ForestElementsR (version 2.0.1)

shannon_index: Shannon Diversity Index for Tree Species

Description

Species diversity index after shannon_1948;textualForestElementsR. Note that this function calculates comparable output only when the same species coding is used for the input parameter species_id.

Usage

shannon_index(species_id, weights = 1, n_rep = 1)

Value

The Shannon Index value resulting from the input data

Arguments

species_id

A vector of species codes, each vector element representing a tree. Preferably, species_id is defined in one of the species codings supported by this package, but technically, this is not even a requirement.

weights

A vector of weights for each tree, default = 1, i.e. all trees are equally weighted. Must be of length 1 or the same length as species_id. Useful if e.g. trees should be weighted by their basal area.

n_rep

A vector of representation numbers for each tree, typically the number of trees represented per ha by each tree. Does only make a difference if it differs among the trees. Default = 1, i.e. all trees have the same representation number.

References

See Also

Other structure and diversity: assmann_layers(), species_profile()

Examples

  # Monospecific stand
  trees <- norway_spruce_1_fe_stand$trees
  shannon_index(trees$species_id)

  # Two-species mixed stand
  trees <- spruce_beech_1_fe_stand$trees
  shannon_index(trees$species_id)

  # Selection forest
  trees <- selection_forest_1_fe_stand$trees
  shannon_index(trees$species_id)

  # weigh with basal area (i.e. dbh^2)
  shannon_index(trees$species_id, weights = trees$dbh_cm^2)

  # weigh with inverse basal area (i.e. 1 / dbh^2)
  shannon_index(trees$species_id, weights = 1 / trees$dbh_cm^2)