Vermont, New York and Maine are the top producing states, and produce about 80% of the maple syrup in the nation, with Vermont the overwhelming top producing state. In 2021, the three states produced more than 4 million gallons of maple syrup in 2021 valued at more than $100 million, according to USDA’s National Agricultural Statistics Service.
USDA’s National Institute of Food and Agriculture funds research and Extension projects in key maple-producing states through numerous grant programs, including Hatch, McIntire-Stennis and Smith-Lever capacity funding as well as the Agriculture and Food Research Initiative (AFRI), the nation’s leading and largest competitive grants program for agricultural sciences. These grants are available to eligible colleges, universities, and other research organizations.
Jason Lilley, assistant Extension professor of sustainable agriculture and maple industry educator with University of Maine (UMaine) Cooperative Extension, said climate change is to blame for the early start of maple sugaring season. “If we were experiencing this in a single season, I would say that it's just a result of an abnormally warm winter. However, this has been a widely recognized trend among the maple industry over several seasons.”
“In the Northeast, late winter and spring are the times of year that are experiencing the most dramatic climate change, so it’s perhaps no surprise that tapping patterns are changing,” said researcher Heidi Asbjornsen, professor of natural resources and the environment at the University of New Hampshire (UNH).
Mark Isselhardt, a maple specialist with the University of Vermont (UVM) Cooperative Extension, said 2023 has certainly been an odd year for weather with lots of warm weather in December, January and February in the lead up to the sugaring season. “January was the warmest on record in many places. And yet, we won’t know the impact of all of it until the season wraps up -- whenever that happens.”
Extreme Fluctuations in Weather
Maple sap runs when there are freeze-thaw cycles, Asbjornsen explained. The best tapping window is the 6 to 8-week period where the number and magnitude of freeze-thaw cycles are the greatest. If this window occurs earlier in the winter-dormant period, maple sugar producers will tap trees earlier.
“This winter we’ve experienced particularly extreme fluctuations in weather with temperature differences of 30 to 40 degrees Fahrenheit from one day to the next not uncommon, which has likely caused earlier freeze-thaw events,” she said.
In a typical year, the region might have one or two days in mid- or late January when temperatures are over 40 degrees Fahrenheit, Lilley said. In those scenarios, Extension staff encourage producers to wait as tapping too early for a small amount of sap can be detrimental to late season (often heavier) sap flow due to contamination and plugging of the tap holes.
“However, this season there were long-term forecasts with ideal sap flow conditions, so many producers got started in the first week of February,” he said.
Maple Syrup Production on the Rise
The fact that sap is flowing earlier in the season should not have a negative impact on the industry, Lilley said, as long as the region doesn’t experience a very quick and abrupt spring warm up, which would shorten the back end of the season.
“Overall, technology has kept pace with this issue. For example, it’s now possible to obtain higher yields per tap due to vacuum systems and more efficient boiling techniques, which has allowed maple syrup operations to stay profitable,” Asbjornsen said.
Isselhardt agreed that syrup production is trending positive both in terms of total production due to expansion in the number of taps and in yield of gallons per tap. The later can be partially explained by the increase in adopting modern techniques including pumps capable of high vacuum and continuous service, improved sanitation practices, better understanding of how tapping practices impact yields and better materials.
“Whereas an operation of 2,000 to 3,000 taps would be considered good size in the past, we now see producers starting off with 10,000 to 20,000 taps. Given that labor to help with tapping is limited, it makes sense that we hear reports of people beginning to tap as early as January or in some cases December,” he said.
Sugar Maples Under Other Climate-Related Stress
However, NIFA-supported researchers and Extension staff are seeing other climate trends that could hamper maple syrup production including long periods of higher-than-average temperatures; more frequent extended droughts followed by extreme downpours; severe weather; high wind events; and soil saturation.
“These extreme conditions stress the trees during the growing season, when the trees are producing sugar through photosynthesis. A single stressor event can easily be withstood by the trees, as they have evolved with these events. But having multiple stressors per year over several years leads to a concern about groups of trees' long-term viability,” Lilley said.
Another issue that may, over time, affect the health of sugar maple trees is the change in snowpack in the Northeast. When the ground is not protected by a deep snowpack due to warmer winter temperatures and/or changing precipitation patterns, this would allow for deeper frosts, Asbjornsen said.
“Deeper frosts can damage fine roots and reduce trees’ ability to move water from the soil into the roots. However, more research is needed to better understand the impacts of changing snowpack on the maple industry,” she said.
In addition to damaging sugar maple roots, Isselhardt said a reduced snowpack will have a negative effect on the next generation of sugar maples as it is the tree with perhaps the coldest germination temperature. Lack of snow also reduces moisture available to trees during spring.
And while not widespread, UMaine Extension staff also are receiving reports of sugarbush decline from producers. This includes producers reporting concerned about a few trees to one case of full sugarbush decline from one small producer. Sugarbush refers to a forest stand of maple trees.
“Maple trees are complex organisms. They have back-up systems to allow them to withstand poor years. With that in mind, there is not a good correlation between, for example, a drought in one season, and sap yields or sugar content the next. There are research projects being launched to investigate this connection between weather conditions and sap quality,” Lilley said.
Invasive plants and animals also are impacting the region’s forests. Isselhardt said some areas are seeing invasive plants establish themselves and create low shade, preventing maple seedling from establishing. Invasive earthworms that transform the forest floor by consuming the organic humus layer of partially decomposed leaves also are negatively impacting the maple’s ability to become established.
Asbjornsen said forest tent caterpillars are another stressor affecting sugar maple health. When outbreaks occur, this causes defoliation reducing trees’ ability to maintain photosynthesis and growth. If multiple outbreaks occur over consecutive years, this can have a detrimental effect on tree health.
Producers Also Are Stressed Out
And it’s not just the maple trees that are under more stress due to the climate change-related impacts. With a less predictable start of the season, producers also are under more stress to make decisions on when to get started.
“Large producers need to start tapping several weeks in advance of the first run to get everything done. They cannot use the forecast to determine when to get started. Smaller scale producers often need to arrange time off from other jobs, which can be hard to manage with an unpredictable season launch date,” Lilley said.
Producers who tap trees based on a “traditional” date will sometimes miss out on early sap flow events given the trends in earlier warming, Isselhardt said. This can lead to lower yields in years when the season ends early.
There is also risk associated with abnormal, high temperature events such as what was seen in 2012. “In 2012, we saw four to five days with temperatures in the 70s in March. This resulted in tap holes shutting down because of microbial growth in the tap hole and the trees natural wound response system. Warm temperatures also impact the sap quality because microbial growth in collection tanks t can lead to low quality and off-flavored product,” he said.
Old tapholes and tapholes that shut down are an especially relevant problem for small producers relying on gravity to collect sap, Asbjornsen said.
In addition, sap quality can be affected by early bud swell of the trees. Under these conditions, the sugar structures and flavonoids in the sap change and produce off-flavored poor quality syrup, Lilley said. Mid-season warmups are often temporary, but with more warm mid-season days, sap quality is likely to decrease.
Working on Solutions for Maple Sugar Producers
As a result, NIFA-funded maple researchers and Extension specialists are working on all aspects of these issues. There are project plans in the works to track weather date and sap quality.
“In Maine, we are collaborating with the Maine Forest Service, and maple producers to identify areas of tree decline, and to diagnose potential causes. We are also collaborating to educate and provide resources for maple business managers, and woodland owners on sustainable sugarbush management strategies to optimize the health of the woods, therefore doing as much as we can to decrease the stress on the trees,” Lilley said.
In New Hampshire, Asbjornsen’s NIFA-funded project, which includes collaborators Steve Roberge with UNH Cooperative Extension, Matt Vadeboncoeur with UNH’s Earth Systems Research Center, and doctoral student David Moore, is investigating the potential to harvest sap and produce syrup from seven different non-maple species.
“By diversifying the syrup industry, this may allow producers to utilize other species that are better adapted to climate change, or to modify their sap collection and syrup production efforts depending on the weather patterns each year and which species are producing more sap,” she said. “We anticipate having results from this research ready to share with producers within the next two years.”
At the University of Vermont, the Extension Maple Program is engaged with sharing the latest information and best practices in three broad topic areas: sugarbush health, sustainable high yields of sap/syrup and syrup quality. For example, UVM developed 13-video series on “Sugarbush Management.”
Extension staff also present the latest information on topics related to climate change and maple syrup at conferences and industry group meetings, respond directly to producer inquiries, write articles in maple industry trade publications, serves on industry committees, and help draft climate policy statements, such as for the Vermont Maple Sugar Makers Association.
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