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A volume table is a chart to aid in the estimation of standing timber volume. These tables are based on volume equations and use correlations between certain aspects of a tree to estimate the volume to a degree of certainty. The diameter at breast height (DBH) and the merchantable height are used to determine the total volume. Difficulties ...
Site index – a species specific measure of site productivity and management options, reported as the height of dominant and co-dominant trees in a stand at a base age such as 25, 50 and 100 years; Tree taper – the degree to which a tree's stem or bole decreases in diameter as a function of height above ground. So it can be sharp or gradual.
Electronic calipers can measure diameter at breast height and send measured data via Bluetooth to a field computer. Tree trunks are measured at the height of an adult's breast, which is defined differently in different countries and situations. In many countries, DBH is measured at approximately 1.3 m (4.3 ft) above ground. [1] [2]
[2] [4] Elsewhere in the world it is measured at a height of 1.3 meters, [19] 1.4 meters, [5] [20] or 1.5 meters. [21] Tree girth measurement is commonly performed by wrapping a tape around the trunk at the correct height.
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. The left side of the stick is flush with the left side of the tree.
However, as the tree is heavily buttressed, and irregular in shape, a calculation of nominal diameter, defined as the cross-sectional wood area expressed as a circle, gives this tree a diameter at breast height of 30.8 feet (9.4 m)—a much smaller number, but a more accurate representation of the tree's size. [10]
This height is noted and the diameter of the tree is measured at that point. The climber then rappels down the tree measuring the trunk circumference by tape wrap at different heights with the height of each measurement referenced to the fixed tape running down the trunk. [citation needed] Direct trunk measurements are obtained by a tree climber.
Where N = number of trees per acre D = dbh of the tree of average basal area k = a constant varying with the species When the quadratic mean diameter equals 10 inches (250 mm), the log of N equals the log of the stand density index. In equation form: log 10 SDI = -1.605(1) + k Which means that: k = log 10 SDI + 1.605