Cold Hardiness in Trees: A Mini Review

Cold Hardiness in Trees: A Mini-Review
Michael Wisniewski1, Annette Nassuth and Rajeev Arora

https://www.frontiersin.org/articles/10.3389/fpls.2018.01394/full

It may be that you can freely get a PDF, I didn't try.

For me, the gist of this review is that they (scientists) are nowhere near understanding cold hardiness in plants (cold being, temperatures allow for water to freeze).  What this paper gives you, is some keywords to look for, and some references.  It seems that a textbook by Frank in 1985 is a key book to have in understanding this kind of thing.  It is referenced in the article (it is 210 pages I believe).

This URL, gives you the complete article to read.

That article is from Sep 2018.

I found another article, which I will post title, author and URL to.

I am NOT a biology person, I am trained in Materials Science and Engineering.  My M.Eng. thesis (1986) was on simulating grain growth in solids, which shares a lot with freezing of solids (both are nucleation and growth dominated).

If one just considers water that is "almost pure", there are two effects of interest.  The first is something most people know, and that is that there is a positive change in molar volume for water on freezing.  Which is atypical, most materials experience a decrease in volume on freezing.  The other is that the nucleation and growth of ice in water is driven by surface energy considerations in the solid phase (ice).  Small concentrations of solutes near the solid/liquid interface can have large affects on surface energy.

Some ice crystals form sharply pointed solid ice, which can damage things like cell walls.  Other ice crystals have more uniform curvature (positive or negative) as a function of position, and tend to form equi-axed solid water (ice), which has much smaller ability to damage cell walls.  In plants, the first thing one thinks of in terms of "anti-freeze" are sugars, and then maybe sugar-alcohols.

Effects of environmental factors and management practices on microclimate, winter physiology, and frost resistance in trees
Guillaume Charrier, Jérôme Ngao, Marc Saudreau and Thierry Améglio

Apr 2015

https://www.frontiersin.org/articles/10.3389/fpls.2015.00259/full

All the authors are from central Europe (Austria, France).

A little more practical article for me.  I think it would help these authors to go visit some place that gets cold in winter (Siberia, the Canadian Prairies, southern Chile).  For me, the obvious thing that is missing is Foehn winds; there is no mention of Foehn winds (or as I know them, chinooks) in this article.

I think this is a more useful article for most people who live where freezing can happen.  But, I think the authors lack experience for where things get really cold.  They seem to think that snow will prevent freezing in the soil, or it just gets a little cold in the soil.  When I moved to Dawson Creek in 1975, we could actually see 2 or more weeks of winter where the warmest temperature on any given day was below -40.  Some people talk about "frost lines" of 4 feet and think they are a bother.  The frost line here, at that time, was 9 feet (I still think it is defined to be 9 feet, but that is another problem).

The authors also talk about the bark of a tree as having thermal inertia.  I don't think of thermal inertia, I think of thermal mass; but I think the two concepts are closely related.  But no, I would never say that the bark of a tree provides significant thermal mass to the interior of a tree.

I should try to read this at least once more.