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Species richness is the simplest measure of biodiversity and is simply a count of the number of different species in a given area. It is referred to in equations as S. Image File history File links Information_icon. ...
Rainforests are among the most biodiverse ecosystems on earth Biodiversity or biological diversity is the variation of taxonomic life forms within a given ecosystem, biome or for the entire Earth. ...
An equation is a mathematical statement, in symbols, that two things are the same. ...
In order to account for the probability of missing some of the actual total number of species present in any count based on a sample population, the Jackknife estimate may be employed:
S=n+((n-1)/n)k where
- S=species richness
- n=total number of species present in sample population
- k=number of "unique" species (of which only one organism was found in sample population)
Similarly the equation may also be noted as:
S = E + k(n-1)/n where
- E = the summation of number of species in each sample
- k = number of rare/unique species
- n = number of sample
As well, when looking at local diversity the appropriate formula to use is:
S = cAz where
- c = a specific number for each taxa
- A = the area of study
- z = the slope perimeter
Reasons of being Commonly used
Practical Application It is proven that species richness is measurable in practice. It is one of the two components of the ecosystem's species diversity.
Existing Information A huge amount of information of pattern of species richness exists. This information can be found in academic literature. Further information on Species richness can be extracted from different kinds of database, such as museums.
Surrogary Species richness has been found to be a good surrogate for other measures of biodiversity that would be more difficult to be measured directly as species richness is positively correlated with some measures. Surrogate (from Lat. ...
Wide application 'Species richness' has been widely applied in practical management, legislation, and political discourse.
Factors affect Species Richness There is a strong inverse correlation in many groups between species richness and latitude - the farther from the equator, the fewer species can be found, even when compensating for the reduced surface area of the globe in higher latitudes. Equally, as altitude increases, species richness decreases, indicating an effect of area, available energy, isolation and/or zonation (intermediate elevations can receive species from higher and lower). Positive linear correlations between 1000 pairs of numbers. ...
Latitude, usually denoted symbolically by the Greek letter phi, , gives the location of a place on Earth north or south of the equator. ...
World map showing the equator in red The Equator is an imaginary circle drawn around a planet (or other astronomical object) at a distance halfway between the poles. ...
This article explains the meaning of area as a Physical quantity. ...
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Latitude
Latitudinal Gradient See also: Rapoport's rule and Latitudinal gradients in species diversity // Rapoport’s rule Rapoport’s rule states that latitudinal ranges of plants and animals are generally smaller at low than at high latitudes. ...
// The pattern The increase in species richness or biodiversity that occurs from the poles to the tropics, often referred to as the latitudinal gradient in species diversity, is one of the most widely recognized patterns in ecology. ...
- The species richness increase from high latitudes to the low latitudes.
- The peak of the species richness is not at Equator, however. It is deducted that the peak is between 20-30°N.
- The gradient of species richness is asymmetrical about the equator. The level of species richness increase rapidly from the north region but decrease slowly from the equator to southern region.
World map showing the equator in red The Equator is an imaginary circle drawn around a planet (or other astronomical object) at a distance halfway between the poles. ...
Area effect The latitudinal gradients of the species richness may result from the effect of area. The area at lower latitudes is larger than that at higher latitudes, leading to higher species richness at lower latitudes.
Productivity The latitudinal gradients of species richness may be result from the energy available to the ecosystems. At lower latitudes, there are higher amounts of energy available because of more solar radiation, more resources (for example, minerals and water); as a result, higher levels of species richness can be allowed at lower latitudes.
Area The relationship between species richness and area is commonly approximated as following equation: S = cAz or logS = logc + zlogA where S is the number of species (reflect the species richness), A is the Area, and z and c are constants.
The above relation explains the variation of species richness among different areas.
Sampling Species Richness may not really relate to the area size but the statistical artefact. More species can be recorded may just because more samples are collected in larger area.
Habitat diversity It is possible that larger area contain more habitats as it is said that larger area is more topographically and environmentally diverse. Therefore, there are more opportunities for more species to set up their populations due to higher habitat diversity.
Relationship between Endemism and Species Richness The levels of endemism and that of species richness are frequently positive correlated; however, in some oceanic islands, there is high levels of endemism but the levels of species richness are quite low.
Other Methods for measuring Biodiversity Other measures of biodiversity may also take into account the rarity of the taxa, and the amount of evolutionary novelty they embody. Rarities is a compilation album of rare songs as well as live songs released by the band Presidents of the United States of America in 1997. ...
A taxon (plural taxa), or taxonomic unit, is a grouping of organisms (named or unnamed). ...
Look up novelty in Wiktionary, the free dictionary. ...
Weakness As a measure of biodiversity, species richness suffers from the lack of a good definition of "species." There are at least 7 definitions, with their own strength and weakness. Still, it is easy to measure, and is well studied. In biology, a species is one of the basic units of biodiversity. ...
Species richness fails to take into consideration species evenness. Other measures of biodiversity, such as the Simpson index, the Shannon-Wiener index, and the fundamental biodiversity parameter θ of the unified neutral theory of biodiversity take species evenness into consideration. Species evenness is a measure of biodiversity which quantifies how equal the populations are numerically. ...
Simpsons Diversity Index is a measure of diversity. ...
The Shannon-Wiener Index (also called the Shannon Index or the Shannon-Weaver Index) is one of several measurements of biodiversity. ...
The unified neutral theory of biodiversity and biogeography (here Unified Theory or UNTB) is a theory and the title of a monograph[1] by ecologist Stephen Hubbell. ...
References - Kevin J. Gaston & John I. Spicer. 2004. Biodiversity: an introduction, Blackwell Publishing. 2nd Ed., , ISBN 1-4051-1857-1(pbk.)
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