BRAINCAKESampling Distribution and Abundance
It is almost never possible to count every organism in an area, so ecologists take samples and use them to estimate the whole population. Distribution is where organisms are found in a habitat; abundance is how many individuals of a species are present.
Random sampling avoids bias: the area is divided into a grid and coordinates are chosen with a random number generator. Non-random sampling includes opportunistic (choosing convenient sites), stratified (sampling each distinct zone in proportion to its size) and systematic sampling (at regular intervals, for example along a transect, useful where conditions change across an area).
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More in Ecosystems
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- Secondary Succession
- Deflected Succession
- Quadrats and Transects
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All 21 lessons in Ecosystems · All OCR A-level Biology topics