Date of Award


Degree Name

Master of Science




Jennie R. McLaren


Atmospheric warming is occurring due to anthropogenic release of carbon dioxide. Climate change has the potential to increase microbial activity in soil, where a significant amount of terrestrial carbon is stored, which may lead to release of this soil carbon into the atmosphere, positively feeding back to global temperature rise. Understanding how the indirect impacts of climate warming, like shifts in plant community composition, affect soil microbes can improve predictions of ecosystem functions and services under climate change. This project examined direct and indirect consequences of warming on microbial processes using independent and combined treatments of experimental warming and dominant plant species removal along an elevation gradient in the alpine Rocky Mountains, Colorado, throughout the summer growing season. We analyzed multiple soil microbial responses to our treatments including respiration, metabolic functional diversity, microbial biomass carbon and nitrogen, and extracellular enzyme potential activity. There were few direct responses to either warming or removal treatments, and for variables that did respond to either warming or removal, it was typically also in a higher order interaction with another factor. When warming and removal interacted with each other, as they did for microbial biomass carbon and the potential activity of the enzymes β-glucosidase, Cellobiohydrolase, and Phosphodiesterase, it was because there was a negative effect of warming only when the dominant plant species was removed. We also observed that effects of both treatments vary throughout the growing season, and also differ across elevation, with higher elevations seeing stronger effects of warming and removal. Our results emphasize the need to further investigate changing plant community structure as an additional driving force when considering soil microbial responses to warming and predicting carbon dynamics under future global change.




Received from ProQuest

File Size

53 p.

File Format


Rights Holder

Sydne Rose Spinella