Biology ETDs


Sarah Dean

Publication Date



Globally, increasing human populations have either caused or accelerated several types of environmental change. Symbiotic microbes have powerful effects on plant fitness, yet little study has been done on how microbial-plant relationships are affected by environmental changes. In two different ecosystems I explore how either nitrogen (N) pollution or drought can alter root associated microbe (RAM)-plant relationships using Next Generation Sequencing. In moist-meadow alpine tundra at Niwot Ridge, CO, I examine the relative contribution of host identity, N enrichment, and plant neighborhood on RAM diversity and community composition in two co-dominant plant species; Geum rossii and Deschampsia cespitosa. In New Mexican piñon-juniper woodlands, I sampled roots from a site in which mass Pinus edulis dieback was simulated to mimic the effects of extreme drought events, which are predicted to become more frequent as climate change progresses. I examine the effect of host and neighbor identity, as well as the effect of dead P. edulis neighbors, on root associated fungi (RAF) of P. edulis and Juniperus monosperma. I also compare RAF communities between piñon-juniper woodlands and more arid juniper savanna, a good proxy for what piñon-juniper woodlands will become should these extreme drought events become more frequent.

Project Sponsors

National Science Foundation, Department of Energy, University of New Mexico Graduate Resource Allocation Committee




microbiology, ecology, molecular ecology, fungi, bacteria, next generation sequencing, microbial ecology, symbiosis, root associated microbes, mycorrhizae

Document Type


Degree Name

Microbial Ecology

Level of Degree


Department Name

UNM Biology Department

First Advisor

Robert, Sinsabaugh

First Committee Member (Chair)

Natvig, Donald

Second Committee Member

Collins, Scott

Third Committee Member

Porras-Alfaro, Andrea