shannon_index {ForestElementsR} | R Documentation |
Shannon Diversity Index for Tree Species
Description
Species diversity index after
Shannon and Weaver (1948). 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)
Arguments
species_id |
A vector of species codes, each vector element representing
a tree. Preferably, |
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
|
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. |
Value
The Shannon Index value resulting from the input data
References
Shannon CE, Weaver W (1948). The Mathematical Theory of Communication. University of Illinois Press.
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)