dar: Diversity-Area Relationship (DAR)

In spacc: Fast Spatial Species Accumulation Curves

Diversity-Area Relationship (DAR)

Description

Extend the classic species-area relationship (SAR) to a diversity-area relationship using Hill numbers of any order q. Instead of plotting species richness vs. sites, this plots effective diversity vs. cumulative area.

Usage

dar(
  x,
  coords,
  q = c(0, 1, 2),
  n_seeds = 50L,
  method = "knn",
  area_method = c("convex_hull", "voronoi", "count"),
  distance = c("euclidean", "haversine"),
  parallel = TRUE,
  n_cores = NULL,
  progress = TRUE,
  seed = NULL
)

Arguments

x	A site-by-species matrix (abundance data recommended).
coords	A data.frame with columns x and y, or a spacc_dist object.
q	Numeric vector. Diversity orders. Default c(0, 1, 2).
n_seeds	Integer. Number of random starting points. Default 50.
method	Character. Accumulation method. Default "knn".
area_method	Character. How to estimate cumulative area: "voronoi" (Voronoi tessellation, requires sf), "convex_hull" (convex hull of accumulated sites, requires sf), or "count" (use site count as proxy, no dependencies). Default "convex_hull".
distance	Character. Distance method. Default "euclidean".
parallel	Logical. Use parallel processing? Default TRUE.
n_cores	Integer. Number of cores.
progress	Logical. Show progress? Default TRUE.
seed	Integer. Random seed.

Details

The DAR (Ma, 2018) generalizes the SAR by replacing species richness (q=0) with Hill numbers of any order. This reveals how different facets of diversity scale with area:

• q=0 (richness) recovers the classic SAR

• q=1 (Shannon) shows how common species diversity scales

• q=2 (Simpson) shows how dominant species diversity scales

Value

An object of class spacc_dar containing:

hill	A spacc_hill object with diversity curves
area	Matrix of cumulative areas (n_seeds x n_sites)
q	Diversity orders used
area_method	Method used for area estimation

References

Ma, Z.S. (2018). DAR (diversity-area relationship): extending classic SAR for biodiversity and biogeography analyses. Ecology and Evolution, 8, 10023-10038.

Arrhenius, O. (1921). Species and area. Journal of Ecology, 9, 95-99.

See Also

spaccHill(), extrapolate()

Examples

coords <- data.frame(x = runif(50), y = runif(50))
species <- matrix(rpois(50 * 30, 2), nrow = 50)

dar <- dar(species, coords, q = c(0, 1, 2))
plot(dar)

spacc documentation built on June 20, 2026, 5:07 p.m.