New Eel River LiDAR reveals more 350' class redwoods

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M.W.Taylor
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New Eel River LiDAR reveals more 350' class redwoods

Post by M.W.Taylor » Sat Oct 13, 2018 4:02 pm

I recently processed some newer LiDAR for Humboldt Redwoods State Park and found a few more tall redwoods not yet known or measured. Last weekend I went there with friend John Montague to measure them. Interestingly, one of the 350'+ LiDAR hits was growing over a slope and inflated but nearby was an unknown smaller redwood with an amazingly pointy top. We measured the trees with a tripod mounted Impulse200LR and prism pole survey with remote trigger for the laser to keep it steady. Pressing the button on the tripod mounted Impulse200LR will move the laser up to 1/2 degree at least during the measurement so it is essential to have a remote trigger for best accuracy. The Trupulse200X can't be triggered with the cable but it can be triggered remotely through its blue-tooth connection using a free App from LTI for your Android or I-phone. I highly recommend using the remote trigger to utilize these forestry lasers to their maximum potential.

Survey Results:

Tree#1
Name: Steed
Location: Humboldt Redwoods State Park
Dbh: 13.7'
Height: 350.1'

Tree#2
Name: Waldo
Location: Humboldt Redwoods State Park
Dbh: 8.2'
Height: 351.8'

Tree#3
Name: No name
Dbh: About 12'
Height: About 343'

I attached a few pictures of these trees and the survey process with John.

As these redwoods grow you will likely hear about more tall ones being found in the future. I estimate Waldo to be adding at least 1 foot per year in growth. I arrived at this estimate using 2006 and 2011 LiDAR data for the area. This tree is clearly growing VERY fast.
Attachments
John and Steed
John and Steed
horse head shaped burl of Steed
horse head shaped burl of Steed
steed head.jpg (26.05 KiB) Viewed 2718 times
Waldo has a rocket top. Growing at least 1 foot per year over the last decade.
Waldo has a rocket top. Growing at least 1 foot per year over the last decade.
John under Waldo, one of the smallest known 350' class redwoods
John under Waldo, one of the smallest known 350' class redwoods
John measuring to Prism pole on low side of Waldo
John measuring to Prism pole on low side of Waldo
Last edited by M.W.Taylor on Tue Oct 16, 2018 10:47 am, edited 1 time in total.

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Bart Bouricius
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by Bart Bouricius » Sun Oct 14, 2018 10:17 am

Michael,

You keep coming up with incredible trees. Waldo is certainly a needle of a tall tree. It reminds me of a "Probado Tree" Pterygota excelsaI found in Carara National Park Costa Rica several years ago at 4.14' diameter it was 207' tall. It's still healthy and just over 210' with a straight up shot, but not the tallest in the Park. I should probably try a sign measurement from a ways back to get some precision now. I suspect some of the Eucalyptus trees may out-needle these trees though.

MarkGraham
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by MarkGraham » Sun Oct 14, 2018 2:24 pm

Nice variety in the new 350 foot class trees, and good enthusiasm in those trunk photos. There must be some grow in for new 350 foot trees in Humboldt, maybe two or three per year?

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Erik Danielsen
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by Erik Danielsen » Mon Oct 15, 2018 9:15 am

Hard to conceptualize that little base putting up 350' of wood! I read through "The Wild Trees" this past weekend and it's certainly been enriching my imagination when reading about or viewing photos from redwood explorations here on the boards.

A question about methodology- where can I read about how a prism pole survey is done and what it's purpose is in the measuring process? Are you using it to perform external baseline measurements, or is the role something else?

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M.W.Taylor
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by M.W.Taylor » Mon Oct 15, 2018 3:46 pm

Erik, I am using the leapfrog method with the prism and pole to survey to the base of the redwood through all the clutter. With these tall redwoods you need to get way back on the tree to see the top (500 feet or more is ideal). So you never get a good view of the top or the base together. The way it works is you get a great view of the top with laser on a tripod and using a remote trigger for best accuracy. Obtain the vertical height of the laser center (technically to the center of the pivot point of the mounting hardware) below the tree top from this far away view and record that number in an smart phone or notebook. Once getting this top shot you put the laser in filter mode so that it only can get distances from a prism or reflector. You can usually go right through foliage if not too dense. The idea here is to shoot to the prism after the initial top shot. The prism only allows a return when shooting straight into its center. Record that vertical offset from laser to prism and pick up the laser/tripod and move towards the tree to a spot in-between or sideways....whatever gives you a good clear path to the tree. At this point, the height of the tree is registered to the prism center so you can move the tripod around (make sure the prism and pole do not get moved). Set up the laser on tripod and shoot back to the prism pole and record that new offset. At this point, the height of the tree is registered to the laser center so you can now pick up the prism pole and move it to a new location closer to the tree (be sure to not move the laser on tripod at this point). Relocate prism and pole and then shoot the laser height offset to the prism again. At this point, the height of the tree is registered back to the prism center so you can pick up the laser and tripod and move closer to the tree base.....the point here is the survey benchmark goes back and forth from prism/pole to laser centroid. At some point you arrive at the tree base with the laser being the new benchmark after a "prism/pole back to shot". From here you set up the prism and pole again on low or high side with the point of the pole touching the ground around the base of the tree (we never go more than one trunk diameter away from the tree for ground level as a rule). You take one shot to high side and one shot to low side ground level of the prism around the tree base with prism pole point just touching the ground. (during the other prism/pole shots you do not need the pole point to touch the ground as those shots are just temporary benchmarks to keep track of the vertical offsets of tree top to prism and laser center...only need to rotate the prism on its pivot to point it towards the laser for the back-to shots.) Once you get the vertical offset to the prism on high and low sides you average the two offsets and add the height of the pole to the the summation of all the to and back shots from the tree top, to laser, to the prism, to laser, to prism, to laser. to prism on high and low side as the final survey. I will make a graphical illustration at some point if this is not clear. The method has been nicknamed the leapfrog method by Steve Colburn of Laser Technology when I met up with him in Oregon to measure a tall sugar pine there. I am sure there is a proper name for it in classical survey techniques.

I use a mini prism which can be bought on ebay for about $30 to $40. They have a 5/8-11 thread and bubble level for mounting on to a prism pole. The prism pole tripod is also needed. I use the Seco quick thumb release tripod for the pole to level it quckly and lock it down with a thumbscrew if I need to rasise the prism up high to see it though the brush and clutter. Sometimes you need to raise the prism up to 8' or even 12' if you have a double telescoping prism pole. You can also get a mini 3D prism with 1/2" pole for about $99 on ebay. See attached links for some of the equipment I use.

This is the only way to accurately measure a redwood without climbing it as far as I can tell.

https://www.ebay.com/itm/NEW-ALL-METAL- ... Sw6rxba~5C

I used to have 5 of these. You can pick them up at Ellis Engineering for about $150 each. Ebay seems to be the best deal.
https://www.ebay.com/itm/SECO-Thumb-Rel ... SwRvJZ5RVZ


Here is a pole and tripod for $179 as a combo package:
https://www.ebay.com/itm/New-8ft-2-6m-P ... Swxp9W8WZ0

cheapo pole and tripod here: I need a longer pole with tripod due to the extreme terrain I work in with redwoods.
https://www.ebay.com/itm/AdirPro-Mini-1 ... SwNydbUP--
Last edited by M.W.Taylor on Tue Oct 16, 2018 10:44 am, edited 1 time in total.

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F.Jakobsson
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by F.Jakobsson » Tue Oct 16, 2018 10:30 am

Michael,

Thanks for explaining the leapfrog method with prism and pole! Although my English is not too bad, a graphic illustration would of course be the icing on the cake...

Fredrik

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Erik Danielsen
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by Erik Danielsen » Tue Oct 16, 2018 6:35 pm

Thanks for the detailed explanation. I've had to make use of intermediate reference objects at times but expanding that to the "leapfrogging" method sounds even more versatile. I had also wondered about using some sort of reflector and the laser in filter mode- sounds like a proper prism would be the most precise approach.

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Don
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by Don » Tue Oct 16, 2018 10:30 pm

Although I am drawing on experiences gained in the mid-90's, while working on the Church National Forest doing timber sale traverses, we found the right balance of accuracy and expediency with a Criterion 300 (a yellow brick of a laser hypsometer). The feature that enabled us to get work done fast and well was the use of a one inch parabolic reflector for a target. the Criterion's role in this was an audio signal that varied with the strength of the reflectors return...as the pitch increased to a near shriek, you took your reading...the "whole" in the forest needed was incredibly small, and often difficult to make out visually. Closure errors on the traverses were routinely better than 1:2500.

I suspect such an audio strength signal might be an advantage in dense forests such as the redwoods...
-Don
Don Bertolette - President/Moderator, WNTS BBS
Restoration Forester (Retired)
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John Harvey
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by John Harvey » Tue Oct 16, 2018 10:40 pm

Great finds as always guys!
John D Harvey (JohnnyDJersey)

East Coast and West Coast Big Tree Hunter

"If you look closely at a tree you'll notice it's knots and dead branches, just like our bodies. What we learn is that beauty and imperfection go together wonderfully." - Matt Fox

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Larry Tucei
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Re: New Eel River LiDAR reveals more 350' class redwoods

Post by Larry Tucei » Thu Oct 18, 2018 2:30 pm

Michael-
Congratulations to you and John on your discoveries! I always enjoy the great western trees.
I sure would like to visit some of the Forests in California sometime in the near future.
Larry

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