Data from: Plant-soil feedbacks affect hardwood regeneration in mountain laurel (Kalmia latifolia) thickets
Data files
Jul 20, 2026 version files 237 KB
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DRYAD_2024seedlingAbundance.csv
2.35 KB
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DRYAD_adultgrowth.csv
11.76 KB
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DRYAD_BiomassGH2.csv
805 B
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DRYAD_emergenceGH1.csv
3.51 KB
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DRYAD_EmergenceGH2.csv
731 B
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DRYAD_OxarBiomassGH1.csv
2.66 KB
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DRYAD_oxarsurvival.csv
4.88 KB
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DRYAD_QualBiomassGH1.csv
5.50 KB
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DRYAD_saplingdata.csv
190.36 KB
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DRYAD_seedlingabundance.csv
3.78 KB
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README.md
10.67 KB
Abstract
Ericaceous thickets inhibit hardwood regeneration, particularly of ectomycorrhizal tree species, yet mechanisms underlying effects of the ericaceous shrub Kalmia latifolia remain unclear. We explored these effects using spatial analyses of a forest stand and two greenhouse experiments testing plant-soil feedbacks (PSFs), their biotic basis, and light dependence. Spatial analyses confirmed that seedling abundance for most species was negatively correlated with K. latifolia basal area. Oaks (Quercus spp.) recruiting to the sapling stage occurred in areas with less K. latifolia than those where arbuscular or ericoid mycorrhiza-associated saplings established. Greenhouse Experiment 1 showed Quercus alba emergence was greater in conspecific than K. latifolia-conditioned soils under sterile conditions, indicating a negative abiotic effect of K. latifolia soil on oak emergence. In nonsterile treatments, soil microbes partially offset this effect and enhanced Q. alba emergence relative to sterilized K. latifolia soil. Seedling growth was greater in conspecific soil under low light, reflecting a positive, biotically mediated, light-dependent PSF. Seedlings of another ericaceous species, Oxydendrum arboreum, had greater survival and growth in K. latifolia soil than conspecific soil, but negative PSFs were not consistently biotically mediated or stronger in low light. Greenhouse Experiment 2 showed Q. alba emergence was lower in soils conditioned by Vaccinium spp., O. arboreum, and K. latifolia at 6 weeks, but not at 12 weeks, suggesting delayed emergence may characterize ericoid-conditioned soils. Collectively, results indicate that ericaceous shrubs constrain oak regeneration through stage-specific PSFs that interact with light and microbes, with implications for managing oak recruitment in mixed hardwood forests.
Dataset DOI: 10.5061/dryad.1jwstqkb0
Description of the data and file structure:
Cells with no data were coded as NA.
File: DRYAD_seedlingabundance.csv
Description: Seedling abundance vs. K. latifolia basal area.
This data was collected in 2023 at Franklin State Forest in Tennessee, USA. One contiguous hectare was divided into 10m x 10m plots, which were numbered 1-100. K. latifolia diameter was measured at the root collar. Seedling abundance for each species is reported as a binned value - 0 (0), 1 (1), 2 (2-7), 3 (8-25), and 4 (>25). Vaccinium spp. were not identified to species level for this study. All woody stems <50 cm in height are considered seedlings for the purpose of this study.
Variables:
- Plot: plot number, 1-100
- Basal area: The sum of all K. latifolia basal area in a plot in square centimeters (cm^2).
- QUA: Quercus alba abundance
- QUVE: Quercus velutina abundance
- LITU: Liriodendron tulipifera abundance
- OXAR: Oxydendrum arboretum abundance
- QUCO: Quercus coccinea abundance
- ACRU: Acer rubrum abundance
- NYSY: Nyssa sylvatica abundance
- VACC: Vaccinium spp. abundance
- QUMO: Quercus montana abundance
- SAAL: Sassafras albidum abundance
- DIVI: Diospyros virginiana abundance
File: DRYAD_2024seedlingAbundance.csv
Description: Quercus seedling abundance in 2024 vs. K. latifolia basal area.
This data was collected in 2024 at Franklin State Forest in Tennessee, USA. One contiguous hectare was divided into 10 m × 10 m plots, which were numbered 1–100. K. latifolia diameter was measured at the root collar. Seedling abundance for each species is reported as a binned value: 0 (0), 1 (1), 2 (2–7), 3 (8–25), and 4 (>25). All woody stems <50 cm in height are considered seedlings for the purpose of this study.
Variables:
- Plot: Plot number, 1–100
- Basal area: The sum of all K. latifolia basal area in a plot in square centimeters (cm²).
- QUMO: Quercus montana abundance
- QUCO: Quercus coccinea abundance
- QUVE: Quercus velutina abundance
- QUAL: Quercus alba abundance
File: DRYAD_saplingdata.csv
Description: K. latifolia basal area within 5 m of saplings.
This data was collected in 2023 at Franklin State Forest in Tennessee, USA. Saplings were defined as woody stems 50–140 cm in height. K. latifolia diameter was measured at the root collar.
Variables:
- Sapling_ID: Unique identifier for each sapling. Values are not continuous because these ID numbers are part of a larger dataset.
- KALA: Cumulative K. latifolia basal area within a 5 m radius of each sapling, reported in square centimeters (cm²).
- Sapling_Spp: Sapling species.
- Sapling_Myco: Sapling mycorrhizal association. AM = arbuscular mycorrhiza, ECM = ectomycorrhiza, ERM = ericoid mycorrhiza.
File: DRYAD_adultgrowth.csv
Description: Growth of adult trees vs. proximate K. latifolia basal area.
This dataset was collected in 2023 at Franklin State Forest in Tennessee, USA. Adult trees were defined as woody stems >140 cm in height. K. latifolia diameter was measured at the root collar, while all other species were measured at 140 cm (standard diameter at breast height).
Variables:
- OBJECTID: Unique identifier for each tree.
- Species: Species name for each tree, abbreviated using standard FIA codes.
- Change_ba: Change in tree basal area from 2015–2023, measured in square centimeters (cm²).
- MycoType: Mycorrhizal association of each tree. AM = arbuscular mycorrhiza, ECM = ectomycorrhiza, ERM = ericoid mycorrhiza.
- KALA_ba: Cumulative K. latifolia basal area within 5 m of each tree.
File: DRYAD_oxarsurvival.csv
Description: Oxydendrum arboreum survival analysis (Greenhouse experiment 1).
This dataset comes from a greenhouse plant-soil feedback experiment conducted in 2023. Soils were collected between December 2022 and January 2023 from the upper 15 cm of soil within 1 m of the bole of four randomly selected adult trees in the top DBH quartile of each species (O. arboreum and K. latifolia). Treated soil was sterilized by two autoclave cycles for 30 minutes at 121 °C, 24 h apart. Light treatments were created using shade cloths that replicated conditions inside and outside of ericaceous thickets. Seedlings were censused three times per week for 12 weeks.
Variables:
- no: Seedling identification number.
- SoilSp: Species under which soil was collected. 1 = conspecific (O. arboreum), 2 = heterospecific (K. latifolia).
- Tr: Soil treatment group. 1 = sterile, 2 = nonsterile.
- Li: Light treatment. 1 = high light, 2 = low light.
- InitialH: Initial stem height, in millimeters.
- InitialS: Z-score standardized value of InitialH.
- Event: Whether mortality occurred. 1 = mortality occurred during the experiment, 2 = mortality did not occur during the experiment.
- Last: Census at which mortality was first recorded.
File: DRYAD_emergenceGH1.csv
Description: Quercus alba emergence analysis (Greenhouse experiment 1).
This dataset comes from a greenhouse plant-soil feedback experiment conducted in 2023. Soils were collected between December 2022 and January 2023 from the upper 15 cm of soil within 1 m of the bole of four randomly selected adult trees in the top DBH quartile of each species (Q. alba and K. latifolia). Treated soil was sterilized by two autoclave cycles for 30 minutes at 121 °C, 24 h apart. Light treatments were created using shade cloths that replicated conditions inside and outside of ericaceous thickets. Seedlings were censused three times per week for 12 weeks. Seedlings were planted after germination but before emergence.
Variables:
- ID: Seedling identification number.
- Soil: Species under which soil was collected. Kala = K. latifolia, Qual = Q. alba.
- Treatment: Soil treatment group. S = sterile, NS = nonsterile.
- Light: Light treatment.
- Emergence: Whether the seedling emerged. 1 = emerged, 0 = did not emerge.
- EmergenceSpan: Number of days between planting and emergence.
File: DRYAD_QualBiomassGH1.csv
Description: Quercus alba biomass analysis (Greenhouse experiment 1).
This dataset comes from a greenhouse plant-soil feedback experiment conducted in 2023. Soils were collected between December 2022 and January 2023 from the upper 15 cm of soil within 1 m of the bole of four randomly selected adult trees in the top DBH quartile of each species (Q. alba and K. latifolia). Treated soil was sterilized by two autoclave cycles for 30 minutes at 121 °C, 24 h apart. Light treatments were created using shade cloths that replicated conditions inside and outside of ericaceous thickets. Seedlings were harvested after 12 weeks and considered alive if live root tissue was present at harvest. All live tissue was dried at 70 °C for 48 hours before weighing. Because some root tissue was reserved for future mycorrhizal analyses, fresh:dry ratios were used to estimate dry root mass.
Variables:
- Pot: Seedling identification number.
- Soil: Species under which soil was collected. Kala = K. latifolia, Qual = Q. alba.
- Trtmt: Soil treatment group. S = sterile, NS = nonsterile.
- Light: Light treatment.
- DryMass: Total seedling dry mass, in milligrams.
- InitialDryMass: Estimated seedling dry mass at planting, in milligrams, calculated using fresh:dry ratios.
File: DRYAD_OxarBiomassGH1.csv
Description: Oxydendrum arboreum biomass analysis (Greenhouse experiment 1).
This dataset comes from a greenhouse plant-soil feedback experiment conducted in 2023. Soils were collected between December 2022 and January 2023 from the upper 15 cm of soil within 1 m of the bole of four randomly selected adult trees in the top DBH quartile of each species (O. arboreum and K. latifolia). Treated soil was sterilized by two autoclave cycles for 30 minutes at 121 °C, 24 h apart. Light treatments were created using shade cloths that replicated conditions inside and outside of ericaceous thickets. Seedlings were harvested after 12 weeks and dried at 70 °C for 48 hours before weighing. Because some root tissue was reserved for future mycorrhizal analyses, regression equations were used to estimate dry root mass.
Variables:
- Pot: Seedling identification number.
- Soil: Species under which soil was collected. Kala = K. latifolia, Oxar = O. arboreum.
- Trtmt: Soil treatment group. S = sterile, NS = nonsterile.
- Light: Light treatment.
- Mass: Total seedling dry mass, in milligrams.
File: DRYAD_BiomassGH2.csv
Description: Quercus alba biomass analysis (Greenhouse experiment 2).
This dataset comes from a greenhouse plant-soil feedback experiment conducted in 2024. Soils were collected in December 2023 from the upper 15 cm of soil within 1 m of the bole of four randomly selected adult trees in the top DBH quartile of each species (Q. alba, O. arboreum, K. latifolia, and Vaccinium spp.). Because Vaccinium has a shrubby growth form, soil was collected based on stem density within mapped stands rather than DBH. Seedlings were harvested 125 days after planting and dried at 70 °C for 48 hours.
Variables:
- Pot: Seedling identification number.
- SoilType: Species under which soil was collected. Qual = Q. alba, Kala = K. latifolia, Oxar = O. arboreum, Vacc = Vaccinium spp.
- TotalMass: Total dry mass, in milligrams.
File: DRYAD_EmergenceGH2.csv
Description: Quercus alba emergence analysis (Greenhouse experiment 2).
This dataset comes from a greenhouse plant-soil feedback experiment conducted in 2024. Soils were collected in December 2023 from the upper 15 cm of soil within 1 m of the bole of four randomly selected adult trees in the top DBH quartile of each species (Q. alba, O. arboreum, K. latifolia, and Vaccinium spp.). Because Vaccinium has a shrubby growth form, soil was collected based on stem density within mapped stands rather than DBH. Germinated seeds were planted and censused three times per week for emergence throughout the experiment.
Variables:
- no: Seedling identification number.
- Soil: Species under which soil was collected. 1 = Q. alba, 2 = Vaccinium spp., 3 = O. arboreum, 4 = K. latifolia.
- InitialS: Initial seedling mass, in milligrams.
- Event: Whether emergence occurred. 1 = seedling emerged, 0 = seedling did not emerge.
- Last: Census at which emergence was first recorded. Individuals that did not emerge were assigned the final census date.