As population size increases, so does the demand for resources.

Carrying capacity helps define the appropriate size of a population based on its environment. The availability of resources has a direct effect on how quickly and how large a population can grow.

## Carrying Capacity of Population

As a new population grows in an environment, it will experience what is called **exponential growth**.

This means that the population grows very quickly over a short amount of time. On a graph, exponential growth looks like the letter ‘J.’ However, since resources are limited, no environment can support this type of growth for very long. The growth of the population begins to level out and takes the shape of an ‘S.’ This type of population growth is called **logistic growth**.

## Lesson Summary

**Exponential growth** is when a population grows very quickly over a short amount of time.

When the growth of the population begins to level out, it is called **logistic growth**. As population growth becomes more restricted, and the size of the population reaches stability, that population reaches its **carrying capacity**. A cyclical fluctuation in population growth is called the **stable limit cycle**. **Damped oscillations** are fluctuations of population size above and below the stable limit cycle that lessen with time, and when a population **crashes**, the resources in the environment become so depleted that the population size becomes very small very quickly.

Although *K* is unique to each population, the concept is universal: resources in nature are limited. Natural populations rarely become entirely stable and tend to fluctuate around *K* in regular cycles or chaotic patterns. Although a population may experience rapid growth at first, it will eventually level off at a point that is well suited for both it and the environment.