hegyi: Hegyi index - Hegyi 1974

In johngodlee/compInd: Forest tree-tree competition indices

Hegyi index - Hegyi 1974

Description

Hegyi index - Hegyi 1974

Usage

hegyi(dbh, dist, focal_dbh)

Arguments

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

Details

A spatially explicit competition index which takes into account DBH and distance of competitor trees. The iterative Hegyi index is a variant which picks competitors based on minimum distance of neighbouring trees within arc zones around the focal tree.

Value

value of competition index for focal tree

References

Hegyi, F., 1974. A simulation model for managing jack-pine stands. In: Fries, J. (Ed.), Growth Models for Tree and Stand Simulation. Royal College of Forestry, Stockholm, pages. 74–90.

Examples

data(bicuar)
nb <- nearNeighb(bicuar$x, bicuar$y, bicuar$stem_id, k = 4) 
lapply(nb, function(x) {
  nb <- merge(x, bicuar, by.x = "nb", by.y = "stem_id")
  focal_diam <- unique(bicuar[bicuar$stem_id == nb$focal,"diam"])
  hegyi(nb$diam, nb$nb_dist, focal_diam)
  })

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