Friday, May 13, 2011

Logging the Log

Been holding this little bit of text for several days due to problems on the Blog site.  Didn't stop viewing - only creating.

I tend to over "record keep" my garden info.  Not that I consider it over-keeping although others may refer to it that way behind closed doors, in hushed tones and with a few "tisk tisks" thrown in for good measure.

Since I take pictures during different growing seasons, it became visually obvious many of my trees had finally settled in and were growing - a lot.  "Just how much is a "lot"?" I asked myself.  This sent me to the web for "how to measure the height of a tree" when it is taller than any sane person would want to climb.

The following information was on so many web sites, in exactly the same form, word for word, I'm not going to bother crediting it to one source.  It's not my creation and that's credit enough.

There are several ways to measure the height of a tree. 

"To measure a tree’s height, an Abney hand level, clinometer, or transit is recommended."  OK, I've no idea about these devices and sure they aren't in my garage tool drawer. 

This "Shadow" method sounds easy:
  • Stand next to the tree or the object to be measured. For best results, do this method on a bright, sunny day. If the sky is overcast, it may be difficult to tell exactly where the shadow’s tip is.
  • Measure the length of your shadow. Use a tape measure or yardstick (meter ruler) to measure your shadow from your feet to the tip of your shadow. If you don’t have someone to assist you, you can mark the end of the shadow by tossing a rock onto it while you’re standing. Or better yet, place the rock anywhere on the ground, and then position yourself so the tip of your shadow is at the rock; then measure from where you're standing to the rock.
  • Measure the length of the tree’s shadow. Use your measuring tape to determine the length of the tree’s shadow from the base of the tree to the tip of the shadow. This works best if the ground all along the shadow is fairly level; if the tree is on a slope, for example, your measurement won’t be very accurate. You want to do this as quickly as possible after measuring your shadow, since the sun’s position in the sky (and hence the shadow length) is slowly but constantly changing. If you have an assistant, you can hold one end of the measuring tape while he or she measures the tree’s shadow, and then you can immediately measure your shadow.
  • Calculate the tree’s height by using the proportion of your shadow’s length to your height. Since you know the length of the tree’s shadow, and you also know that a certain height (your height) produces a certain shadow length (the length of your shadow), you can determine the tree’s height with a little math. Multiply the length of the tree’s shadow by your height, and then divide the resulting number by the length of your shadow. For example, if you are 5 feet (1.5 meters) tall, your shadow is 8 feet (2.4 meters) long, and the tree’s shadow is 100 feet (30.48 meters) long, the height of the tree is (100 x 5) / 8 = 62.5 feet (30.48 x 1.5 meters) / 2.4 meters. Note that the order of your multiplication does not matter.

This is called the "yardstick" method: 
  • Using a yardstick, stand exactly 25 feet from the tree being measured. Hold the yardstick, with the zero end downward, 25 inches from your eye. Line up the bottom of the yardstick with the base of the tree. Without moving your head, look to the top of the tree. Where it crosses the yardstick, read off the measurement in inches. Each inch will equal one foot in the tree's height.
  •  If the tree is taller than your  yardstick will measure, stand 50 feet away. Again hold it 25 inches from your eye, as before, only this time multiply your result by 2 to get the correct height. If it is taller still, then step back to 75 feet, multiplying your result by 3, or 100 feet, multiplying the result by 4, etc.
So - there you have it - measure and record to your heart's content. 
This photo is of what was once a State of Illinois record setting Chestnut tree.  It's located on 400N in rural Galva IL.  It is no longer the record holder because it is damaged, but, still pretty amazing.  There's lists of record setting trees on the web.    


  1. The method I use is a 'survival' technique . Walk away from the tree ; stand with your feet about a foot and a half apart ; bend over and look between your legs ; keep increasing the distance from the tree until you can see the top of it between your legs. The distance from the tree to where you end up is the height of the tree. It works for me.

  2. Thanks "thepowmill", An interesting way to measure without additional things needed. Diane