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Article #15,  September 1998
By Bill Cook

   Wow!  The leaf-peeper season is almost upon us!  Downstate, the “fall color reports” will be announced from TV sets in thousands of living rooms.  Northern motels and restaurants grease up their cash registers for one last flush of business before deer season kicks off the winter cycle.

   Fall is, of course, the favorite time for many people, myself included.  I’ll probably be among those who are peeping around the Keweenaw come the end of the month.  There really aren’t a whole lot of places where the brilliance of maples fill up entire landscapes.  And even fewer places if you throw the Great Lakes into the recipe for visual grandeur.  Shoot, even the Society of American Foresters scheduled their 1998 national meeting in Michigan during the color change season.

   With the dry summer across the Upper Peninsula, many people have noticed the early color changes … or at least have noticed something that actually happens every year.  Maybe a few more trees than usual have turned early, but individual trees begin to turn in late July and early August every year.  Honest!

   Red maples are often the first to be noticed because of their scarlet color.  Hard to miss as you’re driving down the highway.  These early color changes are due to major stress placed on the tree.  These harbingers of fall are exceptions, not yet the “real” thing.  Black ash normally is the first tree species to go.  They often turn a dusky yellow, but sometimes can be brilliant.  Oddly enough, it’s also one of the last trees to leaf out in the spring.  A “short-season” tree, in farmer parlance.

   Actually, the internal clock that trees use to change colors has little to do with weather.  It’s the photoperiod.  The relative number of hours of light and dark in a day.  Now, some tree species are more, or less, opportunistic.  But in general, it’s the photoperiod that affects the timing of leaf drop, not weather, or woolly bears, or bird migrations.

   However, the intensity and visual quality of the fall colors can be impacted by weather.  Drought might precipitate a more effective or quicker re-absorption of the green chlorophyll pigments.  The red, yellow, and purple pigments may stand out better, maybe for a little longer.  Frost can also have influence on the quality of fall colors, but not the timing. 

  The biggest portion of our hardwood, or broad-leaf, forests consist of maples, aspens, and birches.  The crimson and gold of maples we all know about and that pretty much beats the pants off color changes in other parts of the country.  Our aspens also turn a fantastic yellow color, with the right weather conditions.  Birch are much the same way.  A bright yellow pure paper birch stand, with snow-white bark, can be quite the inspiring experience. 

   But, let us not forget 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 to this is the glorious tamarack.  It doesn’t just lose all its needles each fall, but it does it with a blazing aurora of gold! 

   I think tamarack can provide the very finest fall show of all, under the right conditions.  When the sun is low in the west shining on a tamarack grove, and heavy, dark clouds are on the eastern horizon, the scene is enough to stop me in my tracks.  Once in northern Minnesota, I nearly hit a moose while viewing such a display.  I have since learned to pull over while driving.  And often do.  I hope that you, too, enjoy the fall this 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 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 of these articles is encouraged. Please notify Bill Cook.
By-line should read "Bill Cook, MSU Extension" Please use the article trailer whenever possible.

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