Notes from the Naturalist - Week 27


Every season has some sort of indicator of change. Warmer days. Fall leaves. Snow. Maple Syrup! In spring fashion today, we celebrated the changing of the winter season, welcoming spring and the sweet taste of Maple Syrup. The weather obviously had a mixed opinion about the changes that are upon us as we watched rain and snow both fall from the sky today. But warm within the lodge we mixed up a batch of waffles and ate them with local Maple Syrup!

We counted all the way up to 40 today! Forty is the number of sap gallons it takes to make one gallon of maple syrup. The children were introduced to several types of spiles or spouts that are “tapped” into trees allowing sap to flow out and collect into a bucket. We looked at a metal bucket and at plastic tubing.  All of the children helped out with the task of mixing and making waffles and they waited so patiently that when the time came for them to eat, they were so very still and quiet!  I am not sure we have ever been that quiet for an extended period of time. They savored every bit of the experience before them!  

“All trees photosynthesize during the growing season and produce sugars to use for growth. In the fall, when trees stop growing, excess sugars are stored for the following spring. Some of those sugars are stored in the tree’s trunk in what are called rays.”

“If you look at the stump of a tree, you’ll see rings of wood. Perpendicular to the rings, rays of cells run from the center of the tree to the bark. These rays consist of living cells that hold sugars that trees use for building new cells and repairing damage from a nail or woodpecker hole. These rays are the source of the sugar for maple syrup.”

“And, the cell configuration in sugar maples is just right to allow sap to flow in the spring. You can tap other species and boil down their sap, but you will not get very much syrup. As it is, the ratio of sap to syrup for a sugar maple is 40:1, so it takes 10 gallons of sap to make a quart of syrup. For a birch, the ratio is 80:1. So tapping sugar maples is the most productive.”

“Physics is what makes the sap run. Nights with temperatures below freezing followed by days with temperatures in the 40s to 50s make sap flow. These conditions occurred in January 2012, and February of this year, but in past years didn’t happen until March or April. The freeze-thaw cycle causes a change in pressure, which forces the sap to move. At night, when the temperature cools, gases dissolve into the sap fluid, causing a decrease in pressure in those cells. The fluid in the wood freezes, compressing the gases in ice. As the temperature increases the next day, the ice melts, the sap warms and the gases expand, forcing the sap to run out of the tree and into the collecting bucket. If the temperatures remain below freezing during the day or well above freezing at night, those pressure differences will not occur and the sap will not flow.”

“The boiling is where chemistry is important. As the sap boils, pure water evaporates and the sucrose concentrates. During the boiling, foam must be skimmed from the surface every few minutes. The foam is the product of a chemical reaction that occurs as the sap heats. The cooking also causes minerals in the sap to precipitate as solids. This precipitate is commonly called niter. It is harmless but somewhat gritty and not very pleasant to eat. It consists largely of potassium, calcium, silica, magnesium, sodium and some other minerals that occur naturally dissolved in the fluid in trees. The skimming of the foam as the sap cooks reduces the amount of niter in the end product. The minerals stick to the organic compounds that make up the foam.”

“You know the season is over when the syrup begins to taste like an old shoe. This happens when the trees start to use sucrose for growth and other compounds become dominant in the sap. When this happens, it’s time to put away the equipment and start planning the garden.”-

With our bellies full and warm, we decided to take a hike out in the dreary weather. I’m not sure it ever felt cold, rainy or snowy while we were outside today. Each child was so well dressed in their rain and winter gear that it made for perfect conditions to explore and hike. The children have become conditioned to being outside and with that they found their rhythm and stride and hiked straight up to the top of Little Round Top! Quite amazing, right?  We have not been up to the top since before December. The children are so used to their equipment, the cold weather and with an overall positive attitude towards the outside, it’s just part of what they do now!