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Richness S with Margalef/Menhinick indices, Shannon H′, Pielou evenness J, and Berger–Parker dominance from a named or plain species list.
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Tool usage guide
Paste a named species list or plain abundance counts to compute richness S, sample-size-corrected Margalef and Menhinick indices, Shannon H′, Pielou evenness J = H′/H′max, and Berger–Parker dominance of the most abundant taxon.
Background
A 100-stem quadrat recorded five tree species with fairly similar abundances.
Problem
Need S, sample-size-corrected richness, Shannon H′, Pielou J, and which species dominates.
How to use
Paste the named list into Species counts.
Oak: 34
Maple: 28
Beech: 22
Pine: 11
Birch: 5Outcome
S = 5, N = 100, Margalef d = 0.8686, Menhinick d = 0.5, H′ = 1.4489, H′max = 1.6094, J = 0.9003, Berger–Parker = 0.34 (Oak). Highly even community.
Background
Four taxa were tallied as 80, 10, 6 and 4 individuals with no names recorded.
Problem
Determine whether low diversity is due to few species or to one taxon monopolizing the sample.
How to use
Paste the four numbers, one per line (or comma-separated).
Named lines such as Oak: 34 (or with ; = , | or tab) or plain numbers on separate lines or separated by commas or spaces. Duplicate names are merged by summing counts.
J = H′ / ln S (i.e., H′ / H′max). Values near 1 indicate nearly equal abundances; lower values indicate dominance.
Both correct richness for sample size: Margalef d = (S − 1) / ln N and Menhinick d = S / √N. Higher values mean more species relative to the number of individuals counted.
Yes. Plain numbers are treated as successive species (Species 1, Species 2, …) so dominance can still be reported.
The proportion of all individuals that belong to the single most abundant species. High values (e.g., 0.8) indicate a strongly dominated community.
80
10
6
4Outcome
S = 4, N = 100, Margalef d = 0.6514, Menhinick d = 0.4, H′ = 0.7063, H′max = 1.3863, J = 0.5095, Berger–Parker = 0.8 (Species 1). Highly uneven; one species holds 80 % of individuals.