It's wait and see with leaf color

Every September there is a lot of talk about leaf color and when it will peak.  There are backyard nature lovers who turn into leaf color prognosticators, and there are those whose professions give them the edge of knowledge about such an event.

A peak in leaf turning is a misconception in the Western North Carolina mountains (WNC) because leaf turning is a season of its own spanning six to seven weeks beginning in late September and lasting into mid-November.  The kaleidoscope of leaf colors in the fall in WNC is widely varied because of the area’s diversity of 158 different tree species and varying elevations.

Western Carolina University (WCU) has a new fall leaf prognosticator, Beverly Collins.  Fall foliage forecasting is no stranger to her as a biology professor.

According to Collins the quality of the fall leaf colors throughout the region for the fall of 2016 will “depend on the temperatures recorded from September through the typical peak color weeks of October which.”

Leaves usually peak in color from Oct. 15 to the end of the month for the Swannanoa Valley area.

Sourwood, Dogwood, Maple, Sassafras and Birch trees are the first to turn red, orange and gold early in the season.  The Tulip Poplars turn yellow next, but can quickly fade to brown. The peak of the season brings the Maples with red, orange and yellow and the bright yellow of the Birch trees.  Oaks and Sweetgum trees finish off the season with purple, orange and red in their leaves.

Fall moves down the mountains like a patchwork quilt thrown over the Valley with the highest elevations showing color first.  These areas are often up to 10 degrees cooler than the Valley. Conditions in March, April and May were dry enough to put WNC into a drought.  It wasn’t until mid-to-late summer that almost daily thunderstorms relieved the drought.

Kathy Mathews, former WCU leaf color predictor, pointed out in a previous interview by e-mail in August 2015 that sugar concentrations in the leaves increase during dry weather because the trees are not absorbing as much water through their roots.  The abundance of sugars leads to the production of more red pigments that appear when green chlorophyll begins to recede.

“This is what makes the leaves really pop with color,” Mathews said in 2015.

The peak of leaf color in the high elevations around 4,000 feet arrives during the first and second week of October and by the third week of October the color is at its best at mid-elevations of 2,500 to 3,500 feet.

The lower elevations can hold its leaf colors into the first week of November, or until the leaves fall.

David Ellum, Warren Wilson College Forest director and sustainable forestry professor said that day length is the driving force behind leaf color changes.

“Lessening daylight time, shorter days, sets off the leaf turning season,” Ellum said via phone. “As the chlorophyll stops producing, two yellow pigments are revealed that were there all along.  Then the red and purples arrive in the leaves as the days become shorter and cooler.  The very best scenario would be starting in late September to have long sunny, cool days.”

Collins said whether it will be a really good year for leaf-looking, or just an average one, remains to be seen as weather observers monitor the climate to determine if the generally warmer-than-normal conditions of 2016 continue through the fall, or if temperatures start dropping and follow the patterns of a normal year.

Parker Andes, Biltmore Estate’s director of horticulture, said the dry weather returning to the region will work to produce a beautiful season.

“The summer rains have ended and it appears we are drying out and headed into the normally dry months of September and October,” Andes said.  “The National Weather Service’s long range forecasts are predicting average to below average rainfall, and that sets us up for great autumn color throughout WNC.

“We get the first hints of fall color with Dogwood and Sourwood trees, their leaves turning to dark red and maroon starting mid to late September.  With so many species of forest trees and the quick elevation change found in our mountains, the fall season is a long one.  With short day trips from Asheville visitors can experience great fall foliage color up in the higher parts of the Blue Ridge and Smoky Mountains in early October, beginning with bright yellow from birches and the oranges and reds of the Service Berry and Maples. As the month progresses, peak fall color drops down in elevation.  At lower elevations around Asheville area the best foliage color is generally found toward the end of October, and often with good color still to be seen into the early days of November.”

The Asheville office of the National Centers for Environmental Information reported that July was the 15th consecutive record warmest month globally.  State climate officials say the monthly average temperatures recorded at the Asheville Regional Airport since mid-February have ranged from slightly above normal to almost seven degrees above normal.