Indicator value

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Indicator value is a term that has been used in ecology for two different indices. The older usage of the term refers to Ellenberg's indicator values, which are based on a simple ordinal classification of plants according to the position of their realized ecological niche along an environmental gradient.[1] More recently, the term has also been used to refer to Dufrêne & Legendre's indicator value, which is a quantitative index that measures the statistical alliance of a species to any one of the classes in a classification of sites.[2]

Ellenberg's Indicator Value[]

Ellenberg's indicator values[1] were the first model of bioindication proposed and applied to the flora of Central Europe, and they have a long tradition in interpretation and understanding of plant communities and their evolution. The latest edition of Ellenberg's indicator values applies a 9-point scale for each of seven gradients:[3]

R - reaction (soil or water acidity/pH)
N - nitrogen (but really soil fertility or productivity, and not mineral nitrogen)
F - soil humidity or moisture
S - salt (soil salinity)
K - climatic continentality
L - light availability
T - temperature

Indicator values have also been published for Switzerland,[4] Great Britain,[5] France (Baseflor, SOPHY, Ecoplant) and some other floras.


Indicator Value of Dufrêne and Legendre[]

This indicator value is an integral part of the indicator value, which quantifies the fidelity and specificity of species in relation to groups of sites in a user-specified classification of sites, and tests for the statistical significance of the associations by permutation.[2][6][7]

The indicator value of species i for class j is obtained with the equation

IndValij = 100 · Aij · Bij

Here

Aij is specificity, i.e. the proportion of the individuals of species i that are in class j
Bij is fidelity, i.e. the proportion of sites in class j that contain species i

References[]

  1. ^ a b Ellenberg H. Zeigerwerte der Gefässpflanzen Mitteleuropas / H. Ellenberg // Scripta geobotanica. Göttingen, 1974. – Vol. 9. – 197 p.
  2. ^ a b Dufrene, M., and P. Legendre. 1997. Species assemblages and indicator species: The need for a flexible asymmetrical approach. Ecological Monographs 67:345-366.
  3. ^ Ellenberg H., Weber H.E., Dull R., Wirth V., Werner W., Paulisen D. Zeigerwerte von Pflanzen in Mitteleuropa [Indicator values of plants in Central Europe] / H. Ellenberg, H.E. Weber, R. Dull, V. Wirth, W. Werner, D. Paulisen // Scripta Geobotanics. – V. 18. – Verlag Erich Goltze KG, Göttingen, 1991. – 248 s.
  4. ^ Landolt E. Okologische Zeigerwerts zur Schweizer Flora / E. Landolt // Veroff. Geobot. Inst. ETH. Zurich. – 1977. – H. 64. – S. 1-208.
  5. ^ Hill, M.O.; Mountford, J.O.; Roy, D.B.; Bunce, R.G.H. (1999). Ellenberg's indicator values for British plants. ECOFACT Volume 2. Technical Annex (PDF). Institute of Terrestrial Ecology. ISBN 1870393481. Retrieved 29 May 2017.
  6. ^ De Caceres, M., and P. Legendre. 2009. Associations between species and groups of sites: indices and statistical inference. Ecology 90:3566-3574.
  7. ^ De Caceres, M., P. Legendre, and M. Moretti. 2010. Improving indicator species analysis by combining groups of sites. Oikos 119:1674-1684.
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