How many animals can an ecosystem support? This is the question scientists ask themselves when they are trying to determine the carrying capacity of an area. Learn how scientists evaluate factors that limit carrying capacity.

## Carrying Capacity

Let’s say your soccer team goes to a pizza buffet after playing a soccer game. The pizza buffet has five different pizzas with all your favorite toppings. This is plenty of pizza to support you and your teammates. But what happens if the opposing team shows up at the same pizza buffet? Now, there are only five pizzas for two soccer teams. If the owner of the pizza place can’t keep up with the demand for food, some of the players will go hungry.

This is kind of what happens when we look at a concept in science known as carrying capacity. Carrying capacity is the maximum number of living organisms that an environment can support. From our example, we see that the carrying capacity for the pizza buffet was one soccer team. When this amount of customers was exceeded, the pizza place could not get the pizzas made and out fast enough to feed everyone, so food became a limiting factor, meaning something that restricts the number of organisms that can be supported.

In this lesson, we will look at how carrying capacity within animal populations is affected by availability of food and other limiting factors.

## Ecosystems

Scientists study carrying capacity in order to determine if an ecosystem is sustainable. You remember that an ecosystem is the community of animals, plants, and other organisms that live in the same area. There are different types of ecosystems, from forests to oceans to deserts. Ecosystems provide the resources a species of animals needs in order to live, feed, and reproduce. However, an ecosystem can only support a certain number of animals before problems start to arise.

## Limiting Factors

So how do scientists determine how many animals can live and thrive in an area? To do this, they evaluate the limiting factors. In our pizza parlor, we saw that the limiting factor was food; five pizzas was not enough food to feed two hungry soccer teams. In a natural environment, availability of food is also a limiting factor.

For example, let’s say a small forest can support two bears very easily because there’s plenty of vegetation and berries for the bears to eat. But if two more bears move into the forest, there will be a problem. The four bears will eat all of the available food. When the food is gone, the area can no longer sustain a bear population. In this case, we would say the maximum carrying capacity of the small forest is two bears.

Food is not the only limiting factor. The availability of water can also limit the carrying capacity of an environment. Why do we not see bears living in the middle of a desert? Well, one thing that’s missing is an adequate water supply. All animals rely on water to survive. If there’s little water available, that ecosystem cannot sustain a big animal population.

One more limiting factor to consider is availability of shelter. While a desert provides plenty of space for hundreds of bears, the lack of shelter from the scorching heat and harsh winds is a limiting factor that makes a desert ecosystem unfriendly to bears.

So what types of animal species call the desert home? Well, scorpions are one example of a species that finds the desert a lovely place to raise a family. They thrive by eating insects, spiders, ants, and other creepy crawlies. They don’t need to drink much water because they get enough hydration from eating their prey. And, as for shelter, scorpions are able to burrow under the sand, which lets them avoid the harsh sun and high desert temperatures. This sandy shelter also provides protection from anything that wants to eat them.

## Lesson Summary

Let’s review.

Carrying capacity is the maximum number of living organisms that an environment can support. Scientists study carrying capacity in order to determine the sustainability of an ecosystem, which is the community of animals, plants, and other organisms that live in the same area.

The maximum carrying capacity can be reduced if there is a limiting factor, which is something that restricts the number of organisms that can be supported. In this lesson, we learned that the availability of food, water, and shelter are examples of limiting factors.

## Learning Outcomes

By the time you have finished this lesson, you might demonstrate the ability to:

• Describe an environment’s carrying capacity
• Understand why scientists study an ecosystem’s carrying capacity
• Recognize some limiting factors in an environment