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Part 2 - Height Slide 2 - an instrument for measuring heights (of trees) Slide 3 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) Slide 4 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 Slide 5 Trigonometry of right triangles a = b(tan A) Slide 6 Slide 7 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 Slide 8 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 Slide 9 Slide 10 Slide 11 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 Slide 12 Measuring Tools Slide 13 Slide 14 Slide 15 Slide 16 Line of site limitations, expensive Slide 17 Slide 18 Slide 19 Slide 20 Slide 21 Degree and Topographic Scales Slide 22 Degree and Percent Scale Slide 23 Slide 24 Slide 25 Slide 26 Left scale in percent at 100 feet. What is the tree height? Slide 27 Compensates for angle Slide 28 Not Limited by Line of Sight like Laser or Optical Slide 29 Slide 30 Slide 31 Show General Formula Slide Show iTunesU video Show iHypsometer App Questions so far? Slide 32 Problem Trees Slide 33 Measure perpendicular to the lean, angling your hypsometer (reads normally) Slide 34 Can use Pythagorean Theorem to solve Slide 35 You measure B normally (not full tree height) To get true bole length (A), you need angle C also Then A = B/cos C Slide 36 Slide 37 Slide 38 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 Slide 39