck-

FiG. 63.— A burnt forest in the Priest Kiver Forest Reserve, Idaho

less lumbering because heavy taxes forced the owners
to realize quickly and once for all upon their forest land,
instead of cutting it in a way to insure valuable future
crops. For the same reason many counties are now
poor that might, with reasonable taxation of timber
land, have been flourishing and rich.

A short description of destructive lumbering will be

Bui. 24, Div of Forestry, U. S. Dept. of Agr

Plate XXXV.

GRAZING IN THE FOREST.

C9

found ill Part II of this primer, together with some
consideration of the most effective remedy, which is
found in conservative ways of handling the forest,
that is, in forest management.

GRAZING IN THE FOREST.

Whether grazing animals are comparatively harmless
to the forest or among its most dangerous enemies

Fig. 64.— a band of sheep passing through the forest. These sheep were being
heided illegally iu a forest reserve. Eastern slope of the Cascade Mountains
near Badger Lake, Wasco County, Oregon.

depends on the age and character of the woods as well
as upon the kind of animals that graze. A young forest
is always more exposed to such injury than an old one,
and steep slopes are more subject to damage than more
level ground. Whether the young trees are conifers,
and so more likely to suffer from trampling than from

70

A PRIMER OF FORESTRY

being eaten, or broadleaf trees, and so more likely to
be devoured, they should be protected from pasturing
animals until they are large enough to be out of danger.

GRAZING AND FIRE.

Grazing in the forest does harm in three ways. Tirst,
it is a fertile cause of forest fires, (See figs. 04-00 and
PI. XXXV.) Burning the soil cover of grass and other

I ■

M'

,

^ .-e^

^^^B3Bm:f

1

M

\ %

^^^^^^••w

1

1

S

f j^pMHiHtiltti«ii«iH

^^

wm

^H

Fig. 65.

-A forest of Lodgepole Pine in a region used for grazing.
Forest Reserve, Wyoming.

Bighorn

])lants improves the grazing, either permanently, by
destroying the forest and so extending the area of pas-
turage, or temi^orarily, by improving the quality of the
feed. For one or the other of these objects, but chiefly
for the latter, vast areas are annually burned over in
nearly every part of the United States where trees grow.
The great majority of these fires do not kill the old
trees, but the harm they do tlie forest and, eventually.

Bui

, 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XXXVI.

TRAMPLING BY SHEEP.

71

the fodder i^lants themselves, is very serious indeed.
The sheej) men of the West are commonly accused of
setting many forest fires to improve the grazing, and
they are also vigorously defended from this charge.
But the fact remains that large areas where sheep now
graze would be covered with forests except for the
action of more or less recent fires.

■:s

l^..^,*^^!*

Fig. 66.— Cattle in the Bighorn Forest Reserve, Wyoming.

TRAMPLING.

Trami^ling is the second way in which grazing ani-
mals injure the forest. Cattle and horses do compara-
tively little harm, although their hoofs compact the soil
and often tear loose the slender rootlets of small trees.
Sheep, on the contrary, are exceedingly harmful, espe-
cially on steep slopes and where the soil is loose. In
such places their small, sharp hoofs cut and powder the
soil, break and overthrow the young trees, and often
destroy promising young forests altogether. (See Pis.

72 A rUIMKR OF FORESTRY.

XXXYI, XXXVII, XXXVIir.) lu mauy places tlio
eflbct of the trampliug is to destroy the forest floor and
to interfere very seriously with the flow of streams. In
the Alps of southern France sheep grazing led to the
destruction, first, of the mountain forests, and then of
the grass which had replaced them, and thus left the
soil fully ex])osed to the rain. Great floods followed,
beds of barren stones w^ere spread over the fertile flelds
by the force of the water, and many rich valleys were
almost or altogether dejwimlated. Besides the loss
occasioned in this way, it has cost the French people
tens of millions of dollars to repair the dainage begun
by the sheep, and the task is not yet flnished. The loss
to the nation is enormously greater than any gain from
the mountain pastures could have been, and even the
sheep owners themselves, for whose profit the damage
was done, were losers in the end, for their industry in
that region was utterly destroyed.

:?ROWSIN(l.

The third way in which grazing animals injure the
forest is by feeding on the young trees. In the western
part of the United States, where most of the forests
are evergreen, this is far less important than the dam-
age from either fire or trampling, for sheep and other
animals seldom eat young conifers if they can get other
food. Even where broad leaf trees prevail browsing
rarely leads to the destruction of any forest, although
it commonly results in scanty young growth, often
maimed and unsound as w^ell. Goats are especially
harmful, and where they abound the healthy reproduc-
tion of broad leaf trees is i^ractically impossible. In
the United States they are fortunately not common.
Cattle devour tender young shoots and branches in vast

Bui. 24, Div. of Forestry, U. S. Dept of Agr.

Plate XXXVII.

FOREST INSECTS.

73

quantities, often living for months on little else, and
sheep are destructive in the same way. Hogs also find
a living in the forest, but they are less harmful,
because a large part of their food consists of seeds and
nuts. East of the Great Plains very large numbers of
cattle and hogs are turned into the woods, but sheep
grazing in the forest is most widely developed in the
West, and especially in California, where it should be

Fig. 67. — Larch trees killed by the larva of a small sawfly. The land has just
been lumbered for Spruce. Adirondack Mountains, New York.

prevented altogether, in Oregon and Washington, where
it should be regulated and restricted, and in some
interior regions, like Wyoming and New Mexico, where
it should be rigidly excluded from all steep mountain
regions, and carefully regulated on more level ground.

FOREST INSECTS.

Insects are constantly injuring the forest, just as year
by year they bring loss to the farm. Occasionally their

74

A PRIMER OF FORESTRY.

ravages attain enormous proportions. Thus a worm,
whicli afterwards develops into a sawfly, has since 1882
killed nearly every full-grown Larch in the Adirondacks
by eating away the leaves. ( See fig. G7.) Even the small

and vigorous Larches do
not escape altogether from,
these attacks. Conifers,
such as the Larch and
Spruce, are nuich more
likely to sutfer from the
attacks of insects than
broadleaf trees. About
the year 187G small bark
beetles began to kill the
mature Spruce trees in
the Adirondacks, and ten
years later, when the
worst of the attack was
X^ast, the forest was practi-
cally deprived of all its
largest Spruces. This
pest is still at work in northern Kew Hampshire and in
Maine.

FOREST FUNGI.

Pungi attack the forest in many ways. Some kill
the roots of trees, some grow upward from the ground
into the trees and change the sound wood of the trunks
to a useless rotten mass, and the minute spores (or seeds)
of others float through the air and come in contact with
every external part of the tree above ground. (See fig.
C8.) Wherever the wood is exposed there is danger
that spores will find lodgment and breed disease. This

Tig. 68.— Rotting wood from an old Red
Fir stub. The young Hemlock to the
right began life on the bark of the
Fir. Olympic Forest Heserve, Wash-
ington.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XXXVIII.

WIND ]N THE FOREST.

75

is a strong reasou why all wounds, such as those made
in pruning, should be covered with some substance like
paint or tar to exclude the air and the spores it carries.

WIND IN THE FOREST.

The effect of wind in the virgin forest is not wholly
injurious. Although in many regions it overthrows
jrreat numbers of old trees, their removal is usually fol-

FlG. 69.— A windfall in the Olympic Fig. 70. — In the same windfall. Olympic
Forest Reserve, Washington. Forest Reserve, Washington.

lowed by a vigorous young growth where the old trees
stood. (See PL XXXIX.) In this way the wind hel])S to
keep the forest full of young and healthy trees. But it
also breaks and blows down great numbers of useful
growing members of the forest. Much of this windfall
occurs among shallow-rooted trees, or where the ground
is soft because soaked with water, or where the trees
have been weakened by unsoundness or fire. Some

76

A PROIER OF FORESTRY.

storms are stroii<>' enough to break the trees they can
not overtlirow. Damage from wind is not uncommon
in many parts of the United States, and in phices the

Joss from iti is very serious.
(See (igs. 69, 70.) Xear
the town of High Springs,
for examph^, in Alachua
County, Fla., in a region
very subject to such acci-
dents, there is a tract of
many square miles, once
covered with Longleaf
Pine, over which i)racti-
cally all the trees were
killed by a great storm sev-
eral years ago. Some were
thrown Hat, some were so
racked and so broken'in the
top that they died, and very
many were snapped off* at

FIG. 71.-A young Spruce loaded with ^0^^ ^^ ^O 30 feet above the
snow. Avalanche Lake, Adirondack grOUnd. There IS little
Mountains, New Vork. ^^^^ -^ ^^^^^^ prCCautioUS

against such great calamities, yet the loss from windfall
may be very much reduced by judicious cutting. An
unbroken forest is least exposed.

SNOW IN THE FOREST.

Snow often loads down, breaks, and crushes tall
young trees, especially if wet snow falls heavily be-
fore the broadleaf trees have shed their foliage in the
fall. Such injury is difficult to guard against, bat it
is well to know tliat very slim, tall trees suffer more
than those whose growth in diameter and height have

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XXXIX.

Young Spruces and Pines springing up in a Windfall.
Adirondack Mountains, New York.

FOREST FIRES.

77

kept better pace with each other. (See figs. 71, 72, and
PI. XL.) In many regions snow is so useful in protect-
ing the soil and the young trees that the harm it does
is quite overbalanced by its benefits.

FOREST FIRES.

Of all the foes wliich attack the woodlands of [N^orth
America no other is so terrible as fire. Forest fires
spring from many differ-
ent causes. They are often
kindled along railroads by
sparks from the locomo-
tives. Carelessness is re-
sponsible for many fires.
Settlers and farmers clear-
ing land or burning grass
and brush often allow the
fire to escai^e into the
woods. (See fig. 73.)
Some one may drop a half-
burned match or the glow-
ing tobacco of a pipe or
cigar, or a hunter or
prospector may neglect to
extinguish his camp fire,
or may build it where it
will burrow into the thick
duft" far beyond his reach,

to smolder for days, or weeks, and perhaps to break
out as a destructive fire long after he is gone. Many
fires are set for malice or revenge, and the forest is often
burned over by huckleberry pickers to increase the next
season's growth of berries, or by the owners of cattle
or sheep to make better pasture for their herds.

Fig. 72.— a young Red Fir bent down by-
snow in early youth. It is scarred by
fire on tlie underside. Washington
I'orest Eeserve.

78 A PKIMER OF FORESTRY.

There is danger froiri forest fires in tlie dry portions
of tbe spring- and summer, but tliose wliicli do most
harm usually occur in the fall. At whatever time of
the year they appear, their destructive power depends
very much on the wind. They can not travel against
it except when burning up hill, and not even then if
the wind is strong. The wind may give them strength

Fig. 73. — A clearing in Spruce timber. The great cost and difficulty of such
clearing is well illustrated. In the foreground is a held of potatoes. Olympic
Forest Keserve, Washington.

and si^eed by driving them swiftly through unburned,
inflammable forests, or it may extinguish the fiercest
fire in a short time by turning it back over its path,
where there is nothing left to burn. In fighting forest
fires the wind is always the first thing to consider, and
its direction must be carefully watched. A sudden

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

c o

^ CO

IT- I

I i

HISTORIC FOREST FIRES. 79

change of wind may check a fire, or may turn it off in
a new direction and i)erhaps threaten the lives of the
men at work by driving it suddenly down upon them.

HISTORIC FOREST FIRES.

When all the conditions are favorable, forest fires
sometimes reach gigantic proi3ortious. A few such
fires have attained historic importance. One of these
is the Miramichi fire of 1825. It began its greatest

Fig. 74.— a forest fire on the Yukon River, Alaska. Bow of a canoe to the left.

destruction about 1 o'clock in the afternoon of October
7 of that year, at a place about GO miles above the town
of Newcastle, on the Miramichi River, in New Bruns-
wick. Before 10 o'clock at night it was 20 miles below
Newcastle. In nine hours it had destroyed a belt of
forest 80 miles long and 25 miles wide. Over more than
two and a half million acres almost every living thing
was killed. Even the fish were afterwards found dead
in heai^s on the river banks. Five hundred and ninety
buildings were burned, and a number of towns, includ-

80

A PRIMER OF FORESTRY.

ing Newcastle, Chatham, and Douglastowii, were de-
stroyed. One hundred and sixty persons perished, and
nearly a thousand head of stock. The loss from the
Miramichi fire is estimated at $300,000, not including
the value of the timber.

Fig. 75. — Fire sometimes renews an old forest by killing the veterans and so
permitting vigorous young trees to take their place. Tlie rotting stubs of
fire-killed veterans of Ited Fir are seen in the picture surrouuded by young
standards of Red Fir and AVestern Hemlock. Olympic Forest Keserve,
Washington.

In the majority of such forest fires as this the destruc-
tion of the timber is a more serious loss, by far, than
that of the cattle and buildings, for it carries with it
the impoverishment of a whole region for tens or even
hundreds of years afterwards. The loss of the stumpage
value of the timber at the time of the fire is but a small

Bui. 24, Div. of Forestry, U. S. Dept. of Agr

Plate XLI.

HISTORIC FOREST FIRES. 81

I>art of I lie daraage to the iieigliborliood. The wages
that would have been earned in lumbering, added to
the value of the i^roduce that would have been i^ur-
chased to supply the lumber camps, and the taxes that
would have been devoted to roads and other public
improvements, furnish a much truer measure of how

Fig. 76. — A llocky Mountain coniferous forest killed by tire. Valley of the
North Fork of Suu Kiver, Montana.

much, sooner or later, it costs a region when its forests
are destroyed by fire. (See figs. 76-81, and Pis. XLI,
XLVI, XlViI.)

The Peshtigo lire of October, 1871, was still more
severe than the Miramichi. It covered an area of over
2,000 square miles in Wisconsin, and involved a loss,
in timber and other property, of many millions of dol-
lars. Between 1,200 and 1,500 persons perished, includ-
ing nearly half the ])opulation of Peshtigo, at that time

82

A PRIMEll OF FORESTRY.

a towu of 2,000 inhabitants.

ITia. 77. — A burnt forest near Monte Criato
in the "Washinffton Forest Reserve.

feet board measure, and in
money over $10,000,000.
Several hundred persons per-
ished.

In the early i)art of Sep-
tember, 1881, great fires cov-
ered more than 1,800 square
miles in Aarious parts of
Michigan. The estimated
loss, in i)roperty, in addition
to many hundred thousand
acres of valuable timber,
was more than $2,300,000.
Over 5,000 persons were

Other tire.s of about the
same time were mcst
destructive in Michi-
gan. A strip about
40 miles wide ami
180 miles long, ex-
tending across the
central part of the
State from Lake
Michigan to Lake
Huron, was devas-
tated. The estimated
loss in timber was
about 4,000,000,000

made destitute, and the num-

ber of lives lost is variously
estimated at from 150 to 500.
The most destructive fire
of more recent years was
that which started near Hinckley, Minn., September 1,

Fig. 78.— a single Red Fir, spared
by the fire, remains to indicate
Avhat tlie burnt area is capable of
producing. Washington Forest
Reserve.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

3 5

f. r

p O

1 I

Bui. 24, Div. of Forestry, U. S. Dept. of Agr

Plate XLIII.

MEANS OF DEFENSE. 83

1894. While the area burned over was less than in
some other great fires, the loss of life and property was
very heavy. Hinckley and six other towns were de-
stroyed, about 500 lives were lost, more than 2,000 per-
sons were left destitute, and the estimated loss in prop-
erty of various kinds was $25,000,000. Except for the
heroic conduct of locomotive engineers and other rail-
road men the loss of life would have been far greater.
This fire was all the more deplorable, because it was
wholly unnecessary. For many days before the high
wind came and drove it into uncontrollable fury, it was
burning slowly close to the town of Hinckley, and
could have been put out.

MEANS OF DEFENSE.

The means of fighting forest fires are not everywhere
the same, for they burn in many different ways; but
in every case the best time to fight a fire is at the begin-
ning, before it has had time to spread. A delay of even
a very few minutes may permit a fire that at first could
easily have been extinguished to gather headway and
get altogether beyond control.

When there is but a thin covering of leaves and other
waste on the ground a fire usually can not burn very
hotly or move with much speed. The fires in most
hardwood forests are of this kind. They seldom kill
large trees, but they destroy seedlings and saplings
and kill the bark of older trees in places near the
ground. The hollows at the foot of old Chestnuts and
other large trees are often the results of these fires,
which occur again and again, and so enlarge the wounds
instead of allowing them to heal. (See PI. XLIl.)
Moderate fires also occur in dense coniferous forests

84

A PRIMER OF FORESTRY.

when only the top of a thick layer of duff is dry enough
to bum. The heat may not be great enough to kill any
but the smallest and tenderest young trees, but that
does not mean that such fires do no harm. The future
of the forest depends on just such young growth, and
whenever the forest floor, which is so necessary both

to the trees and for the
water supply, is injured or
destroyed by fire, the for-
est suffers harm.

SURFACE FIRES.

Surface fires may be
checked if they are feeble
by beating them out with
green branches, or by rak-
ing the leaves away from a
narrow strip across their
course. The best tool for
this purpose is a four-tined
pitchfork, or a common stable fork. In sandy regions
a thin and narrow belt of saud is easily and quickly
si^rinkled over the ground with a shovel, and will check
the spread of a weak fire, or even of a comparatively
hot one if there is no wind. Dirt or sand thrown on a
burning fire is one of the best of all means for putting
it out. (See fig. 79.)

In dense forests with a heavy forest floor, tires are
often hot enough not only to kill the standing timber,
but to consume the trunks and branches altogether,
and even to follow the roots far down into the ground.
In forests of this kind fire spreads easily, creeping along
on the surface or through the duff or under the bark

Fig. 79.— a surface fire burning slowly
against the wind. Southern New
Jersey.

Bui. 24, Div. of Foiestry, U. S. Dept. of Agr

Plate XLIV.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

Plate XLV.

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GROUND FIRES.

85

of rotting fallen trees. (See PI. XLIII.) In the same
way it climbs dead standing trees, and breaks oat in
bursts of flame higli in the air. Dead trees help ])ow-
erfully to spread a fire, for in high winds loose pieces of
their burning bark are carried to almost incredible dis-
tances, and drop into the dry forest far ahead, while in
calm weather they scatter
burning fragments all
about them when tliey
fall. (See lig. 80.)

GROUND FIRES.

When the duft* is very
deep or the soil peaty, a
fire may burn beneath the
surface of the ground for
weeks or even months,
sometimes showing its
presence by a little smoke,
sometimes without giving
any sign of life. Even a
heavy rain may fail to
quench a fire of this kind,
which often breaks out
again long after it is be-
lieved to be entirely extinct. Fires which thus burn into
the ground can sometimes be checked only by digging
a trench through the layer of decaying wood and other
vegetable matter to the mineral soil beneath. Ground
fires usually burn much more slowly than surface fires,
but they are exceptionally long lived, and very hard to
put out. It is of the first importance to attack such
fires quickly, before they have had time to burrow far

Fig. 80.— The effect of repeated fires.
Not only the old trees are dead, but
the seedlings which succeeded tliem
have perished also. Western Yellow
Pine in the Black Hills Forest Reserve,
South Dakota.

86

A PRIMKR OF FOBESTBY.

beneath tlie surface of tlie ground. Surface tires are
usually far less troublesome, but in either case fires
which kill the trees are generally repeated again and
again until the dead timber is consumed. (See fig. 81
and Pis. XLIYj XLV, XLYI, XLYII.)

BACK-FIRINa.

The most dangerous and destructive forest fires are
those which run both along the ground and in the tops

result of recvirriug fires. The forest fioor has disappeared aud
the pure white saiifl. Avhich looks like snow iu the picture, la left Avithout
protection. Southern Xew Jersey.

of the trees. When a fire becomes intensely hot on the
ground it may run up the bark, especially if the trees
are conifers, and burn in the crowns. Such fires are the
fiercest and most destructive of all. Traveling some-
times faster than a man can run, they consume enor-
mous quantities of valuable timber, burn fences, build-
ings, and domestic animals, and endanger or even
destroy human lives. They can be checked only by

Bui. 24, Div. of Forestry, U. S. Dept. of Agr. Plate XLVl.

Fallen and Standin3 Fire-killed Timber Ready for the Next Fire.
Priest River Forest Reserve, Idaho.

BACK-FIRING.

8'

rain or change of wind, or by meeting some barrier
which they can not i^ass. A barrier of this kind is often
made by starting another fire some distance ahead
of the principal one.
This back-fire, as it is
called, must be al-
lowed to burn only
against the wind and
toward tlie main fire,
so that when the two
fires meet both must
go out for lack of fuel.
To i)revent it from
moving with the wind,
a back-fire should al-
ways be started on the
windward side of a

road or a raked or sanded strip, or some other line which
it can be kept from crossing. (See fig. 82.) If it is al-
lowed to escape it may become as dangerous as the main

Fig. 82.— Setting a back-fire on the windward
side of a road. Southern New Jersey.
Drawn from a photograph.

Fig. 83. — A fire line along a railroad with two cleared spaces separated by a
double row of trees intended to catch the sparks.

fire itself. Back-fires are sometimes driven beyond con-
trol by a change of wind, but the chief danger from their
use is caused by persons who, in excitement or fright.

88

A PRIMER OF FORESTRY.

light them at the wrong time or in the wrong place.
Still, there is no otlier means of fighting tires so power-
ful, and none so effective when rightly used.

FIRE LINES.

Fire lines — strips kept free from all inflammable
material by burning or otherwise — are very useful in
checking small fires and of great value as lines of defense
in fighting large, ones. (See fig. 83.) They are also
very efi'ective in keeping tires out of the woods, as, for
example, along railroad tracks. But without men to
do tlie fighting they are of as little use against really
dangerous fires as forts without soldiers against invad-
ing armies.

END OF PART 1.

Bui. 24, Div. of Forestry, U. S. Dept. of Agr.

A Cedar Swamp after a Fire. Southern New Jersey.