Syrup skips a beat: as the world warms, our southernmost sugar maples are feeling the effects, and that's especially troubling for one Virginia town.

Every year since 1958, over two weekends in late March, Monterey, Virginia, swells with tourists, booths, and banners. On a sunny, cool Saturday in spring, a line of cars streams down out of the mountains, drivers craning their necks for a glimpse of the tree that brings them to this remote town in the first place.

The sugar maple.

It's a tree that gives shade in summer, dazzling color in fall, and maple syrup--along with a well-loved festival--in the spring.

From Quebec to this southernmost U.S. syrup-producing region, scientists say the sugar maple is now in decline and, with it, an entire industry and its traditions.

While oak and hickory make up most of Virginia's forests, Highland County, with its 4,000-foot elevation, is prime maple country. A stone's throw from the West Virginia border, its climate and terrain have earned it the name "Virginia's Switzerland." Crooked signs mark its sugar camps, pointing down country roads that vanish into folds scattered with sheep and spruce. For more than 200 years its inhabitants have cultivated the sweet sap, barely noticing the creep of global warming that has left them tapping trees in T-shirts in the once bitter-cold month of January.

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This year, some of the old-timers missed the season altogether, while others took the cues, left their coats, and started tapping trees earlier than ever.

"They ran like crazy when we first opened," Ivan Puffenbarger tells a couple waiting in line to buy syrup at Puffenbarger's Orchard. The rustic, low-slung sugar shack pipes steam through the roof as a bevy of machines toil away. Entering the tilting shed, tourists encounter a strange scene, midway between a chemistry lab and the days of the horse-drawn plow.

Seated near a steaming vat, surrounded by milk cans and maple jugs, the 69-year-old Puffenbarger fields questions. One by one, curious tourists inquire about every aspect of sugaring.

A typical run lasts six straight weeks, Puffenbarger says, with perfect sugar weather being "20-50." That is, nighttime temperatures of around 20 degrees, with daytime highs near 50. This year, one glitch after another played havoc with those hoped-for conditions, leaving Puffenbarger and his wife, "Sis," scrambling to stay on schedule.

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Stop and peruse the Highland County Museum, which many tourists visit before driving out to the sugar camps, and you can see just how the season has shifted. A leaflet on sugaring from the museum's maple exhibit begins, "Late February ... when the days are sunny and the nights are still cold, is the time to watch the sugar maples."

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According to Janet Mullenax, who works in the museum, the producers who didn't start their taps until February this year were just following time-honored tradition. But those who had a successful season say that by the first week of February, they'd had three good runs already. Now, in March--the usual peak of the season--a cold spell has halted the flow of sap as surely as a faucet being closed.

"It's a-happening," Ivan Puffenbarger says of climate change, "but the amount you make hasn't decreased that much."

Surrounded by jugs of syrup, clouds of steam rolling off a vat, and the curious throngs of visitors who inspect yellowed news clippings that paper the walls from festivals past, it's hard to imagine that much has changed since shiny machines replaced bucket and wooden spile. Or that a hundred years from now, it could all be gone.

A VANISHING SOUTHERN TRADITION

"I had no idea they make syrup in Virginia on this scale!" a woman exclaims as she edges towards the treats counter inside Puffenbarger's sugar shack.

Over the two weekend-long festival, Highland County, with its population of 2,500, draws tens of thousand of visitors. Given the region's almost invisible tax base, the spring festivities amount to a cash cow for the farm-based economy and its producers. The Puffenbargers receive about a third of their annual income from syrup, and take in "90 percent of our syrup income in four days." Jay Eagle, another large producer, says syrup accounts for half of his livelihood.

For most of the year, sugar farmers here scrape together a living farming beef cattle and sheep, practicing carpentry or other trades. But maple syrup is rarely off their minds--or their tables.

There's equipment to be maintained and, for some, syrup sales, including shipments abroad, continue through the year. "June and July are the deadest months," Eagle says. That's when he trades his state-of-the-art evaporator and sap-collecting tubes for house painting tools. Puffenbarger farms cattle and sells the newest syrup equipment.

All in all, "it's risky," Eagle says of the syrup trade. "We've got no new producers. Basically, everybody's getting lazy. It's not 8:00 to 4:00." Both Eagle and Puffenbarger are the fourth generation of their families to tap trees, but almost everyone here has a maple story to tell; a single tree or a whole stand on tap.

While Highland County's blustery Appalachian peaks nourish a productive swath of sugar maples, Virginia's syrup trade is nowhere near competitive with the Northeast.

According to Leslie Colburn of the USDA/NASS, Virginia's annual syrup yield isn't even counted. Nor does the state have a grower's association or a chapter of the North American Maple Syrup Council. Maple syrup was last picked up in the 2002 Census of Agriculture, which indicates that the number of farms tapping maple trees increased from 5 in 1997 to 26 farms in 2002. The next census won't be conducted until 2007, Colburn says. Until then, there will be no statistical evidence of any decline in the syrup industry here.

The nation's southernmost growers will tell you, though, that syrup season is skipping beats at both ends. "We had a four week season this year," Jay Eagle says. "We used to go into early April back in 1980. It's been a gradual change. Some call it global. Whatever it is, it's changed."

PEOPLE AND TREES

"Mother Nature put 'em here," Ivan Puffenbarger tells a visitor who wants to know if the trees were deliberately planted. Distinguished in winter by their flaking bark and opposite branching pattern, the maples are anything but lustrous this time of year. As visitors spill from their cars into a stiff wind, most follow their noses, Iured more by the smell of maple doughnuts than by the towering stand of trees that contribute to such delicacies.

While Mother Nature put the trees here, scientists attribute human factors to their demise, which has been documented for over two decades.

The primary culprits are acid rain caused by greenhouse gases, along with the ravages of climate change: drought, heat, ice storms, and insect infestation.

Paul Schaberg, a research plant physiologist with the U.S. Forest Service, studies the influence of calcium depletion on tree health caused by acid rain and other human-related factors. His research group is studying trees on the NuPert (Nutrient Perturbation) plots at the Hubbard Brook Experimental Forest in New Hampshire. Using calcium and aluminum--which competes with calcium and lowers its availability to the trees--the scientists are studying how the balance of minerals affect the maple's growth and health.

Their work confirms other research, suggesting that it may be possible to reverse some environmental damage caused by pollution.

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"Multiple experiments concerning maple decline have shown that treating soil with calcium and/or other minerals can improve sugar maple crown condition," Schaberg says.

"Liming," using calcium to lower acidity, is already being used to protect fish populations in Adirondack streams contaminated by acidrain. The team is also investigating the effect of soil treatment on stem-wound closure.

Puffenbarger's maple stand includes 2,000 trees with 11,000 taps. Eagle has 14,000 taps. With every tap, the tree is injured. To counter the damage, producers space their taps 6 inches from where they made the hole the year before, Puffenbarger says. "It takes three years for the tree to seal itself off."

Schaberg's work has found that, with the loss of vital nutrients from the soil, the wounds are slower to heal, further exposing trees to killing forces.

While fertilizing the soil with minerals may speed the healing of stem wounds and help protect maples from stressors like the record warm temperatures of 2005, the technique is no panacea.

Rick Webb, projects coordinator for the Shenandoah Watershed Study at the University of Virginia, is doubtful that it will be widely used due to the cost. Others scientists say it's simply a patch, when what's needed are greater curbs on greenhouse gases. Dumping minerals over millions of acres of land to squelch pollution, as was done in Germany and the Czech Republic, may undermine legislative solutions requiring cleaner air.

So far, endeavors in the U.S. have been small-scale. "I don't know anyone who seriously believes that broad-scale liming is a viable solution to calcium depletion," Schaberg says. "Most of the concern is on the source of the problem--pollution--not massive fertilization projects," which will be of little help "as long as high pollution levels continue."

One thing that makes Highland County's maples particularly vulnerable is the region's high altitude. "High altitudes tend to have thinner, nutrient-poor soils," Schaberg says. "They also tend to get more precipitation, meaning more acid leaching."

Higher elevations are also disproportionately affected by climate change, studies show. "Mountain ecosystems often represent conditions not seen at lower elevations for hundreds of miles to the north," the scientist says.

As the world warms, the timberline begins to climb the mountain, seeking a cooler zone. And these ecosystems "can migrate only so far up slope before they run out of land."

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With pressures ranging from depleted soils to rising temperatures, could the maple be heading for extinction in the U.S.?

"I don't know of anyone saying that it will be eradicated as a species because of these vulnerabilities," Schaberg says, but he sounds a warning note. "Sugar maple appears uniquely sensitive to acid rain and calcium depletion. Some have speculated that it is a canary in a coal mine--a lot like red spruce, which is also declining."

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"The concern," Schaberg adds, "is that the relative dominance of this impressive and valuable species will be shifted."

That shift, some researchers predict, may abolish the U.S. maple industry by the end of the century.

As dusk falls over another maple festival in the nation's southernmost syrup country, the fortunate sugar-makers, the ones who caught the season, are worrying only about the chores that lie ahead.

Jay Eagle says he'll be up all night making candy. Tomorrow, the last day of the festival, will be just the beginning of the end. The Puffenbarger's, too, are preparing to gather the plastic tubes that sprout from their trees and snake through the woods--235 acres and 11,000 taps. That means days spent trudging for miles and bending along the steep Appalachian slopes.

Not until the maple crowns bloom and wing-shaped seeds begin to twirl will anyone around here take a rest. And that's right about the time the trees start a new cycle of their own.

As water climbs their trunks, driven by sunlight and evaporation from the new spring leaves, a process that puts water back into the air to create clouds, the maples emerge from their winter slumber. And begin making next year's sugar.

Husband and wife team Sheila and Derek Pell cover natural resource issues from Charlottesville, Virginia.

Photos by Derek Pell.