? Have a client that raised the grade six feet with
a sandy (beach sand like) soil. The soil was excavated
from the site. A retaining wall holds back the
sand and is twenty feet from a thirty inch red
Oak. With this species and soil type would you expect
any significant damage to the roots.

Reply to post by Andrew Wood-Gaines, on March 12, 2000 at 22:52:03:

Are you saying that the tree and a 20 ft. radius was untouched, but beyond that is built up with a 6 ft. depth of sand?

Reply to post by peter torres, on March 12, 2000 at 22:52:03:

Sorry Peter. i should reword the question.
On property A there is a 30 inch Red Oak. It is located approximately twenty feet from the fence line.
The nighbour on property B raised the grade along the fence line by six feet.
there is a retaining wall to hold back the soil
No roots were found in the building of the retaining wall which has a footing one foot deep.
the wall makes a tangent just inside the drip line. i m thinking sandy soil- Red Oak- deep tap root.
There cannot be a whole lot of roots near the retaining wall

Cheers
Andy

Reply to post by Andrew Wood-Gaines, on March 16, 2000 at 01:28:26:

Andrew, this is a perfect example to demonstrate my root loss database.

30" stem diameter
50' branch spread (I guessed at this)
20' distance to disturbance
expect medium root dieback from disturbance (3 years)

The dripline radius is 25 feet
Projected radius, based on 12" per inch of diameter, is 30 feet.

The results are as follows:

The Critical Root Zone, based on Mattheck's Root Plate Radius chart (Body Language of Trees, p95), is 10.4 feet. This was not compromised.

Dripline Projected
Live Root Distance 18.43' 17.79'
Root Loss Area 186 sq ft 456 sq ft
Total Root Area 1963 sq ft 2827 sq ft
Affected Root % 9% 16%
Actual Damaged % 7% 13%


Live Root Distance: The distance from center of stem to the edge of the live roots (including estimated root dieback).
Root Loss Area: Surface area affected by the injury, including root dieback.
Total Root Area: Total surface area or root system, based on dripline or projected distance.
Affected Root %: The percentage of the Total Root Area that is affected, including root dieback.
Actual Damaged %: The percentage of the Total Root Area that is directly impacted by the disturbance (does NOT include estimated root dieback).

You can select to use either the dripline as the basis for the estimate of root loss, or a projected root radius based on a factor you enter. Here I used 12 inches of radius per inch of stem diameter, but you could select some other factor.

Now, you have to take this information and digest it, apply your expertise, and determine if the damage is significant. But don't ignore your gut feelings.

Reply to post by Russ Carlson, on March 22, 2000 at 00:22:09:

In the previous post, I tried to make a small chart of the results. Apparently the message board software ignores long strings of spaces, so it was all condensed.

There should be 3 columns, the first is the label, the second is "Dripline" with the first set of numbers, and the third column is "Projected" with the second set of numbers.

Hope this helps. Refer to the screen shot, which shows the"Projected" numbers.

Reply to post by Russ Carlson, on March 22, 2000 at 00:22:09:

Russ,

1. Is your Critical Root Zone for structural stability or tree health?

2. I don't have B.L.O.T. Is the chart similar to the Root Radius (Rw) failure curves Mattheck et al present in "Failure Criteria for Trees," 1993, Figure 5 and "Field Guide for Visual Tree Assessment (VTA)," 1994, Figure 9?

Reply to post by Scott, on March 22, 2000 at 23:48:57:

1. Based on Mattheck's chart for structural stability against windthrow. Remember, this is nothing more than a guide to help you make a decision. It is not the decision maker- you are. It is only a GUIDE! (Lew, tell Scott what a guide is! [g])

2. This is the same chart.

Reply to post by Russ Carlson, on March 23, 2000 at 11:13:12:

Scott,

Per our Webmeisters' instruction;

A guide is a guide is a guide!

lew

Reply to post by Russ Carlson, on March 22, 2000 at 00:22:09:

That is really cool. There is a lot of info to digest here.
Whats the book by Mattheck "Design by Nature".
Scott seems to think a formula is pie in the sky
( PI in the sky) would be more appropro
for a tree formula)
formula is not so important as to the parameters
it represents. Using linear programming a set
of limits could be established which would give
some creedence to court evidence. Providing the
wisdom of experience is not left out.

One thing I question the 16% afffected area to cause
medium dieback. Are these values equatable.
what about regrowth,especially if it is not in the critical zone. Is dieback pertaining to the root\
system or to the tree.(direct relationship??)

Thanks Russ

PS I like your hair.

Reply to post by Andy Wood-Gaines, on March 22, 2000 at 23:48:57:

The root dieback amount (Moderate rating in this example) is the relative loss of roots you might expect to die back from the cut ends. IOW, if you cut a trench 20 feet from the tree, moderate dieback would kill about another two feet. This is derived from a ratio of trench distance to total root radius (yes it is somewhat arbitrary, but follows my own anecdotal investigations). But you can assign a value for it, for various conditions.

When cut, some roots will almost immediately resprout, with little dieback at all. In other cases, cut roots seem to not regenerate at all. Others suffer some degree of dieback, on average for that root system. This needs to be addressed in the model. What you get for results is a comparison between maximum expected dieback and none at all.

As you point out, a lot of judgement needs to be applied. A tool of any sort is useless without the knowledge on how to apply it. If I tell you a tree has a trunk diameter of 32 inches, is that a large tree or a small one? It would be very large if it is a Bradford Pear, but a rather small Sequoia. Experience must be applied along with the tool, if a proper determination is to be made.

Reply to post by Russ Carlson, on March 29, 2000 at 23:48:12:

I see. Is there any correlation between ability of the roots to regenerate with species that branches are able to regenerate. Is tenacity an genetic throughout

Reply to post by Andy Wood-Gaines, on April 01, 2000 at 00:42:40:

In this calculator I didn't include any factor for regeneration of roots. That is up to the arborist to determine at what rate they will grow. The calculator tells you what the loss is shortly after the damage (allowing for some dieback of the roots). Also, I figure the new roots that do grow out will not provide much stability or structural strength for a few years until they increase in size. They may provide substantially more physiological support, however.

Once again, a lot of interpretation and judgement must go along with this. But it helps quantify the concept of root loss, so you know some of the parameters.