Environmental Studies Program



Abigail Ridder

Date of this Version



Environmental Studies Undergraduate Student Thesis, University of Nebraska-Lincoln, 2022


Copyright 2022, Abigail Ridder


Boundary forests are found growing interdigitated with grasslands across the Great Plains. The Niobrara River valley boundary forest has a unique composition of species not seen anywhere else in North America. Encroachment of eastern redcedar (Juniperus virginiana L.) into grasslands and forests is significantly increasing eastern redcedar’s presence in the Niobrara River Valley as well as in the rest of the Great Plains region. This tree species is capable of significantly decreasing recruitment and diversity in grasslands, which can change the composition of the entire ecosystem. However, the effect of eastern redcedar on recruitment and diversity of naturally forested ecosystems is not as well understood. We conducted a forest inventory and seedling census in the Niobrara River valley to investigate how eastern redcedar is impacting the density and diversity of both the understory and overstory woody community in this unique forest. Using quantile regression, we found that eastern redcedar basal area had a significant negative effect on woody understory and overstory density, diversity, and richness in all cases. These results indicate that the Niobrara valley boundary forest is heading toward a future with decreased diversity and density of woody species, and corresponding reductions in the provisioning of ecosystem services, if eastern redcedar increases its presence in this ecosystem.