Comparing biodiversity with quadrats
Place 1 m quadrats in a school field, at a forest edge and on a trampled path, count the plant species, and find how many quadrats are enough.
Core concept
Biodiversity can be compared by sampling with quadrats; more samples find more species until the count levels off
Topic: Ecosystems
Biodiversity is the variety of living things in a place. We cannot count every plant in a habitat: The natural home of a plant or animal, like a pond or a forest. All key words, so ecologists take samples. A quadrat is a square frame, here 1 m by 1 m, placed at random places in the habitat; you record every species inside it. The first few quadrats find many new species, but as you add more, fewer new species turn up, until the count levels off. That tells you that you have taken enough samples. Comparing the levelled-off counts shows which habitat has more species.
What you will learn
- Use quadrats to sample plant species.
- Decide how many quadrats are enough from a species-quadrat graph.
- Compare the biodiversity of different habitats and explain the differences.
Before you start
- Know what a species and a habitat are.
Materials
- Plant identification chart, notebook
Equipment
- 1 m quadrat frame, tape measure, random number table
Procedure
- In the school field, place quadrats one at a time and record the total number of species found, up to 10 quadrats.
- Repeat at the forest edge, up to 10 quadrats.
- Repeat on a trampled path, with 10 quadrats.
How this simulation is simplified
- The species found approaches the habitat's total along a smooth curve: field 6 species, forest edge 14, trampled path 3.