Density and Dispersion patterns
Population density
Population density is the number of individuals of a species per area or volume. Because it is almost impossible to count every single individual living in an area, ecologists use sampling techniques to estimate the density of a population. Ecologists noticed that the bigger the number and size of the samples, the more accurate the results will be. Some population densities are estimated using indirect indicators, for example birds nest or rodent burrows. Dispersion patterns refers to how individuals are spaced out within an area.
Clumped dispersion patternThe most common dispersion is clumped. In clumped dispersion patterns, individuals are grouped in patches, a result of unequal distribution of resources. For example, sea stars are often clumped where food is abundant.
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Uniform dispersion patternUniform dispersion patterns are often evenly spaced out, a result of interactions between the individuals in a population. For example, some plants secrete chemicals that can affect the growth and germination of other plants that compete for the same resources.
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Random dispersion patternIn random dispersion patterns. individuals are spaced without a pattern. Some plants, such as dandelions, that grow from windblown seeds are often randomly dispersed. However, habitat conditions and social interactions make random dispersion rare.
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