All posts by Neetu Singh

Urban Morphology Theories

  • Apart from these theories of urban growth and process of decay there are some models of urban growth & its pattern of landuse in the form of different theories. These include concentric zone theory or concentric ring theory, Axial Development theory, Sector theory and multiple nuclei theory. These theories of urban development patterns are quite important in landuse planning. Because in landuse planning process the main focus is on conversion of individual parcels of land from rural to urban uses and the role of public and private sector in that conversion.
    These theories are an attempt to understand and explain that how an urban area grows and what landuse changes occurs in it. it describes the basic urban structure of a city & dynamics of urban growth in town or city.
    Concentric Zone / Ring Theory:
    The concentric zone theory is based on the pioneering work of Ernest. W. Burgess who have carried out the empirical studies of Chicago and developed the concentric Rings theory. He identified five zones of landuse in the city. The figure developed by him shows the typical process of urban growth by five numbers of concentric circles which emerged & expands form CBD.
    The fist concentric circle of central business District (CBD) represents the center of activity generally close to the site of original settlement. The concentric circle means that some thing which converges to a focal factor. For example if we think of a smaller community the house of a land lord will be the focal point or in ancient or medieval time the palace of king & temple was a focal point in city. Like wise in this theory CBD is that focal point of an urban area. It also represents the old town areas or origin of city which has a central position in expansion.
    The second concentric circle represents the transition zone which consists of mix commercial and industrial land uses. It means the areas around CBD are subject to changes and transformations in which the old residences transform into business and industrial landuse. Such as wholesaling and warehousing activities.
    The third zone represents the landuse of low income housing in metropolitan area which contains old housing units or housing of workers of CBD. It is developed due to easy access to job or working area proximity to place of living.
    The fourth zone represents a middle income housing zone that includes some of the old suburbs. In this zone good residential facilities are evident for high income group where as this zone also comprise exclusive districts for high income people.
    The fifth and final zone is of newer suburban developments or commuters who use the fastest transport routes. This zone consists of high class residences and the outer limit of this zone has one hour journey to CBD. If one analyze this model of given pattern and growth situation it will be evident that, each zone held to invade the outer adjacent zone with a rippling effect. With decline enlarges intro central zone. The basic concept of this theory is that similar activities will locate at the same distance from the center of an urban area. The landuse in each zone depends upon its ability to pay the price for proximity to city center or CBD. In this growth model each zone would have a homogeneous landuse as the physical growth proceed outward from the center and the area occupied would have similar characteristics. From economic point of view the concentric zone is only possible when the site of growth will be located equidistant from center irrespective of direction. According to this theory the process of urban growth is of radial expansion from city center. Although this model is very simple but it has a certain description value.
    Axial Development Theory:
    The axial development theory is a continuation of concentric zone theory because its basic premise is same i.e. accessibility to a single focal point. However in this theory the accessibility is measured in terms of time and physical distance and focus is given to transport facilities in an urban area. This theory explains that as the movement will be concentrated along a particular route therefore development also takes place on this route. Thus urban expansion can be controlled by available transport facilities. It is an extension of each landuse type will develop along major transport route and as a repercussion star shape pattern of landuse will occur in urban built up area. Where as the number of arms of star depends upon the major transport routes in a city.
    The limit to this development along main transport routes is set through the area development closer to center with less distance to center. Therefore basically this theory explains about the shape of urban built up areas by introducing some transport routes in addition to peripheral expansion by transport radials. And in this kind of development the pattern of internal landuse will be of irregularly shaped zones.
    Sector Theory: 
    The sector theory is the refinement of both axial development theory and concentric zone theory. The sector theory was first proposed by Homer Hoyt in 1939. In this theory the focus of attention is a particular landuse growth & development. It suggests the cities grow not in strict concentric zones but rather in sectors similar type of development. This theory explains that the growth takes place along a particular axis of transport route with mainly similar type of landuse. Each sector consist a homogeneous landuse which expands outward in a particular direction away from the CBD. The residential areas might expand along with existing transportation links, topographical features or natural amenities such as Chicago’s gold cost and north suburbs clearly show this pattern.
    Thus the major attempt of sector theory is to explain the pattern of urban growth from the view point of residential landuse changes. According to sector theory the growth of n urban area is related with extension of residential districts or more appropriately said the movement of high income residential areas enclosed on each side by middle income group, develops at the edge of existing settlements. The growth for high income housing develops along fastest transport routes up to and edge of an urban area. Beyond which there may be pleasant open country. Some times the direction of this growth may be established by real estate developers. It is quite common practiced that people try to live near the similar social and income class which results in separation in the residential landuse. And as the higher income people can afford better housing & access to amenable environment therefore they can live away from their work place. Whereas; the low income people line on those locations which are low cost & affordable to them near their workplace. The limitation & in adequacy of sector theory is that it can not define rate of growth in different parts of the city or the causes of urban growth and those factors that affects the location of employment opportunities. Especially in case of low in come housing development around the new employment opportunities in suburban or fringe area as evident in our local context the sector theory is silent.
    Multiple Nuclei Theory:
    The Multiple nuclei theory was developed in 1945 by the Chauncey Harris & Edward Ullman after its initial exploration by Mr. R.D. McKenzie. This theory is quite varied from previous theories & models which explained that down town area or CBD is the only focal pint or nuclei of the city. This theory advocates that down town area or CBD can not be considered as an only nuclei or focal point for growth. This theory explains that in urban area there may be more than one focal point or multiple nuclei that can affect the location of certain land uses with increased intensity. In this theory the landuse patterns are visualized as series of nuclei develops in a city in which each nucleus can have different function.
    Each center develops as nuclei from the spatial interdependence of certain functions. For example manufacturing and transport uses may for on nuclei’s. Like wide hotel, offices and transshipment facilities may develop aro8unjd and air port or sea port areas as evident in Chicago’s’ O’Hare field or KPT area in Karachi. Basically this theory suggests four manor principles of separate nuclei and different districts in it.
    · Principle No 1: Certain activities requires and especial condition of access. For example retailing activity and accessibility had main coordination.
    · Principle No 2: Certain activities get benefited from grouping. For example a particular, single kind of market exists together.
    · Principle No 3: Certain activities are detrimental to each other location. For example some activities require supports services.
    · Principle No 4: Certain activities are unable to afford the market price of most desirable sites.

With the expansion of an urban area more specialized nuclei can emerge. In all major urban areas & cities the CBD is located near the inter city transport. The CBD may not be in the center of city but can be developed at an edge of city or built up areas. It depends on the asymmetrical growth of city or urban area. In an urban area Industry, whole sailing & ware housing develops near inter city transport areas. Where as the heavy industry is located away from the main part of the city or urban areas. As the city size increases the residential districts will show an increasing differentiation. In this way the cultural center and entertainment centers or suburban business districts will take a form of other nuclei in the city. Beyond the built up area, settlements which develops as a repercussion of rail services for commuters and private car use. This theory also explains about the irregular pattern of urban landuse because development occurs from different centers, which means the particular pattern of landuse emerge at each different urban area with no common basic pattern of development.
Conclusively; all the theories explained above adds to our knowledge of the cities. Because when the sectors developed in cities and the transit & highways elongated the landuse patterns; eventually a nuclei develop or more appropriately said that transportation and economic development added new dimensions to the landuse of the city. Therefore whenever the landuse patterns of a large old city is evaluated; that has gone through such changes; it may be possible to find all these landuse patterns. It is very rare that contemporary cities show entirely one theory of the landuse change. Finally it is also evident from these theories or models of urban Growth that it only focused on the affects of growth on urban development pattern. Whereas the causes of urban growth is not addressed in these theories; because all theories have an assumption that an urban area will grow in size or physical morphology will change & the growth of city is taken for granted.
Thus conclusively the current discussion leads us to following realities.
· Urban growth can be spontaneous on its own or planned growth as directed by the authorities.
· The concept of planning is to provide a vision for future well before the people actually settle in the settlements and planning may also be appropriate enough to facilitate the process of housing the poor in the city.
· The basic planning component is that incompatible land uses should not be allowed or located together.
· Circulation, transport, infrastructure and land use management are the basic tools of planning to guide the urban growth and transformation in the city.
· Suburban growth shall be seen as the series of phases through which a particular location passes or it is the development which proceed from an open land to mature urban development.
· The objectives of sound planning should be to develop a set of simple guidelines, or principles which should be comprehensive and adaptable to changing conditions of the future.

URBAN MORPHOLOGY
The city is a global phenomenon. It is also a regional and cultural variable. The descriptions and models that we have used to study the functions, land use arrangements, suburbanization trends, and other aspects of the U.S. city would not in all or even many-instances, help us understand the structures and patterns of cities in other parts of the world. Those cities have been created under different historical, cultural, and technological circumstances. They have developed different functional and structural patterns, some so radically different from our U.S. model that we would find them unfamiliar and uncharted landscapes indeed. The city is universal; its characteristics are cultural and regional
The North American City
Even within the seemingly homogeneous North American culture realm, the city shows subtle but significant differences not only between older eastern and newer western U.S. cities, but between cities of Canada and those of the United States. Although the urban expression is similar in the two countries, it is not identical, and truly “North American city” is more a myth than a reality. The Canadian city, for example, is more compact than its U.S. counterpart of equal population size, with a higher density of buildings and people and a lesser degree of suburbanization of populations and functions. Space saving multiple family housing units is more the rule in Canada, so a similar population size is housed on a smaller land area with much higher densities, on average, within the central area of cities. The Canadian city is better served by and more dependent on mass transportation than is the U.S. city. Since Canadian metropolitan areas have only one-quarter the number of miles of expressway lanes per capita as U.S. MSAs-and as least as much resistance to constructing more suburbanization of peoples and functions is less extensive north of the border than south. It is likely to remain that way.
In social as well as physical structure, Canadian-United States contrasts are apparent. While cities in both countries are ethnically diverse, Canadian communities, in fact, have the higher proportion of foreign born – U.S. central cities exhibit far greater internal distinctions in race, income, and social status and more pronounced contrasts between central city and suburban residents. That is, there has been much less “flight to the suburbs” by middle-income Canadians. As a result, the Canadian city shows greater social stability, higher per capita average income, more retention of shopping facilities, and more employment opportunities and urban amenities than its U.S central city counterpart. In particular, it does not have the rivalry from well-defined competitive “outer cities” of suburbia that so spread and fragment United States metropolitan complexes.
The Western European City

If such significant urban differences are found even within the lightly knit North American region, we can only expect still greater divergences from the U.S. model at greater linear and cultural distance and in countries with long urban traditions and mature cities of their own. The political history of France, for example, has given to Paris an over-whelmingly primate position in its system of cities. Political, economic and colonial history has done the same for London in the United Kingdom. On the other hand, Germany and Italy came late to nationhood, and no over-whelmingly dominant cities developed in their systems.
Nonetheless, a generally common heritage of medieval origins, renaissance restructuring and industrial period extensions has given to the cities of Western Europe features distinctly different from those of cities in other regions founded and settled by European immigrants. Despite wartime destructions and postwar redevelopments, many still bear the impress of past occupants and technologies, even back to Roman times in some cases. Although the European urban pattern we see today is primarily the product of the industrialization of the 19th and 20th centuries, frequently the location and shape of the settlement, the street pattern, and the layout of the older sections are more a reminder of the distant past than a reflection of modern requirements and responses. An irregular system of narrow streets may be retained from the random street pattern developed in medieval times of pedestrian and pack-animal movement. A system of main streets radiating from the city center and cut by circumferential “ring roads” tells us the location of high roads leading into town through the gates in city walls now gone and replaced by circular boulevards. Broad thoroughfares, public parks, and plazas mark renaissance ideals of city beautification and the esthetic need felt for processional avenues and promenades.
Although each is unique historically and culturally, Western European cities as a group share certain common features that set them apart from the United States model, though they are less far removed from the Canadian norm. Cities of Western Europe have, for example, a much compact form and occupy less total area than American cities of comparable population; most of their residents are apartment dwellers. Residential streets of the older sections tend to be narrow, and front, side, or rear yards or gardens are rare. European cities developed for pedestrians and still retain the compactness appropriate to walking distances. The sprawl of American peripheral and suburban zones is generally absent. At the same time, compactness and high density do not mean skyscraper skylines. Much of urban Europe predates the steel-frame building and the elevator. City skylines tend to be low, three to five stories in height, sometimes (as in central Paris) held down by building ordinance or by prohibitions on private structures exceeding the height of a major public building, often the central cathedral.
Compactness, high densities, and apartment dwelling encouraged the development and continued importance of public transportation, including well-developed subway systems. The private automobile has become much more common of late, though most central city areas have not yet been significantly restructured with wider streets and parking facilities to accommodate it. The automobile is not the universal need in Europe that it has become in American cities. Home and work are generally more closely spaced in Europe – often within walking or bicycling distance -while most sections of towns have first-floor retail and business establishments (below upper-story apartments), bringing both places of employment and retail shops within convenient distance of resistances.
A very generalized model of the social geography of the Western European city has been proposed. Its exact count part can be found nowhere, but many of its general features are part of the spatial social structure of most major European cities. In the historic core, now increasingly gentrified, residential units for the middle class, the self-employed, and the older generation of skilled artisans share limited space with preserved historic buildings, monuments, and tourist attractions. The old city fortifications may mark the boundary between the core and the surrounding transitional zone of substandard housing, 19th century industry, and recent immigrants. The waterfront has similar older industry; newer plants are found on the periphery. Public housing and some immigrant concentrations may be near that newer industry, while other urban socioeconomic groups aggregate themselves in distinctive social areas within the body of the city. The European city does not characteristically feature the ethnic neighborhoods of U.S. cities although some, like London, do. Rather, its guest workers from Eastern Europe, the Near East, and North Africa tend to be relatively dispersed rather than concentrated. Nor is it characterized by inner-city deterioration and out-migration. Its core areas tend to be stable in population and to attract rather than repel the successful middle class and the upwardly mobile, conditions far different from comparable sections of older U.S. central cities.
Cities of Eastern Europe make up a separate urban class, the socialist city. It is an urban form that shares many of the traditions and practices of Western European cities, but it differs from them in the centrally administered planning principles that have been designed to shape and control both new and older settlements. The particular concerns have been, first, limitation on size of cities to avoid super city growth and metropolitan sprawl; second, assurance of an internal structure of neighborhood equality and self-sufficiency; and third, strict land use segregation. The socialist city has fully achieved none of these objectives, but by attempting them it has emerged as a distinctive urban form.
Within the vast domain of the Soviet Union, where the planning philosophies of the socialist city were formulated, urbanization has proceeded rapidly during the period of communist rule. Urban population has increased from about 18% (1917) to 66% (1989) of total population, some 150 million new urban residents have been accommodated, and over 1500 new or largely rebuilt cities have been created in general accordance with the socialist city model. Although the Eastern European countries taken into the Soviet bloc following World War II were in general, more urbanized than the USSR had been, they too have experienced and acceleration of urbanization on the Soviet model with recent industrialization. As a group, they add another 71 million urbanites to the 191 million Soviet city residents (1989).
Although city planning In the Soviet Union has not been rigorously or consistently applied, often thwarted because city governments responsible for planning are powerless to control or change site decisions made by economic ministries – the accepted planning guidelines have made themselves evident in the urban landscape. In general structural terms, the socialist (Soviet) city is compact, with relatively high building and population densities reflecting the nearly universal apartment dwelling, and with a sharp break between urban and rural land uses on its periphery. Like the older-generation Western European city, the socialist city depends exclusively on public transportation.
It differs from its Western counterpart, of course, in its purely governmental rather than market control of land use and functional patterns. That control has dictated that the central area of cities should be reserved for public use, not occupied by retail establishments or office buildings on the Western, capitalist model. A large central square ringed by administrative and cultural buildings is the preferred pattern. Nearby, space is provided for a large recreational and commemorative park. Neither a central business distinct nor major outlying business districts are required or provided in the socialist city, for residential areas are expected to be largely self-contained in the provision of at least low-orders goods and services, minimizing the need for a journey to centralized shopping locations. Those residential areas are made up of “micro districts,” assemblages of uniform apartment blocks housing perhaps 10,000 to 15,000 people, surrounded by broad boulevards and containing centrally sited nursery and grade schools, grocery and department stores, theaters, clinics, and similar neighborhood necessities and amenities. Plans call for effective separation of residential quarters from industrial districts by landscaped buffer zones, but in practice many micro-districts are built by factories for their own workers and are located immediately adjacent to the workplace.
Since micro-districts are most easily and rapidly constructed on open land at the margins of expanding cities, high residential densities have been carried to the outskirts of town. The distance decay curve of declining population densities outlined does not apply to the socialist city. Although egalitarian planning principles demand uniformity in the housing stock and a total prohibition of any form of residential segregation, in practice uniformity is not achieved and segregation does occur. To the extent that the housing stock is built by industrial and institutional entities for their own workers (perhaps a third or more of all nits), segregation of housing by place of employment is automatic. Further, some sections of most cities are seen as more prestigious and desirable than others, and those citizens able through income or influence to locate within them do so, establishing elite neighborhoods in a city equals.
The Soviet ideal has long been for cities to achieve but not exceed a size in which (1) the provision of public (2) reasonable scale economies of agglomeration are possible, and (3) the diseconomies of peripheral spread, congestion, commuting costs, pollution, and the like are avoided. In particular, massive metropolitan sprawl and conurbations are to be avoided. Since domestic migration is controlled and Soviet citizens (and Eastern Europeans in general) must have permits to live and work in given locales, control of city size would appear simple. In reality, it has not proved so – again because economic ministries can make vocational decisions without reference to individual city plans or goals. Thus, the Moscow metropolitan area approximates 10 million in an urban sprawl in many ways reminiscent of that of Western cities, and other major socialist cities show similar tendencies to spread.
Cities in the Developing World
Still farther removed from the United States urban model are the cities of Africa, Asia, and Latin America, where industrialization has come only recently or not at all where modern technologies in transportation and public facilities are barely known or sparsely available, and where the structures of cities and the cultures of their inhabitants are far different from the urban world familiar to North Americans. The developing world is vast in extent and diverse in physical and social content; generalizations about it or its urban landscapes lack certainty and universality. Islamic cities of North Africa, for example, are entities sharply distinct from the black African, the Southeast Asian, or the Latin American city. Yet, by observation and consensus, some common features of Third World cities are recognizable. All, for example, have endured massive in-migrations from rural areas. As a result, most are ringed by vast squatter settlements high in density and low in public facilities and services. All, apparently, have populations greater than their formal functions and employment bases can support. In all, large numbers support themselves in the ‘informal” sector as snack-food vendors, peddlers of cigarettes or trinkets, street-side barbers or tailors, errand runners or package carriers and the like outside the usual forms of wage labor.
But the extent of acceptable generalization is limited, for the backgrounds, developmental histories, and current economies and administrations of Third World cities vary greatly. Some are still pre-industrial, without a central commercial core, without industrial districts, without public transportation, without any meaningful degree of land use separation. Some are the product of Western colonialism, established as ports or outposts of administration and exploitation, built by Europeans on the Western model, though increasingly engulfed by later, indigenous urban forms. In some, Western-style skyscraper central areas and commercial cores have been newly constructed. In others, commerce is conducted in different forums and formats.
Wherever the automobile and modern transport systems are an integral part of the growth of Third World cities, the metropolis begin to take on Western characteristics. On the other hand, in places such as Bombay (India), Lagos (Nigeria), Jakarta (Indonesia), Kinshasa (Zaire), and Cairo (Egypt), where modern roads have not yet made a significant impact and the public transport system is limited, the result has been overcrowded cities centered on a single major business district in the old tradition. In such societies, the impact of urbanization and the responses to it differ from the patterns and problems observable in the cities of the United States.
The developing countries, emerging from earlier dominantly subsistence economics, have experienced disproportionate population concentrations, particularly in their national and regional capitals. Lacking or relatively undeveloped is the substructure of maturing, functionally complex smaller and medium-sized centers characteristic or more advanced and diversified economies. The primate city dominates their urban systems. Greater Cairo contains nearly 30% of Egypt’s total population; 30% of all Nicaraguans live in Managua; and Baghdad contains 24% of the Iraqi populace. Vast numbers of surplus, low-income rural populations have been attracted to these developed seats of wealth and political centrality in type hope of finding a job. Although attention may be lavished on creating urban cores on the skyscraper model of Western cities, most of the new urban multitudes have little choice but to pack themselves into squatter shanty communities on the fringes of the city, isolated from the sanitary facilities, the public utilities, and the job opportunities that are found only at the center. In the sprawling slum district to Nairobi, Kenya, called Mathare Valley, some 250,000 people are squeezed into 6 square miles (15.5 km2) and are increasing by 10,000 per year. Such impoverished squatter districts exist around most major cities in Africa, and Latin America. Proposed models of third World urban structure demonstrate the limits of these generalizations. The same models (and others) help define some of the regional and cultural contrasts that distinguish those cities.
The port and its associated areas in the large composite Southeast Asian city were colonial creations, retained and strengthened in independence. Around them are found a Western-style central business district with European shops hotels, and restaurants; one or more “alien commercial zones’ where merchants of the Chinese and, perhaps, Indian communities have established themselves; and the more widespread zone of mixed residential, light industrial, and indigenous commercial uses. Central slums and peripheral squatter settlements house up to two-thirds of the total city population. Market gardening and recent industrial development mark the outer metropolitan limits.
The South Asian city appears in two forms – the internal structure of the colonial-based city, making clear the spatial separation of native and European residential areas, the mixed-race enclave between them, and the 20th century new-growth areas housing the wealthier local elites; and the traditional bazaar city, its center focused upon a crossroads around which the houses of the wealthier residents are situated. Merchants live above or behind their shops, and the entire city center is characterized by mixed residential, commercial, and manufacturing land uses. Beyond the inner core is, first, an upper-income residential area shared (but not in the same structures) with poorer servants.
Still farther out are the slums and squatter communities, generally sharply segregated according to ethnic, religious, or caste status or native village of their inhabitants.
The Latin American city is more thoroughly “Westernized” than its Asian or African counterparts, but it shows many of the same land use arrangements. The focal core is a central business district on the North American and European model, served by a well-developed mass transit system and having the full range of urban services and amenities. It therefore retains its attraction for middle and upper-income residents who contribute to its upgrading and modernization through new apartment construction. A commercial “spine,” essentially an extension of the CBD, leads away from the core. Bordering it in an ever-widening elite sector are the upper-income housing districts, the best theaters and restaurants, modern office buildings, exclusive shops, major boulevards, and wealthiest suburbs. The area occupied by the urban elites far exceeds their proportion of total population.
The far greater numbers of lower-income and destitute urban residents occupy the concentric zones spaced around the core. The inner “zone of maturity” houses the middle class in solid structures, well maintained. The “in-situ” zone is one of more modest and mixed residential quality, under continuing reconstruction and upgrading as its residents improve their economic status. At its outer margins, however, it fades into the “peripheral squatter settlements” zone, the outer ring housing in the urban area’s worst shantytowns and sums the most impoverished and most recent in-migrants to the city.
Each of these models presents a variant of the developing world’s urban dilemma: an urban structure not fully capable of housing the peoples so rapidly thrust upon it. Populations of Third World cities in the late 1980s were growing by 3.5% annually, three times faster than urban growth in the Western world. The extreme case was Africa, where a 5% annual growth rate implied a doubling of city populations in 14 years. These numerical increases exceed urban support capabilities, and unemployment rates of 25% are common in cities of the developing world. There is little chance to reduce them as additional millions – through natural increase and in-migration, swell cities already overwhelmed by poverty, lack of sanitation facilities, inadequate water supplies, antiquated public transportation, and spreading slums. The problems, cultures, environments, and economies of Third World cities are tragically unique to them. The urban models that give us understanding of United States cities are of little assistance or guidance in such vastly different culture realms.
Summary
The city is the essential functional node in the chain of linkages and interdependencies that marks any society or economy advanced beyond the level of subsistence. The more complex and functionally integrated the society, the greater the degree of specialization and exchange that it demands for its maintenance, and the more urbanized it becomes. Although cities are among the oldest marks of civilization, only in this century have they become the home of the majority of the people in the industrialized countries and the inhospitable place of refuge for uncounted millions in modernizing Third World economies. At the global scale, four major world urban regions have emerged; Western Europe, South Asia, East Asia and North America. Within those regions, metropolitan expansion has created massive conurbations.
All cities growing beyond their village origins take on functions uniting them to the countryside and to a larger system of cities; all, as they grow, become functionally complex. Their economic base may become diverse and is comprised of both basic and service activities. The former represent the functions performed for the larger economy and city system, the later those present to satisfy the needs of the urban residents themselves. Functional classifications distinguish the economic roles of cities, while simple classification of them as transportation and special function cities or as central places helps define and explain their functional and size hierarchies and the spatial patterns they display within a system of cities.
As North American urban centers expanded in population size and diversity, they developed more or less structured land use patterns and social geographies based on market allocations of urban space, channelization of traffic, and largely voluntary socioeconomic aggregation. The observed regularity of land use arrangements has been summarized for U.S. cities by the concentric zone, sector, and multiple-nuclei models. Social area counterparts of land use specializations were based on social status, family status and ethnicity. Since 1945, these older models of land uses and social areas have been modified by the suburbanization of people and functions that has led to the creation of new and complex outer cities and to the deterioration of the older central city itself.
Urbanization is a global phenomenon, and the U.S. models of city systems, land use structures, and social geographies are not necessarily or usually applicable to other cultural contexts. Models descriptive of Third World city structures do little to convey the nature of their universal dilemmas of intense overcrowding, poverty, and inadequate physical structure.

 

 

Earthquake and Earth’s Interior

An earthquake is the vibration of Earth produced by the rapid release of energy. Most often earthquakes are caused by slippage along a fault in earth’s crust. The energy released radiates in all directions from its source, the focus, in the form of waves. These waves are analogous to those produced when a stone is dropped into a calm pond. Just as the impact of the stone sets water waves in motion, an earthquake generates seismic waves that radiate throughout Earth. Even though the energy dissipates rapidly with increasing distance from the focus, sensitive  instruments located around the world record the event.

Earthquakes and Faults

The tremendous energy released by atomic explosions or by volcanic eruptions can produce an earthquake, but these events are relatively weak and infrequent. Ample evidence exists that Earth is not a static planet. We know that Earth’s crust has been uplifted at times, because we have found numerous ancient wave-cut benches many meters above the level of the highest tides. Other regions exhibit evidence of extensive subsistence. In addition to these vertical displacements, offsets on fence lines, roads, and other structures indicate that horizontal movement is common. These movements are usually associated with large fractures in Earth’s crust called faults.

Most of the motion along faults can be satisfactorily explained by the plate tectonics theory.

This theory states that large slabs of Earth’s crust are in continual slow motion. These mobile plates interact with neighboring plates, straining and deforming the rocks at their edges. In fact, it is along faults associated with plate boundaries that most earthquakes occur. Furthermore, earthquakes are repetitive: as soon as one is over, the continuous motion of the plate’s resumes, adding strain to the rocks until they fail again.

Elastic Rebound

The actual mechanism of earthquake generation eluded geologists until H.F. Reid of Johns Hopkins University conducted a study following the great 1906 San Francisco earthquake.

As slippage occurs at the weakest point (the focus), the displacement will exert stress farther along the fault, where additional slippage will occur until most of the built-up strain is released. This slippage allows the deformed rock to “snap back”.

The vibrations we know as an earthquake occur as the rock elastically returns to its original shape. The “springing back” of the rock was termed elastic rebound by Reid, because the rock behaves elastically, much like a stretched rubber band does when it is released.

In summary, most earthquakes are produced by the rapid release of elastic energy stored in rock that has been subjected to great stress. Once the strength of the rock is exceeded, it suddenly ruptures, causing the vibrations of an earthquake. Earthquakes also occur along existing fault surfaces whenever the frictional forces on the fault surfaces are overcome.

Foreshocks and Aftershocks

The adjustments that follow a major earthquake often generate smaller earthquakes called aftershocks. Although these aftershocks are usually much weaker than the main earthquake, they can sometimes destroy already badly weakened structures. A large aftershock of magnitude 5.8 collapsed many structures that had been weakened by the main tremor.

In addition, small earthquakes called foreshocks often precede a major earthquake by days or, in some cases, by as much as several years. Monitoring of these foreshocks has been used a means of predicting forthcoming major earthquakes, with mixed success.

Seismology

The study of earthquake waves, seismology, dates back to attempts made by the Chinese almost 2000 years ago to determine the direction from which these waves originated. The seismic instrument used by the Chinese was a large hollow jar that probably contained a mass suspended from the top. This suspended mass (similar to a clock pendulum) was connected in some fashion to the jaws of several large dragon figurines that encircled the container. The jaws of each dragon held a metal ball. When earthquake waves reached the instrument, the relative motion between the suspended mass and the jar would dislodge some of the metal balls into the waiting mouths of frogs directly below.

The Chinese were probably aware that the first strong ground motion from an earthquake is directional, and when it is strong enough, all poorly supported items will topple over in the same direction. Apparently the Chinese used this fact plus the position of the dislodged balls to detect the direction to an earthquake’s source. However, the complex motion of seismic waves makes it  unlikely that the actual direction to an earthquake was determined with any regularity.

In principle at least, modern seismographs, instruments that record seismic waves, are not unlike the device used by the early Chinese. Seismographs have a mass freely suspended from a support that is attached to the ground. When the vibration from a distant earthquake reaches the instrument, the inertia of the mass keeps it relatively stationary, while Earth and support move. The movement of Earth in relation to the stationary mass is recorded on a rotating drum or magnetic tape.

Earthquakes cause both vertical and horizontal ground motion; therefore, more than one type of seismograph is needed. The instrument is designed so that the mass is permitted to swing from side-to-side and thus it detects horizontal ground motion. Usually two horizontal seismographs are employed, one oriented north-south and the other placed with, an east-west orientation. Vertical ground motion can be detected if the mass is suspended from a spring.

To detect very weak earthquakes, or a great earthquake that occurred in another part of the world, seismic instruments are typically designed to magnify ground motion. Conversely, some instruments are designed to withstand the violent shaking that occurs very near the earthquake source.

The records obtained from seismographs, called seismograms, provide a great deal of information concerning the behavior of seismic waves. Simply stated, seismic waves are elastic energy that radiates out in all directions from the focus. The propagation (transmission) of this energy can be compared to the shaking of gelatin in bowl, which results as some is spooned out. Whereas the gelatin will have one mode of vibration,  seismograms reveal that two main groups of seismic waves are generated by the slippage of a rock mass. One of these wave types travels along the outer part of Earth. There are called surface waves. Others travel through Earth’s interior and are called body waves. Body waves are further divided into two types called primary of P waves and secondary or S waves.

Body waves are divided into P and S waves by their mode of travel through intervening materials. P waves are “push-pull” waves – they push (compress) and pull (expand) rocks in the direction the wave is traveling like  holding someone by the shoulders and shaking that person. This push-pull movement is how P waves move through Earth.

This wave motion is analogous to that generated by human vocal cords as they move air to create sound. Solids, liquids, and gases resist a change in volume when compressed and will elastically spring back once the force is removed. Therefore, P waves, which are compression waves, can travel through all these materials.

On the other hand, S waves “shake” the particles at right angles to their direction of travel which is like fastening one end of a rope and shaking the other end. Unlike P waves, which temporarily change the volume of intervening material by alternately compressing and expanding it, S waves temporarily change the shape of the material that transmits them. Because fluids (gases and liquids) do not respond elastically to changes in shape, they will not transmit S waves.

 motion of surface waves

The motion of surface waves is somewhat more complex. As surface waves travel along the ground, they cause the ground and anything resting upon it to move, much like ocean swells toss a ship. In addition to their up-and-down motion, surface waves have a side-to-side motion similar to an S wave oriented in a horizontal plane. This latter motion is particularly damaging to the foundations of structures.

Because surface waves are confined to a narrow region near the surface and are not spread throughout Earth as P and S waves are, they retain their maximum amplitude longer. Surface waves also have longer periods (time interval between crests); therefore, they are often referred to as long waves, or L waves.

Seismic waves are useful in determining the location and magnitude of earthquakes. In addition, they provide a tool for probing Earth’s interior.

 

MAJOR INDUSTRIAL REGIONS OF THE WORLD

MAJOR INDUSTRIAL REGIONS OF THE WORLD  (विश्व के प्रमुख औद्योगिक क्षेत्र)
Industrial regions are those areas, where concentration of industries has occurred due to favorable geo-economic conditions. These are areas within which manufacturing industry is carried out on a relatively large scale and employs a relatively large proportion of population.
The spatial distribution of manufacturing units shows a distinct trend of localization towards a few selected areas; these regions are referred to as ‘industrial regions’.
The common characteristic features of the industrial regions are:
· Large population engaged in industrial pursuits,
· Large industrial complex in hierarchical order,
· Integration of some main industries with a group of subsidiary industries,
· Large banking and credit facilities,
· A network of communication lines, and
· A large market for labour supply, etc.
The industrial regions of the world are very unevenly distributed over the face of the earth. Both natural and cultural factors are involved in any explanation of the distribution of manufacturing regions of the world, but the great differentiations in localization of any industrial region can be explained to a large degree by the availability of resources.
Since the development of machinery, many industrial centers have sprung up where there is abundance of coal, or coal and iron, or extensive water-power – the mainsprings of modern industry, and all such towns are more or less business centers.
There are several factors affecting the concentration or localization of industry. The main localizing factors are: the market, the labor supply, the cost of land resources, the situation of raw material, the nature and situation of the natural and human resources, the value of the commodities produced in relation to the cost of the various items entering into their production, and finally, the supply of capital.
It is obvious that the profitableness of large scale operations must depend on the adequacy of the market, which is governed by various conditions as:

· The number of people where the industry is carried on.
· The purchasing power of the people, a great contrast in this respect being presented by developing countries as compared with developed countries and other semi-developed countries, in which the letter’s purchasing power is enhanced by the diffusion of education, and probably still more by the extent of the available undeveloped resources.
· The nature of the commodity for which a market is sought – cheap goods for peoples of small purchasing power, more valuable commodities for regions in which individual wealth is greater.
· Facilities for transport in enlarging the range of the market.
The spatial distribution of the industries shows a trend of concentration or agglomeration of industries in few regions where geo-economic conditions of industrial growth are favorable. These industrial regions have variety of industries and other infrastructures and are famous for their production of particular or varied types of industrial goods.
The major industrial regions of the world are as follows:
· North American region, comprising USA and Canada.
· European region, consisting of the industrial region of UK, Germany, France, etc.
· Industrial region of Russia
· Asian region, comprising the industrial regions of Japan, China, India, etc.
· Other isolated industrial regions.
NORTH AMERICA
• Manufacturing in North America is concentrated in the northeastern quadrant of the United States and in southeastern Canada.
• Only 5 percent of the land area of these countries.., contains one-third of the population and nearly two-thirds of the manufacturing output.
• This manufacturing belt has achieved its dominance through a combination of historical and environmental factors. North America Three Determining Location Factors:
• Population Proximity- Early settlement gave eastern cities an advantage to become the country’s dominant industrial center.
• Access to Raw Materials- had essential raw materials (by waterway or natural resources).
• Transportation- The Great Lakes and major rivers were a early determining factor is waterway transportation.
• Access to fresh water and power- proximity to great lakes
North American industrial region comprising of USA and Canada is a highly developed industrial region of the world. USA is now the wealthiest and most highly developed nation in the world. Southern Canada is also well developed.
The USA has become the world’s greatest industrial country. She had the immense advantages of space and virgin resources. The speed at which the industrial pattern of the USA is shifting and changing today is, in some sense, a measure of her industrial wealth and of the newness of her development.
The continent was peopled from the east. The oldest centers of industry lie along the eastern seaboard or in the valleys of the eastward flowing rivers. The industrial centers of the Middle West and of the Pacific coast are more recent.
The North American continent has many great industrial centers and a few industrial regions. This is partly the consequence of the widespread nature of the resources of the continent, and partly because of the late date at which industrialization took place.
The development of transport facilities and in recent years the generation and transmission of hydroelectric power have tended to cut industry adrift from the coalfields It is now having few areas of large scale concentration

The industrial regions of USA are as follows:

Southern New England:
This part of USA was the earliest to be developed by the settlers from England. Therefore, industrial growth also started earlier in this region. This is one of the oldest industrial regions in USA having a diversified industrial growth. The nucleus of the region is Boston with Connecticut; Massachusetts and Rhode Island are other major centers.
The two dominant industries which developed in this region are shipbuilding and textile, but both have now declined as newer centers with greater advantages have emerged in the Mid-Atlantic States, the Great Lakes and the West.
The engineering industry is still important, especially for the production of specialised goods, such as electrical machinery at Springfield, aircraft and armaments in Hartford, instrument-making at Bridgeport and textile-machinery manufacture at Worcester, Lowell and New Bedford.
Two towns, Boston and Beverly, are specialized in footwear machinery and the former is a shoemaking centre. The traditional textile towns are Lowell and Providence for woollen textiles; and New Bedford, Worcester and Fall River for cotton textiles; but these now produce mainly high-quality goods. Mass production is now more economic, farther south.
Mid-Atlantic States:
This region has a great diversity of manufactures. Inland, the variety of product, from the wrist watch to the giant locomotive; from the coarsest cotton to the finest silk; and from the deadliest and most powerful chemicals to perfumes are the outstanding characteristics of this industrial development.
Abundance of cheap and good anthracite coal of Pennsylvania, oil and natural gas from Appalachians have been important factors in encouraging development in the Mid-Atlantic Region. Coal is used in all units of this industrial region as a source of power but oil and gas are also important sources of energy. This is also the most densely populated part of the United States, a main source of skilled labor force, and this is also the main basis for the growth of enormous industrial conurbation from New York to Baltimore.
New York, situated on Manhattan Island, at the mouth of this important Hudson route from the interior via the Mohawk and Hudson valleys, is the largest city in the United States. It has an excellent harbour, and kilometers of wharves along the shores of the Manhattan Island and Long Island.
Leading industries were food and allied products; clothing and other textile products; printing and publishing; chemical and allied products; electrical equipment; transport equipment; and instruments. The town of Albany lies near the confluence of the Mohawk and the Hudson, and is noted for iron and steel manufactures.
Pittsburgh-Lake Erie Region:
This is the region having greatest concentration of ferrous industries. This region accounts about one-fourth of ferrous and ferro-alloy products of the country. The famous Youngstown-Pittsburgh-Johnstown iron and steel triangle is located in the region. The other steel-producing areas are Wheeling, Cleveland, Louisville, Rookford, Flint, Steubenville and Detroit.
The other manufacturing centres engaged in diversified manufacturing activities are Chicago, Anderson, Midland, Iowa, St. Louis, Minneapolis, etc. In cities like Detroit, several industries have developed including motor vehicles, machinery, fabricated metals, machine tools and electronics.
It also spreads down the Ohio River to Weirton, Steubenville, wheeling Huntington, Ashland, Ironton and Portsmouth and up the Miami valley to Middletown. Pittsburgh also has the largest glass industry in the United States. Most of the ore comes from Lake Superior. Cleveland, on Lake Erie, is noted for iron goods, electrical engineering and machineries.
Detroit Industrial Region:
This is the greatest automobile manufacturing region of the USA, centered at Detroit. The city was at first a centre for wagon and carriage-making which later led to the assembly of automobiles in the region.
It is the headquarters of several giant motor corporations including Ford, Chrysler, and General Motors. Other location advantages were the large market for cars in the Midwest, where other forms of transport, e.g., railways, were relatively poorly developed in the early 20th century; and the ease of transporting steel from Pittsburgh via Lake Erie.
The automobile industry extends to many other towns around Detroit, e.g., Lansing, Flint, Jackson, Pontiac, Dearborn and Toledo; and car assembly is linked with other branches of manufacture such as tyre-making, electrical wires, glass, batteries, paints, polishes, alloyed steel, spare parts and components.
Lake Michigan Region:
This area lies on the southern shores of Lake Michigan with Chicago as a main centre. There are some 10,000 factories in and around Chicago, amongst which the iron and steel plants are the most important.
The manufacturing industries around Lake Michigan are confined largely to Chicago and Gary where iron ore of the Lake Superior and of north meets coal from the south. Chicago, near the head of Lake Michigan, is now the second largest city in the United States.
Its chief advantage lies in the fact that railways from the north-west are obliged to pass through it in rounding Lake Michigan to reach the Atlantic, while it also forms a good centre for railways from the south. Chicago concentrates on motor vehicles and trucks, cement, chemicals, iron and steel goods, furniture, paper, cereal, baby food and pharmaceuticals.
Other industries are based on the agricultural products of the surrounding regions, e.g., meat-packing, grain milling and the making of agricultural implements and machinery. Gary near Chicago is important for iron and steel production.
Closely associated with the Chicago metropolitan area are such urban centres as Milwankee, Racine and Kenosha with their extensive iron and steel, motor vehicle, beverage, machinery, meat packing, leather and leather goods establishments. Chicago, Gary and Milwankee depend upon it now for the delivery of Upper Lake ore.
Southern Appalachian Region:
This is a very distinctive steel making area centred at Birmingham in the piedmont of the southern Appalachians in the state of Albania. The availability of coal and iron, later supplemented by oil and hydroelectric power from the Fall line are responsible for the growth of this industrial area. Other industrial cities of this region are Atlanta, Gadsden, Bessemer, Anniston and many others.
Cotton textiles and chemicals are now manufactured in several industrial towns of this industrial region where water power is available. It makes a very wide range of goods such as metal works, chemicals and machinery manufacture.
Eastern Texas:
The industrial development of this region is based on oil, as a source of fuel and as a raw material. The main centres of this region are cities of Dallas and Houston. This region is also rich in sulphur, rock salt and phosphate rock. This makes oil refining and chemical industries the most important in the region. Their situations on the coast have additional advantage of transportation.
The capital available by the oil industry helps in industrial development. Dallas has more than twelve oil refineries, chemical plants, synthetic rubber factory as well as steel milling and manufacture of mining equipment and consumer products. Dallas also has clothing and fashion industry and Fort Worth is famous for aircraft and aerospace industries.
Pacific Coastal Region:
This region is a narrow coastal strip running through Washington, Oregon and California. This is one of the great industrial agglomerations of the Pacific coast. Its industrial centers are San Francisco and Los Angeles.
This region is famous for food and beverages, automobiles, aircraft, metal fabrication, petrochemical and heavy chemical industries. The other industrial centres of this region are Portland, Seattle, Engine, Sacramento, San Diego, etc.
Apart from the above mentioned industrial regions, there are some large isolated industrial centres in USA which are known for their industrial products. St. Louis has meat-packing, flour-milling, footwear, and agricultural machinery industries. Kansas City has similar manufacture of products plus aircraft and oil refining.
Others like Omaha, Cincinnati, Indianapolis, Denver, St. Paul and Minneapolis, and Memphis concern themselves mainly with agricultural industries, being located in the midst of America’s richest agricultural region. Flour-milling, meat-packing, cotton textiles and food processing are some of the major industrial undertakings.
Bordering the Gulf of Mexico are several towns that serve as the outlets of the Mississippi basin and have industries linked with the oil found in the region. New Orleans has oil refining, chemicals and cotton textile industries.
Major Industrial Regions of Canada
In North America, Canada is the second largest industrial region. The country is rich in mineral resources like iron ore, petroleum and forest resources and also has abundant hydroelectric power.
Ontario and St. Lawrence Valley:
This is one of the most important manufacturing regions in Canada. The major products are paper, cheese, flour, agricultural machinery, copper and nickel smelting, iron and steel industry and chemical industry. The major industrial centres are Quebec, Ontario, Ottawa, Toronto, Hamilton, etc.
Prairie Region:
As far as manufacturing industry is concerned, this region is not very developed. The major centres of production are Manitoba, Winnipeg, Edmonton, Alberta, etc. Besides agro-based industries, the other noted industries in the region are petroleum refinery and chemical industry.
Pacific Coastal Region:
In this region industry like paper and pulp, furniture, agricultural machinery, etc., have been developed. The major industrial centres of this region are Vancouver and Prince Rupert.

EASTERN ASIA

• Access to Raw Materials- the Asia Pacific region is one of the major growing regions of natural fabrics such as cotton. Also has large coal and iron deposits
• Transportation- Near the oceans and waterways for transport
• Labour Supply- the Asian countries are some of the most densely populated areas of the planet meaning there are a lot of labourers available that also work for low wages
In Asia, China, Japan and India have done considerable progress in industrial development. Hong Kong, Korea and Taiwan have become major exporters of textile and other goods.
The South-East Asian Region, though traditionally agricultural in outlook, is also developing industries. Singapore is the most industrialized of the South-East Asian countries. Oil is the major resource of Middle East; therefore, oil refining and petrochemical industry have become important in the region. Iran has developed a wide range of industries.

Chinese industrial regions
Industrial development in China began only after the beginning of Communist rule in 1949, and now China is not only art industrial power of Asia but also of the world. There has been a complete transformation of the industrial system during the last 60 years.
Under the new system and policy, China is developing its industrial system in a planned manner. Rapid development has made China a leading producer of iron and steel, textiles, and cheap consumer goods such as toys, household goods and light metal goods. In China, following industrial regions have been identified:
Manchurian Region:
The most important industrial area of China is in Manchuria with centres at Anshan (steel industry), Penki (steel industry), Fushun (coal, lubricating oil, and chemicals), Mukden or Shenyang (machinery and tools) and Dairen (mills and shipyards) – all of them near coal and iron ore deposits. Anshan, Fushun and Shenyang form a triangle, within which are numerous large plants.
Here, China developed the largest coal mine, by far the largest blast furnaces and almost the only important steel mills, major factories for railway equipment, cement plants, chemical works, military arsenals and factories for the processing of agricultural products. This was principally an area of heavy industry.
Tientsin and Beijing Region:
A second industrial area has been developed at the northern end of the North China Plain, near the Kailan coal reserves, with Tientsin, Peking or Beijing and Tangshan as its main centres.
This industrial complex centred on Tientsin and extending from Chinwang to southward along the coast past Kaiping, Tangshan and Tangshu, and thence westward beyond Beijing. The presence of coal-fields in Shansi and Hopei has contributed to the rise of the metallurgical and engineering industries here.
Beijing, Tientsin and Tangshan produce coal, steel and machinery making this northern region the industrial centre for the whole of the North China Plain. The industrial economy of the area has much in common with that of Manchuria.
Lower Yangtze Industrial Region:
This is China’s oldest industrial region because the area has been open to foreign influence since the middle of 19th century. Shanghai is the main industrial town and port of this industrial region. This is an area for the production of consumer goods such as cotton, silk, textile, food, leather, radio, television sets, utensils, leather, etc. Shanghai’s population has now increased rapidly.
The needs of the city and its productive hinterland led to factories being set up, partly supplied from overseas; these produced foodstuffs and included flour and oil mills. Paper and tobacco factories were also established, and later the first machine repair shops, from which the present-day iron steel and machines industry has developed.
The cotton textile mills of Shanghai industrial region are some of the largest in Asia. Shanghai and the lower Yangtze Delta area clearly lead in total industrial output. There are also shipyards, oil refineries, flour mills, steel plants, metal works and a great variety of light industrial products.
The Middle Yangtze Industrial Region:
The industrial centre furthest inland was the one on the middle Yangtze plain around the former tripartile town of Hankow-Hanyang-Wuhan, with the river navigable for large ocean going vessels up to that point. The iron and steel works here are based on Peninsiang coal and Tayeh iron ore. Shipbuilding, metallurgical and heavy industries, railway equipment and chemicals are important items of production.
Yangtze forms a magnificent waterway, being navigable for large ocean vessels nearly 1,600 km from its mouth. The next important town is Hanyang. Hanyang lies not far from coal and iron ore deposits and was in fact the cradle of China’s heavy industry. Engineering and textile works were later set up, together with foodstuffs factories.
Sichuan (Szechwan) Industrial Region: Sichuan (Szechwan) province above the Chang Jian (Yangtze Kiang) gorge has many important industries around Chongqing (Chungking) and Chengdu (Chengtu).
The rich deposits of coal, iron, ferro-alloys and abundant agricultural raw materials have all encouraged industrial development. Iron and steel, textiles, paper and pulp, machinery, cement, and chemicals are made here.
Si Kiang Delta Region:
At the mouth of the Xi Jiang (Si Kiang) the port of Canton is the main industrial centre. Canton lacks local raw materials and once was known largely for commerce. Modern industries are centred on silk production; there are silk mills, jute and cotton goods are manufactured, rubber is processed, and there are food-canning and match factories. Iron works and machine factories occupy sites near the docks.
The iron ore comes from Hainan Island. There are also mechanised porcelain factories. But, in spite of Cantons many industries; it is firstly a trading centre for the exchange of goods between the interior and countries overseas.
Food processing factories have recently been established at Swatow. Next along the coast come the towns adjacent to Canton-Fatshan which produces textiles and household goods, Shuntak (for silk and sugar), Tungkuan (sugar and food) industries.
Japanese industrial regions
Japan is the highly industrialized country of Asia. Despite its shortage in industrial raw materials and solid fuel, it has been able to develop industries at a very fast rate.
The reasons of rapid industrial growth in Japan are:
· Availability of hydroelectric power.
· Coastal location and large ports which helps in import of raw material and also in export.
· Proximity to mainland of Asia providing a ready market. Now, Japan has a worldwide market for its products.
· Country’s large population provides a ready source of labour.
· Technological development.
· Government encouragement, etc.
Tokyo-Yokohama Region:
The greatest industrial region of Japan is the Kwanto plain and is formed by the conurbation of three chief cities, Tokyo, Kawasaki and Yokohama. Tokyo the capital of the country, is favourably situated in the middle of a small fertile plain known as Kwanto plain, and carries on many artistic industries.
Tokyo is noted for electrical engineering such as transistors, radio television sets, washing machines, refrigerators and computers. Today, it ranks high in blast furnaces, steel mills, machines and tools, chemicals, refineries, shipbuilding, airplane, factories of consumer goods, electrical machinery, textile and canning indus¬tries, etc.
Yokohama is a port city where manufacturing has been overshadowed by trade. One reason for the slower development of industry has been restricted area of level land suitable for the expansion of factory sites. Yokohama has precision engineering, shipbuilding, oil refining, petrochemicals and port industries.
The third industrial city is Kawasaki. Its Heavy Industries Ltd., Japan’s top manufacturer of industrial robots, is planning to bolster production and step up sales, including those in Europe and the USA to meet the growing demand.
Though about 90 per cent of robots it makes at present are arc welders for sale to car manufacturers. It will be placing heavier emphasis from now on to the output of robots for other purposes, such as spray painting and assembling.
Osaka, Kobe and Kyoto Region:
In the Hanshin or Kinki region are three of the Japan’s six great cities – Osaka, Kobe and Kyoto, the first two of which are also among the three great deepwater ports. The manufacturing structure of the Hanshin region is one of great diversity.
Until recently at least, textiles lead all other industries. The cotton industry is carried on chiefly at Osaka and other towns in the fertile plain that borders the northern shore of the inland sea.
Osaka is the greatest cotton-textile town and is generally known as the Manchester of Japan. Here the naturally dense population makes labour cheap, and affords a good market. As Osaka has just one poor harbour, it is largely served by the port of Kobe.
The Osaka-Kobe industrial region is as smoky, noisy and unattractive in appearance as are most regions of heavy industry. Kobe concentrates on shipbuilding, oil refining, and petrochemical industries including synthetic textile and rubber manufacture.

The Nagoya Industrial Region:
The third industrial region of Japan is Nagoya. Nagoya has textile mills that process local silk, imported cotton and also synthetic fibres; engineering indus¬tries, including all kinds of machinery automobiles, locomotives and aircraft.
Textile, including silk reeling, cotton spinning, cotton weaving and wool weaving lead all other industries. Much of Nagoya’s woollen industry is relatively new and Australian wool is chiefly used. Nagoya is one of the country’s foremost aircraft manufacturing centres.
Northern Kyushu Region:
This industrial region is located close to the south-western limit of the general manufacturing belt in northern Kyushu. It ranks 4th among the manufacturing concentrations, being credited with nearly 90 per cent of the nation’s industrial output.
Chikuho coalfield is situated in close proximity of this heavy industrial centre. Textiles are not an important element of the industrial structure of this region; of first importance are the heavy industries, especially iron and steel manufacturing.
Yumata, Kokura, Moji, Fukuoka are the industrial centre of this region. Outside the above four major industrial regions there are several scattered industrial towns. Iron and steel is made at Muroran; oil refining is important at Akita and Niligata; engineering at Hiroshima; shipbuilding at Kure; textiles at Okayama. Hakodate and Sapporo in Hokkaido also have some industrial development.

Important Industrial Regions of Europe
Manufacturing Centers in Western Europe
The major manufacturing centers in Western Europe extend in a north-south band from Britain to Italy. Rhine—Ruhr Valley –Transportation- This location at the mouth of Europe’s most important river has made Rotterdam the world’s largest port. –Proximity to Raw Materials- Iron and steel manufacturing has concentrated in the Rhine—Ruhr Valley because of proximity to large coalfields. This has resulted in major automotive and machinery manufacturing plants. –Labour Supply- proximity to large cities provides lots of available labourers
Industrial revolution was first started in Europe, with the result heavy industries on a large scale have developed in many parts of the Europe.
In spite of industrial development in many regions of the world, Europe is still a great industrial power. In Europe, industries are distributed in many countries and the manufacturing belt of Europe is not continuous.
The principal manufacturing zone extends from west to east, from Britain through north-eastern France, Belgium, the Rhineland of West, Germany, and Saxony-Bohemia to Silesia. Other important industrial areas are found on the Swiss Plateau, northern Italy, in central Sweden and in many large towns and cities throughout Europe such as London, Paris, Berlin and Milan
The place of Europe‘s primary industrial regions still reflects the spatial diffusion of the Industrial Revolution. An axis of manufacturing extends from Britain to Poland and the Czech Republic, and onward to Ukraine. The explanation of this pattern lies in the place of coal fields in Britain and the European continent. Britain‘s coal fired industries produced a pattern of functional specialization that, for a time, had no equal in the world, for it was coal that fired the Industrial Revolution. Europe‘s coal deposits lie in a belt across northern France, Belgium, north-central Germany, the northwestern Czech Republic, and southern Poland—and when the Industrial Revolution diffused from Britain onto the mainland it was along this zone that Europe‘s major concentrations of heavy industry developed. Europe‘s industrial success also depended on the skills of its labor force and the high degree of specialization achieved in various industrial zones.

United Kingdom:
UK was the first country in the world to become highly industrialized. Most of its industrial regions are closely associated with the coalfields. At the present time industry is declining due to cheaper and more efficient production overseas, and with old equipment and labour troubles at home. But still the industrial structure of UK is considered important
The North-East Coast:
The north-east coast industrial region also accords fairly closely with a coalfield, that of Durham and Northumberland. Again the basic industries are coal mining and iron and steel production. Its economic fortunes have not differed greatly from those of West Cumberland in recent years, though a greater variety of steel processing industries and also other industries, such as chemicals, have been established.
Foremost amongst these is the shipbuilding industry of the Tyne. Marine, mechanical and constructional engineering are also relatively important. The chemical industries have recently assumed great importance at Birmingham.
Cumberland and Westmorland:
This region occupies very approximately the coalfield that lies between the Lake District hills and the sea. It is a less specialized region. Apart from coal mining, now of declining importance, iron and steel production is the principal industry.
The West Riding of Yorkshire:
This district is dominated by the manufacture of woolen and worsted cloth. Second in importance comes coal mining and iron and steel production. In general, the former occupies the more northerly valleys, centered on Leeds, and the latter, the more southerly, with their focus in Sheffield.
The West Riding, unlike the two regions already mentioned, has attracted a large number of subsidiary industries — those which absorb the by-products or work up the main products of the principal industries and those which serve the needs of the large industrial population.
Nottinghamshire and Derbyshire:
These counties contain the southern extension of the West Riding coalfield. Here the woollen industry gives way to hosiery, which has, in large measure, replaced the ancient lace industry. Coal mining remains important and many branches of the engineering industry are carried on.
Railway and motor engineering, the manufacture of cables, rayon, heavy chemicals and pharmaceutical goods are amongst the products of this area which must count as one of the most varied industrial regions of the country.
The Birmingham Region (Midlands):
The Birmingham region is now much more extensive than the coalfields of South Staffordshire and Warwickshire from which it grew. It is impossible to point to any predominant industry, though the manufacture of motor cars is one of the most important.
Greater London:
This region has the greatest variety of industry to be found in any industrial region in Great Britain. None is basic or fundamental to the area in the sense that it could not be carried on equally well elsewhere. Most are concerned with the manufacture of consumer goods; furniture, ready-made clothing, musical instruments, patent and prepared foods.
South Wales:
A region of coal and steel, South Wales has been in recent years as depressed as similar areas in the north of England.
Scotland:
Central Scotland contains a number of coalfields and on these local resources a number of varied textile, metallurgical and engineering industries have been built up. The most important concentrations within this region are on the Clyde
Germany:
Rhine Industrial Region:
This region is also known as ‘Ruhr-Westphalia Industrial Region’. This region is not only a prominent industrial region of Germany but also that of Europe. In this region, coal of high quality is available from Ruhr coalfield.
The Middle Rhine Industrial Region:
The widely spread industrial complex at the confluence of the Rhine and the Main rivers enjoys the advantages of easy water transport, and convergence of rail and road routes. Frankfurt is a railway engineering centre with electrical engineering, automobile and chemicals industries. Mainz has leather, brewing, and engineering industries.
The Hamburg Industrial Region:
Hamburg is not a region but a metropolitan city. Here also specialized industries have developed to a great extent. Among the industries, notable are ship-building, light chemicals, tobacco, non-ferrous industries, petro-chemical, and petroleum refining and engineering industries.
The Berlin Industrial Region:
West Berlin was developed as a major industrial centre under West German occupation. It was the capital of undivided Germany and derived advantage as a seat of administration. Most of the industrial products contributed by this region are of non-conventional type, including electrical, electronics, cosmetics, light chemicals and precision engineering.
Lipzig Industrial Region:
Leipzig is an industrial town located in the eastern part of Germany. This region is famous for the production of optical instruments, leather products, engineering goods and machine tools.
France:
France is the third industrial country in Europe. The major industrial regions of the France are as follows:
Lorraine Industrial Region:
The Lorraine since before World War I has contributed to the France’s economy some two-thirds of total steel and more than three-fourths of total pig iron production. This region is, therefore, recognised as the single most important centre for such manufacturing.
The Lorraine iron and steel plants are grouped in three areas. Outstanding among these is the Metz-Thionvill complex in the Mosselle valley.The second area is the Longway-Villerapt area near the Belgium Luxembourg border, often referred to as the Northern district. This area produces one-third of Lorraine’s iron and steel production.
The third area is Nancy. Nancy has large iron and steel works. The best supplies of iron in the country are found in the basin of the Mosalle.
The Greater Paris Basin:
The capital of France has naturally arisen in the midst of this productive area, and at the best centre of the system of waterways formed by the Seine and its tributaries. Small sea-vessels can reach Paris, and the trade of its port is considerable; but it is not a great manufacture town, and suffers from lack of coal in the vicinity.
Rhone Valley Region:
The water of the Rhone is, moreover, suited for dyeing the silk. The silk industry is also carried on at Avignon, on the Rhone near the confluence of the Durance and at Nimes, to the west.
Mediterranean Industrial Region:
The Mediterranean seaboard of France, west of Marseilles is marshy but east of Marseilles it is extremely picturesque, and warm enough for even oranges and lemons in parts. Marseilles carries on an enormous trade with other Mediterranean ports, and with southern Asia by way of the Suez Canal. Among its industries is the manufacture of soap (which is fostered by the good local supply of olive oil), chemicals, paper and pulp, sugar, leather, silk industry and ship repairing.
Italy:
In Italy industrial development began only after the Second World War. The two distinct industrial regions of Italy are northern and southern regions. The Northern Region: About four-fifths of the industries is concentrated in Northern Italy. The major industrial regions are Lombardy, Piedmont, Liguria, etc. Most of the manufacturing units are concentrated in urban centers, The Southern Region: This region is far less developed in manufacturing than its northern counterpart. Naples is the only major industrial centre, having textiles, machinery and, iron and steel plants.
Other European Industrial Regions:
Belgium has heavy industries, including iron and steel making and the manufacture of armaments. Liege, Brussels, Antwerp, and Ghent, are the major industrial centers of Belgium. The Netherlands has 40 per cent of its population engaged in the industrial sector Sweden is the most industrialized country. The main industrial region is in central Sweden, the so-called Lake Depression, with its main centre at Stockholm. Sweden has the richest iron ore resources of Europe, has developed much hydroelectric power and has a long history of technological skills. Norway’s leading industries are marine engineering, shipbuilding, fish-canning and the pulp and paper industries.
Denmark is famous for its dairying and agricultural industries. Other industries developed in Denmark are chemicals, textiles fishing vessels, beer, silverware, machinery, electric equipments, etc. Switzerland, although a mountainous region, is famous for watch-making, engineering, chemicals and textiles. The Swiss Plateau has the greatest concentration of industrial plants. Poland is having an important industrial region in south of the country. Iron and steel, chemicals, textiles and zinc/lead refining are important industries developed in this region.
Manufacturing Centers in Eastern Europe
Russian Federation.
The Moscow-Tula Industrial Region:
The largest concentration of industries occurs within Moscow-Tula region. Major industries are iron-steel, heavy chemical, metallurgy, machine tools, refineries, textile, electrical, automo­bile etc. This industrial agglomeration produces nearly one-fourth of the national industrial output.Gorky and Lipetsk produce high quality steel and heavy engineering products. The cities of Yaroslav and Lipetsk produce agricultural machinery and electronics, respectively. Ivanovo and Yaroslav cities produce aluminium and other metallurgical products. Moscow-Tula-Vladimir triangle produces huge amount of textile goods. Ivanovo attained such a high fame in textile production that it became famous as ‘Manchester of CIS’.

The Ural Industrial Region:
The development of Ural industrial region owes much to the huge iron ore deposits of Magnitogorsk, Nizhny Tagil and Serov. After the initiation of Communist regime, development of Ural received priority and for rapid industrialization of the region ‘Ural-Kuznetsk Combine’ was constructed. According to the plan, a symbiotic or reciprocal relationship was established between Ural and Kuznetsk region. Ural iron ores sent to Kuznetsk, in lieu of Kuznetsk coal.
Large iron-steel centres were developed at Nizhniy Tagil, Sverdlovsk, Serov, Chelyabinsk, Magnitogorsk and Orsk etc. After the discovery of Karaganda coal reserve, this system was to some extent modified. This region has a very good communication system, specially railroads. Gradually several other industries developed. Among these, machine tools, agricultural machinery, chemicals etc. are important.
The Volga Industrial Region:
The development of manufacturing activities is a com­paratively recent phenomena in Volga region. Even in the first phase of Communist regime, industrialization in Volga region took place at a slow pace. The Tartar oilfield and Kuybyshev oilfields helped to develop industrial base at Volga valley. Kuybyshev-Kazan and Volgograd are the most important industrial centres having chemical and machine tool plants.
The Kuznetsk Industrial Region:
The once deserted and sparsely populated region of Kuznetsk basin is now having sprawling industrial township having large number of industries, of which iron-steel is most important. The exploration of vast amount of coal reserve and subsequent development of Ural-Kuznetsk combined system, which provides iron ore of Ural to Kuznetsk in lieu of coal, helped great development of iron-steel industry here.
The Southern Industrial Region:
The great Ukraine region is the greatest industrial area in CIS. This area contributed largest amount of iron-steel and other metallurgical products. The famous Donetsk coal and Krivoi Rog iron ore was the basis for the overall economic and industrial growth of the region. Besides this, Nikopol manganese is also used widely in iron- steel industry. Zaparzhye limestone is another raw material found in the region.
The two large plants, one each at Donbas and Krivoi Rog, provided necessary infrastructure to other indus­tries. The symbiotic growth between Donetsk coal and Krivoi Rog iron ore or ‘combine’ is the fundamental principle, first adopted here. The other precision manufacturing units are situated at Odessa and Zaparzhye. The other industrial centres are Konstantinovka, Zhdanov.
Caucasus Industrial Region:
This region is famous for the manufacturing of heavy chemical industries. The discovery of enormous amount of crude oil within the region also helped to establish refineries and petro-chemical industries at Baku, Grozny, Maikop and Batum. The other noted centres were developed at places like Tbilisi, Kirovakam and Sumgait.
Various coal based industries developed in places like Kemerovo, Osirniki etc. Great development of iron-steel industry occurred in Novokuznetsk, Nosibirsk and several other places. Machine tools, textile and chemical industries were also developed in this region.

Biosphere and Biomes

The biosphere is made up of the parts of Earth where life exists. The biosphere extends from the deepest ocean trenches, to lush rain forests and high mountaintops. The Earth can be described in terms of spheres. The solid surface layer of the Earth is the lithosphere. The atmosphere is the layer of air that stretches above the lithosphere. The Earth’s water—on the surface, in the ground, and in the air—makes up the hydrosphere. Since life exists on the ground, in the air, and in the water, the biosphere overlaps all these spheres. Although the biosphere measures about 20 kilometers (12 miles) from top to bottom, almost all life exists between about 500 meters (1,640 feet) below the ocean’s surface to about 6 kilometers (3.75 miles) above sea level.

The Biosphere can be divided in to much smaller Biomes : Aquatic ecosystem

Aquatic ecosystem

An aquatic ecosystem is a specific type of ecosystem found within bodies of water, encompassing both the plants and animals that inhabit these areas. Covering approximately 70 percent of Earth’s surface, aquatic ecosystems are classified into two main categories: saltwater and freshwater. Saltwater ecosystems, such as oceans and coral reefs, have high salinity and feature diverse habitats including intertidal, pelagic, benthic, and abyssal zones, each supporting unique biological communities. Freshwater ecosystems, which include lakes, rivers, and wetlands, are characterized by low salt concentrations and contain varying habitats, such as the warm littoral zone and the deeper, colder profundal zone.

Life Forms of Aquatic Biomes

Neuston :

Neuston are aquatic organisms living at the surface air-water interface. These unattached organisms include bacteria, algae, protozoa, insects, and larger animals like sea snails and jellyfish. They rely on surface tension, utilize the interface as a habitat, and face threats from pollution and climate change.

Types of Neuston

Epineuston: Organisms that live on the water’s surface.
Hyponeuston: Organisms that live just below the surface layer.

Plankton

Plankton consist of any drifting organisms (animals, plants, archaea, or bacteria) that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. They provide a crucial source of food to aquatic life. The name plankton is derived from the Greek word “planktos”, meaning “drifter”. While some forms of plankton are capable of independent movement and can swim up to several hundreds of meters vertically in a single day , their horizontal position is primarily determined by currents in the body of water they inhabit. By definition, organisms classified as plankton are unable to resist ocean currents.

This is in contrast to nekton organisms that can swim against the ambient flow of the water environment and control their position. (e.g. squid, fish, and marine mammals).

  • Picoplankton (.2-2 µm) bacterioplankton
  • Nanoplankton (2 – 20 µm) protozoans
  • Microplankton (20-200 µm) diatoms, eggs, larvae
  • Macroplankton (200-2,000 µm) some eggs, juvenile fish
  • Megaplankton (> 2,000 µm) includes jellyfish, ctenophores, Mola mola

    Zooplankton are the heterotrophic (sometimes detritivorous) component of the plankton that drift in the water column of oceans, seas, and bodies of fresh water. Many zooplankton are too small to be individually seen with the unaided eye.

    Zooplankton is a broad categorisation spanning a range of organism sizes that includes both small protozoans and large metazoans. It includes holoplanktonic (copepods, salps, and some jellyfish)organisms whose complete life cycle lies within the plankton, and meroplanktonic(sea urchins, starfish, crustaceans, marine worms, and most fish) organisms that spend part of their life cycle in the plankton before graduating to either the nekton or a sessile, benthic existence.

    Mode of life:

    Holoplankton spends entire lifecycle as plankton Ex. Jellyfish, copepods

    Meroplankton spend part of lifecycle as plankton Ex. fish and crab larvae, eggs

    Nutritional modes of zooplankton:

    Herbivores: feed primarily on phytoplankton • Carnivores: feed primarily on other zooplankton (animals)

    Detrivores: feed primarily on dead organic matter (detritus)

    Omnivores: feed on mixed diet of plants and animals and detritus

    Zooplanktons are always dominated by two major groups of animals such as protozoa, metazoan

    Ecologically important protozoan zooplankton groups include the foraminiferans, radiolarians and dinoflagellates. Important metazoan zooplankton include cnidarians such as jellyfish and the Portuguese Man o’ War

    • Crustaceans such as copepods and krill;
    • Molluscs such as pteropods; and
    • Chordates such as salps and juvenile fish
  • Nektonic feeding types
  • Of the nektonic feeding types, zooplankton feeders are the most abundant and include, in addition to many bony fishes, such as the sardines and mackerel, some of the largest nekton, the baleen whales. The molluscs, sharks, and many of the larger bony fishes consume animals bigger than zooplankton. Herbivorous nekton are not very common, although a few nearshore and shallow-water species subsist by grazing on plants.

    Nektonic feeding types

Ecological Succession

Biogeochemical cycles, also known as nutrient cycles, describe the movement of chemical elements through different media, such as the atmosphere, soil, rocks, bodies of water, and organisms. Biogeochemical cycles keep essential elements available to plants and other organisms. The biogeochemical cycles of four elements—carbon, nitrogen, phosphorus, and sulfur—are discussed below. The cycling of these elements is interconnected with the Water Cycle For example, the movement of water is critical for the leaching of sulfur and phosphorus into rivers, lakes, and oceans.

The Carbon Cycle Carbon is the basic building block of all organic materials, and therefore, of living organisms. The carbon cycle is actually comprised of several interconnected cycles: one dealing with rapid carbon exchange among living organisms and the other dealing with the long-term cycling of carbon through geologic processes.

Carbon dioxide in the atmosphere is converted to organic carbon through photosynthesis by terrestrial organisms (like trees) and marine organisms (like algae).

Respiration by terrestrial organisms (like trees and deer) and marine organisms (like algae and fish) release carbon dioxide back into the atmosphere. Additionally, microbes that decompose dead organisms release carbon dioxide through respiration.

Weathering of terrestrial rocks also brings carbon into the soil. Carbon in the soil enters the water through leaching and runoff. It can accumulate into ocean sediments and reenter land through uplifting. Long-term storage of organic carbon occurs when matter from living organisms is buried deep underground and becomes fossilized. Volcanic activity and, more recently, human emissions stored carbon back into the carbon cycle.

The Nitrogen Cycle

All organisms require nitrogen because it is an important component of nucleic acids, proteins, and other organic molecules. Getting nitrogen into living organisms is difficult. Plants and algae are not equipped to incorporate nitrogen from the atmosphere (where it exists as tightly bonded, triple covalent N2) although this molecule comprises approximately 78 percent of the atmosphere. Because most of the nitrogen is stored in the atmosphere, the atmosphere is considered a reservoir of nitrogen.

In the nitrogen cycle, nitrogen-fixing bacteria in the soil or legume root nodules convert nitrogen gas (N2) from the atmosphere to ammonium (NH4+).

  • Nitrification occurs when bacteria convert ammonium to nitrites (NO2-) and then to nitrates (NO3-). Nitrates re-enter the atmosphere as nitrogen gas through denitrification by bacteria.
  • Plants assimilate ammonium and nitrates, producing organic nitrogen, which is available to consumers.Three processes are responsible for most of the nitrogen fixation in the biosphere. 
  • Decomposers, including aerobic and anaerobic bacteria and fungi, break down organic nitrogen and release ammonium through ammonification.
    • The first is atmospheric fixation by lightning. The enormous energy of lightning breaks nitrogen molecules and enables their atoms to combine with oxygen in the air forming nitrogen oxides. These dissolve in rain, forming nitrates, that are carried to the earth. Atmospheric nitrogen fixation probably contributes some 5-8% of the total nitrogen fixed.
    • The second process is industrial fixation. Under great pressure, at a temperature of 600°C (1112°F), and with the use of a catalyst (which facilitates chemical reactions), atmospheric nitrogen and hydrogen can be combined to form ammonia (NH3). Ammonia can be used directly as fertilizer, but most of it is further processed to urea and ammonium nitrate (NH4NO3).
    • The third process is biological fixation by certain free-living or symbiotic bacteria. Some form a symbiotic relationship with plants in the legume family, which includes beans, peas, soybeans, alfalfa, and clovers . Some nitrogen-fixing bacteria even establish symbiotic relationships with animals, e.g., termites and “shipworms” (wood-eating bivalves).

    Nitrogen-fixing cyanobacteria are essential to maintaining the fertility of semi-aquatic environments like rice paddies. Although the first stable product of the process is ammonia, this is quickly incorporated into protein and other organic nitrogen compounds.

Ammonium is converted by bacteria and archaea into nitrites (NO2−) and then nitrates (NO3−) through the process of nitrification. Like ammonium, nitrites and nitrates are found in water and the soil. Some nitrates are converted back into nitrogen gas, which is released into the atmosphere. The process, called denitrification, is conducted by bacteria. Plants and other producers directly use ammonium and nitrates to make organic molecules through the process of assimilation. This nitrogen is now available to consumers. Organic nitrogen is especially important to the study of ecosystem dynamics because many processes, such as primary production, are limited by the available supply of nitrogen. Consumers excrete organic nitrogen compounds that return to the environment. Additionally dead organisms at each trophic level contain organic nitrogen. Microorganisms, such as bacteria and fungi, decompose these wastes and dead tissues, ultimately producing ammonium through the process of ammonification.

The Phosphorus Cycle Several forms of nitrogen (nitrogen gas, ammnoium, nitrates, etc.) were involved in the nitrogen cycle, but phosphorus remains primarily in the form of the phosphate ion (PO43-). Also in contrast to the nitrogen cycle, there is no form of phosphorus in the atmosphere. Phosphorus is used to make nucleic acids and the phospholipids that comprise biological membranes.

Phosphate enters the atmosphere from volcanic aerosols, which precipitate to Earth. Weathering of rocks also releases phosphate into the soil and water, where it becomes available to terrestrial food webs. Some of the phosphate from terrestrial food webs dissolves in streams and lakes, and the remainder enters the soil. Phosphate enters the ocean via surface runoff, groundwater flow, and river flow, where it becomes dissolved in ocean water or enters marine food webs. Some phosphate falls to the ocean floor where it becomes sediment. If uplifting occurs, this sediment can return to land.

The Sulfur Cycle Sulfur is an essential element for the molecules of living things. As part of the amino acid cysteine, it is critical to the three-dimensional shape of proteins.

Atmospheric sulfur is found in the form of sulfur dioxide (SO2), which enters the atmosphere in three ways:

  • first, from the decomposition of organic molecules;
  • second, from volcanic activity and geothermal vents; and,
  • third, from the burning of fossil fuels by humans.

Sulfur dioxide (SO2) from the atmosphere is dissolved in precipitation as weak sulfuric acid or falls directly to Earth as fallout. This releases sulfates (SO42-) into the soil and water. Soil sulfates can be carried as runoff into the water. Marine sulfate can form pyrite, and this can break down to release soil sulfates.

Organisms in terrestrial and marine ecosystems assimilate sulfate, adding sulfur to organic molecules, such as proteins (not shown). Decomposition of these organisms returns sulfates to the soil. Microorganisms can convert sulfates to hydrogen sulfide (H2S) and vice versa. Decomposition, volcanic eruptions, and human activities (including burning fossil fuels) can release hydrogen sulfide (H2S) or sulfur dioxide into the atmosphere.

Ecological succession 

Ecological succession is the gradual and sequential replacement of one community by the other in an area over a period of time. According to E.P. Odum (1971), the ecological succession is an orderly process of community change in a unit area. It is the process of change in species composition in an ecosystem over time.

Process of Ecosystem Succession The ecological succession is a complex process and it may take thousands of years. Frederic Clements in 1916 for the first time proposed the sequential phases of an ecological succession.

Different Types of Ecological Succession

Primary succession is initiated when a new area that has never previously supported an ecological community is colonized by plants and animals. This could be on newly exposed rock surfaces from landslides or lava flows.

Secondary succession occurs when an area that has previously had an ecological community is so disturbed or changed that the original community was destroyed and a new community moves in. This is more common than primary succession and is often the result of natural disasters, such as fires, floods, and winds, as well as human interference, such as logging and clear-cutting.

Stages of Succession

Nudation/Bare Area: The creation of a lifeless area, whether from a disturbance or new habitat formation.

Migration: The dispersal of seeds, spores, and other propagules from existing communities into the bare area by wind, water, or animals.

Ecesis: The successful establishment and growth of the colonizing species as they adapt to the new environment.

Aggregation: The growth in population of these initial species, leading to a denser and more complex community.

Competition and Co-action: As populations grow, species begin to interact and compete for resources, influencing the community’s structure.

Reaction: The development of new environmental conditions by the existing community that may hinder its own survival but facilitate the establishment of new species.

Stabilization/Climax Community: A stable, mature community that is relatively well-adapted to its environment, with high biodiversity and a balanced species composition.

Ecosystem Functions

Photosynthetic and Chemosynthetic organisms

Photosynthetic and chemosynthetic organisms are autotrophs, which are organisms capable of synthesizing their own food (more specifically, capable of using inorganic carbon as a carbon source).

Photosynthetic autotrophs (photoautotrophs) use sunlight as an energy source, and chemosynthetic autotrophs (chemoautotrophs) use inorganic molecules as an energy source. Autotrophs are critical for ecosystems because they occupy the trophic level containing producers. Without these organisms, energy would not be available to other living organisms, and life would not be possible.

Photoautotrophs, such as plants, algae, and photosynthetic bacteria, are the energy source for a majority of the world’s ecosystems.

Photoautotrophs harness the Sun’s solar energy by converting it to chemical energy.

Chemoautotrophs are primarily bacteria and archaea that are found in rare ecosystems where sunlight is not available, such as those associated with dark caves or hydrothermal vents at the bottom of the ocean . Many chemoautotrophs in hydrothermal vents use hydrogen sulfide (H2S), which is released from the vents, as a source of chemical energy. This allows them to synthesize complex organic molecules, such as glucose, for their own energy and, in turn, supplies energy to the rest of the ecosystem.The feeding positions in a food chain or web are called trophic levels. The different trophic levels are defined in the Table below. Examples are also given in the table. All food chains and webs have at least two or three trophic levels. Generally, there are a maximum of four trophic levels.
Many consumers feed at more than one trophic level. Humans, for example, are primary consumers when they eat plants such as vegetables. They are secondary consumers when they eat cows. They are tertiary consumers when they eat salmon.

Trophic Levels

The feeding positions in a food chain or web are called trophic levels. The different trophic levels are defined in the Table below. Examples are also given in the table. All food chains and webs have at least two or three trophic levels. Generally, there are a maximum of four trophic levels. Many consumers feed at more than one trophic level. Humans, for example, are primary consumers when they eat plants such as vegetables. They are secondary consumers when they eat cows. They are tertiary consumers when they eat salmon.

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