East of Ely - Antifreeze for the Soul

by David Krikorian

Maple syrup tapping comes late to Northeast Minnesota, but the sap flows as well as it does in New England. I partook in this annual gathering over the years that I lived along Lake Superior, loving every minute despite long hours of jug tending and fueling the everlasting fire that distilled sap water in an old tub into dark golden syrup.
This ritual bridged the gap between late winter and early spring with friends and family, beginning each day as the sun cast its first light and heat that pumped the forest to life with drum rolls from mating woodpeckers knocking their brains out.
Little did we realize how our syrup making ritual was tied into an adaptation that enabled these hardwoods to survive the harsh winter of the northwoods.
I learned this only recently, and will try to explain how it works, avoiding terms like phenotypic plasticity and other concepts best left to scientists. My search opened a story that began 250 million years ago, when Earth’s early forests sprang up over tropical regions, while colder latitudes remained barren. Back then, evergreens and deciduous trees had yet to adapt to cold, but this was slowly about to change.
The tropics provided trees with warmth and water that never froze, saving plants from frost damage where water freezes into jagged crystals that cut through cell walls (picture the slimy limp leaves of tomato plant the day after being kissed by Jack Frost in June).
Split a tree open from top to bottom and you’ll discover a living pump that sucks water and nutrients up from the ground to the outermost leaves. Whenever drought occurred in those warmer regions, the trees’ pumps had to work harder to suck up moisture, often creating bubbles from air pulled in from outside the roots. The air bubbles block the upward flow of water the same way a clot or air bubble can clog a human artery.
Trees adapted to the problem by narrowing these pipes, spiking the pumping pressure, helping the inner tree structure to force liquid upward, bubbles or no bubbles. This adaptation had another unseen benefit because it also enabled trees to move into colder regions, since they were already able to accommodate the slow pressure of near-frozen water.
Next came the problem of dealing with the leaf clusters that grow on deciduous trees, creating the potential for a perfect storm of frozen plant cells. To prevent this, the leaves have to drop off and then regenerate in spring for trees to survive, a simple process, yet the trick lies in the detail of what happens before the leaves fall. The photosynthesis that occurs in deciduous trees is an exquisite process of turning carbon dioxide into food with a popular byproduct, oxygen, so critical to life that it becomes easy to overlook the more important thing happening here. You see, just before the leaves drop, trees absorb all the sugar from the leaves needed to survive the winter, but with many more benefits meant to keep life in motion.
The keyword is carbon, which is converted by photosynthesis into carbohydrates stored as starch that converts into the primary food for trees like Sugar Maples, and other leaf bearing species. That same sugary substance produced by leaves is called glycol, also the main ingredient of antifreeze and very effective at keeping water from freezing even at temperatures less than -20º Fahrenheit.
Evergreens, for example, have no need to shed leaves (needles) because these trees are very efficient at maintaining a super-high ratio of glycol/antifreeze to water, keeping the needles from freezing solid all winter long. But I imagine pine syrup on pancakes must be as tasty as drinking turpentine.
Deciduous trees are less efficient at producing sugar, so their leaves make up for the deficit before falling. And of all the leafy tree species, it seems that maples produce sap with a sugar content that tastes just right for all the Goldilockses of the human race.
It takes 40 gallons of sap to distill one gallon of pure maple syrup, while we gather sap, constantly stoking a wood-fired boil that lasts for days. Yes, it’s a lot of work, but then there are moments like watching kids at sunrise sliding like otters over refrozen ice that make this one fine way to nourish the soul.