BRAINCAKESystematic Sampling along Transects
When an abiotic factor changes gradually across an area, random sampling may miss the pattern. Examples include the change from low tide to high tide on a rocky shore, from the sea to inland on a sand dune, or from the shade of a wood into an open field. Here, ecologists use systematic sampling along a transect: samples are taken at regular intervals along a line.
Stretch a tape measure across the area in the direction of the change. Then use one of two methods.
Line transect
Record every species that touches the line at regular intervals, for example every metre. It is quick but gives no measure of abundance.
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More in Populations in Ecosystems
- Interspecific Competition
- Predator-Prey Relationships
- Estimating Population Size with Quadrats
- Random Sampling with Quadrats
- Mark-Release-Recapture
- Assumptions of Mark-Release-Recapture
- Succession
- Primary Succession
All 20 lessons in Populations in Ecosystems · All AQA A-level Biology topics