Indicator value

Indicator value

This term is ambiguous:Ellenberg's indicator values are simple ordinal classes of organisms (initially plants) with a similar realized ecological niche along a gradient. The latest edition of Ellenberg's indicator values contain values on a 9 point scale for soil acidity, productivity/nutrients, soil humidity, continentality, soil salt content and light. Indicator values also exist in Landolt's Flora of Switzerland and some other floras. A substantial advance on a comparable scale to place a local flora on gradients are the climatic profiles of the french SOPHY online database.Ellenberg's indicator values have a long tradition in interpretation and understanding of plant communities and their evolution.Dufrêne & Legendre's indicator values are a measure of alliance of a particular taxon to a group of (in general) multi-species-samples.Created by Dufrêne, M. and P. Legendre the IndVal Method is used to identify the indicator value of a specific species. Relative abundance is compared to frequency in order to find a percentile that gives the best idea of this species as an indicator. There are many uses for IndVal, one being the calculating of IndVal for lichens which gives a percentage of an indicative species of lichen that portrays the amount of air pollution. Indicative species can be used in ecology in order to see specific biotic and abiotic factors on the environment as they affect the species in a specific manner.

Calculating the Indicator Value

To calculate the indicator value of a given species, the equation IndValij = Aij * Bij * 100 is used.

Aij = Nindividualsij/Nindividualsi

ij = The average amount of the species i in zone j (abundance)

i = Mean values for i in all zones



Bij = Nsitesij/NSitesi.

ij = Number of sites in zone j where species i is present (frequency)

i = Number of sites in zone j

Finally, IndValij = Aij * Bij * 100

Explanation

This compares the fidality, distribution, and abundance of a specific species to all the other zones and samples within a zone, where zones are specific to the factor being tested. For instance Zone 1 is a heavy pollution zone, Zone 2 medium pollution, and Zone 3 light pollution if one is to set up zones to obtain an indicator value of lichen abundance and fidelity in relation to pollution. 100 is mulitplied to the end result to get a percentage while a percentage of 25% or higher is usually considered indicative of the specific zone. Student t-tests and other statistical test can further establish conclusive results.

External links

*http://environnement.wallonie.be/sibw/outils/indval/home.html
*http://links.jstor.org/sici?sici=0012-9615(199708)67%3A3%3C345%3ASAAIST%3E2.0.CO%3B2-L


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Indicator species — An indicator species is any biological species that defines a trait or characteristic of the environment. For example, a species may delineate an ecoregion or indicate an environmental condition such as a disease outbreak, pollution, species… …   Wikipedia

  • indicator — ► NOUN 1) a thing that indicates a state or level. 2) a gauge or meter of a specified kind. 3) a flashing light on a vehicle to show that it is about to change lanes or turn. 4) Brit. an information board or screen in a railway station, airport,… …   English terms dictionary

  • Indicator function — The graph of the indicator function of a two dimensional subset of a square. In mathematics, an indicator function or a characteristic function is a function defined on a set X that indicates membership of an element in a subset A of …   Wikipedia

  • Indicator (metadata) — In metadata an indicator is a Boolean value that may contain only the values true or false. The definition of an Indicator must include the meaning of a true value and should also include the meaning if the value is false.If a data element may… …   Wikipedia

  • value — The importance placed on something by an individual. Value is subjective and may change according to the circumstances. Something that may be valued highly at one time may be valued less at another time. The CENTER ONLINE Futures Glossary * * * ▪ …   Financial and business terms

  • indicator — [[t]ɪ̱ndɪkeɪtə(r)[/t]] indicators 1) N COUNT: usu with supp An indicator is a measurement or value which gives you an idea of what something is like. ...vital economic indicators, such as inflation, growth and the trade gap... The number of wells …   English dictionary

  • value — A particular quantitative determination. For values not given below, see the specific name. SEE ALSO: index, number. [M.E., fr. O.Fr., fr. L. valeo, to be of v.] acetyl v. the milligrams of KOH required to neutralize the acetic acid produced by… …   Medical dictionary

  • indicator — noun 1》 a thing that indicates a state or level. 2》 a gauge or meter of a specified kind. 3》 Brit. a flashing light on a vehicle to show that it is about to change lanes or turn. 4》 Brit. an information board or screen in a railway station,… …   English new terms dictionary

  • pH indicator — Acids and Bases Acid dissociation constant Acid base extraction Acid–base reaction Acid–base titration Dissociation constant Acidity function Buffer sol …   Wikipedia

  • Vortex Indicator — The Vortex Indicator is a technical indicator invented by Etienne Botes and Douglas Siepman to identify the start of a new trend or the continuation of an existing trend within financial markets. It was published in the January 2010 edition of… …   Wikipedia

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”