B.S.F. or B.Sc.F. Bachelor of Science in Forestry Forest Mensuration and Timber Inventory 1 — Questions and Answers
Question 1: Diameter at breast height (DBH) in the United States is measured at what height above the ground?
- 3.0 feet
- 4.5 feet (Correct answer)
- 5.0 feet
- 6.0 feet
Correct answer: 4.5 feet
US standard specifies DBH is measured at 4.5 feet (1.37 m) above the uphill side of the tree.
Question 2: A Bitterlich angle gauge (wedge prism) in forestry is used to:
- Measure tree height using triangulation
- Conduct variable-radius plot sampling based on tree basal area (Correct answer)
- Estimate stand age from core increment borings
- Measure crown diameter from the ground
Correct answer: Conduct variable-radius plot sampling based on tree basal area
The wedge prism uses the angle-count (Bitterlich) method to sample trees proportional to their basal area, making it efficient for estimating basal area per acre.
Question 3: The International 1/4-inch log rule, Scribner rule, and Doyle rule are all examples of:
- Site index tables
- Log volume estimation methods (Correct answer)
- Silvicultural treatment prescriptions
- Stem taper equations
Correct answer: Log volume estimation methods
These are standard log rules used in the US to estimate the board-foot volume of sawlogs based on log diameter and length.
Question 4: What does 'board foot' measure in timber commerce?
- Cross-sectional area at breast height
- A unit of wood volume equal to 12 inches × 12 inches × 1 inch (Correct answer)
- Weight of green timber per cubic foot
- Linear feet of a log
Correct answer: A unit of wood volume equal to 12 inches × 12 inches × 1 inch
A board foot is a unit of wood volume equal to 144 cubic inches (12″ × 12″ × 1″), the standard unit for measuring and pricing sawn lumber and sawlogs in the US.
Question 5: In forest mensuration, 'merchantable height' of a tree refers to:
- Total tree height to the tip
- Height to the base of the live crown
- Height to the point where the stem no longer meets minimum size or quality standards for commercial use (Correct answer)
- Height at which DBH is measured
Correct answer: Height to the point where the stem no longer meets minimum size or quality standards for commercial use
Merchantable height is the length of stem usable for commercial products, ending where the stem becomes too small in diameter or too defective for the intended product.
Question 6: Which sampling design uses plots placed at regular intervals across a forested area?
- Simple random sampling
- Systematic sampling (Correct answer)
- Stratified random sampling
- Cluster sampling
Correct answer: Systematic sampling
Systematic sampling places plots at fixed, regular intervals (e.g., on a grid), providing even spatial coverage and simplicity in the field.
B.S.F. or B.Sc.F. Bachelor of Science in Forestry Forest Mensuration and Timber Inventory 1
Diameter at breast height (DBH) in the United States is measured at what height above the ground?