By Peter Oliver

Vermont. Fall. Foliage. Those three words converge with such symbiotic unity that they essentially become a consuming definition of life in the state in late September and early October. For all of Vermont’s fame as a state renowned for skiing and its powerful skiing economy, the busiest period for tourism is late summer and fall. Inns fill, camera shutters snap, and restaurants do a brisk business.
Of course it is tourism in a very different form than what consumes the winter months. Foliage tourism activity isn’t concentrated at ski areas. There are no lift lines. Instead, visitors fan out broadly, through the Mad River Valley and the rest of the state, in search of the best view — perhaps the single most vibrantly hued tree — that can take a person’s breath away.

That’s the simple part of the story. More complex are answers to a few basic questions. What exactly happens to bring on this magical transformation in the leaves of trees? Why? When? Why are some years more colorful than others? There are a few reliable scientific explanations, but, despite what naturalists or veteran Vermonters might try to tell you, the answers can be summed up as follows: Nobody really knows for sure.

A quick bit if chemistry class, then. Chlorophyll, the chemical that makes leaves appear green most of the summer, basically turns sunlight into food that gives trees the sustenance they need to grow and thrive when the weather is warm. But when sunlight intensity ebbs in the fall, the production of chlorophyll correspondingly diminishes. With that, other pigments in leaves, produced by such chemicals as carotenoids and anthocyanins, start emerging as reds, oranges, yellows, pinks, and purples.

All of that is inevitable chemical certainty. Thereafter, variability and the annual foliage guessing game take over. Will this be a good year for foliage? When will the peak time arrive? Obviously, climatic circumstances, varying from one year to the next, play a role in answering those questions. Less variable, perhaps, are soil conditions and the basic genetics of any particular tree or any particular tree species. Even so, the same tree living in the same soil through similar weather conditions can draw from an entirely different palette from one year to the next. Go figure.

A prevailing theory is that the seasonal combination of a warm and wet spring, a more-or-less average summer, and a fall in which temperatures cool at night but don’t go below freezing produces the best foliage. But again, who really knows for sure?

Birch and poplar trees, which turn almost exclusively yellow, are somewhat more predictable, but with maples, anything can happen. A big part of the marvel of fall foliage is that it can leave human rationality in the lurch – much of what happens is brought on by natural mysteries that surpass mortal understanding.

That said, what can you do to experience the Mad River Valley’s foliage display at its glorious best? Step One is timing. There is no shortage of information, through various means of reporting, to stay up-to-date on prevailing foliage conditions on an almost minute-by-minute basis. Weather outlets, like the Weather Channel, follow foliage conditions with the unstinting fervency with which they follow hurricane activity. At least two web sites, and, do nothing but report on foliage conditions. A rule of thumb is that peak foliage usually comes in the first week in October, but it varies from year to year. Plan your travels accordingly.

Step Two is finding a sweet viewing spot. Every Valley resident or visitor no doubt has a favorite tree. But for a few choice spots, here goes: Along the Sugarbush golf course, the colors and the lay of the land on the 10th hole usually produce a particularly vibrant display. For a broader panorama, the seventh tee is the place to be. Nearby, ancient maples that line Golf Course Road and West Hill Road can provide an inspiring backdrop to an easy walk, run, or bike ride.

Several points on the Mad River Path near the river can be great, especially in the morning when mist is often rising off the water. The combination of cooler air and humidity near the river tends to accelerate the color transformation. Both Sugarbush and Mad River Glen offer lift rides on weekends through the foliage season, although keep in mind that above about 2,400 feet you leave the hardwood trees like maples and birches and enter the conifer zone, consisting mostly of spruces and hemlocks, where greens and browns persists into winter.

And every year, some tree somewhere seems to decide to become a peacock, bursting with a multiplicity of colors that shames its neighbors. It happens without discernable or explicable reason. That’s Vermont foliage at its best, where nature’s beauty and its unfathomable mysteries merge to such inspiring effect.