As you’ve probably seen at some point in your life, trees do not disappear in the same way that flowers or flora might in the winter. They may lose their leaves, but there is a chance that does not even happen if the tree is an evergreen. So, how do deciduous trees survive the winter?
Trees can generally survive temperatures as low as 30°f – 40°f during the winter. Tree’s shed their leaves in the Fall to reduce winter water loss while excess snow is available. Trees also slowly dehydrate themselves in the summer to expunge excess water, which would cause the tree to burst.
Before we go deeper into the methods that trees may utilize, we should take some time to first discuss the question in a general sense: how is it that trees can avoid freezing? Follow along, and we’ll get straight to the good part!
How Do Trees Not Freeze?
Trees are some of the most prevalent, sturdy plants that span the planet. So how is it that they can manage to not only survive the winter months in places with temperatures dropping well below freezing but thrive in those environments?
Trees are adaptable but will only grow to maturity in places that can sustain their species.
Here is a most-asked question about trees and their ability to survive the winter:
What Do Trees Need To Get Ready For Winter?
Whether adjusting cold tolerance on a cellular level, dropping leaves, or keeping needles, and allowing the bark to become the protector it was meant to be; trees go through many processes to prepare for the winter.
All trees are different, but the basic biology that drives them is what allows them to be both resilient and flexible organisms, especially during extremely cold temperatures.
4 Ways That Trees Can Survive In The Cold
OK – now we are really getting into the good part here!
Here are a few ways that trees are able to survive in the cold and winter. Of course, these methods may not be the exact practices that every single tree uses, nor do they ensure 100% that a tree will survive. However, when it comes to resilience, these are huge players.
Mulch Protects Tree Roots in The Winter
Topping our list is the least natural of methods because it is one that involves human assistance. That’s right; you can play a pretty sizeable role in protecting your plants during those cold winter months!
Root injury is one of the winter effects that begin at the base of a tree and work their way through the body of the entire individual, leading to severe damage or even the death of the tree.
You can help your tree to avoid root injury by using a few methods to cover the roots.
For instance, winter mulch can help to reduce winter tree root injury. You’ll want to start by covering the roots of your not-quite-mature tree, especially any newly planted trees or shrubs, with a few inches of shredded mulch. About the width of your hand should do the trick.
You’ll then want to place the mulch in a circular pattern around the tree and then pull the mulch about 1/2ft away from the base of the tree. This will ensure that any stray roots will not be subject to freezing temperatures.
If there are any cracks in the soil around your tree as you are completing this first step, you’ll want to make sure that they are filled in with new soil before you move on.
Next, you will want to consider what the fall weather has been like in your area.
Has it been dry? Make sure to water the soil (and mulch) around your tree before the first frost, so there is not any possibility of frost that would result from dry soil soaking up moisture that hardens into an icy layer once underground.
If the Fall had a decent level of rainfall, that last step is NOT something you will have to take into consideration.
Tree Bark Insulates The Inside of The Tree
Tree bark does more than just indicate what type of a tree you may be looking at or dealing with; its benefits go far beyond the qualitative, descriptive uses that it can serve.
The bark of a tree is a great insulator and acts as more than just an outer layer. The bark of a tree is essentially like a jacket, a natural fence to deter animals from getting too close to the trunk itself, and helps the tree to regulate its internal temperature.
In the hot months of summer, the insulation works well to reflect light and disperse heat in a way that acts to cool the majority of the tree down. From roots to limbs, and the entire truck in between, the temperature of the tree is able to be well-regulated.
This effect is reversed in the cold winter months, and the tree is able to regulate itself in a new way. Instead of cooling down, the insulating properties of the bark help the tree to warm itself up.
The ‘body heat,’ so to speak, remains trapped below the bark, and the tree is protected against cracking and freezing that would otherwise be caused by the cold.
Different species of trees will have different types of bark. For example, a tree that typically thrives in a more temperate environment might have bark that is thinner or less ridged because it needs fewer barriers of protection against the elements. Even something as seemingly simple as the color might be changed in the shade, depending on how much light a tree needs to be reflecting based on its specific environment.
The thicker, darker, and more ridged the bark, the better its host tree will be at heating quickly in the dead of winter. Because darker colors absorb the heat from sunlight, dark bark is often an indicator that a tree will do particularly well in snowy, windy, or just plain frigid weather.
Reversely, white bark is an adaptation of a tree that helps protect individuals against sun damage. So, during the darker, the more adaptable to frosty temperatures, the lighter, the better in warm, open, sunny spaces.
Bark plays so many complex roles in the ability of a tree to not only survive but thrive. Is it truly the first and main line of defense against the elements no matter what type of environment a tree is located in.
Losing Leaves Reduces Tree Water Loss During Winter
The next natural factor in a tree’s ability to do well in frigid temperatures focuses on a different section of the organism altogether. We move up beyond the roots, past the trunk, and up to the canopy itself.
Whether a tree has leaves that fall off to prepare for the cold, a deciduous tree, or it has needles that brave the winter, an evergreen, depends on the species itself. Not only that, but it also has to do with many external factors that species have had to adapt to overtime.
Have you ever wondered why deciduous trees lose their leaves in preparation for winter? This is an annual process that most are likely familiar with, regardless of region, if you live somewhere in North America. However, the reasoning behind this process is less commonly known.
Deciduous trees lose their leaves during the autumn season in order to reduce water loss. In the same way that animals store up extra fat to prepare for the cold of winter and reduction of food sources, trees prepare to retain water while there is an increase in snow and ice but a lack of the rainwater that trees absorb best.
Evergreen trees, however, are a different story. Most conifers, which are the evergreen trees with needles and the kind of evergreen tree that would exist in a place that faces freezing temperatures, retain their needles throughout the entire year.
Conifers overall are vastly stronger than hardwoods, which helps them to survive the winter. According to Michigan State Extension, conifers can withstand up to 900 psi, which allows them to absorb ice expansion. This is more than the psi than what gets released from a CO2 tank.
While there are some exceptions, conifers don’t lose their needles because they are better equipped to retain water. Thanks to their smaller surface than broad leaves and the waxy coating that protects each needle, water loss due to transpiration and evaporation is able to be extremely limited.
Even the exceptions to this rule of not losing needles only extend to trees that will shed some old or damaged needles. Overall, conifers keep their needles all year round.
In the same way that bark is a protector of the main body of a tree, leaves have a lot to do with water retention and protecting the life force of the tree.
If you’re interested in learning more about conifers (an evergreen tree), take a look at our piece on the trees that keep their leaves all year.
Trees Dehydrate Themselves To Avoid Water Freezing During Winter
For a tree, the process of adjusting for cold tolerance takes place at the cellular level. This ultimately means that trees actually start preparing in the late summer period in order to be fully ready by the time winter hits. As daylight dwindles and resources begin to lessen, a tree will enter a dormant state.
In the same way that it works for many animals that hibernate, the dormant state really just allows a tree to reach a higher level of adaptability and tolerance for weather and other environmental factors that are not exactly begetting of natural flourishing.
Essentially, the tree will begin to slowly dehydrate itself to avoid having too much water inside when the temperature drops. The same theory here applies to when you are winterizing a boat. If the lines aren’t being used and water is in them, the pipes (cells of the tree) will freeze and crack.
Freezing of cells ultimately results in damage to living cells, so it is a huge priority for trees to avoid this sort of detrimental winter outcome. In the winter, these cells become extremely brittle, as the tree has far less water in it than at peak form during the summer.
Remember, the tree is in a survival hibernation state and not undergoing maximum photosynthesis.
What Happens When It Is Just Too Cold For A Tree?
All plants have limitations, and defoliation or the loss of leaves due to either chemicals or natural causes is one factor that limits the overall growth of a tree from that point forward.
This chain reaction goes to show that trees are complex organisms that work in a harmonious system which, when disturbed, can have disastrous consequences. A weak tree is less able to protect itself by fighting disease, braving a cold winter, or adapting to other unforeseen circumstances that may challenge its vitality.
What exactly happens in these sorts of situations when it is just too cold for a tree to thrive?
Well, all species on earth, including trees and other plant life, have a minimum temperature at which they can thrive. Once this range of low temperatures is met, when the limit itself is passed, the thermal requirements of the organism are no longer being met, and it is not able to survive any longer, much less thrive.
How does this manifest, though? What are the results of a tree that cannot survive the winter, and how do they indicate that this may be the end of its lifespan?
A quick note, if you’re interested in the lifespan of trees, you can check out our piece on the lifespan of common oak trees here.
Tree Limbs May Bend Or Break in Winter
The results don’t always necessarily have to be detrimental; sometimes, the impact of a winter that is too cold for a tree to handle can have a relatively benign outcome.
Limbs may bend as a result of a combination of wind, sub-zero temperatures, and subsequent re-thawing. Often, bending of limbs doesn’t cause too great an impairment, but in cases where limbs thaw too quickly, or the wind does not let up, they may break off entirely.
It is much more likely and common for a branch or two to bend or snap than it is for a tree to bend at the base. However, it depends on the maturity of the tree- how thick the trunk really is, how stable of a root system it has, and other combinations of factors both internally and externally.
Tree Sap Can Cause a Tree to Explode in Winter
Tree sap is the ultimate life force of a tree, more so than the water or the nutrients that sustain this internal liquid gold.
So, when a tree does not have enough time to acclimate or some of these other defenses against the elements fail, it’s the sap that is at risk and can cause quite the commotion as it is impacted.
If the sap begins to freeze, the water in it begins to expand and, when this occurs in a large enough scale of a situation, it could quite literally cause the tree itself to break apart and explode.
Remember the scenario we talked about where trees expunge water and dehydrate themselves in preparation for the winter? Well, this is a similar phenomenon.
Essentially, like pipes bursting, if the sap of the tree freezes and expands, and will cause the tree to quite literally explode and shred the overhydrated portion of the tree. Most commonly, this happens on a large branch or limb.
While partial freezing of a tree is not all that uncommon, it can happen.
That’s All For Now!
Well, that’s pretty much all for now.
Remember these four ways that trees can survive the winter, along with some outcomes to expect in less-forgiving climates and scenarios.
It might be confusing to know that some plants cannot survive the cold, while others brave it like champs, but trees are strong steady, resilient organisms. If all else fails, keep in mind these four ways that trees can survive the winter months:
- Mulch and Soil Protect Tree Roots in The Winter
- Tree Bark Insulates The Inside of The Tree
- Losing Leaves Reduces Tree Water Loss During Winter
- Trees Dehydrate Themselves To Avoid Water Freezing During Winter
But again, there are always outliers. Sometimes the cold is just too cold, or the wind gets too strong, or any other combination of elements ends in a premature ending of a tree’s life.
Nature follows rules, but it also likes to break those rules. So, we learn what we can and help when needed, but ultimately it is up to Mother Nature herself to determine when a tree can survive a winter and when it just isn’t quite up to the challenge.
Thank you for reading!
I hope this article helps you understand the way that trees work and brings you just a piece of awe for these incredible plants as you continue along your tree journey!
Essiamah, S., & Eschrich, W. (1985). Changes of starch content in the storage tissues of deciduous trees during winter and spring. IAWA Journal, 6(2), 97-106.
Körner, C., Basler, D., Hoch, G., Kollas, C., Lenz, A., Randin, C. F., … & Zimmermann, N. E. (2016). Where, why and how? Explaining the low‐temperature range limits of temperate tree species. Journal of Ecology, 104(4), 1076-1088.
Piper, F. I., Gundale, M. J., & Fajardo, A. (2015). Extreme defoliation reduces tree growth but not C and N storage in a winter-deciduous species. Annals of botany, 115(7), 1093-1103.