It is the policy of FAO to review here selected publications which appear to have a direct bearing on the current work of the Forestry and Forest Products Division.
Genetics in Swedish Forestry Practice. Bertil Lindquist. Pp. 173, illus. Chronica Botanica Co. Waltham, Massachusetts, U.S.A. 1948. $3.50.
This work deals with the practical forestry and silvicultural aspects of forest tree breeding and serves as a program and guide for the application of results of genetics work. An extensive bibliography is included. In dealing with the problems of forest tree breeding, probabilities and analogous evidence are the main criteria. Thus long-term progeny tests are essential in appraising the results. Studies begun over 40 years ago have shown that tree form and branch types are hereditary qualities, and the same is true of growth rates; these qualities which determine the value of trees and stands can be used in a practical way.
The forests of Sweden have been utilized for centuries. In the old days when timber of special qualities was required the superior trees were selected and utilized, and thus the genetically superior trees disappeared from the forests. Later, cutting to a diameter limit had more and more effect on the forests, since genetically inferior trees were usually the ones left in residual stands. The process of negative selection of seed trees has became more and more serious, and the end result may be observed in many parts of the country in the form of a severe degeneration of the hereditary constitution of the forests, particularly pine but also spruce, birch, and oak. The practice of leaving broad crowned and intermediate types of trees has been highly undesirable, particularly in pine forests. The usual practices of collecting seed have also contributed to degeneration of the genetical qualities, particularly in the ease of pine. Seed from broad-crowned trees bearing abundant cone crops which were readily available and convenient has accentuated the ill effects of tree selection and utilization.
Knowledge of the heredity of stem form and of branching characteristics should and can be used in the treatment of the stand, as well as in the choice of individuals to serve as seed trees. There is reason to believe that the method of keeping young stands very dense through little or no thinning often yields a stand quality inferior to that obtained with moderate thinning which removes material of poor branching types. Genetic appraisal of the tree material is particularly important when stands of seed trees are being formed. In collecting seed, the use of the new one-legged manganese-steel ladder makes it possible to obtain cones from the genetically superior trees, that is, the dominating trees of genetically good stands. Thus mapping of pine stands from a seed collecting point of view has been under way for about four years, and the stands have been classified on the basis of the frequency and proportion of superior trees in the stand. Three classes are recognized: (1) plus areas (2) normal areas; and (3) minus areas. In plus stands, the undesirable broader-owned and slow growing trees should be removed quickly, and cones should be collected and moderately good cone seasons from trees which will yield about one liter of cones. Normal stands should also be cleared of the broad-crowned trees. Sparse seed tree stands of the genetically desirable trees will be left, and most pine seed should be gathered from such stands by trained teams of workmen under supervision. Minus areas are undesirable because removal of broad-crowned trees amounts to virtual clear-cutting.
The importance of climatic phases has long been known, and a moderate transference of both pine and spruce from the south to the north, or from lower to higher altitudes, meets with little climatic difficulty. A schedule showing the effect of transference has been worked out for troth pine and spruce in northern and southern Sweden. In nursery work, heavy culling of the stock is necessary to eliminate particularly small and weak-growing plants, and those with bad branch form and weak leaders.
The annual requirement of conifer seed is estimated at 60 tons, but the average annual production has been only about half this figure. Thus special measures must be taken to obtain genetically superior seed in the quantity required to reconstitute the large areas of forest on which only genetically inferior seed trees remain.
Plantations for seed production seem to be a feasible means of speeding up the production of superior seed. Several methods may be applied to superior individual trees at an early age to stimulate flowering and seed formation. These are strangulation, girdling or bark ringing and grafting. Grafting in itself gives rise to richer flowering and fruit setting. Fear that superior stock grafted on inferior may inherit the inferior qualities is now known to be groundless. It is estimated that a seed plantation of pine and spruce should normally yield a yearly crop of 50 kilograms per hectare. To obtain 60 tons of seed it would therefore be necessary to have a total plantation of 1,200 hectares (1¼ million trees at the rate of 1,000 trees per hectare). The requirements for oak, birch, ash, and beech plantations are relatively small. Since the difficulties of forming seed plantations are considerable, it is particularly important that grafting of coniferous trees be done only by people with special skill and that the areas be selected carefully so that grafted trees will not be exposed to excessive temperature changes during the period when the graft is uniting with the stock. These seed plantations will be valuable in producing elite seed trees. It is estimated that individual elite trees could be increased at a single center to 10,000 plants in about 10 years. Thus for a given provenance zone there would be no difficulty in propagating 60,000 to 100,000 individuals from the 6 to 10 elite trees chosen, and only about 100 pines should be necessary for all the provenance zones of pine. Sweden has been divided into 10 zones for pine and 6 for spruce. It is important that seed plantation work should be strictly controlled by the government from the start.
An essential step in seeking to improve both quality and quantity of trees and stands is the selection of elite trees, that is, the most extreme plus valuations in branching, timber quality, and growth. A combination of all these qualities is highly uncommon, and balancing of the different factors from the genetic viewpoint is therefore important. Since the elite trees are to become the mother trees for future seed plantations, progeny tests of each selected tree should be started promptly so that the initial appraisal may be verified later. Progeny tests should run for a period of at least 30 to 40 years.
In selecting elite pines, one requirement is that the stems should have at least 50 percent more volume than the average of the three next biggest trees in the immediate vicinity. Moreover, trees which have poor heartwood formation should be rejected. In the inventory so far conducted, about 3,000 elite pine have been registered, and progeny tests have been started from all these trees which have set cones. About 10 percent have been selected for a more detailed examination and progeny testing. About 100 of the selected trees have given very superior progeny with quick growth and have been chosen for grafting and mass breeding during the next years.
Requirements for spruce are mass superiority in growth and a branch formation which is not too coarse. German spruces have been found in progeny tests to possess better growth than the Swedish spruce. In making, progeny tests, the susceptibility of the young plants to frost should be taken into account.
The choice of elite birch trees is complicated since the value of this species depends on wood quality for ski wood furniture wood, and various special types of plywood. The boles should be straight and the base of the stem round. A much stricter control of the wood properties is necessary for birch than for pine and spruce. In the inventory of elite trees fee birch, browned curly-grained birch flamy birch, hard glossy birch, and soft glossy birch have been recognized as types of wood suitable for industry. These are fast growing varieties.
Oak has suffered particularly from degeneration through wrong treatment, and protection of the remaining superior oak is particularly urgent. Requirements for elite trees are very strict; they include straightness and length of bole, good branching, minimum number of epicorms and light, well-developed, evenly colored heartwood. So far, only about 30 elite oak trees have been found in the whole of Sweden, and this illustrates the importance of establishing seed plantations of elite trees.
The requirement for ash is that the heartwood of the trees should not be brown. Seed plantations could soon be established, and planting stock produced for large areas. Requirements for elite trees of alder, elm, beech, maple, etc. generally include rapid growth, straight stem, and relatively good type of branching. Among exotics, only some species of poplar, larch, Douglas fir, and Sitka spruce are regarded as worth genetical work in Sweden.
At present, it is only by agreement and persuasion that elite trees and plus stands can be preserved intact, and there is always danger of damage from too much and careless climbing for the cone harvest. It is therefore essential that more reliable procedures for preserving the genetically superior stands and elite trees be worked out.
It must be recognized that for a good many years high class seed will not be available for general use. The government should see to it that particular care is given to selecting choice and accessible sites, putting the right species on the right soils, and protecting plantations of elite stock from forest grazing.
Genetical knowledge should be applied in thinning the present young stands, particularly pine, birch, and oak. In this way, great improvement may be expected. In some new stands the sowing of better seed may result in 100 percent increase in quality for beech and oak, and lesser quality improvement for spruce and pine. Increased volume production should also be obtained from plus stands since the breeding material is derived from the dominant stands. There is also the possibility that the genetically desirable narrow-crowned trees may be able to grow closer together than the broad-crowned trees. All in all, increased growth is to be expected. Once the most desirable tree form is available, it will be possible to increase the spacing in plantations and thus reduce both planting and tending expenses. This will be important because of the migration of forest workers to the cities and the increasing difficulty of obtaining sufficient labor. The effect of increased growth in elite stands is likely to be reflected in somewhat shorter rotations.
Coniferen, Ephedra en Ginkgo. (Coniferae, Ephedraceae, and Ginkgoales). P. den Ouden. Pp. 444 + 160 illus. H. Veenman & Zonen, Wageningen, Holland. 1949. $7.75 in the U.S.A.; $8.50 in Canada.
The author describes about 900 species and varieties of conifers which can be found growing in the Netherlands and Belgium. Important details are given regarding species of interest to commercial growers and to landscape architects and garden owners, including the cultivation of varieties and protection against insects and pests. The author is preparing a supplement covering conifers and related species growing all over the world, and would be glad to hear of new varieties. His address is: Rozenlaan 50, Boskoop, Netherlands.
Tree Crops. J. Russell Smith. Pp. 408 illus. The Devin-Adair Company, New York. 1950. $6.00.
The Fifth Session of the FAO Conference (1949) supported the suggestion of the Delegate for Mexico that the planting of trees, particularly on hillsides, which could make a direct contribution to food supplies for animal and human use, should be explored in connection with the study of reforestation methods. In his fascinating and thoughtful book, Dr. J. Russell Smith, who is not only a horticulturist but also an economist, writer, and widely travelled geographer, makes a solid contribution towards this important study. After wide travel he is justly perturbed at the spread of soil erosion, the cycle of "forest, field, plough, desert" and the increasing incidence of the transfer of the agriculture of the flat plain to the hills, with the devastating results so well known and so plainly to be seen throughout most of the world. His way out is tree crops, and his plan is an institute of mountain agriculture. He demonstrates the desirability of tree crops on poor mountain land crops that will provide not only wood but also food for both animal and man, crops that can be managed in connection with grazing and agricultural crops proper.
Forestry and Flood Control in Japan. C. J. Kraebel. Pp. 29. General Headquarters, Supreme Commander for the Allied Powers, Natural Resources Section, Tokyo, Japan. (Preliminary Study No. 39.) 1950.
Flood and erosion damage in Japan has developed to a stage where it has become a national emergency. Losses of food crops damage to paddy lands, erosion of soils, and destruction of life and property are seriously retarding the economic rehabilitation of Japan. In recognition of the seriousness of this situation, the Supreme Commander for the Allied Powers invited Mr. Kraebel, a watershed management specialist of international reputation, to investigate the extent of the influence of forests on flood control in Japan. The significance of this study is indicated by the feet that in Japan, which is only four-fifths the size of California, the annual flood losses now exceed those of the entire United States and are steadily increasing. In 1942 an estimated 133,000 acres (53,800 hectares) of agricultural land and facilities were damaged and by 1948 this had increased to 1,915,000 acres (775,000 hectares).
Basically the problem is severe because of the rugged topography, high intensity rainfall, pressure of a dense population on the land, and steepness of the river gradients. But it is clearly evident that the increase and intensification of flood damage has been caused by the unwise use of large areas of mountain lands. The relationship between denudation of forests and flood damage to agriculture is indicated by the changes between 1929 and 1550: denuded forest land increased from 441,000 acres (178,000 hectares) to 7,355,000 acres (2,977,000 hectares), and the area of damaged farmland increased from about 5,000 acres (2,000 hectares) to 75,000 acres (30,000 hectares). It is evident that an expanded and vigorous program of flood control, with particular emphasis on headwaters areas, is imperative. A great deal of work on levees and similar works has been done in the lowlands, but these are not generally successful.
The general recommendations for flood control programs through forestry work include: (l) co ordination of governmental efforts, (2) preparation of comprehensive plans for each important watershed, which will integrate for the first time the programs for headwaters, middle stream, and downstream areas; (3) upstream improvement work through planting, erosion control structures, and other improvement works, the need for this being indicated by the feet that in 10 important reservoirs the sedimentation has reached 47 percent of the reservoirs' capacity in a period of less than 14 years; (4) equalization of forest use to spread cutting more evenly, since more accessible areas are presently severely overcut; (5) research based on training of selected Japanese technicians in research methods at American centers; (6) in-service training so that officers may be properly indoctrinated in the problems and methods for solution of flood control through forestry.
Specific recommendations include: (1) abolition of clear-cutting, the present ruling practice, so that sufficient forest cover and litter may remain on the ground to minimize flood runoff; (2) prompt planting of overcut forest land with limitation of the interplanting of food crops; (3) building of a more adequate system of forest roads to remove the necessity for log skidding and the present practice of skidding directly down the slope; (4) control of the collection of litter so-that enough litter may remain on the ground to control runoff and erosion; (5) control of the use of mountain grasslands which are presently overused for grazing, (6) control of conversion of forest to grasslands to areas with slopes of less than 40 percent; (7) control of cultural practices on upland farming so that terracing and other methods may be applied in lieu of the present practice of up and down hill arrangement of row crops.
The costs of such a program will, of course, be great, but the alternative of accepting increasing losses would lead to really severe trouble in a fairly short period.
Anuario Brasileiro de Economía Forestal, 1949. (Brazilian Yearbook of Forest Economy, 1949.) Pp. 600. Second Yearbook. Instituto Nacional do Pinho, Rio de Janeiro, Brazil. 60 Cruzeiros. (1948 and 1949 Yearbooks - 100 Cruzeiros.)
Because books and periodicals dealing with forestry and forest products problems in Latin America are still relatively scarce, the publication of this yearbook in Brazil is of particular interest. The volume for 1949 has an introductory statement by the President of Brazil stressing the importance of proper soil conservation and an article by the President of the Instituto Nacional do Pinho summing up the work carried out by the institute since its creation in 1940 and explaining its present organization and future programs. There are 37 other articles written by the staff of the institute and by Brazilian and foreign technicians on various forestry and forest utilization problems. Of the many interesting articles, those dealing with the following subjects should be mentioned: The Pine Forests of Brazil, Timbers Exported by Brazil, Brazilian Timber Prices 1939-1948, Sawmilling Schools, Brazilian Timber Used for Sleepers, The Quinine Tree and Its Cultivation, and The Experimental Plywood Plant in Curitiba. The articles, each of which is accompanied by a summary in English, give a concise picture of the problems confronting the Brazilian authorities and technicians in their task of arriving at a sound program for the conservation and development of the forest resources, and they also point, up the research work and modernization programs needed to help the forest industries to produce and export a better product.
There is a list of commercial tree species, with a standardized nomenclature and a description of their physical and chemical properties, as well as 37 pages of statistical data on production, imports, and exports.
Some Geographic and Economic Aspects of the Cork Oak. Victor A. Ryan. Pp. 116, illus., 10 maps. Crown Cork and Seal Company, Inc., Baltimore, Maryland, U.S.A. 1948.
A former president of the company of which Mr. Ryan is Director of Research initiated a project in 1939 to establish a domestic cork oak industry in the United States of America. Plantings have gained such impetus, especially as a result of cork being classified as a "critical material" in the recent world war, that the author decided to make this comprehensive study to supplement earlier work.
This interesting study, copies of which the company has kindly offered to supply to-those interested, includes chapters on The Natural Distribution of the Cork Oak, Geographic Environment of the Cork Oak, Apparent Rate of Growth of Cork Oak, and The Cork Potentiality of the U.S.A.
1950 Yearbook of Forest Products Statistics
Fourth Yearbook of international forest products statistics to be published by FAO. It contains 1949 official information on production and trade and revised data for 1948, as reported by more than one hundred countries and territories in reply to a standard questionnaire.
The statistical tables are preceded by a short text which gives some salient features of the 1949 world situation. World and regional figures given here include estimates for non-reporting countries; in the statistical tables, the totals are for reporting countries only.
This Yearbook provides the most consistent and useful body of international forest products statistics now available. The 43 tables cover the following topics:
Sawlogs & Veneer Logs - Trade
Pulpwood - Trade
Pitprops & Trade
· PROCESSED WOOD
Lumber, Plywood, and Sleepers
· WOOD PULP, NEWSPRINT, PAPER AND PAPERBOARD, AND FIBERBOARDS
· WORLD TRADE - Summary
Volume of Imports and Exports
Value of Imports and Exports
· COMPARATIVE DATA
Forest Products Balances
Per Caput Consumption of Forest Products
1950 YEARBOOK OF FOREST PRODUCTS STATISTICS, published by the Food and Agriculture Organization of the United Nations, 1201 Connecticut Ave., NW, Washington 6, D.C., U.S.A. Bilingual: English-French, with Spanish supplement. Paper bound, 8 ½ x 11 in., 182 pp. Price US $2.50, 17s. 6d. Available in national currencies when orders are placed through local FAO sales agents.