It’s that time of year again, when New Hampshirites head into the woods to make syrup from the sap of their box elders, Norway maples and black birch trees.
What’s that you say – nobody taps those species?
That’s not entirely true, as anybody knows who has sipped birch beer, but for all practical purposes you’re right. When it comes to making syrup from sap, the sugar maple has been the overwhelming choice of people in the Northeast for centuries, since the practice began long before Europeans arrived here.
But why? As we prepare to celebrate Maple Syrup Weekend in New Hampshire, why do we ignore all these other species in the woods that are perfectly happy to ooze sap into our buckets, limiting ourselves to just one type of tree?
Simple, said Stephen Childs, a New York State maple specialist. (I called him to get an out-of-state perspective, just in case it might be different.)
He ticked off the sugar maple’s advantages: “It has the highest sugar content, compared to other maple trees under the same growth. It has the latest bud break, so that it stays active the longest. And it’s very common.”
That first point, the sugar content, is key. You’ve probably heard the rule of thumb that it takes 40 gallons of maple sap to make a gallon of maple syrup, which is roughly true. That sounds grossly inefficient, but with other species it’s worse.
Most of the work in making syrup involves carefully boiling away, or straining away through reverse osmosis, most of the water in that sap to create a properly sweet product. Less sugar in the sap means you have to do more boiling, which is expensive and time-consuming.
Birch, for example, can be tapped for syrup, but birch sap is much less sweet than sugar maple sap, by a factor of eight or so. “You need a couple hundred gallons to boil off to get a gallon of syrup,” said Childs.
Still, birch does get tapped sometimes, but for different reasons. Birch has a slightly different sugar – more fructose and less sucrose – than maple. “As it gets toward finishing it really darkens and produces strong flavors. It is used as a flavor ingredient for the most part; you’d hardly ever consider pouring it on pancakes,” he said.
(Incidentally, sugar content of sap is measured in something called Brix, which sounds like a breakfast cereal but is actually the percentage by weight of sucrose in pure water solution.)
Later bud break, the time when trees start to bud out, is also an important benefit for sugar maples, because the appearance of buds makes changes in the chemistry of sap so that it’s no longer good for syrup.
But surely there’s more to the success of sugar maples than their superior production abilities, I thought. Maple syrup tastes awesome – it must have some secret internal ingredient that makes it the best choice, right?
Childs had to think about that for a moment. “It has volatile compounds, some organic acids, a fair amount of minerals – but that’s pretty much true of any maple. You really can’t tell the difference between sugar maples and other maples,” he said.
In a way, this is reassuring because sugar maples are under stress, and not just from climate change.
“In New York, our biggest issue with maple trees is deer. White-tailed deer are just taking out all of the young maple trees – there are no young maple trees in the woods at all,” he said. This is bad: As mature maples age and die, there aren’t enough youngsters to replace them.
“We’re experimenting on doing heavy cuts in the woods, leaving good seed trees, and using the tops and slash (from cut trees) to build huge walls around, to hopefully keep the deer out for six to seven years,” until seedlings are big enough to survive deer foraging.
And when he talks about this “slash fencing” being huge – slash being a term for branches and wood left over from logging because it isn’t commercially viable – he does mean huge. “These are 10 to 15 feet high, 10 to 15 feet wide, and tight. We’ve tried other kinds of fencing with very little success,” he said.
So maybe we’d better make sure to enjoy our sugar maples while we can.
Pass the syrup!
(David Brooks can be reached at 369-3313, dbrooks@cmonitor.com or on Twitter @GraniteGeek.)