Life After Death: Investigating the Resistance and Recovery of Fungal Communities to Foundation Tree Mortality

Tree mortality can have cascading effects on the composition and resilience of interacting fungal communities. Yet, little is known about the impact tree mortality, distinct from abiotic drivers (i.e., drought), has on these communities. This dissertation focuses on the resilience of fungal communities to experimental tree mortality in a piñon-juniper woodland. In chapter one, I found that piñon mortality reduced piñon fine root biomass and piñon mycorrhizal fungal diversity, whereas juniper mycorrhizal fungi were unaffected by juniper mortality. In chapter two, I revealed that piñon mortality altered the composition and spatial structure of mycorrhizal and saprotrophic fungi in the soil, but juniper mortality had minimal effect. In chapter three, I discovered that tree mortality, abiotic factors and individual mycorrhizal fungi had positive effects on seedlings. Across all chapters, piñon and associated mycorrhizal fungi were almost always negatively impacted by tree mortality, whereas juniper, and their mycorrhizal fungi, were either unaffected, or benefited.