Winter and Trees: How Do Trees Survive Winter?

In the autumn, deciduous trees begin transforming their leaves into rich reds, oranges, yellows, and even purples. While these colors are stunning to behold, they signal something deeper: internal chemical processes that help keep trees alive during the winter months.

Leaves produce the nutrients that trees to grow and stay alive. This happens inside leaf cells that contain chlorophyll, the pigment that absorbs light energy for photosynthesis. During spring and summer, green chlorophyll is so abundant that it masks other, underlying pigments, called carotenoids.

As autumn sets in, shorter days and cooler temperatures prompt trees to form a corky abscission layer where the leaf connects to the stem, cutting off the leaf’s supply lines. With this support gone, chlorophyll begins to degrade. As the leaf dies and the green pigment fades, previously hidden yellow, orange, and red carotenoid pigments shine through, producing the fall foliage we know and love.

As time passes, those leaves eventually fall, providing a range of environmental benefits — including creating a protective layer for insects and infusing nutrients into the soil as they break down. Dropping leaves also helps conserve energy and resources for the winter. Without their leaves, deciduous trees can go dormant, helping them survive until the spring. 

From pine to spruce, many evergreen trees are considered traditional holiday trees — especially among those who celebrate Christmas. And no wonder: their vibrant greenery stands out in otherwise snow covered landscapes

But why do they remain green when other types of trees change color and lose their leaves? The key is: evergreens do lose their needles, just not all at once. In late spring and early summer, fresh evergreen needles appear as lighter green growth at the tips of branches.

Although they stay green during the winter, they aren't actively growing. According to University of Minnesota forest researcher Kyle Gill, in an interview with Minnesota Public Radio, they enter a state that's similar to dormancy. Evergreen needles do function minimally during the winter, yet the trees' overall activities are slowed significantly.

Evergreen needles are also well adapted for cold weather. Their tough, waxy coating and narrow, conifer shape help prevent moisture loss and protect them from freezing temperatures.

Bark functions as a tree’s natural insulation system, protecting it when temperatures plummet. Much like the thick winter coat you rely on in bitter cold, it helps reduce heat loss and shields the tree against harsh conditions.

Beneath this tough exterior lies living tissue — the phloem and cambium layers — that are highly vulnerable to freezing. Bark helps protect these tissues not only from extreme cold, but from physical damage such as insects and disease.

Bark varies widely in thickness, texture, and density between tree species, and these traits often reflect the environment the tree evolved in. Thick, furrowed bark can provide better insulation, while lighter-colored or reflective bark may help prevent temperature-related stress such as sunscald and frost crack by moderating temperature shifts. These adaptations help trees cope with and survive prolonged winter conditions.