Are age-structure diagrams useful in predicting future population trends? Yes, age-structure diagrams allow scientists to determine if the number of individuals likely to have children will increase or decrease in the future. Tells us whether a population is growing, stable, or declining in numbers.

By using an age structure diagram it can be predicted whether a population will increase, decrease or maintain stability. Predictions can also be made as to why this trend is showing for example: is the population decreasing because most of the population is in the post productive age group?

An age-structure diagram provides a snapshot of the current population and can represent information about the past and give potential clues about future problems. When you are interpreting age-structure diagrams, it is important to compare the width of the base to the rest of the population.

The different age-structure diagrams are represented by different shapes. Four general types are the pyramid, column, an inverted pyramid (top-heavy), and a column with a bulge.

It is common in demography to split the population into three broad age groups:

• children and young adolescents (under 15 years old)
• the working-age population (15-64 years) and.
• the elderly population (65 years and older)

Density-dependent factors include disease, competition, and predation. Density-dependant factors can have either a positive or a negative correlation to population size. With a positive relationship, these limiting factors increase with the size of the population and limit growth as population size increases.

Some examples of limiting factors are biotic, like food, mates, and competition with other organisms for resources. Others are abiotic, like space, temperature, altitude, and amount of sunlight available in an environment. Limiting factors are usually expressed as a lack of a particular resource.

Population growth is based on four fundamental factors: birth rate, death rate, immigration, and emigration.

Factors influencing population growth

• Economic development.
• Education.
• Quality of children.
• Welfare payments/State pensions.
• Social and cultural factors.
• Availability of family planning.
• Female labour market participation.
• Death rates – Level of medical provision.

Population growth rate is affected by birth rates, death rates, immigration, and emigration.

1. Greenland. The island nation of Greenland, 80% of which is covered by a massive glacier, is the 12th largest country in the world by area, but the least densely populated.

Overpopulation in China began after World War II in 1949, when Chinese families were encouraged to have as many children as possible in hopes of bringing more money to the country, building a better army, and producing more food.

According to the World Bank, the aging population and low fertility rates are to blame for the increase in population as 36 percent of the world’s population over 65 currently live in East Asia. The World Bank projects that the 211 million people living in East Asia will rise over time.