Differences in soil fungal assemblages associated with native and non-native tree species of varying weediness

Abstract

Here we characterize and compare the diversity of belowground fungal communities of maples (Sapindaceae: Acer) varying in both nativity and weediness, and interpret our findings in the context of multiple non-exclusive theories on tree invasions and fungal associations. We made our fungal community comparisons based on high-throughput Illumina sequencing of the internal transcribed spacer region of fungal ribosomal DNA of soil samples associated with the roots of different species of maple collected from six sites throughout Central Pennsylvania. In our system, we found that weedy species, regardless of nativity, had the greatest soil fungal richness and that the nonnative invasive Norway maple had the highest abundance of mycorrhizal mutualists. Despite that much of the fungal community variability in our system was attributable to inter-site variability, we found that the core fungal communities associated with nonnative tree species were an inclusively larger set that included nearly all of those associated with native trees in addition to many not found with the natives, and the core communities of non-weedy species were largely a subset of those associated with weedy maples. In addition to confirming the strong influence that site variation has on soil fungal communities, our findings are also largely consistent with positive feedback from native fungal communities, possible co-invasion by fungal associates that are only associated with the nonnative trees, and generally add to the growing number of studies that have observed a greater abundance of mutualists associated with invasive trees that interact with arbuscular mycorrhizal fungi.