Backcountry Science: Leaf Peepin’

Fall is here. College football is underway. Local grocery stores are already jam-packed with Halloween gear. You’re starting to hear about pumpkin spice EVERYTHING. And…leaf season is coming.

We all know that the Appalachians are famous for our fall color, but you probably didn’t know that we have one of the most vibrant and prolonged autumn color seasons in the world. We’ll get to why in a minute, but let’s first dive deeper into the science of fall color with this iteration of our Backcountry Science series.

Why Do Leaves Change Color in the Fall?

Believe it or not, the process of leaf color change in the fall months can be an incredibly complex process – a result of the biology of the trees themselves, the regular changing of Earth’s seasons, and local weather conditions. This excellent video from Virginia Tech below breaks down the details:

…but that’s not all, though! Many of our Appalachian plants – from hemlocks to pines to rhododendron and laurel – are evergreens, meaning that they don’t lose their leaves (yes, needles are leaves!) at all throughout the year. Many of these plants have unique processes to make their tissues last through winter, including the concentration of antifreeze-like compounds and tightly curling their leaves to limit damage from cold temperatures.

Still other plants, like our local beech trees, undergo a process called marcescence. In these species, leaves change color but don’t drop off like we see with other trees. These trees retain their dead leaves on the plant through winter (or until wind or other forces physically break them off) as a strategy that possibly helps with survival over the winter months. During winter hikes in our region, in fact, you may notice the dead leaves of beech trees and some oaks rattling in the wind.

The Special Fall Color Season of the Appalachians

We mentioned earlier that the southern mountains have one of the longest and best fall color seasons of anywhere on Earth. But why? The answer lies in a couple of factors. First, there is simply an astounding amount of plant diversity here in the Appalachians, and more types of trees means more types of colors that paint our autumn forests. (Get a feel for the detailed science behind what trees change into which colors – and why – here.) Our mountains’ tree diversity is so astounding that it can be possible to have as many or more species of trees occurring together on a single mountain in our region than can be found in some entire European countries. That helps to create a simply amazing tapestry of colors on our mountain slopes.

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Reds, yellows, and oranges explode in a diverse hardwood forest on North Carolina’s Grandfather Mountain. Note the lack of color at higher elevations, which saw a change occur earlier in the season.

The other reason our leaf season is special, though, has to do with our mountains’ elevation. Higher elevations typically mean cooler and wetter climates – climates that mimic conditions found much farther to our north. In fact, driving up a few thousand feet in elevation from somewhere like Abindgon, VA or Bristol, VA to Whitetop or Mount Rogers (both well exceeding 5,000 feet above sea level) is the climatological and ecological equivalent of driving some 1,000 miles north to Quebec.

How does this relate to fall leaf color? Leaves tend to change earlier in areas where cooler conditions prevail – or where “fall starts earlier” – meaning that color begins to change in most spots in the mountains a few weeks earlier on higher summits than it does in our lowest valleys. This means that you can start to find color in late September atop our highest peaks above 5,000 and 6,000 feet, with color lasting all the way into November in our deeper river valleys. It’s this trait – coupled with the astounding amount of tree diversity our region has, as mentioned above – that makes our leaf season so prolonged and beautiful.

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Leaves ablaze with fall color at 3,000 feet above sea level atop Norton, Virginia’s Flag Rock…while colors are just appearing some 1,000 vertical feet lower in downtown.

Planning Your Hikes and Drives Around Fall Color

Want to get outside this fall and maximize your chances of seeing the best colors our mountains have to offer? You can use the science of autumn to your advantage to make the most of our seasonal changes. Head for our highest elevations in late September to see the region’s first peeks of fall color. Places well above 5,000 feet like Roan Mountain or Mount Rogers/Grayson Highlands are always sure bets – the higher, the better. If you don’t want to hike, driving North Carolina’s portion of the Blue Ridge Parkway gives an excellent (albeit crowded) opportunity to see early-season color in action.

As we move into October, watch for color appearing on distant hillsides and aim for destinations that are at or above 4,000 feet. Places like southwest Virginia’s High Knob give an excellent way to view distant color. Check out High Knob’s Chief Benge Trail or trails at Flag Rock Recreation Area to get into the woods, or see the High Knob Region’s tourism website for more in-depth trip planning. Head down in late October and November to catch the last phase of color change at our lower elevations. Bike rides or hikes on the New River and Tweetsie trails are good options for getting outside at lower elevations during this time period.

The best rule of all, however, is to keep your eyes peeled once fall color season starts. The vibrancy of colors (or lack thereof) each year can be determined by variable weather conditions leading up to and during the seasonal changeover, so being aware of where the leaves are changing and why will help ensure that you have the best fall outdoor season possible. Sites like Appalachian State University’s Fall Color Report are wonderful resources to use to get a feel for regional color conditions as they happen.

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