Basic Mensuration/
Tree Value
Lands for Tomorrow – Fundamentals of
Forestry Course
6/28/2011
“How much is a tree worth?” -
factors
• Unique – Giant Sequoias in California
• Historic – Jackson Prayer Oak, Wye Oak,
McGuffey Ash
• Urban trees – property value, greenspace,
noise abatement, water & air pollution
abatement
Priceless Trees
McGuffey Ash
Prayer tree
Wye Oak
Factors for tree value
• Diameter
• Height/Length
• Species – Black Walnut vs. red maple
• Quality – knots in logs
• Location – cost of harvesting (conventional vs.
cable logging vs. helicopter logging)
• Market (No market = no value)
Value of a typical forest tree…
• …used for lumber, pulpwood, biomass, veneer
(plywood), poles & pilings, etc.
• Example 14” “dbh” Loblolly Pine with 2 ½ logs
(a log is 16’) has approx. 160 board foot (Int’l ¼
Rule)
• @ $150/MBF – this tree is worth $24.00 “on the
stump”
• @$ 250/MBF – F.O.B. Delivered Mill – this tree
is worth $40 at the mill – value added.
…That “ typical tree” in
context of a tract or stand
• Tree worth $24 in the woods
• Approx. 80-100 Trees per acre
• Approx. $2000 per acre
• If the sale is 40 acres, then
• Approx. $80,000 worth of standing
timber (stumpage)
How much volume is in that
tree?
• Diameter is measured at D.B.H. (diameter at
breast height)
• Allow for a 1’ stump
• Sawtimber hardwood- measure to 10” top
• Sawtimber softwood- measure to 7” top
• If tree is forked below D.B.H- count both
stems, but allow for a higher stump
Typical Log Rule Table
International ¼ Log Rule
Example: Pine Sawtimber Prices
– 1st Q. 2011
$/Cord $/Ton $/MBF
"Stumpage" price $63.75 $23.79 $148
F.O.B. Mill price $110.53 $41.24 $257
Cord (pine) = 75 cubic feet of wood or 128 cubic feet of
wood, bark and air (4’ wide x 4’ tall x 8’ long)
MBF = Thousand Board Feet (International ¼ Rule)
Sale Types
• Cut on “shares”
• Sealed Bid
• Mark trees to cut or leave on partial
harvest
• Mark boundary on clearcut
Timber “Cruising”
• Estimate of Timber Volume
• 100% Tally
• Sampling (plots)
• Examples
100 % Tally
• Measure everything that meets your
cruise objective (i.e. trees >14”)
• Larger timber
• Mark trees as you measure
• Time consuming
Sampling
• Fixed Radius
-1/10th, 1/20th, etc
- easiest to expand to per acre figures
• Prism Points
-10,20,30 BAF prisms
-quick, most common method in pine stands
Fixed Radius
• Need to know the radius…
• 1 ac. = 43,560 sq. ft.
Area of a circle = π r2
1/10th acre = 43,560 / 10 = 4,356 sq. ft.
π r2 = 4,356 sq. ft. r = 4,356 / = 37.24 ft.
• Tally any tree meeting your specifications
within a 37.2’distance of plot center
Prism Points
• Use a Basal Area Factor (BAF) prism to determine which
trees to tally on a point
• BAF- cross section of a tree stem measured in ft2
• Every tree tallied as “in” with a particular prism represents
the same BA (sq.ft.) per acre REGARDLESS of the tree size
Prism-dependent based on the BAF of the prism:
10 factor prism 10 sq. ft. BA/acre
20 factor prism 20 sq. ft. BA/acre
30 factor prism 30 sq. ft. BA/acre
Prism Points
• Any tree whose bole, once “shifted” by the prism,
remains within its original bole (look above and
below the prism) is considered to be “in” and will
be measured
Original bole
Shifted bole
Prism Points
• Any tree whose bole, once “shifted” by the prism, is outside
of its original bole (look above and below the prism) is
considered to be “out” and will not be measured
Original bole
Shifted bole
Grid System
• Want to determine the distance (chains)
between plots on a line and the distance
(chains) between lines.
Questions?
Ryan Hewitt
FIA Forester
Office/VM: 434/220-9061
FAX: 434/296-2369
Ryan.hewitt@dof.virginia.gov