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Published byTaryn Giberson Modified over 2 years ago

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Part 2 - Height

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- an instrument for measuring heights (of trees)

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Total height = height (or stem length) from ground line to top of terminal bud. Merchantable height = stem length (or height) from assumed stump height to an arbitrary, fixed upper-stem diameter (ib or ob)

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Degree – reads angle from horizontal for trigonometric calculations Percentage – reads directly in feet of height at 100 feet distance (rise/run) (45 degrees equals 100 percent slope) Topographic – reads directly in feet of height at 66 feet (1 chain or 20 meters) away This is where your pacing or hipchain really comes in handy

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Trigonometry of right triangles a = b(tan A)

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Measuring Standing Tree Height Percentage Scale Percent slope = (rise / run) x 100 If distance from tree (D), or "run" is 100 feet, The reading from horizontal to Stump height (A) is 5 feet and tree height above the horizontal plane (B) or "rise" is 80 feet Total Tree height equals A + B = 85 feet

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H = (HT - HB)*(HD/BD) HT = Height to top (BA) HB = Height to Base (BC) Reading will be negative (unless tree above you) HD = Horizontal Distance From person to tree BD = Base Distance 66 (for topographic scale) Or 100 (for percent scale) If you are at scale distance, This factor (HD/BD) equals 1 and can be ignored

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Desired horizontal distance to the tree = 100 feet Slope to the tree = 32% (slope correction needed) Slope correction factor = 1.05 Taped distance to the tree = 100 feet * 1.05 = 105 feet The measuring instrument is moved to a taped distance of 105 feet Angle to tree base = 4%; Angle to tree top = 76% Tree height = 76 feet - 4 feet = 72 feet

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Measuring Tools

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Line of site limitations, expensive

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Degree and Topographic Scales

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Degree and Percent Scale

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Left scale in percent at 100 feet. What is the tree height?

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Compensates for angle

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Not Limited by Line of Sight like Laser or Optical

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Show General Formula Slide Show iTunesU video Show iHypsometer App Questions so far?

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Problem Trees

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Measure perpendicular to the lean, angling your hypsometer (reads normally)

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Can use Pythagorean Theorem to solve

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You measure B normally (not full tree height) To get true bole length (A), you need angle C also Then A = B/cos C

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Measure height of the stub Measure length of the piece on the ground (trigonometry may be needed) Add the two measurements to obtain total height

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