Here is a graph of logistic growth with the point at which the resources for the population are no longer abundant enough to support exponential growth labeled:
The Graph
Carrying Capacity
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Population
The carrying capacity is the limit a place can handle for its population. When there are not enough resources to support more growth, the population growth slows down until it reaches the maximum level the environment can sustain.
As more people exist, they use up more resources in their surroundings. This strain on resources like food and water slows population growth. Ultimately, when resources can only support the existing population, growth halts.
The carrying capacity of an environment can be affected by a number of factors, such as the availability of resources, the rate of resource renewal, and the efficiency with which resources are used. As these factors change, so too can the carrying capacity of an environment.