Rachael Clark | Tree Education | Feb 10, 2025
Why Your Christmas Tree Doesn’t Fear the Freeze.
Winter brings freezing temperatures and limited liquid water, but coniferous trees like pines and spruces thrive thanks to their incredible evergreen winter adaptations.
Unlike deciduous trees that shed their leaves, conifers retain their needles, resist freezing, and stand strong against snow and wind.
One of the primary survival traits of conifers is their needle structure. Unlike the broad leaves of deciduous trees, evergreen needles have a thick, waxy coating that reduces water loss. This waxy coating also minimizes the risk of freezing, allowing evergreens to retain their needles year-round. As a result, conifers can continue photosynthesis whenever conditions allow, even during the colder months.
Conifers do not enter full dormancy like deciduous trees. Instead, they undergo an acclimation process to prepare for winter. As temperatures drop below 50°F, conifers make cellular changes that help them become more cold-hardy. The goal is to prevent internal freezing, which can damage the cells and cause death.
At sub-zero temperatures, conifers protect themselves by replacing saturated fatty acids in their cell membranes with unsaturated ones. Unsaturated fatty acids have a lower freezing point, which helps keep cells intact when temperatures plummet.
Additionally, conifers draw water out of their cells and store it in spaces between them. This water can freeze without causing cell damage. When external water freezes, it releases a small amount of heat, which helps protect the internal cellular water from freezing.
Dehydration is another significant winter risk for trees. In winter, coniferous trees can lose moisture through their needles faster than their roots can replenish it from the frozen ground. If too much moisture is lost, the tree can suffer from winter burn, where the needles turn brown and the tissue dies off.
Preventing dehydration is key, so conifers have tube structures in their vascular system that help keep water flowing smoothly even in winter. These structures help prevent air bubbles from blocking water transport, ensuring the tree can retain enough moisture to survive the cold.
With the risks of freezing and dehydration reduced, conifers must contend with winter winds and snow accumulations. Luckily, evergreens are equipped to handle these challenges. Their cone-shaped branches help snow slide off rather than accumulating and causing breakage. Fir and spruce trees also have flexible branches, allowing them to bend under heavy snow without snapping.
Additionally, the dense foliage of conifers helps protect them from wind abrasion, reducing moisture loss from harsh winter winds.
Coniferous trees have incredible adaptations that allow them to survive and thrive throughout the winter months. From wax-coated needles to specialized water management and flexible branches, these trees are well-equipped to handle freezing temperatures, dehydration, and heavy snowfall. Next time you see a towering spruce standing stoic in the middle of winter, take a moment to appreciate its remarkable resilience and beauty.
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