Trees And Their Importance (1966)

When the first colonists settled in America over 300 years ago, great forests such as this stretched in an almost unbroken expanse over much of the land, except for prairies, great plains, and deserts. From these forests, the pioneers built homes and furniture, wagons and fences. Since the early settler needed food and shelter, he had no choice but to cut the trees and plow the soil. Many of those who came after exploited the forest resources, using up or laying waste much of the natural growth. Fire, which often followed this kind of logging practice, destroyed the protective covering of humus on the [Applause] ground. Rains eroded what was left of the top soil and wasteland developed. Today the land and all living things suffer because of this negligence. What kind of plant is a tree? And why are trees so important to us? To better understand their structure, how they grow, and the work they do, we will change this picture of an oak into a drawing. The roots not only anchor the plant in the ground, but they also act as the tree's water collecting mechanism. In these time-lapse photographs, you can watch the growth of a root tip and the millions of root hairs behind the tip as they push through the soil. The root hairs absorb water and minerals used for the tree's life and growth. A tree never stops growing until it dies. The stem or trunk of the tree acts like a pipeline. In the sapwood layers under the bark, xylem tissues carry water from the roots to the leaves. Under this microscope, xyllem tubes look like this. Floam tissues which contain tubes with civ-like ends carry food materials dissolved in water downward from the leaves to the growing parts of the tree. Here magnified many times is floam tissue. In a cross-section of the trunk or stem between bark and wood, there is an actively growing area. This appears as a ring of single cells called the cambium. In this drawing, you can see the cambium cells dividing and adding new xyllem tissue which becomes wood and floam tissue which later becomes bark. Watch how the action of the cambium increases the thickness or diameter of the stem. Yet the single ring of living cells remains the same width. Each yearly layer of wood in a stem is usually so distinct that by counting the layers or rings, you can tell the approximate age of the tree. By studying the width of rings, scientists may estimate climatic conditions that existed in the past. In wet seasons, more growth takes place and the tree rings are wider than during dry seasons. The only place we can actually witness growth in a tree is in the buds at the farthest tips of its stems. In this time-lapse picture of a maple seedling, can you see where the stem is growing? It elongates only at the tip. Leaves act like factories and produce food for the tree with the help of sunlight. The energy or power of the sun is used by the green chlorophyll in the leaf to combine carbon dioxide from the air with water from the soil. This very complex chemical process results in sugars, the treere's food. Oxygen is released into the air as a byproduct. This complete process, similar in all green plants, is called photosynthesis. Most of the water that flows from the roots to the leaves is not used in photosynthesis. It evaporates into the outer air through tiny openings in the underside of the leaf as seen in this cross-sectional drawing. These are the same openings through which air containing carbon dioxide enters the leaf and oxygen is given off. A maple leaf has about 10,000 openings to the square inch. The leaves on just one large maple tree may release over 300 gallons of water on a summer's day. Without the oxygen released in the air by trees and other green plants, animals could not live. When water descends on trees as rain, leaves break the impact of its cutting force. Forest soil acting as a natural reservoir collects the moisture and holds it like a sponge. Many living things could not exist without the shade, moisture, rich soil, and protective shelter afforded by woodlands. Even a small tree lot supports a great variety of life. There are two main types of trees. One of these which is broadleafd is represented by the hickory and the maple. Most broad-leafd or deciduous trees lose their leaves in autumn. From trees such as these, we obtain most of our hardwoods. The other type of tree, which is usually evergreen, has narrow or needle-shaped leaves. Most of these bear their seeds in cones and for that reason are called conifers. Conifers, which are usually soft woods, supply us with much of our timber. Although today we may not rely on trees in the same way as they did in colonial times, the basic needs of shelter, warmth, and food are still present. And there are many other uses. Modern science continues to develop more and more materials. Until today, there are over 5,000 different products made from wood. The film you are seeing is a cellulose product of wood. It is estimated that our needs for timber may double in the next 50 years. How shall we plan to meet such demands? We have already begun by selecting trees for cutting and by reforesting harvested land when necessary. Through tree farming, about 64 million acres of farmland in the United States have trees as their crop. Our national forest system too will help to ensure future timber supplies. Related to the new land conscience has come many new job opportunities. For example, these workers are collecting and classifying seeds from superior trees. From these seeds will come faster growing forms that will be thicker, taller, and straighter. Under good forest management, timber cutting and new forest growth are about [Music] imbalance. The beauty of trees inspires us and their usefulness is never ending. With our rapidly growing population, forests are becoming increasingly important for recreational use. By the year 2000, we will have almost 70% more people. How can we keep up with our recreational needs unless we add to such facilities as our national and state parks? and our new wilderness systems. We can be optimistic about some of the things we are doing, but are we doing enough? Only constant awareness of the necessity for conservation by enough people will guarantee us the forests we need now and for generations to come. [Music]