If you walk the trails this winter, you will see many trees without their leaves. This doesn’t mean that they are dead; they are just our deciduous trees surviving the winter! Texas native trees have evolved to be able to survive in our region and handle both the hot summers and cooler winters. This critical process which trees use to survive the winter is called dormancy.
What is Dormancy?
Dormancy is like a survival mode of trees. In this process, trees slow their growth and conserve their energy to survive the cold temperatures and reduced sunlight hours.
Deciduous Trees
Deciduous trees such as oaks and maples tend to drop their leaves to conserve water and energy. In the winter when trees are unable to absorb as much water from the frozen and solid soil, they drop their leaves to slow the loss of water. These tree species reduce their functions down to the bare minimum to stay healthy over the winter and have high survival rates going into the spring.
Evergreen Trees
Evergreen trees such as pines and yaupon hollies do not go into dormancy like deciduous tree species over the winter. Evergreen trees remain active year-round, but they are slowed down in the winter. Due to their physical characteristics, they can avoid dormancy in the winter months. Evergreens commonly have needles and shrubby foliage, which is easier for the tree to support over the winter because it has a smaller surface area than the deciduous tree leaves. Evergreen trees also have this amazing adaptation called cellular dehydration which moves the water from inside their cells to outside of the cells to form a protective layer. This process allows the tree to continue to function throughout the winter, as it is better protected from the freezing temperatures. Evergreen sap also works like an antifreeze; their sap has a lower freezing point compared to the sap of deciduous trees!
Support our Trees!
Even though the trees are currently working hard to survive the winter, there are actions we can take now so they’ll thrive in the spring. Here are some ways that you can help your trees at home!
- Mulching
- In the winter months, having a layer of mulch one to two inches thick helps insulate the roots and soil against the chilling temperatures. Mulch also retains moisture in the soil around the tree.
- Dormancy Pruning
- In the late fall to winter, you can strengthen and prepare your deciduous trees for the spring bloom by pruning them. Performing thoughtful and careful pruning creates a stronger tree for the spring. Be careful to trim sparingly!
- Wrapping the trees
- Consider wrapping young or newly planted trees with burlap or tree guards to help shield the trees from frost. In our climate, trees can struggle with the warm days and cold nights, and wrapping them helps to protect from these temperature swings.
Supporting our trees through the colder months is incredibly beneficial. By doing so, we increase survival numbers, maintain and elevate native habitats, support our pollinators, and keep our water and air clean!
Interested in learning more?
- How to Know if Your Tree is Dead (Or Just Dormant) – TreePeople
- Pruning Trees and Shrubs With a Purpose – Urban Programs Travis County
- Protecting trees and shrubs in winter | UMN Extension
