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Therefore, the vertical distance to the base of the tree above or below eye level is [h2 = sin(b) x D2]. Common sense should prevail when adding h1 and h2. If the base of the tree is below eye level the distance it extends below eye level is added to the height of the tree above eye level to calculate the total height of the tree.
horizontal distance at eye level to the tree trunk x tangent Θ = height above eye level If the tree extends below eye level the same process is used to determine the length below eye level and that is added to height above eye level to determine total tree height. Different clinometers have different reading scales, but all apply the same ...
A Biltmore scale inscribed on an axe. Diameter at breast height (DBH) is measured by holding the stick a fixed distance, usually 25 inches (64 cm), from the eye, and at breast height, which in the United States is 4.5 feet (1.4 m) up the bole of the tree.
In 1914 and 1915, the Forestry Quarterly published a series of articles on the use of the Abney level. [6] [7] [8] These tutorial articles remain useful today, but the primary reference for usage is the 1927 Abney Level Handbook. [3] The Abney level is typically used at the eye height of the surveyor, either hand-held or mounted on a staff at ...
An angle gauge is a tool used by foresters to determine which trees to measure when using a variable radius plot design in forest inventory. Using this tool a forester can quickly measure the trees that are in or out of the plot. An angle gauge is similar to a wedge prism though it must be held a fixed distance from the eye to work properly ...
When stocking, a tree's basal area is measured. The basal area is a cross-sectional area of the stump taken about 4.5 feet (1.4 m) above the ground. [7] The equation for calculating the basal area of trees in a stand is Basal Area = 0.005454 DBH 2, where DBH is the diameter of the tree at the aforementioned measuring height. [7]
Calculation from this value will eventually give the height h, from the eye-line of the observer to the top of the object whose height is to be determined. Similarly as in step 2 of the illustration, a sighting is taken on the base of the object whose height is to be determined, and the reading on the horizontal scale, d', recorded.
The girth measurement should then be taken at the narrowest point below the odd growth and the height of the girth measurement noted. In some cases a girth taken just above the odd growth will be more representative of the actual girth of the tree. In these cases the measurement should be taken there and the height above the base of the tree noted.