We started tapping maple trees on campus this week. I would guess that most of my readers are familiar with the general process of making maple syrup – you tap the trees to collect their sap and boil it down to get rid of the excess liquid and concentrate the sugar. The Ojibwa Indians in this area were already collecting sap to make syrup and sugar before the first European settlers arrived, and there’s even a town south of here called “Sugar Camp” because the site was known as a center of maple tapping activity. But why do we tap the trees at a specific time of year? What exactly is going on with the sap?
Two species of maple are common on the property where I live. On the left is a leaf from a sugar maple, Acer saccharum, the common, familiar tree that we tap to make maple syrup each spring, the one that’s on the Canadian flag. On the right is a leaf from a red maple, Acer rubrum. I love that their Latin names actually mean sugar and red – makes them easy to remember. You can easily tell them apart by their leaves if you know what to look for, because sugar maple leaves have nice smooth edges while red maple leaves have coarse teeth. S for sugar maple and smooth, R for red maple and rough! (Click to enlarge the photo if you can’t see what I’m talking about.)
Red maples are much more tolerant of wet habitats that sugar maples, and for this reason we often see them growing around the edges of the bogs.
It’s pretty striking, actually. I took this photo yesterday while walking on a trail that ran along the edge of a bog. The side of the trail facing the bog was lined with red maples and some white pines. The side of the trail away from the bog was all sugar maple and balsam fir. Ecological gradients!
Update: Tom has suggested that the particular tree whose leaf I plucked for my comparison shot may not be a pure red maple after all. See the comments. These tricky trees and their darn gene flow!
Never, ever take sugar maples for granted. Not only do they provide us with a sweet and tasty breakfast condiment, they perform a very cool function called hydraulic lift.
All plants take up water through their roots and evaporate it through their leaves. Sugar maples (along with some other plants) take it a step further. During the day, their roots draw water up from deep underground; at night, when water isn’t evaporating from the leaves, the excess is released into soil near the surface. Sugar maples essentially irrigate the soil around their bases. To read more about this phenomenon, check out this article from Cornell.
So if you like wildflowers, next time you see a sugar maple… tell it thank you.