DOI: 10.5061/dryad.rfj6q57qj
title: Data from: Mycorrhizal identity and light shape tree seedling biomass responses in plant–soil feedbacks

description: Plant–soil feedbacks (PSFs) are key drivers of forest composition and
 diversity, yet their direction and magnitude may depend on the mycorrhizal
 identity of interacting species, environmental conditions, and
 experimental context. We conducted complementary greenhouse and field
 experiments using Acer rubrum L., Acer saccharum Marsh., Prunus serotina
 Ehrh. (all arbuscular mycorrhizal [AM] species), and Quercus alba L., and
 Quercus rubra L. (all ectomycorrhizal [EM] species) to test how
 biomass-based PSFs vary with mycorrhizal matching between seedlings and
 adult trees, light availability, and soil microbial communities. Seedlings
 were grown in soil conditioned by conspecifics, conmycorrhizal
 heterospecifics, or heteromycorrhizal heterospecifics under controlled and
 natural light regimes. Consistent with expectations, AM species
 consistently exhibited negative PSFs under low light, and EM species
 tended to show more positive PSFs, but this pattern was contingent on
 light and greenhouse versus field setting. For AM species, negative PSFs
 occurred primarily under low light and were neutralized or reversed under
 higher light. EM species showed generally more positive PSFs across light
 levels and settings, although species-specific differences emerged. PSFs
 were driven largely by conspecific soil conditioning, with limited
 influence from the mycorrhizal identity of heterospecific neighbors.
 Results from greenhouse versus field settings diverged, with field PSFs
 sometimes attenuated or reversed, particularly for Q. alba. These findings
 highlight that biomass-based PSFs are not fixed species traits but
 context-dependent outcomes influenced by mycorrhizal type, light
 availability, and environmental setting. Incorporating these factors is
 essential for predicting how PSFs influence seedling recruitment, forest
 dynamics, and biodiversity.
description: # Data from: Mycorrhizal identity and light shape tree seedling biomass
 responses in plant–soil feedbacks Dataset DOI:
 [10.5061/dryad.rfj6q57qj](https://doi.org/10.5061/dryad.rfj6q57qj) ##
 Description of the data and file structure **Experimental Design and Data
 Collection** We conducted complementary greenhouse and field transplant
 experiments to test how plant–soil feedbacks (PSFs) vary with mycorrhizal
 identity, soil source, sterilization of conspecific soils, and light
 availability. Five temperate tree species differing in mycorrhizal
 association (*Acer rubrum*, *Acer saccharum*, *Prunus serotina*, *Quercus
 alba*, *Quercus rubra*) were used in the greenhouse experiment. Two EM
 species (*Q. alba*, *Q. rubra*) were used in the field experiment. Soils
 were collected from mapped adult trees in a mixed hardwood forest and used
 either live (non-sterile) or sterilized to isolate biotic versus abiotic
 soil components. **Greenhouse Experiment** The greenhouse experiment was
 conducted at Michigan State University’s Tree Research Center (East
 Lansing, Michigan, USA; 42.7°N, 84.5°W). Three light environments (~2%,
 ~15%, and ~30% full sunlight) were created using shade cloth and
 reflective material. Seedlings were grown in soil sourced from conspecific
 and heterospecific adults spanning both AMF- and EMF-associated species. A
 subset of conspecific soils was gamma-sterilized to remove soil biota
 without substantially altering soil chemistry or physical structure. Pots
 containing a 1:1 mix of field soil and potting substrate were arranged
 across nine greenhouse benches, with three benches per light level. Each
 species × soil source × light combination had 30 replicates, for a total
 of 3,150 seedlings. Seedlings grew for 12 weeks, after which whole-plant
 dry biomass (mg) was recorded. **Field Transplant Experiment** The field
 experiment was conducted at Alma College’s Ecological Field Station
 (Vestaburg, Michigan, USA; 43.4°N, 84.9°W) using *Q. alba* and *Q. rubra*
 seedlings. Intact soil cores (46 cm depth) were collected under mapped
 adult trees in 2016 and 2017 and transplanted into 18 field plots arranged
 across a canopy light gradient. Plots were subdivided into five subplots
 (A–E). Seedlings were planted into cores and grown for two full growing
 seasons. Canopy light was quantified for each subplot using hemispherical
 photographs to derive Indirect Site Factor (ISF). ISF values were grouped
 into categorical low, medium, and high light classes. Soils included
 conspecific and heterospecific live cores, and sterilized conspecific
 cores. Two EM species (*Q. alba*, *Q. rubra*) were grown across all soil
 types; seedling whole-plant dry biomass (mg) was recorded at the end of
 the experiment. ### Files and variables #### File: GH_Data.csv
 **Description:** Greenhouse Experiment ##### Variables * **Number**:
 Unique seedling identifier * **Species**: Seedling species * ACRA = *Acer
 rubrum* * ACSA = *Acer saccharum* * PRSE = *Prunus serotina* * QUAL =
 *Quercus alba* * QURU = *Quercus rubra* * **Soil:** Soil source (adult
 species) * ACRA = *Acer rubrum* * ACSA = *Acer saccharum* * PRSE = *Prunus
 serotina* * POGR = *Populus grandidentata* * QUAL = *Quercus alba* * QURU
 = *Quercus rubra* * CON-ST = sterile conspecific * **Light:** Light
 treatment * Low (~2% full sunlight) * Med (~15% full sunlight) * High
 (~30% full sunlight) * **SpMyco:** Seedling mycorrhizal type * AMF or EMF
 * **Conspecific:** Seedling–soil identity * CON (conspecific live) *
 CON-ST (conspecific sterile) * HET (heterospecific live) * **SoilMyco:**
 Mycorrhizal type of soil source adult * AMF, EMF, or Sterile * **Adult:**
 Unique identifier for adult tree soil source * **Bench:** Greenhouse bench
 * **Biomass:** Final whole-plant dry mass (mg) #### File: Field_Data.csv
 **Description:** Field transplant experiment ##### Variables * **No**:
 Unique seedling identifier * **Plot**: Field plot (1–18) * **Subplot**:
 Subplot (A–E) * **Species**: Seedling species * QUAL = *Quercus alba* *
 QURU = *Quercus rubra* * **Light_ISF**: Numeric Indirect Site Factor value
 from hemispherical photography * **Light**: Light class (Low, Med, High)
 based on ISF * **Core**: Year soil core was collected (2016 or 2017) *
 **Soil**: Soil source (adult species) * ACRA = *Acer rubrum* * ACSA =
 *Acer saccharum* * PRSE = *Prunus serotina* * POGR = *Populus
 grandidentata* * QUAL = *Quercus alba* * QURU = *Quercus rubra* * CON-ST =
 sterile conspecific * **Adult:** Unique identifier for soil-source adult
 tree * **Conspecific**: Seedling–soil identity * CON (conspecific live) *
 CON-ST (conspecific sterile) * HET (heterospecific live) * **Myco**:
 Seedling mycorrhizal type * EMF for all entries * **SoilMyco**:
 Mycorrhizal type of soil source adult * EMF, AMF, or Sterile **Biomass**:
 Final whole-plant dry mass (mg) ## Code/software All analyses were
 conducted in R (v.3.5.1). Linear mixed-effects models were fit using lme4;
 significance and pairwise tests were obtained using car and emmeans.
 Biomass-based PSFs were quantified using log-response ratios with
 nonparametric bootstrapping. ## Access information For questions related
 to data, methodology, or availability: **Dr. Sarah McCarthy-Neumann**\
 Email: [sneumann@tnstate.edu](mailto:sneumann@tnstate.edu)