Thinning

Redtree

Active Member
Colb, I think you make a good point about thinning being a side effect. perhaps I can create context. Imagine a Freemanni Maple, with one to one stem ratios the whole way. Reducing by some definitions may completely ruin the tree. Doing nothing leaves the tree to choke itself in the long run. A combination of thinning and reduction, or more simply put, 'structural pruning', may be the best mitigative approach. Lightly reducing with 3/4 to 1 inch cuts leaving a 1/2 or 1/4 inch stem, then thinning below that reduction cut. This slowly improves the structure while retaining enough size and fullness. I say 'slowly', because structural improvement in trees with serious issues and/or genetic tendencies is best approached with high frequency pruning cycles. These trees need a high dosage, not with a heavy application weight, but with a frequent, medium application weight.
 

Redtree

Active Member
good point JD3000, specifications or guidelines on a work order could specify a ratio of reduction cuts and removal cuts, or use them otherwise in more specific ways. Like my previous post you could replace 'thinning' with 'removal cuts'
 

colb

Well-Known Member
A reduction cut differs from a thinning cut in that the cut diameter is larger than the remaining stem diameter. Thinning involves removal cuts, which are smaller than the remaining stem. One ISA definition, I think from the small pruning handbook, states that thinning is done "at the outside edge of the crown". I think a structural pruning application should include thinning (at the periphery as all proper thinning should be) and reduction cuts. I don't think there is a time to thin and a time to reduce as much as there is the need to hybridize the two. Some trees may need 70% reduction cuts and 30% thinning cuts, while others need the opposite. Soft Maples vs Sugar Maples. Norways may need reduction cuts up to 2". Sugar Maple may only go up to 1" and Silver may be up to 3"
But yes, I do think thinning is a very misleading term. It leads to "thinning out", which is not a term. Thinning could still be used as a term but perhaps it is a good idea to phase it out. Most of the Reduction I do involves some thinning cuts, but I probably have never specified or attempted to apply thinning as a complete application. Otherwise, I do think thinning would be very effective on a high frequency cycle, pruning maybe every 2 or 3 years, starting from the beginning of establishment, through the entire period of rapid growth. But this would be mostly impractical, considering we show up after the tree is grown and vulnerable.
But why is a technician actually thinning when they do? They are not trying to retain branch extension, or increase taper. To me, the need to retain branch extension is a synonym for lazy pruning elsewhere in a canopy. Taper is increased by both reduction and thinning, but moreso by reduction.

Again, I think thinning while engaged in current structural pruning standards is purely coincidental. It's not bad in that context, or good. It lacks intrinsic value along the gradient of the good/bad contrast set.

For example, the smaller limb at a branch union extends to contact a limb in another section of canopy, frictioning against it in the wind. You prune it off. It's a structural correction that only happens to be a thinning cut.

Another example: 10" diameter Bradford pear with a dozen leaders emanating from the main trunk, all with acute junctions and included bark. You cut it down and start over right? Lol, but for real this is not a good time to be pruning. If you *did* prune it, you might cut out the middle ones to broaden the branch union angle. Some of those would be thinning cuts, coincidentally. Again, I'm not suggesting actually doing this to a Bradford pear (bracing, replanting, leaving it alone are usually going to be better options in my view...), but just using it as an example.

What is an instance where thinning is done for it's own sake for the betterment of the structure of a tree? I can't think of one.
 

Leroy

Well-Known Member
At its simplest, the difference between thinning and reduction/retrenchment is whether you prune the big branch or the small branch at the union. If the goal is lever shortening and the development of taper, then you reduce. If the goal is structural, then you try to reduce but thin if you cannot reduce. In other words, if you are thinning to improve structure then thinning is a sidelight, a coincidence - you are not trying to thin, but instead are correcting a structural issue, and might coincidentally be thinning.
So pretty much like this-

reduction cut= removal of terminal bud, pruned back to adequate lateral limb/branch
thinning cut= total removal of lateral limb
 

colb

Well-Known Member
How about using removal cut vs reduction cut instead. Loses thinning altogether.
I like the idea of subordinating the term thinning - in the context of structural pruning - to other terms. I think it is a real and tangible term though, especially in ornamental pruning where aesthetic matters more and structure matters less.

As for the term "removal cut", I would like to point out that a reduction cut *removes* a limb. It does not stick one back on, or leave the limb as is.
 

JD3000

Most well-known member
Right but a Removal Cut is defined by cutting to the collar. Of course, many a tight codom doesn't have one per say so the angle is different but I would still consider it a Removal rather than a reduction.

One way I explained it to students is like this: a Removal takes a baby back to the momma. A reduction takes momma back to a baby.

This is why talking about pruning and actually demonstrating it are so different.
 

Leroy

Well-Known Member
especially in ornamental pruning where aesthetic matters more and structure matters less.
Agreed, like I mentioned earlier certain hawthornes and crab apples is the really only time I write thin on a proposal. Some hawthornes we have grow like dense thorny bricks and can look pretty cool when they are thinned out a bit, though it is not the most enjoyable endeavor, the results can be worth it.
 

JD3000

Most well-known member
I've had to use pliers to remove thorns of Washington hawthorn from my body before.

Unpleasant.
 

colb

Well-Known Member
Right but a Removal Cut is defined by cutting to the collar. Of course, many a tight codom doesn't have one per say so the angle is different but I would still consider it a Removal rather than a reduction.

One way I explained it to students is like this: a Removal takes a baby back to the momma. A reduction takes momma back to a baby.

This is why talking about pruning and actually demonstrating it are so different.
To me, this definition makes a removal cut the antonym of an internodal cut. It does not refer to the smaller branch emanating from a branch union.
 

colb

Well-Known Member
Agreed, like I mentioned earlier certain hawthornes and crab apples is the really only time I write thin on a proposal. Some hawthornes we have grow like dense thorny bricks and can look pretty cool when they are thinned out a bit, though it is not the most enjoyable endeavor, the results can be worth it.
X2 for our native plums and hawthornes here in Florida, though I have never tried to prune a hawthorne and don't expect to ever be paid to prune one. I'm jealous you get to.
 

colb

Well-Known Member
What I think you are describing as "thinning" I would more think of as "cleaning". The ol dead damaged diseased dying crossing interfering.

Which, as an aside, I also believe can be detrimental. heard way to many tree workers say things like "gotta get those crossers out" why? lol.
I usually try to address the crossers if they are actively rubbing against each other. I consider the diameter of the cut and the ability of the species to deal with the wound. I also consider alternatives like bolting them together to facilitate grafting, or just leaving them alone.

What are the crossers you refer to, @Levi.CO ? Are they in physical contact, or impending physical contact, or just branches growing from on leader into the space occupied by the branches of another leader?
 

JD3000

Most well-known member
To me, this definition makes a removal cut the antonym of an internodal cut. It does not refer to the smaller branch emanating from a branch union.
That's what th I mean, cutting a smaller branch back to the union at the collar/natural target, blah blah.
 

ATH

Well-Known Member
..... Otherwise, I do think thinning would be very effective on a high frequency cycle, pruning maybe every 2 or 3 years, starting from the beginning of establishment, through the entire period of rapid growth. But this would be mostly impractical, considering we show up after the tree is grown and vulnerable.
I absolutely recommend pruning for structure (also call it young tree training) every 3-5 years. This is very quick and low cost and saves the client a LOT of money in the long-term. Agree, too often we are called in later to try to fix what was missed, but that doesn't mean we shouldn't keep encouraging work on younger trees.

I know you all know this, but when you are pruning younger trees, count the rings - then show the client. I've cut plenty of 2-3" diameter stems that are 3-5 years old. I show them "this is why we are pruning today...in another 4-5 years, this would have been a very significant limb, would have left a much larger wound on the trunk, and would have left a larger hole in the canopy/made it look more asymmetrical".
 

Chaplain242

Well-Known Member
In regards to thinning there are motives for it regarding: species prone to fungus, light transfer to other plants/trees, wind loading of branches, pruning for structure or aesthetics, balancing canopy to prevent structural failure, pest control.... many reasons but only becomes a concern when pruners use the term to wantonly prune the tree.

Should always have a reason to prune or leave the thing alone. Thinning has a place, but is just one operation of many in our arsenal.

Takes some courage when times are tight but upholding integrity being an arborist to professionally prune what is desired by the client tempered by the knowledge and experience we have to obtain the best outcome of the tree.
 

Stihlmadd

Well-Known Member
Some more of this going on over at yamaguchi garden service...
Yah Colb - it truely seems to be an unique Urban Arborist environment over there with such a level of time and effort spent on trees and the surrounding gardens.
I get quite the kick out of viewing it all.
 

TreeVB

Well-Known Member
I know this thread is almost a year old and hope the OP has learned from it. Since @colb recently posted, I'll say mine. I feel the whole "thinning" term is a sales pitch. Ed Gilman has some great study's regarding structural pruning which in turn give the same appearance as thinning but with a more healthy approach for the trees future. I made this video a few years ago with this topic in mind. It is a somewhat boring video, I am quite monotone, yes my handsaw blade needed replacement, and it is just raw footage so dont be at me up over it. Hope this helps "draw your picture"!
 

swingdude

De' Island Buzzer
Thinning is an awful term to be using. The only thing trees need from us assholes is deadwood removal and some very selective reduction cuts from time to time....That is in the tree. branches that touch and rub should also be attended to. many things can be done for their health on the ground. airspading and mulching to reduce compaction issues etc......basically we need trees more than they need us remember this golden rule before you start cutting away relentlessly.....less is more here.....
 
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