Just last week, Vermonters in many parts of the state were still looking at the green leaves of summer, with some even browning prematurely due to a long span of unseasonably hot weather. But over the weekend that changed quickly, according to Mike Snyder, Commissioner of Vermont's Department of Forest, Parks and Recreation. His department puts out the state's weekly fall foliage report.
"As of last week, there were still large volumes of very green leaves throughout the state with pockets of the early wave of foliage that had passed and was not followed by what's normally the second and third and final act and that was causing some angst and concern. People kind of wondering if it's a bust. And then quite literally over a couple of days last week in most parts of the state it just turned and it popped," Snyder said.
A lot of the science on the physiology and biology of fall color and how trees interact with their environment has come from research done in Vermont, but Snyder said, there's still more to learn. "There remains some mystery, call it magic if you will. And I personally think that's a wonderful part of it."
"The trees know what they're doing and they've been doing this dance for a long time with the weather and site conditions. They can't get up and move around. They are programmed to deal with variable conditions and to take cues from the environment, like waning day length in August triggers the onset, the initiation of this whole process of getting ready for winter. And then there's another cue from the environment which is cold weather during the fall season, the sort of last ingredients in this process for the dazzling display and that part just didn't happen, it was delayed," he explained.
Trees continued to take advantage of some unseasonably warm temperatures to keep the green-pigmented chlorophyll in their leaves for a few more weeks as they prepared for winter. It's when they shut down the process of photosynthesis that the bright colors emerge.
Snyder says in high elevations and the north, the season is pretty far along, but on the western side of Vermont from Franklin County down to Bennington county, there are still more fall colors to come. In the Central part of the state, colors are peaking, and in the east and Connecticut River valley, there is also still more foliage to come, as long as the weather stays calm.
"Keep in mind it's always the caveat every year that things can change very quickly. So heavy rain with wind can strip the leaves. We have had snows at lower elevations in October," Snyder said.
And climate change continues to be a concern when talking about the health of Vermont's forests. "You see [climate change] in the way forest plants respond to say, timing of flowering and bud break in the spring. It's not the normal pattern and the trees reflect that and they're telling us by this sort of goofy, delayed and now wonderful fall foliage season. I think that's a sign," Snyder said.
Forests are one of the best mitigating tools against climate change because they absorb carbon dioxide in the atmosphere and can improve flood resilience, but they are also vulnerable, Snyder said. "The good news is again trees are good at dealing with environmental change but the pace of change that we're seeing now far outstrips what they've evolved with. And that's of deep concern."