James, The idea was mentioned before. The original TDI or tree dimension index was to include crown spread as one of the parameters, however because of the lack of sufficient data, in implementation it generally only includes girth and height. Certainly crown spread is a valid measurement. it is meant to represent to some degree the size of the crown of the tree. This is the part that is photosynthesizing and providing energy for tree growth. The crown also should be considered in terms of height, volume, and density. But still crown spread is a meaningful number in my opinion. I posted last year some ideas about using a series of crown shape diagrams along with crown spread and tree height to calculate approximate crown volumes. PDF General Dscussion I would like to see some people try to use the concept in the field. Larry and did some calculations of Live Oak crown volumes.
The problem with crown spreads in the forest is that they overlap and it is often difficult to distinguish without much work which branch belongs to which tree. I even made a device with a 45 degree mirror and a small level that would let me sight upward without bending mu head upward (and tripping and falling down) to make finding the lateral extent of the crown easier to locate. The big problem with the accuracy is people misjudging the point where they are directly under the branch tip. This can be done with a clinometer looking straight upward or with my little device, but judging the point from underneath without help is difficult and may be off many, many, feet. Another consideration is that the higher up the widest part of the crown, the more difficult to locate the point directly underneath the branch tip. In the forest also the crowns are often more irregular in shape, density, and vertical distribution than they are in open grown trees. In a forest setting, as Will suggests, the crown spread measurement may because of these irregularities have only a limited meaning, but certainly in open grown trees or in forest trees with a distinct definable crown they are worthwhile. And where important, even in forest grown trees such as the tree may be a champion, or is exceptionally large for the species it is worthwhile to try to collect the crown spread with the other measurement data - and a GPS location!! The best method in my opinion is the spoke method, where a series of shots are made from the crown tips to the edge of the tree trunk in a spoke like pattern. 2X the average of these spokes is the average crown spread of the tree. Maximum crown spread is the greatest distance from branch tip to branch tip and may not pass directly through the trunk. The specifics for the measurement for the longest limb is still being debated. One argument suggests it should be horizontal offset from the outermost branch to the projection above the center of the tree, one suggests it should be the horizontal offset from the outermost branch tip to the collar of the limb where it attaches to the trunk, and a third has suggested it should be the path length from the outermost tip along the branch itself to the collar at the base of the branch. http://www.nativetreesociety.org/measure/longlimbs/longest_limbs.htm Ed Frank http://nature-web-network.blogspot.com/ http://primalforests.ning.com/ http://www.facebook.com/profile.php?ref=profile&id=709156957 ----- Original Message ----- From: James Parton To: ENTSTrees Sent: Sunday, January 10, 2010 2:39 PM Subject: [ENTS] Re: Rucker Spread Index? Will, If they are tedious for you then I am gonna have fun learning...ugh.....but yes, I can see spread is harder to do. I figured that most sites probably would not benefit from having a RSI but Congaree might be one exception. JP On Jan 10, 1:43 pm, "Will Blozan" <[email protected]> wrote: > James, > > Good question, but one I don't have a good answer for. Spread measurements > are a tedious formality to me, and I would not be interested in searching > out the widest or average spread on a site just to have it. I am not sure > they would be meaningful data and are notoriously prone to error due to > subjectivity. > > 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: Saturday, January 09, 2010 2:07 PM > To: ENTSTrees > Subject: [ENTS] Rucker Spread Index? > > Bob, Will, Ed. > > ENTS uses Rucker Height Index and sometimes Rucker Girth Index to > acertain a forest. Has anyone ever thought of a Rucker Spread Index? > Would it be of any real use? I thought of that at Congaree since we > did average spreads on quite a few trees. > > James P.- Hide quoted text - > > - Show quoted text -
