(noun) A measure of the amount of matter contained by a given volume.

Abundant: a species is said to be abundant when it is locally numerous or occurs in high densities. Community: an assemblage of two or more interacting populations of different species occupying the same geographical area at a given time.

1. density that can be changed by altering the number of individuals per given unit of space. Social density is a major determinant of crowding, and there is evidence that it has a more powerful effect on human response than spatial density. 2.

The formula for calculating population density is: Population density = Population / Land area in square miles (or square kilometers)

Individuals of a population can be distributed in one of three basic patterns: they can be more or less equally spaced apart (uniform dispersion), dispersed randomly with no predictable pattern (random dispersion), or clustered in groups (clumped dispersion).

There are two types of dispersion systems, Molecular Dispersions and Coarse Dispersions.

Dispersion is defined as the breaking up or scattering of something. An example of a dispersion is throwing little pieces of paper all over a floor. An example of a dispersion is the colored rays of light coming from a prism which has been hung in a sunny window.

Density-dependent factor, also called regulating factor, in ecology, any force that affects the size of a population of living things in response to the density of the population (the number of individuals per unit area).

Density-dependent factors include competition, predation, parasitism and disease.

Density-independent factors are the ones that are not dependent on the population density. They affect the species regardless of how dense the population is. These include natural disasters, like floods, drought, tornadoes, etc., climate, and even human activities.

Density-dependent selection occurs when the fitnesses of genotypes within a population respond differently to changes in total population size or density. Density-regulation of a population in a constant environment implies that fitnesses decrease as population size increases.

Carrying capacity can be defined as a species’ average population size in a particular habitat. The species population size is limited by environmental factors like adequate food, shelter, water, and mates. If these needs are not met, the population will decrease until the resource rebounds.

Earth’s capacity Many scientists think Earth has a maximum carrying capacity of 9 billion to 10 billion people.

In a population at its carrying capacity, there are as many organisms of that species as the habitat can support. If resources are being used faster than they are being replenished, then the species has exceeded its carrying capacity. If this occurs, the population will then decrease in size.

As competition increases and resources become increasingly scarce, populations reach the carrying capacity (K) of their environment, causing their growth rate to slow nearly to zero. This produces an S-shaped curve of population growth known as the logistic curve (right).

Carrying capacity is most often presented in ecology textbooks as the constant K in the logistic population growth equation, derived and named by Pierre Verhulst in 1838, and rediscovered and published independently by Raymond Pearl and Lowell Reed in 1920:Nt=K1+ea−rtintegral formdNdt=rNK−NKdifferential formwhere N is …

carrying capacity into six categories: physical, economic, perceptual, social, ecological and political.