agridat (version 1.23)

johnson.douglasfir: A study of small-plots of old-growth Douglas Fir in Oregon.

Description

A study of small-plots of old-growth Douglas Fir in Oregon.

Usage

data("johnson.douglasfir")

Format

A data frame with 1600 observations on the following 3 variables.

row

row

col

column

volume

volume per plot

Details

A study in 40 acres of old-growth Douglas-Fir near Eugene, Oregon. The area was divided into a 40-by-40 grid of plots, each 1/40 acre. The volume represents the total timber volume (Scribner Decimal C) of each 1/40 acre plot.

The authors conclude a 1-chain by 3-chain 3/10 acre rectangle was most efficient for intensive cruise work.

To convert plot volume to total volume per acre, multiply by 40 (each plot is 1/40 acre) and multiply by 10 (correction for the Scribner scale).

References

None

Examples

library(agridat)
data(johnson.douglasfir)
dat <- johnson.douglasfir

# Average volume per acre. Johnson & Hixon give 91000.
# Transcription may have some errors...the pdf was blurry.
mean(dat$volume) * 400
# 91124 

libs(lattice)
levelplot(volume ~ col*row, dat, main="johnson.douglasfir", aspect=1)
histogram( ~ volume, data=dat, main="johnson.douglasfir")