Will, Thanks. I knew from watching and helping out at Congaree, and plus it's a bit of common sense that crown spread does not usually center on the trunk, but I did not know how to do it alone. You advice here will be a big help. It will be another use for my hiking stick! That never occurred to me.
Thanks Master Jedi! James On Jan 8, 12:47 pm, "Will Blozan" <[email protected]> wrote: > James, > > Yes, max spread would be from a point under the branch extensions and NOT > through the trunk. When alone I place a target on one side (stick, camera, > notebook) and go to the other and shoot back. In the forest there is often a > smaller tree trunk under the opposite crown point and I shoot to that, take > the angle and convert to horizontal. > > Will F. Blozan > President, Eastern Native Tree Society > President, Appalachian Arborists, Inc. > > "No sympathy for apathy" > > > > -----Original Message----- > From: [email protected] [mailto:[email protected]] On > Behalf Of James Parton > Sent: Friday, January 08, 2010 12:06 PM > To: ENTSTrees > Subject: [ENTS] Re: Back to James on crown spread > > 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. > > ... > > read more »- Hide quoted text - > > - Show quoted text -
