Neighborhoods in southeast Michigan and northwest Ohio are aglow with the amazing fall foliage transformation. This past weekend, my13ABC weekend co-anchor, Tony Geftos, said he has heard that little fairies and gnomes are behind the changes and they spread their magic throughout the land in the fall to help the leaves on the trees change into wonderful colors.
Nice fairy tale, Tony. All kidding aside, we know that the leaves are reacting to the tree's natural process for winter hibernation. We are the lucky recipients of a beautiful show of color throughout the next month.
How it works
So what's the science behind it all? Shorter days are a trigger. The best leaf-turning weather is to have bright days and cold nights.
As a meteorologist, I can tell you that the lower sun angle and shorter days cause a chemical change in plants. Leaves start to turn colors because they get less sunlight. The upcoming forecast with highs in the mid 60s to low 70s and lows between 35 and 50 degrees will keep those colors changing.
Usually you will see beech, hickory, and birch leaves turn yellow, orange and brown. They turn these colors because their chemical leaf structure contains carotenoid pigments. Trees that have a lot of sugar in them such as sweetgum, dogwood, maple, and oak will turn red and purple. They have anthocyanin pigments in their leaves and will turn darker colors.
Yellows come from xanthophyll pigments and the brown colors are usually the end of the road. These are the tannins in the plant and are considered its waste product.
Your trees aren't the only ones going through changes right now. Garden plants such as purple grapes, violets, beets, and red apples also contain anthocyanin pigments.
When you grow yellow pansies, hollyhocks, and carrots, they get their yellow coloring from the xanthophyll pigments just like the leaves on a tree. Scientists think these pigments protect the plant from the sun sort of like sun screen because the sugar in those pigmets lowers their freezing point and also gives them a bit of frost protection.
Roger Mech, Forest Health program manager for the Michigan Department of Natural Resources, said color changes are subjective.
"The vividness of the colors may not be as bright because of the drought, but it just depends on the site," he said. "I don't think the season's dry conditions really affect how quickly the trees change color, but rather the brightness of that color."
Mr. Mech said the northern hardwood trees have just passed their peak color season and central Michigan is at peak right now.
"In the big picture, you don't see a lot of change in the peak of colors," he said "It is hardly enough for folks to notice. A lot of it also depends on a bright sunny day versus an overcast day because the colors will look much more vivid on a bright day, rather than an overcast, dreary day," he said.
Southern Michigan and northern Ohio are about a week or two from their peak color season, with all general areas holding their color for three or four weeks before the high winds blow the leaves to the ground. Check out this Web site from the United States Department of Natural Resources: na.fs.fed.us/fhp/pubs/leaves/leaves.shtm.
Contact Kelly Heidbreder at firstname.lastname@example.org.
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