Carrying Capacity — Definition & Overview

What Is Carrying Capacity?

Imagine that you are trying to carry groceries to your kitchen. If you carry too many bags at a time, there's a good chance that one will rip or you will drop a few bags or even fall over due to the extra weight.

The carrying capacity of an environment is a lot like that situation. It's easy for a large forest to support ten deer. Maybe the forest can comfortably carry 100 deer without running out of food and space. But if the forest has to support a million deer, the grass and plants will be eaten to extinction, and the deer will die due to a lack of food.

Many populations live at levels right at the capacity. For example, think of the deer in the forest again. If only ten deer are in the forest, they can eat as much food as they want, stay healthy, and have lots of baby deer. During this time, their population can experience exponential growth.

After a certain point, however, the deer might have to compete for food and space. They might have less baby deer due to fewer resources being available. At this stage, the population will remain at roughly the same size. This is because the deer have hit the carrying capacity of that environment. This same situation applies for human population capacity.

What Is the Opposite of This?

We know now that a carrying capacity determines the number of individuals a given area can support. However, there is also something called an ecological footprint. We use this term to describe the area or resources needed to support a given population. The two terms are related, but they are kind of like opposites, so make sure you don't get them confused.

Definition of Carrying Capacity

The number of organisms that an environment can support (its maximum population) is called its carrying capacity. The carrying capacity is determined by limiting factors.

Logarithmic growth is when a population experiences rapid growth at smaller sizes. But, as the population density increases, the rate of growth (birth rate) slows down, eventually not growing anymore as it hits its capacity.

In natural settings, populations often exceed the carrying capacity. There are too many individuals for the environment to support. The population then dips as the death rate increases, falling below the capacity. The population will continue to bounce back and forth above and below that limit.

This phenomenon is due to the fact that there is a delay in reproduction. Organisms will continue having offspring after they reach that population limit. This new round of offspring will send them over the capacity and the population will then crash.

Is there a Human Carrying Capacity?

So, is there a human carrying capacity? Of course there is. Humans are a species, and we need stuff to live. There isn't an infinite water supply, amount of food, or other natural resources available, which means the Earth can't support an infinite number of humans. Take food production for example. Human population growth means more food is needed, but more food doesn't just appear magically. Some ways scientists try to address this problem are by finding ways to reduce food waste or by genetically engineering crops.

(Video) Population Ecology: The Texas Mosquito Mystery

by CrashCourse

There is a point where an ecosystem cannot support any more members of a population. In this video, Crash Course discusses this phenomenon, which is called carrying capacity.

A population consists of members of one species which live in a given area. The size of a population changes constantly due to births, deaths, and migration. Additionally, for a given area, a population can be distributed in many different ways. It can be widely dispersed or the members can live very closely together.

Carrying Capacity and Limiting Factors

These are some of the factors that determine the size and growth potential of a population. Population growth depends on carrying capacity, and the capacity is restricted by limiting factors. These are the things that are, in fact, limited in the natural world. For example, food, water, and shelter are limited in nature but are also necessary for survival. There are only enough natural resources to consistently support so many individuals. If the population increases past the capacity, many members will quickly die out due to a lack of food or other resources.

$$\color{#8925AE}{\text{Vocabulary Review:}}$$

$\color{#8925AE}{\text{Carrying Capacity}}$ : The maximum number of organisms from a specific population that an ecosystem can support

$\color{#8925AE}{\text{Logistic Growth}}$ : After an exponential increase in population size, the growth rate slows down or stops