"Geoff Kegerreis" wrote in message
...

snip

Typically, the only reason you would use a prism is to estimate square foot
basal area, while sampling trees for volume. It can give you an estimate of
trees/acre, but it will always steer you wrong because larger trees are certain
to overrepresent themselves vs. saplings. Stick with the square, you'd be much
better off!
-Geoff Kegerreis
www.timberlineforestry.com

Geoff,
Either you are oversimplifying for Lugnut, or you slept through your forest mensuration class.
Prism cruises are commonly used for volume cruises, and if done properly, are every bit as accurate
and much faster than fixed area plots (the exception being areas w/heavy underbrush). Depending on
the distance between plots, a person can take 3-10 variable plots in the time it takes to set up and
measure one 1/10 ac. fixed plot - especially if they are square rather than circular fixed plots.
The key is to chose a BAF that "hits" an average of 3-5 trees/plot in the area to be sampled. BTW the
"multiplier factor" for each tree diameter for each BAF is readily calculated and is also published in
most mensuration texts. For instance the plot radius for a 10"DBH tree with a 10 BAF is 27.5', while
the radius for a 20"DBH tree is exactly double (55.0'). Thus each "in" 10" tree with a 10 BAF
represents 18.335 trees/ac., while each "in" 20" tree represents 4.584 trees/ac.
[43560/(3.14159*plot radius^2 )].


--

Bob Weinberger
Forest Management Consulting
Land and Natural Resource
Management Analysis

401 Cedar St.
La Grande, OR 97850

Remove "invalid" and place a dot between bobs and stuff to reply email