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THE COLOR SEASON
Article #87, September, 2004
By Bill Cook
This past summer
proved to be a good growing season for trees. Unfortunately, the same cannot
be said about many vegetable gardens. Despite a lack of hot days, moisture levels
were good and no major widespread health issues occurred. Such a season sets
the stage for a potentially excellent fall color display.
Should the first
hard frost happen while the leaves retain good stocks of sugars, we could witness
one of the finest fall color shows in recent years. Color intensity is a function
of tree health and September temperatures. The 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.
Tree 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.
There 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.
While 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.
Tree 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.
The 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.
Most 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.
But, 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 warm weather.
Once 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 the summer.
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.
What new things might you discover hidden amid the kaleidoscope of fall?
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Trailer
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 cookwi@msu.edu
or 906-786-1575.
Prepared
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: cookwi@msu.edu
Use
/ reprinting
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By-line should read "Bill Cook, MSU Extension" Please use the article
trailer whenever possible.
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