The Microbial Ecology of Biological Soil Crusts Within a Temperate Coastal Dune Ecosystem

Biological soil crusts (or biocrusts) are a consortium of phototrophic microorganisms, bacteria, fungi, lichens and mosses, each embedded within a self-aggregated soil matrix found among the first few millimeters of the soil surface. Referred to as the “living skin” of the Earth, biocrusts are known for their ecological contributions to dryland biogeochemical cycling, soil stability, and their influence on soil water dynamics. They colonize a significant proportion of arid and semi-arid ecosystems and our understanding of the global relevance of biocrusts has increased exponentially over the last few decades. However, biocrusts are not limited to only dryland ecosystems, with recent research showing biocrust to be present throughout a variety of temperate ecosystems that host nutrient-poor, excessively drained soils with limited vascular plant establishment. Though it’s suspected that temperate biocrusts share many of the same ecological functions as their dryland counterparts, our current knowledge on the ecology of biocrusts within temperate biomes is limited, resulting in their absence in consideration from ongoing land management efforts. With the combination of field data collection, genomics, and the implementation of robust computational analyses, my thesis work explores the spatial and microbial ecology of biocrusts within a US federally-preserved temperate coastal dune ecosystem. For my first chapter, I conducted a field study to survey biocrusts within the Miller Woods dune complex, located within the Indiana Dunes National Park. My objective was to understand how biocrusts were distributed among a complex dune system and how their distribution was related to differences in dune morphology and their surrounding above-ground community. For my second chapter, I collected samples of biocrusts, their adjacent sub-surface soil, and non-crusted soils throughout Miller Woods to understand the influence biocrusts have on the surface and underlying soil microbiome. Overall, my thesis work introduces biocrusts as important members of coastal dune ecosystems found along the southern shore of Lake Michigan.