Tree Measurements - Some stray thoughts   Robert Leverett   May 30, 2007 12:10 PDT  ENTS,     A few more thoughts on ENTS adopting the new measure for big trees that I just proposed. Firstly, our standard measures of full tree height and CBH are fine for the vast majority of trees that we measure. Adding maximum and/or average crown spread adds significantly to the numeric description of a tree, especially if teh crown spread is great. But, trees that are unremarkable, such as a 100-foot, narrow-crowned, forest-grown oak just don't warrant taking slew of extra measures unless we're doing scientific research that calls for added measures. However, the real giants across the landscape deserve more more kinds of measures. In particular, the CPA(n) concept makes sense for the live oaks that Larry Tucei Jr. measures because the huge ground area they cover and the proximity of the limbs to the ground, i.e. the composite limb architecture of the live oak is the hallmark of the species. I would propose for the big spreading trees the following measures.     1. Full tree height (H)     2. Height to major point of branching (Hb)     3. Girth at breast height (GBH)     4. Girth at ground level (GGL)     5. Maximum spread (MS)     6. Average spread (AS)     7. Concave polygon area crown cover CPA(n)     Beyond these measures, there is trunk and/or limb volume, but that involves a mountain of work. So, the trees we volume model will usually be for specific research purposes. The Middleton Oak demonstrated the extreme effort required to volume model a big live oak.     We might establish thresholds for using the above 7 measures, e.g. all trees over 20 feet around would get the full treatment. Just a thought. Ed, what are your thoughts? Bob Robert T. Leverett Cofounder, Eastern Native Tree Society Re: Some stray thoughts   Edward Frank   Jun 03, 2007 07:52 PDT  Bob, Your list seems fine. I will leave the crown area and crown volume to a separate thread, but want to review the basic concepts presented by your first 6 measurements on the list. A fuller treatment is given in the Tree Measuring Guidelines of the Eastern Native Tree Society document. Bob Leverett wrote: "Firstly, our standard measures of full tree height and GBH are fine for the vast majority of trees that we measure. Adding maximum and/or average crown spread adds significantly to the numeric description of a tree, especially if the crown spread is great. But, trees that are unremarkable, such as a 100-foot, narrow-crowned, forest-grown oak just don't warrant taking slew of extra measures unless we're doing scientific research that calls for added measures. However, the real giants across the landscape deserve more kinds of measures..    We might establish thresholds for using the above 7 measures, e.g. all trees over 20 feet around would get the full treatment. " 1. Full tree height (H):   This is the most critical measurement for many of our research efforts. Measurements made using the distance from the base of the tree and the angle to the top are just not acceptable. The mechanics of using a laser rangefinder and a clinometer are pretty straight forward. First find a spot where you have a good view of the tree. Four measurements need to be taken. a) Using the rangefinder find the highest point on the tree. For a number of branches at a similar angle, the branch that is farthest away is the highest branch. Write down the distance measured by the rangefinder to the top of the tree. This distance is most accurate when it is at the point where the distance number changes upward from one number to the next higher number. b) Measure the angle to the same top point with the clinometer and write that number down. c) Measure the distance to the base of the tree using the rangefinder from the same point that the top was measured, and write that number down, d) Measure the angle to the base of the tree using the clinometer and write that number down, noting whether the base of the tree is above or below the point from which it s being measured. e) Use a pocket calculator to determine tree height. Here is an example: After the four measurements that have been taken., and say the angel gle to the tree top = 47 , distance to the top = 35 yards, angle to the base = -7, and distance to base = 23 yards: 1)First punch in the top angle [47], 2) press the sin button on the calculator [In this case the number that appears will be 0.73135], 3] press the multiplication key [X], 4) type in the distance to the top in yards [35], 5) press the multiplication key [X], 6) type in the number 3 [3 feet per yard], 7) press the = sign. This will give you the height of the top above your eye-level. [76.8] 8) Write this number down, it is the height of the tree top above eye level. Next calculate the "height" of the base of the tree, using the same steps. 9) First punch in the base angle [7], Ignore at this step whether the number is positive or negative. 10) press the sin button on the calculator [In this case the number that appears will be 0.1219], 11] press the multiplication key [X], 12) type in the distance to the top in yards [23], 13) press the multiplication key [X], 14) type in the number 3 [3 feet per yard], this gives you 69 feet 15) press the = sign. This will give you the height of the top above your eye-level. [8.4] 16) Write this number down, it is the height of the base of the tree above or below eye level. In almost every case the top of the tree will be above eye level, so it will be a positive number. 17) If the base of the tree is below eye level [negative angle], add the two numbers [from steps 8 and 16] together to get the height of the tree. 18) If the base of the tree is above eye level, subtract the base height [step 16] from the top height [step 8] to obtain the height of the tree. 2. Height to major point of branching (Hb): This is measurement that is not regularly obtained. Find the lowest point on the trunk where the major branching begins (ignoring epicormic sprouts, and so forth) Using the same methodology as described above for tree height, measure the height of this point above the base of the tree. 3. Girth at breast height (GBH): Girth is a dimension taken at a point 4.5 feet above average soil level. If a burl or other atypical growth formation is encountered at this point the least distorted girth below this point is used; or just above breast height as appropriate.. When a tree is growing on a slope the girth is taken at a point that is the average of the highest point and the lowest point the tree trunk appears to contact the soil (Mid- slope). This mid-slope rule is used to follow the American Forests guidelines for measuring champion trees. In all cases the girth is taken perpendicular to the axis of the trunk at BH, not parallel to the soil. 4. Girth at ground level (GGL): Again this is not a standard measurement. The base of the tree will flare outward and have many hollows and ridges leading to the underlying root structures.   In this case the girth would be measured from ridge to ridge around the periphery of the trunk. To do proper volume measurements a footprint map of all the hollows and ridged would need to be made, but this detail is not necessary for GGL 5. Maximum crown spread (CSM): This is the maximum horizontal distance from branch tip to branch tip through the central mass of the crown. It is generally measured by finding the a point directly underneath each of these points on the ground and then measuring the horizontal distance between these two points. 6. Average crown spread (CSA): This is the numerical average of the maximum crown spread as described above and the shortest spread measured at right angles to the CSM through the central mass of the tree crown. Edward Frank   Home