Winter Tree Climbing

[Jamin_Mayer]

I seem to change my mindset (to more cautious) when climbing in cold weather. Cold to me is below 32*. The obvious factor that contributes to this is the possibility of ice on the tree. Or, snow caked into the tread of my boots and then I can slip from that.

But, a less obvious thing to consider: I assume (with no real research on the matter) that tree branches can be more brittle when they are frozen. So, I use extra caution with what I tie into and how much lateral force (from limb walking) is put into the T.I.P.

Iron can be very strong as a metal, but it is also brittle. I don't know if it is fair to transfer that logic to frozen tree limbs, but I kind of instinctively do.

Am I the only one here? Anyone read anything on the subject before?

 

[Marc_H]

I think you are right. Branches seem to have less flex when they are frozen. Seems like they snap so much easier in the winter.

 

[rangerdanger]

I was thinking of something we learned about in Science before winter break called frost wedging, where water works its way into rock cracks and then freezes, melts, freezes, etc. And when water freezes it expands. So I was wondering, can the same thing happen to a rotted tree, from where it may be warm enough for rain one day, then it get colder the next to freeze it. (Like here in Kentucky, went from 65 to 30 somehting over night, with rain tonight/tommorrow then colder temps on the weekend.)

 

[Marc_H]

Yes, trees can get frost cracks. It is very common here on the SW sides of trees. Usually the truck was damaged by a mower or something first.

If cavities fill with enough water the freezing and thawing can cause extensive damage. I haven't seen a tree fail from it in a single season but over a couple years I have seen trunks split into two.

 

[TLHamel]

[ QUOTE ]
But, a less obvious thing to consider: I assume (with no real research on the matter) that tree branches can be more brittle when they are frozen. So, I use extra caution with what I tie into and how much lateral force (from limb walking) is put into the T.I.P.


[/ QUOTE ]

I do not change my TIPs during colder temps. I live in Minnesota where 32 (today's temp. by the way) is considered balmy. Trees don't really freeze (well, they can but severe damage occurs if it does happen). Check out Kim Coder's article in Feb. '06 TCIA... Cold hardening is a process put in place to ultimately resist/avoid freezing. I have not noticed a perceptible change in branch or hinge behavior in sub-freezing or sub-zero temperatures. Just ask those oaks I was in a few weeks ago, 10 degrees F at noon!

 

[familytree]

good stuff TL and good read, thanks for the info

 

[treebear]

My personal experience is that wood becomes more brittle in cold temperatures (below 0C). I find that already brittle wooded species like pine, ash, maple and beech are more brittle in the winter, a fact to be observed on how they crack into smaller pieces when felled in the wintertime than in the summertime. Another experience is that the wood seems to be weaker at the time of sapflow in the spring. Some research probably must be available somwhere on this subject, if not, someone should do it soon.
Cheers
Svein

 

[treebing]

It could be that the trees might be more brittle in the cold but this would be made irrelevant by the loss of leaves, thus a huge amount of weight taken off the branches. Unless there is ice and snow on the branches I would not think there is a need for more caution about TIP.

I would agree that 32 doesnt quite count as cold yet, that is about perfect weather to climb in because it allows you to be comfortable with a nice layer of protective layer of clothing on. no real cold so far this winter here in detroit, just a little wetness.

 

[countryboypa31]

[ QUOTE ]
I do not change my TIPs during colder temps. Trees don't really freeze (well, they can but severe damage occurs if it does happen). Check out Kim Coder's article in Feb. '06 TCIA... Cold hardening is a process put in place to ultimately resist/avoid freezing. I have not noticed a perceptible change in branch or hinge behavior in sub-freezing or sub-zero temperatures.

[/ QUOTE ]

Common sense seems to say that the branches become more brittle, but i have heard before that this is not the case. I wish i could remember exactly what was said but i'm sure it was to basically the same degree of what TL said (above). As for myself i also have never seen any diffence in branch break or hinge in cold weather. I've been helping with storm damage in PA (ice and wind damage) the last couple days and have not seen any difference in how the tree reacts to my hinge or my weight when limb walking. Just my 2 cents take it for what its worth

 

[JJackson]

One thing that I do know is that spruce and fir limbs can be snapped off easier in the winter (winter camping experience). They tend to felx more in the warmer times of the year.

 

[Marc_H]

I wonder if the moisture content has something to do with it. What do you think, dry wood more brittle than green?

It seems to me that only branches less than 4" are an issue.

We know that most trees or even branches don't actually freeze because the cells would rupture and the tree/ branch would die. It's a very interesting process as to how trees actually protect themselves from freezing.

 

[Jamin_Mayer]

[ QUOTE ]
I wonder if the moisture content has something to do with it. What do you think, dry wood more brittle than green?


[/ QUOTE ]

I like that thought. Hmm...

 

[treejockey2000]

most ththings contract with colder temps and expand in warmer temps. this would apply to the cells in a tree branch no?
longer cells would have more area to bend making them more flexable and the reverse with shorter cells, just a thought...

 

[pancake]

I am working on some winter work research as a southerner working in New England's colder climate, I have most certainly experienced a difference in hinge wood holding power, particularly white pine and all Acer species.

 

[boreality]

I have done extensive research into splitting firewood at -30c. Warmer than that and it splits similar to above 0c but it pops below -30c.

 

[treebing]

-30 C and -30 F are about the same. that is cold.

 

[Tom Dunlap]

The best way to do this sort of research is to split wood or go winter camping in sub-zero weather. Then you have lots of comparisons over lots of temperature ranges.

Moisture content is the key. Dry wood acts the same no matter what the temperature. there is no such thing as absolutely oven dry wood though. Woodworkers talk about moisture content of wood. Generally, air dried lumber can only be brought down to around 15% MC. This will depend on ambient humidity too. the colder the air the less water that will be held. So...the longer the air is cold the drier it will be.

Wood is a good insulator so it would take a long time at low temps to change the brittleness of the wood. Going from 60 to 30 overnight wouldn't change the wood that much. From my experiences the air temp needs to be under zero F for some time before the green wood changes. Is that what you've found Taylor?

 

[Blinky]

I don't have the data to back it up but my understanding is that the yield strength of wood increases as it gets colder but elasticity decreases, that is, the force necessary to initiate failure goes up as temp goes down but less additional energy is required to cause total failure.

So, it's stronger AND brittler.

Like I said though, I can't find the info where I read that.

I haven't really changed my climbing habits in cold weather so far... but then, a really cold climbing day for me is 20F.

 

[Jamin_Mayer]

A lot of good information guys. Right on!

So, it sounds like I (we) really don't have to worry much when climbing in the winter then. After all, I won't be climbing in temps below zero F.

I'll still use caution when there is snow on my boots and on the branches.

And for all of you southern state dwellers...You guys are lucky bastids.

 

[Colin]

Yeah, until Jun, July and Aug.