How trees survive the cold.
The first official day of winter, December 21, is closing in. While we’ve seen some snow, ice and cold temperatures lately, the Winter Solstice has yet to occur. The Latin origin of the word “Solstice” loosely translates to “the sun standing still”. It is the shortest day and the longest night of the year. In my book, it means get outside and soak up the sun before it’s gone!
Last month’s blog touched on protecting trees from winter damage, by pruning, staking vulnerable trees, mulching and cabling. As the landscape finally settles down into dormancy, I am reminded of all the remarkable ways in which trees and shrubs adapt to the cold of winter. Evergreen Rhododendron is the perfect example. Have you ever noticed a Rhododendron with its leaves drooped downward, even though the leaves are still a healthy green?
The leaf movement is a biological response to cold temperatures. On the underside of the leaves are pores through which the plant loses water and takes up air. The Rhododendron leaves are drooping and curling to prevent water loss and minimize damage from repeated freezing and thawing.
Dormancy is what keeps trees and shrubs alive during the winter. The first stage of dormancy for deciduous trees is leaf loss. They don’t make food during the winter, so they drop leaves to maintain energy. During dormancy, much like hibernating animals, everything slows down. While Evergreen trees don’t lose their needles every fall, they do hunker down, at least internally. In both evergreen and deciduous trees, a chemical chain reaction occurs that tells the tree to stop growing, close its pores, stop sap from flowing and generally close up shop for the season. The whole process is a brilliant cycle of nature that is guided by changes in daylight and temperature.
Here at ArborTech, we still marvel at the sight of a seed sprouting. We are in awe of nature and are humbled by the cyclical processes all around us. Year after year the trees wake up in the spring, flourish in the summer, wind down in the fall and go to sleep in the winter. Simple. Beautiful. Happy Solstice to All!