Report

Part 2 - Height - an instrument for measuring heights (of trees) 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) 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 Trigonometry of right triangles a = b(tan A) 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 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 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 Measuring Tools Line of site limitations, expensive Degree and Topographic Scales Degree and Percent Scale Left scale in percent at 100 feet. What is the tree height? Compensates for angle Not Limited by Line of Sight like Laser or Optical Problem Trees Measure perpendicular to the lean, angling your hypsometer (reads normally) Can use Pythagorean Theorem to solve • You measure B normally (not full tree height) • To get true bole length (A), you need angle C also • Then A = B/cos C 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