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Man and the biosphere — The framework of an international programme
Geoforum
411970
91
Reports
Man and the Biosphere - The Framework of an International Programme Walther MANSHARD,
Paris
In his editorial, as well as in the introductory methodological essay, H. UHLIG (Geoforum l/70) is concerned with the complex world-wide man-earth ecosystem (BERRY, 1964). In this connection, reference is made to the proposed UNESCO programme on “Man and the Biosphere”. Since the writer of this contribution (a co-chairman of the Geographical Institute at the University of Giessen, Germany) is now in charge of the Department of Environmental Sciences and Natural Resources Research at UNESCO, the editors of “Geoforum” requested him to submit a brief outline of the proposed programme for the geographical public. (For a more detailed account cf. UNESCO-C/78, from which most of this paper was taken.) The biosphere is that thin layer of soil, air and water that covers the surface of the Earth and within which all life exists. Within this layer a complex series of processes and interactions has been taking place which has led to the emergence of modern man. The role of man, however, in these processes and interactions has been small until very recently. But in the last century, and more particularly in the last decades, the impact of man on the biosphere has grown at an exponential rate. It has become global in scope and has reached the point where the entire system which has made life - and particularly human life - possible, is basically affected. As a result of these changes, new cycles of matter and flows of energy are being created that are ever increasing the realm of actions for every man. At the same time, however, the past cycles of nature are being progressively disrupted by the growing pressures of population on the land, by the spread of urbanization and industrialization, by mobility of people, the transport of resources and products, the accelerated use of energy from fossil fuels, and the increase and transport of the waste products of human living and activities. In this process, not only has man triggered off a series of new interactions in the physical and biological world, but the effects of these interactions on man himself have been manifold. Many of these interactions have brought consequences which have enriched human life, particularly regarding physical and material welfare, and which have permitted a rapid increase in human populations. But at the same time, and largely as a result of this enrichment and increase, they have contributed to an ever-expanding deterioration of the environment, leading to a situation in which the future of many forms of life and of man’s well-being are endangered. A substantial amount of research work has already been conducted in many countries to study the processes - both natural and manaffected - which are taking place in the biosphere. The International Biological Programme for instance has played a significant role * Prof. Dr. Walther MANSHARD, Director, Department of Environmental Sciences, UNESCO, Place de Fontenoy, Paris 7e, France.
in this connection and is developing basic methodologies which could be used on a world-wide basis. Conclusions from research and experiments conducted by many national or international organizations can be translated into action programmes. Technologies have been developed in several countries to remedy certain harmful consequences of environmental problems such as air and water pollution and these technologies could be more widely applied. Thus there is a considerable background on which to base environmental management. What has been described as a growing crisis of the human environment will compel most countries to increase significantly in the coming years their practical programmes of action - be it of an administrative, legislative, foal, economic or technical nature to alleviate the effects of problems arising from pollution, unsatisfactory land use and unplanned urbanization. The recognition of this situation has led the UN General Assembly to convene, in Stockholm in 1972, a Conference on the Human Environment which is primarily intended to study such problems and to pre mote appropriate preventive or corrective actions and programmes by public authorities at the local, national, regional or intemational level The growing magnitude and complexity of these actions, their diversity under various ecological and so&-economic conditions and their costs and consequences for the community, require that they be based at all times on the most reliable scientific infonnation. The fact is that such reliable information is still lacking on many fundamental environmental issues and in many regions. It is not yet known, for instance, what is the porential sustained productivity of the main ecosystems of the world, or what are the scientific bases of wise ecosystem manipulation and environmental management particularly under tropical conditions. There is there fore a need for a long-term scientific programme on a world-wide basis that will increase understanding of the functioning and strut tore of the biosphere, of both its natural and managed ecosystems, and thus increase man’s ability to predict the consequences of today’s actions on tomorrow’s world, permitting mankind to chose to act with a view to its long-term best interests. All systems of nature are becoming more open and interrelated and subtle changes of fundamental importance are taking place in these systems It is imperative to measure and to moniror these changes and to be able to forecast better their consequences, particularly for those changes that are caused by man or whose rates are accelerated by human actions. For example, the experience of recent decades has shown that the production of energy has been doubling about every ten years from the use of hydroelectric power, fossil fuels, and nuclear energy. It is not presently known what the consequences of such release of heat and wastes may be for man and the biosphere if this rate were to continue for a century. Nor is it known whether indiscerned changes in soil properties and composition may affect the basic capacity of soils for future produc tion. Nor indeed is it known what the consequences would be of the predicted increase in human populations, or even if such an increase could be sustained. Even if science and technology could meet the needs of such population numbers, little is known on whether society can be organized to meet the requirements of this number and at what level of living it can be accomplished. What
92
will human habitats be like, and will they be pleasing to man? The question of quality of the human environment needs equal consideration, in such calculations with that of quantity of resources and production, if man’s life on the planet is to remain satisfactory. There is need, therefore, for a programme that will provide a scientific basis for environmental planning on a global scale, having environmental quality as a central concern, and keeping quality criteria under systematic review. History has shown that slngkpurpose or narrowly-focused ap proaches to environmental problems and environmental manage ment have often brought adverse effects. These approaches have, time after time, led to disruption of ecological systems to the end that many are now degraded while others are becoming increasingly unsuited to man’s use or occupancy. There is a need therefore for a programme of an interdisciplinary nature, invoking specialized fields of natural and social sciences, where the central approach will be ecological. Ecological systems do not recognti_e the frontiers of states. Human decisions and actions that may be provincial in origin have national and international consequences. Only through international co-ordinated research efforts can these interrelationships be clearly understood. Each nation, large or small, rich or poor, with many or few scientists, will find that it can and must contribute to the problems that concern all mankind - each according to its ability. The programme that is required to observe and to understand the interactions between man and the biosphere, is indispensably an international co-operative programme of global scope having the strongest possible support from governments. In conclusion, while there is already available a substantial amount of knowledge on which immediate actions can be based, and while there are, at the international level, a number of research projects and programmes which are of direct value to the study of the relationship between man and the biosphere, the present insufficient level of monitoring facilities and of authoritative ecological knowledge, as well as the vital importance and magnitude of the issues at stake, demand the initiation of a vigorous intergovernmental and interdisciplinary effort for observation and research. At the same time, since manpower in the disciplines concerned is scarce and since no permanent achievements in research or in practical action can be obtained without a major reorientation in environmental and ecological education, there is a need to support the international research programme with an equally strong educational component. Brief Outlines of the Programme The general objective of the programme on “Man and the Biosphere” is: “To develop the scientific basis for the rational use and conservation of the resources of the biosphere and for the improvement of the global relationship between man and the environment, and thus increase man’s ability to manage efficiently the natural resources of the biosphere and to predict the consequences of today’s actions on tomorrow’s world.” With this general objective in mind, the programme is intended more specifically: a) To identify and to assess the effects of man’s actions upon the biosphere and conversely to those of the biosphere on man. b) To analyse and compare the functioning of natural, modified and managed ecosystems on a world-wide scale. c) To develop ways and means to monitor and measure quantitative and qualitative changes in the environment in order to establish scientific criteria to serve as a basis for rational management of natural resources and for establishment of standards of environmental quality.
Geoforum
411970
d) To establish agreed, and where appropriate, standardised methodologies, for the acquisition and processing of data, and to facilitate the exchange and transfer of available and newlydeveloped knowledge on the analysis and treatment of environmental problems, in order to help bring about greater global coherence of environmental research.
e) To promote the development and application of simulation and other approaches which will facilitate the prediction of likely future trends, permitting mankind to direct its actions with a view to its long-term best interests. To develop environmental study material for educational curricula at all levels, to promote technical training and to stimulate global awareness of environmental problems through public and other information media. For convenience the research themes envisaged are presented under four headings: I. Projects related to the natural environment, meaning environments that are little modi(Nos. 1-11) fled by man. II. Projects related to the rural environment, meaning environments used primarily for agriculture, forestry, or other uses that do not involve major technological transfor(Nos. 12-21) mations of the landscape. III. Projects related to environments affected by urbanization or subject to major technological modification by urban-industrial (Nos. 22-27) society. Projects concerned with pollution or related IV. (Nos. 28-31) phenomena, as they affect the biosphere. The 3 1 possible research themes which are only intended to provide the outlines of the future programme are as follows: 1. 2.
Definition, classification and mapping of ecosystems; Mapping of world vegetation.
3.
Comparative studies of soils categories, based on world soil map.
4.
Analysis of ecosystems, their structure and functioning, energy flow and productivity. Distribution and cycling of important bio-geochemical elements.
5. 6. 7. 8.
Photosynthesis, growth and primary productivity. Plant-Soil-Water relationships. Baseline studies of undisturbed ecosystems in comparison with modified ecosystems, including identification of biological indicators.
9.
Role of consumers in ecosystem dynamics. Co-ordinated world-wide network of national parks, biological reserves and other protected areas. Conservation of wild plant and animal species. Comparative analysis of agricultural, managed forest and natural communities as total ecosystems. Research and studies in agricultural bioclimatology. Transformation of vegetation in relation to productivity, hydrology and stability of ecosystems. Role of introduced species in ecosystems’ functioning and stability.
10. 11. 12. 13. 14. 15. 16. 17. 18.
Optimum use and long-term effects on production and on ecosystems of organic and inorganic fertilizers. Use and role of fire in ecosystems modification. Ecology and performance of wild and domesticated grazing and browsing animals.
Geoforum
4/1970
93
19.
Studies on the ecology of decomposer organisms and on the effects of man-made changes in the environments on the recycling capacity of soil organisms.
tions, however. it can also serve as a pattern for smaller urban centres. After this exercise similar patterns for typical rural settlements could easily be worked out by teachers and students.
20. 21.
Ecology and rational use of island ecosystems. Human adaptation, land use and environmental relationships in extreme environments, including deserts, high mountains, polar and subpolar regions.
22.
Impact of urban ecosystems on the structure and functioning of the biosphere. Effects on man and his environment of major engineering projects, river-basin developments, pest and disease eradication schemes and other major modifications of ecosystems. Effects on man and his environment of recreation, tourism and related developments.
For didactic reasons and to facilitate memorization the order chosen is strictly alphabetical For reasons of simplicity, I have left out of this classification the important communication links. some of which are included in the sketch ; for example. the main railway station, which is usually not quite centrally situated because of its fairly late introduction in the 19th and 20th centuries ; and the airport. which for obvious reasons is generally between S-10 miles outside the city. Inland water-ways. river ports. harbours etc. can be added to suit local conditions (Fig. 1).
23.
24. 25.
Ecology and rational use of estuarine regions and the coastal zone.
26.
Environmental and socioeconomic criteria influencing optimum use of vaious biotic regions as a basis for urban, rural and regional planning.
27.
Perception and definition of the ecological and cultural bases for environmental quality.
28.
Inventories and toxicology of environmental pollutants.
29.
Monitoring of global changes in pollutant levels. Investigations of man’s long-term influence on the heat balance of the Earth.
30. 31.
Systematic observations of the factors and processes leading to eutrophication and chemical pollution of fresh waters. Within the proposed International Coordinating Council, scientists from twenty-five Member States as well as representatives of other United Nations Agencies and scientific unions, will advise on a more detailed and specialized programme, setting up priorities. The first meeting of this Council will take place in 1971 so that the programme, assisted by workinggroups and expert panels, may become operational in 1972.
Fig. 1 A Simple Teaching Model Explaining the Spatial Differentiation W. MANSHARD,
of Urban Functions’)
Schematical pattern of functional areas in a typical town (of about 50,000 inhabitants). The scale of A, B, C as compared with D has been exaggerated
Paris
9 In as of to
my experience, the First Year student in a university as well the Sixth Form student, finds it much easier to study the site towns. or to compare their size ln area and population, than grasp the functional pattern of urban centres.
Though the student often has a detailed knowledge of the town ln which he has lived for many years, it is difficult for him to recognlse the functions within his town and to deduce a spatial distribution of typical urban services and amenities. To break through this “barrier” of “not seeing the wood for the trees”, I have in past years used the simple teaching device set out below. After understanding this generalized schematic pattern. students mostly fiid it quite easy to adapt it to their own town. It may also help them to read with more understanding the wldespread geographical and sociological literature on towns. This model may, in my opinion. be applied to any fullyfledged town or city of over 50.000 inhabitants. With suitable modiflca-
A first account of this model with special reference to Ghanaian towns (especially Accra and Kumasi) appeared in the Bulletin of the Ghana Geographical Association VoL 5 1960/l pp. 2124. (The author is indebted to the late Miss F. C. MILLER, University of Southampton, England, for the initial idea.) This simplified teaching model follows the pattern of concentric rings as conceived by BURGESS for European and American cities. In reality, the structure of most African cities is much more complex because of the development of urban areas inhabited by different ethnic groups. Besides the indigenous population. there are the migrants and foreign or “colonial” elements like Europeans, Indians or Lebanese. Often the commercial centre develops where these urban areas touch each other. Also, the market has a special functional role in African townships. (cf; discussion remarks: A. L. MABOGUNJE. International Symposium on Urban Growth in Black Africa and Madagascar, Bordeaux 1970).
411970
91
Reports
Man and the Biosphere - The Framework of an International Programme Walther MANSHARD,
Paris
In his editorial, as well as in the introductory methodological essay, H. UHLIG (Geoforum l/70) is concerned with the complex world-wide man-earth ecosystem (BERRY, 1964). In this connection, reference is made to the proposed UNESCO programme on “Man and the Biosphere”. Since the writer of this contribution (a co-chairman of the Geographical Institute at the University of Giessen, Germany) is now in charge of the Department of Environmental Sciences and Natural Resources Research at UNESCO, the editors of “Geoforum” requested him to submit a brief outline of the proposed programme for the geographical public. (For a more detailed account cf. UNESCO-C/78, from which most of this paper was taken.) The biosphere is that thin layer of soil, air and water that covers the surface of the Earth and within which all life exists. Within this layer a complex series of processes and interactions has been taking place which has led to the emergence of modern man. The role of man, however, in these processes and interactions has been small until very recently. But in the last century, and more particularly in the last decades, the impact of man on the biosphere has grown at an exponential rate. It has become global in scope and has reached the point where the entire system which has made life - and particularly human life - possible, is basically affected. As a result of these changes, new cycles of matter and flows of energy are being created that are ever increasing the realm of actions for every man. At the same time, however, the past cycles of nature are being progressively disrupted by the growing pressures of population on the land, by the spread of urbanization and industrialization, by mobility of people, the transport of resources and products, the accelerated use of energy from fossil fuels, and the increase and transport of the waste products of human living and activities. In this process, not only has man triggered off a series of new interactions in the physical and biological world, but the effects of these interactions on man himself have been manifold. Many of these interactions have brought consequences which have enriched human life, particularly regarding physical and material welfare, and which have permitted a rapid increase in human populations. But at the same time, and largely as a result of this enrichment and increase, they have contributed to an ever-expanding deterioration of the environment, leading to a situation in which the future of many forms of life and of man’s well-being are endangered. A substantial amount of research work has already been conducted in many countries to study the processes - both natural and manaffected - which are taking place in the biosphere. The International Biological Programme for instance has played a significant role * Prof. Dr. Walther MANSHARD, Director, Department of Environmental Sciences, UNESCO, Place de Fontenoy, Paris 7e, France.
in this connection and is developing basic methodologies which could be used on a world-wide basis. Conclusions from research and experiments conducted by many national or international organizations can be translated into action programmes. Technologies have been developed in several countries to remedy certain harmful consequences of environmental problems such as air and water pollution and these technologies could be more widely applied. Thus there is a considerable background on which to base environmental management. What has been described as a growing crisis of the human environment will compel most countries to increase significantly in the coming years their practical programmes of action - be it of an administrative, legislative, foal, economic or technical nature to alleviate the effects of problems arising from pollution, unsatisfactory land use and unplanned urbanization. The recognition of this situation has led the UN General Assembly to convene, in Stockholm in 1972, a Conference on the Human Environment which is primarily intended to study such problems and to pre mote appropriate preventive or corrective actions and programmes by public authorities at the local, national, regional or intemational level The growing magnitude and complexity of these actions, their diversity under various ecological and so&-economic conditions and their costs and consequences for the community, require that they be based at all times on the most reliable scientific infonnation. The fact is that such reliable information is still lacking on many fundamental environmental issues and in many regions. It is not yet known, for instance, what is the porential sustained productivity of the main ecosystems of the world, or what are the scientific bases of wise ecosystem manipulation and environmental management particularly under tropical conditions. There is there fore a need for a long-term scientific programme on a world-wide basis that will increase understanding of the functioning and strut tore of the biosphere, of both its natural and managed ecosystems, and thus increase man’s ability to predict the consequences of today’s actions on tomorrow’s world, permitting mankind to chose to act with a view to its long-term best interests. All systems of nature are becoming more open and interrelated and subtle changes of fundamental importance are taking place in these systems It is imperative to measure and to moniror these changes and to be able to forecast better their consequences, particularly for those changes that are caused by man or whose rates are accelerated by human actions. For example, the experience of recent decades has shown that the production of energy has been doubling about every ten years from the use of hydroelectric power, fossil fuels, and nuclear energy. It is not presently known what the consequences of such release of heat and wastes may be for man and the biosphere if this rate were to continue for a century. Nor is it known whether indiscerned changes in soil properties and composition may affect the basic capacity of soils for future produc tion. Nor indeed is it known what the consequences would be of the predicted increase in human populations, or even if such an increase could be sustained. Even if science and technology could meet the needs of such population numbers, little is known on whether society can be organized to meet the requirements of this number and at what level of living it can be accomplished. What
92
will human habitats be like, and will they be pleasing to man? The question of quality of the human environment needs equal consideration, in such calculations with that of quantity of resources and production, if man’s life on the planet is to remain satisfactory. There is need, therefore, for a programme that will provide a scientific basis for environmental planning on a global scale, having environmental quality as a central concern, and keeping quality criteria under systematic review. History has shown that slngkpurpose or narrowly-focused ap proaches to environmental problems and environmental manage ment have often brought adverse effects. These approaches have, time after time, led to disruption of ecological systems to the end that many are now degraded while others are becoming increasingly unsuited to man’s use or occupancy. There is a need therefore for a programme of an interdisciplinary nature, invoking specialized fields of natural and social sciences, where the central approach will be ecological. Ecological systems do not recognti_e the frontiers of states. Human decisions and actions that may be provincial in origin have national and international consequences. Only through international co-ordinated research efforts can these interrelationships be clearly understood. Each nation, large or small, rich or poor, with many or few scientists, will find that it can and must contribute to the problems that concern all mankind - each according to its ability. The programme that is required to observe and to understand the interactions between man and the biosphere, is indispensably an international co-operative programme of global scope having the strongest possible support from governments. In conclusion, while there is already available a substantial amount of knowledge on which immediate actions can be based, and while there are, at the international level, a number of research projects and programmes which are of direct value to the study of the relationship between man and the biosphere, the present insufficient level of monitoring facilities and of authoritative ecological knowledge, as well as the vital importance and magnitude of the issues at stake, demand the initiation of a vigorous intergovernmental and interdisciplinary effort for observation and research. At the same time, since manpower in the disciplines concerned is scarce and since no permanent achievements in research or in practical action can be obtained without a major reorientation in environmental and ecological education, there is a need to support the international research programme with an equally strong educational component. Brief Outlines of the Programme The general objective of the programme on “Man and the Biosphere” is: “To develop the scientific basis for the rational use and conservation of the resources of the biosphere and for the improvement of the global relationship between man and the environment, and thus increase man’s ability to manage efficiently the natural resources of the biosphere and to predict the consequences of today’s actions on tomorrow’s world.” With this general objective in mind, the programme is intended more specifically: a) To identify and to assess the effects of man’s actions upon the biosphere and conversely to those of the biosphere on man. b) To analyse and compare the functioning of natural, modified and managed ecosystems on a world-wide scale. c) To develop ways and means to monitor and measure quantitative and qualitative changes in the environment in order to establish scientific criteria to serve as a basis for rational management of natural resources and for establishment of standards of environmental quality.
Geoforum
411970
d) To establish agreed, and where appropriate, standardised methodologies, for the acquisition and processing of data, and to facilitate the exchange and transfer of available and newlydeveloped knowledge on the analysis and treatment of environmental problems, in order to help bring about greater global coherence of environmental research.
e) To promote the development and application of simulation and other approaches which will facilitate the prediction of likely future trends, permitting mankind to direct its actions with a view to its long-term best interests. To develop environmental study material for educational curricula at all levels, to promote technical training and to stimulate global awareness of environmental problems through public and other information media. For convenience the research themes envisaged are presented under four headings: I. Projects related to the natural environment, meaning environments that are little modi(Nos. 1-11) fled by man. II. Projects related to the rural environment, meaning environments used primarily for agriculture, forestry, or other uses that do not involve major technological transfor(Nos. 12-21) mations of the landscape. III. Projects related to environments affected by urbanization or subject to major technological modification by urban-industrial (Nos. 22-27) society. Projects concerned with pollution or related IV. (Nos. 28-31) phenomena, as they affect the biosphere. The 3 1 possible research themes which are only intended to provide the outlines of the future programme are as follows: 1. 2.
Definition, classification and mapping of ecosystems; Mapping of world vegetation.
3.
Comparative studies of soils categories, based on world soil map.
4.
Analysis of ecosystems, their structure and functioning, energy flow and productivity. Distribution and cycling of important bio-geochemical elements.
5. 6. 7. 8.
Photosynthesis, growth and primary productivity. Plant-Soil-Water relationships. Baseline studies of undisturbed ecosystems in comparison with modified ecosystems, including identification of biological indicators.
9.
Role of consumers in ecosystem dynamics. Co-ordinated world-wide network of national parks, biological reserves and other protected areas. Conservation of wild plant and animal species. Comparative analysis of agricultural, managed forest and natural communities as total ecosystems. Research and studies in agricultural bioclimatology. Transformation of vegetation in relation to productivity, hydrology and stability of ecosystems. Role of introduced species in ecosystems’ functioning and stability.
10. 11. 12. 13. 14. 15. 16. 17. 18.
Optimum use and long-term effects on production and on ecosystems of organic and inorganic fertilizers. Use and role of fire in ecosystems modification. Ecology and performance of wild and domesticated grazing and browsing animals.
Geoforum
4/1970
93
19.
Studies on the ecology of decomposer organisms and on the effects of man-made changes in the environments on the recycling capacity of soil organisms.
tions, however. it can also serve as a pattern for smaller urban centres. After this exercise similar patterns for typical rural settlements could easily be worked out by teachers and students.
20. 21.
Ecology and rational use of island ecosystems. Human adaptation, land use and environmental relationships in extreme environments, including deserts, high mountains, polar and subpolar regions.
22.
Impact of urban ecosystems on the structure and functioning of the biosphere. Effects on man and his environment of major engineering projects, river-basin developments, pest and disease eradication schemes and other major modifications of ecosystems. Effects on man and his environment of recreation, tourism and related developments.
For didactic reasons and to facilitate memorization the order chosen is strictly alphabetical For reasons of simplicity, I have left out of this classification the important communication links. some of which are included in the sketch ; for example. the main railway station, which is usually not quite centrally situated because of its fairly late introduction in the 19th and 20th centuries ; and the airport. which for obvious reasons is generally between S-10 miles outside the city. Inland water-ways. river ports. harbours etc. can be added to suit local conditions (Fig. 1).
23.
24. 25.
Ecology and rational use of estuarine regions and the coastal zone.
26.
Environmental and socioeconomic criteria influencing optimum use of vaious biotic regions as a basis for urban, rural and regional planning.
27.
Perception and definition of the ecological and cultural bases for environmental quality.
28.
Inventories and toxicology of environmental pollutants.
29.
Monitoring of global changes in pollutant levels. Investigations of man’s long-term influence on the heat balance of the Earth.
30. 31.
Systematic observations of the factors and processes leading to eutrophication and chemical pollution of fresh waters. Within the proposed International Coordinating Council, scientists from twenty-five Member States as well as representatives of other United Nations Agencies and scientific unions, will advise on a more detailed and specialized programme, setting up priorities. The first meeting of this Council will take place in 1971 so that the programme, assisted by workinggroups and expert panels, may become operational in 1972.
Fig. 1 A Simple Teaching Model Explaining the Spatial Differentiation W. MANSHARD,
of Urban Functions’)
Schematical pattern of functional areas in a typical town (of about 50,000 inhabitants). The scale of A, B, C as compared with D has been exaggerated
Paris
9 In as of to
my experience, the First Year student in a university as well the Sixth Form student, finds it much easier to study the site towns. or to compare their size ln area and population, than grasp the functional pattern of urban centres.
Though the student often has a detailed knowledge of the town ln which he has lived for many years, it is difficult for him to recognlse the functions within his town and to deduce a spatial distribution of typical urban services and amenities. To break through this “barrier” of “not seeing the wood for the trees”, I have in past years used the simple teaching device set out below. After understanding this generalized schematic pattern. students mostly fiid it quite easy to adapt it to their own town. It may also help them to read with more understanding the wldespread geographical and sociological literature on towns. This model may, in my opinion. be applied to any fullyfledged town or city of over 50.000 inhabitants. With suitable modiflca-
A first account of this model with special reference to Ghanaian towns (especially Accra and Kumasi) appeared in the Bulletin of the Ghana Geographical Association VoL 5 1960/l pp. 2124. (The author is indebted to the late Miss F. C. MILLER, University of Southampton, England, for the initial idea.) This simplified teaching model follows the pattern of concentric rings as conceived by BURGESS for European and American cities. In reality, the structure of most African cities is much more complex because of the development of urban areas inhabited by different ethnic groups. Besides the indigenous population. there are the migrants and foreign or “colonial” elements like Europeans, Indians or Lebanese. Often the commercial centre develops where these urban areas touch each other. Also, the market has a special functional role in African townships. (cf; discussion remarks: A. L. MABOGUNJE. International Symposium on Urban Growth in Black Africa and Madagascar, Bordeaux 1970).