Bob, Thank you for the in-depth explanation of crown spread. It probably will take me a little time to get proficient doing it and get really accurate figures. But I would like to get into doing this tree measuring stuff good and do it right. I will bookmark this post and use it for reference as I have done Will's diagrams.
Yesterday, while measuring in the EATON/Julian tract of forest I measured a wide-spreading White Oak. I attempted to find both the widest and narrowest area of the crown, fortunantly they were almost directly opposite of one another. I took four measurements to the trunk at 4.5 feet while standing straght under the tip of each limb, which I did verify by using the clinometer as you and Will recommended. The wide measurements I used the laser while the narrow I had to use the tape since it was under the minimum range of the laser. After doing the measurements I added the wide measurements together counting for the trunk diameter to get a single figure for the widest spread of the tree. Then I did the same for the narrow measurements. Adding the two together counting the trunk diameter to get a single figure. Then I averaged the two on the calculator to get the average between them to get average spread. I know it could be more precise, Multiple measurements made while circling the tree would give more precise results and another thing I was alone. Another person under the limb opposite opposite of me with a reflector would have made it easier for me and I know the crowns center is not always dead center over the trunk. Being alone, I had to improvise. I think I got it in the ballpark though. Thanks: James P. On Jan 8, 11:00 am, [email protected] wrote: > James, > > Crown spread measurements are a challenge, more so than simple explanations > and measurement diagrams would lead the beginner to believe. Measuring the > crown spread of an in-forest tree is an obvious headache to anyone who has > tried it a few times. Open-grown trees in a field or park with full access is > another matter. In ENTS we often find ourselves measuring forest-grown trees > in difficult terrain. > > The traditional way is to measure the longest and shortest spreads and > average then average them. Lots of luck. An alternative is to fin what you > think is the longest spread, measure it and then rotate 90 degrees and take > another spread measurement and average the two. These are the to methods of > measuring crown spread that are commonly described. But without spending a > lot of time, how do you know you've found the longest and shortest spreads? > And even if you have, do they capture the average spread well enough? > > F or trees that lend themselves to circling around, the best way to determine > average crown spread is to circle the tree and shoot to the trunk from points > along the drip line. If you're on sloping ground, shoot to the trunk with > your laser and clinometer and compute horizontal distance to the center of > the trunk by the calculation H = D x cos(A) + R, where D is the > laser-measured slope distance to a point on the trunk, A is the angle, R is > the trunk radius, and H is the computed level distance or spoke length. If C > is average crown spread, then the final formula is: > > C = 2 x [SUM(H+R)]/N where N is the number of readings. C is obviously just > double the average of all the H spoke lengths taken to the center of the > tree. Of course, if you are measuring in yards, of course you have to > multiply the final result by 3 to convert to feet. If you had your laser on > meters, the factor is 3.28084. > > Alternatively you can compute C as: > > C = 2 x [SUM(H)/N + R] as an algebraic simplification of the first formula. > > Whether you add R to each spoke or to the ending average length of the > spokes, don't for that step. Since radius varies with height, best to shoot > to the trunk at a predetermined height or spot on the trunk where you've > taken the girth and calculated the associated radius. R = C/(2 * Pi). This is > usually at 4.5 feet, but doesn't have to be for the crown spread > determination. Visibility and access always have to be taken into > consideration. All of us who measure trees know this, but the simplified tree > diagrams never discuss actual field conditions and how to deal with obstacle > that obscure visibility. > > The more radial shots you, get the better. Just circle around the trunk > following what you think is the drip line - if you can. Use the clinometer to > position yourself at the extreme edge of the limb. You need to insure the > angle is 90 degrees. > > Where a tree hangs over a roof, you have to get increasingly inventive. If > you stand at the trunk and look out to what appears to be the greatest > extension of the limbs over a roof, you can use H = D x cos(A) + R to > calculate the horizontal distance away of what you can see as a tip. Of > course, this may not be the fartherest extension, but you have to measure > what you can see. > > One final point worth discussing, are we attempting to measure the spread of > the crown as defined by branches and limbs, as opposed to the absence > thereof? For example, suppose in circling the tree following the drip line, > you reach a point where there are no branches of any consequence protruding > out from the trunk, just small foliage near the top. You are really in a gap > between outstretched limbs. Would you take spoke measurement here? Moving a > few feet left or right wold put you back under overhanging foliage. Should > that be your choice? It is for me. I don't typically include in my > determination of crown spread places where limbs are missing, where you could > follow a gap between foliage/limbs right up to the trunk or nearly so. We > don't usually address this technicality in our discussions. > > Crown volume is an ENTS calculation that we have attempted to perfect to > better capture those marvelous live oaks of Larry's. But despite playing with > formulas a lot, I've never been satisfied with the results. Ed has had some > good ideas. Basically, we are attempting to measure a highly irregular, > partially filled space. Not an easy thing to do even for the most cooperative > of trees. > > Hope this helps. > > Bob > > > > ----- Original Message ----- > From: "James Parton" <[email protected]> > To: "ENTSTrees" <[email protected]> > Sent: Tuesday, January 5, 2010 11:38:12 AM GMT -05:00 US/Canada Eastern > Subject: [ENTS] Re: Laser History and Measuring Tree Spread. > > Bob, Thanks for the explanation. One thing is for sure, I enjoy measuring > trees by this method when I am out. I think I have it pretty much down but > still I need more practice at being proficient at it. I was going over what I > learned at Congaree last year, doing tree spread. They are a couple of ways. > Take two measurements, four spokes and average them. Say 15y by 20y. You > would add them together and divide them by two to get the average. right? And > then take the answer and times that by three to get it in feet. 15+20=35 > divided by 2=17.5 x3 = 52.5 That is 52.5 ft average spread. I also seen in > Congaree where multiple measurements are made by circling the tree making > multiple measurements for improved accuracy. I looked up and read on how to > measure max and average spread on the website but wanted to know whether I > had the averaging number formula right. I never was a math wiz. ~laughing~! I > find it awesome that ENTS and a few independents have influenced tree > measuring so much that Nikon and others now produce rangefinders to cater to > that need. As you stated, before us rangefinders were made primarily for > sporting activities. Hunters still use them a lot, for example. I have to > thank all ENTS but especially You, Larry Tucei, Will Blozan and Ed Frank for > helping me learn this amazing method. I would encourage all non measuring > ents to learn it. It really is fun! James Parton On Jan 5, 9:39 am, > [email protected] wrote: > James, > > BVP was independently using the sine > top sine bottom method first. There may have been others as well, but I'm > unaware of who they would have been. Will Blozan and I developed sine top and > sine bottom for ENTS. We later discovered that BVP and been using it for a > long time. Colby Rucker later joined Will and me and became known for his use > of long poles to get a better fix on the lower measurement. Colby was just > great. I miss him a lot. We all do. > > BVP was the one who introduced Will > and me to the Litespeed 400, a Bushnell laser. I got one and so did Will. > Everything was uphill thereafter. The rest is history. > > In terms of the > tree math, my strong suit has always been mathematics. I developed > mathematical models in my work while in the Pentagon and have taught math and > statistics at the college level. So, tackling the problem in a mathematical > way conforms to my nature. I say this because it has always come as a > surprise to people outside the world of forestry that such basic calculations > as we use haven't been in practice for decades. I always explain that those > calculations were not possible prior to the introduction of the laser > rangefinder. As to the expertise of mensurationists, they know the math. It's > elementary, but they don't spend the time decoding hard to measure trees in > forest situations. It's rather like knowing some principles of animal > tracking versus being out there doing it. It took me three separate trips to > tie down that tuliptree in Montpelier. I'm within +/- 0.5 feet of the twig I > was measuring, but the effort required speaks to the difference of pointing, > shooting, and writing down some numbers versus getting it right. ENTS knows > better how to do that than any other group in the East. Of that, I have no > doubt. > > The Forestry 550 does measure tree height by our sine top, sine > bottom method. The TruPulse does it also, but not by the built in height > routine. It requires mores steps. BVP's Impulse Laser also does it right, but > not by the built in routine. He also must use more steps. The OPTILOGIC > appears to do it by the old tangent method. Pity. > > Before ENTS people were > using laser rangefinders in sports and other endeavors, but judging by the > feedback we have gotten, ENTS has been really the only show in town in terms > of employing laser rangefinders in tree height measuring. There's no way of > knowing who might have been out there in tree-land doing it on their own. > They didn't come forward. > > The tangent-clinometer method was used before > ENTS. It has been in use for decades. I suspect that early measurements of > standing trees employed this method with some instrument being used to > measure the vertical angle. The method of similar triangles would also have > been used. Descriptions of equipment used and measuring methodology have been > lost, if they were ever known. Thus, we get reports of astounding tree > heights, but no way of verifying them. We'll never know what grew in > centuries past. > > A laser by its self can be used as you describe. However, > looking upward and trying to shoot exactly straight up (90 degrees) is harder > than one might imagine. When you think you are looking straight up, it is > often at an angle of 70 to 75 degrees. A short make shift plumb bob can be > used to create a true vertical line. > > I think this covers everything. > > > Bob > > > > ----- Original Message ----- > From: "James Parton" > To: > "ENTSTrees" > Sent: Monday, January 4, 2010 10:47:21 PM GMT -05:00 US/Canada > Eastern > Subject: [ENTS] Re: Suunto vs. iPhone > > Bob, > > ENTS came up > with the Sine-Top Sine-Bottom method of measuring, right? > I also know that > some others have used lasers to measure trees more > recently? Has ENTS > inspired the use of laser rangefinders as tree > measuring tools so much to > grab Nikon's attention to build a laser > specifically for measuring trees? > And then there is those Tru-Pulse > lasers and the one that BVP uses. Was > lasers being used of any > frequency before ENTS? I have always thought the > tangent clinometer- > only method was in use before You and Will developed > our highly > accurate method. I also know that a laser can be used by itself > from > under the tree if the top can be found as in a decideous tree in > > winter without the need of the clinometer. > > Fill me in on laser usage > history. > > James Parton > > On Jan 3, 3:19 pm, [email protected] wrote: > > > Carolyn, > > > The Nikon Forestry 550 does it all. It is also fairly > pricey. You select the height mode, shoot the crown, shoot the base, and read > the calculated height from the LED. No math. No fuss. No bother. > > > Bob > > > > ----- Original Message ----- > > From: "Carolyn Summers" > > To: > [email protected] > > Sent: Sunday, January 3, 2010 2:35:23 PM GMT > -05:00 US/Canada Eastern > > Subject: Re: [ENTS] Suunto vs. iPhone > > > Are > there any tree-height measuring devices that do the math for you? I > > never > took trig. > > -- > > Carolyn Summers > > 63 Ferndale Drive > > > Hastings-on-Hudson, NY 10706 > > 914-478-5712 > > > > From: Beth > > > > Reply-To: > > > Date: Tue, 22 Dec 2009 15:57:09 -0800 (PST) > > > To: > ENTSTrees > > > Subject: [ENTS] Suunto vs. iPhone > > > > A Small Comparison > between Suunto and iPhone Clinometers > > > > Since some of us now have > iPhones and have downloaded the > > > Clinometer application I thought that > someone needs to compare the > > > iPhone to the Suunto clinometer. Today I > took 14 measurements each > > > while sitting on my couch to a ceiling > heating/AC vent. I then > > > measured my eye height, the ceiling height, and > the distance from my > > > eyes to the tape measure hanging from the vent as > a plumb bob. These > > > measurements were: ceiling height = 96², height of > the eyes = 38², and > > > distance to the vent plum bob = 219². I used the > measurements to > > > calculate the angle I was trying to measure with the > Suunto and > > > iPhone. Before taking my measurements I calibrated my iPhone > > > > clinometer according to the instructions. I also had the following > > > > settings: Fast approximation-on, Beep on lock-on, wait for lock > > > > accuracy of + 0.1o- all the way to the left (+ 0.1o), disable auto- > > > > lock-off, and 3D glass effect-on. > > > > The first thing that I do in order > to calculate the angle A was to > > > calculate the distance from my eye to > the ceiling; 96²-38²= 58². > > > > Since Tan A = a/b, we can rearrange the > equation to find A by dividing > > > both sides by Tan. Since 1/Tan =Arc Tan > the equation is A = (a/b) Arc > > > Tan. Filling in this equation with the > data we get A = (58/219) Arc > > > Tan or A = 14.8336707057. Taking > signifiginte numbers in mind I am > > > going to say the angle is 14.8o. > (Note: I calculated this after > > > gathering the data as not to influence > the clinometer data) > > > > Now for the clinometer data: > > > Suunto iPhone > Suunto iPhone > > > 15.5 15.2 14.5 15.4 > > > 15.0 14.9 15.0 15.2 > > > 15.0 > 15.1 14.5 15.2 > > > 15.0 14.1 14.5 15.1 > > > 15.0 15.0 14.5 15.7 > > > 15.0 > 15.2 15.0 15.5 > > > 14.5 15.1 14.5 15.2 > > > The means were 14.8 and 15.1 > for the Suunto and iPhone respectively > > > with standard deviation of 0.31 > and 0.35. > > > > The one thing I noticed in my raw data is with the Suunto > my highest > > > and lowest angles were 15.5 and 14.5 whereas with the iPhone > they were > > > 15.7 and 14.1. I can think of at least two reasons why. 1) I > have > > > more experience with the Suunto than I have with the iPhone and 2) > the > > > Suunto has a line to help repeatly ³hit² the same spot whereas the > > > > iPhone you are just looking down one side of the phone. > > > > I also > noticed after calculating the angle (14.8) the Suunto average > > > was > closer than the iPhone¹s (14.8 vs. 15.1). Now is 0.3o difference > > > > significant? Bob has more experience with the Suunto than I do and he > > > > has stated in the past that can read it to the nearest 1Ž4 o. I myself > > > > can only read it to the nearest 1Ž2o. Given this I believe that a > > > > difference of 0.3o is. > > > > How can the iPhone be improved? If one would > add a sighting device on > > > to the iPhone this could help ³hit² the same > spot repeatly. Obviously > > > this can not be same one that is used in the > Suunto¹s, looking through > > > it with an optical illusion. Maybe a tiny gun > sighting built into the > > > volume and/or ringer buttons on the left side. > I think someone > > > thought of this earlier. With the sight and practice I > believe one > > > could the angle down to the nearest tenth of a degree. With > the > > > Suunto one can only really estimate anything less than 1 degree. > > > > Beth > > > > -- > > > Eastern Native Tree > Societyhttp://www.nativetreesociety.org > > > Send email to > [email protected] > > > Visit this group > athttp://groups.google.com/group/entstrees?hl=en > > > To unsubscribe send > email to [email protected] > > > -- > > Eastern Native > Tree Societyhttp://www.nativetreesociety.org > > Send email to > [email protected] > > Visit this group > athttp://groups.google.com/group/entstrees?hl=en > > To unsubscribe send > email to [email protected] Hide quoted text - > > > - > Show quoted text - > > -- > Eastern Native Tree > Societyhttp://www.nativetreesociety.org > Send email to > [email protected] > Visit this group > athttp://groups.google.com/group/entstrees?hl=en > To unsubscribe send email > to [email protected] Hide quoted text - > > - Show > quoted text - > > -- Eastern Native Tree Societyhttp://www.nativetreesociety.orgSend email to > [email protected] Visit this group > athttp://groups.google.com/group/entstrees?hl=enTo unsubscribe send email to > [email protected] Hide quoted text - > > - Show quoted text -
