A Civic Biology Part 12

Which states produce the most hardwoods? From which states do we get most of our yellow pine, spruce, red fir, redwood? Where are the heaviest forests of the United States?

[Ill.u.s.tration: Transportation of lumber in the West. A logging train.]

[Ill.u.s.tration: Transportation of lumber in the East. Logs are mostly floated down rivers to the mills.]

Uses of Wood.--Even in this day of coal, wood is still by far the most used fuel. It is useful in building. It outlasts iron under water, in addition to being durable and light. It is cheap and, with care of the forests, inexhaustible, while our mineral wealth may some day be used up. Distilled wood gives wood alcohol. Partially burned wood is charcoal. In our forests much of the soft wood (the cone-bearing trees, spruce, balsam, hemlock, and pine), and poplars, aspens, ba.s.swood, with some other species, make paper pulp. The daily newspaper and cheap books are responsible for inroads on our forests which cannot well be repaired. It is not necessary to take the largest trees to make pulp wood. Hence many young trees of not more than six inches in diameter are sacrificed. Of the hundreds of species of trees in our forests, the conifers are probably most sought after for lumber.

Pine, especially, is probably used more extensively than any other wood. It is used in all heavy construction work, frames of houses, bridges, masts, spars and timber of s.h.i.+ps, floors, railway ties, and many other purposes.

Cedar is used for s.h.i.+ngles, cabinetwork, lead pencils, etc.; hemlock and spruce for heavy timbers and, as we have seen, for paper pulp. Another use for our lumber, especially odds and ends of all kinds, is in the packing-box industry. It is estimated that nearly 50 per cent of all lumber cut ultimately finds its way into the construction of boxes. Hemlock bark is used for tanning.

The hard woods--ash, ba.s.swood, beech, birch, cherry, chestnut, elm, maple, oak, and walnut--are used largely for the "trim" of our houses, for manufacture of furniture, wagon or car work, and endless other purposes.

[Ill.u.s.tration: Diagrams of sections of timber. _a_, cross section; _b_, radial; _c_, tangential. (From Pinchot, U. S. Dept. of Agriculture.)]

Methods of cutting Timber.--A glance at the diagram of the sections of timber shows us that a tree may be cut radially through the middle of the trunk or tangentially to the middle portion. Most lumber is cut tangentially. In wood cut in this manner the yearly rings take a more or less irregular course. The grain in wood is caused by the fibers not taking straight lines in their course in the tree trunk. In many cases the fibers of the wood take a spiral course up the trunk, or they may wave outward to form little projections. Boards cut out of such a piece of wood will show the effect seen in many of the school desks, where the annual rings appear to form elliptical markings. Quite a difference in color and structure is often seen between the heartwood, composed of the dead walls of cells occupying the central part of the tree trunk, and the sapwood, the living part of the stem.

[Ill.u.s.tration: Section of a tree trunk showing knot.]

Knots.--Knots, as can be seen from the diagram, are branches which at one time started in their outward growth and were for some reason killed.

Later, the tree, continuing in its outward growth, surrounded them and covered them up. A dead limb should be pruned before such growth occurs.

The markings in bird's-eye maple are caused by buds which have not developed, and have been overgrown with the wood of the tree.

Destruction of the Forest.--_By Waste in Cutting._--Man is responsible for the destruction of one of this nation's most valuable a.s.sets. This is primarily due to wrong and wasteful lumbering. Hundreds of thousands of dollars' worth of lumber is left to rot annually because the lumbermen do not cut the trees close enough to the ground, or because through careless felling of trees many other smaller trees are injured. There is great waste in the mills. In fact, man wastes in every step from the forest to the finished product.

[Ill.u.s.tration: A forest in the far west totally destroyed by fire and wasteful lumbering.]

_By Fire._--Indirectly, man is responsible for fire, one of the greatest enemies of the forest. Most of the great forest fires of recent years, the losses from which total in the hundreds of millions, have been due either to railroads or to carelessness in making fires in the woods. It is estimated that in forest lands traversed by railroads from 25 per cent to 90 per cent of the fires are caused by coal-burning locomotives. For this reason laws have been made in New York State requiring locomotives pa.s.sing through the Adirondack forest preserve to burn oil instead of coal. This has resulted in a considerable reduction in the number of fires. In addition to the loss in timber, the fires often burn out the organic matter in the soil (the "duff") forming the forest floor, thus preventing the growth of forest there for many years to come. In New York and other states fires are fought by an organized corps of fire wardens, whose duty it is to watch the forest and to fight forest fires.

Other Enemies.--Other enemies of the forest are numerous fungus plants, insect parasites which bore into the wood or destroy the leaves, and grazing animals, particularly sheep. Wind and snow also annually kill many trees.

Forestry.--In some parts of central Europe, the value of the forests was seen as early as the year 1300 A.D., and many towns consequently bought up the surrounding forests. The city of Zurich has owned forests in its vicinity for at least 600 years and has found them a profitable investment.

In this country only recently has the importance of preserving and caring for our forests been noted by our government. Now, however, we have a Forest Survey of the Department of Agriculture and numerous state and university schools of forestry which are rapidly teaching the people of this country the best methods for the preservation of our forests. The Federal government has set aside a number of tracts of mountain forest in some of the Western states, making a total area of over 167,000,000 acres.

New York has established for the same purpose the Adirondack Park, with nearly 1,500,000 acres of timberland. Pennsylvania has one of 700,000 acres, and many other states have followed their example.

[Ill.u.s.tration: The forest primeval. Trees are killing each other in the struggle for light and air.]

[Ill.u.s.tration: A German beech forest. The trees are kept thinned out so as to allow the young trees to get a start. Contrast this with the picture above.]

Methods for Keeping and Protecting the Forests.--Forests should be kept thinned. Too many trees are as bad as too few. They struggle with one another for foothold and light, which only a few can enjoy. In cutting the forest, it should be considered as a harvest. The oldest trees are the "ripe grain," the younger trees being left to grow to maturity. Several methods of renewing the forest are in use in this country. (1) Trees may be cut down and young ones allowed to sprout from cut stumps. This is called coppice growth. This growth is well seen in parts of New Jersey. (2) Areas or strips may be cut out so that seeds from neighboring trees are carried there to start new growth. (3) Forests may be artificially planted. Two seedlings planted for every tree cut is a rule followed in Europe. (4) The most economical method is that shown in the lower picture on page 114, where the largest trees are thinned out over a large area so as to make room for the younger ones to grow up. The greatest dangers to the forests are from fire and from careless cutting, and these dangers may be kept in check by the efficient work of our national and state foresters.

[Ill.u.s.tration: We must protect our city trees. This tree was badly wounded by being gnawed by a horse.]

A City's Need for Trees.--The city of Paris, well known as one of the most beautiful of European capitals, spends over $100,000 annually in caring for and replacing some of the 90,000 trees owned by the city. All over the United States the city governments are beginning to realize what European cities have long known, that trees are of great value to a city. They are now following the example of European cities by planting trees and by protecting the trees after they are planted. Thousands of city trees are annually killed by horses which gnaw the bark. This may be prevented by proper protection of the trunk by means of screens or wire guards. Chicago has appointed a city forester, who has given the following excellent reasons why trees should be planted in the city:--

(1) Trees are beautiful in form and color, inspiring a constant appreciation of nature.

(2) Trees enhance the beauty of architecture.

(3) Trees create sentiment, love of country, state, city, and home.

(4) Trees have an educational influence upon citizens of all ages, especially children.

(5) Trees encourage outdoor life.

(6) Trees purify the air.

(7) Trees cool the air in summer and radiate warmth in winter.

(8) Trees improve climate and conserve soil and moisture.

(9) Trees furnish resting places and shelter for birds.

(10) Trees increase the value of real estate.

(11) Trees protect the pavement from the heat of the sun.

(12) Trees counteract adverse conditions of city life.

Let us all try to make Arbor Day what it should be, a day for caring for and planting trees, for thus we may preserve this most important heritage of our nation.

REFERENCE BOOKS

ELEMENTARY

Hunter, _Laboratory Problems in Civic Biology_. American Book Company.

Mayne and Hatch, _High School Agriculture_. American Book Company.

Murrill, _Shade Trees_, Bul. 205, Cornell University Agricultural Experiment Station.

Pinchot, _A Primer of Forestry_, Division of Forestry, U. S.

Department of Agriculture.

ADVANCED

Apgar, _Trees of the United States_, Chaps. II, V, VI.

American Book Company.

Coulter, Barnes, and Cowles, _A Textbook of Botany_, Part I and Vol. II. American Book Company.

Goebel, _Organography of Plants_, Part V. Clarendon Press.

Strasburger, Noll, Schenck, and Karston, _A Textbook of Botany_. The Macmillan Company.

Ward, _Timber and Some of its Diseases_. The Macmillan Company.

Yearbook, U. S. Department of Agriculture, Division of Forestry, Buls. 7, 10, 13, 16, 17, 18, 20, 26, 27.

X. THE ECONOMIC RELATION OF GREEN PLANTS TO MAN

_Problems.--How green plants are useful to man._ _(a) As food._ _(b) For clothing._ _(c) Other uses._ _How green plants are harmful to man._

SUGGESTED LABORATORY WORK