Fall is in full effect throughout the Plateau and the mountains are dappled with yellows, oranges, purples, reds, and browns as trees brace for winter and the leaves change color.
2020 fall foliage on the Plateau:
When summer comes to a close and the days begin to get shorter, trees take that as a sign that winter is coming, said Paige Engelbrektsson, Nature Center Education Specialist, Highlands Biological Foundation. Trees then begin to cut off the flow of water and nutrients to their leaves in preparation of losing them, which is what kicks off the color change.
“Compared to tough pine needles or rhododendron leaves, the leaves of deciduous trees are easily damaged by cold conditions,” said Engelbrektsson. “It’s safer for these trees to shed their leaves every year and regrow new ones, than it is to risk losing valuable resources via damaged leaves in the winter or having their photosynthesis capability reduced come spring, let alone wiped out entirely. Anyone who has put lettuce in the freezer knows what cold can do to a leaf.”
Why the spectrum of color
During spring and summer months, deciduous trees produce chlorophyll, the pigment in leaves that gives them their green color and is necessary for producing sugars, said Engelbrektsson.
The production of chlorophyll stops in the fall. As the chlorophyll breaks down and the green color fades from a leaf, other pigments are revealed that were hidden but always present.
The yellows and oranges come from pigments called flavonoids and carotenoids.
The red colors comes from another group of pigments, called anthocyanins, said Engelbrektsson. When sugars become trapped in the leaves of certain trees, such as sourwood and oak trees, they can be converted into these red pigments.
“Much like when you mix all your colors together, brown is what’s left after all the pigments have broken down,” said Engelbrektsson.
Why are some fall seasons more “brilliant” than others
Engelbrektsson said the consensus among experts is that fall colors are generally influenced by the environmental conditions during September.
Colors are projected to be “brighter” if conditions during early fall, September and early-October, stress the trees. Stressful conditions include dry and sunny days, and cold nights.
Engelbrektsson added that the mild conditions throughout September 2020 were not the type of stressors to prompt a sudden and bright color change, especially with warm nights and plenty of rain.
Learn more about fall colors from Engelbrektsson in a video HERE.