Fire in the Forest
Constantly guarding your northeastern forests are sharp eyes looking for smoke.
No, not this.
Permanent smoke is what the lookout calls signs of residence and industry.
He knows that this smoke comes from a paper mill.
But wait, has he found a new smoke?
Does that faint column mean another demon is loose?
White colored smoke generally comes from a grass fire but there’s a slope of pines
in that area.
Man fights time, whenever he fights fire.
It’s a sudden and spectacular destroyer, which every year in the United States covers
a forest area equal to the size of New York State.
Each spring and fall, conditions are right for this menace.
Summer fires are also tough to handle.
In truth, the best forest fires are those that never happen.
As for those that do, it’s everyone’s business to know your enemy and understand
the conditions that repeatedly put this demon in your woodland and once there, how it behaves.
From the lookout, the smoke appears bluish gray as it billows up in a definite column.
When seen close up, the smoke spreads and turns a tell-tale dirty brown color.
Fire in the forests is a vital phrase for an ancient enemy, against which man’s been
fighting a winning battle only since the turn of the century.
One of the first lessons learned is that the time between fire report and arrival at fire
must be short.
Fire control is easiest in the early stages.
The start of organized fire control is in the memory of many men, some of whom are still
fighting fires.
The fire boss issues tools necessary to fight each particular fire.
Correct decision take training, judgment and experience.
Each fire presents problems which demand a different order of attack.
Every year, there’s some gain in the speed and efficiency of detecting and reporting
fires and the work of controlling them.
But the job keeps getting bigger.
More people are using the woods, additional forests are coming under protection and fire
detecting is becoming more accurate.
Because of these changes the total number of fires reported in the northeastern states
has been increasing.
However, the general trend is toward lower losses in burned over area.
Records of individual fire reports are mainly to help up learn about fire’s behavior in
the forests, each burn is different in its rate of spread and in its severity.
For instance, this is now a forest of grey skeletons and black ashes.
But the damage doesn’t stop here; a dead forest carpeted with its own ashes does a
poor job in retaining rainfall.
This is the first step towards land erosion, and watershed damage.
The factors which govern fire behavior are always the same.
For the tenderfoot who is learning that sometimes the factors are wrong for even matches to
burn.
Too bad, he doesn’t get his second last badge.
Adults too, should know more about factors which govern fire behavior.
The big lesson is that the very same factors which make forest fires work in many different
combinations and with varying force.
Any fire warden could’ve told the campers this day was dangerous for building a campfire.
Foresters know when fires are likely to happen and how bad the burn might be.
They understand the three main conditions which control fire behavior-fuel, weather
and slope.
Let’s look into these various types of fuel.
For instance, green fuel.
This sample happens to be maple in early summer.
Green grass has the same fire characteristics.
A fire source is lighted.
That isn’t smoke, its steam.
The fire has to dry out the water before the fuel can burn.
These green fuels are not dangerous in summer, except when it is very dry and windy, or where
large fires are underway.
Next type, slow burning-or heavy fuels.
These are generally bulky logs, stumps or snags.
Because this is a heavy fuel, little burning surface is exposed to the air.
Heavy fuel dries out slowly and is slow to catch fire and burn.
Under the right conditions, given a chance to dry out, heavy fuels make hot and dangerous
fires, which are difficult to suppress.
Flashy fuel types such as dry grass, dry leaves and twigs blaze on contact with fire, burning
easily and quickly, because they are thin, and air can get all around them.
Affecting the burning of all types are, fuel arrangement and continuity.
For the speed at which fire progresses depends on the pattern and the fuel distribution,
fuel quantity- where a fire may burn fast if it can run from one piece of fuel to the
next, or slow where fuel may be patchy and broken up by roads, bare earth, or rock.
Another factor affecting burning is the season of the year and its relation to vegetation
growth in the forest.
In winter, vegetation is cured.
Spring is a transition period, growth begins.
Vegetations is green and reaches full growth in summer.
Fall is a transition period.
Leaves dry and drop to the ground, fire will spread.
Fuel moisture is still another factor which changes as the seasons follow each other through
the year.
Moisture begins to build up in the fuel, during the spring transition period and reaches its
peak in summer.
The fall transition period reduces moisture by drying and curing fuel.
The second main condition which affects the behavior of forest fires is weather.
It takes about five minutes for a tower ban, guard or weather observer to read his instruments
and record the observations.
His first concern is to determine the fuel moisture content, which changes as rapidly
as the weather flocculates.
This simple measurement brings together the weather factors of humidity, temperature,
and evaporation and shows the changes that are happening.
Temperature differences and evaporation changes are easy to understand.
The part they play in affecting the amount of moisture in the air and consequently in
the fuel should be made clear.
That white cloud blanket in the valley is one hundred percent relative humidity.
Nature’s own backpack pump has wetted down this forest.
No worry about fire now, but wait, the sun does its chores-raising the temperature which
in turn increases evaporation.
When the relative humidity drops, the air dries the fuels and then we do have to worry.
Relative humidity is nothing more than a measure as to how much moisture is in the air compared
to how much it will hold.
When it reaches one hundred percent, dew collects or rain begins to fall, building up the fuel
moisture content.
Fire danger is obviously very low; these conditions made the tenderfoot fail his campfire test.
After sunrise, the day grows hotter and drier.
Relative humidity drops lower and lower, air dries the fuels and fire spreads rapidly.
When the humidity goes below fifty percent, this is nature’s danger signal.
Wind is another aspect of weather.
Wind velocity is the first importance in affecting rate of spread.
If fuels are dry enough to burn, we must know the degree of air movement in the forest.
Is this wind gentle?
Is this moderate?
Is this strong?
Wind cannot be estimate, it must be measured.
If an area where there was no wind started to burn, the fire would spread like a growing
circle.
Blow up some wind, and the fire is fanned to burn faster in a definite direction with
an elliptical shape-blowing flames towards less dangerous or more inflammable fuel.
Change the direction of the wind, and the fire face about, running with the new breeze.
To examine slope-the third condition that affects forest fires, we’ll go to Helderman
State Forest at Elizabethville, Pennsylvania.
Here at the state forest headquarters, the chief forest fire warden has built a model
relieve map of the surrounding area that will demonstrate slope and fire for us.
He calls it a fire control training map and it’s now duplicated in various regions throughout
the country.
Built to the scale of one foot equals one mile, it serves as a practical training device
as well as a demonstration aid.
The table is a composite of all terrain, giving us a bird’s eye view of the natural fire
breaks such a roads, streams, lakes, bare fields and all.
Assume that the material he is spreading is natural fuel.
Actually, it’s only colored wood flour and salt peter.
It’s just like the real thing.
As the fuel burns, notice how the natural fire breaks first slow up or completely stop
the spread of the fire.
Some slopes burn more easily-they face the south where they dry more quickly due to the
sun evaporating all the moisture.
That’s why they make for fast spreading fires-which are tough to fight.
But fire isn’t the same on all slopes.
For instance, uphill slopes normally burn hotter and faster.
Rising hot air creates drafts to fan the fire.
But once the fire goes over the ridge, the downhill slope normally burns more slowly.
It has to burn against the in-drafts of cool air.
Even though this is only a forest fire in miniature, it must be suppressed.
Our chief forest fire warden will use this stylist scaled to simulate a ten man fire
crew building a fireline.
To fight any fire- big or small, first stop it from spreading.
Starve the fire by cutting off its fuel supply.
Second, put it out.
Put the fire dead out.
Cut off the air supply.
Put earth on the fire.
Mix live ashes with mineral soil.
Vary it, or lower the heat to cool down the fire with water under pressure.
Time of day affects the basic conditions that make fires.
It increases the fire hazards of the fuel, the weather and the slope.
With the dawn, the sun warms the atmosphere and the earth.
Relative humidity falls.
Around ten a.m., moisture free air begins to circulate and dry the fuels.
It becomes windier and drier, increasing the hazards of warm, dry fuels as the day goes
on.
Around 5 p.m., as the sun drops lower, the air grows cooler, the relative humidity rises,
wind velocity falls, and fuels become less dry.
In the old days, the men who watched our forest also knew that fuel, weather and slope-combined
with the factors of moisture, wind, season and time somehow added up to each day’s
burning possibilities.
But fire forecasting hasn’t kept strides with scientific developments such as the Deluc’s
car of the day.
Rather, they operated according to certain unscientific, rough rules of thumb.
These rules were derived from popular experience and were highly useful to men in terrain familiar
to them.
From observations and from working on fires, the old time foresters could estimate peak
periods of danger in a limited area.
For instance, wind velocity was measured by smoke drift and movement of trees.
Opinions of fire danger were based on simple things, on the extent to which a pine needle
would bend without breaking, or the ease with which a hand could crush hardwood leaves.
They were agreed.
This was a fire day.
But was the danger extreme, moderately bad or just average for the season?
In those days, they were never too sure.
Today, the modern forester makes use of the research and development of forest experiment
stations.
In the laboratories, experts work on forest fire research, timber management, soils, tree
and plant disease and pest control.
Much has been accomplished in developing lookout systems and instruments to detect and report
all fires.
One important development was the fire danger meter.
Here all the variables that make up forest fire danger have been reduced to a simple,
circular slide rule.
Which when properly used, registers the burning index of each day.
The meter adds up the ever-changing details.
Fire danger ratings are reliable because of the careful research and experience applied
in the system and the accurate information used in the daily computations.
Several times a day, measurements of fuel moisture are made at each danger station in
the woods.
The moisture sticks are weighed on this scale to give a numerical value to the amount of
moisture in the fuel.
Wind velocity measurements are made by timing the interval between buzzes.
A simple electrical system translates the speed of the twirling cups into a delayed
sound, which is measured by a sweep hand.
Standardized equipment and methods keep constant check on nature’s pulse.
Precipitation is also recorded.
A simple graduated ruler measure the catch of rain.
These measurements combined with season of year and condition of vegetation- form the
basis for rating the day’s fire danger.
The operator of a danger station can determine the type of a fire day quickly, accurately
and without personal bias by using the one hundred point fire danger meter.
This automatically gives the key factors their proper weight.
First he sets the vegetation condition dial on cured, next the season of the year factor
is set at three-since this observation was made in March.
Then, last rain in inches is taken from the daily record.
Same for days since last rain.
Fuel moisture measured seven.
Wind velocity, six.
These factors make the meter register a burning index of fifty- this makes it a class four
day.
The ratings are expressed in numerical classes from one to five- each having definite meeting,
and calling for definite action.
A class four day means very many fires spreading furiously.
The fire station observer wastes no time in reporting to the district office.
The district officer, in turn, notifies the local radio station to broadcast the warning
to the countryside.
Radio announcer: We interrupt our program at this time to make a special news announcement.
The forest fire danger today is high in all southern counties of this state.
Be especially careful with your brush burning, matches and cigarette butts.
Be sure they’re out before discarding.
Report any wildfires to your local forest warden.
We repeat.
The forest fire danger today is high in all southern counties of this state.
Be especially careful with your brush burning.
Report any wildfires to your local forest warden.
The forest fire danger today is high.
Diagnosing fire hazards and broadcasting warnings do not by themselves stop fire from breaking
out in your woodlands.
If only all the people who used the woods cooperated with their state forest fire service,
this would never happen again.
The insurance is simple, protect your forests and they’ll grow forever.