Email on measuring hieght

[John Paul Sanborn]

John Paul,

I saw references to the WI DNR big tree list on your WI champion trees forum which came up on a web search that I had conducted for something else. I have found the height measurements in the DNR list to be completely unreliable on most of the listings that I have attempted to verify. Many of the larger girths are mismeasured multistemmed trees. The MacArthur pine was even listed twice. I have been unable to verify any of the white pine heights listed, other than the MacArthur pine. Either the locations were poorly specified or the trees had fallen or been removed. The recent heads of the program were unresponsive to correcting errors in their list. A friend of mine, Robert Van Pelt, used to manage the program more carefully. He moved to Washington and continues his work there, http://www.forestgiants.com/. When I get the chance, I have been roaming northern Wisconsin and the western upper peninsula of Michigan. I have been associated with ENTS for about 7 years, http://www.nativetreesociety.org/. We already have an unmoderated forum on http://www.nativetreesociety.org/entstrees/discussion_list.htm. Some members of our group do organized climbs for height verification and for volume modeling. Some arborists within our group have been very active in treating hemlock trees for hemlock woolly adelgid.

We have been using a laser clinometer combination to get heights to within a foot or two, while some trees in the DNR and American Forests lists for Wisconsin and elsewhere are off by 20-30 feet or more. Former national champion white pines on private land in the Huron Mountains of Michigan were listed as up to 200' tall while a friend of mine couldn't find anything higher than the 130's in the area while doing permitted ecological research there. Due to the errors in the state and national lists, we have been creating our own lists of trees measured with accurate methods only. By my data of trees that I have measured with clinometer and laser, the tallest eastern white pine in the legal boundaries of Wisconsin is 10.7' cbh and 150' tall on the western extent of the Cathedral Pines in the Nicolet National Forest. When I had permission to measure within the Menominee Tribal Enterprises, we measured white pines to 165-167' tall with girths of 13-14' with some snags in the 16-18' range with heights in similar ranges, yes bigger than the MacArthur pine in it's prime. We had leads on state record sized northern red oak there, but our permission expired after our contact there, Dan Pubanz, moved on to become an SFI auditor.

I just thought I'd send a few big tree ramblings your way to see if it triggers a response as to what you've been up to here in Wisconsin in parallel with my efforts, I'm hesitant to get involved with the state program due to it's problems of the recent past, lack of due diligence and enthusiasm, and I don't want my personal contact information posted on a public web site, either.

Regards,

Paul
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From: John Sanborn


Hi Paul, your concerns are the same as ours. People fudging measurments to get "their tree" posted in the book. Also the underfunded state aspect of the program.

DNR would like it eventually leave their perveiw, one of the reasons I asked ArboristSite to lend the server space. WI DNR finally gave Ian Brown, the current person to have the CTP as one of his many duties, permission to work with us at ArboristSite.

Most of us are micro mini companies, and LASER clinometers and GPS are out of the question, though several of us have good pocket clinometers.

It is a big task here on cleaning the list up, but we do want to see it happen. Ian wants to streamline the prosess too.

JPS

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Paul wrote:

John,

I may have been misleading when I stated that I use a laser clinometer combination. I meant that I use a laser rangefinder together with a handheld clinometer. I only know a couple of people with the $2000-3000 Laser Tech laser/clinometer units. I use a Suunto PM-5/360PC handheld clinometer ($114 at Ben Meadows) and a consumer grade laser rangefinder, an older Bushnell YardagePro 1000. Many others are using Nikon ProStaff Laser 440's which are under $200 at many online stores and even Walmart. Even though the consumer grade units typically have 1 yard resolution, if you move back and forth until it increments to the next higher range, it often has better than 1 foot accuracy to the higher number at the point where it increments. The result is that tape drops on trees 140-185' tall are usually within a foot or two of our consumer laser measurements.

If you don't use a laser, then I assume that you are taping to the trunk and using the clinometer at that point. The tape and clinometer only method often yields huge errors, sometimes 20-30% or more if the user doesn't triangulate a point on the ground under the point being measured. Often, this is difficult to do in a forest situtation where clear views of the top are rare and it is easy to confuse the branches with adjacent branches when moving around while trying to triangulate them. Tape measurements to the trunk and then a clinometer reading to the top are unacceptable unless you can confirm that the top is actually over the point on the trunk that you are taping to. The method is at it's worst at measuring leaning or wide-spreading trees.

I believe that most people don't intentionally exagerate the tree heights but are careless in their measurement methods. The tape and clinometer method is fine for estimating marketable bole length but fails on real world tree top measurements. We have recreated errors on previously measured trees, and in many cases the same mistake is made. The measurer measures to a point 100' from the trunk and then takes a clinometer reading to what appears to be the highest branch. But on many trees, the perspective from 100' usually causes the measurer to choose a a branch that is not the highest point (which may be obscured by lower branches) but is actually a very high side branch or adjacent leader at a measured angle that is significantly larger than that to the real top. The result is an exagerrated height. Sometimes, I believe that the former (now deceased) head of the Michigan big tree program learned by experience that he got the highest height measurements when he used the tape and clinometer method on the side of the tree with the longest branches. He may have thought that this tended to be the side of the tree with the highest branches instead of realizing that it was the side of the tree with the highest error for that method. Or, maybe he did it intentionally to get his spot in the books.

There are reasonable tree measuring guidelines on:
http://www.nativetreesociety.org/measure/tree_measuring_guidelines.htm

If you already have a clinometer with a degree scale and a reasonable investment on the rangefinder, you can use the sine calculation method described on the web page to get very accurate tree heights.

FYI: Our organization holds recurring annual events in Massachusetts and Pennsylvania that include climbs and measurement training, as well as big tree or old growth hikes. In Massachusetts, the climbs usually include 160-165' pines. In Pennsylvania, they usually climb 140+' hemlocks or ~180' pines.
http://www.cookforest.com/activities/bigtree/index.cfm
http://www.hcc.edu/forest/
There may be less organized events in Arkansas and Kentucky this year. Every year, Dr. Lee Frelich (forest ecologist at the U. of Minnesota) and I usually try to do one or several hikes in the Porcupine Mountains Wilderness State Park in the upper peninsula of Michigan, as well as other spots in Wisconsin or Minnesota.

I live near Burlington in southeastern WI and can verify tree heights if called upon, but I spend most of my big tree time in old growth or virgin forest looking for previously undiscovered giants. I also own land in far north central Wisconsin in the Mellen/Upson/Hurley area and can stop and verify tree heights anywhere on the way.

Regards,

Paul

 

[John Paul Sanborn]

From: John Sanborn

Paul,

We've only started doing this seriously, and most of it is in urban and homestead areas so usually we can see the tops. Though I've done some inner city ones where it was a POS to get it, only to find that the C measurment was much smaller then the one in the book.

I have a Brunton Clinomaster from Baileys. I've used Sean's didgital clinometer, and the three of us using it got measurments several feet apart.

I learned to take measurments from 2 different angles for the reson you mention. If the tip you measure in not over the trunk, you do not form a right triangle.

I've copied this to Dave R. of Tree Releaf in Greenlake. He has a red oak we measured just under 100ft that looks to have a higher point value then the current champ in the WI book. He may be interested in having you look at it with him.

I enjoy talkin to other tree people, climbing and big trees in general, so if you would like to get together for a climb some time...I'll be at the DNR/WAA conferance in Greenbay again, and Ian Brown will be giving a talk on the program too.

JPS

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John,

I have a Brunton Clinomaster as a backup clinometer. It works well, but I think that the Suunto has a slightly smoother movement that settles more readily on the correct inclination reading. It may just be an issue with the individual Brunton unit that I have, but otherwise, it works well and is very usable. Is Sean's digital clinometer just a clinometer, or is it integrated with a rangefinder, too? If not, it would make sense that you all would get approximately the same height calculation if you were measuring the same point on a tree from the same spot.

We have done very accurate height measurements without a rangefinder when we used a transit on a tripod. We would level the tripod mounted transit, zero in on the high point, and then tilt the tripod toward the ground under the tree and have a second person stake two points in line with the transit. We'd repeat the process at approximately a right angle and tie lines between the stake pairs to find the intersection of the transit lines. That point would be used to tape to the point where the clinometer reading was taken to get the height of the tree top above the height of the eye of the measurer. A point on a level line from the transit to the tree was marked on the tree top to get the height to base. This method was often within a foot or so of readings taken with a $3000 impulse laser. On hardwoods, we find that the highest points are often 5-20' from the trunk and rarely over it for most trees except for spruce and fir. With the laser and clinometer, we can also easily calculate the offset of the tree top from the trunk.

Our consumer laser plus clinometer readings are often within a couple feet on trees 140-180' tall. With the lasers, angle to the twig, size of the branch, leaf/needle density, etc all affect the reflections back to the rangefinder. My rangefinder tends to undershoot trees by 2-3 feet while it is within 9-12 inches of the displayed value on a tape measured distance to a large flat object like a cardboard box. Some of the newer, cheaper rangefinders are within a foot on the same trees.

Furthermore, you mention discrepancies on girth at breast height. That is one that really gets screwed up. I've attached a picture from a newspaper that unintentionally shows you how not to measure a tree. People often don't keep the tape tight and close to horizontal. They don't choose the proper starting level on the ground. They don't follow rules for multi-stemmed or low branching trees. Some intentionally route the tape over burls and loose hanging bark pieces. ArggghhH!!!

I'd love to get into tree climbing. When I was a teenager, my older brother inspired me to free climb 90' pines and hemlocks. More recently, he has climbed up to 150' or more up 225-250' tropical trees in Costa Rica and Ecuador. He is a naturalist who has studied birds and wildflowers. At this time, he is specializing in orchids and has discovered and named dozens of new species in the Andean cloud forest of Ecuador where he has lived for the last 15-20 years.

My friend, an arborist in North Carolina and has climbed and tape dropped many of the tallest trees in the eastern United States, including a 207' eastern white pine and 170+' tall eastern hemlock and tulip trees. I don't know if you'd ever drive a long way for a big tree event, but a trip to the Smokies to meet and climb with Will would be worth it.

Regards,

Paul

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Hi Paul and JPS,

I actually just got back from Eagle River.

Paul, I think that I know the white pines that you measured (The School House Pines) in the Menominee Res. I saw them about six years back with a friend and they are spectacular! My height estimate (visual) was 165’ so it is very cool to hear that they are a bit bigger. I have decent DNR contacts so let me know about access.

Sorry for the delay but I thought that I’d get in on the conversation.

Sean

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