Study: Maple syrup production declines after big seed year

November 03, 2014

For decades, maple syrup producers have eyed the weather to help understand spring sugar yields. But new research in the journal Forest Ecology and Management reveals a more valuable metric for understanding - and even predicting - syrup production: how many seed helicopters rained down from the trees the year before?

"Weather affects how much sap will flow out of the tree, but sap volume is only one piece of the puzzle," says Josh Rapp, who as a postdoctoral fellow with Elizabeth Crone, associate professor of biology at Tufts University and senior author on the paper, analyzed the factors influencing 17 years of maple syrup production at 28 sites in Vermont.

What really matters to maple syrup producers, Rapp explains, is the amount of sugar in the sap: "Sugar maple sap is 2 to 3 percent sugar. The rest is just water to boil off. Sweeter sap is more profitable. If you start with sap that's 3 percent sugar, it takes a third less sap to make a gallon of syrup."

So, what predicts how much sugar is in the sap? "Not weather," says Rapp. "Weather alone was a surprisingly bad predictor of how much sugar came out of the taps over those 17 years," says Rapp. "That tells us there is something else at play."

For several years, Rapp and Crone have been studying "mast" seeding events--years when trees collectively produce far more seeds than usual--at the Harvard Forest in Massachusetts. In sugar maples, mast seeding tends to occur every 2 to 5 years.

Recent mast seeding events occurred in Vermont in 2000, 2006, and 2011. Rapp's research shows that in Vermont, syrup production declined following every mast seed year.

"Both seeds and sugar are made from carbohydrates stored in trees," explains Crone. "When a tree produces a lot of seeds one summer, then the next spring, the carbohydrate bank account is low for making sugar. It's a matter of budgeting resources."

Looking ahead to next year's harvest, Rapp notes: "At the Harvard Forest, and likely throughout the northeast, the seed crop was small this year, suggesting the 2015 maple syrup harvest should be a good one."

Rapp explains weather's role in these predictions: "The best way to predict syrup production is actually a combination of factors: proportion of trees with seeds, minimum and maximum March temperatures, and maximum April temperature. Those factors together explained 79% of the variation in syrup production in Vermont from 1998 to 2014."

Because seeds develop a full six months before syrup harvest, Rapp hopes this study can help syrup producers plan ahead. "Maple syrup is a complicated natural resource," he says. "Hopefully this research can give producers a window into the upcoming season."

"The idea of looking at the costs of seed production came from very abstract models developed by mathematicians in Japan," adds Crone. "One of the purposes of academic science is to come up with general insights that help us see applied problems in new ways. This is a good example of that kind of insight."
-end-
The Harvard Forest, founded in 1907 and located in Petersham, Mass., is Harvard University's outdoor laboratory and classroom for ecology and conservation, and a Long-Term Ecological Research (LTER) site funded by the National Science Foundation. Its 3,700 acre property is one of the oldest and most intensively studied research forests in the U.S. Open to the public year-round, the site includes educational and research facilities, a museum, and recreational trails. More information can be found at http://harvardforest.fas.harvard.edu/.

Photos and the complete scientific paper are available at http://harvardforest.fas.harvard.edu/press-resources-sugar-maple-masting-story-113.

For an interview with one or more of the scientists, contact Clarisse Hart, Harvard Forest Outreach Manager.

Citation: JRapp and ECrone. 2014. Maple syrup production declines following masting. Forest Ecology and Management 335(1): 249-254. Available online 27 October 2014. DOI 10.1016/j.foreco.2014.09.041.

Harvard University

Related Maple Syrup Articles from Brightsurf:

China's most important trees are hiding in plain sight
A research collaboration between Chinese and American scientists has synthesized long-term biodiversity data from 12 immense forest study plots spanning 1,500 miles, from China's far north to its southern tropics.

Fructose and glucose in high fructose corn syrup deliver a one-two punch to health
Consuming high fructose corn syrup appears to be as bad for your health as consuming sugar in the form of fructose alone, according to a new study from researchers at the University of California, Davis.

Global warming is changing our plant communities
In a comprehensive study of nearly 20,000 species, University of Miami research shows that plant communities are shifting to include more heat-loving species as a result of climate change.

Sweet coolers a gateway to increased alcohol consumption
Sweetened alcoholic beverages can promote harmful alcohol consumption among teens, new University of Guelph research finds.

An artificial 'tongue' of gold to taste maple syrup
A chemistry professor at Université de Montréal has developed a new test using gold nanoparticles to establish the flavour profile of maple syrup and help producers evaluate its quality.

30-year study identifies need of disease-modifying therapies for maple syrup urine disease
A new study analyzes 30 years of patient data and details the clinical course of 184 individuals with genetically diverse forms of Maple Syrup Urine Disease (MSUD), which is among the most volatile and dangerous inherited metabolic disorders.

Climate change unlikely to drive sugar maples north
Sugar maples won't be heading north anytime soon, despite climate change, according to a new study published in the Journal of Ecology.

Climate change study finds that maple syrup season may come earlier
Once winter nights dip below freezing and the days warm up above freezing sap begins to flow in sugar maples marking the start of the syrup season.

Striped maple trees often change sexes, with females more likely to die
Although pollen has covered cars for weeks and allergy sufferers have been sneezing, we think of sex as being the realm of animals.

Aftershocks of 1959 earthquake rocked Yellowstone in 2017-18
A swarm of more than 3,000 small earthquakes in the Maple Creek area (in Yellowstone National Park but outside of the Yellowstone volcano caldera) between June 2017 and March 2018 are, at least in part, aftershocks of the 1959 quake.

Read More: Maple Syrup News and Maple Syrup Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.