21 January 2014

Totally rethinking maple syrup

So you think you understand where maple syrup comes from in trees?  Think again...
In October 2013, Drs. Tim Perkins and Abby van Den Berg of the University of Vermont’s Proctor Maple Research Center, revealed the findings of a study at a maple syrup conference in New Brunswick, Canada that sent waves through the industry. In 2010, they were studying vacuum systems in sap collection operations. Based on the observation that one of the mature trees in the study that was missing most of its top was still yielding high volumes of sap, they hypothesized that the maples were possibly drawing moisture from the soil and not the crown. Previously, they had presumed that the sap dripping from tap holes was coming from the upper portion of the tree. But, if the tree was missing most of its crown then, they surmised, it must be drawing moisture from the roots.

In order not to destroy the mature maples in the research forest to test their theory, they went to the maple saplings planted near the lab which are often used to gather data. They lopped off the top of the small trees, put caps on them with a tube inserted, sealed the cap and put them under vacuum. The young trees produced impressive quantities of sap, even without the benefit of a crown...

They realized that their discovery meant sugarmakers could use saplings, densely planted in open fields, to harvest sap. In other words, it is possible that maple syrup could now be produced as a row crop like every other commercial crop in North America.

In a natural forest, which varies in maple density, an average 60 to 100 taps per acre will yield 40 to 50 gallons of syrup. According to the researchers’ calculations, an acre of what is now called “the plantation method” could sustain 5,800 saplings with taps yielding 400 gallons of syrup per acre. If the method is realized, producing maple syrup on a commercial scale may no longer be restricted to those with forest land; it could require just 50 acres of arable land instead of 500 acres of forest. Furthermore, any region with the right climate for growing maples would be able to start up maple “farms”. The natural forest would become redundant...

"Personally the thought of taking maple out of the forest and turning into another row crop saddens me. We have been in the maple business since 2009 and our sugarhouse has a reputation for utilizing the most modern technology available to maximize efficiency of production. Nevertheless, the news of the plantation system has been a lot to chew on since we learned of it. We are relatively new to the trade but have come to love it, one of the principal reasons being our interaction with the thousand acres of forest behind our home. Like Dave Folino, I fear that the industry will no longer be special to New England but will be usurped by entrepreneurs anywhere with the right climate. And on a more visceral level, I feel that maple syrup is and should remain a product of the wild. Aside from mushrooms and game meat, the woods of Vermont hardly yield anything edible. And yet, this exquisite sugar can be extracted from the trees while still leaving them healthy and the forest a home to everything from rare wildflowers to bob cats. For me, knowing its origins elicits an amount of pleasure equal to tasting its unique flavor when I drizzle it over morning pancakes. Finally, I ponder what will happen to the acres of working forests if landowners are no longer making an income from them through tapping the trees. It would be unrealistic to expect all of those landowners to choose conservation."
There's more information at the source article in Modern Farmer and in this article from the University of Vermont.


  1. It would be a pitty to see yet more small farms wither and disapear. My wife spent a few years on a farm as a kid and maple syrup was very important to them.

  2. Is there a difference in the taste or quality of syrup made from mature trees and that of the saplings?

  3. I have always known that sap rises, I presumed it was common knowledge.
    Anybody that has ever grafted a plant knows that sap rises.
    There is even a common saying about rising sap.
    If I had known that nobody else knew that, I could have had my 12 minutes of fame (inflation adjusted).
    Seriously ? People thought that sap flowed downwards ? from the top of the tree ?
    Nobody wondered why trees didn't grow downwards ?
    Don't mean to sound rude, but was this article a joke article ?
    And, obviously a large mature tree will produce far more sap than a sapling, so I believe nothing much will change in the maple farming process.
    You were all kidding me, hey ?

    1. This is the result when people are coming out of the blue and they are doing things as specialists (similar to people from urban areas coming on the country side and giving advices on agriculture and how to grow live stock). I like that: "Nobody wondered why trees didn't grow downwards ?" :)))

  4. As a biology teacher, I would point out that it takes many years just to establish a sapling. The impact of repeated tapping to a sapling would be greater than that of a mature tree. So the longevity of the row crop, even without severing its head (or crown) would not be long. These other factors, beyond the flow of sap under vaccuum, might well make the current system a better choice. So fear not, my purests!

  5. a lot of farmers are using smaller tress these days.

    i think it's not the size of the tree, but the health of it and the soil it grows in. the sugar content of the sap makes a difference in how it boils out.

    right now in vermont we are worried about crown damage because of the weather we've had recently. apparently a sugar maple needs its crown to make sugars that come up in the sap. bad crown damage will decrease yield not in the season immediately following the damage, but in the season AFTER the first summer when it has fewer leaves.

  6. Everyone knows that maple sap goes sideways, not up or down. That's why the taps and tubes work because it's trying to go sideways anyway. And why branches grow out of the sides of trees.
    Sometime hold a bottle of maple syrup upside down. You will see that since the sap prefers to go sideways, none will come out of the bottle.

  7. Um... yea. What WilliamRocket said. How can they not have already known that sap rises? More importantly, don't they know that sap rises due to transpiration & water loss in leaves? Which means that a stump isn't going to have very much flowing sap, flowing for very long. Not to mention the fact that stumps don't grow very well anyway. Leaves are important. I am also wondering whether this was a joke article.

  8. This could actually benefit small farms.
    " an acre of what is now called “the plantation method” could sustain 5,800 saplings with taps yielding 400 gallons of syrup per acre."

    Thinking of the "urban farm" movement... City blocks average around about 2 acres depending on the city. Buy up a block or two of abandoned land in places like Detroit?
    -Or in other areas plant a couple rows of trees between fields as wind breaks to reduce erosion and/or drifting snow?

    1. But understand that to harvest the sap using this method, one needs vacuum-generating apparatus that might not be cheap or suitable for a 1-2 acre lot.

    2. With more trees planted closer together I would think this would be even better suited to a vacuum system than harvesting from more "wild" trees spaced at irregular distances? But yeah, you would have to work out the minimum acreage needed to justify the cost of the vacuum system.

  9. Maple trees use photosynthesis to produce carbohydrates such as sugars. This is used to fuel growth during the growing season and also to store amounts in the root system to fuel the first growth of leaves the next season. It takes fuel to make buds grow into baby leaves. Once conditions are right in the spring, ground water plus stored carbs are made available (rise) to the buds (which are initially tiny and formed in late autumn after leaves fall). Once the buds have enough warm weather and enough lack of sub-freezing nights, the leaves break out of the buds and this results in the roots stopping sending sugars up. The sap turns sour when the buds open. If you take too much sap from a maple, it adversely affects this initial leaf growth, so it might affect the new growth (research will show this). Perhaps they could research sapling size/sap withdrawal/growth rates across many seasons with differing percentages of sap withdrawals to determine optimal draws. There is a market for high-density (slow growth) maple wood where the growth rings are nice and small. The other advantage as far as sap production is that a denser woods converts more of the sunlight falling on an acre of ground via photosynthesis since there is more complete coverage of the ground by shady leaves.

  10. Here's a link to the most well-informed observations on this topic at the Boing Boing comment thread linking to this post -



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