Off-campus UMass Amherst users: To download campus access dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users: Please talk to your librarian about requesting this dissertation through interlibrary loan.
Dissertations that have an embargo placed on them will not be available to anyone until the embargo expires.
Open Access Thesis
Molecular & Cellular Biology
Master of Science (M.S.)
Year Degree Awarded
Month Degree Awarded
The year 2020 marked one of the hottest years on record to date, with the average global temperature reaching 1.2 °C above pre-Industrial era (1880) temperatures. Rising temperatures are largely attributed to increasing CO2 levels from the widespread burning of fossil fuels. Terrestrial ecosystems make up the largest global carbon reservoir. In the soil, microorganisms play major roles in carbon and nutrient cycling, decomposition, and mediation of plant health, among several others. Involvement in such important processes makes soil microbial communities incredibly insightful for understanding earth’s changing climate.
The Harvard Forests in Petersham, MA implement belowground heating cables to warm experimental soils 5°C above the ambient soil temperature. With this dramatic temperature difference, researchers intended to simulate a worst-case scenario for earth’s climate. However, upward trends in global warming make this projection not as far out of reach as originally thought.
In 2017, the heating cables in experimental soil plots were turned off after approximately 15 consecutive years of warming and the soil was allowed to re-equilibrate to the ambient temperature. Experimental soils took around 2 months to reach the same temperature as the control soils. Significant changes in soil respiration levels and moisture were observed, raising the question as to whether soil microbial gene expression levels changed as well. Soil samples were collected for bulk RNA extraction from both heated and control soil plots on the day the heating cables were turned off (Day 0) and sequenced on the Illumina NextSeq platform at the Department of Energy’s Joint Genome Institute.
Here I present a metatranscriptomic analysis of the Harvard Forest soil microbiome on Day 0 to uncover the soil microbial community’s transcriptional response to long-term warming. Major phyla that were less transcriptionally active in response to warming include Basidiomycota, Pseudomonadota, Bacteroidetes, and Acidobacteria, which have essential roles in decomposition, nutrient cycling, mediating plant health, and more. Phyla that were more transcriptionally active in response to warming include Actinobacteria, Ascomycota, and Chloroflexota, which participate in biogeochemical cycling, polymer breakdown, antimicrobial activity, and more. These changes in activity reflect the ways in which the soil microbiome responds to chronic warming.
Linnehan, Brooke A., "A Metatranscriptomic Analysis of the Long-Term Effects of Warming on the Harvard Forest Soil Microbiome" (2022). Masters Theses. 1249.