Diversity Indices
Calculate Shannon, Simpson, and other diversity metrics.
Overview
Diversity indices quantify the variety and distribution of species in a community. FieldEco calculates several standard ecological diversity measures automatically.
Shannon Diversity Index (H’)
The most commonly used diversity index, accounting for both richness and evenness.
Formula
H' = -Σ(pi × ln(pi))
Where pi = proportion of individuals of species i
Interpretation
| H’ Value | Interpretation |
|---|---|
| 0 | Single species |
| 1.0-1.5 | Low diversity |
| 1.5-2.5 | Moderate diversity |
| 2.5-3.5 | High diversity |
| >3.5 | Very high diversity |
Notes
- Typical range: 0-4 (occasionally higher)
- Sensitive to rare species
- Log base affects values (FieldEco uses natural log)
Simpson’s Index
Measures the probability that two randomly selected individuals belong to different species.
Variants
Simpson’s Index (D)
D = Σ(pi²)
Simpson’s Diversity (1-D)
1-D = 1 - Σ(pi²)
Simpson’s Reciprocal (1/D)
1/D = 1 / Σ(pi²)
Interpretation
| 1-D Value | Interpretation |
|---|---|
| 0 | No diversity (single species) |
| 0.5 | Moderate diversity |
| 0.8-0.9 | High diversity |
| ~1.0 | Very high diversity |
Notes
- Range: 0 to 1 (for 1-D)
- Less sensitive to rare species than Shannon
- Emphasizes dominant species
Pielou’s Evenness (J’)
Measures how evenly individuals are distributed among species.
Formula
J' = H' / ln(S)
Where S = total number of species
Interpretation
| J’ Value | Interpretation |
|---|---|
| 0 | Highly uneven (one species dominates) |
| 0.5 | Moderately even |
| 0.8-1.0 | Very even distribution |
| 1.0 | Perfect evenness |
Hill Numbers
A unified framework for diversity indices.
Definition
qD = (Σ pi^q)^(1/(1-q))
Common Hill Numbers
| Order (q) | Name | Emphasis |
|---|---|---|
| 0D | Species richness | All species equal |
| 1D | Shannon diversity (exp H’) | Typical species |
| 2D | Simpson diversity (1/D) | Dominant species |
Advantages
- Comparable across studies
- Clear interpretation (effective species)
- Mathematically unified
Using Analysis in FieldEco
Running Analysis
- Open your completed survey
- Tap Analysis button
- Select Diversity Indices
- View results
Data Requirements
- Minimum 2 species
- Count data for each species
- Complete survey data
Results Display
FieldEco shows:
- All calculated indices
- Interpretation guides
- Comparison with benchmarks
- Export options
Best Practices
Sampling Considerations
- Use consistent methodology
- Standardize sampling effort
- Account for detectability
- Note any biases
Interpretation
- Compare like with like
- Consider sample size
- Report confidence intervals
- Use multiple indices
Reporting
Include:
- Index name and formula
- Sample size and effort
- Habitat/context
- Standard errors if available
Related Documentation
- Species Richness - Richness estimation
- Checklist Survey - Data collection
- Quadrat Survey - Plot-based sampling