What’s so special about sugar maples?

Its only the beginning of Februrary, but all our trees are tapped, our lines are (mostly) repaired and we are only a few projects away from being ready for sugar season. As the trees lie dormant in the woods just before the season, its often hard to believe that in a few short weeks, a massive amount of sap will be flowing down the hill. People unacquainted with sugaring are often taken aback by the fire hose like blast of sap pouring into our tanks during the height of the season. I’ll be honest: the vacuum technology that exists in a modern sugar bush definitely does a lot to improve how much sap we are able to harvest. But, the real magic starts within the sugar maple itself, and is what makes all the rest possible.

There are two characteristics unique to sugar maples that make them ideal for making syrup. First, maple sap is particularly sweet. Well, its not that sweet– sap is only about 2% sugar on average and its flavor straight out of the tree is mostly watery and not maple-y at all. But compared to other hardwood trees like birch, with sap at only about .5%-1% sugar, maple sap is like candy.  While it takes about 40 gallons of maple sap to make 1 gallon of syrup, it would take 80 to 160 gallons of birch sap to do the same.

The second thing that makes sugar maples such a catch is the volume of sap that spurts out of each tiny tap hole over the course of the season. The massive sap flow within the sugar maple is made possible by their unique physiology. Just underneath the bark of a maple tree is a thin layer of sap wood that acts a lot like plumbing in a house, piping water and sugar up and down throughout the tree. When temperatures rise above freezing in the spring, starches stored over winter in the trees roots flows up to the branches through the sap wood to facilitate new growth. This is common to all northern deciduous trees.  In sugar maples, unlike most other trees, the cells between and around the sap wood are filled with carbon dioxide rather than water. Stay with me here, it will all make sense, I promise. When temperatures drop below freezing at night, the CO2 cells around the sap wood contract (rather than expand, like they would if they were filled with water). This creates negative pressure within the tree as it freezes, drawing sugary sap up from the roots. The next morning, as the tree warms, the CO2 filled cells expand and create a positive pressure within the sap wood. This causes sap to move up the tree towards new growth or, if you’ve drilled a tap hole into the sap wood like we do,  out of the tree and into your bucket or tubing.

After that, the tree’s work is done, and its up to us to transform a tank full of watery sap into a bottle of syrup!

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