APHG Vocabulary 2A (Topics 2.1 - 2.3)

Population Distribution

The pattern of where people live across Earth's surface. Population is unevenly distributed because physical factors such as climate, landforms, and access to water, as well as human factors such as economic opportunities, culture, history, and politics, influence where people choose or are able to live.

Population Density

A measurement of the concentration of people within a particular area. Geographers use different measures of population density to compare places and better understand the relationship between population and available land and resources.

Arithmetic Density

The total number of people in an area divided by the area's total land area. Arithmetic density measures the overall concentration of people but does not account for whether all of the land is suitable for settlement or agriculture.

Physiological Density

The total population of an area divided by the amount of arable land available for agriculture. A high physiological density indicates that many people depend on a relatively small amount of farmland and can suggest greater pressure on the land needed to produce food.

Agricultural Density

The number of farmers in an area divided by the amount of arable land. Agricultural density can help geographers understand the efficiency and level of development of agricultural systems; lower agricultural densities are often associated with more mechanized agriculture, while higher densities may indicate greater reliance on human labor.

Arable Land

Land that is suitable for growing crops. The amount and distribution of arable land are important when studying population because populations depend on productive agricultural land for food, and some countries have much less arable land relative to their population than others.

Carrying Capacity

The maximum population that an environment can sustainably support over time with its available resources, such as food, water, land, and energy, without causing long-term environmental degradation or resource depletion.

Resource Availability

The amount and accessibility of natural resources available to support a population. Differences in population density and distribution can create varying levels of pressure on resources such as water, food, land, and energy.

Access to Services

The ability of people to obtain important services such as health care, education, transportation, sanitation, and emergency services. Population density and distribution influence where services are located, how easily people can reach them, and how efficiently governments can provide them.

Infrastructure

The physical systems and facilities that support a population, including transportation networks, water and sewage systems, utilities, and communication networks. Population density and distribution influence where infrastructure is built and the amount of demand placed upon it.

Population Composition

The demographic characteristics that make up a population, particularly its age and sex structure. Geographers analyze population composition to understand differences among places and to anticipate social and economic needs.

Age Structure

The distribution of a population among different age groups. Age structure helps geographers understand whether a population is relatively young, aging, growing, or declining and can indicate future demands for services such as schools, health care, and retirement programs.

Sex Ratio

The numerical relationship between males and females in a population, commonly expressed as the number of males per 100 females. Sex ratios vary among places and age groups because of factors such as birth patterns, mortality, and migration.

Population Pyramid (Age-Sex Structure Diagram)

A graphical representation of a population's age and sex composition, usually displaying males on one side, females on the other, and age groups from youngest at the bottom to oldest at the top. Geographers use population pyramids to assess patterns of population growth or decline and anticipate future social and economic needs.