Some trees are displaying bright fall colors early in Maine this year, which may mean an extended fall foliage season. These pops of color in late August are being attributed to the drought that has affected much of Maine this summer.
“What we’re seeing is some early fall coloration, and that’s due to the trees being under a bit of stress,” said Aaron Bergdahl, forest pathologist with the Maine Department of Agriculture, Conservation and Forestry. “Some species are going to be exhibiting some nice colors several weeks earlier than normal.”
However, not all trees in Maine’s millions of acres of forestland are affected equally by the drought, Bergdahl said. It’s trees by the roadside, along the edges of forests and in people’s yards that are most likely to dry out and tap out early due to exposure and shallower roots, ceasing their production of chlorophyll, the source of green in leaves.
“A lot of people are noticing it from the windows of their cars,” Bergdahl said. “They’ll see one maple already blazing red and orange and it’s striking. I’ve been getting some inquiries here at the office about it.”
Fall foliage season in Maine typically begins mid-September and lasts until mid-October, with slight variations every year, depending on weather. In addition, the leaves start to turn colors in northern Maine about a week before the southern reaches of the state. This pattern is fairly consistent from year to year, according to statewide fall foliage reports collected and compiled by the Maine Forest Service for nearly 60 years.
“We’re generally reaching peak conditions in most areas right around Columbus Day weekend, which is a very popular weekend for folks from away to come check out the foliage,” said Gale Ross, who has served as the fall foliage spokesperson for the Department of Agriculture, Conservation and Forestry for 15 years, helping people enjoy Maine’s flashiest season.
Working with Maine forest rangers, Ross compiles weekly reports throughout fall foliage season, emailing them each Wednesday to subscribers and posting them on Facebook and the state-run website, mainefoliage.com. This year’s first report lands on Sept. 12.
“I reach out to the forest rangers in seven zones,” Ross said. “They give me their on-the-ground observations [and photos], and from that we build the report and the map.”
“You can pretty much be assured that the foliage is going to progress from north to south, with zones 6 and 7 [in the north] reaching peak right around the end of September and the rest of the state following suit in the first week of October,” Ross said.
Despite the early pops of color throughout the state this year, Bergdahl expects the timing for peak fall foliage to remain the same as years past because while some trees have been affected by the drought, most have not.
“I don’t think there’s going to be a peak shift,” he said. “In the forest, the trees are deeply rooted and able to access water. It’s really the edges where you’ll see more of the stress-related coloration [early in the season].”
Another factor that may affect this year’s fall foliage is the brown-tailed moth, which has rapidly expanded its territory throughout midcoast Maine this summer. This forest pest hatches during August or early in September to feed on the leaves of many different types of hardwood trees and shrubs. Their most common hosts are oak, apple, crabapple, cherry, hawthorn, shadbush, serviceberry and rugosa rose, according to the Department of Agriculture, Conservation and Forestry.
“Oaks are very nice [fall foliage trees] but the trees I think people really respond to are the maples and there are no major defoliators active in the state this year that impact maple trees,” Bergdahl said.
While fall foliage may have a bit of a head start this year, Maine State Climatologist Sean Birkel said that long term — looking at decades rather than years — fall foliage may come increasingly later due to rising fall temperatures.
Birkel, who is also an assistant professor at the Climate Change Institute at the University of Maine in Orono, has recently been occupied with compiling Maine temperature and precipitation records dating back to 1895, and that data shows that over the course of over 100 years, Maine’s average temperature in September has increased steadily, and more noticeably in the past 20 years. For instance, the average temperature for September in 1997 was 43.1 degrees Fahrenheit, while Maine experienced its hottest September on record last year, with an average temperature of 48.5 degrees Fahrenheit.
But fall foliage is affected by more than just temperature, so it’s difficult to predict what will happen with the leaves from year to year.
“It’s a complex process because it involves the daylight length, overall precipitation, and it could also link to nighttime low temperature versus daytime high temperature,” Birkel said.
Triggered by all of these factors, leaves change color when a tree stops producing green chlorophyll, revealing yellows and oranges from carotene and xanthophyll. And at the same time, some leaves also undergo chemical changes that produce anthocyanins, which paints the leaves red or even purple or blue.
But for that to happen, the temperature needs to drop, and the National Weather Service has predicted that Maine and the rest of New England will experience above average temperatures this September.
“According to weather forecasting, the first part of September is going to be warm days and warm nights, and we really need cool evenings to start that progression of foliage turning,” Ross said. “It’s Mother Nature’s way of putting our trees to bed. It’s going to happen, ready or not.”
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