A common ericoid shrub modulates the diversity and structure of fungal communities across an arbuscular to ectomycorrhizal tree dominance gradient

Differences between arbuscular (AM) and ectomycorrhizal (EcM) trees strongly influence forest ecosystem processes, in part through their impact on saprotrophic fungal communities. Ericoid mycorrhizal (ErM) shrubs likely also impact saprotrophic communities given that they can shape nutrient cycling by slowing decomposition rates and intensifying nitrogen limitation. We investigated the depth distributions of saprotrophic and EcM fungal communities in paired subplots with and without a common understory ErM shrub, mountain laurel (Kalmia latifolia L.), across an AM to EcM tree dominance gradient in a temperate forest by analyzing soils from the organic, upper mineral (0–10 cm), and lower mineral (cumulative depth of 30 cm) horizons. The presence of K. latifolia was strongly associated with the taxonomic and functional composition of saprotrophic and EcM communities. Saprotrophic richness was consistently lower in the Oa horizon when this ErM shrub species was present. However, in AM tree..., We carried out this study in the northeastern United States at Yale-Myers Forest (41°57’ N, 72°07’ W), which is characterized as temperate deciduous forest with a mean annual precipitation of 133 cm, a mean January temperature of -4.6°C, and mean July temperature of 21.7°C. The three forest stands used in this study are situated on glacial origin inceptisols from the Nipmuck-Brookfield complex and Woodbridge series, which consist of generally fine sandy loam soils (National Resources Conservation Service [NRCS], 2023). Elevations within sites ranged from 180-290 m and the mean plot slope was 9 degrees (range 0.5-26; CT ECO, 2016). The mean organic soil pH was 4.28 (range 3.16 -5.34) and mean mineral soil was 4.43 (range 2.78-5.48). Overall, the forest understory at our study site had a patchy distribution of the ErM shrub *K. latifolia*, which is the most abundant understory plant species at the forest and accounts for about one-third of all understory vegetation cover (Ward et al. 2021..., , # Data from: A common ericoid shrub modulates the diversity and structure of fungal communities across an arbuscular to ectomycorrhizal tree dominance gradient

[https://doi.org/10.5061/dryad.76hdr7t2c](https://doi.org/10.5061/dryad.76hdr7t2c)

Includes dataset: ErM_dataDryad.csv

Metadata file with variable (column) descriptions: ErM_dataDryad_metadata.csv

NA values in data are missing values.