marindicators (version 1.0.0)

pielouEvenness: Calculates Pielou's Species Evenness

Description

This function calculates Pielou's Species Evenness for \(j\) areas and \(i\) years.

Usage

pielouEvenness(X, groups, species.table = NULL, metric = "ABUNDANCE",
  years)

Arguments

X

A dataframe of fishery independent data derived from research vessel survey data or model output, with columns YEAR, ID, SPECIES, and ABUNDANCE. YEAR indicates the year the observation was recorded, ID is an area code indicating where the observation was recorded, SPECIES is a numeric code indicating the species sampled, and ABUNDANCE is the corresponding abundance (stratified and corrected for catchability as required).

groups

A vector indicating the species group(s) for which to calculate the indicator. If groups = "ALL", all species will be included; otherwise, each entry must be a character string matching the name of a column in species.table.

species.table

A table where the column names match the entries in groups. Column entries are species codes indicating the species from X included in each group. species.table may also include columns for other species groups; these will be ignored. If groups = "ALL", this table is not required. Default is species.table = NULL.

metric

A character string indicating which column in X to use to calculate the indicator. Default is metric = "ABUNDANCE".

years

A vector of years for which to calculate indicator.

Value

Returns a dataframe with columns ID and YEAR, and a column PielouEvenness_group for each entry in groups.

If there is no data for spatial scale \(j\) in year \(i\), indicator values is assigned NA.

Details

Pielou's Species Evenness: $$J' = -\Sigma p_i ln( p_i )/ln(S)$$ \(p_i\) is the proportion of the total sample contributed by the i(th) species and \(S\) is the number of species recorded in the sample. Pielou's Index is the Shannon-Weiner Index computed for the sample \(S\) and represents a measure of evenness of the community (Pielou, 1966).

References

Bundy A, Gomez C, Cook AM. 2017. Guidance framework for the selection and evaluation of ecological indicators. Can. Tech. Rep. Fish. Aquat. Sci. 3232: xii + 212 p.

Greenstreet SP, Rogers SI. 2006. Indicators of the health of the North Sea fish community: identifying reference levels for an ecosystem approach to management. ICES J Mar Sci J du Cons 63:573 593

Pielou EC. 1975. Ecological Diversity. Wiley, New York. ISBN 0-471-68925-4

See Also

Other biodiversity indicators: allBiodiversity, heips, hillN1, hillN2, kemptonQ, margalef, shannon, speciesRichness

Examples

# NOT RUN {
data(X)
pielouEvenness(X, groups = "ALL", species.table = NULL, metric = "ABUNDANCE", 
   years = c(2014:2019))
# }