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It may seem paradoxical, but sugar maple trees need snow to stay warm and grow.
Every winter, a deep blanket of snow – 8 inches deep or more – covers about 65 percent of the northeastern sugarcane trees. Without this insulating snow, the soil freezes deeper and damages the shallow roots of the trees.
A recent week in study [GlobalChangeBiology warns that maple trees will grow 40 percent slower without the snow cover. With climate change reducing the amount of powder snow in New England, the study says that this poses problems for the trees – and for humans – as the trees not only syrup but also absorb some of the carbon pollution.
"As temperatures continue to rise and snowpacks continue to decline, this indicates that our maple forests are not growing so much and therefore do not deposit as much carbon," says Pamela Templer, biology professor at Boston University and senior author the study.
Templer says that while forests in the US extract carbon dioxide from the air and store it in trees, plants and soil, they could offset somewhere between 5 and 30 percent of American carbon dioxide emissions.
Maple Tree Growth Damage It also has more immediate economic consequences.
"Many people in the northeastern United States rely on sugarcorns," says Templer. "And if these forests do not grow so much, it will probably affect the livelihoods of those who rely on this tree species."
"This work is a big deal," says Peter Groffman, biogeochemist at the Cary Institute for Ecosystem Studies in New York, who has collaborated with Templer in the past, but was not involved in the current study. "When you talk to people about forests in New England, the # 1 question people ask is," What will happen to the sugar maples? "This is very important for this question."
While scientists have known for years that frozen soil damages the roots of sugar-maple skulls, Groffman says it was unclear whether this damage affected tree growth.
"That's the exciting thing about this study," says Groffman. "It shows – with very meticulous and very careful methods – that the manipulation of snow to freeze the soil in the long term reduces the growth of the tree."
The researchers also found that the amount of northeastern forests with snow cover could shrink by 95 percent by the end of the century – from 33,000 square miles to only 2,000 in the worst case scenario. From an area that is larger than Maine, it is less and less, Connecticut is only half as large. Even with a lower emission scenario, the area covered by the snow cover could still drop 49 percent to 16,500 square miles, says study author Andrew Reinmann, forest ecologist at City University of New York.
"If you like skiing, go ahead," he says.
The research that led to the maple study began a decade ago. During five winters from 2008 to 2012, Templer and her team shoveled the first four weeks of winter snowfall in the 8,000-acre Hubbard Brook Experimental Forest, New Hampshire. This corresponded to the diminished snowfall of New England expected at the end of the century. (They left the first few inches of snow in place so they could not accidentally scoop up dirt later.) After four weeks of eviction, they naturally accumulated the rest of the winter.
After five shoveling weeks and then a year off to see if the trees would bounce back, the researchers took core samples of the sugar maples and examined their growth rings. The growth of sugar guards slowed by about 40 percent after the first two years of the experiment. They did not recover in the past year.
Reinmann says it is unclear whether the trees will return to normal after a few years of normal snow, or whether the damage is permanent.
"Whether this is or does not mean that sugar maple is dying or simply losing a competitive edge is not very clear," he says.
The researchers find that warmer winters can have some benefits, such as lower heating costs and longer growing seasons. Furthermore, according to Templer, maple sugar production has been able to keep pace with climate change so far.
"You can still extract juice and make delicious maple syrup," says Templer. "The concern is that we will not have maple syrup in the long run just because the conditions needed to make [it] disappear."
This story comes from us member station WBUR in Boston.