investigating populations

Slide 1

Measuring AbundanceRadom sampling and transects with quadrats gives us a measure of abundance.

Abundance is the number of individuals of a species within a given space.

It can be measured in several different ways. Measuring Abundance: FrequencyIs the likelihood of a particular species occurring in a quadrat. This method is useful when a species is hard to count e.g. grass. Advantage: gives a quick idea of species present and their general distribution.Disadvantage: does not provide information on density and a detailed distribution.

Measuring Abundance: Percentage CoverIs an estimate of the area within a quadrat that a particular species covers.Useful when a species is abundant or difficult to count.Advantages: data can be collect rapidly. Individuals need not be counted.Disadvantage: Less useful where organisms occur in overlapping layers e.g. plants. When measuring abundance you must remember to:Use a large sample size.

Calculate a mean

Why?