3.1.7—Species diversity components
- Syllabus
- First assessment 2026
- Objective
- 3.1.7
- Level
- HL
Combine Species Richness with Evenness
Richness counts species; evenness asks how evenly individuals are distributed among them.
Species diversity uses both. Equal richness can hide dominance, so inspect abundance distribution before ranking communities.
Site A has 25 individuals of each of four species; Site B has 97 of one and one of each other. A is more even and usually more diverse.
Counts or relative abundance; richness alone cannot reveal dominance.
More species does not automatically mean a more even or functionally diverse community.