Mangroves: A fragile ecosystem
What is meant by managing gene resources
Agricultural publications catalogue
Fire and forests in the Mediterranean
Reforestation with maritime pine
History repeats itself - again
Agroforestry down under
Trees in the Australian forest
All about trees
Mangroves du Sénégal et de la Gambie. Claude Marius. Ph.D. Thesis. Paris. ORSTOM. 1985. 357 pp.
Mangroves, one of the most endangered ecosystems on our planet, cover an area of 15 million ha in tropical Africa, Asia and the United States. Land vegetation and marine fauna live together in a precarious equilibrium that is still not well understood. What is clear, however, is that this equilibrium is easily destroyed.
The term mangrove was formerly used to designate the plant formations of certain coastal plains in tropical regions. Today it characterizes entire ecosystems in the estuaries of many tropical regions.
Three factors determine the establishment of mangroves. First and foremost, climate: mangroves need high temperatures in order to grow. Second, the extent of the intertidal area: deltas, estuaries and lagoons are the favoured sites because they provide large intertidal stretches. Finally, salinity: the finest mangroves develop in humid equatorial and tropical regions where the waters are free of salt for much of the year.
In his Ph.D. thesis. Claude Marius studies formations in Senegal and the Gambia. Those of the Casamance and the Saloum in Senegal grow in inlets that are directly exposed to the influence of salt sea water. They are characterized by two plant formations: mangroves, represented by six species, and the halophytic or brackish swamps known as tannes. The mangroves of the Gambia grow in a real estuary where the fresh water neutralizes the impact of the sea. The Gambia, unlike the Casamance and the Saloum, is sufficiently powerful to enable the fresh water to push back the salt water for a good part of the year.
Marius examines this ecological environment from the point of view of climate, flora, marine and terrestrial fauna and hydrology. He analyses the morphology of the mangrove soils by studying six samples and examines the main factors in the pedogenesis of these soils, in particular the sulphur on which acidity depends and the soluble salts responsible for salinity.
In the past many products of the mangroves were in common use, particularly in nutrition, medicine, agriculture, fishing and wood production. Today mangrove areas are used in many countries for agricultural purposes, particularly where there is high population pressure. The main crop grown in them is rice. The thesis devotes an important chapter to the utilization of these soils and highlights the many constraints to efforts at management. Most mangrove soils, which have a fine texture and are not very permeable, are subject to various kinds of flooding. Salinity, difficulty of access and the instability of the unreclaimed land makes clearing operations, particularly by mechanized means, very arduous.
The presence along the edges of the tributaries of the Casamance of large untapped areas of mangroves has prompted the Senegalese Government to launch a vast management programme for this region. Utilization of the mangroves is expected to permit balanced and harmonious development of the activities connected with this environment, i.e. fishing and aquaculture in the tannes and rice-growing thanks to the construction of dams to ensure a supply of fresh water at the end of the rainy season.
It must not be forgotten, however, that both management work and the modification of traditional agricultural techniques may upset the fragile equilibrium of the ecosystem. It is therefore advisable to protect the weak points, particularly the banks, which are subject to erosion; and to ensure the protection of the land bordering upon the mangroves.
Gestion des ressources génétiques les plantes. J. Pernes. Paris. Agency for Cultural and Technical Cooperation, 1984. 2 vols. 558 pp.
The disappearance of arable land because of erosion and irrational land use, and the heavy losses caused by pests that have become immune to pesticides, make it urgent to devise more effective agricultural techniques and to improve crop material. In the developing countries such measures are even more urgent, because the food security of growing populations depends on them.
It is against this background that the Agency for Cultural and Technical Cooperation, an intergovernmental organization set up in 1970 by the Treaty of Niamey, launched a two-pronged project several years ago: first, the storage, exchange and processing of data through field inventories, laboratory analysis and the establishment of a computerized data bank; and, second, an effort oriented specifically toward application. This book is the result, prepared by a team of specialists under the direction of J. Pernes. It consists of two parts: a manual and a series of monographs.
The immediate purpose of the manual is to enable readers to understand what is meant by "managing gene resources" and at the same time provide the instruments for building up their own store of methods and techniques. (For a more specific view of the role of managing forestry genetic resources, see "Genetics and the forests of the future" by Gene Namkoong in Unasylva, 38 (152): 2-18 - Ed.).
The manual consists of five chapters. The first examines the organization of species complexes, i.e. plants which under natural conditions can exchange genes by hybridization, either directly or through intermediate plants. The authors point out that building up, conserving and evaluating gene resources do not involve merely maintaining, labelling and listing. The diversity of a group of cultivated plants is, in fact, a dynamic entity in constant evolution.
The manual then analyses strategies for exploration, whose aim it defines as being the collection of living material incorporating the greatest possible variability. Efforts aimed at the genetic improvement of a plant must, in fact, be exhaustive; they must be designed to assemble as much knowledge as possible about the plant in question.
Third, regarding the evaluation of resources, the authors point out that plant material accumulated during investigations may consist of thousands or even tens of thousands of samples. The evaluation programme will therefore have to analyse these samples while taking into account all the problems posed by future uses. Agronomic evaluation will be useful only if it is conducted under the ecological conditions of the plant improvement project.
Fourth, with regard to the conservation of gene resources, the manual points out that gene potentials can be safeguarded by conserving wild forms in situ and cultivated forms in traditional agricultural areas. It notes, however, that the development of modern, high-yielding agriculture linked to the growth in world population and to industrialization has resulted in the disappearance of traditional cultivars in favour of a limited number of selected varieties.
Fifth, the chapter dealing with data bases and their use for statistical purposes constitutes a handbook of the biological knowledge necessary for information workers who want to adapt general data bases to the particular problems of gene resources.
The author stresses that there are very few cultivated plants that are not widely cultivated outside their zones of origin and that very few indigenous plants are being used by agriculture in only one country. The result is that most gene resources escape the attention of the users. Two solutions are possible: the constitution of an international organization to manage gene resources, which would be considered the property of all humanity and not to be appropriated by special interest groups; or the establishment by each country of its own gene banks.
The monographs give some concrete examples of the system outlined in the "methodology" section. Four species Panicum maximum, coffee, rice and millet - are examined. The fodder plant Panicum maximum was chosen in view of the need to encourage research on both the management of natural pastures and the creation of artificial ones in order to reduce the growing deficit of animal protein. Investigations conducted in Côte d'Ivoire, Kenya and the United Republic of Tanzania have resulted in a collection of living specimens being installed on a plot in the ORSTOM Centre in Côte d'Ivoire.
In coffee, work has been concentrated on improvement within each species and classification of the most promising species, with emphasis on C. canephora because of its vigour and resistance to diseases.
Rice growing in West Africa, the authors point out, is of very ancient origin, probably predating the introduction of rice of Asian origin. However, during the last 50 years the implementation of rice-growing projects and the promotion of modern varieties have endangered the survival of the indigenous species. Research is now concerned mainly with identifying and ascertaining the adaptability and utilization potentials of the native forms.
As regards millet, the staple cereal throughout the Sahelian zone, recent improvement programmes have been concerned with decreasing the ratio between straw and grain and maintaining genetic variability.
The work is completed by a large bibliography and a number of tables and illustrations.
LODGED RICE INDONESIA a need to preserve wild species
NEW RESEARCH INTO COFFEE SPECIES an attempt at genetic management
Publications of the International Agricultural Research Centres. Consultative Group on International Agricultural Research (CGIAR). Los Baños. Laguna, the Philippines. International Rice Research Institute German Agency for Technical Cooperation (GTZ). 1985. Paperback. Price: US$13.70 including airmail postage and handling.
The International Agricultural Research Centres (IARCs) focus modern agricultural research on the crops and livestock that provide 75 percent of the food for developing nations. The Centres are major publishers of books, periodicals, slide sets, films and other educational materials on agricultural science and technology for developing nations.
The International Rice Research Institute (IRRI) is copublisher of this agricultural publications catalogue, which includes a detailed subject index, and it is handling worldwide distribution. The catalogue is a compilation of the major publications of the IARCs sponsored by the Consultative Group on International Agricultural Research (CGIAR) - including the International Board for Plant Genetic Resources - but it includes various non-CGIAR-sponsored centres as well.
La prevenzione degli incendi boschivi - i problemi e le techniche della difesa. G. Calabri. Edagricole, 1984 184 pp.
In his manual on the prevention of forest fires - a subject on which he wrote an article for Unasylva, 35 (141) - Giancarlo Calabri goes back to the beginning of time to show how fire, a symbol of life in mythology and religions throughout the world and, in some philosophies, the principle of all things and the centre of the universe, has become, because of the uncontrolled use human beings have made of it, a symbol of destruction and death; and, in the context of this book, a symbol of the destruction and death of the forest.
Calabri, a specialist in this field, first describes the behaviour of fire through the image of a triangle whose sides consist of fuel, oxygen and heat. He then passes and this is one of the most important chapters - to the causes of fires. He recognizes only one really significant natural cause: lightning. He rejects the theory of auto-combustion, which never occurs in forests and has merely become a convenient alibi. It is human actions that are really responsible for fires: negligence and, in many cases, malicious intent. This is compounded by the growing use of the forest for recreational purposes (picnics, camp-fires, fireworks). But agricultural pressure on wooded land and traditional agricultural and pastoral techniques also bear some of the responsibility.
Calabri then tackles two of his main themes: prevention and detection. The first comprises all measures aimed at preventing fires from starting or spreading and at reducing the damage as much as possible. The second concerns fire-fighting operations, which cannot be effective and economical unless the behaviour of the fire and its intensity and extent are assessed promptly and the necessary defensive measures are taken. It is to the latter that the most important chapter in the book is devoted: to active fire-fighting, describing the techniques for controlling and extinguishing fires: manual and mechanical tools; the use of tractors to open up tracks; hydraulic pumps; and land and aerial equipment.
The book is clear, precise and instructive and addressed both to specialists and to the public at large Special mention must be made of the illustrations by the author, which humorously portray certain situations that might face fire-fighting teams.
Fay Banoun, Rome
La culture du pin maritime en Aquitaine. H. Chaperon. Paris, AFOCEL, 1986. 231 pp.
This book studies reforestation with maritime pine in southwestern France, an area where sandy soils and humid heathlands predominate.
One long chapter is devoted to plant breeding material (seeds, cuttings) and illustrates how maritime pine nurseries are organized. Another describes the different stages in reforestation work: drainage, clearing and working of the soil, fertilization, and the choice of the most suitable species and variety.
Chaperon describes three silvicultural methods. The choice from among them will depend on the ecological conditions of the site (intensive silviculture, ligniculture, tree-culture). The importance of careful ecological and economic analysis before any afforestation work is undertaken is emphasized.
Intensive management of the stands is also essential, including maintenance work, disease control, fertilization, thinning and pruning.
Finally, a study of the economic aspects has shown that the higher the initial investment the more production increases and hence the greater the profits.
TAKING THE LONG VIEW a new history of Australian forestry
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Recent books about Australia |
A history of forestry in Australia. L. T. Carron. Australian National University Press. ISBN 008 029874 5. Price: A$40.
Dr L.T. Carron chronicles the evolution of the various distinct styles of forestry that developed in Australia from about the time that the Europeans arrived up until the late 1970s.
A book on the history of forestry is quite a rarity so much so that this book prompted the reviewer, who has been incarcerated within various forestry bureaucracies for the past 30-odd years, to ponder, "What is history?" One pseudo-definition is that "history is the essence of innumerable biographies" (Thomas Carlyle). If this is so, then Dr Carron's well-referenced work lends credence to the definition since more than half the entries in the index refer to people. However, there is another definition: "What experience and history teach is this, that people and governments never have learnt anything from history or acted on principles deduced from it" (Geo. W. Hegel).
Or, more concisely, it can be said that "history repeats itself". This has been amply demonstrated in Australia. Dr Carron's account of the struggles to establish government forestry in the six separate States makes interesting reading in itself, but is all the more remarkable when considered in the context of parallel experiences in other countries.
To understand the book fully, it would have helped the non-Australian reader to put things in perspective had additional information relevant to Australia been given, such as the occurrence of various deep economic crises; the particular fire problems faced "down under"; the fact that Australia is a gross importer of forest products; that Australia comprised (some would say comprises) "six States in search of a Nation"; that the constitution vests so much power (always jealously guarded) in the States that federal forestry has been made a poor relation.
Notwithstanding this, the author has produced a readable narrative which gives due credit, without being laudatory, to those who contributed to the development of forestry. On the other hand, by the sheer factuality of his reporting, the author makes plain his scorn for dilatory high-level committees and unconvinced politicians. People whose work thrusts them into positions of responsibility can take heart from reading the achievements and battles (sometimes campaigns) fought by Australian forestry leaders.
The book's most valuable contribution is its chronicling of the development of a number of different forestry organizations some 12 in all - and of the events that led to the establishment of each organization. The technocrat lurking in all foresters will appreciate the accounts, which appear from time to time throughout the book, of technical advances such as the planting of southern pines in tropical Queensland, and the South Australian measurements of growth and yield.
EUCALYPTS IN CANBERRA BOTANICAL GARDENS important Australian trees
Unasylva readers who are responsible for, or who care about, organizations and their development, will at least gain solace from a book which so dispassionately reports on history repeating itself. The book may even consolidate readers' convictions that ways can be found to influence the course of forestry development.
Readers will not, however, find many references to pre-European land management, recreational use of forests, trees on farms, appropriate forest industries or national forest policy, nor will they find answers as to why A$1.6 thousand million should be spent to arrest soil degradation in the island continent. These are, however indictments of the Australian forestry systems and the Australian society of yesteryear, not of the author.
Perhaps this report of the development of forestry in Australia would be more comprehensive were Dr Carron, together with a political science collaborator, to add a commentary on events since 1975. The forestry problems being faced in Australia today will undoubtedly be tomorrow's problems in so many other countries.
T. FearnsideTony Fearnside is Senior Operations Officer and Chief of the Asia and Pacific Desk, FAO Forestry Department, Rome
Agroforestry in Australia and New Zealand. Rowan Reid and Geoff Wilson. Victoria, NSW. Goddard and Dobson, 1985.223 pp. Paperback.
In Australia and New Zealand, agroforestry means primarily the combining of tree growing with the raising of sheep and cattle and that is what this book is about.
The principal author, Rowan Reid, is a graduate of the University of Melbourne with a master's degree in agroforestry Co-author Geoff Wilson is an agricultural journalist who has been vigorously reporting on and promoting the benefits of tree growing to farmers in the two countries since the early 1970s - in the days when agroforestry was more commonly known as "farm forestry".
One should begin the book by reading Chapter 10, "What Agroforestry Needs Now". In this final chapter the authors candidly sum up the difficulties that have been encountered in achieving more widespread acceptance of agroforestry. They note that "only a small group of innovative farmers in Australia and New Zealand are doing well with agroforestry techniques". They attribute this to several factors, including a lack of practical information reaching farmers; a lack of understanding by farmers of the full range of benefits to be derived from trees apart from eventual timber crops; and, a serious shortage of economic data on agroforestry.
They suggest that it may take a new generation of farmers and extensionists to make agroforestry a commonly accepted and practised technique by the year 2000. If this is so, the book should be a useful contribution to agroforestry in several respects.
It is a readable and well-presented handbook on the state of the art, filled with the kind of practical information that should appeal to the pragmatic and practical people who make their living as farmers. Using a journalistic approach, the authors have put together a compact compilation of information and experience garnered from research reports, extension bulletins, technical articles, conference papers and interviews, supplemented by their own ideals and experiences.
For example, the chapter on implementation discusses whole farm planning, what it is, how to do it and where to go for assistance. The chapter on tree species describes site and growth characteristics and agroforestry applications for pines (six species), poplars, eucalypts, acacias, and a variety of individual fodder, fruit and nut species.
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PER ANDERS RAGNHAGE, 1944-1986 Per Anders Ragnhage, a saw-milling expert who had served as a Forestry Officer in FAO's Forest Industries Division for more than four years, died suddenly at the age of 46 on 3 November 1986 in his home country, Sweden. Before joining FAO, Mr Ragnhage had worked through the Swedish International Development Agency as the production manager of a sawmill in Kitwe, Zambia. Prior to that, he spent eight years working for three different sawmills in Sweden, advancing from building manager to production manager and then to general manager. At FAO, two of his special projects included coconut wood utilization in the Caribbean and mobile saw-doctoring units in Bangladesh. Mr Ragnhage, who held a pilot's license and was an avid golfer and water-skier, received a Diploma Engineer from the Högre Tekniska Läroverket in Borås, Sweden, in 1961. He is survived by his wife, Britt-Mari, and by three children, Pernilla (23), Jonas (20) and Pontus (17). He was a widely respected colleague and will be greatly missed at FAO. |
Of particular interest are the ten case-studies of farmers engaged in agroforestry, which lend a strong element of authenticity to the book. The tree farmers profiled represent a variety of practices: beef and timber; shelterbelts and sheep; tree fodder with wheat and sheep; fuelwood; beef and sheep; honey locust with sheep, etc.
The total range of tree management activities is also briefly covered, from seed orchards to planting, silviculture and marketing. Numerous references are provided where more detailed information can be obtained.
Information sources are frequently quoted by name, and the text is liberally supplemented with black-and-white photographs and other illustrations.
The book will also be a useful tool for the agriculture and forestry extension officers who work with sheep and cattle farmers. For the extensionist it is a source book on agroforestry/farm forestry as applied in New Zealand and Australia specifically and consequently deserves a place in the field kit of any agriculture or forestry extension agent.
One of the strengths of the book is that it points out the problems of agroforestry as well as the benefits, and the failures as well as the successes; what is not known as well as what is. Unfortunately, its weakest chapter is on the economics of agroforestry. The section is short, it lacks detailed economic analysis and fails to make a strong economic case for agroforestry in Australia and New Zealand.
The authors acknowledge this in their summation, noting that "until farmers can be shown how to make satisfactory returns out of tree farms, progress in agroforestry and any other farm tree planting will be painfully slow".
What it will take to accomplish this, they suggest, is more economic research, coupled with increased training and extension in agroforestry to generate a ground swell of activity that will be noticed by the bureaucrats and politicians who establish agricultural policy.
After all, in New Zealand and Australia, as elsewhere, it is still the farmers who must make the decision to grow trees, based on solid technical and economic information from the forest and agriculture researchers and extensionists.
R. PardoRichard Pardo is a Forestry Officer (Institutions) in the FAO Forestry Department, Rome
Forest trees of Australia. D.J. Boland, M.I.H. Brooker, G M. Chippendale, N. Hall. B.P.M. Hyland, R.D. Johnston. D.A. Kleining and J.D. Turner. Thomas Nelson Australia and CSIRO. 1984. xiii + 687 pp. hardback. 60 colour plates. ISBN 0 17 006264 3. Price: A$39.95.
This book is the fourth edition of Forest trees of Australia, an extensive guide to 223 Australian trees selected for their importance to the environment and to the timber industry. The main species from all the Australian States are included; 137, or 61 percent, of the trees discussed are eucalypts. For this fourth edition, a completely new section on species with new colour photographs, colour plates and maps has been prepared.
The first 35 pages of text are devoted to a general account of the evolution, variation and adaptation of Australian tree species. A description is given of the important tree families and the factors controlling the present-day distribution of trees in the landscape. The Australian climate is described in a series of maps giving information on temperature, radiation, rainfall, evaporation and the number of days without frost.
Species descriptions are grouped into gymnosperms, monocotyledons and dicotyledons. Useful introductory sections are given for major genera such as Acacia, Banksia, Casuarina, Eucalyptus and Melaleuca. Each tree description is given in a basic two-page format, with text and distribution map on the left and a composite set of black-and-white photographs on the right.
Think trees, grow trees. Canberra. Australian Government Publishing Service. 1985. 200 pp. ISBN 0 644 03736 9 hard cover; ISBN 0 644 04234 6 paperback. Price: A$24 hard cover; A$19.95 paperback, including surface mail and packing.
Think trees, grow trees was originally the title of a series of lectures presented in Canberra and arranged by the Institute of Foresters of Australia. Later, the Government's National Tree Programme provided funds for the lecture materials to be put together in this 200-page book characterized by a straightforward writing style, 75 excellent photographs and a high quality of production.
The book is for members of the general public who are interested in growing trees; it also reflects current Australian concern about trees and forests and will be useful to all foresters who talk to other people about trees.
There are 14 chapters, arranged in two main parts: "Think trees", dealing with trees in the environment and "Grow trees", about growing trees for various purposes. These are followed by an epilogue and an appendix on how to raise eucalypt seed-lings.
Nowadays it seems that trees and the environment are too vast a topic to be left to foresters alone: the 17 authors include a farmer, a senior park ranger, a pathologist, a fire expert, an arboriculturist and a soil scientist as well as a number of leading Australian foresters.
Think trees, grow trees is available from the Australian Government Publishing Service whose mail order sales (and trade sales manager) can be reached through GPO Box 84. Canberra, ACT 2601, Australia.
T. Fearnside
