Blossom (version 1.4)

fraserf: Subalpine forest tree cover data

Description

Lodgepole pine and Engelmann spruce canopy cover modeled as a function of basal area and density of the trees with least absolute deviation regression.

Usage

data(fraserf)

Format

A data frame with 31 observations on the following 11 variables.

apico

Basal area (m^2/ha) of lodgepole pine adjusted for slope of terrain.

apien

Basal area (m^2/ha) of Engelmann spruce.

apien2

Basal area squared of Engelmann spruce.

lcc

Lodgepole pine canopy cover.

scc

Englemann spruce canopy cover.

picopha

Lodgepole pine stem density (number/ha).

pienpha

Englemann spruce stem density (number/ha).

z81

The transformation lcc-.81(apico).

z105

The transformation lcc-1.05(apico).

z50

The transformation lcc-.50(apico).

z90

The transformation lcc-.90(apico).

Source

Cade, B.S. 1997. Comparison of tree basal area and canopy cover in habitat models: Subalpine forest. Journal of Wildlife Management 61, 326--335.

Examples

panel.cor <- function(x, y, digits = 2, prefix = "", cex.cor, ...)
{
    usr <- par("usr"); on.exit(par(usr))
    par(usr = c(0, 1, 0, 1))
    r <- abs(cor(x, y,method = "spearman"))
    txt <- format(c(r, 0.123456789), digits = digits)[1]
    txt <- paste(prefix, txt, sep = "")
    if(missing(cex.cor)) cex.cor <- 0.8/strwidth(txt)
    text(0.5, 0.5, txt, cex = cex.cor * r)
}

pairs(fraserf[,c(1,2,4,5,6,7)],main = "Lodgepole pine data\n with Spearman correlation coefficient",
     lower.panel = panel.smooth, upper.panel = panel.cor)