Abstract

Decompositional dynamics between soil-dwelling fungi control the degree to which carbon from organic matter is either stored or released, potentially as atmospheric CO2. Two groups (guilds) of fungi — plant root-associated ectomycorrhizae (ECM) and free-living saprotrophs — have been observed to significantly influence net decomposition rates. A decrease in decomposition is typically observed as a result of interguild competition, due in part to differences between guilds in carbon sourcing. As post-fire remediators and pioneer species, fungi are particularly relevant to the study of ecosystem effects of forest fire. The outbreak of forest fires in Western North Carolina in 2016 provided a rich opportunity for research, especially significant considering the projected increase in wildfire with the progression of global climate change. I established plots in an area affected by the Party Rock Fire, with three sets of paired burned/unburned plots containing subplots which were either trenched to disrupt ECM systems or left untrenched. By measuring soil respiration and decomposition of organic matter by mass in these plots over a year, I sought to elucidate the effects of fire upon ecosystem-level decomposition processes, and thus upon interguild fungal interactions. Higher rates of decomposition were predicted in trenched plots than in untrenched, and lower rates in burned plots than in unburned due to shifts in carbon-to-nitrogen ratio. C:N was not significantly altered by the fire, but soil respiration rates were greater in unburned than burned when compared by trenching treatment, and greater with leaf litter than with bare soil, suggesting the competitive suppression of fungal decomposition is limited to the litter layer in this system.

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