Tell me what I don't know about limbing a dead tree.

[TallTreeClimber]

This giant oak was struck by lightning several months ago. It's over the bull pen, so I wanted to get it limbed and felled asap. I thought that it was strong enough to be climbing in but the tree was pretty brittle. Look what happened when I undercut these two limbs. This was unexpected and scary. I made an undercut, and the started my top cut, and the limbs just ripped apart.



Has the tree been dead too long? I remember it being alive, it seems like it was just 8 months ago.

Feed back desired.

Thanks.

 

[lxskllr]

I don't know nothin' bout nothin', but maybe treat it like a hard leaning tree, and cut like you would to prevent a barberchair. There's a thread right below that might give you ideas. Those are pretty beefy limbs. I guess they're dead enough to not be able to take the strain of cutting.

 

[Jonny]

Is it possible those limbs were already cracked/split where it broke?

 

[TallTreeClimber]

Is it possible those limbs were already cracked/split where it broke?

No.

 

[TallTreeClimber]

The tree is down. It went down the same day. Maybe I did it a little bit the hard way limbing it so much, but I felt like what I did was the safest way. I just don't know about the tree condition after seeing how some of the cuts went.

 

[Tree09]

You started the top cut right?

 

[TallTreeClimber]

You started the top cut right?

Yeah.

 

[Tree09]

Alright, that makes sense now. Dead wood, no matter the species, is more brittle than green wood obviously. Those looked like long, large horizontal leaders, which are exerting a very large tension force on the top of the limb. You did a simple drop undercut, but not nearly enough to stop it from tearing apart, basically like a barber chair, and it didn't tear as much because it was dead and dry.

The solution is to either climb out farther and take smaller pieces, or to approach the cutting like an extreme head leaner. You can do a coos bay cut, where you cut in on one side only, then cut the other side until it pops. You can also do a shallow face notch, then bore in to form a small hinge, then cut up if needed, then cut the holding wood. You can also ream the drop cut as it starts to close, but since that requires reaming with the top of the bar, I've never done that.

Also, from what i can tell from the pictures, you did your top cut father out than your undercut. Doing that increases the likelihood of your saw getting snatched, and that's no good. Also, be very very careful with putting your lanyard around a huge horizontal leader you are cutting, if it tears it could crush you by splitting farther back and jamming you into the tree.

 

[Mellow]

Those brown patches on the bark look like hypoxylin canker. That will make the wood very brittle, very fast.

 

[greengreer]

Big heavy leads like that I try to remove as much wood without releasing the piece as possible. Get your undercut deep as possible without a pinch, then cut the sides out about as much as you can get away with. Release with full throttle, sharp saw as close as you can get to lining up but err on the stub side so the saw won't get snatched. Alot of times I'll have a faster cutting saw sent up, even if I have enough bar length on the top handle just to be able to cut the fiber quick enough to eliminate the split.
I agree about dead wood being more brittle than live but there would also be less weight out there to initiate a split in the first place. Does look a bit like hypoxolon too, but hard to tell from the pics

 

[TallTreeClimber]

Those brown patches on the bark look like hypoxylin canker. That will make the wood very brittle, very fast.

There was a lot of powdery brown dust patches on that tree.

 

[TallTreeClimber]

The two undercuts in the first pic are almost halfway up through the branch. I thought I done fine. Are you guys saying that isn't enough?

And one of those top cuts is within 2" of the bottom cut. I appreciate the advice on this, because things didn't go like I was expecting.

Thankfully I never came close to wrapping a lanyard around a branch that I was cutting on. This was a big scary tree for an inexperienced person like me so I was very careful.

 

[Tree09]

No that's not even close to far enough on those limbs, because they split out on you. Your choice of cut (what you did is called a drop cut) was also wrong, as was your choice of the location of the cut. You needed to be further out to minimize the leverage, or use a coos bay or bore cut. Large horizontal leaders develop incredible tension on the top side, and sometimes hardly any cutting on them will cause them to just go. Think of the weight that the limb has, how far out the limb goes, then think about the stresses in the wood of the limb. Then think what happens to the tension wood when it's cut, what's left to hold up the limb? It takes less force to split the wood, so it simply splits.

The weird thing about doing trees is that as a beginner, the climbing is daunting enough where you think that cutting close to the trunk is safer, when in reality cutting smaller pieces farther out is. When you cut close to the trunk, you are forced to deal with large limbs with lots of tension, which can split out on you. They can also hit tip first and shove the butt towards the climber, perhaps hitting him or even pinning him to the tree.

Your top cut needs to be closer to the trunk than your undercut, that is very very important. You will either lose your saw or get hurt if that is messed up. Precision in cutting is just as important in the tree as it is on the ground, but you can get away with more if the piece is very small. But having said that, even a small limb can grab your saw if it's cut wrong.

 

[Mellow]

There was a lot of powdery brown dust patches on that tree.

A sure sign of hypoxylin canker. Hypoxylin is an opportunist that will not affect healthy trees. The lightning strike was probably the trigger that led to its demise.

 

[SeanKroll]

You can do a coos bay cut, where you cut in on one side only, then cut the other side until it pops.

Not my understanding of a Coos Bay cut.

Cut one side, then the other, leaving a strip. Then, cut top down a fast as possible. To strip will tear at the bottom.

On limbs, I'll undercut a little, closer to the limb base, like sapwood cuts on a topping face-cut/ backcut.

 

[DMc]

Lightning would do it, but so would penning heavy stock in the critical root zone. Major sorce of soil compaction and excessive salts. That large stump next to it could also have vectored pathogens.

Glad you did not get injured. Guys here have given some good advice.

 

[Tree09]

@SeanKroll i think you are right, but i would think on a heavy limb you would never get to the back cut, because the force is so great and there's really not that much wood there. I've used it the way i described a few times, but i am not very experienced with it, mainly because i usually force my fat ass out farther on the limb Jerry uses it here too i think, at 1:45 or so. I can't tell if it's a drop cut or coos bay, but the way the limb snaps it looks like a coos bay i think?

 

[SeanKroll]

Looks to me like a bit of an off-angle (strip of holding wood is not dead vertical 12:00 to 6:00) Coos Bay, at 1:45.

I think it's all about proportion. If it won't hold, you've cut the strip too narrow. The cutter must judge species and condition, size, leverage, etc.

In FOGT, IIRC, there is reference to cutting the side with any side-lean first, and setting a wedge.

With unbalanced limbs, due to asymetrical lateral growth, there will be some torsion on the limb. this should be accounted for.

 

[SeanKroll]

View attachment 98192

This giant oak was struck by lightning several months ago. It's over the bull pen, so I wanted to get it limbed and felled asap. I thought that it was strong enough to be climbing in but the tree was pretty brittle. Look what happened when I undercut these two limbs. This was unexpected and scary. I made an undercut, and the started my top cut, and the limbs just ripped apart.

View attachment 98193

Has the tree been dead too long? I remember it being alive, it seems like it was just 8 months ago.

Feed back desired.

Thanks.

Too dead is not what you need to know. Trees aren't too dead to climb. They are to damaged, weather from wood destroying organisms, electricity, etc.

Sometimes, dead root-diseased trees don't fail in the storms where live root-diseased trees do fail. Live trees have more wind profile, mass, and momentum.

I think you're in over your head to be climbing/ limbing large, lightning struck trees. Very unpredictable.


Why not fell it with the lean rather than limbing it?

 

[murphy4trees]

Alright, that makes sense now. Dead wood, no matter the species, is more brittle than green wood obviously. Those looked like long, large horizontal leaders, which are exerting a very large tension force on the top of the limb. You did a simple drop undercut, but not nearly enough to stop it from tearing apart, basically like a barber chair, and it didn't tear as much because it was dead and dry.

The solution is to either climb out farther and take smaller pieces, or to approach the cutting like an extreme head leaner. You can do a coos bay cut, where you cut in on one side only, then cut the other side until it pops. You can also do a shallow face notch, then bore in to form a small hinge, then cut up if needed, then cut the holding wood. You can also ream the drop cut as it starts to close, but since that requires reaming with the top of the bar, I've never done that.

Also, from what i can tell from the pictures, you did your top cut father out than your undercut. Doing that increases the likelihood of your saw getting snatched, and that's no good. Also, be very very careful with putting your lanyard around a huge horizontal leader you are cutting, if it tears it could crush you by splitting farther back and jamming you into the tree.

Now there is someone that knows what he's talking about. Why do people that don't have a clue feel the need to throw out ideas that are speculation at best? You are better of asking questions than answering them.

If you don't want the piece to split, you can make a narrow notch or mutli-kerf-cut undercut. Then make sure your top cut is right above it. It is obvious to any knowledgable observer that the pieces split because the top cut was too far out beyond the bottom cut. And as pointed out anytime you go farther out than the undercut, you risk saw snatch, and there is zero benefits to making the top-cut out further than the undercut.

On smaller limbs, you can get away with just a kerf undercut, but on bigger diameter limbs, as per your photo, you'll need to use a notch of some kind. The same is true of handsaw cuts. The kerf only allows the piece to move just a hair, as you keep cutting, the piece stalls and is prone to splitting. SO the size of the limb, and the fact that it was brittle are factors here.

The problem with branches that split like that is that if they are more vertical than horizontal when they split, they can behave like a barber chair and kill the climber. When they are horizontal, there is no risk to allowing them to split. I have become accustomed to doing that and will actually use the split to slow down the movement of limbs to ease them into the rigging. It's a little disconcerting at first, per the OP's question, but you get used to it and it becomes a no-brainer after you understand exactly what the piece is capable of doing.

 

[Mick!]

Yeah, cuts not close enough to each other, regardless of species, condition or speed of cut.

 

[murphy4trees]

To answer another OP question. NO, the tree hasn't been dead too long as oak is usually quite secure to climb for 2 years + after death, even when struck by lightning. You may, however, be wise not to rig anything much off of a lightning-struck tree, as the internal structure of the stem or limbs could be invisibly compromised. It looks like you didn't lower anything on this tree, so climbing alone was no problem.

You had concerns about the limbs fracturing in line with the stem, which had more to do with the cuts you made than any other factor. The best thing you can take from this thread is that cutting the top cut beyond the undercut can cause saw snatch. ITS A BAD PRACTICE.

Along with bad practice, comes bad advice. Please ignore Sean's nonsense about torsion on the limbs created by asymmetrical weight distribution, and using wedges on side leaning limbs. His credibility is lacking and these types of statements that have no value at all in this conversation are just another example of why.

Perhaps a conversation about limb fracturing, in general, would have some value. I made this cut on Monday and was pretty sure it was going to split the limb, though I wasn't concerned about safety because the limb was almost horizontal and there was no way for it to lift up high enough to reach my position.

 

[TallTreeClimber]

Guys, thanks for the comments, but I'm a little confused by some of them.

In this video, the three cut method can be seen for pruning near horizontal limbs.



I've seen this taught all over for many decades. It is very standard from what I understand. All I was doing was skipping the third cut, close to the collar, because I was ultimately taking the tree down. Now some of you are saying the exact opposite of what I've understood as standard practice, to make an undercut, and then an inch or two further out make a top cut. This is to keep the limb from splitting down to the collar or further down the trunk. In this thread I'm reading to make a wedge undercut, or an undercut, and then make the top cut closer to the trunk. So when does one cut one way or the other? Is there a size consideration on which method to use?

Please help me understand what I'm not getting.

 

[greengreer]

The pruning cut is just that. It's to keep you from ripping into the branch collar. Removal is a different story entirely.
The basic principle of a drop cut is to be able to cut the holding wood before the weight of the piece separates it. The point of an undercut or side cuts is to be able to keep up with the cut before gravity takes hold.

 

[Tree09]

@TallTreeClimber , if you notice, he's taking small limbs with a handsaw. It's like comparing apples to sting rays, completely different things going on that aren't related. On pruning, i still do the top cut closer to the trunk slightly so my saw isn't caught in the torn fibers, which would suck because i use a lanyard for my saw and i don't want it or me broken. I do however add a small undercut closer yet to stop any tearing.