Welcome to Creature Feature, a biweekly series from the CELT education team highlighting local wildlife. Each week, we will share a short introduction to a local organism that you might encounter in your backyard or on our trails.
This time of year, the forest, fields, and skies are extra busy with preparations for the coming winter. Geese are migrating, chipmunks are stocking up on acorns, and snakes are preparing to retreat to their dens. But animals are not the only ones getting ready. Trees, especially deciduous trees, are busy preparing for the colder days ahead.
Deciduous trees such as maples, oaks, and birches all need to prepare for the colder temperatures, shorter days, and snowfall of the Maine winter. These types of trees have long, outstretched branches and big, broad leaves that are great for collecting sunlight but not well suited for supporting heavy loads of snow. They also need to conserve their resources such as food and water to survive the winter. As the days become shorter with less sunlight and the temperatures begin to drop, deciduous trees begin to go into a state of dormancy.
We became aware of this change as we observe the splendor of a New England autumn in all its colorful glory. Trees, like most other plants, produce food using the sun in a process called photosynthesis. Chlorophyll is the most important photosensitive pigment for the photosynthesis process, and it happens to appear green. As the days grow shorter with less daylight the tree slows down its production of chlorophyll. With less chlorophyll pigment in the leaves, other pigments begin to show through, resulting in the brilliant fall colors we see this time of year.
Large, deciduous tree leaves contain a significant amount of water in their cells. Most of the year leaves rely on tree roots for their water, but prepare for the dry winter ahead trees need to save as much water as possible. The solution? Drop the leaves entirely. Besides, trying to keep their leaves from freezing in the winter would require more energy than a tree can produce that time of year, and too many wide leaves could catch snow and cause branches to break.
But what about the rest of the tree? Deciduous trees still have to protect themselves from the freezing temperatures ahead by making sure their cells are prepared. Throughout the year, trees transfer water into their cells. As the temperature drops, trees move that water from inside the cell to the tiny spaces on the outside in between the cells. This ensures that the water doesn’t burst the cells if it does freeze. Most trees also build up stores of sugars, proteins, and fats, which help lower the freezing point of water and provide a trickle of energy through the winter months.
All these adaptations allow for the tree to conserve as much energy as possible to survive the winter. So next time you are walking in the woods or just admiring a beautiful deciduous tree during the winter months, know that while it might look bare it is very much alive and working hard so it can bloom again in the spring!
—BY LISA GENT, CELT EDUCATION COMMITTEE CHAIR