A slow start to New England's fall foliage season

While the days are getting shorter and the calendar shows that autumn will arrive this week, there are significant players in the fall scene that haven't yet received the message: Trees.

Across New England, much of the forests remain a deep, verdant green, thanks to unusually warm temperatures in early September that have delayed the start to the fall foliage season, according to Marek Rzonca, the founder of The Foliage Network, which taps a network of foliage watchers to report on their region's fall color. Only a few spots in New England have even reached "low color," according to the site's latest reports.

The fall leaf-peeping season is big business across New England, with inns and restaurants banking on millions of visitors arriving from mid-September through mid-October to catch a glance at the reds, oranges and yellows that emerge at this time of year. Temperatures across New England and the Midwest will be 5 degrees to 10 degrees above normal on Wednesday, the first day of autumn, which may ensure that green remains the primary color across the region.

"With the extended warm spell we had it's reasonable to expect it will delay the onset of full color development," said Michael Snyder, the commissioner for Vermont's Department of Forests, Parks and Recreation, who is also a forester. That being said, he added, "This is very much within the historical range within variation of late summer weather and the development of fall color."

So far, inns and other businesses that rely on leaf-peepers and the green in the wallets aren't concerned, Snyder added. A spokeswoman for the Vermont tourism department said that bookings are healthy. Some tourists have already booked their trips north, and many monitor foliage-tracking sites like The Foliage Network to check on when they should jump in their cars to catch peak viewing season.

"Most of my spotters are innkeepers," Rzonca said. "They are saying, 'We're a little late, but not alarmed.'"

Trees change colors based on a number of triggers, such as waning daylight in the fall and lower temperatures. As chlorophyll pigments fade, leaves change from green to yellow, a pigment that's always present but which is covered by the green chlorophyll during the spring and summer. Some tree species, like maples, make a red pigment in response to stress, including low temperatures.

Tourists spend $3 billion annually on trips to the region during the autumn season. In Vermont alone, tourists spend $460 million annually during the leaf-peeping season, or about one-quarter of annual spending by tourists each year. Last year, tourists spent about $39 million on Vermont hotels and inns in September, a bit shy of the $44 million spent in October, according to data provided by the state.

Visitors planning trips this coming weekend may not see much color other than green, although the trees can take on their fall colors very quickly, Rzonca said.

"Because there hasn't been a broad-scale low temperature event, that green has faded only a little bit," said Paul Schaberg, a plant physiologist with the U.S. Forest Service in Burlington, Vermont. "You've seen only a little color expression but that's bound to happen when the first frost" or low night-time temperatures arrive.

Still, predicting when fall color will arrive is difficult, given the complicated interplay between temperatures, tree health and other factors. One positive sign has been what Snyder calls "an exceptionally positive spring and summer," with the type of ample sunshine and precipitation that's set up the trees for good color, assuming the other factors kick in.

"The upside of all this uncertainty is that that's one of the things that keeps leaf-peeping a bit of a challenge and a bit of an adventure," Schaberg said.