Dear Rodrigo, that is pretty helpful, and an interesting topic, too (biodiversity ~ restoration). Most interesting is the fact that Tropek et al. used relative cover for the vascular plants. This is something I always was afraid of, as the methods clearly (?) depend on abundance "counts". Anyway, this is another problem :) Actually, I already asked Chao and Jost etc. but never got any answer. What a pity. Thanks for your thoughts! I will now pool the dataset and refer to Gotelli & Colwell 2001 and Tropek et al. 2010. best regards from Hamburg Answer from Jens Oldeland on researchgate.net
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Eco-intelligent
eco-intelligent.com › 2016 › 09 › 23 › species-diversity-species-richness-species-abundance
Species richness, species abundance and species diversity – Eco-intelligent
September 23, 2025 - Species richness is the number of species in an area. It’s merely a numerical characteristic of an ecosystem. Species abundance is the number of individuals of each species in an area.
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Encyclopedia Britannica
britannica.com › science › environment
Biogeographic region - Species Richness, Abundance, Diversity | Britannica
July 26, 1999 - Biogeographic region - Species ... also by the relative abundance of individuals in that community. Species abundance is the number of individuals per species, and relative abundance refers to the evenness of distribution of ...
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PubMed
pubmed.ncbi.nlm.nih.gov › 17536417
Relationships between species richness, evenness, and abundance in a southwestern savanna - PubMed
By contrast, evenness usually was negatively correlated with the abundance variables, reflecting the fact that plots with high evenness generally were those where all species present were about equally uncommon. Therefore richness, but not evenness, usually was a positive predictor of places of conservation value, if these are defined as places where species of interest are especially abundant.
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Nature
nature.com › scitable › knowledge › library › characterizing-communities-13241173
Characterizing Communities | Learn Science at Scitable
Species richness is simply the number of species in a community. Species diversity is more complex, and includes a measure of the number of species in a community, and a measure of the abundance of each species. Species diversity is usually described by an index, such as Shannon’s Index H'. ...
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Dear Rodrigo, that is pretty helpful, and an interesting topic, too (biodiversity ~ restoration). Most interesting is the fact that Tropek et al. used relative cover for the vascular plants. This is something I always was afraid of, as the methods clearly (?) depend on abundance "counts". Anyway, this is another problem :) Actually, I already asked Chao and Jost etc. but never got any answer. What a pity. Thanks for your thoughts! I will now pool the dataset and refer to Gotelli & Colwell 2001 and Tropek et al. 2010. best regards from Hamburg
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Both Abundance and Incidence are population ecological concepts that are concerned with relative exemplification of a species in a given ecosystem. The two terms relate to species richness and diversity.  As observed in Ecology Letters, (2005) 8: 148–159 the number of species recorded in a sample (or a set of samples) is very sensitive to the number of individuals or samples observed or collected, which in turn is influenced by the effective area that is sampled and, in replicated designs, by the spatial arrangement of the replicates. Thus, many measures reported as ‘species richness’ are effectively measures of species density: the number of species collected in a particular total area. For quadrat samples or other methods that sample a fixed area, species density is expressed in units of species per specified area. Even for traps that collect individuals at a single point (such as a pitfall trap), there is probably an effective sampling area that is encompassed by data collection at a single point.  Chao et al., 2005. A new statistical approach for assessing similarity of species composition with incidence and abundance data. Ecology Letters, (2005) 8: 148–159
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ScienceDirect
sciencedirect.com › science › article › pii › S1470160X20308505
Species richness, not abundance, drives ecosystem multifunctionality in a subtropical coniferous forest - ScienceDirect
September 7, 2020 - Our results indicate that the direct effects of species richness on EMF were stronger than the effects of woody individual abundance, and species richness increased with increasing EMF.
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Wikipedia
en.wikipedia.org › wiki › Diversity_index
Diversity index - Wikipedia
1 week ago - For example, species richness (usually noted S) is simply the number of species, e.g. at a particular site. Richness is a simple measure, so it has been a popular diversity index in ecology, where abundance data are often not available.
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Biology LibreTexts
bio.libretexts.org › bookshelves › botany and horticulture › botany (ha, morrow, and algiers) › 5: ecology and conservation › 5.2: communities and ecosystems
5.2.4: Biodiversity in Ecosystems - Biology LibreTexts
July 28, 2025 - The variety of these species is called species richness. Relative abundance is the number of individuals in a species relative to the total number of individuals in all species within a habitat, …
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Forest Research
forestresearch.gov.uk › home › tools and resources › forestry and tree health resources › species diversity
Species diversity - Forest Research
May 10, 2024 - Species diversity is measured through a combination of species richness (the number of species present) and species evenness (the abundance of each species).
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Biology LibreTexts
bio.libretexts.org › campus bookshelves › university of california davis › bis 2b: introduction to biology - ecology and evolution › 2: biodiversity
2.2: Measuring Species Diversity - Biology LibreTexts
October 23, 2022 - Species richness is a measure of the number of different types of species in an ecosystem. A large number of different species in a habitat represents a higher species richness, and an overall more diverse ecosystem.
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Wikipedia
en.wikipedia.org › wiki › Species_richness
Species richness - Wikipedia
December 18, 2024 - Species richness is the number ... or region. Species richness is simply a count of species, and it does not take into account the abundances of the species or their relative abundance distributions....
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Oreate AI
oreateai.com › blog › understanding-species-richness-and-abundance-a-deep-dive-into-biodiversity › 119491caef4e37831f31cc65c41d7d8c
Understanding Species Richness and Abundance: A Deep Dive Into Biodiversity - Oreate AI Blog
January 15, 2026 - Species richness refers to the sheer number of different species present in a given area. Imagine walking through a lush forest; each unique bird call or rustle in the underbrush represents a different species contributing to that ecosystem’s ...
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Hankstevens
hankstevens.github.io › Primer-of-Ecology › diversity.html
14 Diversity | Primer of Ecology using R
These two samples have different ... single species. Now we’ll calculate our different measures of species diversity. Species richness is simply the number of different species in the sample....
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Quora
quora.com › What-are-the-differences-between-species-richness-and-species-evenness
What are the differences between species richness and species evenness? - Quora
Answer (1 of 2): Species richness is simply the number of species in a given community. Species evenness is the number of species and relative abundance of those species individuals in a given community.
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Quizlet
quizlet.com › 535692870 › biology-species-abundance-vs-richness-flash-cards
Biology - Species Abundance vs. Richness Flashcards | Quizlet
Study with Quizlet and memorize flashcards containing terms like species abundance, species richness, biodiversity and more.
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I think neither of these responses fit perfectly into any of the standard GLM link functions. Taking a pragmatic approach it is probably sufficient to pick a link function that is broadly doing the right thing.

Your raw data is from a multinomial distribution, and Richness, $R$, is the number of categories with a score of 1 or more. Although this is count data, it isn't quite the same as the normal sort of count data. The most striking difference being that you can never have a count of zero. As pragmatic first attempt, I would consider modeling $(R-1)$ using a poisson link function. The handwaving reasoning here could be this: If you were catching animals at a random rate for a fixed length of time, the number caught would be modelled well by Poisson. You are catching a fixed number of animals, but at a random rate the type of animal changes. If it wasn't for the fact your return to species already seen, this would be quite a good match.

For diversity, things are even less intuitive. However, the diversity is a sort of average of the abundance ($p_i$) of each species, and as such is bounded by $[0,1]$. This suggests that you could probably treat it as a proportion and use a logit link function.

Advanced Alternative

If the pragmatic matching of support and "looks approximately right" approach is not satisfying, it appears there is another way. I don't know much about this, but there is something called the *Multinomial Diversity Model" which is designed to deal with these sorts of problems. It is described in this paper, http://www.ncbi.nlm.nih.gov/pubmed/23185889 but I have no idea how popular it is.

It is, however, implented in R and availble on CRAN as MRM, apparently by the author of the above paper. It includes a spider data set used as an example in the help:

library(MDM)
data(spider6)
fit0 <- mdm(y2p(spider6[,1:6])~1,data=spider6)
fit1 <- mdm(y2p(spider6[,1:6])~Water,data=spider6)
fit2 <- mdm(y2p(spider6[,1:6])~Water+Herbs,data=spider6)
fit3 <- mdm(y2p(spider6[,1:6])~Site,data=spider6,alpha=TRUE)
anova(fit0,fit1,fit2,fit3)
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Nature
nature.com › nature communications › articles › article
Species abundances surpass richness effects in the biodiversity-ecosystem function relationship across marine fishes | Nature Communications
August 21, 2025 - However, in the tropics, species abundances surpass species richness in their effects on functioning. These latitudinal disparities can be explained by trade-offs in the relationship between abundance and per-capita productivity.
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ScienceDirect
sciencedirect.com › science › article › pii › S1470160X21010670
Abundance, species richness and diversity of forest bird assemblages – The relative importance of habitat structures and landscape context - ScienceDirect
November 25, 2021 - Broadleaf cover and distance between forest sites drive bird richness and diversity. ... Simply providing habitat structures for conservation is not a viable solution. The variability in the amount and configuration of broad habitat types in the landscape, together with their structural complexity, influence observed biodiversity patterns. When considering structurally similar sites of the same habitat type, the variability in the abundance, species richness or diversity of organisms may be explained by the landscape context.
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Coastal Wiki
coastalwiki.org › wiki › Measurements_of_biodiversity
Measurements of biodiversity - Coastal Wiki
A leading principle in the richness and evenness indices is that 'all species and individuals are considered equal' [5]. This means that different species count in the same way. No specific values or weights are assigned to species, except for numbers of individuals per species (species abundances).