pielouEvenness: Calculates Pielou's Species Evenness
In marindicators: Marine Ecosystem and Fishing Pressure Indicators

Description Usage Arguments Details Value Author(s) References See Also Examples

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

1 2	pielouEvenness(X, groups, species.table = NULL, metric = "ABUNDANCE", years)

`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.

Pielou's Species Evenness:

J' = -Σ 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).

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.

Danielle Dempsey Danielle.Dempsey@dfo-mpo.gc.ca, Adam Cook, Catalina Gomez, Alida Bundy

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

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

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data(X)
pielouEvenness(X, groups = "ALL", species.table = NULL, metric = "ABUNDANCE", 
   years = c(2014:2019))

      ID YEAR PielouEvenness_ALL
1  AREA1 2014          0.3641888
2  AREA1 2015          0.3894733
3  AREA1 2016          0.3281575
4  AREA1 2017          0.4007546
5  AREA1 2018          0.4218297
6  AREA1 2019          0.2703277
7  AREA2 2014          0.3972961
8  AREA2 2015          0.4252770
9  AREA2 2016          0.3828098
10 AREA2 2017          0.4034722
11 AREA2 2018          0.3196600
12 AREA2 2019          0.3631935