"Populations are groups of individual organisms of the same kind that live in a specific area together"

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"In a given forest ecosystem there might be a population of deer, a population of birch trees, and a population of mosses. In any ecosystem there is a large variety of populations. All populations together make up the community."

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population density is the term used by scientists to describe

"the number of individual organisms of a particular species in a particular area of an ecosystem"

To measure the population density of a community, scientists take samples of a population. A sample is a part that represents the entire population. Scientists use these samples to estimate the size of a population in an area. To get a sample, scientists count the number of organisms in a small area. They than monitor changes in this number.

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Limits on population density

Density increases if a population is surviving well in an ecosystem. If a population has all the resources it needs for survival, it's density will increase. However these resources are not always available.

 

A populations ability to grow is limited by food and water supply, disease, shelter, and other factors in the environment. This ability to grow in a given time is a population's growth rate.

 

Many factors limit how much a population can grown in any given ecosystem, such as food or water. Some factors are common in all populations. Some factors only affect certain populations, such as disease. An ecosystem and it's factors will not support population growth forever. At some point, it's population reaches it's carrying capacity for it's ecosystem. The carrying capacity is the largest density an ecosystem can support for a particular population.

 

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