Dear Deepthi,

it interpreted more diversity of the communities.

High values of H would be representative of more diverse communities. A community with only one species would have an H value of 0 because Pi would equal 1 and be multiplied by ln Pi which would equal zero.

If the species are evenly distributed then the H value would be high. So the H value allows us to know not only the number of species but how the abundance of the species is distributed among all the species in the community.

you can hardly interpret diversity values without comparing them with values for the same/ a similar organism groups and ecosystem. The Shannon diversity index is frequently used, so you ought to be successful finding data for comparison. Even then I doubt, whether the formula high diversity = good, low diversity = bad is always true.

If you really want to understand what is going on with diversity, read: Tuomisto 2010 in Oecologia, 2010a,b in Ecography, and 2012 in Oikos

When comparing with other site/time, keep in mind that using "numbers of equivalent" will give you more intuitive results. For Shannon's index as example, its equivalent number is exp (H). Also see Lou Jost, Ecology 88, 2427 - 2439.

Hi,

according to my knowledge, the number of shannon-weiner index depend on the total namber of Species that you have in your projects and some another parameters like disturbance , rich ness and ...

So it better you par attention to all parameters but if every thing is ok, you will have a good situation for rich ness and have good quality in biodiversity

good luck

Hi,

This value can be interpreted in terms of the fact that the site is serving as a good and undisturbed habitat for the corals. And if it is a site-wise comparison study, its always better to thoroughly look for your hypothesis as what factors influence these group of organisms and just to make sure about the results.

Good luck!!

Please contact Mr Ashutosh Kumar of IITR, India for this. He is doing research work related to this aspect. His email ID is [email protected]. Good luck

I think the number alone is meaningless, unless you compare it to the diversity value for another community. You should also clarify whether you use bits or nats.

The Shannon-Weiner diversity represent the proportion of species abundance in the population. Its being at maximum when all species occur in similar number of individuals and the lowest when the sample contain one species. From my experience there is no limit to compare the diversity value with as for evenness, which resricted between 0-1. For Example, if the sample contain 4 species each represented by 5o individuals the, diversity H equal 1.3863, and if the sample contain 5 species (one more) and each represented by similar number of individuals (50), the diversity equal 1.6094. So it is better to compare the result with another location or period to find out the difference. But usually the diversity value over 3 referr to good level.

Rgds

The Shannon-Weiner diversity index as a single value is of less statistical significance. For a community either season wise comparisons or for a season location wise comparisons give a better idea. The example by T Al Dawood is self explanatory. Tuomisto's publications are also good but you will understand them better if you have sound maths background.

You can find your answer from one of my article.

http://www.innspub.net/wp-content/uploads/file/JBES-V2No12-p24-40.pdf

you see: Biodiversity of plant species in Tehsil Takht-e-Nasrati, Pakistan by Musharaf Khan, Farrukh Hussain and Shahana Musharaf. International Journal of Biodiversity and Conservation Vol. 5(1), pp. 39-46, January 2013.

The S-W Diversity Index is a relative measure and does not really mean much by itself; you really need to compare it with an index value from another community. Whichever community has a higher index value is the more diverse. You then need to go back and look at your data to see if the difference is due to greater richness, evenness, or both.

Instead of the S-W index, the diversity index family A, (Patil & Taillie, 1976, 1979), which is easy to calculate and to whom all diversity indices belong, is likely to be preferred for its desirable properties, in particular for the possibility of drawing diversity profiles which allow a continuum of analysis between the two extremes of species richness (species count) and evenness (Simpson's index). The S-W index is just a single estimate point mixing up these two fundamental aspects of diversity, and it does not say much by itself. What is important for comparing communities in time and space is, instead, the summary of diversity indices through the diversity profile to look at how the mixture of diversity components is changing in going from richness to evenness.This diversity spectrum is an important property of each community that, unfortunately, has been neglected in biodiversity research. This could be, instead, the basis to better understand what is behind the observed changes in community diversity. An example of application you may find it in my profile in a rather old paper "structural analysis of phytoplancton communities...."

For comparing H value between communities, using Renyi diversity numbers is advisable. See Tóthmérész B. 1998 – On the characterization of scale-dependent diversity – Abstracta Botanica, 22: 149–156.

As Alex Baumel says above Jos (2006) points out that the S-W index is an entropy and in order to calculate the number of equally common coral species you would take the exponent of the S-W index figure you calculated (2.85) which equals 17 equally common species of corals.

Shannon-Wiener index, along with Simpson index, has been widely used in the ecological literature as a quantitative measure reflecting the number of different types of species existing in a dataset, and concurrently takes into account the how evenly distributed the individuals are among those types. However, the down side about Shannon-Wiener index is that it couldn't stand on its own, and somehow needs another type of index used as a point for comparison, whereas the Simpson index is considered an independent index, which means it can stand on its own.

Regarding your result, a Shannon-Wiener diversity index of 2.85 indicates moderate diversity of corals. Simpson index must also be calculated for this will give you a general idea regarding dominance. The relationship between dominance and diversity is stated as follows: Low dominance indicates high diversity, whereas high dominance indicates low diversity. In your case, since 2.85 tells us that the diversity of the corals is moderate, then the dominance of the different species of corals in the area are comparable or relative to one another.

Hope this helps! Good luck!

The two main indices used to quantitatively measure diversity is the Shannon-Wiener Index and the Simpson index. The two indices rely on different concepts to measure diversity. The Shannon-Wiener Index heavily relies on uncertainty. This means that the more diverse the area, the lower the probability of correctly guessing the species of a random organism from the area. This is in contrast to Simpson's index which measures the dominance in the area. This means the more diverse the area, the lower than probability of obtaining two organism from the area which are both of the same species. Now, the actual number which u have obtained from the Shannon-Wiener index is not useful unless you compare it with the value obtained from a different area. This means that the Shannon-Wiener Index is useful for comparing the diversity between two or more areas. As a stand alone value for diversity, it would not tell a lot about a community. If you do not plan on comparing the diversity in the are with another area, then it is better to use the Simpson's Index as the value obtained from it will denote the dominance in the area. The closer this value is to zero, the more diverse the area is.

I would like to repeat again: H index without comparison is less valuable, than you imagine. 1. You should compare it with H index of similar community, or the same community in different habitats, etc. 2. As such, H index have no statistics. Look at Renyi index, it's for comparison diversity and gives you probability - then you may say, that H = 2.85 is significantly more than H = 2,45 (or not)

Sorry, originally this index is with a log 2 base. Be careful when comparing, as differences exist. there are programs to calculate H in any log base; DivOrd is among these.

Also will depend n the method of data collection. So compare with other studies on coral reefs... the value 2 to 3 is very common to find in reefs. If you have an access to JSTORE, try this: http://dx.doi.org/10.2307/1934796. If not - they put good info also in abstract.

Again, the S-W index is just a single estimate point mixing up the two fundamental aspects of diversity, i.e. richness and evenness, and it does not say much by itself with its absolute numbers. What is important for comparing communities in time and space is, instead, the summary of diversity indices through the diversity spectrum profile to look at how the mixture of diversity components is changing in going from richness to evenness. In this respect, the diversity index family A, (Patil & Taillie, 1976, 1979), easy to calculate and to whom all diversity indices belong, is likely to be preferred for its desirable properties, in particular for the possibility of drawing diversity spectra profiles which allow a continuum of analysis between the two extremes of species richness (species count) and evenness (Simpson's index). The diversity index family has been proposed at the end of 70'; do not be afraid to use it, even if it is old it does not mean it is rubbish! This diversity spectrum is an important property of each community that, unfortunately, has been neglected in biodiversity research. This could be, instead, the basis to better understand what is behind the observed changes in community diversity. An example of application you may find it in my profile in a rather old paper "structural analysis of phytoplancton communities...."

Shannon-Wiener index is the most widely index which used in marine biodiversity. is it vary between 1-5. 1 shows low diversity and 5 shows high diversity. but is should be compared with other diversity index like Margalef, Pielou or Hill.

As many others have said before, one single value does not tell much. Diversity indices are used to compare various sites, times etc. A good read is the oikos-paper (http://loujost.com/Statistics%20and%20Physics/Diversity%20and%20Similarity/JostEntropy%20AndDiversity.pdf) by Lou Jost mentioned above as well as the other stuff about indices on his webpage: http://www.loujost.com/Statistics%20and%20Physics/Diversity%20and%20Similarity/DiversitySimilarityHome.htm (highly recommended). It is good material about diversity an such with easy to follow examples.

If only one Bill Gates survived in this world then he will be only one the richest as well as the only one poorest person survived. Which adjective would you want to adore him that´s upto you.

Shannon-Weiner index is only abstract value is poor connected with biological and ecological reality... think more about your goal in study....

To make more sense of this index number in biology, you can convert it into the effective number of species (ENS), which is the real biodiversity and allows you to compare the biodiversity with other communities. A community with Shannon index of H has an equivalent diversity as a community containing equally-common species of exp(H), the ENS. For example, if you got a Shannon index of 2.85, this number can be converted into ENS that is exp(2.85) = 17. This means that a community with Shannon index of 2.85 has an equivalent diversity as a community with 17 equally-common species. In this way you can compare biodiversity among communities.

http://www.loujost.com/Statistics%20and%20Physics/Diversity%20and%20Similarity/EffectiveNumberOfSpecies.htm

According to Legendre and Legendre 2013 p 283, the diversity index H (you can call it « entropy or f oder 1») can be interpreted in probabilistic terms, and refers to : «the uncertainty about the identity (species) of an organism picked at random from the sampling unit». H is small (low H values) when the unit is dominated by a few species, or when the local richness (species number) is small. You always need to report de log base used to calculate H, and be consistent about it.

Just to correct above in line 2 : should read «entropy of order 1)

The Shannon (better than S-W) diversity index (H') measures the degree of uncertainty in a community and has 2 main parameters: richness (S, # of species) and species abundances. In order to understand the meaning of a given value of H', you should also calculate the evenness E (or equitability): E= H' / H'max, where H'max is the log of the # of species in the community (S). This will give you a better understanding of the obtained value of H' (H'obs). If E is close to 1.0, this means that equitability is higher (all species in the community are represented by a similar # of individuals) and therefore H'obs can be considered higher.

You should also pay attention to the type of logarithms (ln, log10, log2) used before making any comparisons.

Cheers,

JE

The Shannon-Wiener diversity index (H) is a measure of diversity that combines species richness (the number of species in a given area) and their relative abundances. It tells the level of diversity in that particular area, i.e. it is possible to say the diversity is low or high (since H generally ranges between 0 and 5). H also helps to compare diversity between communities within an area/ecosystem and diversity between different areas (e.g. A1 and A2). Species richness is the most commonly used measure of diversity, but H is strong indicator of diversity.

Dear Deepthi, It is very important to note that when Robert MacArthur introduced the Shannon-Weiner index into ecology he was calculating the diversity of *processes* not population counts. Unfortunately, in the early 1960's attention devolved into using the index on population counts or biomass stocks. This was a decidedly retrograde movement.

If one reverts to MacArthur's original intention, one discovers that the diversity of processes can be parsed into complementary terms that signify the degrees of constraint and flexibility, respectively . In fact, the persistence of sustainable ecosystems appears to involve a rather predictable balance between these opposing attributes .

Whence, Shannon-Weiner-like indices can be of invaluable importance in assessing ecosystem health.

Best wishes,

Bob Ulanowicz

Bob,

I cannot get these files:

404 - File or directory not found.

The resource you are looking for might have been removed, had its name changed, or is temporarily unavailable.

No other way to have them?

Bob, I also failed to connect for downloading. Please post these foles to RGate.

What Bob said really delighted me. Thanks Bob. Indeed, as land-use transformation is becoming a main global driver given the worldwide changes to forests, farmlands, waterways, and air (Millennium Ecosystem Assessment, 2005; Turner II et al. 2007), the problem we face is how a “static” and “ordered” landscape condition in social-ecological landscapes, provided by the cross-scale intersections of land use, plans and norms (order) can be made sustainable in face of unpredictable disturbance and change (disorder) (Zurlini et al., 2012). The apparent paradox that disruption processes of the existing order (i.e., disorder) and persistence processes (i.e., order, stability) always coexist in living systems is addressed by the concept of resilience, defined as the amount of disturbance a system can absorb without shifting into an alternative state and losing function and services (Carpenter et al. 2001; Walker and Salt 2006). Such a concept seeks to explain how disorder and order usually work together, allowing living systems to assimilate disturbance, innovation, and change, while at the same time maintaining characteristic structures and processes (Westley et al. 2006). Entropy measures address such problems and have a long tradition in ecology (Ulanowicz 2001). That is why we used a further derivation of the Shannon-Weiner index, i.e., the ‘‘normalized spectral entropy’’, an entropy-related index able to describe the degree of regularity (orderliness) within an ecological time-series based on its power spectrum (Zaccarelli et al. 2012). We used ‘‘normalized spectral entropy’ to estimate the adaptive capacity, that is the capacity of a system to adjust to changing internal processes (plant succession, management practices) and external forcing (rainfall, temperature, climate change, exchange rates) and thereby allow for development within the current stability domain, along the current trajectory (Carpenter and Brock 2008; Folke et al. 2010).

Again, thanks a lot Bob!

@ Robert Ulanowicz

Thank you for the new perspective you gave me with your answer!

@ Linas Balciauskas

@Zaal Kikvidze

and any other who can't download the files that Robert proposed, don't click on the link, just copy-paste the url from the text or try these:

http://people.biology.ufl.edu/ulan/pubs/FISPAP.pdf

http://people.biology.ufl.edu/ulan/pubs/Dual.pdf

Southwood, T.R.E. and Henderson, P.A. (2000): Ecological Methods. Blackwell Science Ltd. contains a very detailed, comprehensive contribution to this subject. It helps also to understand and interpret the Shannon-Wiener diversity index and its value range. It is particularly suitable for beginners.

My apologies to Zaal and Linas for their not being able to download the papers. My thanks to Alexis for setting us aright. I should not have used the conventional bent brackets to delimit the URL.

Thank you, too, Giovanni for your encouraging words. Yes, the indices can also be applied to landscape and dynamical systems. A very early attempt of mine to do so can be found at :

http://people.biology.ufl.edu/ulan/pubs/Landscpe.PDF

(I hope this one works! :)

I second the suggestion to look at papers by Lou Jost, including conversions to effective number of species. I find his work really helpful http://www.loujost.com/Statistics%20and%20Physics/Diversity%20and%20Similarity/EffectiveNumberOfSpecies.htm

Unless there is a really persuasive reason to report H', I never bother. When I'm interested in alpha diversity, I find the more direct measures of evenness (I like Simpson's) and richness (S) give a better sense of what is going on than a blended index value like H'.

Various indices have been proposed to measure diversity within ecosystems. What index you use depends on what are you interested in comparing. If you order the species you encoutered from most common to rarest, you can make a graph showing the number of individuals of each. Now, how long is the list? What is the shape of the graph? Do you see gradual, slow decrease in abundance, or are there a few abundant and many rare species, or just a handful of common ones? Are you interested at all in the long tail of rare species? Or is your focus on the relationships among the most abundant? What indices have been used in similar projects? Most importantly, are you aware of the limitations and potential artifacts of every index you want to use? One last point: Lou Jost's website is very useful.

I would add that also regardless of the index used, is this not a simple measure of diversity, in turn, descriptive of population counts that does not say much of the interrelationships and of the ongoing processes? Robert said that "when Robert MacArthur introduced the Shannon-Weiner index into ecology he was calculating the diversity of *processes* not population counts".It's really worth addressing this question, what is the real goal? One suggestion, there are goals in science that are not anchored to big questions and get lost in a thousand streams of discussion without bringing anything. To me this is one of them. We have been discussing about which diversity index was the best for at least three generations of scientists. Can we now focus on something more relevant?

Basically the index is a reflection of the congenial/stressful condition where the community is thriving. However, unless few more data are provided, it is difficult to compare the situation.

You may speculate on this by different ways....

Depends a lot. I suggest you do the analysis of diversity profiles, to avoid the mistakes of the Shannon index that gives much value to species richness.

you can use this book: Environmental assessment of Estuarine Ecosystems

There are many samples to work with ecological indices

@Robert Ulanowicz on Jan 21, 2014

Sorry for so late response. But I got the papers, very interesting, thank you!!!

Can Shannon's index be used as diversity index in a population of wheat genotypes all of the same species?

@Muhammad Sajjad

Yes, technically Shannon's index can be applied to any set of identities (categories such as species, genotypes, etc) provided you have their abundance data.

But what for? To compare with what?

@Zaal Kikvidze 

Thanks dear Zaal . I have a population of 100 wheat accessions and I divided it into three subpopulations viz pre-green revolution, post green revolution and post-veery.  I scanned these populations with 44 SSRs.  Can I compare these three subpopulations based on Shannon Index?

@Muhammad,

Yes, you can, You expect that pre-green revolution diversity be higher?

Who downvoted the splendid response of Robert Ulanowicz clearly has a very limited view of biodiversity. What Robert has written is a clear warning to see beyond their noses and simple counts of species like many, too many unfortunately still do when they address "biodiversity" through for instance the Shannon-Weiner diversity index , and look instead at the processes as it was the original intention of MacArthur. There are many, too many papers of this kind, especially in marine biology, published on biodiversity that bring no contribution to knowledge, but on the contrary, they create confusion, noise and chaos and only serve to increase the impact factor and citations of their authors. I can provide a lot of examples in this respect, and this is a clear example of the current misuse of diversity indices.

My dear @Gianni, I do must quote YOU: "Who downvoted the splendid response of Robert Ulanowicz clearly has a very limited view of biodiversity." Nothing to add dear friend!

My dear @Ljubomir, what do you mean by this? Please let me know.

Dear @Gianni, I do not like downvoters without the explanation for! Even then, You may write a critique on response that You do not like, but not to down vote!

It is true that biodiversity is not just the number per se. When we talk about a biological diversity, it means there are interconnected aspects of species as individual and as composite community in the system. However, because you use the Shannon index as a tool you have to address both the richness and evenness of a given ecosystem for your result. ID 2.8  is relatively high (some studies proposed >2.5 and others proposed >3 for good diversity), it implies that the species in the site  high/moderate (depending on the rank that you used to address your output)  distributed or increases across the study site. so the index is an indicator used to determine that the site have low, moderate, or high species diversity.

Acknowledging all weakness of Shannon-Weiner diversity index and many more like this, I would like to reply directly to the post, i.e., “I have calculated the Shannon-Weiner diversity for coral species and have obtained 2.85, what does this value infer about the diversity of the corals?” Significance of Shannon-Weiner diversity depends on the maximum possible diversity which is obtained by calculating natural logarithm of number of species and calculating evenness by dividing calculated by dividing obtained diversity index (H) by maximum possible diversity as, E=H/Hmax. These two values point out diversity richness or almost same numbers of species.

To me it appears that calculated species diversity is moderate to high in the system.

It represents the diversity of coral reefs in the study site in relation to the total diversity of coral species identified. This index can be helpful to correlation the role of coral species on diversity of aerobic microorganisms and other aquatic species.

Generally, H index result of between 1 to 3 is consider to be at moderate species diversity.

The applicability of the Shannon-Weiner index has been established in many studies and a balance is provided by comparing it with other indices. There is no perfect index. The index is used to reduce arbitrariness. So in context the value provides an estimate of the relationship between the counts and spread. At 2.85 Shannon-Weiner is saying the diversity is moderate and points in the direction of understanding why this is so in relation to environmental/ecological factors prevalent at teh time of samplin

you have to compare it to shannon index of other area and then you can say that which area is more diverse. which area has more value for shannon that are would be more diverse.

My worry is, at what point (value) do you say it is low, moderate or high? is there any graduation to help any person interpret  the result? what are the upper and lower limit of moderate. 

@Afam Anene, this depends on the value "typically" obtained in the communities you work with.  In temperate secondary grasslands H' typically reaches value between 4 and 5, whilst in the forests of the same zone it is 1-2... So you must know the typical H' obtained in your system. If there is no such data, you can compare to a similar system for which the typical H' is known

It always needs to be compared with some other values rather than standalone. It is really difficult to interpret the single value only.

please read much about Shannon and Simpson indices and its standard values too.

Please do not use "Shannon-Weiner diversity index". This is a "Shannon index" or "Shannon Wiener index", not Weiner!!!

• DOI 10.1046/j.1466-822X.2003.00015.x

The value of shannon and weiner diversity index vary when it range more than 3 it shows more diversity. when dominance is low diversity is high and reciprocal . The range from 2 and above show moderate diversity. Simpson index value ranges from 0-1. If value ranges towards 1. It mean high diversity.

Dear Deppthi,

Shannon index is ones of the many alpha ecological indices, they are tools to convert your multivariate data to a univariate universe with the goal to simplify the ecological analysis. However, they are tools to evaluate local diversity; therefore comparisons to evaluate how diverse are your sampling site must be done with expressions as Ln(S) or true diversity that evaluate the diversity locally because in your community is being reflected the environmental conditions, local heterogeneity, habitat biological transformations and the interaction of all these factors.

it means there are more species and the species abundance is more even.

Yes, I would like to think that diversity values (Shannon) could range from 0 to any value depending on the taxa and depending on the community. Not all taxa are species rich. Gastropoda for example is a species-rich taxon. But this also depends on the character of a community. As far as standards, i hope literature has something for the major taxa.

The value 2.85 indicates moderate diversity. This index is based on proportional of number of individuals against number of species. There is no limit to identify the best diversity as fir evenness index where the range is located between 0 (for dominance case) and 1 for well distribution of number of individuals among the species accounted. For example in A population if the No. of species equal 5 and each represented by 10 individuals, i.e., total equal 50, the diversity will be the maximum H, but less than that of population B in which the No. species is 6 represented by 11 individuals. So to evaluate the value obtained it will be better to compare with available values on temporal and spatial basis.

Take into account that Shannon index is expressed in a logarithmic scale. That means that your 2.85 value implies a much greater biodiversity than a 1.85 value, and a much lower biodiversity than a 3.85 value. The units of the Shannon index are nats (if you use natural logarithms) or decits (if you use base 2 logarithms). In ecology, sometimes it is justified to transform numbers into logarithms, for example in regression analyses. However, you should not transform numbers into logarithms for no reason, and that is what you do when you use the Shannon index. I suggest that you take a look at Hill's numbers. One of such numbers is N1 = exponential of the Shannon index. When you use it, a biodiversity value of 2 is half as large as a biodiversity value of 4. The units in which N1 is expressed are species, which is much more intuitive. When using N1 for biodiversity (= heterogeneity) you can accompany it with G2,1 for evenness.

To interpret a Shannon's entropy value of 2.85 (let's say bits, assuming you used log2), I would divide this value by the Log2 of the total number of species in your sample set (this is known as relative entropy=Hobs/Hmax). This ratio goes from 0 to 1. If you get a value close to 1, that means that the species in your sample set are randomly distributed, so there is no way to predict anything about species a by observing species b. If you get a value close to zero, that means that your sample set is totally predictable, and by observing a given species, let's say sp. a, you could predict a lot about spp. b, c, d...n, in other words, your data are redundant. I like to think about this property of Shannon's index as a way to measure how connected the species or the elements are in a heterogeneous set. Of course, these operations and interpretations are relative to your dataset only.

Also, I like the idea of calculating the Effective Number of Species. This is another way to see how much redundancy you have in your sample set. For instance, if you find that the ENS is less than the observed number of species in the sample set, that means that in theory you only need to observe the equivalent to the ENS because the remaining species don't add additional information to the pattern observed.

I had a lapsus: base 10 = decits; base e = nats; base 2 = bits.

any relationship with species diversity (H’ [log2]), richness (d), evenness (J’) and dominance (1-λ’) , i have high species diversity with low evenness, can any body explain the reason???

Measuring species diversity by using a single index like Shannon-Wiener is convenient for purposes of comparison among communities. I agree with Leszek A. Błędzki that you have to make a standardization of sample size from each communities before compare them. Large sample tends to result higher value of index diversity than the small one. If you study only one community without any purpose to compare with the other, it would be more useful to describe the community by using rank-abundance diagram as a description of community composition.

As with Leszek A. Błędzki suggestion, data has to be standardised if comparing samples. However, SW is an alpha diversity measure. It is more suited to investigating within a sample rather than across samples and time (Beta diversity). The Index itself is only a relative measure. It really does need to be considered within the context of other measures such as evenness and dominance (and, please choose the informatic index which best suits the data you have. Don't try and squeeze the data into the index just because it "sounds good" ).

Similarly, investigations of skewness, using simple graphical methods (i.e., charts of species x abundance - not species accumulation curves) are important at understanding the value of "2.85" within the context of the ecosystem/sample.

Finally, the limitations of your data (e.g., variation in observability) must also be understood and must play a part in the interpretation of results.

Many of these alpha diversity indices are often used to describe what they were never designed to do. I strongly recommend that people take time to study the texts of Magurran or Hayek and Buzas. These informatics can provide a substantial amount of descriptive information about samples if used correctly.

Shannon Wiener Diversity Index: Will it be useful to calculate the diversity index and evenness of gastropod species. While computing, do we need to compute only the species of gastropods in the regions, or all other species. All other means is it animal / invertebrate/ gastropod species? Please explain.

When comparing the numbers of species observed at different sites, does the higher H' value indicate greater diversity?

Rashid, the SW index is an alpha diversity measure. It is only relevant to the assemblage being measured within a site (it is an index of the relative abundance of species within a sample). If you make enough assumptions about several sites and argue they are homogeneous or similar, you can make an argument for comparison. But I would strongly suggest you use Beta diversity methods for comparing spatially or temporally diffuse sites.

Thanks Eddy.

Realliy interesting answers!

Shannon's Index of 2.85 indicates that coral diversity is high. The exp(2.85) is 17.28 (approx. 17 species). Shannon's Index, which is widely used to compare biodiversity of different sites, is merely a value. The exponential of the index value only gives some idea about the diversity. True Diversity (effective number of species) is a better measure of site-level diversity than Shannon's Index.

Shannon Index takes into account both abundance and evenness of species present in the community. A high value of Shannon Index “H” would be a representative of a diverse and equally distributed community and lower values represent less diverse community. A value of 0 would represent a community with just one species. Hence the community with higher Shannon’s diversity index is the most diverse community.

Thank you Sawar Khan and Satya P.S. Kushwaha , your response was very helpful

informative.....thanks to all participants

its informative....

Thank you for explanations.

Always diversity is inversely proportion to richness

I am getting Shannon Index “H” values in 4.0 to 6.5 range in PAST software for quantitative data, How to interpret it? as many paper showed, it ranges between 0 to 1