They Work: Nature's Tinderbox
a metal box for holding readily combustible material,
such as dry twigs, used to kindle fires. Our pioneer forefathers
would protect their tinderboxes from the damp and wet,
literally with their lives.
One sunny afternoon, a father
and his daughter were hiking in a forest. When they finished
sharing a bottle of lemonade, they stood up and forgot the bottle
lying on the ground. The bottle lay there. Leaves and pine needles
fell on it, soil dirtied it, snow covered it, rain washed it
off. Eventually, only a small part of the bottle glistened above
Several years later, the summer
proved to be particularly hot and dry. Leaves crackled, needles
crunched, and twigs snapped when hikers stepped on them; even
the leaves on the trees were turning brown. For a month there
was no rain, and the humidity was particularly low. The forest
became a tinderbox. A sliver of sunlight pierced the forest
canopy, reached the edge of the bottle, and the glass magnified
the heat of the light onto the pine needles that lay beneath
it. The heat caused the needles to burst into flame. The air
and fuel were so dry, and the debris on the ground so loosely
packed, that the air, smoke, and gases rising out of the flames
spread rapidly. They leapt up to the parched branches and leaves
on the trees, and leap-frogged from one tree to the next. The
brisk wind carried the flames with it. A forest fire had come
Fires are what they
Forest fires spread in three different
ways, depending on where most of the forest's fuel is located.
Surface fires burn the low-lying plants and shrubs (more or
less up to the height of an adult's waist) and the litter and
debris that accumulate on the ground. Crown fires move through
the tops of trees, leaping from treetop to treetop. Crown fires
are sprinters, the fastest spreading and most dramatic of all
forest fires. When winds are strong, they can burn their way
across the tops of forests at speeds of 16 km. per hour or more!
(Note: The world's top sprinters can run over 34 km. per hour.
The world's top marathoners average around 21 km. per hour.)
Ground fires are plodders. They creep beneath the surface litter,
consuming dead and decomposing organic materials in a slow-moving,
unspectacular fashion. They are known to begin in campfires
and burn through the root systems of dead trees, springing up
in many places at once. They are extremely destructive and perhaps
the most difficult to track and bring under control. Of course,
most wildfires are blends of all three types, and they travel
in often unpredictable patterns and directions until the weather
changes or their fuel supply runs out.
What goes around...like
a carousel or wheel of fate.
The forest where the girl and her father
hiked that hot, dry summer was destroyed by the wildfire. People
came to the edge of the forest and looked. The ground was the
color of ash, and the trees were blackened stumps. They saw
no plants, no flowers, no green leaves, no birds, nor did they
slap any pesky mosquitoes. The people looked and shook their
heads, and some even cried. "The forest has died,"
they decided, and they walked away, looking for another place
to enjoy nature.
The people couldn't see the tumult
of life beneath the charred surface. The forest hadn't died.
The soil was still there, and all the burned materials were
making it richer still. Within a month after the fire, grasses
and plants began to poke above the ashes, and birds and other
small animals found food and building materials in the debris.
Seeds sheltered from the fire inside cones or deep in the soil
came to life. The rains returned and watered them. With the
tall trees gone, sunlight was able to reach the ground, giving
life to hundreds of thousands of seedlings that wouldn't have
survived in the deep shadows of the old forest. A variety of
fast-growing, light-hungry tree species and fruit-bearing bushes,
such as whortleberry and huckleberry bushes, luxuriated in the
new conditions; while the slower-growing shade trees common
to the old forest were scarcely to be seen. Over the years,
the seedlings became saplings, young trees grew to the height
of humans. People began to return to the forest. The saplings
grew into tall trees with lush leafy canopies or thick coats
of pine needles. Once again, the ground was in shade. The plants
and trees that preferred shade finally had their turn to grow.
Over the decades, they grew to dominate the forest, for the
light-hungry trees could not tolerate the new conditions. People
who hiked along the shady paths thought of the forest as ancient.
Then, one sunny, spring afternoon,
a father and his daughter were hiking in the forest. When they
finished sharing a bottle of lemonade, they left the bottle
on the ground, beside the rock that had warmed them as they
- Describe the 3 different ways in which forest fires spread.
- A forest fire has just occurred. Draw a circular diagram to describe what will likely happen before
the next fire.
- What conditions might be present in a forest immediately before a fire?