ICAR AICE-JRF/SRF Forest Mensuration: practice questions

1 · Diameter and girth measurement: breast height conventions, calipers, tapes · hard

A stem cross-section at breast height is clearly elliptical. Compared with the diameter of a circle of equal area, the diameter obtained from a girth tape (girth ÷ π) is:

1. Slightly smaller, because the tape takes the short axis of the ellipse
2. Exactly equal, because girth always reflects area for any closed shape
3. Slightly larger, since an ellipse has a longer perimeter than an equal-area circle
4. Exactly equal, because girth reflects cross-sectional area for any closed stem shape

2 · Bark thickness and crown measurements · medium

Why is bark percentage of volume taken from local measurements rather than a single standard value?

1. Bark thickness is fixed for each species, but standards change with timber prices
2. Bark is always close to one-tenth of volume, but tables round it differently
3. Bark thickness varies with species, age, tree size, height on the stem and site
4. Bark is excluded from all volume tables, so no value is ever needed

3 · Log volume formulas: Huber, Smalian, Newton · hard

Which log is most overestimated by Smalian's formula?

1. A flared butt log resembling a neiloid frustum
2. A mid-stem log resembling a paraboloid frustum
3. A perfectly cylindrical log of uniform diameter
4. A short log cut from the middle of a cylindrical bole

4 · Volume of standing trees: form factor and form quotient · hard

The absolute form factor differs from the breast-height (artificial) form factor in that it:

1. Uses the diameter at one-tenth of total height as the reference section
2. Uses under-bark volume and the over-bark basal area of the stump
3. Uses only the volume and height above breast height, with breast-height basal area
4. Uses the merchantable height instead of total height and includes the stump

5 · Volume of standing trees: form factor and form quotient · hard

Why must a form factor be used with the same definitions under which it was derived?

1. Its value depends on the reference diameter, the height and the volume definition used
2. Its value is fixed for each species, but the units used for volume differ between countries
3. Form factors apply only to conifers, so broadleaf definitions differ
4. Its value is fixed by the solid of revolution the species resembles

6 · Tree biomass and allometric equations · medium

Allometric biomass equations are usually built by:

1. Measuring dbh only and applying the carbon fraction to stem volume
2. Weighing standing trees with load cells attached to the main roots
3. Felling trees, weighing parts fresh and oven-drying subsamples for dry mass
4. Counting rings on increment cores and multiplying by wood density

7 · Tree biomass and allometric equations · hard

In a forest carbon estimate built from inventory data, which choice is often the single largest source of error?

1. The choice of allometric equation that turns measurements into biomass
2. The rounding of dbh to the nearest centimetre by the field crews
3. The use of the ratio 44/12 to convert carbon to carbon dioxide
4. The number of decimal places kept in the basal area factor

8 · Angle-count (Bitterlich) sampling and relascopes · hard

On steep ground, an uncorrected angle count made with a simple fixed-angle gauge will:

1. Overestimate basal area, because more trees appear wider on slopes
2. Give the correct basal area, because the angle does not depend on slope
3. Give the correct basal area only for trees uphill of the point
4. Underestimate basal area, since the effective horizontal angle is too small

9 · Age determination and stem analysis · medium

In stem analysis of a 30-year-old tree, the disc cut at 3.3 m has 24 rings. At approximately what age did the tree reach 3.3 m?

1. 24 years
2. 4 years
3. 6 years
4. 26 years