Maple syrup season may begin one month earlier, while the sap sugar content will decrease by 0.7°Brix
How do you like your pancakes? With some maple syrup? Alas! The experience may not be the same for your granddaughter. For, maple trees may start losing their sweetness by the end of the century. Blame global warming.
Traditionally, the sugaring season starts between February and April of each year — sap from sugar maple trees are extracted and converted into syrup. But climate change is set to shift the timing of that cycle, impacting the syrup production, according to researchers from Dartmouth College, in the United States.
When sugar maple tree begins thawing during the early spring, the sap starts moving through the tree to the tap.
By 2100, this process may begin one month earlier than it did between 1950 and 2017, according to the study published in the journal Forest Ecology and Management. The sugar content in saps will decrease by 0.7°Brix, it showed. Brix is the sugar content of an aqueous solution
Maple syrup production is dependent on two climate-sensitive factors: Sugar content and sap flow.
While sugar content is determined by carbohydrate stores influenced by previous year's growing season conditions, sap flow depends on the freeze-thaw cycle, Lutz explained.
To understand, the team measured the volume and weight of the sap samples from 15 to 25 mature sugar maple trees. The saps were analysed daily during the tapping season — from January to May — for six years.
The researchers also took daily temperature readings and also at the annual variability of the sap flow from tree to tree and from year to year.
They found that “the timing of sap collection advanced by 4.3 days for every 1 degree Celsius increase in March mean temperature. Volume of sap peaked between January-May mean temperature of 1°C, and sap sugar content declined by 0.1°Brix for every 1°C increase in previous May-October mean temperature”.
In some locations, “as the climate gets warmer, the sugar maple tapping season will shrink and get closer to a December date,” said co-author David Lutz, a research assistant professor of environmental studies at Dartmouth.
The syrup yield across most of sugar maple’s range will be significantly affected by climate change — syrup yield per tap will moderately increase in Canada, but US will likely have poor syrup production years.
To deal with a shortening season, some producers have taken pro-active measures like using “vacuum-related tapping methods to ensure that sap collection remains steadfast when conditions are conducive to sap flow,” Lutz noted.
Some are also adjusting the structure of the tree stands to handle unpredictability, the researchers noted.
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