Trees in Winter: Wild Winter Weather & Trees

Here we go with another round of wacky winter in Southwestern Ontario. Temperatures hovered below -20 C most of last week and have soared to 12 C today. We got a good dump of snow on Sunday night, but by late Monday, that snow was quickly washing away. Yesterday’s thunderstorms (thunderstorms in January?!) erased most of the last of the snow and now our balmy weather has me in mind of Spring. Watch out though, as starting tonight the rain is going to turn back into snow and temperatures will again dip below -10 C. Crazy!

It is hard enough for us to process the extreme changes in weather patterns, but think about the other things affected by Mother Nature’s weather whims. What are the animals doing? Have the trees even noticed? You bet they have. I am pretty sure everyone and everything has. How exactly do trees cope with winter weather though?

Wild Winter Weather in London, Ontario

Trees in Winter

• In good news, when temperatures drop below freezing insects are at risk of dying. This equates to a reduction in the probability of insect infestations in the coming growth season.
• More good news is that most trees in winter go dormant, therefore flooding is less of an issue for them. Most trees can tolerate 1-4 months of flooding during dormant seasons. Also, the colder water found in winter flooding holds more oxygen, hence is ultimately less taxing on oxygen-loving trees
• The bad news is that trees are very intolerant of fluctuating temperatures. When temperatures rise, trees are at risk of coming out of dormancy too early. Last winter’s warm spell in March was a perfect example of that. Trees and shrubs budded and bloomed, but the subsequent frosts killed all the early flowers. The effect was a huge loss on those tree’s fruit production later in the season.
• Fluctuating temperatures also cause conditions like frost crack. Frost crack happens when there is a significant difference in temperatures, like on a sunny winter day that turn into a cold night. There is stress between the outer bark and inner tree, causing a crack to form. The only good news to that is that most trees can easily repair this damage in the coming growth season, although that area will be vulnerable for a time.
• During the winter, a tree’s branches and twigs become more brittle and susceptible to breaking. When a winter storm hits, a tree’s branches are assaulted by wind, ice, heavy snow and more, often leading to lost limbs. One way to minimize damage is by pruning weak or damaged branches once the tree has gone dormant, but before a storm can do too much damage.
•  A tree’s roots are also susceptible to damage in cold weather. Shallow-rooted trees, container-grown species and newly planted trees can all be damaged during long spells of freezing temperatures. Frozen roots may lead to a tree wilting and going into decline once the growth season begins again. As a prevention, a layer of mulch, leaf litter or snow cover will help to insulate a tree’s roots against the risk of freezing.

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Hold on tight London! Winter is not done with us yet!