How Maple Syrup Producers Are Protecting Their Product From the Climate

A sweet story of adaptation

By Nikki Kolb

April 21, 2022


A sugar shack in the woods of Vermont. | Photo by capecodphoto/iStock

At Kearsarge Gore Farm, a multi-generational operation tucked into the foothills of Warner, New Hampshire, tapping for maple syrup begins much earlier in the season than it used to, a common theme among producers today.

“Sugar makers used to tap by Town Meeting in early March. Then the schedule changed to be all done tapping by the end of February,” wrote Sam Bower, whose parents started the off-grid farm in the 1980s, in an email between boils in mid-March. “Then it was Valentine’s Day, and this year it seemed like we could’ve caught a run even earlier if we’d been ready.”

The family has been making maple syrup since the beginning, building the harvest into their diversified farm: 500 acres of fields and woodlands, including certified organic maple, organic vegetables, logging, and livestock. They currently have 2,500 taps and sell 600 to 800 gallons of syrup, direct-to-consumer, per year.

This delightful wild crop, come spring, has been harvested across North America for countless generations, making maple both a traditional Indigenous food, and an iconic Northeast product—one that has helped shape the landscape and identity of the region.

In 2021, Vermont, New York, Maine, and New Hampshire were among the top five maple-producing US states, though all saw less output than in the previous year. That’s in line with national production, which has fallen annually since 2020, despite increased international demand over the same period. While Vermont is expected to bring in a full crop (or near to it) this year, early reports suggest that production in states to the south and west of the US maple titan may be less than stellar. And, it’s all because of climate change.

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 Warmer winters, stronger storms, flooding, droughts, soil degradation, invasive species, and an uptick in pests are shortening the maple sugaring season, affecting sap quality and sweetness, as well as overall sugar maple tree health. As a result, scientists predict the optimal syrup production zone will move ever northward into Canada, where Quebec is already the global leader in production, over the coming centuries. (You may have heard the province tapped into its syrup reserves late last year to satiate the world’s growing appetite for this seasonal treat.) But don’t panic—farmers, foresters, and researchers are working to keep maple on the table for years to come.

So, how are Northeast maple producers, and the intersectional communities that have worked with maple trees for generations, adapting to the challenges?

To appreciate that, it’s valuable to understand how sugaring works.

Maple syrup harvesting dates to paleolithic times and was considered a gift from the Creator, explain Paul and Denise Pouliot, Sag8mo and Sag8moskwa, Head Male Speaker and Head Female Speaker of the Cowasuck Band of the Pennacook-Abenaki People. The naturally occurring sweet can only be produced under certain weather conditions, which are responsible for both the sugar content and sap flow.

Maple syrup harvesting dates to paleolithic times and was considered a gift from the Creator.

Sap flow occurs when temperatures dip below freezing at night and thaw during the day—a short window that can appear anywhere from January to April, though most New England producers get their sap in February and March. Sugar content, on the other hand, is dependent on the tree’s nutrient intake over the course of the year. Nutrients are derived from soil and photosynthesis, and stored as carbohydrates. To make syrup, sap is heated until most of the water evaporates, thus transforming raw forest product into a delectable confection. But, warmer temperatures are changing the typical time of collection.

“The season is starting earlier, it’s ending earlier, and the overall duration is compressed, by roughly 10 percent over the last 60 years,” reports Mark Isselhardt, maple specialist at the University of Vermont Extension’s Proctor Maple Research Center, who has worked in the industry for 25 years.

However, a shorter season doesn’t necessarily mean a decrease in production or yield per tree because of the dynamic nature of the sap flow events—if weather aligns, that is. “We generally don’t rely on length of season as a good measure of total yield or total production in any given area,” confirms Isselhardt.

By embracing new technologies like reverse osmosis machines, evaporators, plastic tubing to link trees and ease collection, and vacuum pumps to aid sap flow by artificially lowering pressure within the tubing (sap flows when pressure is greater inside the trees than outside) farmers are producing more syrup than ever before, reducing labor and resources while increasing efficiency and yields. Technology isn’t making the difference alone, Isselhardt clarifies. Altered basic practices, such as simply keeping a closer eye on the weather, play an equally pivotal role.

For generations, the maple sugaring season has been predictable. But reliance on the calendar system (like that well-known adage of tapping on Town Meeting day—when residents in New Hampshire and Vermont gather to vote on municipal issues in early March) can result in missed opportunities that ultimately reduce yields for individual producers.  

“There are also years like last year when we tapped and then waited, and nothing happened,” reflects Bower. “The season didn’t really start, and it didn’t really end because we didn’t have much of a ‘real’ winter that we need for sugaring.”

Despite such year-to-year shifts, Bower says, “So far, climate change doesn’t seem to have had much of an impact on our average production.”

That notion is in line with Isselhardt’s own observations: that production among individual operators is largely dependent on a farmer’s practices, location, scale, and to what extent new techniques are being embraced.

Kearsarge Gore Farm’s resilience, for instance, may be benefiting from tweaks the family has made to their business, such as upgrading their evaporator in 2013, which practically tripled production, and more recently, adding check-valve taps that stop sap from flowing back into trees, along with an improved vacuum system that enables a broader range of tapping across a single tree. These latter innovations help protect the maples, improving overall health and helping the trees to heal from harvesting.

A detailed forest management plan is also critical for maintaining a healthy sugarbush. Some growing standards, like organic certification, even require it. 

First, tree diversity is essential. Isselhardt cautions against whittling groves down to a monocrop—a practice once popular among producers—as culling non-maples leaves the remaining trees susceptible to pests and other invasive species, like the forest tent caterpillar and Asian longhorned beetle.

Thinning is another area where producers should apply restraint. Some thinning is necessary, but too much and multiple rounds in quick succession can shock trees and even lead to root damage, a common threat for sugar maples, which have particularly sensitive root structures that are already reacting to changes in soil composition in some locales. For producers just getting started and those scaling up, Isselhardt recommends designing a tubing system that affords easy future access to avoid excessive thinning, and to facilitate ease of collection as the trees grow.

Structural diversity is important, too. A mix of large, medium, and small trees, trees of varied ages, and those of no economic value, including dead trees, all contribute to forest vitality. Such diverse forests can help store carbon, regenerate soil, and provide suitable habitats for birds and other species that help maintain the overall ecosystem. Growing standards like Audubon Vermont’s Bird Friendly Maple label emphasize and reward these aspects of forest management.

The Pouliots echo these sentiments, noting that Indigenous forest management practices traditionally included maintaining woodland understories and keeping competing species at bay—systems that would have ultimately helped maples.

Indigenous forest management practices traditionally included maintaining woodland understories and keeping competing species at bay—systems that would have ultimately helped maples.

Another way to be adaptive? Branch out. While climate change may have the greatest impact on small farmers (for whom syrup is likely one piece of their business model), diverse farms, like diverse forests, have a greater chance of survival. That makes regeneration yet another important point of emphasis.

“There’s very little planting in maple. It’s almost all natural regeneration. And that’s not easy either,” says Isselhardt. “Sugar makers would be well served to focus on regeneration. In fact, when we survey professional foresters, regeneration is one of the concerns going forward.”

But trees don’t grow overnight, and invasive species like the jumping worm are making soils less hospitable to sugar maple germination. As a result, where we derive syrup may shift from the dominant sugar maple to red maples, which are more adaptable, have a broader range,  greater ability to withstand pests, and thrive in a wider variety of climates. Though more producers are tapping red maples than ever before, Isselhardt addresses the species’ reputation for making inferior syrup. Some researchers, including his colleagues at the Proctor Maple Research Center, are actively working to refute that. What they’ve found so far is that the sap is less sweet but produces more volume and works well when combined with sap from sugar maples.

“The red maples have a lower sugar percentage in their sap, but we're tapping those trees in cold areas of our woods so we're able to get the sap and spread out over our production instead of stressing our current trees,” confirms Bob Bower, who founded the farm with his wife back in the ‘80s, and whose family has started incorporating more red maples into Kearsarge Gore Farm’s production.

While expanding production to include red maples offers a hopeful outlook, the Pouliots have a more sobering view, and question whether the species will inevitably become strained, too. They expressed concerns about the inherent extractive nature of maple sugaring aided by the proliferation of vacuum pumps and cited an Abenaki moral story that doubles as a recipe—not just for making maple syrup, but for living in harmony with nature.

In the story, Gluskabe, a mythical Abenaki figure sent to Earth by the Creator, is dismayed to find villagers neglecting their homes, health, and community to gorge on free-flowing maple syrup. To restore balance and quell overconsumption, Gluskabe limits the supply of the sweet by shortening the sugaring season, watering down the sap, and requiring boiling to produce syrup, all to instill appreciation for the Creator’s gift.

To the Pouliots, the allegory is just as relevant today.

“Unfortunately, commercialism is going to keep on demanding higher volumes,” says Paul Pouliot. “Now everybody’s using vacuum lines, including Indigenous populations that are still doing maple syrup, to keep the production up… but ultimately, you’re shortening the life of the tree by putting it under a stressful condition."

Isselhardt recognizes these concerns, and has co-authored research that found high vacuum technologies did not decrease the growth of healthy maple trees even when used annually for 5 to 10 years, but that following current tapping guidelines—like limiting tapping to one hole per tree, practicing taphole sanitation, and replacing tap spouts yearly—is essential for maple production and sustainability. 

Still, it remains unknown how high vacuum technologies could impact trees if applied annually for 20 years or more, with scientists acknowledging the practice could affect the trees’ carbohydrate reserves and ultimately limit their lifespans. The issue is especially pertinent for stressed and slow-growing sugar maples, which are expected to become more prevalent as climate change progresses.

So, what can individuals do?

For those living in maple belts across the country, buying local is the best way to support their communities, forests, and farmers, and can provide opportunities to learn about producers’ practices. But that’s likely impractical for most maple syrup consumers. For those outside sugaring regions, standards like certified organic and Bird Friendly Maple can help serve as guideposts, but they’re not the be-all, end-all. It’s important to remember that most maple producers are working to sustainably manage their forests, regardless of their certification status, Isselhardt emphasizes. 

While producing maple syrup has its environmental challenges, when it comes to sweeteners, switching from heavily subsidized cane and corn syrup to maple is still one of the most sustainable swaps consumers can make to protect vital forests and encourage carbon drawdown. Doing what we can, individually and globally, to reduce our planetary impact, remains crucial.

“The most effective strategy we have now to deal with climate change is to make decisions on a time scale that isn’t just for this year or the next, but that will have a net positive for future generations decades (or centuries) down the line,” conclude the Bowers, indicating that we must forge ahead with caution. “If there is no collective action around climate change, there may not be a sugaring industry in the future.”

The Pouliots couldn’t agree more.

“People need to stop and think about their ripple,” advises Denise Pouliot. “We’re all a pebble in the pond of life and when we were dropped onto this earth, we all made a ripple, and each one of us is responsible for the ripple that we create. We want to think that we’re all an island, but if you look at the ocean, even islands make ripples. So, people need to stop and think about what they’re doing… Because we’re not here to live life off the environment,” she adds. “We’re here to share the space with everyone else.”

Including the trees.