A study of small-plots of old-growth Douglas Fir in Oregon.
A study of small-plots of old-growth Douglas Fir in Oregon.
data("johnson.douglasfir")A data frame with 1600 observations on the following 3 variables.
rowrow
colcolumn
volumevolume per plot
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).
Floyd A. Johnson, Homer J. Hixon. (1952). The most efficient size and shape of plot to use for cruising in old-growth Douglas-fir timber. Jour. Forestry 50, 17-20. https://doi.org/10.1093/jof/50.1.17
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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 ## Not run: libs(lattice) levelplot(volume ~ col*row, dat, main="johnson.douglasfir", aspect=1) histogram( ~ volume, data=dat, main="johnson.douglasfir") ## End(Not run)
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