The Migrating Maple

Why you’re eating Canuck syrup.

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A sugar maple tree

Lately, sugar maples have become the polar bears of trees. Their unbeatable fall color and delicious syrup have always given the trees iconic status, but now, like the bears, they’re objects of sympathy. As with the bears, their habitat is shrinking as winters grow warmer.

This particular story about sugar maples begins with the bad migraines Thomas Jefferson was having the spring of 1791. A bit of a leap, but stick with me.

That spring, Jefferson was working in Philadelphia, then our capital, as secretary of state in the Washington administration.

Jefferson didn’t like the city—crowded, noisy, dirty—and he didn’t much like the job either. Treasury Secretary Alexander Hamilton was getting on his nerves. Noise plus Hamilton may have actually caused the migraines. Or the migraines, on top of the other factors, might have tipped the scale, making Jefferson desperate for a vacation.

In any case, Jefferson and his fellow Virginian James Madison, then a member of Congress, decided to up and travel north for a month—to Vermont and back.

There we begin to see the maple connection. In a charming and informative article about this Jefferson-Madison pre-presidency spring break, historian Willard Sterne Randall wrote in American Heritage magazine that Jefferson “had come to think of the new state as the frontier ideal, a sort of unspoiled Virginia without slavery or entrenched tidewater aristocrats.”

Jefferson hoped that the yeoman farmers of that unspoiled state could save the nation from depending on sugar grown in the British Caribbean using slave labor. The solution? Maple sugar.

Jefferson was not exactly without sin in the matter of slavery, but he particularly liked the idea that maple sugar would be produced by free citizens living on family farms. Toward the end of his visit, the future president concluded a stirring speech in Bennington by saying, “Attention to our sugar orchards is essentially necessary to secure the independence of our country.”

The year before his Vermont trip, Jefferson, never averse to horticultural experimentation, asked his son-in-law to plant some maples to create his own sugar orchard at Monticello. Historian Randall writes that the trees failed to thrive because they were planted in the wrong spot.

Actually, the wrong spot was Virginia itself, where the winters are too short. Sugar maples evolved to do well in the northeastern United States and eastern Canada. Jugs of syrup with Monticello on the label were never to be.

Some 200 years after Jefferson’s attempt, Burlington feels more like Charlottesville than it used to, and more and more maple syrup labels say “Made in Canada.”

Still, it was a pretty good idea for 18th- and 19th-century New England. Randall notes that Americans in those early days commonly drank as many as 15 cups of tea per day, and they liked it sweet. Jefferson believed that Vermont could produce enough maple sugar to meet domestic needs and even export some, competing with British sugar. Jefferson rarely missed an opportunity to annoy the British.

Here’s why Jefferson’s maple sugar trees didn’t produce well in the 19th century, and why 21st century American maple-sugar makers are losing out. The movement of the sap up the tree and out of the spout and into the pail (or, more recently, into plastic tubing) depends on temperatures that move back and forth across the freezing point in a delicate dance. The best sap flows occur when night temperatures are in the 20s and day temperatures are in the 40s. This normally happens for four to six weeks as the northeastern winter thaws into spring.

With the cold night, the tree absorbs moisture from the ground. When the tree warms up during the day, internal pressure builds and the sap will flow from a tap or even from a broken twig. This productive balance between cold and warm used to occur in Vermont and New Hampshire around the first Tuesday in March. Over the past decade, the right temperature mix has occurred on the average earlier and, more crucially for the economic health of the industry, for a shorter time. The season is over when the nights no longer freeze.

Not only are those crucial times becoming shorter, but sugar maples are moving north. The trees do not get up and walk to Quebec or Ontario when they sense that winters are getting warmer. The existing trees die off; their seeds germinate and do well only in a cooler place. The maple population in general will adjust its range and we’ll see a very slow shift in the mix of northeastern trees.

Like Jefferson, we have a pleasing fantasy of the yeoman maple-tapper—a sturdy New Englander right off the picture on the syrup tin, in red and black plaid, driving his horse-drawn sled. (And not speaking French with a Quebec accent.) He’s very patient, our ideal maple producer, because it takes 20 to 40 gallons of sap to yield one gallon of syrup. To produce 30 gallons of syrup you need the output of 65 mature trees, according to the Cornell Sugar Maple Research and Extension Program.

As spring comes ever earlier, it’s getting harder to keep those mature sugar maples happy. The tree atlas of the U.S. Forest Service predicts that oaks and other trees tolerant of a wider range of temperatures will replace sugar maples as the dominant New England forest tree. Autumn foliage may be a monkish dark brown instead of the breathtaking red and orange and yellow of the sugar maple.

Toward the end of his trip, circling back to Philadelphia, Jefferson shopped for trees at a nursery in Flushing, N.Y. Undaunted, he bought 60 maples for Monticello. They died.

We never did get over our love of cane sugar, but Jefferson would have been pleased to see that for most of the 20th century, the Northeast produced 80 percent of the maple syrup in the world. Now the figure is 20 percent. We’re losing our sugar orchards and, Jefferson would say, we have failed to secure the independence of our country.

There is an International Maple Syrup Institute, a nonprofit group of Canadian and American producers. Any day I bet it will be dominated by those darned Canadians, flaunting their maple leaf flag. The syrup institute will begin to behave like OPEC, threatening to bring us to our knees. Soon we’ll be dependent on foreign syrup.

Note: It’s not widely appreciated that sugar maples have a yellow-green finely textured flower that comes before the leaves. Should you live in or visit the Northeast in March and April, you’ll see a mist of chartreuse in the forest. Appreciate it while the trees are still on U.S. soil.