Date of Award

Fall 2024

Project Type

Thesis

Program or Major

Microbiology

Degree Name

Master of Science

First Advisor

Serita D Frey

Second Advisor

Louis S Tisa

Third Advisor

Jessica Ernakovich

Abstract

Nitrogen (N) is an essential nutrient in terrestrial ecosystems and the transformations it undergoes mediated by microbes in soil are central to N cycling. While rates of atmospheric N deposition due to anthropogenic activity increased dramatically with the industrial revolution, government regulations in the late 20th century resulted in a reversal. Rates of atmospheric N deposition remain well above pre-industrial levels, but the last two decades have seen a steady decrease in areas such as the Northeastern United States. To investigate the potential for soil recovery from long-term N addition, we measured a suite of soil biogeochemical properties in a northeastern temperate forest which experienced 31 years of simulated N deposition before treatment cessation in 2019. Four years after the cessation of treatment, fungal communities remained significantly altered from those in soil receiving only ambient N deposition. Accumulated soil carbon (C) and N stocks persisted, while manganese (Mn) concentrations remained significantly reduced. Soil pH increased after treatment cessation but was still significantly more acidic in comparison to soil in control conditions. Persistent soil C, low Mn concentrations, and soil acidity suggest that the effects of N enrichment remain strong in forest soil after several years after N enrichment treatments ended.

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