Indicator value
Encyclopedia
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 ot 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.
In other words, Ellenberg
indicator values (EIV) represents a set of seven numbers expressing the average realized niches of species along seven fundamental gradients (light, temperature, continentality, nutrients, soil moisture, pH, salinity). It is a first model of bioindication proposed and applied to the flora of Germany (Ellenberg, 1974)
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
Heinz Ellenberg
Heinz Ellenberg was a German biologist, botanist and ecologist. Ellenberg was an advocate of viewing ecological systems through holistic means.- Life :...
'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 ot 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
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. Relative abundance
Abundance
Abundance may refer to:In science and technology:* Abundance , the opposite of scarcities* Abundance , growing food with plentiful resources that will not run out -- sunshine, CO2, and waste or brine water....
is compared to frequency
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
in order to find a percentile
Percentile
In statistics, a percentile is the value of a variable below which a certain percent of observations fall. For example, the 20th percentile is the value below which 20 percent of the observations may be found...
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
Lichen
Lichens are composite organisms consisting of a symbiotic organism composed of a fungus with a photosynthetic partner , usually either a green alga or cyanobacterium...
that portrays the amount of air pollution
Pollution
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
. Indicative species can be used in ecology
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
in order to see specific biotic
Biotic component
Biotic components are the living things that shape an ecosystem. A biotic factor is any living component that affects another organism, including animals that consume the organism in question, and the living food that the organism consumes. Each biotic factor needs energy to do work and food for...
and abiotic factors on the environment as they affect the species in a specific manner.
In other words, Ellenberg
Heinz Ellenberg
Heinz Ellenberg was a German biologist, botanist and ecologist. Ellenberg was an advocate of viewing ecological systems through holistic means.- Life :...
indicator values (EIV) represents a set of seven numbers expressing the average realized niches of species along seven fundamental gradients (light, temperature, continentality, nutrients, soil moisture, pH, salinity). It is a first model of bioindication proposed and applied to the flora of Germany (Ellenberg, 1974)
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
- This doesn't work any more - link is broken *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