Fall foliage throughout region refreshes, renews

It’s easy to appreciate New Hampshire’s forest this time of year – few places on earth match our display of fall foliage. To add to the sheer visual brilliance, more of New Hampshire’s countryside is covered by trees than all other states in the nation, except for Maine.

Eighty-four percent of New Hampshire is forested. Most of this forest is owned by private individuals, so we owe this free spectacle to our friends and neighbors.

As summer ends, speculating about the fall foliage is a favorite New England pastime – will the foliage be better or worse than last year? Brad Simpkins, state forester and director of the N.H. Division of Forests and Lands predicts, “We will have beautiful colors this year as we do every year. Our trees are brilliant and resilient.”

Tim Fleury, Merrimack County Extension forester agrees the foliage season will be bright. “It’s been a good growing season with plenty of moisture and the foliage is green and healthy. Red maples are on track, turning red.”

“The quality and experience of color are largely determined by the weather during the foliage season, rather than by weather before it,” adds Fleury.

Fred Borman, Rockingham County Extension forester, echoes the importance of the weather during the foliage season for bringing out the color. “The key to a successful foliage season is those cool, crisp nights followed by bright sunny days with clear blue skies.”

On bright, sunny days with clear, blue skies the foliage fluoresces, reflecting light at different wavelengths than those that strike it. This produces the bright fluorescent quality for which New Hampshire’s forests are so well known.

Leaves contain a mix of pigments, each serving a different function. The most abundant pigment during the growing season is the green chlorophyll – the food-making pigment. As summer ends and autumn arrives, shorter days and longer nights signal trees to release a hormone, restricting the flow of nutrients to the leaf. This halts the food-making process, causing the chlorophyll to break down.

Fall’s brilliant color-change is mostly caused by this decrease in chlorophyll in the leaf. For the majority of a leaf’s life, the green chlorophyll is so abundant it masks the other pigments present. These other pigments are carotenoids and are responsible for the yellows and oranges we see in the autumn. Carotenoids are the same pigments that color corn, daffodils, carrots and bananas.

Cooling fall temperatures also play a role in the visual display. Anthocyanin is a red pigment produced when sugars are trapped within the leaf. This pigment colors cranberries, red apples, concord grapes, blueberries, cherries, strawberries, and plums.

Often these colors are more abundant and brilliant when the nights are cold. Sugars are made during the day and when the nights turn cold, the sugars stay in the leaf and are converted to the bright red pigment. Leaves sometimes turn from red to yellow and orange because the red anthocyanins don’t last, decomposing to reveal the other colors.

County forester Borman makes a yearly pilgrimage to the fire-tower atop South Mountain in Pawtuckaway State Park in Nottingham. “The colors are vibrant and the views are spectacular. You can see all the way from the Seacoast to Mt. Monadnock.”

According to Fleury, “The foliage season moves from north to south, starting in mid-September in the North Country and ending sometime after the peak of foliage season – usually
Columbus Day weekend in southern New Hampshire. You’re sure to find beautiful color travelling the back roads of New Hampshire.”

For advice on peak foliage areas and best routes to take, go to www.visitnh.gov and click on the foliage reports or call the N.H. Division of Travel and Tourism Development at 1-800-258-3608, starting in early September. This information is a great way to plan the perfect leaf-peeping trip.

– Karen Bennett,
UNH Cooperative Extension
Forestry Professor
and Specialist