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News Release
FOR IMMEDIATE RELEASE |
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September 8, 2003 WHAT CAUSES LEAVES TO TURN? ODNR EXPLAINS THE SCIENCE BEHIND OHIO'S FALL COLOR SEASON
"Late September's cool nights and sunny days kick off a series of chemical reactions within tree leaves that cause Ohio's spectacular transition from summer to winter," said Bill Schultz, fall color spokesman with the Ohio Department of Natural Resources (ODNR). During summer months, a leaf is green thanks to an abundance of pigments in the chlorophyll family. These green pigments capture energy from the sun, using it to manufacture simple sugars that are necessary for the tree's growth. This is the process many of us know as photosynthesis. Photosynthesis steadily consumes the leaf's supply of chlorophylls, which trees replenish at a steady rate through summer months. But when days grow short and nights are cool, trees slow their chlorophyll pigment production. As demand outstrips supply, the leafy green begins to fade. That allows other pigments, which have been present in the leaf all along, to show through the fading green. These are the carotenoids, producing hues of yellow, brown, and orange.
According to Schultz, large quantities of sugar are produced in leaves during ideal weather conditions. When complemented by cool nights, the leaf's veins begin to close, preventing the sugars from being released. These conditions stimulate the production of the red and purple anthocyanin pigments, particularly in sugar-rich tree varieties such as maple, oak, sweetgum, dogwood and blackgum. When high levels of both anthocyanin and carotenoid pigments are present, leaves display the deeper oranges, fiery reds and bronzes that can light up a fall landscape. Trees now cover more than 30 percent of the Ohio landscape - up from only 12 percent in 1900. Much of that forest cover is concentrated in the eastern and southern third of the state and provides spectacular accents to the area's naturally hilly terrain. Ohio's spectacular palette of fall color stems directly from the wide variety of tree species in the state. Many are on the edges of their ranges, making for a breathtaking blend of golds, oranges, greens and reds. Ohioans and out-of-state visitors who enjoy viewing the state's fall color in a variety of locations can call the 1-800-BUCKEYE tourist information line for the latest forecast information. Internet users can find the forecast at ohiodnr.com, which also provides an opportunity to view the weekly change of seasons. The web site also gives a list of events in state parks and nature preserves, suggested fall color driving, biking and hiking routes and top opportunities to photograph Fall Color. |
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-30- For additional news online, check out the ODNR Press Room at Ohiodnr.com |
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For Further Information Contact: |
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Other colors, including reds, purples and their blends, are created by anthocyanin pigments. Unlike the carotenoids, these pigments are not present in a leaf all year and develop in sap cells by late summer.