Blossom (version 1.4)

agree2: Lodgepole pine basal area and canopy cover

Description

Analysis comparing measures of the proportion of basal area to the proportion of canopy cover of lodgepole pine (Pinus contorta) in 31 stands of subalpine forest in Colorado (Cade 1997).

Usage

data(agree2)

Format

A data frame with 62 observations on the following 6 variables.

pctscc

The response variable for proportion Englemann spruce.

pctfcc

The response variable for proportion subalpine fir.

pctlcc

The response variable for proportion lodgepole pine.

pctacc

The response variable for proportion aspen.

stand

The grouping variable specifying the 31 sample plots.

method

The blocking variable specifying whether the proportion was measured either for basal area (method = 2) or canopy cover (method = 1).

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

str(agree2)

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 * 3*r)
}

pairs(agree2[,1:4],pch = 21,bg = c("red","grey")[agree2$method],cex = 1.5,
upper.panel = panel.cor)