what percentage of a tree's roots are in the upper nine inches of the soil or ground line? I need some documentation and references. Thanks. The more information I have on this subject, the better. Thanks. WAG

Reply to post by will gates, on February 15, 2000 at 01:18:48:

Dr. Phil Wargo from the forest service lab in Hamden, CT just gave a presentation at the Penn-Del ISA conference and showed some graphs of root depths which support your question.

Reply to post by will gates, on February 15, 2000 at 01:18:48:

Will,

i am sure that there is no set answer. In general the majority of roots are but the
exact percentages will be determined by a number of factors including genetics, soil
structure and bulk density, irrigation, and environmental conditions.

Mark

Reply to post by Scott Cullen, on February 15, 2000 at 01:18:48:

Will.
Whilst both comments from the earlier postings are surely correct, it is of note and interest that I have just returned from a 10 day working trip through France where there has been absolute tree devastation. This catastrophe, over 360 million trees blown down,occurred as a result of wind speeds in excess of 135mph. I was as a result able to inspect many, many exposed root plates of all shapes, sizes and depths. Though was no correlation except to the local micro climate and geological conditions, which of course were very varied. Some of my photographs show the tipped over root plates of mature 60ft+ high Pinus radiata, that are restricted to 6ft diameter and only 3inch depths. And yet until the most recent of storms they had happily survived for many decades.

Colin

Reply to post by will gates, on February 15, 2000 at 01:18:48:

I have seen Douglas-fir rooted to depths of:
6 to 9 inches. That would mean from 0% to 100%, depending on several billion factors.

Reply to post by Peter Torres, on February 15, 2000 at 01:18:48:

I have also measured Douglas-fir roots to a depth of eleven and a half feet. That's where the several billion comes in.

Reply to post by Colin Bashford, on February 15, 2000 at 05:26:56:


" Some of my photographs show the tipped over root plates of mature 60ft+ high Pinus radiata, that are restricted to 6ft diameter and only 3inch depths. And yet until the most recent of storms they had happily survived for many decades."


That sort of presents a pickledicklement for Mattheck's structural explanations. Once again, Mother Nature teaches us humility when she stretches.


Bob Wulkowicz

Reply to post by Wulkowicz, on February 17, 2000 at 16:43:00:

Yes it certainly does. I was about to ask Colin how these observations might relate to CM's 'critical root plate,' but you beat me to it. This storm certainly seems like extraordinary loading. It would be equally interesting to know the proportion of trees with root plates bigger than "critical" also failed.

Sounds like the making of at least one fascinating article Colin.

Reply to post by Scott , on February 18, 2000 at 16:52:13:

Bob, Scott.

I am not sure that a small root plate on a standing tree is in any way a problem for
Mattheck. He states that at less than 3m there is a distict increse. He does not say
it will fail.

The size of the root plate in relation to tree height, canopy width, shape and area
would cetainly be valuable in understanding extreeme forces on trees.

Mark

Reply to post by Mark Hartley, on February 18, 2000 at 22:16:30:

Guys. I am attempting to get my head round all sorts of issues that include those that you have rightly mentioned. There is much to consider from my observations and notes and I ned to compare this data with the experience gained as our Central Government tree expert on their Technical Committee that reported in a similar vein on the effects of our Great Storm of 1987. The effects of the extreme force of the gales in France (130+mph winds) as shown in some areas does not make sense to the relatively low level of damage as noted in immediately adjacent areas. The symptoms of damage which provide early confusion are not necessarily restricted to trees. For instance there are many examples of signage with I section sound steel posts of around 4" thickness/size with relatively small in area signs, say 30" square; blown over so that the signs are now horizontal to the ground and yet immediatley adjacent to these are larger in area signs on smaller dimension posts that are apparently undamaged. In some cases the damaged signs are at a lower level than the undamaged and in other examples they are taller.

In simple terms to a tree man the effects some 6 weeks on from the storm are devastating and depressing and of course the extent of the damage will not be apparent for sveral months yet. I am already instructed to make followup visits, inspections and appraisals starting in early summer when new symptoms that confirm damage may well become apparent on trees that at present do not necessarily show the damage sustained. Yes I am sure that there will be many articles to follow of which my experiences and observations will be but a small part, for so widespread is the damage.

Colin

Reply to post by Colin Bashford, on February 19, 2000 at 21:45:32:

With reference to my last posting I should make it clear that the sign posts were not just blown over to lie flat on the ground but that the stell/iron posts were bent at right angle through 90degrees to be horizontal with the ground. The signs were not hit by falling trees and bent in that manner.

Colin

Reply to post by Colin Bashford, on February 21, 2000 at 17:32:53:

I am not a meteorologist, but it occurs to me that some kind of wind shear may have occured, with locally intense down-bursts or pockets of turbulence.
Just as tornadoes appear to skip about sometimes, it seems that other turbulance might have locally different effects.
Do you know at what altitudes the wind speed measurements were taken?
Was the ground level air relatively cold and still, with a warmer and faster layer above?

Reply to post by Colin Bashford, on February 19, 2000 at 21:45:32:

Similar events are seem following tornados, where one object is severely damaged, yet something seemingly less sturdy a few feet away is untouched. A few years back we had a minor tornado in the area that destroyed a high school gymnasium. Only one wall was left standing, and the award pennants hanging on it were still in place afterward.

We're looking here at turbulent fluid mechanics. The eddies and currents that make up the air flow are chaotic, and rapidly changing. We know that an object will fail when its load in any particular direction is exceeded, even momentarily. A minor defect or even harmonic motions can cause the limit to be exceeded at one object but not for a similar object a short distance away. Steel posts are not all the same, and stress loads are not always even supported in all directions. The sail effect of a small sign might exceed that of a larger sign depending on something as simple as the direction the signs are twisted at the moment the high forces strike it. One sign might be pulled over, the other might just twist back in another direction.

Or maybe it just depends on some butterfly in the Amazon basin.

Reply to post by will gates, on February 15, 2000 at 01:18:48:

The challange in determining at what depth roots will potentially grow is actually a soil condition/species adaptation exercise. Root will proliferate where the resources of life exist (oxygen and water) within the limits of the species requirements. Therefore the question is more, "what are the requirements and limits for gasious exchange and moisture for my given species, and where in that range does the growing site fall".

Regarding rootplate and tipping, the rootplate is only one factor to be sure. Soil shear strength, cohesion, and the adhesion of soil particles to long rope-like roots are all involved in developing the windthrow model. Has there been any work done related to arboriculture in the specific area of soil mechanics? Since we build things all over the place it should be a well developed sciance, but the mechanics of a tree on and in the soil may be different then a building with footers or friction piles.

Wayne

Reply to post by Mark Goodwin, on February 21, 2000 at 17:38:46:

Mark, I have yet to find out heights at which wind speeds were recorded.

Reply to post by Russ Carlson, on February 21, 2000 at 17:32:53:

Thanks Russ! I might even go for the butterfy option!

Reply to post by Russ Carlson, on February 21, 2000 at 17:32:53:

There are many references to the seeming contradictions in damage. The one that comes to mind is from the excavations at Pompei (spelling? you know the Roman city buried by the volcano). Stone columns and the like shattered, while delicate glassware or pottery was recovered intact.

Reply to post by Scott Cullen, on February 22, 2000 at 22:05:45:

It would seem almost easier to explain the differences between columns and glass jars, Scott. Pompeii was buried in ash- very fine particles falling from above. Like snow, it builds up deep layers, and larger objects will have to bear a heavier load. They will eventually reach the failure point. A smaller object like a glass jar has less surface area, supports less weight overall. Also, once the object is fully buried, the additional load from above becomes distributed better, not pressing straight down only on the matter directly beneath. (This is why your corn flakes are flakes and not dust in the box.) A small object wwould have been quickly buried, and thereby protected somewhat from the greater pressures that larger, exposed objects might bear.

Reply to post by Peter Torres, on February 18, 2000 at 02:50:56:

I think Peter has touched on the key point in this thread. There are so mnay permutations that to extract a few salient points and use them as surrogates for future predictions may be impossible. Some years ago (well decades actually) I was involved in analysing point plume discharges from tall buildings using fluid mechanics modelling. The results amazed me because there were so many areas where the air was still and in fact the fumes sat in an almost steady state while all around the air was turbulent. We see the same idea in streams where water eddies at certain points but only in certain water level conditions. Wind is just another fluid and all fluids have extremely variable conditions from point to point especially when the surface across which, or through which they are flowing is highly variable. In effect, there will be macro and micro variations at any one locale, which is why the degree and exctent of damage will always be so variable. Another compounding factor is that strong winds not only flow fast, but have pulses of energy at macro and micro scales so any one obstacle in the path of the wind experiences an almost infinite variety of stresses and strains.

Please keep us posted Colin. It will be interesting to see what you all come up with.

Julian

Reply to post by Julian Dunster, on February 18, 2000 at 02:52:56:

To all - boy! this seems to have stirred up a wealth of experience and a further range of variables. Yes I am still working on thr data obtained and yes Julian I will keep the knothole up to date. I of course accept the effect of other nearby physical factors and have looked for influences that may have caused varied wind turbulences and vortices, albeit they would have to be in very close proximity to each other. Many of the sites of specific but very limited damage not necessarily associated with trees were in generally wide open spaces. It has long been my view, along with others that such winds as associated with cyclonic, tornado or whirlwind actions, i.e. that they are twisting rapidly; skip along like the action of a fast twisting toy top. When they hit objects or variances in ground form they jump and skip to one side or lift up to a higher level. I understand the climatic forces involved and although not qualified in meterology do not necessarily find the answers to the questions posed therein. The toy spinning top format does meet a lot of the factors noted on site. Could the cause of the variation in the damage noted be that simple?? I am still looking and welcome all your expert opinion. On the Pompeii front Russ is I am sure right. The first effect of the eruption was the fall out of fine ash which not only quickly covered all small objects but filled such as glasses and vases making them more resistant to the pressures of lava flows and increased volcanic fallout which followed. At that st age I suspect the pillars/columns etc were in the path of the outflow and were pushed over.

Colin

Reply to post by Russ Carlson, on February 26, 2000 at 05:33:12:

Well, I'm not entirely sure the additve weight thing explains it, but certainly if the ash filled the delicate vessel the wieght above would be distibuted right through the vessell to the material below. Good observation.

Reply to post by will gates, on February 15, 2000 at 01:18:48:

I hope you guys are still following this thread. What experiences - or second had information - do any of you have with tree anchoring in addition to the surface root plate? This might be what is traditionally described as a "tap root" in the ttrue - if uncommon - sense of deep roots searching for moisture or a structure that's more a deep mass of wood below the stump that might extend below the plane of the butress or compression roots.

I've seen it in ash stumps I've struggled to remove --- those are the ones I happen to recollect.

It seems anomolous, but maybe that's in part because we're accustomed to seeing the shallow ones that do topple.

Any ideas on frequency, species characteristics or loading or environmental factors that might be involved?

TIA

Reply to post by Scott, on February 15, 2000 at 01:18:48:

Scott -- a couple of thoughts:
1) There is an Arboricultural Journal article of 10 years ago or so that reported the results of a survey of species root structure differences in upturned trees after an English hurricane. Their numbers were something like 80% plate root structure, 18% heartroot structure (like red oak), and 2% true taproot structure.
2) Also, soil air makes a big difference in my experience. Shagbark hickories, for instance, put down a significant taproot on upland sites, but on riverbottom sites where they are also common, there is usually no taproot at all.
3) And the recent work on "hydraulic lift" in sugar maples show that this species is bringing up water from 30-50' below ground.
Fun stuff!

Reply to post by Jerry Bond, on March 01, 2000 at 06:35:30:

Jerry, thanks for the prompt reply.

RE: 1, is "heartroot" a recognized characteristic or concept or just a desriptive term? I'll have to go through some of the other recent threads.... Colin did you post that you were involved in assembling some of that UK hurricane data?

RE: 3, I had forgotten about the "hyraulic lift" concept, but recall reading some of the stuff out of Cornell some years back.

Thanks again.

Reply to post by Scott, on March 01, 2000 at 10:45:20:

Scott Yes I have that dubious honour. But see also my reply to your personal posting. Colin