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Re: Largest elm in NY

Posted: Wed Oct 09, 2013 4:06 am
by morgan
Distance to top same as distance to base.

Re: Largest elm in NY

Posted: Wed Oct 09, 2013 5:05 am
by Will Blozan
Morgan,

Ok, so you were 49.5 feet above the base? Or was the top leaning towards you proportionally so that 300 feet away you had an equilateral triangle? I am still not sure how you measured distance to top without a rangefinder other than cross-triangulation which would be a separate triangle than for the base.

Sorry, I am just trying to understand the premises here...

Will

Re: Largest elm in NY

Posted: Wed Oct 23, 2013 2:06 pm
by morgan
I was the same distance from the base as I was from the point on the ground directly under the top.

Re: Largest elm in NY

Posted: Wed Oct 23, 2013 2:14 pm
by morgan
As for the pic I posted on Oct 7, that is not going to work. When I got a better look, that top is not really higher it's just closer. The highest point on the tree is not visible from anywhere on the ground, because of the umbrella shape to the crown. I eventually gave up looking for the top and just stood right near the base and shot the Nikon 440 vertically a few dozen times, maybe 100 times, until I was convinced that 28.0 yards was the highest. I got 27.5 a bunch of times and 28 a bunch of times and I missed a bunch of times, but never got 28.5 so I was satisfied.

28 yards is 84 feet, and I'm 6 foot 4 and when I tip my head back like that my eye height is 6 foot 6 which adds up to 90.5 feet. The sidewalk is about .5 feet below the base so the tree is 90 feet tall.

That's my final answer. 90 feet.

Re: Largest elm in NY

Posted: Wed Oct 23, 2013 4:30 pm
by Will Blozan
Morgan,

Thanks for the update. Sometimes shooting straight up is the best- or most accurate way- when the ground is flat. Elms are notoriously difficult!

Will

Re: Largest elm in NY

Posted: Wed Oct 23, 2013 6:58 pm
by morgan
You got that right. Every time I tried to shoot the top with the Nikon, with the sine method or the cosine method, the top was closer than the base!!!!!!

Shooting straight up was the only way.

Re: Largest elm in NY

Posted: Wed Oct 23, 2013 7:41 pm
by dbhguru
Morgan,

Good explanation and thanks for your perseverance. I now wonder if the Old Deerfield, MA elm might not be a few feet higher because of its top being well inside its wide crown and not visible from where I commonly shoot the tree. Shooting straight up from beneath the tree when the leaves are off is a technique not to be discredited. Very useful. Bart Bouricius is especially good at finding the top of a broad-crowned hardwood this way. Any way, sounds like you've got that tree nailed.

Bob

Re: Largest elm in NY

Posted: Wed Oct 23, 2013 8:04 pm
by tsharp
Morgan: I am still a little confused about your troubles with the Elm. When you say the top was closer than the base do you mean to you. ie.(the observer with a range finder)?
TS

Re: Largest elm in NY

Posted: Thu Oct 24, 2013 6:23 am
by Will Blozan
Morgan,

Yeah, it is entirely possible the highest point could be well out from the "base" on a lateral branch. This was the case on a huge cedar of Lebanon in VA I measured in 2006. The highest point after tons of searching was way out almost at the edge of the crown spread. Other parts "looked" taller but the laser does not lie.

Measuring a tree is simply defining the vertical distance between two points. There is no- and never has been- any relationship between the two points with regard to how they are measured. Forget the tree- it is not the slightest factor whatsoever in the measurement protocol. If you find yourself wondering why the top is so far off the base you are no longer on task.

Will

Re: Largest elm in NY

Posted: Thu Oct 24, 2013 7:13 am
by dbhguru
Will,

This lesson is a very hard one for people to accept, especially those who work with trees, if their focus is the trunk. We're battling decades of habit. How many clinometers are out there with manufacturer diagrams that show a level baseline to the trunk in their height diagrams? It seems so natural to set the baseline from eye to trunk - unfortunately.

Bob