A quadrat is a sqaure frame used for studying ecosystems.
- It is used to study the abundance and distribution of different plant species
- Some plants are difficult to count as individuals so percentage cover is used instead
Some precautions must be taken:
- Randomly position the quadrats across the habitat, using random numbers to plot coordinates.
- You need your sample size to be large enough. Ecologists create a cumulative frequency table. When the graph levels off, you know that your sample size is large enough.
Population size of a species
Population size of a species =
Mean number of individuals of the species in each quadrat
Fraction of the total habitat area covered by a quadrat
- These help you to look more systematically for changes in vegetation in a habitat.
- A transect is a line taken across the habitat.
- This line is usually created using a tape measure.
- Samples are taken at random intervals.
There are two approaches to taking a transect:
- Line transect - at regular intervals, take note of the species touching the tape measure.
- Belt transect - at regular intervals, place a quadrat next to the line or move the quadrat along the line to get a more accurate representation of the habitat.