Pentaprism:Ī medium weight and cost instrument for measuring tree diameter. The user enters numbers read from a rifle-scope and a simple computer chip calculates diameter. The Criterion uses laser light to determine the distance from a tree. Criterion Laser:Ī heavy height, diameter and range measuring instrument. The Telereskop is similar in principle to the except that it includes 5 x optical magnification. Telerelaskop:Ī research quality instrument that is no longer in production. A sophisticated, compact and robust device for measuring range, tree height and diameter, and stand parameters. Spiegel Relaskop (Relascope):Ĭommonly referred to as a Relaskop. The most widely used type is the light, hardwearing, metal alloy caliper. There are a wide variety of calipers available. This limitation may restrict the use of calipers to smaller trees – the large diameter trees often found in natural eucalypt forests would require calipers arms in excess of 1 m which would be inconvenient. Biased estimates (underestimates) of the diameter will result if the arms are less than half the tree diameter. The length of the caliper arms must be at least half the diameter of the tree. The calipers must be located perpendicular to the stem axis. The moveable arm is then placed flush against the other side of the tree and the scale is read directly. The fixed arm is placed along one side of the tree at the desired height. Calipers:Ĭalipers are comprised of a fixed arm, scale, and moveable arm. Keeping the tape numbers right side up (as in the photograph) reduces the chances of incorrectly reading the scale – when upside down errors like x.4 being recorded as x.6 are common. The tape should also be wrapped around the bole in a perpendicular plane to the stem axis.
The tape should be held relatively firmly (but avoid stretching). Often the tape will have normal units (mm and cm) on one side and PI units on the other side. This value is divided by PI (3.1415….) to estimate diameter. The tape is wrapped around the tree to measure the circumference. Tools for Measuring Tree Diameter Fiberglass tape:Ī girth tape measures diameter indirectly. Parameters for Measurement of Tree Bole.Ranking tools for ease, effectiveness, and cost.
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