Population density

See also: Density (homonymy)

The population density can be used to measure any tangible object. However, it is generally applied at living organisms. The population density is generally expressed in terms of objects or organizations per unit of area.

Biological population density

The population density is a current biological measurement and is often used by the guards of nature like a value more suitable than the absolute numbers. Weak densities of population can create a spiral of extinction, where of weak densities lead to an increasingly reduced fertility. This effect is named Effet Gone, according to W.C. Gone which clarified it the first. As example:

  1. Of the problems increased to find partners in the zones of weak density.

  2. an increase in consanguineous unions in the zones of weak density.
  3. a susceptibility to the catastrophic events increased in the zones of weak density.

It should be noticed however that different species will have to the base different densities. For example, the species with strategy R usually have a raised population density, while the Espèces with strategy K can have one population density lower. One weak density of population can be associated with an adaptation towards a specialization in the localization with the reproductive partners, as of pollinating specialized such as one finds some in the family of the Orchidée S.

It is also possible to define the density of a population thanks to its biomass. This method is useful when it is necessary to compare densities of species of very different size or nature.

Human population density

For the human beings, one defines the population density as the number of people per unit of area (which can include or not interior water), although it can also be expressed compared to livable the grounds, inhabited, arable (or potentially arable) or cultivated.

It is frequently expressed as people per square kilometer or per hectare and is obtained simply by dividing the number of people by surface considered measured into square kilometers or hectares.

In practice, one can calculate this for a city, an agglomeration, a country or the whole world.

As example, for the majority of the European countries of important size (integral of this fact of the less populated dense zones and others), the average density oscillates between 100 and 250 inhabitants per square kilometer (France: 94 hab. /km 2 (by counting Guyana), Germany: 231 hab. /km 2 , the United Kingdom: 244 hab. /km 2 ). A ic territory very Désert has as for him a close density, even lower than an inhabitant with the square kilometer (Greenland: 0,03 hab. /km 2 , Maharajahs Western: 1 hab. /km 2 ).

Useful density factor of demographic braking.

The useful density, i.e. per cultivable square kilometer, is one of the many factors which after the level of development, influences anticipations of the families and the States concerning the environment in the broad sense, fruitfulness and thus the population growth. Thus, on level of comparable development, fertility rates and of population growth are generally higher in Africa, America and Oceania that in Eurasia.

Countries and territories densément populated

The countries or territories presenting the higher population densities are:

All these territories share a relatively small surface and an exceptionally high level of Urbanisation, with an urban population economically specialized calling upon external resources agricultural, which illustrates the difference between one population density high and a Surpopulation.

Concerning the States of a certain size, densément populated is the Bangladesh, where 147 million people lives in a highly agricultural zone around the mouth of the Gange, with one population density of more than 1000 inhabitants per km 2 . The population density on the unit of the emerged grounds is at present of 42 inhabitants to the km 2 .

Case of the urban areas

The agglomerations having one population density exceptionally high are often regarded as over-populated, although this depends on many factors such as quality residences and infrastructures or the access to the resources. The densest cities are located in the south and is Asia, although Cairo and Lagos in Africa also fall into this category.

The population of a city however strongly depends on the definition used for the urban area: the densities are higher if one considers only the center of the municipality which if one also counts the suburbs - of more recent development and not yet administratively built-in - as in the concepts of Agglomération or Métropole, this last including neighbouring cities sometimes.

See too

Related articles

List of the countries by population density

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