The Color Season
Article #123, September 2007
By Bill Cook
past summer was the third dry growing season in a row in the Upper Peninsula
of Michigan. Stressed trees, especially red maples, began to change color early.
However, most of the forest will proceed through the annual color change on
timing is relatively consistent, as it is controlled by a balance between dark
and light hours. This window is roughly ten days to two weeks from the end of
September and into the first week of October.
species comply, more or less, with their biological clocks, but not every species
uses the same clock. The ashes go first. Oaks will persist longer. Trees along
the Lake Superior shore have milder microclimates and often change colors at
the end of the window. Forests on the shallow soils of northern Iron County
are among the first landscapes to transform.
is a lot of biochemistry related to the annual undressing of the forest. The
process is part of what trees undergo to make themselves hardy for the cold
and dryness of winter. Northern trees have some astounding and fascinating adaptations.
timing is largely controlled by photoperiod, the intensity and visual quality
of the fall colors can be impacted by weather. The compounds with red, yellow,
and purple pigments may be brighter, or persist for a little longer, with warm
days and frosty nights. But it's a risky business to predict color change patterns.
the first hard frost happen while the leaves retain good stocks of sugars, we
should have a fine color show. Color intensity is a function of tree health
and September temperatures. The drought may soften the intensity, but the difference
will likely remain largely unnoticed.
stress might also precipitate an earlier or quicker re-absorption of the green
chlorophyll molecules. Red maples along our highways often cause comments about
an early color change. These trees are responding to unhealthy growing conditions
more than the onset of an early fall.
geography and expansive forest of the Upper Peninsula provides some of the most
colorful fall displays in the world. Annual treks by thousands of leafpeepers
provide testimony to this fact. It is a good time to be in the woods, as bird
hunters will quietly attest.
of our hardwood, or broad-leaf, forest consists of maples, aspens, and birches.
We eagerly anticipate the crimson and gold of maples, which usually outperforms
the color changes in other parts of the continent. Our aspens also turn a lively
yellow color, especially with the right weather conditions. Birch are much the
same way. A bright yellow canopy over a snow-white paper birch stand is an experience
not soon forgotten.
let us not ignore the softwoods, or evergreens. Although they do retain needles
year-round, they don't retain them all. The older needles, nearer to the trunk,
fall off every year. The only exception is the glorious tamarack. Not only does
it lose all its needles each fall, but it typically departs the season in a
flaming blaze of gold! It is the last tree to change colors as the forest bids
farewell to the growing season.
again, the much anticipated season of color change will soon lie behind us.
This time of year, many of us hold our breath, lest we miss those few days when
the forest canopy alights with the fire and brilliance of the last hurrah of
Every season hosts a multitude of changes in the forest and all that lives there, including us humans. Fall color is arguably the favorite of all seasonal changes and without doubt the outdoors is teeming with interesting events this time of the year.
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Bill Cook is an MSU Extension forester providing educational programming for the entire Upper Peninsula. His office is located at the MSU Upper Peninsula Tree Improvement Center near Escanaba. The Center is the headquarters for three MSU Forestry properties in the U.P., with a combined area of about 8,000 acres. He can be reached at firstname.lastname@example.org or 906-786-1575.
by Bill Cook, Forester/Biologist, Michigan State University Extension, 6005
J Road, Escanaba, MI 49829
906-786-1575 (voice), 906-786-9370 (fax), e-mail: email@example.com
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Last update of this page was 5 September, 2007
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