dave (version 2.0)

dircor: Directional mantel correlation

Description

Given a two-dimensional vegetation data frame and the x- and y-coordinates of the releves (the rows in the data frame) in geographical space, mantel correlation (function mantel in the vegan package) is evaluated at regular intervals of direction. Direction versus correlation is plotted including 95 percent confidence interval.

Usage

dircor(veg, x.axis, y.axis, step,...)
dircor2(veg, x.axis, y.axis, step = 5)
# S3 method for default
dircor(veg, x.axis, y.axis, step,...)
# S3 method for dircor
plot(x,...)

Arguments

veg

A data frame of vegetation releves (rows) by species (columns)

x.axis

This is the x-coordinate in geographical space

y.axis

This is the y-coordinate in geographical space

step

The step length in degrees, used to draw the above mentioned function

x

An object of class "dircor"

…

Further variables used for printing

Value

An output list of class "dircor" with at least the following intems:

steps

The explicit steps used in degrees, 0 - 180 degrees

mean.correlation

Mantel correlation at each step

lower.limit

The lower confidence limits

upper.limit

The upper confidence limits

Details

The method presently uses correlation as distance, as.dist((1-cor(t(sveg^2.0)))/2), as distance measure for vegetation releves.

References

Legendre, P. & Fortin, M.-J. 1989. Spatial analysis and ecological modeling. Vegetatio 80: 107--138.

Wildi, O. 2017. Data Analysis in Vegetation Ecology. 3rd ed. CABI, Oxfordshire, Boston.

Examples

# NOT RUN {
# vegetation data is taken from sveg
# the x- and y-axes are stored in object ssit
o.dircor<- dircor(sveg,ssit$x.axis,ssit$y.axis,step=40)
plot(o.dircor)
# }