Effect of forest fires on standing hardwood timber.

Historic, archived document

Do not assume content reflects current
scientific knowledge, policies, or practices

Issued March 31, lOio.

U. S. DEPARTMENT OF AGRICULTURE,

FOREST SERVICE— Circular 216.

HENRY S. GRAVES, Forester.

EFFECT OF FOREST FIRES

ON STANDING HARDWOOD

TIMBER.

BY

W. H. LONG,

Forest Pathologist, Bureau of Plant Industry.

WASHINGTON:

GOVERNMENT PRINTING OFFICE.

1913.

EFFECT OF FOREST FIRES ON STANDING HARDWOOD

TIMBER.

The aim of this leaflet is to point out some of the direct and im-
mediate injurious effects of light fires in a forest. Even a light fire
may and does injure in many ways both public and private timber,
and causes an actual money loss which can be measured in dollars and
cents. When the actual damage done by fires is realized, their pre-
vention will be as much the duty of the citizen as it is now his duty to
protect his home from burning.

The most noticeable effects of a fire are the killing of the young^
growth, the destruction of the layer of leaves and mulch on the
ground which protects the soil from washing in times of heavy rains,
and the fire scars left on the trees of all ages and sizes. It is the
object of this leaflet to call attention especially to the damage to mer-
chantable timber evidenced by these fire scars. Though the study
upon which the circular is based was made in the Ozark Mountains
of Arkan-as. the results are applicable to other hardwood region.-.

All settlers and luml^ermen who have worked in the hardwood
timber in the Ozarks know only too well what is meant by pin worms,
bunch worms, flag worms, grub worms, soak, and butt rots, and how
great is the loss of timber due to them. Damage by insects and rot
was found in connection with practically every fire scar on the bases
of the trees. The fire may have occurred 50 or 100 years ago. and all
signs of it l)een hidden by later growth, but during the two or more
years that it took the tree to heal over the scar, worms, and spores
or germs which produce rot in trees, entered at this open wound on
the butt. and. in the case of the rots, have been at work ever since,
gradually desti-oying the timber in the trunk.

Any little pile of leaves and other trash, which winds and water
may have left lodged against the base of a tree, will, when dry and
set on fire, produce sufficient heat to cook and kill the living bark and
sapwood for several square inches on the butt. The injury thus
caused is apparently slight, but in reality the danuige done may con-
tinue during the entire life of the tree, and may finally caUv^e its
death. It is mainly through such small fire scars that the worms and

rots get into trees.

3

70190' — 13

4 EFFECT OF FOREST FIEES OiiT HARDWOOD TIMBER.

The spores, or " seeds," of the tiny fungus plants which cause the
rot fall on the dead spot or fire scar, sprout during damp weather
and grow into the heartwood of the tree. Once in the heartwood, the
little plants use part or all of the wood as food, and thus gradually
destroy the sound timber, producing what is called rot, dote, or soak
in the trunk of the tree. The small fire scar may, and usually does,
lieal over, so that in a few years no evidence of a fire or injury to the
tree can be seen from the outside; but the rot continues to grow for
years, slowly spreading outward, until it reaches the sapwood, and
upward in the tnmk, thus ruining the tree for most commercial pur-
poses. Every time a tree is reached by a fire hot enough to kill a
small area of the bark and sapwood an opportunity is given for more
worms to enter and for another attack by the little plants which
produce rot. Where trees are growing on steep slopes small piles
of trash collect on the upper sides at the base. In such cases even a
light fire, which ordinarily would not be able to injure the tree at all,
burns this pile of trash and a fire scar is formed. On the sides of
Pilot Mountain are dense stands of young oak saplings from 2 to 6
inches in diameter, every one of which has a fire scar on the upper
side of its base, due to the burning of these piles of trash. This
means that a large number of these saplings will grow into trees
having butt rots and wormholes in the trunks. Similar conditions
can be seen on nearly every mountainside in the Ozarks.

Anyone in passing through a stave sale area after all the good
bolts have been removed has noticed the large amount of cull left on
the ground. Sometimes entire trees have not yielded a single bolt.
What was the matter? Worms, rot, or soak had ruined the tree for
staves. Cull butts from 6 to 16 feet in length are not uncommon on
many areas where the timber has been felled. In nearly eveiw case
these butts were left on account of rot. Practically all of this was
caused by fires which injured the bases of the trees.

The loss of good merchantable timber in a stave operation from
rot and worms alone is enormous. Yet it is often said that light
fires do not injure the forest, and some even claim that it is a benefit
to burn the forests annually. On one stave sale area in the Ozarks
76 trees out of every 100 felled had butt rot, and 27 trees in every
100 had wormholes of some kind in them. "^Yhat does this mean?
It means that after going to the expense of felling 100 trees only
24 of them were perfectly sound and suitable for staves. Not only
was there a money loss from the cull of 76 trees, but the expense of ■
felling unsound trees must be considered. For five widely separated
areas in the eastern part of this forest an average of 65 trees in
every 100 had butt rot, and 26 had wormholes sufficient to cull some
of the bolts.

EFFECT OF FOREST FIRES ON HARDWOOD TIMBER.

Most of this loss can be traced directly to the fires so common in
this forest. The area where 76 trees in every 100 were found to have
butt rot has been burned over regularly for years. Over areas where
fires had not been so frequent, the injury from butt rots was corre-
spondingly less. The loss of timber in stave operations from worms
and rots alone will often average one-fourth of the total amount of
material actually used for staves. It is for this very reason that
stave men in buying private timber offer such low prices : they do not
know till the timber is felled and worked up just how much loss
there will be from worms, soak, and rot: they do know, however, that
the loss will be great. The loss from worms and rot caused by forest
fires is not confined to white oak, but extends to red and black oaks
as well. Old fire scars on the butts of these trees are the usual places
where many wood-boring insects enter the tree. On some areas as
many as 33 trees out of every 100 red and black oaks felled had been
injured by grubworms. The usual butt rots of white oak are also
found in the other oaks, and fire scars are the places through which
they enter.

Another way that fires injure standing timber is by burning
through sound bark and sapwood into the hollow butts. Once the
hollowed-out interior of the tree is exposed to the air. the rot which
originally caused the hollow seems to grow up the tree more rapidly,
while other fires that follow gradually widen the hollow and destroy
the bark at the base of the tree until the tree is lolled.

A tree which has an open, hollow butt is much more easily blown
down than one in which the hollow is inclosed by living bark and
sapwood.

We find. then, that forest fires damage standing timber in three
ways : By producing fire scars through which worms enter, by open-
ing a passage through the bark and sapwood for rots to reach the
heartwood, and by weakening trees with hollow butts till they either
burn down, die from fire girdling, or are blown over by strong winds.
Every fire, therefore, only increases the damage by making possible
a new crop of worms in the trees and by giving another chance for
rots to enter through the new fire scars, thus increasing the quantity
of unmerchantable material and decreasing the amount of money
received for the timber.

This deterioration in the standing timber is the direct source of a
tremendous loss to the entire community, for no one will buy worth-
less timber. The timber itself is not only a total loss to the settlei^
and other owners, but by its presence it also increases the cost of lum-
bering and decreases the stumpage value of what timber is merchant-
able. Furthermore it means a loss in wages to the laborer, and a
loss to the State of the 35 per cent of all receipts from the sale of

6

EFFECT OF FOEEST FIRES ON HAEDAVOOD TIMBER.

Government timber appropriated by Congress for the construction
of public roads and for the maintenance of schools within the State.
The conclusion, then, is obvious, that the continued burning of
timbered lands in Arkansas is causing an annual loss of thousands
of dollars — an absolute detriment to the welfare of the State. And
it is equally obvious that this loss can be almost entirely eliminated
b}^ the prevention of all forest fires, whether large or small — a com-
paratively easy matter if all the people will only cooperate in the
work.

ADDITIONAL COPIES o f this publication
-^1- may be procured from the Superintend-
ent OF Documents, Government Printing
Office, Washington, P. C. , at 5 cents per copj

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