Not in my experience.

I think it does. It always seems that frozen materials, once thawed, tend to decompose fairly quickly. Purely observational though.

Thanks.
I have been trying to find an authoritative answer using web searches. Some sites have mentioned it helps but do not say why or how much or how quickly. My guess is that the freezing and thawing might cause some expanding and contracting and maybe even cracking of matter and maybe even break some cell walls but so far no great answer has been found.

I can't give you an authoritative answer, but I can ask an authoritative question:

Compared to what?

OM breaks down faster in thaws than it does when frozen, but not as fast as it does when it's properly mixed, greens:browns.

This cannot be quantified, of course, because there is no way to standardize the ratio of freeze:thaw, any more than you can standardize the ratio of green:brown.

If your goal is to estimate how long it will take a pile of leaves to break down to compost, based on local weather forecasts, you're doomed to disappointment.

Freezing water breaks pipes, cast iron motor blocks and heads and crumbles granite mountains from moisture getting into cracks etc. then expanding, over time. That is how strong the expansion is, so yeah, if there is water in a piece of matter and it gets cold enough, it will freeze. If there is no place to acomodate the expansion, something is gonna break, split or crack.

I have found that freezing and thawing does a good job of breaking up clods of dirt, and also think that the structure of dead leaves laying on the ground are weakened, if they were wet and froze, but that is not the main thing in the decomposition leaves etc., it is more the microbial or fungal activity.
Bill P.

It's certainly more noticeable on greens than wood. Take a perfectly good piece of lettuce and put it in the freezer for a day. YuK! after that. A piece of wood, though, would probably look and feel the same for many freeze-thaw cycles before it started to break down.

Karen

Lignin and veggies are 2 very different animals. Freezing disrupts cell walls in things like vegetables and fruit so that when they thaw they are mushier and compost quickly. Leaves and wood are much different than that. It just plain doesn't seem to happen to any appreciable degree or I'd lose my uncovered fresh woodpile over the winter.