I don't get to see American Elm in good shape out in the woods too often. I found this one a couple years back and its time came for a closer look up in the crown. This is a species I'd never climbed, always a treat to explore a new tree personality. Good news is my hand throwing is back to 100% after working through shoulder problems in the first part of '11. Once the temps get below 40f the slingshot is pretty much useless for high throws.

Cool weather finally arrived, elm likes wet habitat


Ropes in let's climb


Bark like feathers


Hanging up top with my friend Paul


-AJ

Nice climb Moss.

Any estimate on height for the Elm?

Not super tall, upper 80's maybe lower 90's. My eye for height estimation can be way off, I'm returning later this week to measure it and several other trees near it with a clinometer and laser rangefinder. I'll report back.
-AJ

Great pictures. I don't think I've ever seen an Elm tree to be honest. That is a super great idea to use a laser range finder I have one and never thought about using it to measure height

Dan

Not my original idea The technique is used by the west coast/PNW tall tree explorers as well as the east coast folks who are dedicated tree measurers.

Technique goes something like this, it's called the "Sine top/sine bottom" method:

1. Stand back from the tree and find a position where you can see the very top of the tree and the base of the trunk. This is challenging in forest conditions, takes some work to find the best place to measure from.
2. With the rangefinder locate the topmost twig of the tree, record the distance (yards or meters)
3. Without moving from where you are standing use a clinometer pointed at the topmost twig to determine the angle, record the angle
4. Assuming the height of your head is higher than the base of the tree point the rangefinder at the base of the tree where it meets the ground and record the distance
5. Point the clinometer at the same location base of the tree and record the angle

Ok now you have the data you need to determine the height. This will be the actual true vertical height of the very top of the tree, not the the length of the trunk. This technique is very effective for any amount of lean or offset of the top over the base. Actually, no tree is perfectly straight, there's always some offset.

Calculate height from data (you'll need a calculator that will do sine functions)

Sine top value
1. Perform a sine function on the angle to the top
2. Multiply the results by the distance to the top
3. Multiply the results by 3 to convert yards from feet
4. You now have the height of the tree from your eye level to the top of the tree, record this value

Sine bottom value
1. Perform a sine function on the angle to the base of the trunk
2. Multiply the results by the distance to the base of the trunk
3. Multiply the results by 3 to convert yards from feet
4. You now have the height of the tree from your eye level to the base of the trunk, record this value

Total height value
Add the sine top value to the sine bottom value, you now have the total height of the tree.

This may seem very complicated but is actually very quick and relatively simple with a little practice. For example with practice values can be entered into the formula on the fly, no writing needed until you arrive at the total height.

Here's a sketch from my field notebook showing the technique and formula


Accuracy is often within a half inch of a manual tape drop measurement. Accuracy is only as good as the data you record, it can be difficult to find the actual top of a broad crowned hardwood, the measurer often has to make several measurements from different locations around the tree to find the true tallest point of the tree. Same is true for extremely tall conifers, it can be very difficult to actually see the very topmost twig.

Very expensive rangefinders can do all of the calculations for you, but that's $3,000 or more for that type of device. Nikon 440 or 550 rangefinders have excellent accuracy (what I use) and are relatively inexpensive for what you an do with them. There are many other brands of inexpensive rangefinders, the consensus of the experts is the Nikon 440 or 550 are far above the best of class for tree measuring.

What I've described is basic technique, there are many other considerations in tree measuring from the ground, more info here from the Eastern Native Tree Society
-AJ

Worth mentioning you can do a straight up shot to estimate the height of the tree. You will find though that it's very difficult to do that, at least to get an accurate value. Trees don't cooperate, too may branches in the way and for conifers no way.
-AJ

Great report, AJ. Thanks for the info on the sine measurement protocol. I like the closeup shot of the elm bark - really does look like a collection of feathers.

I tried one of these last week at a trade show. It has screen that you can zoom in on the object and not have to worry about finding the red dot. It calculates all the angles.

http://www.stabila.com/main.taf?p=1,2,3,9

That looks cool. For tree measuring you want to be looking through an optical lens at your target twig, otherwise it's way too easy to get lost visually when you're trying sight the highest twigs in woods conditions. So most laser devices that work well for the job have that feature.

This Nikon Forestry 550 has an optical sight with built-in clinometer and is excellent for the job. The user holds down the "on" button and scans the top to find the highest point, there's a height readout in the viewfinder so you can quickly zero on the tallest point.

I use the discontinued Nikon Prostaff 440 and a manual clinometer for the angles. The Nikon engineers accidentally (at least they had no idea the device would be adopted and loved by tree measurers) made the 440 extremely accurate with the ability to reach through many obstructing twigs with a precise narrow beam. A measurer can get a distance reading off a pencil thick twig on the top of the tallest tree you want to measure. It's still the favorite of tree measurers who don't jump up the $2-3k+ class of rangefinders. It's possible to get an excellent deal on a 440, a lot of tree measuring power for relatively little money.
-AJ

To get perspective on laser devices for tree measuring check out Michael Taylor's recent post on the subject in the ENTS forum. Michael is probably one of the most demanding and dedicated tall tree measurers on the planet. Michael discovered Hyperion (coast redwood), the current tallest measured living tree.
-AJ

Good references, thanks. Except Nikon doesn't offer enough choices on that link!

I have no idea if the Stabila unit would work on trees. I was looking at it to use for building/remodeling, but of course my first thought was wondering if it would work for a tree. For a single tree out in the open, probably pretty easy. To use in a thick forest is probably much easier said than done.