By Eilís Donohue, SCA Interpretive Ranger at Franconia Notch State Park
When you think of the quintessential autumn—crisp air, blue skies, trees ablaze with shades of red, orange, and yellow—chances are you think of New England. While it’s still mid-September, and fall foliage is just beginning to emerge in most parts of New Hampshire, now is the time to look ahead and make a plan if you don’t want to miss peak colors. Fall can go by in a flash, so be sure to make the most of it!
Before we get into the coveted details of when and where in New Hampshire to see those leaves—and I promise I’ll get to that—let’s explore the mystery of fall foliage first. Why do leaves turn such brilliant colors in the fall? The answer lies in the chemis-tree (get it?).
In the spring and summer, trees’ leaves are green, as are many other plants, because they are actively going through photosynthesis: the process of turning carbon dioxide, sunlight, and water into sugars that feed the tree’s growth. The pigment chlorophyll plays a large part in that equation; it takes the sunlight streaming over the leaves and converts it to energy. It is also responsible for that beautiful, healthy green color, in everything from the oak tree in your backyard to the okra on your plate.
Chlorophyll is just one of several pigments found in leaves, however. As temperatures drop, chlorophyll begins to break down, making room for the other pigments to shine. The broken-down chlorophyll pigment turns leaves brown; carotenoids (like in carrots) and xanthophylls create orange, yellow, and sometimes brown hues. Anthocyanins create red, and actually indicate a high sugar content in the leaf. The leftover sugar in the leaf is turned into anthocyanin, and when all of that sugar is depleted, the anthocyanin dissipates and other pigments arise to turn the formerly red leaf a different hue. When all of the other pigments run dry, the ever-present tannins turn the dead leaf brown (tannins are also responsible for the dark color and bitter taste of tea and red wine).
Why does chlorophyll break down, though? When the weather begins to turn cold, and the hours of sunlight per day start dwindling, a tree has to cut corners to stay alive. Like many plant and animals that live in regions where the winters are harsh, they become dormant. That means it can’t afford to keep its leaves fresh and green, because they use up energy that the trunk and roots could be storing for next year.
So the tree cuts the leaves off from the source by growing an abscission layer, a corky layer of cells between the leaf and the branch. Without being connected to the mainline of the tree’s flow of sap and nutrients, the leaves begin to die, and with them, the chlorophyll. Some tree species grow their abscission layer earlier or later than other species; this is the reason you may still see brown oak or beech leaves clinging onto branches in the dead of winter. Younger trees also tend to hold onto their leaves longer than older ones do.
Temperature, amount of sunlight, and precipitation can all affect the brilliance of the leaves’ colors from year to year. The boldest colors—usually including lots of red from those anthocyanins—can be seen during a fall season with warm sunny days and cool nights. A very dry summer or fall can reduce the brightness of the colors.
So now you know the science behind those dazzling leaves, you’re surely even more excited to get a good look at them! Want to know when and where you’ll have the best chance? VisitNH.gov has a fun interactive map of predicted fall foliage in different regions of the state; check it out here: https://www.visitnh.gov/foliage-tracker. Based on this map, peak leaf season here in the White Mountains will probably begin in about a month, around mid-October. In case you’re not in New Hampshire, plenty of other states and regions have their own online foliage trackers.
Looking for a more active way to enjoy the foliage? Here are a few ideas:
- Take a hike! Fall weather can be ideal for hiking; just make sure you pack some extra layers for when the air gets chilly. If you’re up here in Franconia Notch, try hiking up Bald Mountain/Artists’ Bluff to get a gorgeous view of the notch for relatively little effort. Or take the Cannon Mountain Aerial Tramway up to the peak of Cannon to get panoramic views of Franconia Notch, and even all the way out to Maine, Vermont, and Canada on a clear day.
- Go for a bike ride! The Franconia Notch recreational trail passes through about 9 miles of woods that are sure to be full of gorgeous color in a few weeks. Check out other bike paths near you!
- Kayak or canoe. Bundle up, bring some snacks and a thermos full of warm coffee, and head out in a boat to enjoy the foliage around a lake, pond, or river near you.
- Drive along a scenic route. Here in the White Mountains, the Kancamagus Highway is pretty much the best of the best—34 miles of uninterrupted forest, and several vistas along the way to stop, stretch your legs, and take pictures. Check out a list of scenic highways and byways in every region of the state here: https://www.visitnh.gov/trip-ideas/scenic-drives.
- Check out this list of cruises, train trips, tours, and more opportunities to bask in the glory of fall right here in New Hampshire: https://www.visit-newhampshire.com/state/70-great-things-to-do-in-new-hampshire.
- Take a walk in your neighborhood. Just get out there and enjoy the season while it lasts!
Happy leaf peeping!
References:
- https://www.esf.edu/pubprog/brochure/leaves/leaves.htm
- https://askabiologist.asu.edu/questions/why-do-leaves-change-color
- https://www.fs.fed.us/fallcolors/2015/science.shtml
