Measurement, Analysis & Decision Support Systems Flashcards

A forester uses the two-stage least squares (2SLS) estimator instead of OLS when modeling timber supply. The most likely reason is:

Answer: Price is endogenous because supply and demand are simultaneously determined

When price and quantity are jointly determined by supply and demand, OLS estimates are biased; 2SLS uses instrumental variables to isolate exogenous price variation.

In GIS-based forest planning, what is the primary purpose of a digital elevation model (DEM) derivative called the Topographic Wetness Index (TWI)?

Answer: Predicting soil moisture patterns and potential wetland areas based on slope and upslope contributing area

TWI = ln(a/tan β) where a is upslope contributing area and β is local slope; high TWI values indicate low slopes with large catchments, predicting wetter soil conditions.

Which of the following best describes the difference between Scribner and International ¼-inch log rules?

Answer: Scribner assumes cylindrical logs; International assumes a fixed 2% taper per 8-foot section

Scribner uses a diagram method assuming a cylinder with a fixed saw kerf; International ¼-inch rule assumes 1/8-inch kerf and 2% diameter taper per 4-foot section.

A forest carbon inventory uses the stock-change method. Carbon stock at Time 1 is 450 Mg C/ha and at Time 2 (5 years later) is 510 Mg C/ha. Net ecosystem carbon balance (NECB) in Mg CO₂e/ha/yr is approximately:

Answer: 44 Mg CO₂e/ha/yr sequestered

ΔC = (510−450)/5 = 12 Mg C/ha/yr; converting to CO₂e: 12 × 3.667 = 44 Mg CO₂e/ha/yr sequestered.

A forester applies the Chapman-Richards function to model height growth over time. Which parameter controls the asymptote (maximum height) of the curve?

Answer: The asymptote parameter (A)

In the Chapman-Richards model H = A(1 − e^{−kt})^m, the parameter A sets the upper asymptote that height approaches as age increases toward infinity.

Multi-criteria decision analysis (MCDA) is used in forest planning when:

Answer: Multiple conflicting objectives (timber, wildlife, recreation, water) must be traded off without a common unit

MCDA frameworks (e.g., AHP, TOPSIS, weighted sum) allow comparison of alternatives across incommensurable objectives, making trade-offs explicit when no single metric captures all goals.

In a variable-radius plot cruise (prism or angle gauge), a 'borderline tree' situation occurs when the tree appears to be exactly at the inclusion threshold. The recommended field protocol is:

Answer: Measure the exact horizontal distance to the tree center and DBH, then calculate whether it meets the inclusion criterion

For borderline trees, cruisers should measure the exact distance and DBH, then determine inclusion using the formula DBH/distance compared to the gauge constant.