# Palyi-Kownacki dominance index

This calculator allows you to calculate species dominance using the two indicators most commonly considered in community analyses, species occurrence and abundance.

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Created: 2023-12-02 18:26:43, Last updated: 2023-12-09 08:33:31

#### Palyi-Kownacki dominance index for the sample series

The row and column from which the matrix begins, with rows corresponding to species and columns to samples. The contents of the cells to the left and above are interpreted as the titles of the corresponding rows and columns. By default, the cell in the second column of the second row is considered to be the start of the data.
Digits after the decimal point: 2
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There is a problem of quantifying the dominance of species in ecological communities. A dominant species is a species that quantitatively dominates a community, which may be dominated by a single species or by several species. Depending on what parameters a researcher can measure, different approaches to assessing species participation are used.
The quantitative representation of a species can be assessed in terms of occurrence (number of individuals in the community, study sites or samples), biomass, or contribution to the community based on functional parameters. All these values can be converted to scores for ease of calculation and comparison.
The most commonly used indicators for assessing dominance are species occurrence or abundance in the community.

For phytocenoses, it is common to estimate the degree of dominance of a species based on projective cover (the area occupied by the species when looking at the community from above) or specific projective cover.
The index proposed by the Polish researcher A. Kownacki1 is a successful variant of dominance assessment. Kownacki, which assesses dominance in a biocenosis (phytocenosis, sample series), takes into account two indices at once, occurrence and abundance:

${D_i}={P_i}\frac{n_i}{\sum{n_i}}$,

where
$P_i=\frac{m_i}{M}$ - occurrence,
$m_i$- the number of samples (sites) in which species i was found,
$M$- total number of samples (sites), when calculating occurrence in the block of phytocenoses, a site is an analogue of a separate phytocenosis,
$n_i$ - participation of the i-th species in the community (abundance or biomass),
$\sum{n_i}$ - total abundance or biomass of individuals that make up the community (individuals of all species in all samples or on all sites).

In the calculator, the index values are given as a percentage.

1. Kownacki A. Taxocens of Chironomidae in streams of the Polish High Tatra Mts // Acta hydrobiol. 1971. V. 13, № 4.

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