More ThanTrees (1976)


Uploaded by moconservation on 14.03.2012

Transcript:
More Than Trees (1976)
Narrator: When the European first became acquainted with the vast forest of eastern North America,
it was unlike anything he had ever beheld.
The great American deciduous forest is unique.
The forests of Europe are much poorer in the number of species of tree.
The seemingly endless forest was both friend and foe to the colonist.
It provided shelter and materials for the things he needed,
but it also harbored the unknown.
To most, it was something to be conquered and done away with.
Even today, the descendants of those pioneers
still are largely ignorant of the complex wonders that are the American forest.
(owl hooting)
Basically, a forest is trees.
Even in winter, it is the trees that dominate the landscape
slumbering under its blanket of snow.
But what seems a lifeless woodland is deceptive.
Beneath the snow, below the frost line, the earth throbs with living organisms.
These myriad life forms are hidden now.
Above the ground, others of the forest community are abroad.
The pileated woodpecker is a splash of color.
And tiny chickadees are very much a part of the winter forest.
(crow cawing)
The raucous crow tells the forest world that a red fox is abroad and on the prowl.
(crow cawing)
Thus a forest is more than trees.
It is a dynamic community of living things, both plant and animal, all interwoven.
In winter, the trees are dormant.
Their sturdy trunks sheathed in bark.
Corky cells of bark filled with air insulate the tender tissues beneath.
Tough scales protect leaf buds from water loss.
Inside, a concentrated substance keeps them from freezing,
nature's own antifreeze.
Though most plants are dormant, one unique group is active now.
Lichens grow on the soil, rocks, and trunks of trees
and add color wherever they live.
Actually a lichen is a partnership of two kinds of plants:
fungi and algae.
The fungus partner furnishes support and provides water.
The other partner manufacturers the food supply and gives color to the plant.
The bizarre forms and colors of the lichens form a miniature wonderland in the winter woods.
Many animals of the forest are dormant at this time too,
like this gray tree frog hibernating beneath the insulating blanket of snow and plant material on the forest floor.
Before frost, this box turtle dug down into the zone that never freezes.
Safe against the winter's cold in a decaying log, a tightly coiled millipede sleeps away the winter.
An anti-freezing agent in body fluids protects the dormant stage of a butterfly.
Overwintering egg masses of tent caterpillars and assassin bugs await the touch of spring.
They are a source of nourishment for winter birds like the nuthatch.
Winter birds are both resident and visitors from the north.
They glean the forest of insects, searching them out from old hornet nests,
under bark, and inside dead trees.
They are a check on insect life in the forest community.
Seed-eating birds forage throughout the forest, too.
Seed-eating birds forage throughout the forest, too.
A white-tailed buck in an ancient rite slashes a limber cedar and leaves his mark.
Great or small, plant or animal, all interact to form the forest community.
A flash of crimson on an icy branch doesn't make a spring.
But when the icicles begin to drip, and little freshes begin to run,
and the cardinal adds his song,
(cardinal song)
then spring is surely on its way.
As the sun moves northward on its annual trek, it gradually warms the soil and moderates the temperature.
Of all the environmental factors that influence the forest,
the seasonal lengthening and shortening of day and night are the most constant.
Some plants that have remained green all winter forecast spring by brightening their leaves.
The velvety mosses that add color during winter's bleakness
begin to push forth long stalks, each with its tiny capsules of spores to continue the lifecycle.
The mourning cloaked butterfly wintered as an adult,
frequently leaving sheltered spots to fly about on tattered wings.
Now there is a quickening deep within the soil too.
In a hidden environment, more stable than that above the ground,
chemical changes are occurring.
Stored foods in the thick supporting tree roots are being changed into usable form.
Out from smaller roots, microscopic hairs grow
and penetrate the soil, absorbing water and minerals dissolved in it.
This liquid passes into the tree and upward,
defying gravity through specialized water-carrying tubes just under the bark.
It goes up the trunk and to the outermost branches.
Here, buds receive the liquid nourishment and begin to swell.
The sheath of scales that protected the buds in winter is forced open,
releasing embryonic leaves or blossoms whose magic hour has come.
As sunlight begins to bathe the new leaves,
a growth hormone is formed that stimulates the growth of leaf, flower, and root.
Spring, now, is literally busting out all over.
In some trees, the first buds to open form leaves.
Many new leaves show red pigments at first,
giving a pink blush to the spring forest.
In other trees, flowers appear before the leaves, like this redbud.
The tiny flowers of oaks depend upon the capricious winds of spring to carry their pollen.
Hickories, too, rely upon the wind.
More showy flowers are usually pollinated by insects often highly specialized for their friendly role.
The forest floor is now receiving its maximum sunlight.
Fueled by food stored in their roots from the previous year's growth, green shoots and blossoms appear.
In the brief span of sunlight allowed to them in spring before the canopy of leaves closes above,
many of these plants manufacture their whole year's supply of food,
produce their flowers, and form seeds and buds for next year's growth.
From root-like threads deep within the carpet of leaves,
large fungi push upward to gain room for their spore-producing bodies.
Unlike green, leafy plants of the forest, fungi do not manufacture their own food,
but rely mostly upon decaying plant matter as their source of nourishment.
The sun, which stimulated the growth of plants, also controls the life cycles of forest animals.
The roughed grouse, a connoisseur of fallen logs in woodland thickets,
The roughed grouse, a connoisseur of fallen logs in woodland thickets,
chose this particular log for his courting display, for reasons only a grouse knows.
(grouse drumming noise)
(turkey gobbling)
Narrator: Against the windy March sunset, the peeping song of the male woodcock
announces his arrival from the southand his choice of a mating territory along the woodland edge.
Now other migrants move north, each finding a place in the forest.
Grackles scour the forest floor, searching out insects and seeds hidden in the leaf litter.
A spicebush butterfly emerges from its wintertime chrysalis form.
Overwintering assassin bug eggs hatch and release a hungry brood that will prey on other forest insects.
In a forest glade, drainage water has formed a temporary pool.
Here the spring peeper, a tiny tree frog, comes to sing and breed.
A tiger salamander crawls over land through damp mosses and leaves to the forest pool where she will mate and lay her eggs.
Another woodland creature awakens to the spring, a gray tree frog.
Remarkably camouflaged, few see this tiny sprite.
He too will journey to the woodland pool.
The sun's warmth wakes the land snail, which has spent the winter below the frost line.
Earthworms move into upper layers of the forest floor in spring.
They extract nutrients from the soil they eat and pass the residue through their bodies,
conditioning the soil for bacterial action.
The activities of all burrowing creatures have a profound effect upon the forest soil.
They aerate it, mix its elements, and affect drainage,
all of which stimulate root and plant growth.
(turkey gobbling)
When the green mantel of spring finally cloaks the forest,
the orderly series of events in which both plants and animals have roles already is well underway.
New buds and leaves supplement the stored foods that have carried squirrels through the winter
and are vital to this nursing female.
Elms, among the first to leaf, provide an important spring food for deer.
A puffball fungus is accidentally brushed by the deer's hoof, releasing a cloud of spores.
Spring in the forest progresses steadily, drawn forward with the sunlight's increase.
Each day is longer, the air warmer, and the trees greener.
Once underway, growth is rapid.
From the time buds burst forth, it takes only seven to ten days for leaves to reach their full size.
It is in these new leaves that the most important event in the forest takes place:
the drafting of solar energy in the manufacture of sugar.
The tiny network of veins transports the sugar from the leaves to the rest of the plant.
This sugar is the basic substance in the forest upon which all life depends.
It is used for growth of the tree and for its reproduction.
During the growing season the green plants of the forest not only make enough food for their own needs during the entire year,
but also provide food for all other forms of life in the community.
Summer comes to the forest when the sun reaches its northernmost point.
Utilizing the long daylight to the fullest, the tree's green energy produces new growth,
buds for next year's leaves and flowers, and fruit containing seeds for new generations.
and fruit containing seeds for new generations.
In the forest there are layers of habitat, each with its own plants and animals.
The leafy crown of the tallest trees is the canopy.
Here, sunlight is most intense and temperatures fluctuate widely.
When the sunlight becomes too intense, the leaves turn sideways to the direct rays.
Specific animals live in the canopy and flying insects are abundant.
The crested flycatcher is typical of this niche.
The blue-gray gnatcatcher is at home in the more open parts of the canopy, feeding on the insects of this zone.
Under the sky-sweeping canopy is the mid-layer, or understory.
There is still adequate sunlight for photosynthesis here.
Some tree species are waiting for an opening in the canopy.
Others have evolved to live in the shade of the canopy,
like dogwood and redbud trees.
Here, too, certain birds find conditions to their liking.
Beneath the understory is the forest floor.
Dwarfed by the towering giants above them,
shrubs and herbs grow close to or on the ground.
Flecks of sunlight reach the forest floor as the sun passes or as the wind blows the canopy.
Enough light reaches these shade-tolerant plants for them to complete their lifecycle, too.
The shade-dappled forest floor has its own animals.
In a patch of mayapples, a doe hides her newborn fawn.
A Kentucky warbler is typical of birdlife in the low undergrowth.
And a three-toed box turtle is one of the many creatures that prefers the forest floor.
Bright, sunlit patches are sought by a lizard,
which forages for insects likewise attracted to the warm, sunny spots.
The layered effect of the forest continues on beneath the ground's surface.
The forest carpet is an accumulation of leaves and other debris through which very little sunlight filters.
This material is broken down by the life activities of millions of small creatures such as insect larvae,
millipedes, and larger forms like shrews and white-footed mice.
Even earthworms play their part.
Rain and snow water trickle through their tunnels, aiding in the breakdown.
In the next, deeper layer, much of the chemical breakdown of the forest takes place.
Here in the eerie darkness of a surrealistic world,
fungi digest the cellulose leaf parts and woody material for their food.
Some fungi help tree roots take in water and minerals and supply essential nutrients for tree growth.
Tiny threadworms, one of the most abundant of soil animals,
hasten the decomposition process.
Imperceptibly deeper live the final agents of decay, bacteria.
Their life processes free important chemical elements into the soil and air
Their life processes free important chemical elements into the soil and air
where they may again be captured by plants,
thus completing the recycling of nutrients in the forest.
The drama of life and death in a forest is revealed as a tree succumbs to old age or disease.
For a time, the snag becomes an apartment house for the community.
Woodpeckers search for burrowing insects and chisel out nest cavities.
Later tenants are the crested flycatcher and the bluebird.
Such holes may become homes for gray squirrels, and flying squirrels,
or even the broad-headed skink.
But ultimately the tree stub returns to earth.
Rays of sunlight stream into the new opening created by the death of the tree.
This will change conditions dramatically on the forest floor below.
It is in these openings that the forest regenerates itself.
Germinating seedlings bathe in the sunlight, and plants of all sorts begin the competition for their place in the sun.
Ultimately, only a few will survive to become the forest patriarchs.
Such openings also have profound effects on animal life in the forest.
Deer and turkeys are attracted to the feast provided by this variety of plant life.
Once on the ground, the mechanical breakdown and decay of the log speeds up.
In this process, the energy from sunlight stored in the tree trunk years before
now provides food for many forms of life.
Ants excavate the wood and dispose of tiny wood particles outside their tunnel system.
Other insects create a labyrinth of galleries all aiding in decay.
Termites literally eat their way through the log, receiving nourishment from the cellulose.
The log supports a host of fungi, which secrete enzymes that hasten decomposition.
Fungi were already at work before the tree fell,
but the moist conditions near the ground are especially favorable for their activity.
Rainwater seeps into the rotting log, favoring different fungi and insects like this fly larva.
Various soil animals come up from the leaf carpet to feed on decaying matter and find homes in the old log.
Even the old stump has its cycle of decay.
Rainwater may collect in the stump and harbor a community of tiny plants and animals.
These fly larvae, called rat-tailed maggots, snorkel air through breathing tubes.
As a result of all of these activities,
the log gradually passes into the ground for other agents of decay to work on.
From its elements will rise other trees.
Summertime in the forest is insect time.
The summer sun, and its energy stored in the leaves,
provide a bountiful pasture for a host of insects and those who prey on them.
By midsummer, most of spring's fresh leaves are scarred by insect attack.
Most caterpillars are specialists.
Leaf rollers make leaves into all-weather shelters.
Fall webworm caterpillars build their own tent city.
Usually a forest and its insect population live in some sort of harmony,
but sometimes insects, like these walking sticks,
become too abundant and damage some parts of the tree.
Certain trees, like oaks, are selected by variable oak leaf caterpillars for their host.
Malformations called galls may form on leaves or stems
where certain wasps, flies, aphids, and mites lay their eggs.
Galls are incubators where young insects develop.
Long before acorns mature and drop,
some have been selected by the probing acorn weevil as a site for her eggs and developing young.
The effects of the weevil's activity will not become apparent until autumn.
As the cycle of the seasons continues,
shortening days indicate the sun's waning influence.
Both days and nights are cooler, the leaves no longer make sugar, summer is over.
When daylight shortens to a precise time,
a growth-retarding hormone forms in the leaves and travels to the base of each leaf stem.
It causes a corky layer to develop, gradually shutting off the water supply to the leaf.
Without water, the green color of the leaves disappears
and yellow pigments that were masked all summer are now visible.
Red pigments are renewed during warm days and cool nights.
Fall color depends on a number of different factors,
including the kind of tree, amount of moisture in the soil, and when frost first comes.
Fall is an American term
because nowhere else are deciduous forests extensive enough to display the phenomenon so grandly.
The leaf stem separates from the tree and the leaf falls.
The leaves accumulate on the forest floor, forming an insulating blanket for the roots.
Millions of fruits and their seeds are produced, but few develop into mature plants.
Most are consumed by animals in their struggle to survive the winter.
In the deciduous forest, the most important fruit is the acorn crop.
A single oak tree can produce as many as five thousand acorns a year, but production varies annually.
White oak acorns sprout as soon as they drop,
but some fail to do so because of the larva of the acorn weevil growing inside.
In years of abundance, acorns are the staple food of many forest dwelling creatures.
In autumn and winter,
a large part of the diet of wild turkeys and deer may consist of acorns.
Squirrels glean the woods for nuts to eat and store.
Many of the stored nuts will germinate to perpetuate the forest.
Only a few are eaten.
(owl hooting)
Thus the forest is many things,
each with its annual cycle depending ultimately on the sun.
Everything that lives in a forest or uses it has a point of view.
Only man has the capability of seeing and understanding the forest in its entirety,
though few of us do.
Most of us get so involved in one aspect that we cannot see the forest for the trees.
Like the red-tailed hawk who sees it as a source of food,
or the hunter who sees it mainly as a place for sport,
or the lumber man who measures it in terms of board feet
There are those who are interested in certain details,
ike the biologist or the biologist-to-be.
And there are those who seek the forest for beauty or pleasure.
But whatever our needs or desires, to use the forest intelligently,
we must learn to understand and appreciate that a forest is more than trees.