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Biodiversity 6 min read November 24, 2025

Measuring Biodiversity: The Shannon Diversity Index in Plain English

How ecologists quantify 'variety' in an ecosystem, and why a higher Shannon score usually means a healthier system.

The formula

H' = −Σ (pᵢ × ln pᵢ), where pᵢ is the proportion of species i. Higher = more diverse. Most natural ecosystems score 1.5–3.5.

Frequently asked questions

What's a good Shannon Index?
Above 3.0 is considered high diversity; below 1.5 indicates a system dominated by few species.
biodiversity ecology conservation