SAF Field Survey & Data Collection 3

Question 1

When measuring slope distance to convert to horizontal distance, a forester records a slope of 30% over 100 feet of slope distance. The horizontal distance is approximately:

Accepted Answer

95.4 feet

Answer

For a 30% slope (angle ≈ 16.7°), horizontal distance = slope distance × cos(16.7°) ≈ 100 × 0.954 = 95.4 feet.

Question 2

What is the standard diameter at breast height (DBH) measurement point in the United States?

Accepted Answer

4.5 feet above ground

Answer

In the US, DBH is measured at 4.5 feet (1.37 m) above the ground on the uphill side of the tree.

Question 3

In a two-phase (double) sampling design for forest inventory, Phase 1 typically involves:

Accepted Answer

Rapid, inexpensive measurements on a large sample to stratify the population

Answer

Phase 1 collects inexpensive auxiliary data (e.g., aerial photo interpretation) on many points used to stratify before the smaller, costlier Phase 2 ground sample.

Question 4

Which instrument is specifically designed to measure the diameter of standing trees at heights above ground without climbing?

Accepted Answer

Optical dendrometer

Answer

An optical dendrometer (such as the Wheeler pentaprism or Barr & Stroud) allows measurement of stem diameter at any height without climbing.

Question 5

A forester uses a Biltmore stick to estimate tree diameter. The stick works by holding it at a fixed arm's length distance and reading the scale. This method relies on the principle of:

Accepted Answer

Similar triangles using the eye as the apex

Answer

The Biltmore stick uses similar triangles: the stick at arm's length, the eye, and the tree diameter form proportional triangles, allowing diameter estimation.

(SAF) Society of American Foresters Certification Practice Test

(SAF) Society of American Foresters Certification Practice Test

SAF Field Survey & Data Collection 3