The autumn palette
By Courtney PottsSpecial to the Journal | Posted: Monday, October 08, 2007
Each fall, hordes of "leaf peepers" flock to Vermont to enjoy the fall foliage. Siouxland residents, however, can save themselves a trip. All they have to do is step outside their front doors.
With many yellow and orange leaves already visible, experts from Iowa's State Forest Nursery in Ames expect leaf displays throughout Iowa to be at their best by this coming weekend.
"We usually see, over a long period of time, the weekend closest to the 10th of October is the peak weekend," said Randy Cook, state urban forestry coordinator for the Iowa Department of Natural Resources.
Bright reds and oranges in most regions should reach their peak sometime between Oct. 10 and 13 and remain vibrant for four to five days longer.
One popular spot for local leaf peepers is the Loess Hills National Scenic Byway, which stretches for 220 miles from Plymouth County in Northwest Iowa to the Missouri border. Barbara Ford, interim tours coordinator for the Loess Hills Hospitality Association of Moorhead, Iowa, recommends that visitors searching for spectacular views try the scenic overlook in Preparation Canyon State Park, five miles south of Moorhead off state Highway 183. However, she added, any of the byway's many scenic loops are likely to please at this time of year.
"It's just a beautiful drive," Ford said. "I encourage anybody to stop by."
David Zahrt, owner of the Country Homestead Bed and Breakfast in Turin, Iowa, and a proponent of prairie restoration, encourages his guests to check out a different type of fall color.
"What I see mostly is the golden brown of the prairie grass. It's the best foliage to see, as far as I'm concerned," Zahrt said.
If the colors seem duller than usual this year, blame the weather. Cold temperatures in the spring and higher than average rainfall throughout the summer created poor conditions for foliage. According to data from the National Weather Service, this summer was Sioux City's wettest in more than a decade. The result is that some areas, especially in central Iowa, are not expected to see a foliage peak for another two weeks, and others may have less-than-spectacular shows.
"It isn't going to be just a super striking year, but I think it'll be in the top 50 percent," Cook said.
Why do leaves change color?
As Karen L. Koster, professor of biology at the University of South Dakota, explains it, leaves serve as a tree's "factories." They convert sunlight and water into sugar through the process of photosynthesis, and the sugar is then transported throughout the plant. For trees, preparing for winter means shutting down their factories.
"As the days get shorter and the nights get longer, the plant senses that transition," Koster said. "And at a certain point, most plants will begin to cut off their leaves."
A special layer of cells is created to separate the leaf's stem -- or "petiole" -- from the rest of the tree. This layer traps sugar in and keeps water out. At the same time, chlorophyll -- the green pigment that gives leaves their color in the spring and summer -- starts breaking down.
"As the green color begins to break down, then we can see all the other pigments in the leaf," Koster explained.
These pigments include xanthophyll (yellow), carotenoids (orange), and anthocyanins (red).
Anthocyanins are created by the breakdown of excess sugar and are the most likely to be affected by the weather.
"If you have bright, sunny days (in the autumn), you'll have more red," Koster said, "because there's more sugar made."
For all that biologists know about how the process works, they still don't have a definite answer for "why?" Fall colors may protect leaves by acting like sunscreen or repelling insects, or they may serve no purpose at all.
"There are still a lot of mysteries out there for us to think about and enjoy," Koster said.
With many yellow and orange leaves already visible, experts from Iowa's State Forest Nursery in Ames expect leaf displays throughout Iowa to be at their best by this coming weekend.
"We usually see, over a long period of time, the weekend closest to the 10th of October is the peak weekend," said Randy Cook, state urban forestry coordinator for the Iowa Department of Natural Resources.
Bright reds and oranges in most regions should reach their peak sometime between Oct. 10 and 13 and remain vibrant for four to five days longer.
One popular spot for local leaf peepers is the Loess Hills National Scenic Byway, which stretches for 220 miles from Plymouth County in Northwest Iowa to the Missouri border. Barbara Ford, interim tours coordinator for the Loess Hills Hospitality Association of Moorhead, Iowa, recommends that visitors searching for spectacular views try the scenic overlook in Preparation Canyon State Park, five miles south of Moorhead off state Highway 183. However, she added, any of the byway's many scenic loops are likely to please at this time of year.
"It's just a beautiful drive," Ford said. "I encourage anybody to stop by."
David Zahrt, owner of the Country Homestead Bed and Breakfast in Turin, Iowa, and a proponent of prairie restoration, encourages his guests to check out a different type of fall color.
"What I see mostly is the golden brown of the prairie grass. It's the best foliage to see, as far as I'm concerned," Zahrt said.
If the colors seem duller than usual this year, blame the weather. Cold temperatures in the spring and higher than average rainfall throughout the summer created poor conditions for foliage. According to data from the National Weather Service, this summer was Sioux City's wettest in more than a decade. The result is that some areas, especially in central Iowa, are not expected to see a foliage peak for another two weeks, and others may have less-than-spectacular shows.
"It isn't going to be just a super striking year, but I think it'll be in the top 50 percent," Cook said.
Why do leaves change color?
As Karen L. Koster, professor of biology at the University of South Dakota, explains it, leaves serve as a tree's "factories." They convert sunlight and water into sugar through the process of photosynthesis, and the sugar is then transported throughout the plant. For trees, preparing for winter means shutting down their factories.
"As the days get shorter and the nights get longer, the plant senses that transition," Koster said. "And at a certain point, most plants will begin to cut off their leaves."
A special layer of cells is created to separate the leaf's stem -- or "petiole" -- from the rest of the tree. This layer traps sugar in and keeps water out. At the same time, chlorophyll -- the green pigment that gives leaves their color in the spring and summer -- starts breaking down.
"As the green color begins to break down, then we can see all the other pigments in the leaf," Koster explained.
These pigments include xanthophyll (yellow), carotenoids (orange), and anthocyanins (red).
Anthocyanins are created by the breakdown of excess sugar and are the most likely to be affected by the weather.
"If you have bright, sunny days (in the autumn), you'll have more red," Koster said, "because there's more sugar made."
For all that biologists know about how the process works, they still don't have a definite answer for "why?" Fall colors may protect leaves by acting like sunscreen or repelling insects, or they may serve no purpose at all.
"There are still a lot of mysteries out there for us to think about and enjoy," Koster said.
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peeper wrote on Jan 22, 2008 3:22 PM:
Todd wrote on Oct 14, 2007 5:43 PM:
Steve wrote on Oct 9, 2007 2:57 PM:
Neil wrote on Oct 8, 2007 12:30 PM: