Search results
Population Growth Rate. Population growth rate (r) is how fast a population changes in size over time. A positive growth rate means a population is increasing. A negative growth rate means it is decreasing. The two main factors affecting population growth are the birth rate (b) and death rate (d).
The population growth rate (sometimes called the rate of increase or per capita growth rate, r) equals the birth rate (b) minus the death rate (d) divided by the initial population size (N 0). Another method of calculating the population growth rate involves final and initial population size (figure 5.3.a 5.3. a).
- Overview
- Calculating population growth
- Population dynamics
- Human population growth
population growth, in population ecology, a change in the number of members of a certain plant or animal species in a particular location during a particular time period. Factors affecting population growth include fertility, mortality, and, in animals, migration—i.e., immigration to or emigration from a particular location. The average change in a...
Population growth rates in a given location and time period can be calculated by subtracting population loss, or the combined rates of mortality and emigration, from population gain, or the combined rates of fertility and immigration. Fertility is the number of offspring produced on average by an individual species member under certain environmenta...
The natural environment plays a crucial role in population growth through its carrying capacity. The life-sustaining resources in an environment are limited and can be reduced for individual species members by greater population density and competition from other species, among other factors. Moreover, fertility, mortality, and migration are all affected by food availability, mate availability, and environmental stress factors such as pollution and natural disasters.
Population growth dynamics may be graphically depicted in an S-shaped curve, known as a logistic curve, as depicted in Figure 1. The logistic curve (right) represents an initial lag in growth, a burst of exponential growth, and finally a decline in population growth. When population density is high, mortality tends to increase because of competition for resources, predation, or increased disease transmission, resulting in the plateau in growth at the end of the curve. Population growth rates may also fluctuate in correlation with seasonal variations in the environment. For example, in deep lakes, a spring thaw causes colder, deeper waters to rise to the lake’s surface, releasing nutrients that then cause bursts in the growth of plankton, including algae, bacteria, and protozoans (see water bloom).
The world’s human population experienced exponential growth from the 18th century, but growth rates have been declining since the second half of the 20th century. Although population growth rates vary significantly between countries and some regions continue to experience increasing growth rates, the overall rate of growth is decreasing.
Exclusive academic rate for students! Save 67% on Britannica Premium.
Learn More
The world’s human population reached 8 billion in November 2022 and is predicted to peak at 10.4 billion by 2080 and to remain at that level until the end of the century. Although human mortality rates have been decreasing on average, the main reason for the decreasing population growth rate is lower fertility. Fertility varies based on reproductive behaviour patterns, which in turn depend upon factors such as cultural traditions, socioeconomic conditions, access to contraception, and ecological variables, such as population density.
The population growth rate (sometimes called the rate of increase or per capita growth rate, r) equals the birth rate (b) minus the death rate (d) divided by the initial population size (N 0). Another method of calculating the population growth rate involves final and initial population size (figure 14.2.2).
Demographics can include any statistical factors that influence population growth or decline, but several parameters are particularly important: population size, density, age structure,...
Population growth rate refers to the speed at which the number of individuals in a population increases over a specific period, often expressed as a percentage. This metric is essential for understanding changes in population size, which can be influenced by factors such as birth rates, death rates, immigration, and emigration.
People also ask
What factors determine how fast a population grows?
How does a population grow?
What is population growth rate?
Which model accurately describes natural populations?
What does a positive growth rate mean?
How do you calculate population growth rate?
population growth: how the size of the population is changing over time. If population growth is just one of many population characteristics, what makes studying it so important?
