dbhCorr: Diameter correlation index - Davies 2008
In johngodlee/compInd: Forest tree-tree competition indices

dbhCorr

R Documentation

Diameter correlation index - Davies 2008

Description

Diameter correlation index - Davies 2008

Usage

dbhCorr(dbh, focal_dbh)

Arguments

`dbh`	vector of DBH (diameter at breast height) measurements of competitor trees
`focal_dbh`	DBH of focal tree

Details

All else being equal, the value of diamCorr() increases as the focal tree size increases. For a given focal tree size, the value increases as average neighbour size increases. Given by the equation:

DCI_{i} = \frac{dbh_{i} \sum_{j=1}^{n} dbh_{j}}{n \overline{dbh}^2}

Value

value of competition index for focal tree

References

Davis, O., Pommerening, A. (2008). The contribution of structural indices to the modelling of Sitka spruce (Picea sitchensis) and birch (Betula spp.) crowns. Forest Ecology and Management. Volume 256. Pages 68-77.

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$focal,"diam"])
  dbhCorr(nb$diam, focal_diam)
  })

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