Jan 04th, 2022

Biology Faculty at HPU Publish a New Perspective on Autumn Leaf Color

Drs. Niky Hughes and Christian George, biology faculty at High Point University, recently published a new perspective on autumn leaf color. The paper was coauthored by HPU biology student Corinne Gumpman and Dr. Howard S. Neufeld, professor of biology at Appalachian State University.

The article, “Coevolution and photoprotection as complementary hypotheses for autumn leaf reddening: a nutrient-centered perspective,” was written in response to an ongoing debate between plant biologists in the journal New Phytologist, concerning the function of red anthocyanin pigments in leaves during fall. Some authors argue that red colors in autumn function as sunscreen or antioxidants to protect translocation of nutrients out of leaves for winter, while others are equally convinced that red colors evolved to signal poor host quality to insects who lay their eggs in trees during the fall.

Hughes and colleagues argued that these two explanations are not mutually exclusive, and may even complement one another, if only looked at from a different angle. Rather than focusing on sunlight and low temperature as the main drivers of autumn leaf colors like previous authors, they instead looked to the soil.

“One critical piece of the puzzle that had been overlooked is that nitrogen deficiency is known to result in redder autumn leaves in species like sugar maple”, Hughes explains. “This is critical, because trees with low nitrogen are both less nutritious for insects AND in greater need of photoprotection. So from our perspective, anthocyanins could be simultaneously functioning in both roles simultaneously. Both functions make sense.” says Hughes.

Their focus on soil nutrients could also help explain larger geographic trends in leaf reddening. Eastern North America is known to have a greater abundance of red-leafed species in autumn than Europe, which previous authors had attributed to brighter conditions and more dramatic temperature fluctuations in autumn. For their study, Dr. Christian George used GIS to characterize soil fertility in forests of the two continents, and showed that soils of Eastern North American forests are also more deficient in nutrients like nitrogen and phosphorus compared to European forests. This suggests that there may be more factors at play than simply light and temperature, as soil quality could also explain the existing trend.

Gumpman, who is double majoring in biology and english, has written articles for the Campus Chronicle on the topic of fall color change. She hopes to pursue a career in scientific journalism. “This research effort provided me the opportunity to work collaboratively with professors whom I admire. I have learned how demanding yet rewarding research is, and I think that undergraduate research provides students with the experience that they need before entering a more intense program or occupation,” says Gumpman.