• UVM researchers develop a way to vastly increase maple production
     | November 10,2013
    Photos by Sally McCay

    Four years ago, Tim Perkins and Abby van den Berg cut the top off a maple tree. As researchers at the University of Vermont’s Proctor Maple Research Center, they wanted to learn more about sap flow.

    Instead, they discovered an entirely new way to make maple syrup.

    “It’s revolutionary in some ways,” says Perkins.

    Their new technique uses tightly spaced plantations of chest-high sugar-maple saplings. These could be single stems with a portion — or all — of the crown removed. Or they could be multiple-stemmed maples, where one stem per tree can be cut each year.

    Either way, the cut stem is covered with a sealed plastic bag. Under the bag, the sap flows out of the stump under vacuum pressure and into a tube. Voilà — huge quantities of sap.

    In short, these plantations can allow maple syrup production in a farm field.

    Typically, a traditional sugarbush produces about 40 gallons of maple syrup per acre of forest by tapping, perhaps, 80 mature trees. With this new method, the UVM researchers estimate that producers could get more than 400 gallons of syrup per acre drawing from about 6,000 saplings.

    The new technique has the potential to enhance business for existing syrup producers, the researchers think, and defend Vermont’s maple industry from threats that range from climate change to spiking land costs to Asian long-horned beetles.

    From the ground up

    “We didn’t set out to develop this system,” says van den Berg. “We were looking at ways to improve vacuum systems.”

    But during a spring thaw the tapped tree, from which they had removed the crown, just kept yielding sap under vacuum pressure. And more sap and more sap.

    “We got to the point where we should have exhausted any water that was in the tree, but the moisture didn’t drop,” says Perkins. “The only explanation was that we were pulling water out of the ground, right up through and out the stem.”

    In other words, the cut tree works like a sugar-filled straw stuck in the ground. To get the maple sugar stored in the trunk, just apply suction.

    While the cut plantation saplings will regrow branches and leaves from side shoots — and can be used year after year — “the top of the tree is really immaterial for sap flow under vacuum-induced flow,” Perkins says.

    “Once we saw that we could get yields without tops, it was — wow! — this changes the basic paradigm,” says van den Berg.

    Large, mature trees are no longer needed to provide the sugar. “It became clear that we could deal with an entirely new framework,” she says.

    Parallel production

    Maple syrup production is a rich part of Vermont’s working landscapes. Some people make it their full-time profession, using hundreds of acres and tens of thousands of taps. Others supplement farm income or other work with smaller sugaring operations.

    At all scales, maple syrup producers face increasing challenges.

    One of the most pressing is the rising cost of land.

    “There is a great deal of expansion in Vermont’s maple syrup industry right now, and forestland prices have gone up a lot,” says Perkins. “This can help those producers who are at the stage where they can’t afford to go out and buy a few million dollars worth of land to be a full-time producer.” But they could add some acres of plantation production — for more syrup with less land.

    “If you are using 10 acres of abandoned farmland or a regenerating forest that you already own, this technique makes a lot of sense,” says van den Berg.

    With lower start-up costs, and quicker expansion (or contraction) of one’s business, “it’s another way to help us maintain the traditional working landscapes of Vermont,” she says, letting people continue to make a living — and remain — on their land.

    The researchers estimate that the cost of production using the plantation technique will be roughly the same as current methods. Though the sap yield per acre is much higher on a plantation than a forest, so, too, are the potential costs of equipment, labor and maintenance.

    “I think you’re going to find sugarmakers who are doing both, standard sugarbush and plantation,” says Perkins.

    Coming threats

    With climate change, this dual approach may become increasingly attractive — even a matter of business survival.

    “If this region is going to warm more — then with a plantation we don’t have to rely as much on strong freeze/thaw cycles” to get sap flowing, Perkins says, “because these smaller trees freeze faster and thaw faster.”

    Any form of maple syrup production relies on freezing temperatures to transform starch in the wood into sugar. But in larger trees, it’s much more important to generate sap pressure from a freeze/thaw cycle, van den Berg says, than in a plantation system with small trees that can rely predominately on vacuum-assisted flow.

    “The spirit of this work is to augment and help out existing producers,” she says. “With a semi-wild harvest you’re always going to have limitations.”

    One of which may be a deadly limitation in the form of an invasive pest. Though Asian long-horned beetles are not currently found in Vermont, they are infesting trees in Ohio, Massachusetts, New York and Ontario. They kill mature maple trees, and so federal and state officials have been vigorously cutting and burning any trees where the beetles are found.

    “This pest likes big trees,” Perkins says. “They don’t like saplings.”

    Jacques Couture, a maple syrup producer in Vermont’s Northeast Kingdom and chairman of the Vermont Maple Sugarmakers Association, sees how this new technique might help producers be more nimble or recover from trouble.

    “One of the really interesting aspects (of the plantation approach) is the possibility to establish some maple syrup production in a much shorter time-span than is the current norm,” he notes.

    “If we had a natural disaster, such as a widespread hurricane or some insect pest, that would wipe out a large percentage of the maple stands,” Couture says, “this might appeal to some who were affected as an alternative way of getting back into production sooner than the normal 40-plus years for trees to grow to tap-able size as we know it today.”

    Plantation saplings could be ready in seven years.

    Another potential advantage of agricultural-style maple plantations is, well — they’re agricultural.

    “We can control the system much better by fertilization and irrigation,” Perkins says. “One of the limiting factors on sap production in the spring is soil moisture. Typically we have enough in Vermont — but during years where it’s a very dry winter we may not have enough,” and that hurts production.

    Unknown outcomes

    Still, despite the potential for more predicable and profitable management of maple sugar operations that plantations might bring, much remains unknown about the implications of this research.

    “It’s too early to make any predictions,” says Eric Sorkin, a producer of organic maple syrup from Cambridge who was briefed on the new project.

    “Any time something comes along which fundamentally undermines the status quo, there will be clear winners and losers — and that is what this could be,” he says. “This could lead to a fundamental shift in the way we make maple syrup, so certainly there will be people who benefit from it.”

    But just who benefits is hard to say, and many other changes are afoot in the industry and the world that make the impact of plantations hard to foresee.

    “I don’t think there will be a sudden shift; the life cycle doesn’t permit it,” Sorkin says.

    But if over the next 20, 30 or 40 years, the plantation technique is combined with efforts to select seedlings with improved “sweetness” (that is, the amount of sugar they yield) or faster growth, this could give plantation syrup a distinct market advantage.

    “If you can grow these sweet trees that have twice the sugar content, then your price of production drops in half,” Perkins says. “In 20 or 40 years from now this method could be considerably less expensive than the standard methods used now.”

    For Sorkin, the future seems unclear.

    “If this leads maple syrup from a semi-wild crop to something farmed, plantation-style, I think that would be tremendously sad,” he says.

    “And that would have implications for multi-generational operations and landscape-scale implications for the working forest in the Northeast. But that’s a huge, huge ‘if.’”

    Joshua E. Brown can be reached at joshua.e.brown@uvm.edu.

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