Read Biodiversity as Richness and Evenness
A focused NSEB read for comparing biological communities without confusing the number of species with how individuals are distributed among them.
Biodiversity Measurement is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Count richness separately
Species richness is the number of species present. In the bird table, plots 2 and 3 both record nine species, so their richness matches. Richness alone does not tell whether one or two species dominate the community.
Then inspect evenness
Evenness is higher when individuals are spread more similarly across species. Plot 2 is dominated by sparrows and crows, whereas plot 3 has lower dominance and a more balanced spread. Compare relative abundance before claiming two plots have the same biodiversity pattern.
Make the observation reliable
Equal effort and comparable conditions make counts fairer. Repeated observations across a biologically relevant period, including nesting time for breeding birds, reduce the chance that a brief count misrepresents the community.
OlympIQ exam lens
- ✓Richness = number of species.
- ✓Evenness = balance of individuals across species.
- ✓Hold survey effort and conditions comparable.
- ✓Repeat observations to improve reliability.
Two plots can contain the same number of species while differing greatly in dominance and evenness.
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