Every fall season leaves change color. The fall foliage includes a beautiful mixture of red, yellow and orange leaves. Clint Springer, PhD, associate professor and director of the Institute for Environmental Stewardship and director of the Barnes Arboretum at Saint Joseph's University, is available to discuss the science behind the color changes.
The following quotes by Springer are available for pick-up:
“Autumn leaf color change, technically called senescence, is a process that has evolved in plants to recover nutrients from the plant’s leaves. The drastic change in color occurs because chlorophyll, the primary pigment that drives photosynthesis and shows up green, is degraded to recover the nutrients locked in it. What we see as a result are what are known as secondary pigments that work to protect the plant from excessive solar radiation throughout the growing season. These pigments appear red, orange or yellow because of their light absorbing properties.”
“Trees in the temperate deciduous forest primarily use day length and temperature as cues for when to begin the process. However, seasonal drought leading up to autumn can also affect the timing.”
“Human induced climate change is altering the timing of the event in various degrees based on species because of warmer temperatures and more severe drought throughout the growing season.”