Georgia 4-H Forestry Field Day Manual The University of Georgia, Extension Forest Resources, Bulletin FOR96-029, 1996, 52 pp. Contest Events:
Participants will estimate the sawtimber volume in up to five (5) designated trees to an Contestants may use an official cruise or scale stick with no modifications. Diameter tapes, calipers, and other instruments
Contest Rules: - Merchantable heights will be determined to the
**nearest full half-log**for sawtimber. A half-log is defined as being 8 feet long. The minimum basal log will be 10 inches D.B.H., one log merchantable length, and have a minimum top diameter of 8 inches. See the following section on tree measures for details.
- Contestants must determine diameter and associated volume to the nearest one inch class.
- Record sawlog volumes as found in the standard International 1/4 (rule) tree scale volume table (Form class 78) provided by the contest judge (see page 13).
**Do not use the volume table found on the tree scale stick.**
- Contestants must be able to compute volumes on a
**per acre**basis from 1/10, 1/5, or 1/4 acre sample plots. Foresters seldom measure every tree when estimating volumes per acre. The concept of an expansion factor should be emphasized during contestant training.
Practice Preparation: Select and number five to ten sawtimber sized trees (10 inches DBH and larger). If possible, measure diameters with a diameter tape and merchantable height with an altimeter or clinometer. Careful "stick" measurements are acceptable. Avoid borderline trees, that is, those trees with a diameter or height that might easily be thrown one inch larger or smaller or one-half log higher or shorter. Give each contestant a scale stick and a sheet numbered with spaces for DBH, height, and volume. The following example may be used. Sawtimber Volume Estimation Sample Plot
For each tree, diameter breast height (DBH) and merchantable height in 16 foot logs (to the full half log) is measured and entered on the table. Then board foot volume for each tree is determined using the Sawtimber Volume Estimation Form
Measurement of Standing Trees:
DO NOT MOVE HEAD, JUST EYE.
Use the flat side of the stick, indicated "Diameter of Tree (in inches)." Hold the stick level at 25 inches from the eye, against the tree, at a height of 4-1/2 feet above ground perpendicular to the line of sight. Practice is needed to find both the 4 ½ foot point in relation to your height, and the 25-inch distance to your eye. When the stick is placed against a tree, close one eye, sight at the left or zero end. The stick and the tree bark should be in the same line of sight. Now - Height is measured as follows, pace out 66 feet from the base of the tree to a point where the entire tree can be seen. Hold the stick up right so that the "Number of 16 foot logs" side faces you. The zero end should point toward the ground. Plumb the stick at 25 inches from the eye. Sight the zero end to appear to rest at a one (1) foot stump height.
Merchantable tree cut height for Merchantable tree height for Read sawlogs to the full one-half log. Do not make a log longer than it actually is. For example, record a 2 3/4 log tree as 2 ½, not as a 3 log tree. Do not add length that is not present. Practice on pacing is needed to find the 66 foot point. The 25 inch distance from eye to stick is the same as in measuring tree diameter. Volume Tables These are a composite of actual volumes on an average basis. Once the tree measurement is determined, enter the appropriate table from the left with the tree diameter (D.B.H.). Move across to the right to the column containing tree merchantable height at the top. At the intersection of these two points will be that tree's volume. Read and record each tree volume directly and separately. For contest purposes do not use the volume table on the tree scale stick. Tree Volume in Board Feet (International ΒΌ)
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