Temperatures are dropping, daylength is decreasing, and there are fewer hours of sunlight each day. These things trigger the trees to begin making changes for the cooler months ahead. These changes affect leaf pigmentation and cause the beautiful fall colors we see in Alabama State Parks and beyond.
There are three pigments produced by leaf cells which are responsible for leaf color: chlorophyll, caroteniod, and anthocyanin. Chlorophyll is what trees use to produce their food from sunlight through a process called photosynthesis. This pigment is present throughout the growing season and is the cause of green coloration in leaves. Caroteniod pigments cause yellow and orange coloration in leaves and many fruits and vegatables. They are responsible for the yellow we see in corn and the orange in carrots. Like chlorophyll, this pigment is also present in all trees throughout the growing season. The third leaf pigment is anthocyanin, and it is responsible for red coloration. Unlike the other two, however, anthocyanins are only produced by some trees under certain conditions, and typically only in autumn.
Trees begin to produce less chlorophyll when daylength is decreasing and the trees receive less sunlight. This causes their photosynthetic rate to slow, and eventually the production of chlorophyll will come to a halt as the trees prepare for the winter months. When the leaf cells no longer have chlorophyll, the carotenoids become visible and the leaves show their yellow, orange, and brown hues. The red coloration caused by the anthocyanin pigment is a little less straight forward in the way it appears. That's because unlike chlorophyll and carotenoids, anthocyanins are not present in all leaves. Researchers believe this red pigment may be a form of protection for some trees because it allows these trees to recover nutrients from leaves when night time temperatures become too cool to do so without anthocyanin. During warm days, leaves produce sugars that they may not be able to transport if the temperatures plunge at night. Because of this, it is believed that string of warm days with very cool nights can intensify red leaf coloration as they need the extra protection from anthocyanins to help with nutrient transport.
As you explore Alabama State Parks during the fall months, see if you can observe which tree species have yellow and golden brown leaves and which ones exhibit reds. You can also check out the Alabama Fall Color Trail and read the al.com article titled, "Best fall foliage in Alabama: 10 places to see autumn colors as leaves change". There's nothing quite like experiencing the beauty of fall color in an Alabama State Park. Every park has beautiful views to experience this fall, so here are a few suggestions to help you start planning. Lake Lurleen is located just miles from Tuscaloosa and features an improved campground with gorgeous lake views. Monte Sano State Park features a beautiful overlook, and the birding opportunities are incredible there! Another breathtaking view is from the Butler's Pass scenic overlook at Lake Guntersville State Park. The highest point in Alabama can be found at Cheaha State Park, and it is second to none when it comes to fall scenery. The list could go on for pages and still not exhaust all of the options, so we at Alabama State Parks sincerely hope you will spend time making beautful memories in the parks this fall.