CF Forest Resource Measurement and Inventory 3 — Questions and Answers
Question 1: When using the line-intersect method for coarse woody debris, which measurement is recorded for each piece that intersects the transect line?
- Length of the piece
- Diameter at the point of intersection (Correct answer)
- Basal diameter of the piece
- Height above ground at the intersection
Correct answer: Diameter at the point of intersection
In the line-intersect method, the diameter of each piece where it crosses the transect line is recorded and used to calculate downed wood volume.
Question 2: Point Relascope Sampling (PRS) extends the variable-radius concept to measure which additional stand attribute beyond basal area?
- Canopy height distribution
- Number of stems per acre directly without conversion
- Tree volume and stand density simultaneously using angle counts at multiple heights (Correct answer)
- Species composition by crown projection
Correct answer: Tree volume and stand density simultaneously using angle counts at multiple heights
PRS uses angle gauges at multiple heights to simultaneously estimate volume, density, and other stand attributes without traditional plot boundaries.
Question 3: In LiDAR-based forest inventory, 'canopy height model (CHM)' is derived by:
- Subtracting the digital terrain model from the digital surface model (Correct answer)
- Adding ground return elevations to first-return elevations
- Averaging all return heights within a grid cell
- Counting pulse density per unit area
Correct answer: Subtracting the digital terrain model from the digital surface model
CHM = DSM (first returns, representing canopy top) minus DTM (ground surface), yielding vegetation height above ground.
Question 4: Which volume equation form uses diameter at breast height and total height as the only independent variables?
- Combined variable equation (Correct answer)
- Local volume table
- Form class volume table
- Taper equation
Correct answer: Combined variable equation
Combined variable (or standard) volume equations use both DBH and total height as predictors, contrasting with local tables that use DBH alone.
Question 5: If a 1-acre fixed-radius plot contains 12 trees of 10-inch DBH, what is the trees-per-acre (TPA) expansion factor when plot radius is 1/10 acre?
- 10
- 12
- 120 (Correct answer)
- 100
Correct answer: 120
TPA = trees on plot × (1/plot size in acres) = 12 × 10 = 120 TPA because a 1/10-acre plot expands by a factor of 10.
Question 6: Increment borers extract cores primarily to determine:
- Moisture content of heartwood
- Radial growth rate and stand age from annual ring counts (Correct answer)
- Bark thickness relative to total diameter
- Wood specific gravity for volume correction
Correct answer: Radial growth rate and stand age from annual ring counts
Increment borer cores reveal annual rings, allowing foresters to count tree age and measure past radial (and therefore diameter) growth rates.
Question 7: In the context of timber cruising, 'cruise control' or 'allowable error' specifies:
- Maximum slope correction applied to horizontal distance
- Acceptable sampling error at a specified probability level (Correct answer)
- The minimum number of plots required by state law
- Maximum deviation between two cruise methods
Correct answer: Acceptable sampling error at a specified probability level
Allowable error defines the precision target (e.g., ±10% at 90% confidence) that determines required sample size for the inventory.
CF Forest Resource Measurement and Inventory 3
When using the line-intersect method for coarse woody debris, which measurement is recorded for each piece that intersects the transect line?