R.Z. CALLAHAMR.Z. CALLAHAM is assistant to the Deputy Chief for Research, United States Forest Service, Washington, D.C., leader of Section 22 of the International Union of Forestry Research Organizations, and Chairman of the FAO Panel of Experts on Forest Gene Resources. He served as general rapporteur to the consultation.
A SECOND WORLD consultation on forest tree breeding was held in Washington, D.C. from 7 to 16 August 1969, as the response to a recommendation of the previous consultation organized in Stockholm in 1963. It was sponsored jointly by FAO and IUFRO. The Government of the United States acted as host for the meeting and arranged the accompanying study tours. The Government of Canada cooperated in the arrangements for one of the tours.
Over 200 participants from 40 countries attended the consultation and. in addition to FAO and IUFRO, other international agencies represented were the United Nations Development Programme (UNDP), International Biological Programme (IBP), International Council of Scientific Unions (ICSU), European Economic Community (EEC), Organization of American States (OAS) and the South-Pacific Commission (SPC).
Participants were welcomed at the opening meeting by the FAO Regional Representative for North America, Howard R. Cottam; by T.K. Cowden, Assistant Secretary, Department of Agriculture, on behalf of the United States Government, and by Edward P. Cliff, Chief of the U.S. Forest Service; by John Gray, dean of the University of Florida Forestry School, on behalf of IUFRO; and by R.G. Fontaine, director designate of the FAO Forest Resources Division
In addressing the meeting, Mr. Fontaine gave his view that improvement in the genetic makeup of the world's forests had to go hand in hand with fuller knowledge of site conditions and cultural treatment, since all interacted together and contributed to the ultimate productivity of the forest. A constant difficulty which hampered progress in forest tree improvement was the lack of a full range of properly identified genetic material on which to work. This applied particularly to exotics. FAO's efforts to reinforce and coordinate the excellent work on seed procurement undertaken by a number of different national institutes and universities were now being channelled through the FAO Panel of Experts of Forest Gene Resources, which at its first session in 1968 had drawn up a suggested action programme for seed procurement covering the next decade.
During his address on behalf of IUFRO, Dr. John I,. Gray emphasized the effects of the current population explosion as a result of which the period over which the present population of the world might double had been reduced to about 40 years. In those countries which were overpopulated in relation to food supply, which did not have the finance to import food sufficient to make up the deficit, and which were experiencing rapid population growth, pressures were intensifying to reallocate land from forestry to agriculture or other uses.
At the other extreme, outdoor recreation on forested areas was becoming accepted as a necessity rather than a luxury, as a means of enabling people to relieve some of the tensions of narrowly organized and competitive urban societies. Increases in such new demands on forestry, at the same time as world demand for wood was increasing, had two implications. They tended to restrict the area dedicated to timber production alone and made it all the more urgent to increase productivity on the remainder. They also created greater demand for species and varieties with characteristics such as drought hardiness, low evapotranspiration rates and ability to withstand an unusual degree of soil compaction on heavily used recreational areas.
Again, the need for urban forestry in relation to crowded cities was coming to be more widely recognized. Pressures were already building up on tree improvement programmes financed from public funds, to provide acceptable stock for planting as individual street trees, as belts to provide noise-and dust-barriers and to screen unsightly but necessary municipal functions, and for park, greenbelt and other open space planting. To serve these purposes trees had to have characteristics such as resistance to damage from smoke and atmospherics pollution, heat tolerance, crown shape suitable to the given function and location, resistance to insects and diseases and ability to withstand soil compaction.
In short a number of factors were dictating as never before a need to apply tree improvement technology on a wide scale and for a variety of objectives. First, world needs for wood were expanding. Second, there was increased pressure to divert land now under forests to food production and other uses. Third, there seemed to be a growing demand to use existing forests and to establish new ones for environmental protection and outdoor recreation rather than primarily for wood production. Fourth, the development of trees and management practices for, pollution abatement and for provision of amenities in urban environments was becoming increasingly important. In fact, the management of trees and open-space areas to provide social amenities presented another challenge to foresters and tree breeders. The Washington consultation, it is to he hoped, made a direct contribution toward meeting this challenge.
Conduct of the meetings
T.K. Cowden, Assistant Secretary, U.S. Department of Agriculture, was elected honorary chairman of the consultation, and to the office of executive chairman, John W. Duffield, Professor of Forest Resources, North Carolina State University. The following were elected vice-chairmen: K.E. Andersson (Sweden), W.H. Barrett (Argentina), A.G. Brown (Australia), S.K. Hyun (Rep. Of Korea) and D.E. Iyamabo (Nigeria). The full list of officers and participants is given in Appendix 1.
Practical advantages of tree breeding
This, the general theme of the consultation, was developed under two main headings. First, recent scientific and practical advances were discussed in breeding for specific high-yielding characters. Then discussion covered the planning and execution of tree breeding programmes - from research, through development, to action programmes producing superior varieties of forest trees.
The first discussions were devoted to breeding for groups of characters that affect yield and quality. These are covered by Chapters 1-6 of this issue of Unasylva and summarize the scientific knowledge of inheritance, heritability, combining ability, and other genetic aspects that has accumulated since the first consultation. The results and usefulness of various breeding techniques are reviewed, including species introduction, provenance testing, selection, and hybridization to improve all of the characters affecting yield.
After dealing with factors affecting volume production, like phenology and rate of growth, subsequent meetings turned to the characters affecting quality of stem and wood and to those affecting resistance to insects, diseases, cold, heat, drought, and even air pollutants. A special session was devoted to discussion of breeding trees for values other than wood - that is, trees for beauty and shelter, and trees for products like naval stores, honey, and horticultural crops. Finally, the most difficult concept was covered - breeding for many characters simultaneously.
An overall look was next taken at programmes to produce and use high-yielding varieties. The objective was to understand the interrelationships among research programmes, development programmes, and action programmes, all of which are part of the system for production, dissemination, and use of high-yielding varieties.
Any effort to breed a superior variety of forest tree has three interrelated phases. Research programmes produce knowledge and methods. Development programmes put the research findings into an operational, economic framework for producing the variety. Action programmes mass-produce and use the improved variety to achieve the potential benefits of tree breeding.
These three programmes are linked in time and in investment costs. Characteristically, research in tree breeding is long term in comparison with the time required for development and action programmes to produce and release an improved variety. A critical factor in any breeding programme is the time lag that occurs between research and application. The consultation examined how this could be shortened. The fact that small investments for research usually lead to major investments for action programmes was brought out. Opportunities for reducing costs throughout the system were explored. Models were discussed for analysing the total potential benefits attainable by tree breeding in relation to all costs of the research, development, and action programmes.
Study tours
During the period of the consultation one day was set aside for visits to research facilities of the U.S. Department of Agriculture, to study the tree improvement programme at the U.S. National Arboretum and research projects at the National Agricultural Research Centre on air pollution, photo period and tree physiology. Informal evening meetings were held on mutation breeding (arranged by W.R. Singleton), international provenance trials (IUFRO Section 22 working group chairman P. Bouvarel), resistance of pine to Melampsora pinitorque (IUFRO Sections 22 and 24 working group chairman G. Illy), seed procurement for provenance research (IUFRO Section 22 working group chairman H. garner) and tropical pines (G. Nikles).
An appreciated feature of the consultation was the variety and interest of the study tours. There were three preconsultation tours. The Deep South Tour, started at New Orleans and finished at Jacksonville, covering southern Louisiana, southern Mississippi, Alabama and northern and northcentral Florida. The tour was predominantly concerned with slash pine (Pinus elliottii), with some attention to longleaf pine (P. palustris) and loblolly pine (P. taeda). The South Atlantic Tour started at Macon, Georgia, and finished at Washington, D.C., covering northeastern Georgia, western South Carolina, North Carolina and southeastern Virginia. It was concerned primarily with loblolly pine (P. taeda), with some slash pine (P. elliottii) and other conifers and hardwoods, in the Coastal Plain, Piedmont and mountain areas. The Northeastern Tour started at New Haven and finished at Washington, D.C., covering Connecticut, northeastern New York, central Pennsylvania and Maryland. It featured northern hardwoods, hybrid conifer and poplar plantations and Christmas-tree breeding and selection work.
There were three postconsultation tours. The Lake States Tour covered parts of Michigan, Wisconsin and Minnesota. It featured tree improvement work in progress on species of Pinus, Populus and Betula. The Pacific Northwest Tour was organized in cooperation with the Government of Canada. It was concerned primarily with tree breeding in Douglas fir. The last tour covered parts of California, Nevada and Oregon and featured tree improvement work in Douglas fir, several species of pines and California redwood.
General
1. Tree improvement has an essential part to play in countries where afforestation is becoming increasingly important. In the tropics and subtropics, where growth rates are frequently high, gains from tree improvement may be rapid and substantial. The consultation noted with satisfaction the development of forest genetics and tree improvement programmes in tropical countries since the first world consultation on forest genetics at Stockholm in 1963. The value of such planned programmes to the economies of tropical countries was reiterated and their continuation and expansion recommended.
2. In recognition of the importance of tree improvement programmes in developing countries, multilateral and bilateral aid agencies should continue and expand their assistance in this field. In particular, there is need for more assistance in the form of specialist advice, training centres and fellowships.
3. The consultation considered that there was now sufficient evidence to justify the wide application of the results of genetics research to forestry practices. Government services were, therefore, urged to sustain or enlarge programmes for the mass production of genetically superior trees revealed as suited for use in forest and urban environments.
4. More attention should be paid to breeding forest trees for products other than wood (e.g., tannin, seeds and fruits, honey and beeswax) and for environmental benefits such as soil stabilization, shelterbelts and aesthetic values. Particular attention should be given to trees to be grown to provide social benefits and amenity values in urban areas.
5. The consultation recommended to the Food and Agriculture Organization of the United Nations (FAO), the International Union of Forestry Research Organizations (IUFRO), the International Union for the Conservation of Nature and Natural Resources (IUCN), and the International Biological Programme (IBP) that they: (a) urge governments and institutions to take action forthwith to protect and conserve the germ plasm of forest tree species and provenances that are in danger of extinction; and (b) collaborate in compiling directories of forest tree species and provenances in danger of extinction and of nature reserves, parks, etc., where native forest trees are being conserved.
6. The working groups of IUFRO provide a valuable means of promoting international cooperation but the consultation felt that certain needs were not being met by the working groups presently existing. IUFRO was requested to establish additional working groups dealing with tropical pines and hardwoods; hybridization among species and provenances; and damage to trees by cold, drought and other environmental extremes.
7. The establishment of several regional centres for seed collection and distribution, such as those operating at Canberra, Oxford (England) and Humlebaek, or proposed for Macon (U.S.A.) and Mexico, was greatly welcomed. Such regional centres were necessary for the introduction of new variations, for study of inherited variation, and for conservation of gene resources. Early attention should be given to the possibilities of setting up additional regional seed centres, especially in western Africa and South America.
8. The consultation endorsed FAO's efforts to coordinate and support regional programmes for seed collection, involving also the establishment of an Advisory Panel of Experts on Forest Gene Resources. A wider geographical representation ought to be provided by including on the panel specialists from Asia, western Africa, South America and eastern Europe. The consultation also endorsed the action programme proposed by the panel but stressed that increased financial support would be needed, both from national and international sources, to implement such a programme. It would be useful for FAO to publish periodically in Unasylva the latest information on availability of provenance seed collections and on proposed seed collection expeditions.
9. IUFRO, in collaboration with FAO, was requested to publish a paper on the practical, administrative and costing aspects of seed collecting expeditions.
10. Professional forestry societies were asked to incorporate into their codes of ethics provisions which emphasized the personal responsibility of foresters engaged in planting or seeding: (a) to obtain and record exact information on the provenance, primary or secondary, of the planting stocks or seeds used; and (b) to do their utmost to provide and use only seed or plants of provenances best suited to the local environment. All practicing foresters should regard meeting these responsibilities as a moral obligation.
11. The consultation recommended that the seed certification scheme of the Organization for Economic Cooperation and Development (OECD) be extended to all countries as a means of providing a uniform system for the identification and control of genetic identity of all forest reproductive material.
12. IUFRO was requested to investigate the possibilities of developing and using an international system for rapid retrieval of information from tree breeding literature and experiments, and for standardizing, integrating and mechanizing character evaluation for tree breeding research, as is being done for crops research.
13. Administrators of forestry research agencies and of tree breeding programmes were urged to review the working relationships between geneticists and scientists in other disciplines, in order to provide opportunities for that meaningful multidisciplinary cooperation required to attain the goals of breeding for resistance to pests and environmental extremes, for wood quality and for other traits. Furthermore, broad systems analysis should be applied to breeding programmes to define criteria, values and operating systems.
14. International organizations such as FAO, IUFRO and the European Economic Community (EEC) were asked to lend increased effort to coordinating the work of tree breeders on the regional plane, especially in respect to common species.
15. In order to assure the most efficient use of the limited scientific and professional persons experienced in tree breeding, governments and organizations were urged to provide support by taking into employment technicians who could undertake much of the routine burden of tree breeding programmes.
16. Important research results should be published in periodicals of wide circulation. Papers which have only local distribution should be sent to the Commonwealth Forestry Bureau for notice in Forestry abstracts. Authors and editors of professional magazines were urged to include in published results such vital data as genetic variances, selection intensity, genotypic and phenotypic correlations between traits, experimental design and the error of the estimates, which have in the past frequently been omitted.
17. The consultation requested IUFRO to stimulate and hasten the publication of monographs on the genetic characteristics of important forest tree species, on the lines of those published by the Society of American Foresters and by the Commonwealth Forestry Institute, Oxford, England.
18. The consultation noted the inclusion in the FAO Programme of Work and Budget for 1970-71 of revised editions of the FAO Forest tree seed directory and of the World directory of forestry research institutes. It recommended that these revisions be quickly completed. The new forest tree seed directory should include information on seed certification schemes in operation and on the seed suppliers in each country who complied with these schemes.
19. Recognizing the great benefits derived from this and the preceding consultation, the consultation recommended that a third meeting be held about 1975. Appreciation was expressed for the unofficial invitation to hold the next gathering in Australia, but at the same time strong support was given to the idea of having the meeting in a developing region having a tree breeding programme in the tropics or subtropics. The agenda should be restricted to a limited number of topics that could be explored in depth.
Technical
1. In the planning and evaluation of silvicultural work, greater attention should be given to the genetic makeup of the trees being used and to the genetic implications of the results obtained.
2. Tree improvement in tropical forests being stressed as a necessary development, the following steps were recommended as likely to yield the most rapid progress in the case of indigenous species - establishing provenance trials; accumulating stocks of accessible gene resources; selecting and breeding plus trees; and investigating possibilities for vegetative propagation.
3. Because wide-ranging species are often genetically variable, introduction trials of such species should include samples from several localities within the species range. In the absence of comprehensive genecological studies, the concept of environmental matching can be of value in the initial choice of provenances for testing but in view of successful tree transfers between diverse environments, it should not be applied too rigidly.
4. A sound basis for choosing provenances can only be provided by a thorough study of the genecology of the species, involving determination of its patterns of genetic variation in relation to the environment. It was accordingly recommended that full genecological investigations of all important commercial species be made, with the aim of accurate prediction of advantageous transfers of seed. Particular attention should be given to the complex mixtures of tropical species which have previously been neglected.
5. In the first phase of introducing an exotic, little is known of the suitability of provenances. It was therefore recommended that seed be collected from not worse than dominant and codominant trees of average quality. Not until a later phase, when provenances best fitted for the planting locality have already been identified, should special efforts be made to collect from plus trees.
6. Land races, developed as a result of cultivation in a particular environment, are often superior or equal to the best provenances from the indigenous range. It was recommended, therefore, that seed from land races be used for reforestation and be included in trials of all new provenance introductions.
7. The significance of interactions between breeding and site, cultural systems, management, harvesting and utilization being recognized, the consultation recommended further study of these interactions and their economic consequences. Genotype-site interactions should be taken into account by replicating tests of species, provenances and progenies on a range of sites over several years. The sites tested should be typical of those available for large-scale planting.
8. Recognizing that different species and provenances have different requirements for successful establishment, the consultation stressed the need for studies of suitable techniques for the nursery and field establishment phases as an integral part of the testing process. Sometimes easily corrected deficiencies can mean the difference between success and failure of such tests.
9. Tree breeders should choose efficient mating and field testing designs for progeny trials in relation to breeding plans and resources available. Often a simple procedure such as wind-pollinated progeny tests can give good results.
10. Emphasis needs to be increasingly on estimates of genetic gain obtained in provenance and progeny tests, and of additive and nonadditive genetic variance. With such estimates, genetic gains may be predicted for different systems of breeding.
11. Most breeding programmes have concentrated on improving complex traits such as growth rate and quality of stem and wood; greater attention should be given to simple traits. Among these simple traits, efforts should be directed to those which are most highly heritable and which have the greatest influence on the economic and technical uses of the timber.
12. Correlations among economically important traits vary enormously with species and site. If estimation of genotypic correlation presents difficulties, it may be possible to rely on estimates of phenotypic correlation. Where correlations are negative, the best solution may be to establish a selection index which would result in the optimum economic gain. This solution is often impossible in practice due to lack of accurate economic information. Further attention should, therefore, be given to the development of economic weights through cooperation between tree breeders, economic analysts and the users of forest products.
13. In view of the fact that forest authorities, especially in developing countries, are frequently under pressure to undertake large-scale afforestation projects before adequate data have been obtained about the value of the species concerned, particular attention should be given to establishing correlations between juvenile and adult expressions of important properties, including those of wood quality, and resistance to limiting factors of the environment.
14. Studies are urgently needed of the factors controlling high yield of individuals and stands, in order to improve the efficiency of selection programmes. High yield in volume must always be seen in relationship to quality. Investigations of physiological factors and competition effects were likely avenues by which a greater understanding of yield components could be obtained. The correlation that occurs between phenology and growth rate needs wider recognition.
15. Because of the need for greater standardization in the methods of assessing stem, branch, crown, wood, and resistance characteristics, at least within a species or groups of similar species, IUFRO was asked to give attention to the development and adoption of internationally acceptable guidelines for such assessment.
16. Assessment of stem straightness should be related to the proposed end use of the wood and to the age of the tree. First cycle phenotypic selection for stem straightness has proved to be extremely effective in a number of species and need not involve any loss of volume production. Because breeding for straightness is comparatively easy, breeders were urged not to reject, prematurely species, provenances or plus trees having outstanding qualities but some defects in stem straightness.
17. For naturally straight-growing species, breeders should select for trees which have superior capacity for rapid restoration of a new leader after dieback or breakage.
18. Wood quality should be considered in choosing genotypes and sites for afforestation and cultural techniques to be applied. Particular emphasis should be placed on the determination of wood quality needs, in order to guide the tree breeder. Special attention should. be given to hardwoods and tropical species for which data are especially lacking.
19. IUFRO was asked to give special attention to bringing together, by species, available data on the most efficient method and size of sample for wood quality evaluation in forest stands.
20. Attention was drawn to the potential benefits to be derived from breeding for resistance to pests and diseases, and to the need for careful comparison with alternative approaches such as biological, silvicultural or chemical control. In some cases the success of a species might completely depend on or be restored by, resistance breeding. Furthermore, increased resistance might often be obtained in the framework of a general breeding programme.
21. The need was stressed for more knowledge on phenology and physiology in relation to damage from cold, drought, and other limiting factors of climate and soil.
22. Research related to the mass production of high yielding varieties should be accelerated: (a) to determine the factors which control flower and seed production, including methods of mass controlled pollination, and apomictic seed production; (b) to determine the degree of genetic improvement of progenies from seed production areas; and (c) to develop methods of mass vegetative propagation. Particular attention should be paid to systematic evaluations of rootability of high-yielding varieties.
23. Given the situation that even-aged monocultures frequently represent the most profitable form of forest investment, the consultation warned tree breeders to remain alert to minimize the potential risks of such cultures.
