Size of VTM Sample Plots
Chris
information to determine the precise dimensions of the VTM plots. I
think the website is mistaken, as it says the plots were 132 X 33 ft,
or 40 X 20 m. 132 X 33 ft would be 40 X 10 m, not 20. Also, I've run
across at least one paper that re-sampled VTM plots using a 10 X 80 m
dimension. The VTM field manual clearly lays out a plot that is 2X1
chain, which should be 40 X 10m, but they also seem to change their
protocol depending on the vegetation type. Does anyone have
experience with this?
Ann Huber
You are right, the website is mistaken and needs to be corrected. The
Brush and Ground Cover plots are 2 x 0.5 chains, equivalent to ~40 x 10
meters (1 chain=66ft). If you look at the plot diagram in the field
manual (p.193 of the pdf), the brush and ground cover diagram is 100
squares (5 squares x 20 squares). Each square is 6.6 ft x 6.6 ft. That
is equivalent to 0.1 acres total area, or as it states on the form 1
milacre.
Here's where it gets confusing. The tree tally portion is indeed 2 x 1
chains in area, as is stated on the plot diagram (under the tree tally
box where it says Strip 2 x 1 chains). There is a second field manual
which we have not added to the website yet that may have been helpful to
you (although it should be stated more clearly on the website). Here is
a quote from that manual that describes the tree plot area: "In woodland
and timber types trees 4" and over in D.B.H. are tallied by diameter
groups on a strip 1 chain wide whose center line coincides with that of
the brush strip, thus giving a sample for an area of 0.2 acres."
There are basically 3 types of VTM vegetation plots (the manual refers
to these as "Sample Plots"): the Brush and Ground Cover Plot, the Tree
tally plot, and the Grassland Sample Plots. Brush and Ground Cover and
Tree tally data were taken on the same datasheet. The VTM website does
not have any data from grassland plots. Grassland plots are 5 chains in
length by 0.5 chains in width.
We will correct the website as soon as possible. Thank you for bringing
it to our attention.
--Ann
Ann Huber
Staff Research Associate
Ecosystem Sciences and Policy Management Dept, UC Berkeley
