Pruning cuts - collar, collarless and co-dominant

Eric Frei

At the roadside again having a look at some pruned trees. This is the same place where the two stumps were so most likely the same contractors.

I took some pics of their finishing cuts.

This was a great opportunity for the 3 standard cuts that pretty much dominate our industry. When all is said and done these 3 cuts are about all you need to know.

There are 3 types of branch unions.

Collar
Collar-less
Co-dominant

And that's it! Hence only 3 cuts, so how easy is life really when pruning? Sure some people will complicate it and say there's a cent-time cut where you leave 3mm of stub to compensate for rot, there's others that say there's a heading cut on a slight angle just above a node etc like you'd do with a pair of secateurs to roses. But in trees work this is pretty much it .... and in this example you'll see what they did.

However do remember that you should try to keep the cuts small, so do this before branches get big. Rule of thumb they reckon is 4" dia or 100mm dia in the metric scale.

Remember, we are talking about finishing cuts, some argue that you can leave a stub for a year ... return then whack it again, prepares the collar for more defences, but eventually after many reductions and returns you are going to end up making a finishing cut.

In the next bunch of pic's you'll see the red line where they should have cut it.

In the second to last pic have a look at the epicormics that have decided to grow due to the poor cut made.

Link to stumps at same location.
Road side stump cut analysis - Tree World

Collarless union




Collar




Extended Collar



Codominant

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jim1nz

If this deadwood was removed, the trees callus wood would have already occluded the wound.

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SPEED ALWAYS FOLLOWS TECHNIQUE

mdvaden

I've seen some oldery English Holly, crabapple and grand fir, where the branch collar of the lower limbs was from 2" to 6" out from the trunk, although that's not the norm.

l2edneck

that is a nasty cut in my book.I was always taught to do a 45 so water can run off and not give any chance to sit and rot.I imagine the redline is demonstrating proper cut?

Notahacker

It looks like those guys are all over the place when it comes to making a good collar cut. Inconsistent cuts? What's wrong with those guys?

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"Quality costs as much as it saves." My great uncle Simon Murphy

Sean Freeman

The photo you use is of a codominant union with one of the stems removed, and the red line does show the best line for the final cut, in the case of codominant stems. In pruning non codominant stems (I won't say normal because what does that mean?) the aim is to make the final cut just outside the branch collar at an angle that mirrors the branch bark ridge. I've put some diagrams in a doc attahced below

Idealised pruning angles.doc

The reason for the desire to make the final cut there is two fold, one you avoid cuting into tissue that are part of the stem, that would expose the tree to the high risk of insect/fungal pathogen colonisationof the stem...not good..two you leave the branch protection zone intact which inhances the chances of the tree quickly and effectively closing the wound very soon after the cut is made, less than an hour in some species (that is the chemical closure I'm talking about not the formation of callus tissue followed by woundwood which can take much longer)

The situatiion with codominants is more complicated because there is no branch protection zone, you are always going to be exposing stem tissues to oxygen ingress and subsequent dysfunction, the angle of the cut relates more to the attempt to reduce the epicormic growth response trying to clearly establish the remaining stem (no longer co-dominant) as the apical growing point. Its one of the hardest things to succeed with especially when the codominants have been allowed to reach the size they are in your photo. It is far better for all if they are pruned out when much smaller.

If I were the climber or bucket guy making the final cut I'll be honest my finishing cut would have been the blue line.



Mainly because it doesn't look like there is significant bark inclusion (at least on the side we can see) and I would want to reduce the surface area of wood tissue cut as much as possible, whilst reducing the likelihood of epicormic sprouts forming and perpetuating the hormonal confusion wiithin the tree as to which part is the leader.

The water thing is a bit of confusion it really isn't connected to the reasoning behind the angle of our final cut.

SF

Eric Frei

Here's the collar cut, they're in the pics in the first post.





Boa, surface area is a falacy, if Shigo were alive today he'd tell you the same. At a seminar Brett Hamlin asked Shigo if it would be better to take a shallower angle reducing the surface area ... Old Shigo gazed sternly and said that's not the case and suggested he read more of his books. lol

The bottom of the BBR is the guide.

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Eric Frei

Here's the collar cut, they're int he pics in the first post.



Boa, surface area is a falacy, if Shigo were alive today he'd tell you the same. At a seminar Brett Hamlin asked Shigo if it would be better to take a shallower angle reducing the surface area ... Old Shigo gazed sternly and said that's not the case and suggested he read more of his books. lol

The bottom of the BBR is the guide.

Check AS4373, also the same.

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Sean Freeman

Well as I said its where I would have made the cut in the photo, Shigo certainly has it over me and I have read all his published works even the USFD papers, I'm not disputing that his knowledge and understanding is superior to mine it was and is. Just that in the case of co-dominant stems there is no branch protection zone, all you are trying to achieve is to encourage the effective closure of the wound, and limit the production of epicormics..look if the co-dominant is advanced enough with enough live foliage and demanding equal if not greater rights to Auxin and Gibberelin control it you'll get epicormics. My concern when removing co-dominants like the one in the photo is to balance two objectives, effective closure limiting the amount of dysfunction my cut produces and reducing epicormic growth as much as poss.

Shigo's instructions re co-dominants to hit the bottom mark extended from the bottom of the BBR across to the outer bark I understand perfectly, and don't dispute. His main point was to warn of the dangers of leaving a stub live (for a time) but without a defense system. I don't consider the difference between the red line and the blue line in the photo to be that great...red line less wood tissue left agreed, but more wood tissue surface area exposed to dysfunction, the impact of which on urban trees already experiencing multiple streeses should not be ignored. The blue line attempts to split hairs by lifting the bottom slightly to reduce that area.

It's just my opinion Ekka, its not me saying Shigo's wrong and I'm right, Shigo is right I just want to try to protect the tree more, if my tree biology is wrong here I'll take pointers please.

SF

l2edneck

My concern with cuttin on the blue line instaed of the red line.would be simply to cut along the red line so the finish is below the lilttle latteral that would be left just below the blue line cut.

If left unnatended would keep the wound open and also fight for dominance.At the same time getting heavy and being on the side of the stem leaving more room for failure due to what i have dubbed the "peel effect".

This IMO could be avoided with the redline cut as long as no sprouts or suckers as we call them are left on the other side above the finish cut....
(Now that would be a cleanup cut (both red and blue) ,obviously its not healing because it was cut wrong to begin with..Easy collar cut could have been made at the initial trim.)

Personally i think that if it grows that good and comes back im questioninq why leave the other side.But i have no clue about gums in Au.

Eric Frei

I also laid the challenge down somewhere about the myth of heartwood not having defense capabilities ... so did Shigo.

It's common thought to say co-dominants have no branch protection zone, hey, there's just heartwood and that's the only defense so leaving more of it should do better????

I accept the rationale and logic of this. I also used to prune way shyer of the red line till say the last 7 years.

There's defense capabilities of heartwood, we need to find some facts on this but I can only find generalized statements and some diagrams showing whats called the barrier zone where the heartwood alters.... but no real scientific data.

Also, perhaps cutting to the red line will mean faster closure. On some species I noticed that cutting off the mark resulted in the bark dying back a bit and bit of a dead stub. Remember back in the old days they flush cut as closure was rapid. In Shigo's dissected trees you could clearly see how the living part formed a barrier and the wound was compartmentalized.

I'm a red line cutter too

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Sean Freeman

Well i seem to have merely produced more confusion rather than some clarification which was my intention, and thats definately down to me not being able to explain what I mean i quess. So I'll try to be clearer, and please note I'm not suggesting that others have said this merely that I hoope this makes my opinion on cutting co-dominants clearer...

So what I don't mean:
Pruning cuts on codominants should be perpendicular or (close to it) to the outside of the branch or limb, no.
Pruning cuts should be flush, no never.
That heartwood is dead, no its not, (but its not alive either)
That heartwood has no defensive processes or mechanisms, no heartwood does have those processes and mechanisms otherwise CODIT as a model would not be applicable.


So what I do mean: There are no collars at the union between two co-dominant stems (If it helps this is a quote from Shigo Tree Pruning Worldwide Guide pg 156) making the correct cut as described by Shigo for many of the trees I cut is very hard to pick, there are no give aways as to the bottom of the stem bark ridge.
The resulting estimate I have feared that I am getting too close to being flush, cutting into more timber than I should, so I have lifted the bottom of the cut. It is splitting hairs and reflects doubts I have about my own abilities, and if I came across as lecturing on what others should or should not make their practice that wasn't my intention.
If you as the person cutting are comfortable in the species you work on in making the cut at the "red line" all well and good. In some of the species I work on it's an easy pick too, in others it is by no means easy so I err on the side of the "blue line"

It is always preferrable to have co-dominant stems removed when they are small, when the tree is young. By the time the tree gets to the size in the original photo by Ekka the impact on the tree system of removing that codominant(if it were a healthy energy producing limb) will be to stimulate massive changes in hormonal control of epicormic buds, not just in the immediate area of the cut near the union but more often than not along the remaining limb itself. (Now that will often happen no matter where you cut, but I don't mean it doesn't matter where you make the final cut, I don't mean just lop it off cause she's going to sprout.) The epicormics that are produced are not always a bad thing for the tree, but if they are around the lip of the cut of course they will have to be removed. In some of the older trees I work on epicormics are a signal of increasing stresses sure but they are very important to the maintenance of energy levels within the tree as a whole, so I'll leave all those with no target, that I can see have half a chance of forming reasonable branch architecture in 5-10 yrs.
There is no branch protection zone behind the cut you make in the case of codominant stems there is a barrier zone that forms in the wood grown after the cut is made, but "co-dominant stems do not have protection barriers" (again if it helps that is Shigo Modern Arboriculture pg 108) So again my cutting slightly above the "red line"is about trying to ensure that I don't end up making an error that results in excessive cambial dieback under the cut opening up the limb to increased borer attack (longicorns in the case of the Albizia saman I spend so much time looking after)

Look I hope that's clearer about where I'm coming from?

SF

Eric Frei

Yeah, that's real clear.

Just kidding.


Boa, we gotta get some pics now of different cuts that were done a while ago and have a look.

I draw your attention to Exhibit A, this was a co-dominant cut more so toward the blue line than the red. Now the reason why the bark has gone to where you can see callus wood growing is because I broke it off by hand to see if closure was taking place. Note where it was cut it died. So if this cut were more on the mark of a red line it would have been hunky dory. Also as you cannot see the bottom of the BBR but just note where the callus growth has occured ... way lower than you'd expect, more toward that flusher zone.

Now because the guy who cut this stayed away from the red line the wound will be exposed longer as the callus has to grow more distance to cover the dead stub which is a bug feast.

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Sean Freeman

Ekka, couple of points; 1) the cut you show is almost perpendicular to the branch, thats not the cut I would have made.
2) The tree species I'm not sure? Would seem to be a relatively weak compartmentaliser, so perhaps I would have moved closer to the red line than the blue, but hey mate the difference between the two would be flat out being 20mm. If It is a relatively weak compartmentaliser (maybe not as bad as Delonix) then I don't think even if you hit the cut on the red line mark you'd prevent that cambium dieback, so you'd still have the insect feast countered by the vitality and energy reserves of the tree.
If I can see the stem bark ridge then yes I would make my best attempt to cut strictly according to Shigo's model, if I can't and maybe its my eyes but on many trees i work on i can't see it, then my cut will move fractionally up to the blue line. But its in no way a stub that I leave.

SF

Eric Frei

We'll have to get some pics, this is fun and very normal of what goes on.

Some trees also have infinous BBR that would simply be ridiculous to use the red line model on ... I'll have to take some pics of them.

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Sean Freeman

Ok cameras at 50 metres, lets hope I can find some shots to support my position!

SF

Underwor

In post #6, your red line is just below all the new sprouts from latent buds. Am I right in saying that on an older cut, such as this, which you might be "cleaning up", these sprouts might be an excellent indicator of where the enzymes that control the bud opening are getting to from the remaining top growth and where the circulation system is lacking those from the old cut off top? (Nasty sentence, but I hope you get the idea). If this statement is true, then this shows the limit of the area where the wood from the remaining trunk will start in its quest to cover the resulting wound. This would make Ekka's cut more preferable to the one described later at a slightly higher position, even though the wound would be larger. It should seal with out having to go over a small dead triangle which may develop below the higher cut. Did I properly confuse everyone?

mdvaden

"Go ahead and make my day !"

Eric Frei

Darn it, palms dont have target cuts so that cuts 3/4's of my work out. lol

Underwor, what do you know of, or where could you direct me to for information about the protection properties of heartwood.

Also pines, clearly have an abundance of resin in the heartwood as they ooze all over.

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Underwor

Okay, you asked for it. I just hate it when people ask a question that makes me have to think and study, but it does make me learn also.

According to Alex Shigo in his "New Tree Biology", true heartwood is part of the trees natural aging process. Discolored wood is injury altered wood. The level of resistance to invasion is different between the two. Only by understanding the difference can we understand why one area of "heartwood" rots and another does not. At this point I am going to include a link to an old photo I took when I worked at Western Illinois University. As I studied up to write this article, I realized that the pattern that was exhibited here, shows exactly what Shigo addresses in his description. http://165.234.175.12/photos/Arbor/C...zed%20Burr.jpg

First a quick differentiation between people and trees. Human aging is measured as a ratio between cell breakdown - autolysis - to restoration in the body. We can make new parts as they are injured or worn out. Trees only generate tissue, they do not regenerate tissue. Therefore, the ratio of aging is based on the volume of wood that can store energy - dynamic mass - to volume of wood that can no longer store energy. (Here I insert another link to a PPT presentation that talks about energy management in trees on both an annual and lifetime basis -- http://165.234.175.12/photos/Arbor1.ppt )

With no outside factors stressing a tree, it's biggest worry is that it could outgrow itself, it is a generating system. The tree must protect its generating system and its mechanical support system. As a tree makes energy, it needs a place to store this energy. This is in the "living" or dynamic mass of the tree. If too much dynamic mass is created, in relation to energy production, the tree may use more energy keeping this DM alive than is created and starve the tree to death, but it needs enough DM to store energy for growth spurts in spring and to fight invasions of various disorders.

Keep in mind the previous statement that there is a difference between heartwood and discolored wood, we will come back to that. There are many ways that the tree, in its effort to ensure mechanical support, alters wood to prevent breakdown. These include "denser wood, cell arrangements, chemicals within cell contents and cell walls to resist pathogens -- extractives, antimicrobial substances -- alteration of micro environment -- extremes in oxygen, moisture, pH, elements, electrical state --and another 'last ditch' method that is seldom considered: 'invite' some mild pathogen in that does not break down wood but will keep out others that rapidly break down wood -- wetwood." (Quoted from New Tree Biology)

In a tree which is not threatened by a pathogen, the balancing act between dynamic mass and energy production is controlled by the age altering of inner growth increments to take them out of the storage process. The tree does need this wood for support, if it breaks it dies, so it alters it to resist pathogens which may try to destroy it. This is a top priority and is a static situation. If an injury does allow a pathogen to enter, the injury altered discolored wood, which is formed also takes out some of the storage capability, but not according to nature's plan. This compartmentalized wood has different characteristics, including being dynamic in nature to meet the changing invasions it faces, than the age altered heartwood, even though both are protection wood and dark colored.

Now go back to my picture from WIU. The tree, a Burr Oak, started out in a savanna type area on the prairie. As it aged, the balance of generation of energy and storage were maintained by the tree with the creation of age altered heartwood. The tree, did not need that much storage, but it needed to ensure mechanical support. The area later became a golf course for about 20 years and then part of the college campus. During this time of change, stresses and injuries lead to no doubt numerous disorders. More discolored wood was formed, but this was injury altered and a part of compartmentalization. The disease was better able to invade it than the heartwood at the center, formed under a different system, and the resulting pattern ensued.

Hope this made sense and was not too long or too short, Alex has 40 pages of photos and information on the subject.

The use of bacterial wetwood by trees to prevent rotting is a whole nother story.

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Bob Underwood, Associate Professor of Forestry
ND School of Forestry
Minot State University - Bottineau Campus
Bottineau, North Dakota

Sean Freeman

Very well written Bob, my own area of fascination is with the changing relationship between tree and fungi alternating from symbiosis to pathogenic, back to symbiosis (or variations on a theme between the two) I feel that the trees I deal with often maintain unexpected relationships with "mild" pathogens for precisely the reasons Shigo alluded to, that the chemical boundaries produced by the fungi are far more effective at repelling other fungi than the chemical boundaries formed by the tree.

So I've been out taking some photos and have placed onto the shots where I think the stem bark ridge is and therefore where the final cut should ideally be made. I have added the blue line to indicate where I think I would make my final cut. I've been as honest as I can in placing the lines, and accept that others might feel I've put the end of the stem bark ridge in the wrong place, but I hope you can all see what I'm attempting to show.
A caveat, I would't actually remove any of the co-dominants shown in the photos, there is no justification with regards risk or public safety in my opinion. In one shot where the cut has been made, I'm at a loss to understand why the limb was removed at all.

This is Eucalyptus xanthoclada good compartmentaliser, strong resilant unions provided no bark inclusions, very often hollowed by root damage>fungi>termites.

This is Delonix regia very poor compartmentaliser, produces long horizontal scaffolds often self conflicting and grafting, very susceptable to fungi colonisation and termite infestation.

This is Eucalyptus torelliana when undamaged fairly reliable unions, elongated limbs are susceptable to over load failure, we often call this one snappy gum because of its tendancy to snap out during t/ds.

The last two are of the same gum and indicate a real problem for tired or hurried climbers. The first shot has me making the same cut as the red line hence the purple line!, but when you move round the other side some would perhaps make the red line cut, I'll be honest and tell you I think I would make my cut at the blue line, the tree is Eucalyptus tereticornus usually when healthy good compartmentaliser, limb unions reliable. .

SF

Eric Frei

Excellent Bob.

As I understand it in prefered environments trees have more energy to store and that improves the defense qualities of the heartwood.

Here's another curly question, rays, can they also transport into heartwood to supply resistance to pathogens?

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Underwor

Close. A healthy tree, which keeps expanding in size, has the potential to create energy at an ever increasing rate as the leaf surface increases. If it tries to store all this energy, it must create more of the living parenchyma cells to do this. (those seen when we stain wood with Potassium Iodide solution). Since these are living cells, they require energy from the tree for maintenance to keep them going. At some point the tree would be using so much energy to maintain storage space, that none would be left for defense or growth and the tree would die of starvation. To balance this, the tree reduces storage by altering some cells to create heartwood. These cells are no longer alive, saving energy needs, and they have been fortified with protection to keep them strong in supporting the mass of the plant. A tree growing in less favorable conditions would most likely just produce less heartwood, as the amount of storage space would be expanding at a slower pace and oversupply might not be a problem. OR, It might have more heartwood, since it does not have much reserve energy to support the storage facility, therefore storing the bare minimum for survival.

Remember, the defense of the heartwood or mechanical support is the tree's first priority, then comes defense against diseases, which is more difficult as the tree is facing a moving target.

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Bob Underwood, Associate Professor of Forestry
ND School of Forestry
Minot State University - Bottineau Campus
Bottineau, North Dakota

Sean Freeman

Once again very succinctly put Bob, but in terms of our discussion about pruning cuts and in particular the impact on the tree's energy resource allocation your last comment does produce some confusion for me.
Remember, the defense of the heartwood or mechanical support is the tree's first priority, then comes defense against diseases, which is more difficult as the tree is facing a moving target.
I'm perhaps reading it incorrectly (if so please correct me) my understanding of the preferential allocation, or consumption of energy within the tree system is as follows, (allowing for slight variations due to age, species, enviro conditions and past cultural practices)

1 new foliage
2 new roots,
3 reproduction,
4 sinks in the canopy
5 sinks in the stems,
6 diameter growth,
7 tree defensive chemicals come last.

Part of the skill gained through learning, and experience for an Arborist is to understand the dose that is appropriate for a partcular species in the particular environment in which it is living. Removal of any living tissue from a tree has an impact on the established growth control pathways, energy production levels, storage capacities, and (massively) energy demands within that tree. The fact that the tree commits energy resources preferentially to other (very important to immediate survival) activities before chemical defense has obvious serious implications.

Part of my concern right at the beginning of this thread was to highlight why I felt that pruning of established mature and significant co-dominant stems is an area of great concern for any arborist. We probably should enter into the discussion of the growth control pathways. (and I would like to do that with you Bob, because I know your forestry experience would teach me a hell of a lot)

SF

Eric Frei

We'll have to start paying him for tutoring soon.

Here's a union hard to tell where the BBR is, front and back shots.

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Eric Frei

Spotted this on the side of the road.

The first picture shows it as I found it, notice the bark toward the bottom, now in the rest of the shots I pulled that bark off looking for where the callus growth was.



You'll clearly see the trees response.

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Underwor

Support is the trees first priority as regards the production of anti-decay activities. Compartmentalization is second in this regard. There are as you say, many other things that are higher priority in the whole scheme of things.

Hope this clears things up a little.

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Bob Underwood, Associate Professor of Forestry
ND School of Forestry
Minot State University - Bottineau Campus
Bottineau, North Dakota

Underwor

I started to address this a little in post #19. I'll try to get more specific later.

What are your thoughts about leaving a long stub, so that the tree will start to compartmentalize near the proper place for a cut, while the entrance for pathogens is still a long distance away. The theory is that this starts the process while the pathogen is a long way from the tree's heart so to speak, then you cut off the stub. It also makes the proper place to cut the stub easier to see, since the remaining stem will have started to grow around it in a year or so, leaving a very definite ridge. Of course, this is more labor intensive, but it might be something to consider on your higher end customers, who take a deal of interest in educating themselves as well as caring for their trees.

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Bob Underwood, Associate Professor of Forestry
ND School of Forestry
Minot State University - Bottineau Campus
Bottineau, North Dakota

Sean Freeman

Yes thats very interesting and has some merit, but as for having clients who are going to follow the explaination of why i would be leaving a stub then returning later to remove same stub, can't see it, not in my current market place.

But in terms of what is actually going on in the tree yes I'd agree with the arguement that the tree will form both chemical and physical barriers behind the cut irrespective of the final location (given its away from the ideal finishing line) Not sure how you'd locate the that ridge in some of the species we deal with up here, also there is a limit to that distance.. if you leave a long stub you leave numerous meristematic points from which reassertion of hormonal growth control will be attempted.(To complicate the situation even further in some circumatnces I would argue permitting epicormic growth to occur can be beneficial in the stimulation of raised cambium vitality in larger limbs)

In the rare occaisons I've worked on veteran trees here in Oz thats been exactly my approach, since with secondary branch unions the tree system will do all its going to do behind the cut, once that damage is made. There are of course some big variations in approach...dose when it comes to branches (even secondary) with huge storage capacity ie very large diameter limbs, then my approach along with Steve has been to try to persuade the client to allow us to stage the reduction of that limb over 12 months or more leading to the final removal with the ideal finishing cut. Our logic being lets try to permit the tree to withdraw what resources it can from the limb over the time we are reducing it. (Talking about limbs >500mm dia) But thus far there's onlt been two clients that have accepted the logic of that arguement. (after all the cost is the same for them at the time of quoting, we'd make some allowance for the extra travel but honestly not enough)

Of course the other aspect with older trees..veterans is that you stop percieving them as single biological entities and see them in their real role within the ecosystem as a whole, some of thosse fungi are more ecologically fragile than the tree, providing them with a niche is pretty darn important too (but you and I can maybe discuss that in some other thread)

All of what we and others have touched on is all relative to variations in species, age, environment and past practices, not a cop out just recognition that how I approach dose for a young mango is vastly different to that for a mature eucalypt. In fact with mangofera indica, tamarindus indica, and ceasalpinea ferrea (all great compartmentalisers) I would have no reservations in leaving a short stub to be removed on a second visit perhaps 6-8 months later, but we're talking about co-dominant stems here and these species have very well defined stem and branch bark ridges so finding the ideal line for the finishing cut should not be a problem anyway.

I"m assuming all of the above probably comes accross as overly complex but honestly I don't believe it is, each tree has its own genetic imperatives, working away through the restraints and limitations of the environmental circumstances it finds itself. Any absolutist model of this is the precise location of the final cut for an equally divided branch union such as is the case in co-dominance I think will lead to errors that are avoidable.

My way of trying to limit my margin of error has been when in doubt in make my cuts in the locations indicated in previous posts.

SF

Eric Frei

It would be good to get comparable pics on the same tree, one cut to target straight off the other a year later then disect it 5 years later and see the difference. The difference neasuring the internal into the stem.

If indeed the heartwood is not resupplied and what is there does the work then there'd be little if any difference IMHO. It's not as though the heartwood is gaining anything in the next year as far as decay resistance is it?

However the cambium would perhaps be given either another season to grow or die, but that would be one season less in closure.

I'll take it as a theory at this stage till I see supportive evidence. I understand the merit but I have cut off many dead stubs where the bark has had to grow along rather than around, not much else achieved. If the stub was like 2' away then the target cut is pretty much a fresh cut as it would have been in the beginning. If the stub cut was closer like 6" away then the target cut reveals a semi decayed heartwood cut.

In my pics you'll notice some where dead stubs remained.

Subordination over time of a co-dominant stem can turn it into a collar, but that would be a long slow process.

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