Virginia Tech forestry expert explains when and where to see the best fall foliage

Published: Oct. 26, 2020 at 7:00 AM EDT
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ROANOKE, Va. (WDBJ) - The trees across southwest Virginia are showing off their fall colors. Across WDBJ7′s hometowns, AIR7 captures the magnificent colors of autumn, from Roanoke County to Giles County, with plenty of landscape in between.

“When you go up in the Blue Ridge Mountains, you’re up, you’re down, you’re all around and that changes the tree species," said John Seiler, professor of forest biology at Virginia Tech.

The first thing you might notice about the trees on the mountains this year is that they started to change from green to orange and yellow relatively early.

“There are some species, couple weeks they turned early compared to last year," he said. “And that’s mostly due to the cold weather that’s pushed it ahead."

Even with a week left in October, some trees have already shed their leaves for the season.

“Ash trees are done. Most of our hickory trees are done," he said.

But if you want to see some gorgeous oak trees turn colors, you’ve still got time.

“Some of our best reds aren’t here yet," Seiler said. "White oak gets maroon. Scarlet oak, well, turns scarlet. And so they’ll continue on through the rest of the month of October.”

While there are many places known for fall foliage, southwest Virginia can’t be outdone in one particular way.

“We have some of the highest tree diversity in the Appalachians, as well as just about anywhere in North America," Seiler said.

Such variation means the region has lots of colors and a long fall season as each tree transitions at different times depending on the the elevation.

“So New England is great, right?" Seiler said. "But they have sugar maple and northern red oak. Pretty much, that’s what they have and they’re really both nice, but it’s not as long of a season and you don’t get the diversity.”

Further proof is in these two photos of the same tree on Virginia Tech’s campus one year apart.

Green ash tree in front of Cheatham Hall on Virginia Tech's campus looks vastly different from...
Green ash tree in front of Cheatham Hall on Virginia Tech's campus looks vastly different from Oct. 23, 2019 (left) to Oct. 23, 2020 (right).(John Seiler)

Seiler explained the biggest factor in the changing of the leaves every year is the length of day.

“But then cold temperatures can move it up; warm temperatures can delay it," he added. "And then another factor that can change it like what happened last year, we had a really really serious drought.”

So what determines the colors of the trees? Turns out, even when the trees look green, there’s always a yellow pigment in the leaves, but in the fall the green fades.

“The greens breaking down due to the short days," he said. "That’s the chlorophyll and it’s leaving behind the yellow to slightly orange.”

The red pigments form in the fall due to sugar compounds that turn vibrant red in direct sunlight.

“You see this leaf is developing red nicely cause it’s out in the sunshine," Seiler said holding up a leaf stalk. "But if you just put this little leaf out of the way that’s covering it, you see a perfect little crescent of green where it’s been shaded the entire time.”

Forestry expert, John Seiler, demonstrates how some leaves only turn red where the leaves have...
Forestry expert, John Seiler, demonstrates how some leaves only turn red where the leaves have received direct sunlight.(WDBJ7)

Scientists say the red is like a sunscreen for the trees.

“You don’t need sunscreen if you’re in the shade, under the umbrella," he said. "And the trees don’t need the red sunscreen if they’re in the shade. They’re well designed.”

Seiler explained southwest Virginia will likely lose its fall colors in the next 7-10 days. He said driving the Blue Ridge Parkway is one of the best ways to see fall colors because as you go up higher in elevation the types of trees change. You’ll also get to see the differences from either side of the mountains.

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