Datafiles and R script for analyses and figures for submitted manuscript titled: Loss of dominant tree-mycorrhizal mutualism increases soil fungal diversity and alters community structure

Data used to write the manuscript: Loss of dominant tree-mycorrhizal mutualism increases soil fungal diversity and alters community structureAuthors: Lindsay A. McCulloch^1,2,3*, Carina Berlingeri^1,2, NikhilChari^1,2, Lauren Church^1,2, Cecilia M. Prada^1,2, William Schuster⁴, Katherine P. Terlizzi⁴, Benton N. Taylor^1,2Submitted abstract: 1. Due to their mutualistic partnership with trees, mycorrhizal fungi often make up important components of soil mmicrobial communities. Mortality of tree hosts can have dramatic effects on mycorrhizal populations, but how these shifts impact the remaining soil microbial community and ecosystem function remains poorly understood.2. Using a longterm oak girdling experiment at Black Rock Forest in New York, USA, we looked for patterns in shifting fungal community composition over 10 years following simulated large-scale oak mortality to understand the interactions between canopy tree composition, soil fungal diversity, and forest function. We collected soil samples in treatment plots of 100% oak girdling (OG₁₀₀), 50% oak girdling (OG₅₀), non-oak girdling (N), and a control without girdling (C). We sequenced the fungal community using the ITS1-F and ITS2 reverse primers and classified the communities using the UNITE fungal reference and FUNguild databases.3. Fungal alpha diversity was significantly greater in the OG₁₀₀ and OG₅₀ compared to the control, largely driven by decreased ECM abundance and increased saprophytic fungal abundance in OG₁₀₀ and OG₅₀. ECM fungi showed a strong negative correlation with Archaeorhizomyetes suggesting that this fungal taxa replaced ECM following the loss of oak trees. Girdling treatments, soil nitrogen levels, carbon:nitrogen ratios and soil pH all significantly correlated with fungal community composition.4. The shift from ECM to saprophytic fungi following disturbance can have significant impacts on ecosystem functions and properties such as decomposition, soil respiration, biodiversity and nutrient cycling. The varition in pH among treatments, likely driven by tannic acid in oak leaves, and the effect of pH on fungal diversity highlight the complex feedbacks and co-determined successional dynamics of the tree and fungal communities.5. Synthesis: Here we show that the removal of a dominant plant species, such as oaks in the northeastern US, can have casacading effects on the soil microbial community composition. These shifts in microbial composition may affect ecosystem-level processes such as nutrient cycling. Together, this work improves our understanding of these forests vulnerability to pathogen pressure and the impact these disturbances have not just on the focal species but the ecosystem as a whole.