Hi Jessy:
Species richness S is the simplest measure of biodiversity and is simply a count of the number of different species in a given area. This measure is strongly dependent on sampling size and effort.
The Margalef diversity index can easily be calculated in a spreadsheet:
d = (S - 1) / ln N
Where S is the number of species, and N is the total number of individuals in the sample
However you must be cautious when using Margalef index, as the results are very different if densities are used instead of total numbers. There is a good example by Reserach Gate member Sofia Gamito (2010)
Gamito, S. 2010. Caution is needed when applying Margalef diversity index. Ecological Indicators10: 550–551.
https://sapientia.ualg.pt/bitstream/10400.1/2501/1/Gamito%202010%20Caution%20Margalef%20index.pdf
Regards,
Luis Miguel
Hi Jessy
A good index of diverisity should follow the replication principle and also independent of the sample size; thus I recommend to use the effective number of species (hill numbers) and rarefy the species richness.
also see:
Chao A, Chiu CH, & Jost L (2010) Phylogenetic diversity measures based on Hill numbers. Proceedings of the Royal Society B-Biological Sciences 365: 3599–3609.
http://www.wcsmalaysia.org/analysis/Biod_indices.htm
Best wishes!
Wumei
Dear Jessy,
On this index I can add that its pluses is easy calculation and high discriminant capacity. But it is strongly influenced by sample size and its use is not very common.
On biodiversity indices see:
Magurran A.E. (1988) Ecological diversity and its measurement. ISBN 0-7099-3539-0.
Best wishes,
Elena
The Margalef diversity index (Margalef, 1958) expressed as 'd' can be calculated in a spreadsheet by using the formula
d = (S − /)1 ln N
Where S is the number of species, and N is the total number of individuals in the sample. Software packages calculates the Margalef diversity if a density data set is introduced instead of absolute numbers.
As mentioned by Canstantino, a brief but crispy information on Margalef Index by Gamito (2010) in Ecological Indicators 10: 550-551 will be useful in better understanding of the index.
During his later years, Ramón Margalef was not happy at all with ecologists uncritically using his "index" as a measurement of species richness, and repeatedly cautioned against its systematic usage as, in particular, some sort of "indicator" of the ecosystem's "health". Although I never hear him voice it, it has been posited that one reason for its widespread (and often wrong) use was its extremely simple formulation.
Margalef insisted in that he merely proposed the index as a just a concept behind the species-area curve. He proposed it when describing the special case where all species would be uniformly distributed, and the linear relationship between the number of species and the logarithm of the number of individuals would represent a geometric distribution when the species' abundances were ordered (not difficult to visualize using a Whittaker plot).
And. as Elena, Xu and Luis said above, it is unbounded and strongly dependent on sample size--precisely because it is, in a way, a representation of a family of species-area curves.
Margalef, 1980: Ecología. Omega, Barcelona.
Arturo makes some excellent points! I discuss the index at length in my 2013 publication (available here). In re to Arturo- often a log normal species distribution results in geometric distributions of ecologically relevant communities. Thus by extension, I also believe the index applies to log normal species distributions.
An excellent Power point presentation of James A. Danoff-Burg will be useful for you to compare Margalef and other indices
Gracias por tan buenos aportes. No soy bióloga pero me estoy iniciando en el estudio de paisaje. Me interesa determinar la riqueza y abundancia de los árboles que varias zonas determinadas. Creo que esto me ayudará.
This is the simplest measurement as touching biodiversity, and must be used with caution.
Some scientists are using Margalef Index formula D=(S-1)/Log(N), but they are calculating with ln value rather log value. I think we should use the formula D=(S-1)/Ln(N), if Ln value is used. Otherwise the information will be erroneous. Now my question is what is the range of Richness Index or Margalef Index value?
I think the range of richness index is "observed species" to "species distribution".
Shannon's entropy and evenness also reflect richness and distribution.
High level of Shannon's entropy means even distribution. If A species is dominant, the A got dominance-richness and reduces the distribution of species.
The richness focus on the amount, evenness focus on distribution but the range is same I think.
https://www.researchgate.net/publication/318760929_My_Village_Biodiversity_Documentation_of_Western_Ghats_Biodiversity_through_Network_of_Students_and_Teachers
https://www.researchgate.net/publication/331076568_Global_Warming_Mitigation_Through_Carbon_Sequestrations_in_the_Central_Western_Ghats/stats
https://www.researchgate.net/publication/323180165_Salient_Ecological_Sensitive_Regions_of_Central_Western_Ghats_India
https://www.researchgate.net/publication/332331409_Sustainable_Management_of_Bannerghatta_National_Park_India_with_the_Insights_in_Land_Cover_Dynamics
https://www.researchgate.net/publication/301609558_Geospatial_analysis_of_forest_fragmentation_in_Uttara_Kannada_District_India
Why do some people use Log while some use Ln to calculate the Margalef's index? Which one is correct?
Article Measuring the ecological preference for growth of150 of the ...
https://www.cell.com/heliyon/fulltext/S2405-8440(19)35821-9
https://www.cell.com/heliyon/fulltext/S2405-8440(18)38688-2
¡Hi Jessy!
As much as the answers many people give you, I want to know what about your question.
If you are looking for an index based on species richness weighted by the number of individuals in your sample, I suggest you use Hill's numbers (q = 0).
Best,
Sergio Lopez
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