B.F. Bachelor of Forestry Bachelor of Forestry Forest Mensuration 5 — Questions and Answers
Question 1: Which method of determining tree age is most accurate but also most destructive?
- Using a Pressler increment borer to extract a core
- Counting branch whorls
- Cutting the tree and counting annual rings on the stump (Correct answer)
- Using height-age curves from site index tables
Correct answer: Cutting the tree and counting annual rings on the stump
Felling the tree and counting all annual rings on a cross-section at the base is the most accurate age determination method but requires killing the tree.
Question 2: The Schumacher-Hall volume equation is an example of a:
- Single-entry volume table (diameter only)
- Double-entry volume table (diameter and height) (Correct answer)
- Local volume table based on bark thickness
- Taper equation for log scaling
Correct answer: Double-entry volume table (diameter and height)
The Schumacher-Hall equation uses both DBH and total height as predictors, making it a double-entry volume model.
Question 3: In a forest inventory, 'sampling error' is reduced most effectively by:
- Using larger diameter plots only
- Increasing the number of sample plots (Correct answer)
- Measuring trees during the dormant season
- Converting from systematic to random sampling
Correct answer: Increasing the number of sample plots
Sampling error (standard error of the mean) decreases as sample size increases, following the relationship SE = s / √n.
Question 4: What is the purpose of applying a 'taper correction' when measuring standing timber?
- To convert cubic volume to board-foot volume
- To adjust diameter measurements for the natural narrowing of the stem with height (Correct answer)
- To account for moisture content differences between species
- To standardize measurements taken at different breast heights
Correct answer: To adjust diameter measurements for the natural narrowing of the stem with height
A taper correction adjusts volume estimates to account for the fact that tree stems decrease in diameter from base to tip at varying rates.
Question 5: Which of the following describes the 'mean annual increment' (MAI) of a forest stand?
- The volume grown during the current growing season
- The total volume divided by the stand age (Correct answer)
- The difference in volume between two successive measurements
- The volume harvested per year
Correct answer: The total volume divided by the stand age
MAI is calculated by dividing the total accumulated volume (or other growth measure) by the total age of the stand.
Question 6: A 'tree list' inventory differs from a 'plot-based' cruise primarily because:
- It samples only dominant and codominant trees
- Every individual tree in the stand is located, identified, and measured (Correct answer)
- It uses aerial photography instead of ground measurements
- It relies on basal area factors rather than fixed plot boundaries
Correct answer: Every individual tree in the stand is located, identified, and measured
A tree list (also called 100% cruise or complete enumeration) records every tree individually within the area, providing a complete census rather than a sample.
Question 7: The 'coefficient of variation' (CV) in a timber cruise is used to:
- Estimate the total board-foot volume of a sale
- Assess the relative variability of plot measurements and help determine adequate sample size (Correct answer)
- Calculate the taper factor for each log
- Convert Scribner scale to International scale
Correct answer: Assess the relative variability of plot measurements and help determine adequate sample size
The CV (standard deviation / mean × 100) measures relative variability in cruise data and is used in formulas to determine the number of plots needed for a desired accuracy level.
B.F. Bachelor of Forestry Bachelor of Forestry Forest Mensuration 5
Which method of determining tree age is most accurate but also most destructive?