Soil Microbial Community Responses to Changing Environments

Soil microbial communities are an essential component of Earth’s ecosphere. They regulate carbon and nutrient cycling and interact closely with plants via root/rhizosphere interactions, ultimately influencing the environment on a global scale. The composition of microbial communities is determined by direct and indirect interactions with both biotic and abiotic environmental factors and can influence ecosystem processes (e.g. plant productivity, gas exchange) through taxa-specific functional capacities. Using genomic sequencing, field measurements, and soil chemical characterization, my research focuses on untangling the interactions that determine microbial community structure and exploring subsequent effects on the genetic capacity for organic matter decomposition, nutrient cycling, and metabolic activity. My dissertation examines soil microbial dynamics from two ecosystems undergoing vegetation shifts; 1) a temperate deciduous forest impacted by an invasive pest, and 2) the moist acidic tundra of Northern Alaska. My results suggest that ecosystem-specific limiting factors to microbial growth likely contribute to determining microbial community structure and genetic functional capacity. By providing a holistic conceptual context, I hope to demonstrate the importance of understanding soil microbial relations to the environment in order to fully comprehend ecosystem scale processes.