pointDens: Point density - Spurr (1962)
In johngodlee/compInd: Forest tree-tree competition indices

pointDens

R Documentation

Point density - Spurr (1962)

Description

Point density - Spurr (1962)

Usage

pointDens(dbh, dist)

Arguments

`dbh`	vector of DBH (diameter at breast height) measurements of competitor trees
`dist`	vector of distances from focal tree to competitor trees

Details

Calculates point density in units of dist, with the equation:

\sum_{k=i}^{n} (0.25 (k - 0.5) (D_{k} / L_{k})^2 ) / k

where k is the rank of the kth competitor by dbh value, D_{k} is the dbh of the kth competitor, and L_{k} is the distance of the kth competitor to the focal tree i.

Value

value of competition index for focal tree

References

Spurr, S. H. (1962). A measure of point density. Forest Science. Volume 8. Issue 1. Pages 85–96.

Examples

data(bicuar)
nb <- nearNeighb(bicuar$x, bicuar$y, bicuar$stem_id, k = 4) 
lapply(nb, function(x) {
  nb <- merge(x, bicuar, by.x = "nb", by.y = "stem_id")
  pointDens(nb$diam, nb$nb_dist)
  })

johngodlee/compInd documentation built on Aug. 5, 2024, 8:44 a.m.