Although it varies a little from year to year, Douglas County residents should expect to see trees, shrubs and other plants at the height of fall color over the next few weeks. Sumac and poison ivy, which display some of the most brilliant reds that we will see, are already changing.
I frequently get asked just how long the show will last or how good of a one to expect. Leaf color development is completely dependent upon the weather .
We do know that the days are getting shorter and nights are getting cooler, and those two things are a big part of color development.
Short days and cool nights lead to the breakdown of chlorophyll in plant leaves and stems. Chlorophyll is the green pigment that aids in photosynthesis, and it breaks down in the fall because plants know it is unnecessary for the winter.
When chlorophyll breaks down, yellow pigments that are also present in leaf and stem tissue are left behind. Cottonwood, the state tree of Kansas and a common species in the Kansas River Valley, is an example of a tree that appears brilliant yellow once the green pigments have disappeared from the leaves in fall. White ash is another species that often stands out in a tree line when the green fades away, although there are some cultivated varieties with red or purple fall color instead of the standard bright yellow.
Shades of red and purple that appear in the maples, oaks, sweetgums and previously mentioned species develop in the leaves rather than being left behind like the yellow pigments. The colors are the result of sugars, made through photosynthesis, that get trapped in the leaves before they can be transported to the roots for storage. The sugars then go through a chemical change to become red and purple anthocyanins.
Bright, sunny days and cool nights create the best color show. Moisture throughout the growing season can also affect the development of fall color and how long trees hold on to their leaves, but moisture is unlikely to be a major influence this year.
An early freeze or windy days can also shorten the duration of the color show.
If you can, take a walk through one of the city parks in the next few weeks, or drive to one of the nearby state parks. Although maples often get the most credit for their color, I think you will enjoy the hues our native species have to offer. Even the grasses are putting on a show.