Michigan datbases entries

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gjschmidt
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Michigan datbases entries

Post by gjschmidt » Fri Jun 17, 2016 8:29 am

I recently visited Fabius State Game Area in St. Joseph County. Though many of the game areas are fairly cut up and invaded by multiflora rose and garlic mustard, there are a few nice stands. One such stand includes a tuliptree that I initially measured at 39.0 m tall with my laser hypsometer. But eventually, after wandering around the game area, I came across the same tree from the other direction without realizing it at first; I got a reading of 40.2 m (131.9 ft or 43.97 yd). Under most circumstances, at least hypothetically, the instrument with it's "sine" method is more likely to underestimate (as opposed to traditional clinometer and ground tape "tangent" methods), so I recorded the higher number.

I entered this tree along with a decent sized red oak in the Trees Database:
https://treesdb.azurewebsites.net/Brows ... 64/Details

This is the tallest tree reported for Michigan thus far in the tree database. Though someone did have a spreadsheet which reports a slightly taller tuliptree in southeast Michigan, it has yet to be recorded here:
https://treesdb.azurewebsites.net/Brows ... 20/Details

My only issues with the database are that while I have "m" selected to display metric units, it treats everything as feet when I entered it. Also, I wish it would accept diameters, since this is what I had recorded using a dbh tape, and is what I visualize when looking at a tree. I suppose that others lack dbh tapes and visualize trees in terms of how many people it takes to hug a tree. I get that. I also understand that we actually measure circumference regardless of what the tape says, and that a elliptical tree would have a smaller basal area than implied by its circumference. But making the option of centimeters and diameter would make it easier for me to enter data.

For some reason, the Fabius State Game Area site doesn't show up on the map yet, even though it does have coordinates. Perhaps a delay?
Greg Schmidt

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Don
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Re: Michigan datbases entries

Post by Don » Sat Jun 18, 2016 3:50 pm

gj-
Wondering which laser hypsometer you're using?
I understand your interest in measuring in meters, and you're a good role model for us out there! With regard to your comment on d-tapes, I also share your views on diameters being what you 'see' and other reasons why it was a standard for so long. But the farther the tree gets from being perfectly conical, the more inaccurate diameter readings are; conversely, measuring the circumference is constant. And added advantage that most d-tapes have is that the back side of the tape has gradations that are in units of circumference. If you have this kind (and I recommend them), you can determine the circumference at home by thumbing the diameter reading, then flipping over the tape and reading the circumference direct...at least on the models I use, and am familiar with!
Don Bertolette - President/Moderator, WNTS BBS
Restoration Forester (Retired)
Science Center
Grand Canyon National Park

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View my Alaska Big Tree List Webpage at:
http://www.akbigtreelist.org

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ElijahW
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Re: Michigan datbases entries

Post by ElijahW » Sat Jun 18, 2016 6:53 pm

GJ,

Well done on the tuliptree measurement. Locating both top and bottom of the targeted tree in a forest environment can be difficult, especially with the leaves on.

In regard to the Trees database, it hasn't been utilized fully, and certain states, like Michigan, are lightly represented or not represented at all. Many measurements from NTS members exist from Michigan (see Doug's work at Hartwick Pines), but they haven't been entered into the database. Obviously, the more data the better, but everyone is free to do (or not do) what they wish. Issues with the database have been presented in the past, and while it does have flaws and infrequent glitches, it's also a great tool. I don't pay much attention to the map function, so I can't help you with that. I assume the conversion from metric to SAE units is enabled for smoother searchability. The database also converts inches and feet together to just inches.

On the sine vs. tangent method, you're right on about their relative accuracies. The limiting factors using the sine method include the accuracy of your instruments and your ability to see clearly both the top and bottom of the tree.

I agree with Don on the circumference vs. diameter question. Referencing a tree's diameter may seem more intuitive, but the circumference better represents its overall footprint.

Again, well done,

Elijah
"There is nothing in the world to equal the forest as nature made it. The finest formal forest, the most magnificent artificially grown woods, cannot compare with the grandeur of primeval woodland." Bob Marshall, Recreational Limitations to Silviculture in the Adirondacks

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gjschmidt
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Re: Michigan datbases entries

Post by gjschmidt » Wed Jun 29, 2016 10:17 pm

I have a Nikon Forestry PRO Laser Rangefinder/Hypsometer.
http://www.forestry-suppliers.com/produ ... mnum=91140


As far as girth goes, d-tapes measure circumference regardless of which side of the tape used. Diameter in this case is just a ratio of circumference. If the tree is a very flat ellipse in cross section, then yes, real diameter will vary from 0 to 0.5 the circumference, both larger and smaller than what the d-tape says. It might seem arbitrary then to prefer a set ratio to the direct circumference measure, but the same could be said of using other units of measurement.

But what is real diameter? Unless we had calipers to properly measure both axes, we cannot really get what the forester is really interested in, which is basal area. Circumference doesn't get us any closer to basal area than the diameter side of the d-tape. But I accept that limitation, since taking it really seriously would also require assessing buttressing and the additional curving in and out from the tape.
Greg Schmidt

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Don
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Re: Michigan datbases entries

Post by Don » Thu Jun 30, 2016 1:51 am

gj-
As a lifelong forester (GS-3 Forestry Aid, 1967), topographic abneys, measuring in chains, surveying with mountain transits...basal area prisms, and such. All foresters world stuff. I initially took your same stance on diameters. It's what I see, when I walk up to a tree. But just as two successive caliper readings may give you two different diameters on a tree that is 'out of round' (as most are), diameters don't have the incontrovertible state that circumferences do. Calipers don't measure circumference.

But this world, NTS (Native Tree Society) has taken on a mantle of more accurate measurement methodology than that used by USFS, BLM, state and county foresters.

As a forester, I was as good as any at classing diameters of trees in 2" classes, on the fly, and tree heights to a 4" commercial top. But that's about as accurate as we were expected to get. As foresters.

We also measure the circumference, not necessarily from the top side of the tree's base, but from it's mid-slope position, as that's a solid a relationship with the original location of the trees seed. Check it all out in the American Forests online Measuring Guidelines, at:
http://www.americanforests.org/wp-conte ... nes_LR.pdf
-Don
Don Bertolette - President/Moderator, WNTS BBS
Restoration Forester (Retired)
Science Center
Grand Canyon National Park

BJCP Apprentice Beer Judge

View my Alaska Big Tree List Webpage at:
http://www.akbigtreelist.org

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