Turning leaves
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- October
- 9
Want to know why trees lose their leaves and why forests go the technicolor route come fall? Here’s a good explainer from Audubon magazine:
But first, why do deciduous trees drop their leaves? Jeffrey A. Simmons, an environmental scientist at Mount St. Mary’s University in Emmitsburg, Maryland, had a concise explanation for me. “Leaf shedding was forced on deciduous trees if they wanted to survive winter,” he said. Conifers are able to ignore snow, ice, and harsh cold because their leaves, or needles, have a small surface area and the cells contain an antifreeze, Simmons explained. Maples, oaks, birches, hickories, and such, on the other hand, have broad leaves that would be severely frost-damaged by repeated freezing and thawing.All of those autumn leaves, naturally, were once various shades of green because of chlorophyll pigments that effectively mask any other color pigments present in the leaf cells throughout the long growing season. The job of chlorophyll is to take energy from the sun and use it to manufacture sugars—the carbohydrates trees need for growth and development—from carbon dioxide and water. Photosynthesis hard at work. Since chlorophyll breaks down in the process, it is constantly replenished until autumn approaches, bringing shorter days and cooler nights. As sugar production slows and the supply of chlorophyll dwindles, those hidden pigments begin to appear. These are the carotenoids (as in carrots) that reward us with the wide range of yellow, orange, and brown hues.
The above article also tackles the issue of fall color and climate change.
For a look at where the color is, you can check out the foliage map put out by Yankee magazine. While New England-centric, the map dribbles over into the Hudson Valley.
This entry was posted
on Friday, October 9th, 2009 at 11:43 am by Mike Risinit.
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Journal News staff writer Greg Clary writes Earth Watch, reporting on environmental issues in the lower Hudson region. Clary has been a reporter, editor and columnist at the Journal News since 1988 and has covered police and courts, transportation, municipal government, development and the environment in the Lower Hudson Valley, among other topics. 
Laura Incalcaterra covers the environment, open space and zoning and planning issues for The Journal News. A Boston College graduate, Laura grew up in Rockland, attended East Ramapo schools and has worked for The Journal News since 1993. Laura has written features and covered North Rockland, crime, government and a host of other issues.
Mike Risinit covers Patterson and Kent in Putnam County, as well as environmental topics touching on the Hudson River and the Great Swamp. Risinit has been a reporter at The Journal News since 1998.
