All those people...
and signs of stress on the world's principal biological systems - fisheries, forests, grasslands, croplands
United Nations primer on desertification
Trees for dry lands
A basic pulp and paper text
Primer for wood preservation
The twenty-ninth day, by L.R. Brown. W.W. Norton and Co., New York, 1978. 363 p.
The population of the world is estimated at more than four thousand million. It took some two million years for human numbers to reach one thousand million; the second thousand million took a hundred years, the third was accomplished in 30 years, and the fourth thousand million made it in only 11 years. This book is about what that means in relation to food, energy and income.
United Nations projections show world population continuing to grow until it reaches 10 to 16 thousand million but the author does not believe that this is realistic. He sees signs of stress on the world's principal biological systems - fisheries, forests, grasslands and croplands - and claims that in many places these systems already have reached the breaking point. To expect these to withstand a tripling or quadrupling of population pressures, says Brown, defies ecological reality.
The total world fish catch is 70 million tons annually, 60 marine and 10 inland. It is pointed out that the productivity of marine fisheries in some parts of the world is now falling as the catch exceeds the regenerative capacity of the various species of fish. But as the world fish catch levels off or drops, pressures on land-based biological systems are intensifying.
The forests provide lumber, a universal building material, firewood, a principal source of energy for close to one third of humanity inhabiting mostly developing countries, and raw material for paper and a host of other products. These forests have proved to be one of humanity's most valuable economic resources and consequently one of the most heavily exploited. But in many parts of the world, especially in the tropics, they are shrinking rapidly before the onslaughts of firewood-gatherers, land-hungry farmers, and industrial timber interests. Almost every country undergoing rapid population growth is fast being depleted of forests, reminding one of Chateaubriand's remark, "The forest came before civilization and the deserts after it".
A STREET SCENE IN BANGLADESH population affects everything
The grasslands support dairy cattle, buffalo, camels, goats and sheep which supply most of the world's meat and milk, sustain draught animals that till a third of the world's croplands and provide a number of raw materials for industrial use. Together, population growth and affluence and consequent increasing demand for protein and other animal products are taxing the grassland where overgrazing is already commonplace.
The croplands occupy one tenth of earth's land surface. But the growth in demand for food and other products of the tilled fields is expanding at a record pace subjecting croplands to heavy pressure. Fallow cycles are everywhere shortening, and farmers seeking land are moving up on to steep slopes and into soils of marginal quality and low fertility where they should not be. Brown does not forget to point out yet another aggravating burden - that of excessive waste caused by burning of fossil fuels, discharge of industrial waste and use of agricultural chemicals, all overtaxing the earth's natural function of waste absorption.
The author makes the point that as ecological stresses increase they quickly turn into economic ones such as inflation, capital scarcity and unemployment. It is noted that historically inflation was a localized phenomenon experienced by individual countries from time to time, but during the 1970s it assumed global dimensions; Brown has an interesting analysis of this development. Concerning investment capital, he notes that diminishing returns, typical of the food and energy sectors, make capital formation more difficult and that capital shortages are spreading. As to unemployment, the global labour force is growing at a record rate while the scope for creating new jobs is limited. New land for settlement has become scarce or concentrated in few hands, opportunities for rapid economic growth are subsiding and the expanding number of the jobless is becoming a serious burden in too many countries of the world.
In the closing part of the book the author suggests measures to meet this avalanche of problems. Political will and human ingenuity are needed above all.
Adjustments in consumption patterns, shifts to renewable energy resources and rural reforms, such as redistribution of land so that those dependent upon if will own it and have the incentive to improve it, are some of the measures suggested to overcome food shortages and to stimulate production. Concerning declining oil reserves, Brown calls for crash programmes in energy conservation and a broadly based global effort to develop the entire range of renewable energy resources.
The author is adept at putting forth global issues, particularly in his analysis of the four major biological systems on which humanity depends for food and industrial raw materials. But he is definitely stronger on the horrors than on the ways to dispel them.
P. ARGAL
Desertification: its causes and consequences. Compiled and edited by the Secretariat of the United Nations Conference on Desertification, Nairobi Kenya, Pergamon Press, Oxford, New York, Toronto, Sydney, Paris, Frankfurt, 1977. 448 p.
Desertification has intensified in recent decades throughout the world. It is now threatening the future of over 600 million people inhabiting arid and semi-arid lands that cover more than a third of the earth's land area.
This volume, comprising four global reviews and an overview, was prepared as a background document for the delegates to the United Nations Conference on Desertification held in Nairobi from 29 August to 9 September 1977 and examines the interrelationships of desertification with climate, ecological change, population, society and technology.
The conference found its origin in the awareness of the Sahel drought disaster, the long drought along the southern margin of the Sahara, between 1969 and 1973. Its tragic effect not only generated an international relief effort to distressed countries, but also attracted attention throughout the world to the chronic problem of human survival and development on desert margins and led to a call for countermeasures to the spread of desertification. The conference brought together the representatives of about 100 countries and many international and non-governmental organizations.
The volume opens with an overview that synthesizes the four global reviews, which are sectoral and technical in character, and not only elaborate the causes and consequences of desertification but also provide scientific justification for its cure.
A scholarly study by F. Kenneth Hare, "Climate and desertification," looks into the relationship of desertification to climate. It points out that the large-scale climate of the earth is governed mainly by global distribution of radiative energy, by the inequities of land and sea and by the general circulation of the atmosphere and oceans. Discussing the drier climates, which occur at sea as well as on land, the author states that they are caused largely by atmospheric subsidence which on an unequally heated earth always occurs in subtropical latitudes, between latitudes 15 and 30 degrees north and south of the equator. Therefore, deserts must always have existed in the earth's subtropical zones. The variability of dry climate is reviewed on both long and short time-scales. The recent droughts in the Sahel and elsewhere are not con sidered as unprecedented, prolonged Desertification lasting a decade or more being common in the records, a phenomenon to be anticipated at long intervals. The author is of the view that the world climate appears to have remained fairly constant during the past two thousand years or more. As to the role of man in influencing climate changes, it is stated that major shifts of climate are related to global changes in the general circulation of atmosphere and its oceanic interactions and are beyond the influence of man, but deteriorating surface microclimates and increases in albedo (the latter causing further decrease in rainfall) directly flow from overstocking or unwise cultivation of dry-land surfaces during periods of drought. For amelioration of present conditions better land use (leading to improved microclimates), precipitation enhancement by artificial means in the more humid areas of dry regions, and realistic use of existing climatic statistics for decision-making are suggested.
The contribution by A. Warren and J.K. Maizels, "Ecological change and desertification," deals with land-use practices in dry ecosystems and their impact on environment. Evidence for Desertification (sustained decline in biological productivity of a dry area accompanying certain kinds of environmental change, both natural and induced), which is diffuse and difficult to quantify, is reviewed. Patterns of production and strategies of resilience are discussed.
Land-use practices such as pastoralism or herding of livestocks, rainfed cropping, irrigation agriculture, land clearance for industry or housing, wood collection for fuel and construction, and the changes induced by them are discussed, pointing out that no land-use system has been so self-regulating or so perfectly adopted to arid conditions that it has incurred no cost to the environment. For example, in irrigated agriculture, particularly where drainage is poor and leaching inadequate, waterlogging often causes salts and alkali to infect soils, adversely affecting plant growth; clearing land for industry and especially for mining increases areas of bare ground which entails erosion, surrounding streams get choked with sediment and toxic wastes are added to the environment. Intensive gathering of firewood - the main source of energy for cooking among most dry-land populations - leads to destruction of trees and shrubs, exposing soil to wind and water erosion. Desertification fact, accompanied all land-use systems (disturbing the ecological balance), its effects being less destructive in the past when people were few and land less densely occupied. Existing methods of evaluating the extent of desertification are reviewed and a simplified method of rapid assessment suggested. For successful exploitation of dry ecosystems, strategies based on ecological principles are sugested.
The global review contributed by R.W. Kates, D.L. Johnson and K.J. Haring, "Population, society and desertification," states that desertification is a complex problem and is the product of interaction between social changes, climate and ecosystems.
Drought can lead to desertification by decreasing vegetative production and delaying its recovery rates. Exceptionally wet periods may also promote desertification by encouraging extension of agriculture and pastoral settlement into areas generally too dry to utilize and by encouraging an intensified pattern of land use.
Discussing the social causes of desertification, the most important processes of social change which serve as contributors to desertification are those usually associated with, (i) rapid change in number of people utilizing and dependent on resources of dry lands, (ii) differential access to technology, (iii) the political structure of regions and countries, (iv) world integration and specialization, and vulnerability of traditional livelihood practices to external market forces. Discussing the association of political structures with desertification, the authors point out that both positive and negative consequences flow from government actions. For example, the security, technology, organization and support provided by government to irrigation and run-off systems helps to increase productivity, but often spreads salination, or diverting former grazing land to agricultural use adds to desertification pressures on adjacent rangelands.
The volume is concluded by a review from M.A. Garduno, "Technology and desertification." It describes, evaluates and discusses appropriate technologies to combat desertification in different land-use systems for the purpose of improving productivity by preventive measures, halting and reversing desertification by corrective measures, and for reclaiming desertified areas. Desertification can be remedied with the help of technology now available, says Garduno, but the results should be worth the cost and the selected technology should be appropriate.
This well-produced volume will probably be a standard source on causes and consequences of desertification for years to come.
P. ARGAL
Reforestation in arid lands, by Fred R. Weber. Frederick J. Holman (illustrator) and Virginia C Palmer (editor), 1977. Action/Place Corps Program & Training Journal Manual Series No. 5. VITA Publications Manual Series No. 37E, 248 pages. Price: $6.50.
This manual has been prepared as a practical aid to grass-roots action in reforestation and revegetation in arid zones. Though its main references are to the West African areas of summer rainfall, it contains much that is useful to workers in different climatic zones. Textbooks usually contain hopeful statements about the long-term view that must be taken in land-use planning in arid zones and practical manuals tend to concentrate on techniques without regard to the overview. This book contains both approaches, and its second chapter is a good summary of considerations in planning. The illustrations of Frederick Holman are a useful addition, especially as those who use the book are not likely to have libraries nearby. There is a short chapter on the importance of soils, followed by one on the choice of species. This is especially oriented toward West Africa, and it is here that the title appears to promise more than the book contains: "Reforestation in the dry zones of West Africa" would have been more accurate, and the book would certainly not suffer from this change of title. A failing of the book is its lack of proper explanation about various species. For instance the author refers to Eucalyptus noting that it is not native to Africa (but failing to note that Neem, Azadirachta indica, is not native either), without giving species. Of the total of over 600 species of Eucalyptus, about 10-20 may be suitable for dry zones, and these deserve listing more fully, if planting disasters are to be avoided.
There is a section dealing with the importance of project planning, and Appendix D provides a very simple checklist of points to be considered in drawing up a project. Quite rightly, the author points out the importance of including vital information for funding organizations to consider a project.
The bulk of the book is taken up with 128 pages of species identifications, with drawings reproduced from a number of standard botanical works. The drawings vary in quality but are generally good, and the species are almost all West African in origin For many of them West African local names are given in several languages, which should be very valuable to field workers in the Sahel. Eucalyptus camaldulensis is the only eucalypt mentioned - it is certainly the most important, but by no means the only one for dry zones; E. tereticornis, E. citriodora, E. occidentalis, E. microtheca and E. urophylla, among others, should be mentioned. This is followed by vegetation and climatic maps of West Africa, and a brief profile of vegetation types. Research stations and contacts and a brief bibliography complete the book.
The price of $6.50 seems high for this publication, though presumably many of the people it aims to reach obtain copies free of charge. It is heavily weighted toward botanical identification from other published sources, but is generally sound in its recommendations. It should not be used as a sole guide however, even in West Africa; there are several important titles omitted from its list of references which would be of value to workers in dry-zone forestry. But it is a helpful manual, and, if it encourages tree planting in the Sahel, will have served a most useful purpose.
P.J. WOOD
Appropriate Technology, London
Pulp technology and treatment for paper, by James d'A. Clark. Miller Freeman Publications Inc., San Francisco California, 752 pages, illustrated, 1978. Price: US$65.
James d'A. Clark, TAPPI Gold Medal winner in 1963 and chairman of the TAPPI Standards Committee for seven years, has written this book for both students and seasoned veterans of the industry. The first 10 chapters review the basic principles of pulp technology from the point of view of chemistry, colloid chemistry, physics, mechanics, carbohydrates, and the nature of fibres. Subsequent chapters make use of these principles to broaden the reader's papermaking horizon, presenting many original and practical tests, procedures, and instruments.
The author conveys numerous insights into fibre technology by combining salient aspects of his own and other investigators' recent work with advanced concepts of surface chemistry and the details of submicroscopic fibre structure revealed by the scanning electron microscope. Along the way, he unveils precise, new methods for tasks such as characterizing the performance of refiners and measuring fibre cohesiveness. He also gives a practical, low-cost and positive method for testing wet-web strength quickly and efficiently. The book concludes with time-saving suggestions for the acquisition and filing of scientific data.
The book contains 752 pages in 36 chapters and more than 400 photos, tables, and figures. It can be used as a comprehensive textbook for beginners or as a basic reference book.
Wood preservation, by B.A. Richardson. The Construction Press Ltd., Lancaster, England, 1978. 238 p.
This book provides a fairly comprehensive account of wood preservation, a subject by no means new, but which has received increasing attention with a growing consciousness throughout the world of the need for more efficient utilization and protection of natural resources of all kinds.
The material is presented in five chapters and three appendixes. The book opens with a brief history of the various preservation systems adopted from ancient times to the present day, and is followed by an account of many different kinds of fungal and insect attacks to which wood is subject. The succeeding two chapters deal with preservative techniques in current use, and chemicals used as preservatives. The concluding chapter is devoted to discussion of economically realistic preservation practices.
Tracing the history of various preservation systems, adopted from early times to the present day, there are references to use of bitumen by ancient Egyptians (2000 B.C.) for preserving coffins and the use of cedar oil by Romans to protect wood from decay. The author makes the point that interest in wood preservation received stimulus from the frantic search for suitable preservatives to protect ships from marine borers and decay, particularly by the British Navy. It gained further during the second quarter of the 19th century, with widespread expansion of railways and use of wooden sleepers (that decayed rapidly) to support the rails.
In Chapter II the author discusses the causes of degradation of wood and describes the agents that are responsible for it.
There is a detailed discussion of the conditions necessary for development of fungi and destroying bacteria, and on the effect of decay on wood properties. Insects capable of seriously damaging wood, such as termites, bark-borers, powder-post beetles, and marine borers, are also discussed. There is a short discussion of changes in moisture content of wood and its influence on wood properties.
In Chapter III the author goes at some length into modern processes employed to protect wood from decay and insect attack, which are classified roughly as either pressure or non-pressure processes.
The more widely recognized non-pressure processes for treating wood involve brushing or spraying, dipping, soaking, steeping, diffusion and hot and cold baths; and there is a brief description of each of these processes Miscellaneous non-pressure treatments such as charring, applying preservative in bored holes, setting timber in stones or concrete, and taking structural precautions to ensure that wood remains dry are briefly touched upon. For example, it is pointed out that immersion treatments are most suitable for applying low viscosity organic solvent preservatives to dry wood (preservative penetration and loading are good provided adequate time is available), but are unsuitable for use with rapid fixing preservatives.
The pressure processes of wood preservation in which wood is placed in a treatment cylinder or retort and impregnated with preservatives under pressure are explored at more length.
The author acquaints the reader with the general procedure of the full-cell process (such as the Bethell process) and the empty-cell process (such as the Lowry and Rueping processes).
Discussing the capability of wood to withstand fire and excessive heat, it is pointed out that, even though wood is combustible, fire resistance is best achieved in a building by using wood of adequate thickness as well as by fire retardant treatment. Fire retardant chemical treatment is briefly discussed.
This is a practical book and will be of interest and value to all those interested in becoming acquainted with wood preservation. The lack of bibliography and references to specific statements in the text has, however, impaired the utility of the book.
P. ARGAL
