Ecological Techniques

Edexcel A-level BiologyThe Nature of EcosystemsLesson 30 of 39

Ecologists cannot count every organism in a habitat, so they take samples and use them to estimate the whole population. A good sample must be representative of the habitat.

The choice of method depends on the question:
- Random sampling is used to estimate abundance or compare two areas. Lay out two tape measures at right angles to form a grid, then use a random number generator to pick coordinates. This removes bias in choosing where to sample.
- Systematic sampling is used where conditions change across an area, for example from a hedge into a field. Samples are taken at regular intervals along a line.

More in The Nature of Ecosystems

• Intraspecific Competition
• Interspecific Competition
• Species Abundance
• Species Distribution
• Quadrats
• ACFOR Scale
• Point Quadrats
• Permanent Quadrats

All 39 lessons in The Nature of Ecosystems · All Edexcel A-level Biology topics