The impact of nutrient availability, substrate characteristics, and environmental conditions on wood decay and microbial decomposer communities

Wood is an important store of carbon and nutrients globally, and understanding the decay of that wood is critical for estimating rates of global nutrient and carbon cycling. Nutrient availability is important for driving decay rates as decomposers need nutrients to produce wood decay enzymes. My dissertation first explores the differences between bark and wood in nutrient concentrations. Then, by combining environmental and wood substrate manipulations with next-generation sequencing of fungal and bacterial communities, my dissertation explores the relative importance of, and potential interactions among, substrate characteristics, decomposer communities, and environmental conditions. In the second chapter, I explore how bark nutrient concentrations vary across soil fertilities and tree species to understand the amount of and variability in bark nutrients. I found that bark nutrient concentrations and the nutrients in bark differed between soil fertilities and that bark held an estimated 20% of N, P, K, and Mg. In the third chapter, I explore environmental impacts on wood decay by comparing wood in freshwater streams and adjacent terrestrial habitats. Despite finding differences in fungal community composition between habitats, I found wood mass loss was faster in streams than on land because of physical fragmentation and leaching, not differences in microbial decay. In chapter four, I examine how bark impacts wood decay and fungal and bacterial communities. I show that bark and wood differ in decay rate and that bark slows the mass loss of underlying wood. Bacterial and fungal community composition differed between bark and wood, but differences were small. In the last chapter, I compared the effect of substrate and soil nutrient concentrations on wood decomposition and enzyme production. I found that both substrate and soil nutrients influence wood decay and that multiple nutrients impact decay rates.LimitedAuthor requested closed access (OA after 2yrs) in Vireo ETD syste