I wrote this in the Arb. Lit. forum and decided to move it here as an Arg. Lit. item to stir up some juices:


I have a lot of problems with Mattheck's works. It has been my plan to write very specific challenges to the concepts and assumptions he has offered. For now, I'll keep it simple.

Trained, traditional engineers--or physicists--are most comfortable in the world of phenomena reduced to equations, and much is to be said in support of that inclination. For me however, Mattheck tugs and pulls the issues of trees over into this often tidy world whether or not the issues fit.

For example, in the finite element method of computer analysis he provides, the hidden truth is that the analysis works on monolithic materials, steel, etc., with the stresses, failures, and propagation's of problems operating in a single type of material consistent through its mass. The photos of FEM are persuasive in that they are windows of the "new science," but they are also deceptive if they're done about apples when we're talking about oranges.

Klaus shows the corresponding stress and patterns of stress in making a hole in a homogeneous material which is to remove an amount of an area that should be available to share the loads. The patterns of stress concentration are understandable and, yes, he is teaching us valid and useful information. Engineers build that information into their designs to make better and more successful outcomes. Liberty ships were lost because of crack propagation that continued unchecked until the ship split in half and sank. The awareness of that probability lead to anticipation and reinforcement with future designs.

Mattheck takes this one attribute of monolithic materials and expands it to trees. Holes in trees are "flaws" and we can suddenly infer the structural liabilities of trees from a touch of sophomoric text on engineering equations. In same-stuff materials, there are engineering solutions--reinforcement, drilling holes in the end of a crack to spread the load, and in the last hundred years, composites and laminations. Oddly, trees thought up laminations more than a hundred million years ago.

Indeed, trees are the quintessential proponents of living composite lamination. Klaus's sense of flawed structure is quite distant from them. Mattheck, to me, stops abruptly when what he theorizes resembles an equation. See, he says, it fits--so, let's get on to the next question... I'm sorry. I have a difficult time with that especially when it's presented as dogma to an information-starved audience like those of us in the arboriculture business.

The approximation of plate steel with a hole under tension (the plate pulled at each end) has very little to do with a tree. At best, it is illustrative of a "plate steel with a hole under tension" in Engineering 101. Mattheck would have us stop at comfortable linear equations, when trees are unquestionably non-linear.

His FEM offerings also assume that growth in a tree is akin to the thermal expansion of a homogeneous material. Well, it's a shame that trees haven't read his works; they grow completely differently and the differences are so substantial that he is only giving us a great deal of simplistic misinformation instead of what we need.

I cannot, in good conscience, evaluate a tree based on his pronouncements. People would be shocked if they found out the thinness of the base from which his hollow tree failure "guidelines" are built. But in a world where we'll cut down a tree at the hint of a shadow of a lawyer, what difference does it make?

Maybe I'll present it as a paper in detail at the ISA August conference.


Bob Wulkowicz

Reply to post by Bob Wulkowicz, on April 09, 2000 at 12:50:02:

Bob,

I think there are two (at least) key issues surrounding the "culture" of all this.

The first I understand pretty well. It's a phenomenon that many of us have observed and that you describe quite well: "...an information-starved audience like those of us in the arboriculture business." Whether it's from an honest and responsible desire to base arboriculture on "science" or a more self serving desire to have a good sales pitch or an awestruck self esteem thing there's this pattern of grasping for and locking onto nuggets of theory or "fact" and making icons out of the theorizers. There are lots of groupies. "If so and so says it who are we to question?"

The second I'm just starting to get a handle on. We've seen it for a long time in the industry sponsored research on pesticides... "of course this chemical is good." There are commercial products coming to market which are by-passing industry third parties and are the business enterprises of the theorists themselves. Layer onto this researchers wandering along the edges of their fields and along the edges of charted territory and you add some more lack of certainty. And finally add in rivalries among theorists which propell them into attacks and defenses against each other rather than refined attacks on the unknown.

Combine those potential biases with a grasping and non-scientific audience and what do you get? I guess you get overstatements of certainty.

What should we be getting? Maybe a little better understanding, sharper questions, another step along the way. More tools to apply differently to differing fact patterns rather than allegedly universal rules. The fault is as much among the receivers as the providers.

OK moving back to your specific observations...

I think you're not alone in questioning. There's another German scientist named Lothar Wessoly who is all over Mattheck. As nearly as I can tell the science of Mechanics is divided into Statics, Dynamics and Strength of Materials... Mattheck is a Strength of Materials guy and Wessoly is a Statics guy. Kim Coder is setting up a May, 2001 conference on tree mechanics and I think clarification of these differences may be on the agenda.

A number of the Ph.D. types (no names to protect the innocent) are reserved in their application of Mattheck data and "rules" but not necessarily rejecting of it all.

Next... Assuming Mattheck is a Strength of Materials guy one would suspect he has or should have made some consideration of the differences between steel and organic materials. In fact some of his work involves computer modeling of the similarities among trees, animal and human bone, bird's beaks and so forth. Can he have ignored that the material propertis are different from a steel lifting hook? Dunno.

Have you looked at Mattheck's "windthrow" materials and do you have any comment about them?

Scott

Reply to post by Scott Cullen, on April 09, 2000 at 12:50:02:

Scott,

Now that the "Ethics" section is gone are we free to ask unethical questions? ; )

I have tried to find something by the German researcher "Lothar Wessoly" with no success. Where have you found his research?

Wayne

Reply to post by Wayne, on April 10, 2000 at 07:10:15:

That's Wessolly, Scott/Wayne. I did a search in the Agricola and Biosis databases, after reading some poor translations without figures of articles that came through Russ from Mark Hartley originally, I think.
I could not find the main original periodical, nor could ILL at Cornell, so I guess there is an error in the journal title ("Stadt und Grun"), but I did find a recent article of his in English that I intend to look up soon.
Here is the info from BIOSIS:

TI The mechanical properties of Norway spruce (Picea abies (L.) Karst) as
a function of different growth conditions.
AU Bruechert-F. Sauter-U-H. Wessolly-L. Speck-T.
JT Journal of Experimental Botany.
SO Journal of Experimental Botany. 47 (SUPPL.). 1996. 93.
IS ISSN 0022-0957.
LG English (EN).

His work looks like important stuff for us all to digest.

Reply to post by Wayne, on April 10, 2000 at 07:10:15:

Oops! The Ethics section is NOT gone. I updated the header file, and somehow left it off the list. It's back where it should be.

webmaster

Reply to post by Jerry Bond, on April 11, 2000 at 08:39:58:

Near as I can tell, Stadt und Grun is a popular magazine (roughly 'Town and Country'), not a referreed periodical. I could be wrong on that.

As Scott pointed out, this work is a counterpoint to Mattheck. It should be scrutinized within the context of the work, like all others.

We are indeed "knowledge-starved arborists", always looking for the newest method, the more accurate technique. This is not new- it was happening decades ago when Davey and Bartlett started their research labs. The problem we face is not just getting the information, but being careful to analyize it first, keep it in context, and apply it with foresight and descretion. A very tall order, indeed. We tend to take small bits of information, push it to the top of the list and claim it to be the ultimate. That is not necessarily bad, nor should we wait until all knowledge had been gained to apply the little we know. Field testing and practical application are often the driving forces for the next stages of research.

Case in point- on the mycorrhizae listserve last year, several top researchers in that field lamented that practitioners were going to far too fast, and making claims or using products that were not entirely known. But if we wait for the research to be completed, we may wait forever, and miss many opportunities to benefit trees in the process (or to harm them, if we are not careful). So a balance is needed. The research must continue, and we must continue to apply what we know judiciously. What we learn from each aspect helps drive the other forward.

Reply to post by Jerry Bond, on April 11, 2000 at 08:39:58:

Here's a link to a reprint service for German planning literature. I think some of the publications Wessolly published in are on the list.

Reply to post by Jerry Bond, on April 11, 2000 at 08:39:58:

Jerry,

The title of the publication is correct.

Mark

Reply to post by Russ Carlson, on April 11, 2000 at 09:41:28:

I remebered seein his name in some footnotes, there is a translaion of one of his

NEUE LANDSCHAFT 11/96 S. 847 - 850 TUIN & LANDSCHAP 15/1998 S. 18 - 21 More than two
thousend investigations of tree statics form the basis for answering the question as to how safe
a hollow tree is: a report by Dr.-Ing. Lothar Wessolly of Stuttgart

with bibli at the http://www.tree-consult.org/englisch/hollow.htm link and a few others came up.

Reply to post by jps, on April 11, 2000 at 12:42:06:


The abstract for a presentation at the ISA Conference this year:


TITLE: Re-examining Mattheck's Assumptions

LEAD AUTHOR: Bob Wulkowicz

PRESENTATION STYLE: 25 minute Presentation


PAPER ABSTRACT SUMMARY:


Dr. Claus Mattheck has made many substantial contributions to our understanding of the structures, stresses, and strengths of trees. He has offered new techniques and engineering methods that can aid practitioners and scholars alike in the evaluation of trees and their hazards. The Finite Element Method of structural analysis, for example, uses computer-generated programs that show the graphic presence and magnitudes of stress and load in a subject's shape and material. These visualizations are extremely persuasive and give the arboricultural community a sense of new directions that seem to better explain a tree's structural elements and growth than any previous theories.

However, these FEM programs are generally applied to simple monolithic materials such as steel, etc., and may not be as definitive for the complex laminated and composite materials of the wood structures of trees. One may argue that they are good enough, but if Mattheck's assumptions and inferences are approximations that seem familiar and comfortable to engineers as linear equations, is that sufficient for us to simply accept them for trees known to be non-linear in many components? And, if we intend to use these programs and their conclusions for deciding the safety and longevity of trees, it is reasonable to examine and challenge the underlying causal assumptions to determine if analytical techniques for steel and concrete will also be accurate predictors or structural explanations for trees.

In the same regard, Mattheck's explanations and illustrations of growth in trees utilizes a thermal expansion technique that works well for monolithic materials, but may be difficult to rationalize as equivalent for trees whose three-dimensional growth is generated by a sheet of cambium. These are two completely different phenomena; thermal expansion is a physical attribute of a material proportional to its heat; and a tree's diameter growth by its cambium utilizes a living engine of many variables, a biological design that has evolved over a few hundred million years which may not yet be able to be captured or categorized in a few tidy engineering equations.

The author will present alternative perspectives and explanations in a discussion of the illustrations and narratives of Dr. Mattheck.


Bob Wulkowicz

Reply to post by Scott Cullen, on April 09, 2000 at 12:50:02:


Have you looked at Mattheck's "windthrow" materials and do you have any comment about them?

Scott


Sorry for the delay in getting back. I did look at some of his research and background comments--and was suprised at how many fallen trees were looked at in a very few days. Enough perhaps to confirm a predispostion toward some engineering equations. Not enough time and exposure, in my world, to the varying conditions and circumstances to allow the trees to teach new perspectives. Why revisit the issues if we already have the answers?


tubs