What Could Go Wrong? Felling a 95 foot Douglas fir tree with two tops

Sometimes precision timber felling doesn't go exactly as planned. If we take all the usual steps and precautions, what could go wrong?

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This is the first "What Could Go Wrong?" in a social-media series about the risks and rewards of managing our own forests -- particularly the risks. It's one way for us to share what we’ve learned from years of work on our small forest in the Pacific Northwest.  When we undertook thinning our wooded acres it seemed perfectly reasonable that we could do the work. We had no idea how true Murphy's Law really was. Sometimes it's funny, sometimes it's extremely frustrating, painful or expensive. We find ways to fix the things that go wrong, even anticipate and avoid them -- particularly where our personal safety was involved, which is all the time.  And we learn from our mistakes. Smart people fall into heuristic traps where they think their situation will be safe enough, then they get injured or killed. Staying alive amid the dangers of logging takes more than knowledge or luck. If you make a mistake and survive, you still made the mistake, and the odds will get you someday. When we face a hazardous situation and we do everything we know to mitigate it, that doesn't mean we're out of danger, it just means we're out of ideas. We hope you'll pick up new ideas here. We still are. In this series we'll admit to some mistakes and share what we've experienced over the years of managing our forest, studying, taking training, and helping our neighbors. There will be videos, photos and blog stories about some of our tense moments. We're humbled by people who do this work for a living. (We're descendants of people who did.) Be safe and keep your sense of humor, Denis and Linda

Clearing big trees to create defensible space for a Firewise home doesn’t necessarily mean the end of the line for the trees.

This was a 95 foot Douglas fir on a steep slope -- typical for the Pacific Northwest, but it has a symmetrically forked top, which our neighbor wanted to save and use in his log house. The tree needed to fall across the slope onto a bulldozed lay he prepared, to keep the fork from breaking.

 

What could go wrong? The tree survived a forest fire 20 years ago and might have internal damage. Loose dirt made it hard to work on the uphill side where I’d rather have been -- The limb weight was definitely to the downhill side. On this densely vegetated slope it was hard to get to a place where I could see whether there was any forward or back lean in the tree. If there was, it wasn't much.

Boring behind an open-faced wedge cut.

 

I used an open faced cut with a plunge cut to set the hinge. Everyone has their philosophy on technique. I used this one because it makes the tree fall more slowly, to protect the fork.

 

Then I cut out the compression side. I set a felling wedge, just in case.

 

The felling cut involved quickly tripping the tree by taking out the hold wood on the tension side. My cut intersected with my bore and...the tree sat back and trapped my saw.

 

I had a wedge in the cut, so wasn’t a catastrophe.If my bar weren’t directly under the wedge, I could’ve freed my saw. Instead I had to wedge the tree over. I tried to fit a second wedge into the cut, but it was too late, the tree had closed. I couldn’t get the bar and chain out of the tree, but I could remove the power head. With that out of harm’s way I could wedge the tree over safely to the lay.

Felling cut, and bulldozed lay where the tree needed to fall.

 

The tree hit its target. The symmetrical fork was intact. My hinge was 16 by 1-1/2, almost exactly as I had planned.

 

But when the tree trapped my saw it increased my risk until the tree was on the ground. I had to spend time under a cut-up tree, when I'd rather just finish the cut and skedaddle. Plus I had to reassemble my saw before I could go on to the next tree. All of that was avoidable.

 

In retrospect I wish I’d made the felling cut from right to left, even though it was an awkward place to stand. In one of my earlier videos I showed Chris doing this right. His bar was pinned when a tree sat back, but a few taps on the wedge released it.

 

Undercutting the felling wedge has another pitfall: It decreases the lift of the felling wedge. In this case my bar and chain were trapped in the kerf under the wedge, filling it, so no lift was lost and a single wedge worked to fell the tree. Had I been able to remove my bar from the tree first, I'd have to insert a second wedge in the cut below the first one (stacking wedges is a topic for another video). Otherwise the gap would collapse under the first wedge -- I'd subtract the 3/8 inch thickness of the kerf from the 1 inch head of the wedge. That 0.375 inches doesn't seem like much, but it makes a big difference 95 feet up, reducing the maximum throw by a third.

 

Species: Douglas fir.

 

Height: 95 feet.

 

DBH: 21 inches.

 

Saw: Stihl MS441 Magnum

 

These "tree fail" videos on YouTube offer more lessons and laughs.