Date of Award
This project was part of a larger experiment conducted by Amber Horning and Jason Hoeksema in the Department of Biology at the University of Mississippi, which was set up to investigate variation (over time, and with different light levels) in resource exchange between pine seedlings and two different species of ectomycorrhizal (EM) fungi. The experiment was conducted in a growth chamber, with mycorrhizal pine seedlings growing in plexiglass "mycocosms." I worked with two EM fungal species (Rhizopogon roseolus and Pisolithus arhizus, hereafter "Rhizopogon" and "Pisolithus"), which were collected locally near Oxford, Mississippi under loblolly pine. I selected a subset of replicates from the main experiment, three each for each combination of fungal species and light level (high and low). These twelve mycocosms were examined at 5 time points over a 24-hour period (0100, 0500, 0900, 1400, and 2000) in November 2017 and February 2018. I found that carbon efflux rates varied throughout the 24-hour period and increased during the night in the November measurements. I also found that the amount of light exposed to the mycocosm altered the respiration rates, with the low-light treatment primarily having higher carbon dioxide efflux than the high-light treatment, particularly in the November measurements. I also found that carbon dioxide efflux rates of the plant-side of the mycocosm differed based on which mycorrhizal fungi was associated with the P. taeda. I concluded that it is not ideal to extrapolate soil respiration rates taken at one time point throughout an entire 24 hours.
Easterling, Richard, "Diurnal Variation in CO2 Efflux by Pine Seedlings and Root-Associated Mycorrhizal Fungi" (2019). Honors Theses. 990.