raster.evenness {BAT}

Maps of phylogenetic/functional evenness of species or individuals.

Description

Regularity of distance and abundance between any two species in a community using rasters of species distributions (presence/absence or abundance).

Usage

raster.evenness(
  layers,
  tree,
  distance,
  method = "expected",
  func = "camargo",
  abund = TRUE
)

Arguments

layers

A SpatRaster object of species distributions from package terra.

tree

A phylo or hclust object or alternatively a species x traits matrix or data.frame to build a functional tree.

distance

A dist object representing the phylogenetic or functional distance between species.

method

Calculate dispersion using "expected" values (default) or values based on "contribution" of species to the tree.

func

Calculate dispersion using "Camargo" (1993; default) or "Bulla" (1994) index.

abund

A boolean (T/F) indicating whether evenness should be calculated using abundance data.

Details

If no tree or distance is provided the result is the original index of Bulla with correction. Note that cells with less than two species cannot have evenness values.

Value

A SpatRaster object representing evenness in space.

References

Bulla, L. (1994) An index of evenness and its associated diversity measure. Oikos, 70: 167-171.

Camargo, J.A. (1993) Must dominance increase with the number of subordinate species in competitive interactions? Journal of Theoretical Biology, 161: 537-542.

Examples

sp1 <- terra::rast(matrix(c(NA,1,1,1,1,0,0,0,0), nrow = 3, ncol = 3, byrow = TRUE))
sp2 <- terra::rast(matrix(c(0,0,0,0,1,1,1,1,1), nrow = 3, ncol = 3, byrow = TRUE))
sp3 <- terra::rast(matrix(c(0,0,0,1,1,1,0,0,0), nrow = 3, ncol = 3, byrow = TRUE))
spp <- c(sp1, sp2, sp3)
tree <- hclust(dist(c(1:3), method="euclidean"), method="average")
tree$labels = c("Sp1", "Sp2", "Sp3")
names(spp) = tree$labels
raster.evenness(spp)
raster.evenness(spp, tree)