Leaf-color predictor perfected

Chlorophyll production will drop sharply throughout the northern hemisphere in the third quarter of 2004, according to analysts who have tracked deciduous plant growth over the past 67 million years.

Barring collision with an asteroid, this year will be no different — despite a late summer ramp-up of hurricane activity.

With diminution of green pigment, bit-players in leaf chemistry will enjoy their moment in the sun. Carotene (yellow), xanthophyll (orange) and anthocyanins (red) come to the fore.

Of these, the anthocyanins, which are water soluble, are most affected by changing weather conditions. Production is increased by a succession of cool nights and sunny days, while the color can be leached out by excessive moisture during the color shift.

All projections about the physical changes that might occur in leaves during any given fall season are conjectural. Botanists note, however, that heavier rain in late summer is likely to delay the color change a little.

According to Wayne K. Clatterbuck, an assistant professor of Forestry, Wildlife and Fisheries at the University of Tennessee, “As days become shorter and nights grow longer, biochemical processes in the leaf initiate changing leaf color. All the other factors vary annually, making the prediction of autumn color unreliable.”

This year, as always, the changes are already visible at higher elevations, with individual trees on lower ground jumping ahead of their companions in sudden bursts of color. Due to this vertical flux, leaf season in the Southern Appalachians lasts for as long as six weeks, while flatlanders watch the shift rush past them in one-third the time.

Far more accurate than building expectations on the predictably inaccurate musings of the Old Farmer’s Almanac or self-appointed plant experts, is to look at oneself in the mirror. Laugh lines? Crows’ feet? A touch of silver on the temples? If this describes you, then this autumn’s show will be magnificent.

According to comprehensive studies done over many decades, our perception of blues and greens and the ability to discriminate between these “cool” colors fades as we age. Therefore, the contrast between warm colors (yellow, orange, red) and a deep-blue autumn sky is comparatively greater than the contrast between the myriad leaf-greens of summer and the paler summer sky. (Due to the changing angle of the sun, daytime blues are deeper in fall and spring.) Thus the apparent shift of color becomes greater as we age.

Plus, most of us grow happier and happier to have lived another season, and more and more aware of how quickly they fly by.

So, my official and absolutely accurate prediction for this fall? Best ever.

If you don’t agree, then grab your dismal expectations by the scruff of the neck and give them a good shake. Go for a walk, a bike ride, even a drive (but please use the most efficient vehicle available — pollution is enemy numero uno to trees) and let it all in. The carotene, xanthophyll and anthocyanins will never be this way again.

Nor will you.

Look before you leaf

Leaf-lookers are well advised to check on road conditions if planned drives are time-critical. Following the double whammy of Frances and Ivan, many bridges are out for the count and sections of the Blue Ridge Parkway are missing. For up-to-date info check out the NCDOT Web site: http://apps.dot.state.nc.us/tims/RegionSummary.aspx?re=7.