Population Density: a Simple Concept

Isabel Balmer 12D

Population Density: A Simple Concept?

Population density refers to the number of people in relation to the space occupied by them. The simplest measure, crude density of a population, is the number of people per square kilometre or other unit area and is calculated by:

Total Population

Area of Land Occupied

Calculating the population density can be useful for small units, such as counties or parishes, however it is of no use when applied to national states or continents where internal environmental conditions vary significantly and therefore, the data is inaccurate or misleading. More refined density measures may be calculated; however, even these have problems and inaccuracies.

Many problems exist for geographers trying to establish comparative population densities for different regions. In theory, a population density map should provide a useful starting point for the study of human geography in any area because of the way in which the varying densities of people on the land reflect the relationships between human societies and their environments. Population density maps are graphical illustrations of how and where people live in relationship to the landscape. However, in practice, the physical and environmental features of the landscape and man’s interaction with them are overlooked.

Firstly, there are problems with establishing the number of people in a given area. There are two main ways in which countries such as the UK count their inhabitants: all births, deaths and marriages have been officially recorded since 1837, however, it was not until 1875 that it became an offence for people to fail to register. These records, in theory, would provide an accurate count of the population, but only if the numbers of immigrants and emigrants were also officially registered. Not only is there an unknown number of illegal immigrants, but there is also no accurate record of the number of people leaving the country to settle abroad, (this will apply to other countries apart from the UK) so, although the number of people in a country or given area can be estimated using the official records, it is impossible to tell the exact number.

The second method of counting people and gathering information is by conducting a regular census (in the UK this is every 10 years and has been carried out since 1801, except for 1942 because of the Second World War). Teams of census enumerators are supposed to deliver a census form to every address in the country; however, there are many problems with this:

• May not include people in hospitals, shelters or those who are homeless
• Does not include illegal immigrants
• There are problems for people who are illiterate, or do not speak the country’s language and therefore cannot understand the census form (in the UK, this is solved by issuing various different copies in different languages, or people are sent out to talk to people with disabilities, for example, the blind, but this is very expensive and time consuming and many countries cannot afford it)
• The census may not be returned for various reasons, for example, if someone is not paying tax (although in the UK this is illegal and there is a fine for not returning a census form)
• People may lie, again possibly because they do not want to found, or cross-checked with records (again, in the UK, lying is an offence)
• It may not necessarily be practicable to deliver a census to every known residence, for example, in Australia, there are people who live in very remote areas which are not easily accessible or for which there is no track
• Nomadic people will not be registered, so therefore, it will not be known where they are
• Squatters and people who live in the favelas will not receive a census because it is in the county council’s interest to disown them so that they do not have to provide electricity, fresh water, a sanitary disposal system, roads etc. and also so that the immigrants living in the favelas can do all the jobs that nobody wants to do and get paid a fraction of the minimum wage for that country because they are not registered as part of the country
• Gypsies and New Age Travellers (people with no fixed abode and who do not pay tax) will not receive a census because they are not registered and have no fixed abode so there is no way of knowing where they are anyway
• Censuses go out of date and conducting them every 10 years is not regular enough to account for subsequent demographic changes, for example, internal and external migration
• Censuses are prone to error as they only count the people who are at their residence on the night it is conducted. They exclude visitors and tourists and people who are away from their usual residences, but include students who may be away at college for the night, for example, in 1991, the census taken of London stated that there were 6,679,699 usual residents, however, the following morning, London’s population would have swelled by a further 600,000 commuters from outside the city. These commuters are people who work and spend money in London and use the roads, undergrounds, buses and other services in the city. They also add to the air pollution, litter and possibly crime, so it is argued that these people should be counted as well
• Censuses only give information on where people are at night, but the Government and geographers are also interested in where people are in the day. Some people argue that this is more important because it is when people have the most impact on the environment and interact with the most people
• Census information varies significantly in its accuracy for different parts of the world, for example, people living in mountainous areas that are not easily accessible may not receive a census form, or, LEDCs may not have the money to provide people to go and talk to the illiterate population or those who have disabilities and therefore is not always the most suitable form for effective population mapping
• Censuses (and maps of the world) presume that people stay in the same place and work on that assumption, however, this is not true.

Another problem for geographers trying to establish comparative population densities for different regions is that people cannot be counted as directly comparable units, for example, men and women differ in the amounts of calories they need each day to ensure they stay healthy – men need 2500, whereas women only need 2000 calories, so already it can be seen that in this instance, men have a larger pull on resources. Food requirements also vary for people in different climatic regions; for example, the Inuit will eat food that helps to keep them warm whereas people in warmer climates will not be using the same resources because they do not need to keep warm. People of different ages and different dietary habits will also eat differently and therefore use different resources.

The land element in the population density equation is not as simple as it seems at first sight because there are many problems with the amount of people who live on and farm the land and those that use the resources that come from it for example, population densities of a city are denser than those where the land is mountainous and the relief steep because in the cities there are jobs and employment available, good infrastructure, communications and other services, whereas mountainous land is not easily accessible, there are very limited employment sectors (sheep grazing is mainly all), communication is limited and infrastructure is poor, if any at all. Because of this, there is more reason to live in the cities because a higher standard of living and quality of life is almost certainly guaranteed. A number of measures are used to assess land area, each with a different method and each producing different results.

There are four main methods used to establish the people-land relationship of population density, each with their advantages and disadvantages:

1. The first method uses the total land area in relation to the total population, which is know as arithmetic density. This is the simplest and crudest form of measuring population density as it overlooks the detail of the land and the different densities of people on that land. Even in traditional societies dependant on subsistence agriculture (a form of agriculture where all the produce goes to feed the household and is not for sale) there are technical problems in assessing the total land area, for example, should one include an inter-tidal zone or the sea when assessing the total land are? Some people may argue that it should be included if it is used for produce (sea food or fertile silts) because it is being used as a resource, however, if it were not used, does that area of land have any relevance to or affect the people-land relationship?

Most problems arise from the differences in land quality because a more fertile land will produce more resources and have higher economic value than a low quality land. The differences in land quality are caused by variations in the soil, vegetation, the gradient of slopes (if in fact, there are any slopes at all) and the climate of the area. All these factors affect the quality of the land and if one of these variables in a region is different to another region, the quality of the land will probably be different and therefore, the resources gathered from the land (depending on what the land is used for) will be different.

However, total land area is the easiest source of data for the “land” element of the population density ration. Arithmetic mean is only really useful as a crude generalisation as it does not take into account the distribution of people in relationship to the land.

1. The second measure of calculating the population density is the physiological density. This is calculated by relating the total population to the area of arable land (land cultivated for crops). However, there are problems with this method as well, because it cannot be assumed that all of the population is supported by the area within which it has been counted as the arable land it is being related to may not be producing the resources for that population. In traditional societies, this method may work, for example, subsistence farming, however, the method is invalid in any society which is highly urbanised or dependant on manufacturing and trade because obviously the land cannot be farmed as it is urbanised. It is also most likely that the society is importing most of their resources as the surrounding areas cannot support the numbers of people in the society and that the main trade for the area will be in factories or businesses of some sort.

1. The third method is agricultural density and this method attempts to avoid the above problems, still assuming however, that it is subsistence farming. Agricultural density relates the rural population to the amount of agricultural land it contains, however to many people, to live in a rural area is an attraction and higher quality of life and many of the people living in the area will not farm the land but be commuters to the cities. In China though, many people who live in urban areas have agricultural occupations so because they do not live on the land but only farm it, they are not included in the calculation so the results will be inaccurate (the same goes for including people who live in rural areas but do not farm the land, for example, in the UK and USA). Agricultural density, therefore, is difficult to use in making comparisons between areas with different cultures.

1. The fourth method is called residential density and this is much more useful and accurate for urban areas. Often, the arithmetic method is used to compare the population densities of different cities and how these cities are distributed and factors affecting that, however, for urban areas, it is often more appropriate to relate the total population of, for example, a city, to the amount of land used for residential purposes, therefore, this will not include commercial, industrial and park land or transport networks (i.e. roads). If the quality of life is also an issue, then a better measure may be the number of people per habitable room (the information would be gathered from a census, so the calculation relies on the census information being correct), however, this also cause problems because some families or people may deem a higher quality of life is to have many rooms which in which there is not always a person in, however, other people may prefer to have all of their close relatives living with them. This is sometimes the situation with young or expecting mothers as they may require an extra “hand” to help them with housework and everyday life, in which case, their parents may live with them. Another example is the elderly who need special care or help, so for them, having more people in the house to help them and keep them company would be a higher quality of life. Therefore, it is not so easy to assume that a higher quality of life necessarily means living in a large houses with not many people as different people have varying concepts on what makes their life better.

It can be seen that it is not so easy to just calculate the population density of an area because there are many different factors that affect it. There are also problems when comparing densities with different areas because the factors affecting the densities may be different and this has to be taken into account.

The term carrying capacity is a measure of the number of people an area of land can support before any increase of people brings about worsening conditions or degradation.

The term optimum population, has a similar meaning to carrying capacity, however, it is not the same. Optimum population is the theoretical number of people, which, when working with all the available resources and levels of technology and is therefore getting the most out of the land, will produce the highest standard of living and quality of life. (Standard of living is usually measured by how much a person earns, whereas quality of life is measured by, for example, the person’s surroundings, i.e. rural or urban, the services available and in some parts of the world, whether the person is literate or not.)

The optimum population density is partly down to what society values the most, for example, some people may think that living in a city in a modern and luxurious apartment would increase their quality of life because they are where “life” takes places and in the centre of all the hubbub and parties, whereas, another person may prefer to live in the countryside in a little cottage in a village where there is a strong sense of community spirit and where it is peaceful with very little pollution of any description. How good a person’s quality of life is also depends on their age, for example, a youthful person (20-30) may prefer the city night-life and the atmosphere of a city that never sleeps, whereas an elderly person is more likely to prefer a quiet village which is close to a town or small city where they can use any services they need and get their living needs and any help that they may need because they prefer the rural setting and community spirit of a close-knit community.

Carrying capacity can have an affect on the optimum population density because then an area is over or under populated and therefore not getting the most out of the land economically. (Overpopulation exists where there are too many people in an area relative to the amount of resources and to the level of technology locally available, to maintain a high standard of living. This means, that if there were no change in the level of technology and natural resources locally available, a reduction on the number of people in the area would result in a higher standard of living and, therefore, quality of life. Overpopulation is measured by low per capita incomes, high unemployment and under employment and outward migration.)

Under population occurs when there are too few people in an area to use the available resources and levels of technology efficiently and to the highest economic value. This means, that if the population were to increase then there will be a better use of resources and so an increased standard of living for all the population because the resources are being used to their greatest potential. This would most likely result in a higher quality of life for the whole population.

It should not be assumed, however, that just because one area is successful in supporting a particular density of people (per square kilometre) that another area with a lower density cannot be overpopulated because whether an area is overpopulated or not depends on the quality of the land involved and the resources it has the potential to produce. Also, different people will have different consumer requirements; for example, a Polynesian islander and a farmer in the American Mid-West are very different and therefore, so are the demands they make upon the land, industry and trade. It is also necessary to allow for the differences in the efficiency of people as producers when comparing areas of different cultures as food is not only the requirement of humans and different societies vary in how their economies are self-contained. So far, no general method has been acceptable enough to equate people as producers.