For years, the chirping of the spring peeper frogs was one of Valerie Lowry’s signals that the maple sugar season was coming to an end. Twice the frogs would emerge, filling the Highland County air with their familiar call, and twice they would quiet. On their third appearance, Lowry knew, the sap would stop running, and “you quit making syrup.”

But this past winter, that long-running pattern changed.

“This year, we heard the peep-frogs barely one time, and then the trees shut off,” she said. “It’s just a very different sequence.”

Lowry, who with her husband Pat runs Back Creek Farms in Monterey, the county seat of Highland, is one of many maple syrup producers in Virginia seeing once-regular seasonal patterns become uneven or change entirely. Snow is no longer reliably present during tapping. Sudden warm days are more common, disrupting sap flow. And, most critically, the tapping season itself is slowly creeping backwards, from March a generation or so ago to January.

“Even 50 years ago to now, we’ve already back-pedaled two months,” said Missy Moyers-Jarrells of Laurel Fork Sapsuckers.

According to a study in Forest Ecology and Management released last month by a team of researchers from institutions including Harvard, Dartmouth and the University of Virginia at Wise, those observations may be not merely anecdotal but yet another ripple effect of climate change.

“Climate change will have profound effects on syrup yield across most of [the] sugar maple’s range,” the authors concluded, while also spurring “drastic shifts in the timing of the tapping season” and “declines in syrup yield and higher frequencies of poor syrup production years across most of the U.S. range.”

Most hard-hit will be those places at the southern end of the sugar maple’s range, including Virginia and Indiana. These sites, the researchers found, will likely “produce almost no syrup by the end of the century.”

The natural distribution map for Acer saccharum, better known as the sugar maple. (U.S. Geological Survey via Wikipedia)

For Virginia’s maple syrup producers, those dire predictions could spell an end to an industry that in recent years has been striving to expand. Remote Highland County, which shoulders up to the West Virginia border and every spring is flooded with tens of thousands of visitors to its annual Maple Festival, has been touted in the region as an example for other jurisdictions looking for new economic opportunities.

“Only about 2 percent of the maple trees in Highland are actually tapped,” a Roanoke Times editorial noted in 2018. “Highland could produce a whole lot more syrup. So could other Virginia localities, especially those in the mountains.”

Others are also banking on the industry’s potential. Efforts are underway to create an association of maple syrup producers in the commonwealth, while West Virginia, drawing on more than $200,000 in grant funds from the U.S. Department of Agriculture’s Acer Access and Development Program (“Acer” is the Latin name for the maple genus), is seeking to bolster the maple industry in central Appalachia through research and education — including a multi-year study examining correlations between temperatures and sap flows that has planted probes and a weather station on Laurel Fork Sapsuckers’ land.

But even with so much activity afoot, Moyers-Jarrells said that Highland producers aren’t immune to climate change worries.

“I definitely recognize climate change for sure, and I’m aware of that. I can see it in my sugar production,” she said. But at the moment, she added, “maybe I’m not looking further than 10 years out.”

Some losses have already occurred, although it isn’t clear whether they are related to climate change or individual economics. Numbers from the U.S. Census of Agriculture show maple syrup production dropping across the board in Virginia, from 1,800 gallons of syrup and $78,000 in production value in 2012 to 1,385 gallons and $66,000 in value in 2017.

Not everyone is seeing declines, however. Lowry said that Back Creek Farms hadn’t seen its production go down and cautioned against alarmism.

“For years, things were very regular — you kind of knew what to expect during the season,” she said. “The last few years, I certainly can’t say it’s been worse. Some years are better, some years aren’t so good, but it’s just very unpredictable.”

Besides, she added, “It’s hard to take a 2100 perspective on something you see from year to year.”