Is leaf color delayed by chronically cloudy weather? #phenology

One of the South's most noted outdoor writers, Nash Buckingham, once described the reaction of his guide to the then new-fangled thermos bottle. As I recall, Buckingham described it as something that helps keep hot things hot and cold things cold. His guide then asked "But Mr. Nash, how does it know?" I'm beginning to wonder if a similar situation is arising with the phenology of leaf color change in the North Country.

September 20, 2012. Today, still no color to speak of.

Photo by J. Harrington

The U.S. Forest Service notes that "In early autumn, in response to the shortening days and declining intensity of sunlight, leaves begin the processes leading up to their fall." If the declining intensity of sunlight is largely masked by cloudy day after cloudy day and that same pattern diminishes the difference between night and day, could our local maples, oaks and tamaracks get confused, like Buckingham's guide? Might it be that constant clouds limit trees ability to discern shortening days and declining intensity of sunlight, particularly since, in Minnesota, where hurricanes are rare, we're on our way to a record setting wet year? [Deluge pushes 2019 into second place for Twin Cities rainfall]

September 21, 2014. Today, still not much color to speak of.

Photo by J. Harrington

During the past several years, by the end of September (tomorrow), we've enjoyed considerably more color change than we're seeing this year. As the two photos above indicate, past years have shown much earlier color change than we're seeing this year. The two separate locations are in East Central Minnesota, so we get to see them weekly or so every year. If it's not the cloudiness dampening the color change schedule this year, what could it be? For some, Autumn fails as favorite season. Our perspective is "better late than never."

Autumn

By Alice Cary

Shorter and shorter now the twilight clips 

   The days, as though the sunset gates they crowd, 

And Summer from her golden collar slips 

   And strays through stubble-fields, and moans aloud, 

Save when by fits the warmer air deceives, 

   And, stealing hopeful to some sheltered bower, 

She lies on pillows of the yellow leaves, 

   And tries the old tunes over for an hour. 

The wind, whose tender whisper in the May 

   Set all the young blooms listening through th’ grove, 

Sits rustling in the faded boughs to-day 

   And makes his cold and unsuccessful love. 

The rose has taken off her tire of red— 

   The mullein-stalk its yellow stars have lost, 

And the proud meadow-pink hangs down her head 

   Against earth’s chilly bosom, witched with frost. 

The robin, that was busy all the June, 

   Before the sun had kissed the topmost bough, 

Catching our hearts up in his golden tune, 

   Has given place to the brown cricket now. 

The very cock crows lonesomely at morn— 

   Each flag and fern the shrinking stream divides— 

Uneasy cattle low, and lambs forlorn 

   Creep to their strawy sheds with nettled sides. 

Shut up the door: who loves me must not look 

   Upon the withered world, but haste to bring 

His lighted candle, and his story-book, 

   And live with me the poetry of Spring.

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