A Senior Capstone Experience by Sharon Niedringhaus ’23

Submitted to the Department of Environmental Science and Studies

Advised by Dr. Rebecca Fox

Contributor Biography: Sharon Niedringhaus graduated summa cum laude from Washington College in May 2023 with a Bachelor of Science in Environmental Science and minors in Biology and Chesapeake Regional Studies. Her SCE won the Holstein Student Thesis Prize for ethics. Sharon is originally from Frederick, MD and is currently working at USFWS Patuxent Research Refuge in Laurel, MD as a Chesapeake Conservation & Climate Corps Member.

Description: The American chestnut (Castanea dentata) was once widespread throughout forest ecosystems in the Eastern U.S. as a dominant canopy tree. As a foundation tree species, it was an important producer of food for other forest species and was important to humans for lumber and chestnuts. The chestnut blight (Cryphonectria parasitica) was introduced to the U.S. in 1904 by imported Asian chestnuts and destroyed American chestnut populations. American chestnuts became functionally extinct due to mature trees being killed by the blight and any new sprouts being infected and killed by the blight before they reached maturity to produce nuts and reproduce. Research focused on restoration of the American chestnut has been ongoing for years, but it is important to determine whether this restoration is feasible and necessary. The three main methods for restoration are: backcross breeding, bioengineering, and biocontrol. Backcross breeding confers resistance to chestnut trees by crossing American chestnuts that are not resistant to the blight with Asian species that are. Bioengineering involves inserting a gene from wheat into the American chestnut’s genome that will decrease the effects of the blight on them. Biocontrol involves injecting cankers caused by the blight on infected trees with a virus that will decrease the impact of the blight on the trees. In addition to threats by the blight, climate change and another disease called Phytophthora root rot could impact American chestnut populations and should be considered. Based on the current body of research, American chestnut restoration is feasible and necessary and could set a precedent for restoration of other threatened tree species in the future.

Read Sharon’s SCE below: