Indiana Dunes research looks at climate impact on syrup

PORTER, Ind. (AP) - A tall, stack of pancakes wouldn't be complete without a side of maple syrup, but rising temperatures due to climate change could affect where the sweet, amber liquid is produced and its availability.

Scientists and citizen volunteers will be researching how the sugar maple is affected by climate change at Indiana Dunes National Lakeshore for the next few months as maple sap starts to flow, the Post-Tribune reported (http://trib.in/24dkjuO ).

Joshua Rapp, a Bullard Fellow at Harvard Forest in Massachusetts, and other researchers have been collecting data for the past five years on the quality of maple sap in New England and the mid-Atlantic states.

"We've been measuring the amount of sap, its sugar content and the secondary chemicals in sap that give it its distinctive taste," Rapp said. "We're interested in how all those things are influenced by climate from south to north."

Rapp was interested in getting data collected from a broader range of climate conditions, so he secured a grant from the New England Climate Science Center and found that the research was a good fit for the Dunes, which has run its Maple Sugar Time educational program at Chellberg Farm for 39 years.

The park usually taps around 60 trees for demonstration purposes, which can yield more than 20 gallons of syrup.

Wendy Smith, education coordinator at the park's Great Lakes Research and Education Center, said 33 volunteers have signed up to collect samples of sugar maple sap on particular days of the week, with 14 people as backups. If trees have collected at least a liter of sap, teams of four or five people will weigh the bag, take a small sample and measure the sugar content.

Smith said it's tricky getting the sap to run sometimes. Basically, the nighttime temperature must be 25 degrees or lower followed by a daytime temperature of 40 degrees or higher. One sample has been taken so far this season, but she said it's still pretty early.

Larry Yoder, a retired biology professor at Goshen College, said it makes sense for the research to expand to the Midwest.

"Though Vermonters would have you believe that maple syrup originated there, sugar maples are actually native to the Great Lakes region, and you can find them down into Kentucky and Tennessee," he said.

Yoder said the length of the season has less to do with maple sap collection than the number of days where the freezing and thawing occur. Yoder's family runs a farm in Huntertown, Indiana, that has produced maple syrup for five generations.

"I suppose everyone was ready for spring in the last few weeks, but I am thrilled getting a good hard freeze," Yoder said. "As we come out of winter, the days get longer, temperatures moderate, and we get into the freeze-thaw-freeze cycle, tapping should happen around the end of February into March in northern Indiana. Those in Quebec are still in the in middle of winter, so theirs will be in late March into April. In southern Indiana, they were able to tap at the end of January."

Yoder said farmers are curious to the effect climate change will have on their agricultural operation.

"Yes, sugar makers are watching carefully," Yoder said. "Over the long haul, you may see weather patterns shifting for the next decade or so. You may see that the season starts earlier. But it fluctuates." Yoder said. "What happens as we see climate shift? Well, one possibility is the whole freeze-thaw pattern shifts north. Will we have in southern Indiana the climate conditions that you see a state or two south of us?"

Joy Marburger, an adjunct professor at Purdue University North Central in Westville, said the sugar maple won't tolerate really warm temperatures.

"You can see the trend line on maple syrup production with the U.S. versus Canada," Marburger said. "The U.S. used to have more production than Canada. Now, Canada is the leading producer."

Marburger, who was the research coordinator for the Great Lakes Research and Education Center, said climate change won't have as profound effects on water levels for the Great Lakes as it will on the Atlantic and Pacific Coasts.

"But there will be temperature effects as carbon dioxide is a major insulator of heat," Marburger said. "There will also be increased variability of weather patterns, drought and heavy rainfall."

A colder winter means the season starts later, as Rapp's data shows that southern sites have more sap in those years. But in a warmer winter, the season starts and ends early and production is lower than expected.

Rapp said that the sugar content can vary from about 1 percent to 5 percent and that can impact how much syrup a producer can make. If the sugar content is on the low end, a producer will need more sap to make syrup.

"It can have a huge effect on the amount of syrup a producer can make," Rapp said.

Yoder said the amount of sap is dependent on a couple of other factors.

"If there is a dry summer and fall, a season where rainfall is below average, it can affect the moisture available for the sugar maple tree roots and that's one factor that may change the amount of sap," Yoder said. "A much more significant factor is how long do we have that period or window of freezing and thawing."

Beyond changing temperatures, sugar maples face threats from acid rain and the Asian longhorn beetle.

Rapp said acid rain leeched calcium from the soil, which sugar maples are very dependent upon. Since the 1980s, the United States has been working to reduce emissions in sulfur dioxide and nitrogen oxides from vehicles and power plants. These efforts have had positive results, but Rapp said the sugar maple hasn't bounced back immediately.

"The reduction in acid rain that should have positive effect hasn't yet, because there is a lag. Once you take the calcium out of the soil, you have to wait for it come back. Other areas have more calcium in soil, like limestone bedrock. Indiana has a lot of limestone bedrock, so it may rebound faster."

Yoder said the frequency of international travel and shipping has introduced the Asian longhorn beetle to the United States, where it has attacked maples in Chicago area forest preserves and in the Cincinnati area.

"It's similar to the emerald ash borer and the ash trees," Yoder said. "They like to lay eggs and larvae bore into the maples. But the only fix it to chop down every maple tree. The U.S. Forest Service has been watching this very closely because we would not want that thing to get loose."

Yoder said these are the impacts of seven billion people living on the same planet.

"It's just the way life is going to be," Yoder said. "But I am optimistic about future of the sugar maple for several reasons. We have plenty of maple trees and Indiana has maybe in the single digits percent of them tapped. So there are plenty of trees and there's more interest with whole change in culture toward making local foods, natural products, and the interest in spiritually and physically reconnecting with nature."

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Information from: Post-Tribune, http://posttrib.chicagotribune.com/