I am presenting a report (below) that I generated following a tree removal. I am looking for comments so that I may learn ways to improve my approach in future.
In lieu of a diagram, I will add a written description of the tree base here: There was an extensive root flare, which I describe as the exposed limits of the root crown. Decayed wood along the top of the curb could be kicked loose. The tree had overgrown the top of the curb before it died on the street side.
The live wood, outside the reaction zone was "C"-shaped and on the side opposite the street. Most of the wood inside the reaction zone was still not visibly decayed, but was darkly colored. My understanding is not clear about whether any live cells remained there, but I assume not. Live or dead, it seemed to me(after cutting)to still offer much support.
My concerns were mainly with the portion below. That has not been ground out yet, but I plan to view that as it happens, looking for more information.
I wrote the report is to satisfy concerns about why the tree was taken down. The tree was not tested using any devices to determine the internal decay profile. There is not a person employed here more qualified than me to make this judgement. It is also not something that would be likely done by an outside professional resource. I will admit that my concerns and conclusions developed over many years of observing this tree (20+), and are arguably subjective.
I will keep an open mind to comments, whether supportive or critical. Thanks.

Tree Removal Report (Monday, February 18, 2002 Mark Goodwin, Tree Trimmer)
Sugar Maple, Acer saccharum
Location: Map Grid 31, Tree 43 (1st St. north side park strip, near Laxson Auditorium)
Removed: 2/13/02-2/14/02
Height: 60' to 70'
DBH 27" (average)
Root crown (exposed): 5.5'x10.5'.
Diameter of trunk at 2 ft.: 28" min. x 32" max.
Annual ring count: about 80 (or more)
Growth increments in live wood: about 55
Height of trunk cross section where measurements taken: 2'
Area of discolored reaction wood at 2' cross section: 370 sq. in.
Area of white punk wood: 64 sq. in.
Total cross sectional trunk area at 2': 1,018 sq. in.
Width of alive, unstained wood: 4" to 8" (average about 6")
"Sound live wood" = wood outside the reaction zone barrier, represented by about 55 growth increments; it was intact only about 2/3 of trunk circumference.
Percent of "sound live wood" (compared to total area of trunk cross section): 38.2%

Observations
It was obvious over 20 years ago that damage had been done to the street side of this tree's base. At that time there was also an obvious cavity fill of cement at about 5'. The filled cavity was apparently the origin of a low large branch that was torn from the tree. The trunk had a noticeable swelling at this area. The decay column from the cement filled cavity did not extend to the trunk base, and it did not contribute in any apparent way to the decay found there. The tree may have been damaged during curb and gutter pan work, probably by large root severence after the tree was about 30 years old, maybe in the 1950's (calculating from reaction zone and annual rings). On the street side, there is a section of very small growth increments, representing declining reserves for a dozen or more years before adjacent cambium death. That section is about ten inches wide where the average thickness is about 2 inches. There is a transition area where increments gradually widen to that of the remaining live portion. The general vigor of the remaining portion of the tree seems to have remained fairly steady, with no noticeable reduction in width of growth increment up to the time of removal. Even with some trunk wood decay, there was no apparent danger of the trunk itself breaking, as the tree had successfully compartmentalized the decay there for many years. The main area of concern was with the supporting structure of roots below.
There was a 2" by 2" void at the trunk center at the 2' cross section, with what may be remnants of included bark or an old fracture across the core. This did not seem to significantly add to the basic problem. Also, for several years, Armillaria sp. mushrooms have appeared next to the trunk on the north side, between the flares of two buttress roots. This may be taken as a sign of decline and decay of some portion of the root system.



For the last few years bark sloughed off the dead portion of the trunk base, then ants appeared to be mining the wood there. Fungal fruiting structures became apparent over a year ago, and sections of punk wood began to break away. One of the remaining limbs nearest the street had a large internal decay column, with fungal fruiting structures visible along surface areas of necrosis.
There has been a progressive loss of branches, mainly on the street side, to the point where the remaining crown was weighted off-center and towards the north, away from the street.
Target area of likely tree failure: to the north, in the direction of prevailing winds, across the sidewalk onto the lawn southwest of Laxson Auditorium. Target area is used for special events, drawing hundreds of visitors who linger in the target area.


Conclusions
The tree may have been able to withstand collapse for a number of years longer, and was most likely to fail during a high wind event, when few people would be around. However, there is no way to predict what wind forces might bear upon the weighted lever of that tall tree during full leaf, with many people present and in danger. As there was no mitigating measure that could reverse or stop the advance of decay, decline, and death of tree supporting structure, it seemed wisest to eliminate the danger by tree removal. This was accomplished before the main event season for this area begins this year.
During the tree removal, while the trunk was limbless and about 15 feet high, a loader-tractor bucket was pressed against the trunk from the street side at about 8 feet high. With much less than full force, the tractor produced movement in the tree resulting in a lifting away from the curb of about an inch. This test seems to confirm the basic instability of the root system on that side of the tree, and the decision to remove it.

Reply to post by Mark Goodwin, on February 20, 2002 at 14:02:10:

Mark, it sounds like removing that maple was a tough thing to do. here are some reactions:

First, you collected good data for 2' high, but since the base was the bad area, measurements there will tell more about the tree's stability.
time to put on the big bar.

I've seen many times what you describe: reaction wood that is still solid and supportive, but who knows how alive it is. main thing is, it's strong. Drills, resistographs, etc. may perceive it as wood, not rot. Many arborists would say this wood would eventually decay so it can't be trusted, but to me that's not the point--everything rots in time. Its functionn in the tree ius more important than if the cells are alive or dead; that's a tough thing to measure, anyway.

You rightly suspect main defect was roots--weren't they investigated? If you don't have an air spade, a shovel and a water hose will expose the big roots. they can be sounded with a mallet and the hollow-sounding ones can be drilled if you need a more precise measure of decay.

Was armillaria and other fungi ID'd? Schwarze's "Fungal Strategies of Wood Decay in Trees" will tell you a lot about how trees rot, if you KNOW what you're dealing with. What kind of ants are "mining"? Carpenter ants are known to spread decay, other ants don't "mine" in solid wood, whether live or reaction wood. Ants are easy to treat, as insects go.

Was the non-street, heavy side of the tree, or the top, reduced to balance the tree? the push by the tractor is not a compelling measure of strength for me.

thanks for sharing your experience. I relearned that maples are ring-porous. A cautious lawyer may have cut the tree down ten years ago. A preservationist might have taken the above steps in an effort to save the tree.

Write back when you make the basal cut and measurements, OK? I'd like to use the information, if I may.

Reply to post by Guy Meilleur , on February 20, 2002 at 14:02:10:

The site linked in this post refers to Acer saccharum as a diffuse-porous species.

I have done a bit of excavating and autopsy sawing on part of the tree base. I'm not done yet.
So far I have found many reaction zones that had successfully stopped decay by white rot fungi.
One large buttress root had only the back and under sides still alive, but live roots of size were diving downward from it, and a dark band marked the barrier put up against the spread of decay.
I think it may take a look at the very underside of the trunk/root base to tell how much live rooting might be below the decayed portion.
So far if doesn't look likely along the edge of the curb.
By the way, my sleuthing led to an observation that the cement finishing work along the curb shows different tool marks, indication a replacement curb at some point in time.
The sidewalk also shows signs of replacement.
The curb and gutter pan are sinking, most notably adjacent to the softest areas of decay on the tree base.
I guess that may suggest decay below grade, causing a void for the concrete to sink into. (Or maybe it's something else?)
I will post more, later.

Reply to post by Mark Goodwin, on February 20, 2002 at 22:45:25:

Mark, thanks for those details, especially about the tree's successful defense against white-rot advance, in places.

Schwarze's Fungal Strategies of Wood Decay in Trees might help explain a lot of what you're finding, if you have the time to delve into it.

Digital pix of these sections w reaction lines/codit walls, and perhaps of fungi fruiting bodies for positive ID, would be extremely useful. If there's some way I can compensate you for your time, or help from afar (sounds like you're a long way from NC) let me know.

Re ring-porosity, I jumped to an assumption based on the pattern of dieback you reported. My goof. Visiting the whole porosity issue as it relates to tree defenses might be really instructive at some point. For now, the autopsy presents a rare opportunity to evaluate our evaluations of hazard in trees with root disease.

So many valuable trees get cut with so little evaluation, much less than it sounds like you put in before cutting; your work might help us--and them--a great deal in the future.

Reply to post by Guy, on February 22, 2002 at 15:49:38:

Guy -
the topic of porosity:

When I looked closely in my lab at movement beyond codit response I saw what appeared to be perforations in each vascular cell - wilt became successful at growing hyphea that found these perforations and extended itself out beyond cell walls and could move around the tylosis response of plugging - both above the obstruction and below and could resume it's onward growth. The black oak group shares all these built-in weaknesses in their vascular structures, the purpose I'm believing, is for water movement in spite of obstruction whether it be injury or pathogen related.

As far as "ring" imperviousness, this phenomena may be what allows staining beyond compartments. Hyphal growth is one of the characteristics of wilt and I believe it didn't display this feature pre-treatment in the early 1980's. The tylosis response in these hardwoods here I feel was effective enough to deny pathogenic responses in this fungus, the trees being able to digest the fungi enzymatically. It seems to me that early attempts to suppress the slow-growing morbidity of wilt chemically with sterol-inhibiting fungistats allowed eventually a "learned" response, a mutation in it's ability to develope a degree of protection.

Translocation of disease keeps me interested because the big boys are still keeping busy doing two things only - one: to mutate a variant specie host that resists wilt or other vascular fungi (a long wait indeed), or two: find the silver bullet that kills the disease without killing the host.

To close off these perforations is a road of thought - to perhaps change the surface tension of a viscous compound provided to the tree and assure it's uptake efficiently adaquate to locate throughout the vascular system. My stumbling block is should I concentrate on mutation of the disease back to it's early properties or stimulate a mutation of the host response?

Reply to post by Guy, on February 22, 2002 at 15:49:38:


I cut off another foot of the stump today. I did it in sections, taking pictures along the way. I do not have a digital camera, and it will be awhile yet before I have the film developed. I might decide to have a digitized picture disc made, but I am not experienced yet with handling digitized images. However, I am willing to share the images, if they turn out. I have a bit more saw sectioning I want to do before we put a stump grinder to work.

Hopefully, the photos will show evidence of tree defensive history, as well as help answer the question about the accuracy of my earlier conclusions. Also, I haven't yet seen clear evidence of curbside root cutting. There root crown is like a "blob".

So far, there seems to be a widening hollow directly under the middle of the trunk, connected with the small center void that I described at the two foot section. It goes down below soil grade, but I haven't probed or measured it yet. I'll probably try to make it more visible by cutting, and then photograph the extent of decay and hollow.

Also, when I excavated the roots along the curb, I found evidence of dead and decayed major roots, overlaid by damaged, partially alive roots. There were also a few newer, smaller roots (1/2 to 1 inch) that appeared to be re-colonizing the area.

I expect that I'll find very little, if any roots of size still alive and anchoring the tree directly under the trunk and along most of the curb side. However, I am still not clear about an analytic method for measuring/determining the actual anchoring potential that was there.

I think, from what I've seen of the roots so far, that the tree would not likely have fallen this year without a significant wind event. Rather than heaving over at the roots, I'm thinking that the point of failure would more probably have been a trunk failure, following several years of continuing branch decline. The thing which originally drew my concern was the apparent acceleration of the decay along the curb side of the butt (with fungus visible), as well as dead portions of buttress root tops.

One thing I did not do, but the opportunity is now gone, was to examine for decay inside the cement-filled trunk section (slightly above BH). I didn't want to risk tool damage. I may have been able to wedge it open lengthwise. Oh, well!

Pockets of soil and even some gravel became engulfed in layers of growth in the root crown (maybe six inches above the curb top). I'm still puzzling that.

I took photos (already developed) of the fruiting bodies of the fungus associated with the areas of white rot, but I haven't got a positive I.D. But the Armillaria mushrooms from the "better" side of the tree are well-known here. A scraping of the buttress roots next to the ORF revealed pinkish tissue fading to drier brownish tissue going downward. There was no bark separation there, nor visible white mycelium. However there was such evidence on thoroughly dead sections of root near the curb side.

Much of the dead butt-wood is a light brown inside and still fairly hard, almost like black walnut, even though there is evidence of insect mining. I found a pocket of black beetles about 3/4 inch long (not yet identified, but very limited anyway).

A website I visited today described Sugar Maple wood (read: dead and dry, for woodworking) as being non-resistent to decay. I guess if that's true, then this tree must have had some fairly good protective mechanisms to hold off decay as long as it did.

Which raises, for me, the question: How could I have done a thorough investigation and analysis of this tree without compromising the C.O.D.I.T. boundaries? Excavation would have been quite difficult along the curb, as the tree had grown over the curb, right up to the outside edge. And taking away dead, decaying wood, while looking for more hidden flaws, I may have hastened the spread of decay. And I would have been left where I am, still looking for a way to measure the potential strength or loss thereof. Matheny and Clark seem to focus on measuring voids and rot vs. sound tissue. I don't know how I would have done that satisfactorily in this case. Perhaps I could have eroded the soil out from beneath the trunk from the sides. I think that would have made me nervous: to be potentially destabilizing a tree I suspected of instability. (Did I mention the delays and other problems (like maintaining safety work zones) of working during school hours at a state college campus?)

Something I hope to learn: better methods and techniques for examining the root condition of suspect trees, esp. where the trees are located in difficult places (and avoiding making the situation worse).

More, later. (ha ha)

Reply to post by Mark Goodwin, on February 25, 2002 at 08:33:38:

mark, some responses to your dissection:

"smaller roots re-colonizing the area"--common for older trees to digest themselves and grow a new generation of tissue. I've seen roots grow into decayed trunks well above ground.

"soil and gravel engulfed"--anything packed against a spreading trunk can get engulfed, if it's pressed up there hard enough.

what is an ORF?

"taking away dead and decaying wood...hastening the spread..."--now here's a controversial area. digging out rotten wood exposes the infected area to air and light, which retard the spread of infection, right?. On the other hand, that rot keeps the inner wood from cracking, which could expand the infection court.

As long as boundaries are not broken, I think excavation is overall the right thing to do. Others have argued to the contrary, and the discussion goes on. I just think it's better to err on the side of discovery.

The bigger question that you raise is, how is the strength of "reaction wood" measured. Yes, it is reacting to decay organisms and may thereby be weakened, and forecast to be weaker yet as decay advances. But the reaction process also can make the wood stronger, and what if the decay does not advance?

While excavating, I stop at solid wood, and count it as "live" wood when applying the strength loss formulas. (My limited use of the Resistograph tells me reaction wood is measured as solid, same as living. Will sonic tomography see it differently? My guess is, not.) At that point I look at the top of the tree to find ways windsail can be reduced.

Taking soil from beneath the trunk is a touchy affair, but as long as roots are not lost and the soil it is returned, you haven't destabilized the tree further. An air spade is the ideal tool for that. If you have room in your budget for that, and advanced decay detection equipment (wish I did), you can refine your future diagnoses a great deal.

One active approach to tree risk is to invigorate the root system to increase defenses, prune to reduce sail effect (keep "damping" branches), and clean out and monitor decay. This works for me and my customers in most places. But I can appreciate the risk of maintaining such a public tree that people walk under all the time.

Reply to post by Guy, on February 25, 2002 at 23:03:42:

ORF is short for "oak root fungus", a common name for Armillaria hereabouts.

How solid is solid? What are your favorite tools for decay excavation?

With a few more cuts today, I exposed the cavity beneath the butt.It seemed to follow the shape of the original root system of the tree, that is, it made a transition from downward to outward.
There was a hollow directly beneath the trunk down below the grade of the gutter pan surface. The hollow extended at least three feet wide at the bottom.
There was no "tap root".
Spread your thumb and fingers as wide as you can, put them on a table, holding with your palm raised above the table. That is a pretty good approximation of the trunk, root crown, and live buttress roots at the surface. The space under your palm and the space between pinky and thumb on your wrist side represent the missing root system.

On the subject of reducing wind sail or balancing the load in the canopy:
1.) I don't think it would have helped this tree to take away any food making capacity, unless the part was at the stage where it was in danger of becoming detached. I think the tree was already losing the battle between growth and decay.
2.) There was hardly any major horizontal growth to remove, and few choices for reduction that made any sense to me. It would have looked quite butchered, and hastened to decline even more. I would rather have left it alone, except for dead wood cleaning.

Five or more years ago I removed the only limb of size over the street side. It was feeding the adjacent side of the tree. It had a large area of missing bark and dead wood exposed along the top, and it was just a couple of feet above bus roofs.
Well, I decided then to remove it, without probing for depth of decay (most maples here are soft maples, and all decay is significant in them). But when the limb (about 8") was cut, the decay was compartmentalized, and the wood was very strong still.
I believe the removal of that limb hastened the progress of death and decay at the tree base. So, conservative approach to removal of any live parts, especially in an already wounded tree, seems in order.

I notice that Matheny and Clark list of trees' inherent failure patterns gives
Acer saccharum a relatively low rate of failure, saying it declines before it fails, with some trunk failures due to stem cankers (e.g. Eutypella sp.); or as medium hazard due to failure of poorly attached branches.
This tree had no visible trunk decay above the root crown (although it had a cement filled cavity), and no obvious problems with branch attachment. But it did have a canopy in decline.

Reply to post by Reed, on February 25, 2002 at 08:33:38:

Reed, those perforations in in cell wall you're seeing are also described by Schwarze in Fungal Strategies...: "there are numerous indications for deviations from the general cell-wall structure in the form of radial structures in the S2 layer...the path of least resistance for the fungus." page 20. He speaks of ectoenzymes and microfibrils acting in advance of hyphae.

the first loose $60. you need to spend on this book if you want to know about fungal strategies. I've had to reread sections because it was too much to take in the first time through, but it's well worth it if you're interested in this kind of thing.

Ceratocystis is not covered specifically in this book but French ('91) said of it "Once inside the tree, the fungus can spread rapidly through the vascular system in red oaks." page 98. I only know wilt from removing victims in the late '70's in WI, but I saw nothing slow about it. So I'm not sure how slowly the disease acted before treatment in TX or if it's mutated.

Your question is a good one; I don't know enough yet to venture a guess. It's a difficult but fascinating study.