Climate change could threaten breakfast. According to a new study, sugar maples that provide sap for syrup may not survive the hot and dry climate caused by global warming.
Sugar maples in the northern hardwood forests across eastern North America are particularly drought-sensitive. As global temperatures rise, the lack of enough water could stunt their growth, a new, decades-long study found. The number of sugar maple trees will decrease, diminishing the amount of maple syrup available and eliminating the stunning colors of these forests during autumn.
"This is probably the most striking species in these forests," Inés Ibáñez, forest ecology professor at the University of Michigan, told Newsweek. "When people go to see the foliage, they pretty much go to see the sugar maples because they are the ones that have these incredible colors—almost like the forest is in flames."
Ibáñez was the lead author of the study, which was published in Ecology on Wednesday. She and her colleagues analyzed nearly 20 years' worth of data from four forest sites in Michigan, totaling 1,016 trees between 1994 and 2013.
The researchers were specifically hunting down the effects of two factors. They wanted to know how a warmer and drier climate would affect the trees and how excess nitrogen from human activities could curb the negative effects from a warming climate.
The data came from a study that began in 1987 to find out how climate and atmospheric deposition affect forest growth and the ecosystem in the Great Lakes region. Back in 1994, they began adding excess nutrients to simulate what is expected in natural forests by the end of the century. In real life, such excess nutrients often result from human activities such as cars, power plants, factories, and fertilizer used in agriculture. These excess nutrients often result in negative effects for certain ecosystems.
In Michigan, the alkalinity of the soils in that region protects them from the negative effects of excess nitrogen. Researchers were hoping the excess nutrients would offset the negative effects of a warmer and drier climate in the future.
But the results proved worrisome for the famous trees. According to the scenarios the researchers used, if the climate remains the same as it is now, tree growth would not be adversely affected, the study found. But if the changes are more extreme, Ibáñez said, "then growth rates are going to go down quite a bit for this species." The extra nutrients from, oddly enough, pollution won't be enough to curb those effects. Climate change will increase the demand for water, and as less water is available, the tree growth will decrease. And those kind of extreme changes are exactly what may come to pass.
As a brief in Science magazine pointed out, enjoy your pancake syrup while you still can. The researchers ran two different future climate scenarios. In a world that's one degree Celsius warmer, the growth rate of trees will drop. At 5 degrees Celsius warmer with 40 percent less rain, tree growth will drop and the species will also eventually disappear—particularly in the lower peninsula. Ibáñez said other species, such as the oak tree, would take over as sugar maples die off.
The abstract concept of climate change becomes a lot more personal when you think of how it might affect the color of autumn leaves or pancake syrup. But the northern forests of the world have another crucial benefit to keeping global warming from worsening even more. The forests soak up the greenhouse gas carbon dioxide, removing about one-quarter of the gas that is emitted from fossil fuel burning each year, according to the researchers.
Understanding how forests react to a changing climate helps illuminate how, or even whether, future forests will soak up carbon dioxide from the atmosphere. "That, in turn, will have a feedback effect on global temperatures," Donald Zak, the study's co-author and ecology professor at the university, said in a statement.
This study was unique in that it was able to glean valuable information from two decades of data. "Some questions cannot be answered with just one year of experimentation," Ibáñez said. "They need several years or even decades to be able to be answered."
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