Fall: The colorful changing leaves

By MSN News: Charles W. Jones of MSN News | AP Photo: Jim Cole, File
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White Mountain National Forest

The fall season brings a colorful display of leaves. Here's a look at some of America's foliage-viewing destinations and the process a leaf goes through as it dies. See gallery

Peak fall foliage colors in the White Mountain National Forest in Twin Mountain, N.H.

For a small state, New Hampshire offers a variety of free experiences in the fall, whether it's scenic drives, hiking, moose watching, browsing antique shops or spotting huge pumpkins. The state's tourism division started a new campaign this year, "Live Free and ...." The fill-in-the-blank play on the state motto, "Live Free or Die," suggests there are many possibilities when it comes to exploring New Hampshire.

Redux: Berthold Steinhilber, laif
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Berkshires at Mount Greylock

Colorful forests of the Berkshires at Mount Greylock in Massachusetts.

Getty Images: Cyrus Mccrimmon
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Rocky Mountain National Park

The leaves are starting to turn at Rocky Mountain National Park in Colorado, as seen from the Bierstadt Lake Trail, Sept. 20, 2005.

Landov: Butch Dill
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Smoky Mountains National Park

Fall colors along the Little River in Smoky Mountains National Park, Tenn.   
 

Getty Images: Mladen Antonov, AFP
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Shenandoah National Park

The Blue Ridge Mountains emerge from the morning fog, as seen from Skyline Drive in Shenandoah National Park, Va., Oct. 25, 2012. 

AP Photo: Pat Wellenbach
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Acadia National Park

Colorful fall foliage appears to be near its peak in Hancock, Maine, with the mountain tops of Acadia National Park seen in the background, on Oct. 9, 2007. 

Redux: Julie Keefe, The New York Times
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Columbia River Gorge

Stands of hardwood trees are seen near Horse Tail Falls in the Columbia River Gorge, east of Portland, Ore., Oct. 13, 2007.

AP Photo: Toby Talbot, File
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Green Mountains, Vt.

A farmer chops corn in front of a hillside of color in Richmond, Vt.

Vermont officials are rushing to the defense of one of the state's most cherished icons, fall foliage, after an Arizona magazine claimed the fall colors in the Grand Canyon state are better than the Green Mountains after they have turned red, gold and orange. The cover of the October edition of the magazine Arizona Highways shows a picturesque scene of a bucolic waterfall surrounded by golden foliage, with the headline "Autumn in Arizona & why it's better than it is in Vermont."

Getty Images: Visions of America, UIG
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Michigan's Upper Peninsula

Autumn color at Porcupine State Park, in Michigan's Upper Peninsula.

Landov: Mike Greenlar, The Post-Standard
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Adirondack Mountains, NY

Fall foliage surrounds a pond along Route 28 in Old Forge in the Adirondack Mountains, N.Y. 

MCT: Kate Nieland, Chicago Tribune and Steve Thomas, St. Paul Pioneer Press, South Florida Sun-Sentinel
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How leaves work

In a green leaf, the chemical chlorophyll uses sunlight energy to combine water and carbon dioxide into glucose. The blue and orange parts of sunlight are converted into energy that the tree uses for growth.

 

Sources: U.S. National Arboretum, State University of New York College of Environmental Science and Forestry, McGraw Hill Concise Encyclopedia of Science and Technology, Simply Science, The Plant Doctor, U.S. Forestry Service
 

MCT: Kate Nieland, Chicago Tribune
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Changing color

When chlorophyll is abundant in leaves, the green color covers up other pigments. The other colors that were present but blocked by the green become visible when there is a lack of chlorophyll.

 

Yellows and oranges
These pigments are made by xanthophylls and carotenoids (the same as in carrots) and absorb the green light the cholorophyll misses.

Reds and purples
Some leaves turn red from anthocyanins, a chemical manufactured from the sugars trapped in the leaf.

Browns
When all the pigment breaks down, only the brown tannins remain.

 

Sources: U.S. National Arboretum, State University of New York College of Environmental Science and Forestry, McGraw Hill Concise Encyclopedia of Science and Technology, Simply Science, The Plant Doctor, U.S. Forestry Service
 

MCT: Steve Thomas, St. Paul Pioneer Press, South Florida Sun-Sentinel
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Color changes in fall and winter stages

Early autumn: Chlorophyll breaks down and reveals leaves' yellow, orange and red pigments.

Mid-autumn: The tree draws nutrients from leaves and roots; chemical changes in leaves create different colors.

Late autumn: Leaves are drained of nutrients, and photosynthesis stops; tree sheds its leaves.

Winter: Reabsorbed nutrients help tree survive the weather.

 

 

Sources: U.S. National Arboretum, State University of New York College of Environmental Science and Forestry, McGraw Hill Concise Encyclopedia of Science and Technology, Simply Science, The Plant Doctor, U.S. Forestry Service

Steve Thomas, St. Paul Pioneer Press, South Florida Sun-Sentinel
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Why leaves fall: Process

The process that stops chlorophyll production also makes leaves fall.

1. At the end of each leaf stem, small tubes carrying water to the leaf and glucose back to the tree pass through a layer of specialized cells.

2. In autumn, the layer's cells swell and cut off the tubes.

 

Sources: U.S. National Arboretum, State University of New York College of Environmental Science and Forestry, McGraw Hill Concise Encyclopedia of Science and Technology, Simply Science, The Plant Doctor, U.S. Forestry Service

Steve Thomas, St. Paul Pioneer Press, South Florida Sun-Sentinel
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Why leaves fall: Process

3. The layer seals off the stem from the leaf, and its cells break down.

4. The weakened leaf falls or is blown from the branch.

 

Sources: U.S. National Arboretum, State University of New York College of Environmental Science and Forestry, McGraw Hill Concise Encyclopedia of Science and Technology, Simply Science, The Plant Doctor, U.S. Forestry Service

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