Species Richness Calculator
Calculate species richness, diversity indices, and biodiversity metrics for ecological surveys
Species Data
| # | Species | Abundance | Action |
|---|
Species Richness (S)
Total number of species
Total Abundance (N)
Total individuals counted
Shannon-Wiener (H')
Diversity index (nats)
Simpson's Index (D)
Probability two individuals are different species
Pielou's Evenness (J')
0 = uneven, 1 = perfectly even
Margalef's Index (DMg)
Richness relative to sample size
Diversity Assessment
Abundance Distribution
Calculation Details
| Index | Formula | Value |
|---|
Understanding Species Richness and Biodiversity Indices
Species richness is the simplest measure of biodiversity - it is simply the count of different species present in a given area or sample. However, richness alone does not capture the full picture of biodiversity. Ecologists use several diversity indices that also account for the relative abundance (evenness) of each species. A community with 10 species where each has 100 individuals is considered more diverse than one with 10 species where one species has 910 individuals and the rest have 10 each.
Key Diversity Indices
- Species Richness (S): Total number of different species in the sample. Simple but sensitive to sampling effort
- Shannon-Wiener Index (H'): Accounts for both richness and evenness. Typically ranges from 1.5 to 3.5, rarely exceeds 4.5. Higher values indicate greater diversity
- Simpson's Diversity Index (1-D): The probability that two randomly selected individuals belong to different species. Ranges from 0 to 1, with higher values indicating greater diversity
- Pielou's Evenness (J'): Measures how evenly individuals are distributed among species. Ranges from 0 (one species dominates) to 1 (all species equally abundant)
- Margalef's Richness Index (DMg): Adjusts species richness for sample size using the formula (S-1)/ln(N). Values below 2 indicate low diversity, above 5 indicates high diversity
- Berger-Parker Dominance (d): The proportional abundance of the most common species. Higher values indicate greater dominance by a single species
When to Use Each Index
Shannon-Wiener (H')
- • Most widely used diversity index
- • Sensitive to rare species
- • Good for comparing communities
- • Assumes random sampling of all species
Simpson's Index (1-D)
- • Weighted toward common species
- • Less sensitive to sample size
- • Intuitive probability interpretation
- • Good for dominance-focused analysis
Pielou's Evenness (J')
- • Complements richness measures
- • Identifies uneven distributions
- • Useful in conservation assessments
- • Detects community disturbance
Margalef's Index (DMg)
- • Corrects richness for sample size
- • Easy to calculate and interpret
- • Good for quick field assessments
- • Useful for water quality monitoring
Example: Comparing Two Communities
Both communities below have 5 species and 100 total individuals, but very different diversity:
Community A (Even)
Species abundances: 20, 20, 20, 20, 20
- • H' = 1.609 (high)
- • Simpson's 1-D = 0.800
- • Evenness J' = 1.000
Community B (Uneven)
Species abundances: 92, 2, 2, 2, 2
- • H' = 0.384 (low)
- • Simpson's 1-D = 0.153
- • Evenness J' = 0.239
References
The diversity indices and formulas used in this calculator are based on foundational ecology literature and widely accepted methodology:
- Magurran, A.E. (2004). Measuring Biological Diversity. Blackwell Publishing
- Shannon, C.E. & Weaver, W. (1949). The Mathematical Theory of Communication. University of Illinois Press
- Simpson, E.H. (1949). Measurement of Diversity. Nature, 163, 688
- Pielou, E.C. (1966). The Measurement of Diversity in Different Types of Biological Collections. Journal of Theoretical Biology, 13, 131-144
- Convention on Biological Diversity - Global Biodiversity Outlook 5 (GBO-5)
- IUCN Red List of Threatened Species
Note: This calculator provides standard ecological diversity indices for educational and research purposes. Results depend on sampling methodology, effort, and completeness. For rigorous ecological studies, consider rarefaction analysis, species accumulation curves, and appropriate statistical tests. The Shannon-Wiener index uses natural logarithm (ln) following the most common convention in ecology.
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