--- title: "Measuring Diversity: Richness, Evenness and Turnover Between Sites" description: "Counting species is not enough, because two communities with the same number of species can differ in how evenly individuals are spread. Indices combine richness and evenness, and a separate measure c" canonical: https://lightmysky.com/learn/science/measuring-diversity-richness-evenness-and-turnover-between-sites-mt_d_iIiIArWZ source: https://lightmysky.com/learn/science/measuring-diversity-richness-evenness-and-turnover-between-sites-mt_d_iIiIArWZ.md retrieved: 2026-09-12 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Measuring Diversity: Richness, Evenness and Turnover Between Sites Counting species is not enough, because two communities with the same number of species can differ in how evenly individuals are spread. Indices combine richness and evenness, and a separate measure compares which species differ between sites. Subject: Science · Area: Ecology & Conservation · Ages 21 to 22 Page: https://lightmysky.com/learn/science/measuring-diversity-richness-evenness-and-turnover-between-sites-mt_d_iIiIArWZ ## Ready when they can - Calculates a diversity index from abundance data and explains what evenness contributed. - Compares two communities with equal richness and different evenness. - Distinguishes diversity within a site from turnover between sites. ## Lesson: Beyond counting species Species diversity has two moving parts. Richness is the simple count of species present. Evenness describes how individuals are shared among them, from perfectly balanced to ruled by one. A forest with 10 equally common trees is more diverse than one with 10 species where a single tree covers 90 percent of the ground. **Example.** Picture two meadows, each with 5 species and 100 plants. The first holds 20 of each, while the second holds 92 of one and 2 of each other. Richness ties at 5, but the even meadow is more diverse because dominance by one species drags diversity down. Balanced communities also keep backup species ready when conditions shift. To compare two communities, count individuals per species at each site, then line up the lists. Note richness, note evenness, and note which species are shared and which are unique. Diversity within one site is alpha diversity, while turnover in species between sites is beta diversity: high turnover means each site guards species found nowhere else. **Tip.** When richness ties, let evenness decide. When both tie, let the unique species decide: the site holding more one-place-only species carries the higher conservation value. **Recap.** Richness counts species, evenness shares individuals, and turnover compares sites. ## Practice 8 questions on this page, each with its working shown. ## Needs first - [Sampling Ecosystems with Quadrats and Transects](https://lightmysky.com/learn/science/sampling-ecosystems-with-quadrats-and-transects-mt_jI8rAOYdmb) ## Opens up - [The Host Microbiome: Composition, Causation and Intervention](https://lightmysky.com/learn/science/the-host-microbiome-composition-causation-and-intervention-mt_-F8lNccQCU) - [Biogeography: Why a Species Is Here and Not There](https://lightmysky.com/learn/science/biogeography-why-a-species-is-here-and-not-there-mt_sRi0FPcK8r)