How Do Trees Survive the Cold?

​During the long winter months, besides snowstorms and high winds, trees face two main challenges, extreme cold and a lack of water. We all learn from a young age that deciduous trees lose their leaves in winter. But why? One of the reasons is that trees with broad leaves lose a lot of moisture and shedding their leaves in fall makes sense as it limits moisture loss during a time when liquid water is scarce.

Why do evergreens keep their leaves? The needles of conifers have less surface area and moisture loss is limited. While most conifers don’t lose all their needles, they do drop older, worn-out needles before the winter. Because conifers retain their needles year-round and do not become dormant the tree is, however, at risk of losing too much water in winter. If the roots of the conifer can’t replace the moisture lost through the needles, the cells will die, and the tree will suffer from what is known as winter kill or winter burn. The advantage for conifers in retaining their needles is that they can continue to photosynthesize all year and they do not have to expend as much energy as deciduous trees to grow new leaves in the spring.

Deciduous trees become dormant in winter. This process is similar to hibernation. When a tree becomes dormant everything, including the tree’s metabolism, energy consumption, and growth, slows down. Because the tree isn’t producing food in the winter, it has no use for its leaves and as the cold weather sets in, the tree produces a chemical called Abscisic acid (ABA) in the terminal buds (the tip of the stem that connects to the leaf) and this causes the leaves to fall off.
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Abscisic acid also prevents tree cells from dividing and halts growth. Impeded growth is part of the dormancy process and enables the tree to save energy and only use their stored energy for essential functions that keep the tree alive rather than wasting it on unnecessary growth. This is similar to animals storing food in the form of fat when they hibernate. It is natural for trees to go through dormancy cycles and if the tree is forced to evade dormancy in a hothouse or other unnatural environment, it will have an adverse impact on the health and lifespan of the tree.

Pruning trees in winter has many advantages and promotes tree health but winter or dormancy pruning is cold, hard work so you might want to consider hiring a professional tree pruning service.

Once all the leaves have fallen off your deciduous trees you will clearly be able to see the trees substructure and growth patterns as well as any dead or dying branches. This makes it easier to identify any structural issues and correct them with a few strategic cuts. The removal of diseased, dying and dead wood in winter will ensure that your tree starts the spring looking healthy and it will prevent the branches from becoming a safety hazard during storms and strong winds. Winter is also the best time to shape and train young trees to grow the way you want them to, eliminating future structural defects.

Winter pruning makes trees bloom better and produce more fruit. When you prune in winter the tree is not placed under any stress and you do not disrupt the trees growth cycle, still allowing it to produce strong new growth in the spring. The correct winter pruning can significantly increase trees’ fruit production.

Contact Martin’s Tree Services for all your winter tree pruning needs.