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THE UTILIZATION OF EUCALYPTUS
BY C. STOWELL SMITH
Forest Service, U. S. Department of Agriculture.
CCORDING to statistics collected by the Bureau of the Census, the amount of hardwood cut in 1906 showed a decrease of over 15 per cent from the amount cut in 1890. The remarkable thing about this decrease is, that during the same period 1899-1906, the cut of softwood timber increased over 15 per cent and structural materials generally showed a substantial increase. It is proved, then, that hardwood users are facing a condition of serious shortage in supply.
One of the results of this shortage has been a more comprehensive investigation of the qualities of those hardwoods which up to a comparatively few years ago were not found in the market in large quantities. Examples are the tupelo and birch. Both of these woods are of great value for furniture and other high grade use, and yet were practically unused for such purposes until the price of oak rose to such a point that the discovery of a satisfactory substitute became necessary. In 1899 the cut of birch in the United States was 132,601,000 feet, while in 1906 it rose to 370,000,000 feet, an increase of 179.4 per cent. In 1906 the reported cut of tupelo was 47,882,000 feet. Figures are lacking for the year 1899, as the cut was so small that it was not considered worth while to collect the statistics. It is safe to predict that the demand for hardwoods will never lessen. It is also fairly certain that practically all of the native woods which might prove to be worthy substitutes for the vanishing oak and other well known and widely used hardwoods, have been investigated and, where satisfactory, brought into the market. The available supply of all such
hardwoods has been estimated by various authorities, the highest estimate made being 400 billion feet. It is assumed that the annual consumption is not less than 25 billion feet. Of this about 8 billion feet represents the trees actually cut into lumber, and the rest is distributed between railroad ties, poles, piles, posts, fuel and the waste occurring in lumbering and manufacture. At this rate, about 16 years will see a hardwood famine of sufficient proportions to seriously cripple a large number of important American industries if some means of relief are not discovered.
What are the possibilities for relief? First, the importation of hardwoods from foreign countries; second, the substitution of other materials such as iron or steel to take the place of the vanishing hardwoods; and third, the growing of hardwoods in sufficient quantities to supply the ever-increasing demand.
The foreign countries capable of furnishing hardwoods which might be satisfactorily employed to take the place of our own woods, in many cases consume a large share of their output. In most cases where this is not true at the present time it will be true in the near future, due to internal development of wood-using industries. Our possessions, as well as Mexico, the East Indies, and the countries in South America, will be able to furnish the finer cabinet woods for some time, but the supply is limited. Furthermore, the available foreign woods are largely cabinet woods, and, except in a few cases, do not offer successful substitutes for the cooperage, vehicle, agricultural implement, and other wood-using industries of great and increasing importance to this country.
If foreign supplies cannot be depended upon to relieve the situation, the alterna
Cutting a stand of blue gum. Stumps cut low, and trees piled ready for cutting into fuel wood. Trees four to ten inches in diameter six years after planting
tive of using other material than wood in the manufacture of articles now commonly made of wood, presents itself. Already considerable time and money has been spent in developing steel implements, furniture, cars and even interior finish; and concrete alone and in combination with steel has been wisely used in general construction. Attempts have been made to employ softwoods to take the place of hardwoods, but on account of a lack of strength, elasticity and toughness, such substitution has been unsuccessful. In spite of the development of substitutes for it, however, the consumption of hardwoods has steadily increased, and new uses have been found. Probably 20 per cent of the total hardwoods produced in the United States goes into furniture. Metal furniture will never be acceptable, and softwoods will not give the necessary hardness and rigidity. It is hard to conceive the condition of the furniture industry if the hardwood supply fails. Another important industry is the manufacture of cooperage. What will become of the cooperage industry if oak disappears? Wagons, carriages and automobiles con
sume the best grades of hickory and oak. Vehicle manufacturers are making strenuous efforts to try out all possible woods, but up to the present time no satisfactory substitutes for hickory, hard maple, oak, ash and elm have been found.
The need for hardwoods is apparent unless some of the most important industries are to be seriously crippled or destroyed. We cannot depend upon a foreign supply. We cannot count upon the development of satisfactory substitutes for all purposes. The last alternative, therefore, is to conserve the present supply of hardwood by wise use and to provide for the impending hardwood famine by planting species which will make timber suitable for the various hardwood using industries. At the present time, attempts are being made to cut down the waste which occurs in logging and manufacturing high-grade hardwoods. This is especially true of hickory and white oak. But such economies will not be great enough to materially affect the total supply. It is therefore largely a question of caring for the present young hardwood growth until it reaches maturity, and of
planting such species as are best adapted to our soil and moisture conditions. It is true that certain hardwoods will grow in certain parts of the Eastern United States to good advantage. The rate of growth in the Appalachian Mountains, for instance, is rapid, and the land is particularly well adapted to permanent forest growth, being as a rule unsuited. for agricultural purposes. One of the soundest business policies, therefore, which the people of the United States have an opportunity to adopt at the present time is the policy of placing the nonagricultural lands in the Appalachian Mountains under conservative forest management for the production of hardwoods. If this policy is adopted at once, much good will be accomplished, but on account of the damaged condition of the present Appalachian forest it will take many years of careful and systematic protection and management to bring it to a condition of maximum yield per acre. In the meantime, however, the seemingly inevitable hardwood famine looms up and something must be done to meet it.
The most promising solution of this difficulty seems to be the growing of eucalyptus in those sections of the United
States which are adapted to its growth. Such territory is limited, as the eucalyptus will not stand extremes of cold or heat. Up to the present time results seem to indicate that portions of California are particularly well suited to the growing of these, interesting trees. In fact, there seems to be little question but that they will grow, and grow successfully, providing the different factors influencing growth, such as temperature, soil and moisture, are taken into consideration in selecting the species to be planted.
What are the qualities which recommend eucalyptus? First, it is probably the most rapidly growing hardwood which has ever been planted in this country. This is taken for granted and consequently will not be discussed. Second, certain species appear to possess certain physical characteristics which give promise of adapting them for use in the manufacture of cooperage, vehicles, tool handles, plow beams, frame work for agricultural implements, insulator pins, furniture, interior finish, flooring and in fact wherever the best grades of hardwoods have proven successful. In addition to these high grade uses may be mentioned
Unthinned sprout stand of blue gum five years old. Trees four to fourteen inches
railroad cross-ties, piles, poles, posts, dimension material, cordwood and charcoal. The first mentioned class should, of course, be made up of the straight, clear timber, and the second of knotty trees or trees having other defects which make them unfit for the manufacture of clear lumber.
The question is often asked: "Isn't it true that most of the species of eucalyptus planted in the United States have been successfully utilized in their native habitat?" This is the case, but care must be exercised in adopting Australian or Tasmanian results as applying to the same species grown in this country. There are two main causes which may affect such results. First, foreign experience in utilizing these species has been confined largely to mature timber; and second, conditions of soil, moisture and temperature are not identical with those found in this country. It is absurd to expect that the groves of eucalyptus which are being planted at the present time in the United
States will be allowed to grow for one hundred years or so, until they have reached a rate of growth and physical condition comparable to the species in their native home. The average business man is anxious to get his returns in the shortest possible time; consequently the maximum rotation allowed for growing eucalyptus will be not more than 30 or 35 years, and very few groves will reach an age of 25 years. These facts bring out forcibly the need for a comprehensive, detailed study of the physical characteristics and uses of our rapid-grown and young timber. The results obtained in foreign countries are highly suggestive and are sufficient warrant for the extensive planting which is being done, but such an important industry should have definite reliable, first-hand reliable, first-hand information. which can be directly applied to our conditions. It is with the idea of furnishing this information that the Forest Service is undertaking a study of the utilization of eucalyptus actually grown in California. In
co-operation with the University of California, extensive strength tests on all of the most important species are being made. In co-operation with various manufacturers and users of hardwoods, the most available species, Eucalyptus globulus, is being made up into staves, vehicle parts, tool handles, agricultural implements, cross-arms, insulator pins and furniture. In co-operation with individuals and independently, an exhaustive study of methods of seasoning blue gum (Eucalyptus globulus) is under way.
The average strength values which have been obtained up to the present time for green Eucalyutus globulus, based on tests
of small, clear specimens, approximately 2x2x30 in., are: Bending modulus of rupture or breaking strength, 11,510 pounds per square inch (139 tests); maximum crushing strength parallel to grain, 4810 pounds per square inch (198 tests); crushing strength perpendicular to the grain, 1310 pounds per square inch (84 tests); and shearing parallel to grain, 1640 pounds per square inch (113 tests.)
(As the study is not yet completed, the results must not be considered final.)
Taking the common blue gum, Eucalyptus globulus, in a green condition, as 100, the ratios of the strength of the others to it are as follows: