If we were forced to pick a favorite month for a drive in the Black Hills of South Dakota, we would be very tempted to pick October. The mountain air is crisp and fresh-smelling. The weather is pleasantly cool. And the aspen trees are putting on their annual show.
Aspen can be found throughout the Black Hills. It tends to grow into the area where past forest fires have burned the pines and opened up the soil to sunshine. After a fire, trees such as aspen move in quickly to provide nature’s erosion control until the pine and other species can re-establish themselves.
The aspens tend to take over the high country draws and saddles, providing punctuation between the rocky cliffs and the pine and spruce that flourish in the lower, wetter elevations.
Why the colorful display of deciduous trees each fall? We can thank chlorophyll, or a lack of it, for the visual bounty.
In spring and summer, the chlorophyll-rich cells of the leaves are bright green as the tree is busy converting sunlight into the simple sugars that sustain the trees year-round. As the temps cool, the chlorophyll breaks down, and the green disappears. What’s left, the natural reds, oranges, and yellows are what we see in the fall.