DOI: 10.5061/dryad.wwpzgmt0c
title: Date from: Mycorrhizal identity of neighboring trees shapes seedling survival and plant-soil feedbacks through trait and light interactions

description: Plant-soil feedbacks (PSF) play a central role in determining forest
 community dynamics, with trees associated with arbuscular mycorrhizal
 fungi (AMF) often experiencing negative PSFs, while those associated with
 ectomycorrhizal fungi (EMF) experiencing positive PSFs. PSFs are driven by
 the difference between seedling performance in both con- and hetero-
 specific soil, and thus the mycorrhizal match or mismatch of the
 heterospecific soil to the focal seedling could drive PSFs. Furthermore,
 functional traits and light environments could influence seedling
 responses. To understand how mycorrhizal type and seedling functional
 traits influence PSFs, we conducted a greenhouse experiment with five
 temperate tree species (three AM, two EM) in soils from six adult tree
 species (three AM, three EM). Seedlings were grown for 12 weeks under
 three light levels. Mycorrhizal colonization and defense/recovery traits
 (phenolics, lignin, nonstructural carbohydrates) were assessed at three
 weeks, and survival was measured over 12 weeks. AM seedlings generally
 experienced negative PSFs, with lower survival in AM-cultured soils, while
 EM seedlings had positive PSFs and higher survival in EM soils. However,
 negative PSFs in AM trees and positive PSFs in EM trees occurred
 only when the heterospecific tree culturing the soil had a
 mismatched mycorrhizal type relative to the focal seedling. PSFs occurred
 under all light levels, but their magnitude was strongest at low light,
 where AM seedlings showed the most negative PSFs and EM seedlings the most
 positive. Mycorrhizal colonization and functional trait values increased
 under high light and were often elevated in conspecific soils (with the
 exception of non-structural carbohydrates). These enhancements in traits
 tended to neutralize PSFs in both AM and EM seedlings. Mycorrhizal type
 match/mismatches between adults and seedlings influenced seedling
 survivorship and PSFs, likely shaping seedling recruitment patterns, and
 long-term forest composition, diversity, and resilience.
description: # Date from: Mycorrhizal identity of neighboring trees shapes seedling
 survival and plant-soil feedbacks through trait and light interactions
 Dataset DOI:
 [10.5061/dryad.wwpzgmt0c](https://doi.org/10.5061/dryad.wwpzgmt0c) ##
 Description of the data and file structure **Experimental Design and Data
 Collection** This study used a controlled greenhouse experiment to test
 how plant–soil feedbacks (PSFs) influence **seedling survival** as a
 function of mycorrhizal identity, soil source, functional trait variation,
 and light availability. The experiment focused on how mismatches between
 the mycorrhizal type of focal seedlings and neighboring adult trees alter
 survival outcomes through soil biotic legacies and trait-mediated
 mechanisms. Five temperate tree species differing in mycorrhizal
 association were used: *Acer rubrum*, *Acer saccharum*, *Prunus serotina*
 (arbuscular mycorrhizal; AMF-associated), and *Quercus alba* and *Quercus
 rubra* (ectomycorrhizal; EMF-associated). Soils were collected beneath
 mapped adult trees in a mixed hardwood forest and represented both
 conspecific and heterospecific soil sources spanning 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. Seedlings were grown under contrasting light
 environments to test interactions between soil source and aboveground
 resource availability. Survival was monitored through time and analyzed
 using time-to-event (survival) models. **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 representing understory to gap-like conditions were created
 using shade cloth: low (~2% full sunlight), medium (~15% full sunlight),
 and high (~30% full sunlight). Seedlings were planted into pots containing
 a 1:1 mixture of field-collected soil and potting substrate. Soil sources
 were derived from individual adult trees of known species identity. Pots
 were arranged across multiple greenhouse benches to account for spatial
 heterogeneity, with bench included as a random effect in analyses.
 Seedling survival was monitored repeatedly through time. Time-to-event
 data were recorded, with mortality events coded explicitly and surviving
 individuals censored at the end of the experiment. In addition to survival
 outcomes, seedling functional traits associated with carbon storage and
 defense (non-structural carbohydrates, lignin, and phenolics) and
 mycorrhizal colonization metrics were measured for a sub-sample of
 seedlings at three weeks after planting to evaluate mechanistic pathways
 linking soil source to survival. ### Files and variables #### File:
 GH_Data.csv **Description:** Greenhouse seedling survival experiment #####
 Variables * **Number**: Unique seedling identifier * **Species**: Seedling
 species * ACRA = *Acer rubrum* * ACSA = *Acer saccharum* * PRSE = *Prunus
 serotina* * QUAL = *Quercus alba* * QURU = *Quercus rubra* * **SpMyco**:
 Seedling mycorrhizal association * AMF = arbuscular mycorrhizal * EMF =
 ectomycorrhizal * **Light**: Light treatment * Low (~2% full sunlight) *
 Med (~15% full sunlight) * High (~30% full sunlight) * **SoilSt**: Soil
 source type * Nonsterile * Sterile * **SoilCon**: Indicator of conspecific
 soil (binary or categorical, as used in analyses) * Conspecific – live
 soil cultured by same species of adult tree as seedling * Heterospecific –
 live soil cultured by different species of adult tree as seedling *
 Sterile – gamma irradiated soil cultured by same species of adult tree as
 seedling * **SoilSp**: Species identity of soil-source adult * ACRA =
 *Acer rubrum* * ACSA = *Acer saccharum* * PRSE = *Prunus serotina* * POGR
 = *Populus grandidentata* * QUAL = *Quercus alba* * QURU = *Quercus rubra*
 * **SoilMyco**: Mycorrhizal association of soil-source adult * AMF =
 arbuscular mycorrhizal fungi * EMF = ectomycorrhizal fungi * Sterile =
 gamma irradiated soil * **SoilSpec**: Soil-source category * Con = live
 soil cultured by same species of adult tree as seedling * ConSter = gamma
 irradiated soil cultured by same species of adult tree as seedling *
 HetAMF = live soil cultured from an arbuscular mycorrhizal
 (AMF)-associated adult tree of a different species than the seedling *
 HetEMF = live soil cultured from an ectomycorrhizal (AMF)-associated adult
 tree of a different species than the seedling * **Adult**: Unique
 identifier for adult tree soil source * **Bench**: Greenhouse bench
 location * **Time**: Time to event or censoring (days) * **Event**:
 Survival status * 1 = mortality event * 0 = censored (alive at end of
 monitoring period) * **AMF**: Arbuscular mycorrhizal colonization (%) *
 **EMF**: Ectomycorrhizal colonization (%) * **NSC**: Non-structural
 carbohydrate concentration (mg g⁻¹ dry mass) * **Lignin**: Lignin
 concentration (% dry mass) * **Phenolics**: Total phenolic concentration
 (mg g⁻¹ dry mass; gallic acid equivalents) * **AMF_Imp**: Imputed AMF
 colonization values (where applicable) * **EMF_Imp**: Imputed EMF
 colonization values (where applicable) * **NSC_Imp**: Imputed
 non-structural carbohydrate values * **LIG_Imp**: Imputed lignin values *
 **PHN_Imp**: Imputed phenolic values Cells with no available data are
 coded as blanks and **NA**. ## Code/software All analyses were conducted
 within a Bayesian framework to evaluate how plant–soil feedbacks (PSFs)
 vary with mycorrhizal matching, soil source, and light availability.
 Seedling survival was analyzed using species-specific Cox proportional
 hazards models formulated as individual-based counting processes, with
 time-to-event data censored at harvest. Models included soil source and
 light availability as fixed effects and greenhouse bench as a random
 effect, and were fit in OpenBUGS (v1.4) using Markov chain Monte Carlo
 methods. Predicted survival probabilities were derived from posterior
 distributions of the hazard and risk functions, fully propagating
 parameter uncertainty, and PSFs were quantified as differences in
 predicted survival between conspecific and heterospecific soil sources
 within each light level. Trait expression and mycorrhizal colonization
 were analyzed using linear mixed models and fixed-effects ANOVA in IBM
 SPSS Statistics (v30), with soil source and light as fixed effects and
 bench as a random effect where applicable.