Trees down! Trees down!
The neighbouring woodland had a few trees that had fallen over the path. So as guided learning I took some classmates from treeschool and showed them the basics of processing individual windfall.
In the woodland, there’s a path that runs through the whole two hundred acre site. It’s not on a map and it used to be part of the rail track that shipped the coal from the mines that used to be present in the area. A lot of the treestock in the woodland is birch and they love to fall over when you least expect it. Most of the time they fall away from the central track into the woodland, but on occasion they fall over the track. Sometimes they get hung up on the trees on the other side and make for a pretty but dangerous decoration over the track (for example, the sketchy birches over a path) and sometimes it and completely renders the track in accessible to vehicles and in some cases, people. On Wednesday afternoon, coming back from a day working at treecompany this email dropped into my inbox from our woodland neighbours.
I responded and told the neighbours that I’d swing past the woodland the next day after college and see if I could sort it out. The only problem was that I had forgot that I was planning to be out at a social event with the company I worked at for nine years prior to starting this Life of Treedom thing. Uh, oh – I’d just double booked myself which was a problem becasue socialising and treework don’t play nice together. In one context you wear nice clean clothes, you smell nice and generally speaking, you meet a minimum standard of sociably acceptable cleanliness and use designated toilets. In the other context, you have the permanent dirty fingernails, you smell of petrol, smell of sawdust, have sawdust in your hair and clothes, you smell of sweat and a toilet is anywhere there isn’t a person in a clear line of sight.
As there was going to be no way I could go after college and meet my social obligations I needed to hatch a plan. Thursdays at treeschool are practical days and practical days in October are nearly all climbing. Having been one of the first four people in the class to get the climbing and aerial rescue ticket, I knew that I didn’t need the climbing practice (or gear) as much as some of my classmates. So I had a word with the lecturers and asked if myself and two of my classmates (Jamie & Dan), who’d also also passed their climbing ticket, could go to the woodland and do a real job - clearing the path of trees. As both of the classmates were over 18 years of age, safe-guarding rules didn’t apply and we were given the all clear to go and do “guided learning”.
To be honest, I was expecting the green light so I packed the car before I left for college with the following gear:
2.4 tonne hand winch, 12mm steel rope and the handle with various strops and blocks for dragging and redirecting.
2 chainsaws - you can never have too many.
fuel & oil - because machines don’r run without fuel.
water and caffeine - because humans don’t run without fuel.
In the worst case scenario of being denied a little field trip, at least my tools would have a nice day out.
When we got into the woodland and down the path we found this.
I was expecting a single birch over a path. I was not expecting three trees, with entangled tops. Technically this made the situation “multiple” windthrow rather than “individual” but I was not about to walk away from the job. We came to clear the trees and get the path open, so that’s exactly what we did.
First thing was first, we got the “caution - tree work” signs up and in place. I’m learning that the general public, even in the presence of multiple fallen trees over a path with people using chainsaws on said trees, will still not stop to think and will go about their business as if they are magically immune to being crushed to death. Even though we were working on path with no public access in a private woodland, the signs would hopefully discourage people from crawling underneath the trees as we worked on them. I was wrong. One member of the public actually crawled under the trees. Now to be fair to that person they did ask if they could. I suggested they didn’t. However, they did.
Next we got to work. The biggest part of dealing with windthrown trees is the winch setup. Jamie got to work on that whilst I examined the trees to get an idea where the tension and compression might be. I say “might” because it’s all a giant guess with some clues available.
Tension and compression is one of those concepts that takes five minutes to learn and much, much longer to master. It’s tricky because when you learn it, it is often taught with a simple single situation such as below.
Here we have a nice straight log balanced on top of two smaller logs. If you were to cut through the log in the middle from the top you would find that your saw or bar would get nipped as the weight of the log pushed against your saw. This is compression, it is highlighted in yellow. If you cut upwards from the bottom you’d find everything would go fine as the weight of the log would be pushing the fibres away from your bar. This is tension and it is highlighted in blue.
But it is not that simple. Few things are because if we take the that same log and change how it is supported, we effectively reverse the tension and compression. In this scenario if you didn’t want your handsaw (saw a log by hand and you are a psycho) or bar to get pinched you’d be able to cut from the top down - mostly. I say mostly because you always need to cut some of the compression on a simple cut. If you don’t then you could still get your tool pinched as you finish the cut. Not always, but sometimes.
The two above examples are how you’re often taught about tension and compression, but once you get out there and start learning as you work, you get a feel for the nuance of it all because you end up getting your bar pinched by compression wood a lot.
Consider this tree, that for whatever reason is growing at 45º. This tree is able to survive by having grown wood that is designed to live under tension and wood that is designed to live under compression. If you turned this tree into a log, those very same forces would be present in the log and the timber it produces. Woodworkers called “internal stress”. If you’ve ever run a circular saw through this stuff, or run this stuff through a table saw then you’ll know what happens. It either bends like a banana or pinches the blade like a clamp. If you’re using a circular saw you’d experience this as kickback (if you’re not expecting it, then it can really spook, or even maim you) and on a table saw with lots of power you’d get smoke and a very burned cut, or on a table saw without lots of power the blade stops spinning and you start killing your motor (this is my reality).
Whilst the below photo shows a stem, the same logic applies to larger limbs. This is a a second dimension of tension and compression.
With windthrow you have one more kind of tension and compression to take into account. When a tree falls, especially when multiple trees fall, they tend to get intermingled and locked up with each other. Their branches and stems get pushed and pulled and this introduces a third dimension of tension and compression. This kind is by far the most dangerous. This kind of tension can actually explode and if you’re standing in the path of that explosion and it contacts you then at best you’re walking away with a bruise and at worst you’re getting torn up and stabbed by wood fibers.
Finally, you also have to keep an eye out for branches that have been pinned down by heavy limbs or stems. Because as soon as the weight of those limbs or stems is lifted, they’re going to spring back to where there want to be. Again, you don’t want to be standing anywhere next to it when they do that.
So when assessing what was going on in this situation I was considering all of the above mentioned forms of tension and compression. I was especially mindful of the hazel that was underneath these birches as I’ve taken a couple of blows from it before I was determined not to let that happen again today.
When winching windfall, ideally you want to be winching from the rear of the tree to ensure that you’re not introducing any additional lateral forces into what could be an already sketchy scenario. However, that’s not always possible and it was not possible in this situation.
The tree we were winching was a 14 inch diameter birch, so we needed to set the winch on a birch the same size (same species same strength) or on a smaller diameter but stronger species such as an oak. However, there was nothing suitable directly behind the tree, so we had to settle for a less than desirable angle.
We’d not really covered what to do if you couldn’t get the winch setup directly behind the tree when I did my qualification but as we tensioned up the winch I could see that our winch angle, whilst not ideal, was working in our favour. We were adding tension into the tension side which meant that once the tree was severed it would act in a (reasonably) predictable way.
In the above photo you’re looking at the tension side. If the tree was going to get explosive it was going to do so on this side. When doing windfall, you do a two part cut (called a j-cut) where you cut the tension side first and the compression side second. This puts you in a safe place if the tree suddenly explodes with tension forces. Because we were adding tension to the tension side, this made matters quite predictable and the main tree came down without any fuss. I didn’t get any photos of that because I was too busy doing the cutting.
The gods must have been smiling on us on this day because not only was the weather glorious but as far as learning situations go, this one was perfect. The tree on the top had a twin leader which meant that Dan and Jamie could use one leader each as a training ground for learning how to do windfall. I didn’t get any photos of Dan doing it as I was on the winch, but here you can see Dan processing his section once the winch was taken off.
Dan was winching for Jamie and this was his first ever windfallen tree so I stayed close at hand to answer questions and provide any existential prompting such as “I’d stand back a bit if I were you”. I didn’t have to do any though, Jamie dealt with it just fine.
Once everything was and severed, it was just a case of winching everything backwards and attempting to pull it out from the crowns of the other trees.
However, whilst we managed to pull it a fair way, we couldn’t get it unpicked all the way. It became stuck and lodged. We had introduced a tonne of new tension and compression and so we ditched the winch and got up onto the path to manually unpick it all, section by section.
Because we’d introduced a lot of new tension and compression we had to play it safe and test each limb before we cut it. Testing a limb is easy - push it with your hand or foot and if it moves freely you’re good. If it doesn’t, see where it goes and repeat the test. Keep testing and cutting until you’ve got no more tree left.
We made good progress and Dan and Jamie got a load of practice with dealing with this kind of thing. However, my stomach alarm went off and we stopped for lunch at about 1 o’clock.
Time was cracking on a bit and I had to get home for that social event so after lunch I walked up the final limbs and severed them all so we could get on with the clean up and get out of there. I needed to be back in the house by 4pm, so that I could get cleaned up and drive into Newcastle for 6:30pm. It was currently about 1:45 pm so I needed to be out of the woodland by 3pm at the latest.
A few non-standard cuts and in a few minutes the path was technically open again.
As this is a woodland and not a domestic tree job, clearing up is MUCH easier. On a domestic job every leaf, chip, snapped twig has to be removed. It should be undetectable that any tree work has taken place. However, this is a woodland so the clean up is basically moving the limbs to the side of the track and stacking everything to make it harder for motorbikes to get off the track and into the woodland.1
Stacking the debris like this also creates fallen deadwood habitat - vital for woodland health. Bacteria and fungi colonise the wood and degrade the cellulose, insects digest what is left, birds, mice, voles and other small animals eat the insects, birds of prey and owls eat the small mammals. It is a real circle of life situation. There’s more to it than this, but you get the idea.
Deadwood good.
And that was that. A cracking day out in the woods, Dan and Jamie got some windthrow practice in and a nice community deed was done. I also made it to that social engagement, and it was lovely to see everyone and catchup. Wordup SoPost!
On a side note: things are hectic right now. Hence I’ve not been publishing much. Between college, working at tree company, life and other obligations, finding time to write is hard. Even this post is a month old!
I appreciate your attention.
Thanks for reading,
Cheers,
Jamie
Motorbikes are an issue. The riders are all take take take. No give. That’s not cricket.