Study I What Forestry Is And What It Does
Although Forestry is not a new idea but, as a science and an art, has
been applied for nearly two thousand years, there are many persons who
still need an explanation of its aims and principles.
Forestry deals with the establishment, protection and utilization of
forests.
By establishment, is meant the planting of new forests and the cutting
of mature forests, in such a way as to encourage a natural growth of new
trees without artificial planting or seeding. The planting may consist
of sowing seed, or of setting out young trees. The establishment of a
forest by cutting may consist of the removal of all mature trees and
dependence upon the remaining stumps to reproduce the forest from
sprouts, or it may consist of the removal of only a portion of the
mature trees, thus giving the young seedlings on the ground room in
which to grow.
By protection, is meant the safeguarding of the forest from fire, wind,
insects, disease and injury for which man is directly responsible. Here,
the forester also prevents injury to the trees from the grazing and
browsing of sheep and goats, and keeps his forest so well stocked that
no wind can uproot the trees nor can the sun dry up the moist forest
soil.
By utilization, is meant the conservative and intelligent harvesting of
the forest, with the aim of obtaining the greatest amount of product
from a given area, with the least waste, in the quickest time, and
without the slightest deterioration of the forest as a whole. The
forester cuts his mature trees, only, and generally leaves a sufficient
number on the ground to preserve the forest soil and to cast seed for
the production of a new crop. In this way, he secures an annual output
without hurting the forest itself. He studies the properties and values
of the different woods and places them where they will be most useful.
He lays down principles for so harvesting the timber and the
by-products of the forest that there will be the least waste and injury
to the trees which remain standing. He utilizes the forest, but does not
cut enough to interfere with the neighboring water-sheds, which the
forests protect.
Forestry, therefore, deals with a vast and varied mass of information,
comprising all the known facts relating to the life of a forest. It does
not deal with the individual tree and its planting and care,--that would
be arboriculture. Nor does it consider the grouping of trees for
aesthetic effect,--that would be landscape gardening. It concerns itself
with the forest as a community of trees and with the utilization of the
forest on an economic basis.
Each one of these activities in Forestry is a study in itself and
involves considerable detail, of which the reader may obtain a general
knowledge in the following pages. For a more complete discussion, the
reader is referred to any of the standard books on Forestry.
The life and nature of a forest: When we think of a forest we are apt to
think of a large number of individual trees having no special
relationship to each other. Closer observation, however, will reveal
that the forest consists of a distinct group of trees, sufficiently
dense to form an unbroken canopy of tops, and that, where trees grow
so closely together, they become very interdependent. It is this
interdependence that makes the forest different from a mere group of
trees in a park or on a lawn. In this composite character, the
forest enriches its own soil from year to year, changes the climate
within its own bounds, controls the streams along its borders and
supports a multitude of animals and plants peculiar to itself. This
communal relationship in the life history of the forest furnishes a
most interesting story of struggle and mutual aid. Different trees
have different requirements with regard to water, food and light.
Some need more water and food than others, some will not endure much
shade, and others will grow in the deepest shade. In the open, a
tree, if once established, can meet its needs quite readily and,
though it has to ward off a number of enemies, insects, disease and
windstorm--its struggle for existence is comparatively easy. In the
forest, the conditions are different. Here, the tree-enemies have to
be battled with, just as in the open, and in addition, instead of
there being only a few trees on a plot of ground, there are
thousands growing on the same area, all demanding the same things
out of a limited supply. The struggle for existence, therefore,
becomes keen, many falling behind and but few surviving.
This struggle begins with the seed. At first there are thousands of
seeds cast upon a given area by the neighboring trees or by the
birds and the winds. Of these, only a few germinate; animals feed on
some of them, frost nips some and excessive moisture and unfavorable
soil conditions prevent others from starting. The few successful
ones soon sprout into a number of young trees that grow thriftily
until their crowns begin to meet. When the trees have thus met, the
struggle is at its height. The side branches encroach upon each
other (Fig. 123), shut out the light without which the branches
cannot live, and finally kill each other off. The upper branches vie
with one another for light, grow unusually fast, and the trees
increase in height with special rapidity. This is nature's method of
producing clear, straight trunks which are so desirable for poles
and large timber. In this struggle for dominance, some survive and
tower above the others, but many become stunted and fail to grow,
while the majority become entirely overtopped and succumb in the
struggle; see Fig. 139.
But in this strife there is also mutual aid. Each tree helps to
protect its neighbors against the danger of being uprooted by the
wind, and against the sun, which is liable to dry up the rich soil
around the roots. This soil is different from the soil on the open
lawn. It consists of an accumulation of decayed leaves mixed with
inorganic matter, forming, together, a rich composition known as
_humus_. The trees also aid each other in forming a close canopy
that prevents the rapid evaporation of water from the ground.
The intensity of these conditions will vary a great deal with the
composition of the forest and the nature and habits of the
individual trees. By composition, or type of forest, is meant the
proportion in which the various species of trees are grouped; i.e.,
whether a certain section of woodland is composed of one species or
of a mixture of species. By habit is meant the requirements of the
trees for light, water and food.
Some trees will grow in deep shade while others will demand the
open. In the matter of water and food, the individual requirements
of different trees are equally marked.
The natural rapidity of growth of different species is also
important, and one caring for a forest must know this rate of
growth, not only as to the individual species, but also with respect
to the forest as a whole. If he knows how fast the trees in a
forest grow, both in height and diameter, he will know how much
wood, in cubic feet, the forest produces in a year, and he can then
determine how much he may cut without decreasing the capital stock.
The rate of growth is determined in this way: A tree is cut and the
rings on the cross-section surface are counted and measured; see
Fig. 124. Each ring represents one year's growth. The total number
of rings will show the age of the tree. By a study of the rings of
the various species of trees on a given plot, the rate of growth of
each species in that location can be ascertained and, by knowing the
approximate number of trees of each species on the forest area, the
rate of growth of the whole forest for any given year can be
determined.
Forests prevent soil erosion and floods: Forests help to regulate the
flow of streams and prevent floods. Most streams are bordered by
vast tracts of forest growths. The rain that falls on these forest
areas is absorbed and held by the forest soil, which is permeated
with decayed leaves, decayed wood and root fibers. The forest floor
is, moreover, covered with a heavy undergrowth and thus behaves like
a sponge, absorbing the water that falls upon it and then permitting
it to ooze out gradually to the valleys and rivers below. A forest
soil will retain one-half of its own quantity of water; i.e., for
every foot in depth of soil there can be six inches of water and,
when thus saturated, the soil will act as a vast, underground
reservoir from which the springs and streams are supplied (Fig.
125). Cut the forest down and the land becomes such a desert as is
shown in Fig. 126. The soil, leaves, branches and fallen trees dry
to dust, are carried off by the wind and, with the fall of rain, the
soil begins to wash away and gullies, such as are shown in Fig. 127,
are formed. Streams generally have their origins in mountain slopes
and there, too, the forests, impeding the sudden run off of the
water which is not immediately absorbed, prevent soil erosion.
Where the soil is allowed to wash off, frequent floods are
inevitable. Rain which falls on bare slopes is not caught by the
crowns of trees nor held by the forest floor. It does not sink into
the ground as readily as in the forest. The result is that a great
deal of water reaches the streams in a short time and thus hastens
floods. At other periods the streams are low because the water which
would have fed them for months has run off in a few days. The farms
are the first to suffer from the drouths that follow and, during the
period of floods, whole cities are often inundated. Fig. 128 shows
such a scene. The history of Forestry is full of horrible incidents
of the loss of life and property from floods which are directly
traceable to the destruction of the local forests and, on the other
hand, there are many cases on record where flood conditions have
been entirely obviated by the planting of forests. France and
Germany have suffered from inundations resulting from forest
devastation and, more than a hundred years ago, both of these
countries took steps to reforest their mountain slopes, and thereby
to prevent many horrible disasters.
How forests are established: New forests may be started from seed or
from shoots, or suckers. If from seed, the process may be carried on
in one of three ways:
First, by sowing the seed directly on the land.
Second, by first raising young trees in nurseries and later setting
them out in their permanent locations in the forest. This method is
applicable where quick results are desired, where the area is not
too large, or in treeless regions and large open gaps where there
is little chance for new trees to spring up from seed furnished by
the neighboring trees. It is a method extensively practiced abroad
where some of the finest forests are the result. The U.S.
government, as well as many of the States, maintain forest-tree
nurseries where millions of little trees are grown from seed and
planted out on the National and State forests. Fig. 129 shows men
engaged in this work. The fundamental principles of starting and
maintaining a nursery have already been referred to in the chapter
on "What Trees to Plant and How."
The third method of establishing a forest from seed is by cutting
the trees in the existing forest so that the seed falling from the
remaining trees will, with the addition of light and space, readily
take root and fill in the gaps with a vigorous growth of trees,
without artificial seeding or planting. This gives rise to several
methods of cutting or harvesting forests for the purpose of
encouraging natural reproduction. The cutting may extend to single
trees over the whole area or over only a part of the whole area.
Where the cutting is confined to single trees, the system is known
as the "Selection System," because the trees are selected
individually, with a view to retaining the best and most vigorous
stock and removing the overcrowding specimens and those that are
fully mature or infested with disease or insects.
Fig. 130 is a diagrammatic illustration of the operation of this
system. In another system the cutting is done in groups, or in
strips, and the number of areas of the groups or strips is extended
from time to time until the whole forest is cleared. This system is
illustrated in Fig. 131. Still another method consists in
encouraging trees which will thrive in the shade, such as the beech,
spruce and hemlock, to grow under light-demanding trees like the
pine. This system presents a "two-storied" forest and is known by
that name. The under story often has to be established by planting.
In the system of reproducing forests from shoots or suckers, all
trees of a certain species on a given area are cut off and the old
stumps and roots are depended upon to produce a new set of sprouts,
the strongest of which will later develop into trees. The coniferous
trees do not lend themselves at all to this system of treatment,
and, among the broadleaf trees, the species vary in their ability to
sprout. Some, like the chestnut and poplar, sprout profusely; others
sprout very little.
How forests are protected: Forestry also tries to protect the forests
from many destructive agencies. Wasteful lumbering and fire are the
worst enemies of the forest. Fungi, insects, grazing, wind, snow and
floods are the other enemies.
By wasteful lumbering is meant that the forest is cut with no regard
for the future and with considerable waste in the utilization of the
product. Conservative lumbering, which is the term used by foresters
to designate the opposite of wasteful lumbering, will be described
more fully later in this study.
Protection from fire is no less important than protection from
wasteful lumbering. Forest fires are very common in this country and
cause incalculable destruction to life and property; see Fig. 132.
From ten to twelve million acres of forest-land are burnt over
annually and the timber destroyed is estimated at fifty millions of
dollars. The history of Forestry abounds in tales of destructive
fires, where thousands of persons have been killed or left
destitute, whole towns wiped out, and millions of dollars in
property destroyed. In most cases, these uncontrollable fires
started from small conflagrations that could readily, with proper
fire-patrol, have been put out.
There are various ways of fighting fires, depending on the character
of the fire,--whether it is a surface fire, burning along the
surface layer of dry leaves and small ground vegetation, a ground
fire, burning below the surface, through the layer of soil and
vegetable matter that generally lines the forest floor, or a top
fire, burning high up in the trees.
When the fire runs along the surface only, the injury extends to the
butts of the trees and to the young seedlings. Such fires can be put
out by throwing dirt or sand over the fire, by beating it, and,
sometimes, by merely raking the leaves away.
Ground fires destroy the vegetable mold which the trees need for
their sustenance. They progress slowly and kill or weaken the roots
of the trees.
Top fires, Fig. 133, are the most dangerous, destroying everything
in their way. They generally develop from surface fires, though
sometimes they are started by lightning. They are more common in
coniferous forests, because the leaves of hardwoods do not burn so
readily. Checking the progress of a top fire is a difficult matter.
Some fires will travel as rapidly as five miles an hour, and the
heat is terrific. The only salvation for the forest lies, in many
cases, in a sudden downpour of rain, a change of wind, or some
barrier which the fire cannot pass. A barrier of this kind is often
made by starting another fire some distance ahead of the principal
one, so that when the two fires meet, they will die out for want of
fuel. In well-kept forests, strips or lanes, free from inflammable
material, are often purposely made through the forest area to
furnish protection against top fires. Carefully managed forests are
also patrolled during the dry season so that fires may be detected
and attacked in their first stages. Look-out stations, watch-towers,
telephone-connections and signal stations are other means frequently
resorted to for fire protection and control. Notices warning campers
and trespassers against starting fires are commonly posted in such
forests. (Fig. 143.)
The grazing of sheep, goats and cattle in the forest is another
important source of injury to which foresters must give attention.
In the West this is quite a problem, for, when many thousands of
these animals pass through a forest (Fig. 134), there is often very
little young growth left and the future reproduction of the forest
is severely retarded. Grazing on our National Forests is regulated
by the Government.
As a means of protection against insects and fungi, all trees
infested are removed as soon as observed and in advance of all
others, whenever a lumbering operation is undertaken.
How forests are harvested: Forestry and forest preservation require that
a forest should be cut and not merely held untouched. But it also
demands that the cutting shall be done on scientific principles, and
that only as much timber shall be removed in a given time as the
forest can produce in a corresponding period. After the cutting, the
forest must be left in a condition to produce another crop of
timber within a reasonable time: see Fig. 122. These fundamental
requirements represent the difference between conservative lumbering
and ordinary lumbering. Besides insuring a future supply of timber,
conservative lumbering, or lumbering on forestry principles, also
tends to preserve the forest floor and the young trees growing on
it, and to prevent injury to the remaining trees through fire,
insects and disease. It provides for a working plan by which the
kind, number and location of the trees to be cut are specified, the
height of the stumps is stipulated and the utilization of the wood
and by-products is regulated.
Conservative lumbering provides that the trees shall be cut as near
to the ground as possible and that they shall be felled with the
least damage to the young trees growing near by. The branches of the
trees, after they have been felled, must be cut and piled in heaps,
as shown in Fig. 122, to prevent fire. When the trunks, sawed into
logs, are dragged through the woods, care is taken not to break down
the young trees or to injure the bark of standing trees. Waste in
the process of manufacture is provided against, uses are found for
the material ordinarily rejected, and the best methods of handling
and drying lumber are employed. Fig. 135 shows a typical sawmill
capable of providing lumber in large quantities.
In the utilization of the by-products of the forest, such as
turpentine and resin, Forestry has devised numerous methods for
harvesting the crops with greater economy and with least waste and
injury to the trees from which the by-products are obtained. Fig.
136 illustrates an improved method by which crude turpentine is
obtained.
Forestry here and abroad: Forestry is practiced in every civilized
country except China and Turkey. In Germany, Forestry has attained,
through a long series of years, a remarkable state of scientific
thoroughness and has greatly increased the annual output of the
forests of that country.
In France, Switzerland, Austria, Hungary, Norway, Sweden, Russia
and Denmark, Forestry is also practiced on scientific principles and
the government in each of these countries holds large tracts of
forests in reserve. In British India one finds a highly efficient
Forest Service and in Japan Forestry is receiving considerable
attention.
In the United States, the forest areas are controlled by private
interests, by the Government and by the States. On privately owned
forests, Forestry is practiced only in isolated cases. The States
are taking hold of the problem very actively and in many of them we
now find special Forestry Commissions authorized to care for vast
areas of forest land reserved for State control. These Commissions
employ technically trained foresters who not only protect the State
forests, but also plant new areas, encourage forest planting on
private lands and disseminate forestry information among the
citizens. New York State has such a Commission that cares for more
than a million acres of forest land located in the northern part of
the State. Many other States are equally progressive.
The United States Government is the most active factor in the
preservation of our forests. The Government to-day owns over two
hundred million acres of forest land, set aside as National Forests.
There are one hundred and fifty individual reserves, distributed as
shown in Fig. 137 and cared for by the Forest Service, a bureau in
the Department of Agriculture. Each of the forests is in charge of a
supervisor. He has with him a professional forester and a body of
men who patrol the tract against fire and the illegal cutting of
timber. Some of the men are engaged in planting trees on the open
areas and others in studying the important forest problems of the
region. Fig. 138.
Where cutting is to be done on a National Forest, the conditions are
investigated by a technically trained forester and the cutting is
regulated according to his findings. Special attention is given to
discovering new uses for species of trees which have hitherto been
considered valueless, and the demand upon certain rare species is
lessened by introducing more common woods which are suitable for use
in their place.
Aside from the perpetuation of the national forests, the U.S.
Forest Service also undertakes such tree studies as lie beyond the
power or means of private individuals. It thus stands ready to
cooperate with all who need assistance.
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Tree Studies
How To Identify Trees
Group I The Pines
The White Pine (pinus Strobus)
The Pitch Pine (pinus Rigida)
The Scotch Pine (pinus Sylvestris)
Group Ii The Spruce And Hemlock
The Norway Spruce (picea Excelsa)
Hemlock (tsuga Canadensis)
Group Iii The Red Cedar And Arbor-vitae
Red Cedar (juniperus Virginiana)
Arbor-vitae; Northern White Cedar (thuja Occidentalis)
Group Iv The Larch And Cypress
The European Larch (larix Europaea)
Bald Cypress (taxodium Distichum)
Group V The Horsechestnut, Ash And Maple
The Horsechestnut
The White Ash (fraxinus Americana)
Sugar Maple (acer Saccharum)
Silver Maple (acer Saccharinum)
Red Maple (acer Rubrum)
Norway Maple (acer Platanoides)
Box Elder (acer Negundo)
Group Vi Trees Told By Their Form: Elm, Poplar, Gingko And Willow
American Elm (ulmus Americana)
Lombardy Or Italian Poplar (populus Nigra, Var Italica)
Gingko Or Maidenhair Tree (gingko Biloba)
Weeping Willow (salix Babylonica)
Group Vii Trees Told By Their Bark Or Trunk: Sycamore, Birch, Beech,
Blue Beech, Ironwood, And Hackberry
The Sycamore Or Plane Tree (platanus Occidentalis)
Gray Or White Birch (betula Populifolia)
American Beech (fagus Americana)
Blue Beech Or Hornbeam (carpinus Caroliniana)
Hackberry (celtis Occidentalis)
Group Viii The Oaks And Chestnut
White Oak (quercus Alba)
Black Oak (quercus Velutina)
Red Oak (quercus Rubra)
Pin Oak (quercus Palustris)
Chestnut (castanea Dentata)
Group Ix The Hickories, Walnut And Butternut
Shagbark Hickory (hicoria Ovata)
Mockernut Hickory (hicoria Alba)
Black Walnut (juglans Nigra)
Group X Tulip Tree, Sweet Gum, Linden, Magnolia, Locust, Catalpa,
Dogwood, Mulberry And Osage Orange
Tulip Tree (liriodendron Tulipifera)
Sweet Gum (liquidambar Styraciflua)
American Linden (tilia Americana)
The Magnolias
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Informational