longer cuts on poor compartmentalizers| CODIT WALL4

Sean Freeman

Okay, I've been sitting here very late at night/early morn reading what people have posted and the various positions put forward, I have very carefully reread what I posted as well as everyone else, I have reread my favourite sections of A Shigo "A New Tree Biology" and hope I can offer something of a solution to what seems at face value to be an impass re the presence or not of wall 4 across the face of wounds that never (or have not yet) occluded.

As has been said by a number of others it comes down definitions and getting tied up in semantics......Let me give you some quotes...

"The CODIT model has 2 parts: I; walls, 1, 2 and wall 3; II; wall 4. Wall is a model term and should not be identified too closely with chemical and anatomical terms....walls 1, 2 and 3 are model representations of the reaction zone. The reaction zone is a continuous boundary about the developing column of infected wood. The walls help to identify the 3D nature of the column. the reaction zone is the chemical strengthening of existing boundaries
Part II is represented by wall 4, which is the barrier zone. The barrier zone forms after wounding. the cambium forms cells that differentiate to form the barrier zone" (p46 A New Tree Biology)

The italics are Shigo's emphasis the bold mine.

So it would seem by this little quote Eric has the points...except for the fact the Shigo is adamant that we should not be thinking of this model as a rigid blue print to be overlaid ever tree we encounter, its a model of the structures and processes not the physical reality...but we're not done yet...oh no not by a looooong mark!

Just remember that in all the following quotes Shigo uses the term barrier zone and wall 4 as interchangable terms.

"What happens to the wood inside the boundaries will be determined by many factors. Trying to assign one term or name for the process is like trying to give one colour for the rainbow. We need terms like rainbow or terms that will imply changes over time. Living systems do not stand still." (p311 A New Tree Biology)

Again cautioning against the religeous application of a model onto the emmense variations in nature.

"If I had to name one, and only one factor that has caused more confusion throughout the research history of trees than any other factor, I should name the study of the cross section alone." (p323 ANTB)

We all need to be aware that the radial cross section is what Shigo often referred to as an "artifact"

In a diagram that Eric used earlier in the thread he highlighted the orange line in the new growth as wall 4, but the diagram clearly states that the orange depiction (not reality, a model) is both wall 4 and barrier zone.



The diagram depicts the barrier zone being present..formed in the tissues of the open wound...this is not very helpful, somewhat confusing perhaps unless you recognise that even though wood tissues may be critically compromised functionally they are still capable of alteration as part of the defensive response by the tree....from my post #50 Eric does recognise this and has said stated this in his own posts in this thread. I think many of us are guilty of skimming much of the literature (I know I am!!!) and this can result in confusion in our own minds when coming to grips with specific applications of a model to a very complex physical reality in the tree.

"I am getting concerned that tree people with spial interests may begin to skip over material they feel is not germane to their needs. I hope you will not do this. I caution you against this, because the points I keep trying to make all focus on the tree and how it manages to survive against an unending number of agents and pathogens that try to outwit the tree." (p387 ANTB)

"As cells are injured and die, their cell contents come into contact with the air. Chemicals in the cell react with the oxygen and these new compounds are usually antimicrobial-inhibitors-and they cannot (for the most part) be broken down by the inading organisms. Yet some pioneers can grow into the tree against the antimicrobial compounds. Some pioneers have developed unique ways to digest the defense compounds. Other organisms fight fire with fire they alter the trees compounds in such a way that make the compounds not harmful" (p121 ANTB)

What we end up seeing in the dissected tree is often the manifestation of this complex interaction between pioneers and tree, and can be very hard to definitavely decipher.

"A new growth ring has yet to form so there is no barrier zone" (p120 ANTB)

For those that disagree I'm sorry but for Shigo the barrier zone he describes yes has a relationship to the wood tissues at the time of wounding (of course) but is not formed in those tissues...other kinds of barriers are......the barrier zone/wall 4 is formed in the new growth after wounding, ther is little confusion here.

I leave the last words from me on wall 4 and the barrier zone to Alex Shigo

"When the cambial zone about the wound resumes growth, the newly formed cells differentiate to form a boundary that seperates the wood present at the time of injury from new wood that will form after the boundary is completed. That seperating boundary is called the barrier zone." (p599 ANTB)

Attached Images

coditwall4sketch2.JPG (41.2 KB, 102 views)

__________________
Sean

Trees are poems that earth writes upon the sky,
We fell them down and turn them into paper,
That we may record our emptiness.
- Kahlil Gibran

Ekka

Sean, see in this pic where I circled "none here though", I wonder what the white is?

__________________

Free Tree and Green Industry Link Directory

Qualified Brisbane Tree Lopping | Stump Grinding and Stump Removal Brisbane

Brisbane Tree Care, Consultations, Developer, Tree and Arborist Reports

Forum Sponsors

Sean Freeman

The colours in that diagram are most unhelpful...clearly the intention is to show decay behind the white face of the injury...but the difference between the brown and orange is almost impossible for me to detect!

So please disregard my inclusion of the diagram have only succeeded in further muddying the waters there! My second blue arrow is pointing at what the original author intended to be seen as decay (brown colour)of that I'm pretty sure not barrier zone (orange colour)...sorry everyone for that!!!

Irrespective of the diagram and my tangent, Shigo's description of what he meant by wall 4/barrier zone is clear.

__________________
Sean

Trees are poems that earth writes upon the sky,
We fell them down and turn them into paper,
That we may record our emptiness.
- Kahlil Gibran

Ekka

Yeah, clear to me to, what's all the HooHaa about then.

__________________

Free Tree and Green Industry Link Directory

Qualified Brisbane Tree Lopping | Stump Grinding and Stump Removal Brisbane

Brisbane Tree Care, Consultations, Developer, Tree and Arborist Reports

Forum Sponsors

Sean Freeman

I think the hooha you describe is from confusion about the meaning each poster is taking from the terms used.

__________________
Sean

Trees are poems that earth writes upon the sky,
We fell them down and turn them into paper,
That we may record our emptiness.
- Kahlil Gibran

Ekka

Arborcraft started it, opened a can of worms and nicked off!

__________________

Free Tree and Green Industry Link Directory

Qualified Brisbane Tree Lopping | Stump Grinding and Stump Removal Brisbane

Brisbane Tree Care, Consultations, Developer, Tree and Arborist Reports

Forum Sponsors

Sean Freeman

Hmmm some people have issues they can't escape from I guess

__________________
Sean

Trees are poems that earth writes upon the sky,
We fell them down and turn them into paper,
That we may record our emptiness.
- Kahlil Gibran

newguy18

D and S mc here is a work by Shigo showing what Ekka has been saying all along is accurate.
http://www.huhs.org/departments/agri...sign/codit.pdf

__________________
Have your say join us today.
http://www.youtube.com/watch?v=Xzkd_m4ivmc
http://www.youtube.com/watch?v=Xzfzb...eature=related
http://www.youtube.com/watch?v=x-OqK...eature=related

D Mc

New Guy, thanks for posting that. Truthfully, I was not going to make any further posts on this thread because it seemed so pointless. But because you made an honest attempt to inform me I will return the gesture. I never finished school so my formal education sucks but I have been working in trees for 40 years. During that time I have managed to learn a few things.

There were no wrong statements made in our previous posts. If you will go to Post #74, click on the Tree Decay pdf, please note the author is Shigo. To understand this subject, please read the entire pdf. However, at least go to Patterns of Compartmentalization and Successions, (found in the Table of Comments) find figures 40 and 41. Both of these plates show injuries that did not seal, yet Wall 4 is shown. So I can say with confidence that Wall 4 will do it's thing whether the wound seals or not.

Next follow the path of the red marker for Wall 4 and notice just how far beyond, above, below and around the circumference of the tree it has spread. This did not happen in the blink of an eye but took quite some time. During the time before the farther most cells changed to Wall 4, they were functioning as normal cells, so I can say with confidence, Wall 4 does not require callus growth to exist. But without looking at the entire tree, these comments might not have made sense.

If I ripped off a leaf from a tree and held it in front of you and said, Look trees are green! You would say no; but I woudl say, I have proof! Is not this leaf green? You say yes, the leaf is green. But the entire tree is made of many colors. I would then say, yes indeed.

When I read Sean's quote from Alex Shigo's A New Tree Biology, it almost made me cry and thought it was worth repeating. I will put part of it here:

"I am getting concerned that tree people with special interests may begin to skip over material they feel is not germane to their needs. I hope you will not do this, I caution you against this..."

D and S Mc

Ekka

The diagrams only show wall4 where there is new cells, it is derived from new cells. Whether the new wood growth seals the entire surface or not is irrelevant, fact is the wall4 cells are part of that growth.

It spreads in the vertical plane because the tree grows outwards in the vertical plane too, it's a big cylinder.

Again, where there is no new growth there is no wall4.

__________________

Free Tree and Green Industry Link Directory

Qualified Brisbane Tree Lopping | Stump Grinding and Stump Removal Brisbane

Brisbane Tree Care, Consultations, Developer, Tree and Arborist Reports

Forum Sponsors

fosheezy

wow what a thread. the way i understand wall 4 is (*suck in a deep breath*);
-the cambium grows putting xylem cells on the inside and phloem on the outside as per usual. trunk is expanding. tree is happy.
-tree is wounded.
-instead of putting another layer of unprotected xylem on the inside a heavily suberised layer of cells are laid down (suberin is the same waterproof and inpenatrable substance in bark that stops infection from the outside).
-bam, barrier zone is laid down and cambium goes back to producing xylem.
-if walls 1,2, and 3 are all breached; so be it, all the new wood is protected by an 'inner bark'.
-tree is happy again (although has lost significant storage capacity)

-and woundwood grows to close the wound re-instating the surface area for which the cambium can pruduce tissue, but does not compartmentalize decay (all walls have already been laid down). and yes, when the wound is closed there will be very little oxygen for decay, but that does not mean zero oxygen! if oxygen could not get through wood there would be no living cells within it when we all know rays are living cells.

whateva', peace out hombre's.
anton.

Ekka

There was a document with pictures that showed what is layed down is a bunch of cells that then change to the various components, but the inner cells against the wound are similar to what you say. So imagine a wad of cells 10 deep for example are laid down, the inner couple become the wall, the middle the xylem/phloem etc and the outside periderm.

So I dont think that the cells laid down are suberized but normal then converted to suberized ... documentation suggest that.... but you are most welcome to add any reference to this as you can, best is microscope evidence etc from reputable places like uni's etc.

I was researching decay colonization after wounding gymnosperms vs angiosperms the other day and that dug up some interesting similar stuff too. Gymnosperms are actually superior in their defence to decay due to the volume of tracheids they have over angiosperms.

__________________

Free Tree and Green Industry Link Directory

Qualified Brisbane Tree Lopping | Stump Grinding and Stump Removal Brisbane

Brisbane Tree Care, Consultations, Developer, Tree and Arborist Reports

Forum Sponsors

fosheezy

nah not quite like that in one big lump of cells, i think its a bit more structured; as one row of cells splits off onto the inside of the cambium they become either xylem or wall 4 depending on whatever the situation, but the normal course of phloem and periderm cell division (towards the outside of the cambium) and differentiation is uninterupted because its already on the outside of wall 4.

yep sorry, my bad because all new cells separate from meristematic cells as undifferentiated paranchyma

how do tracheids resist decay better than vessels?

Ekka