Questions:

Structurally dominant species can be especially influential in plant community assembly and ecosystem function as Species of Unusual Effect (SUEs). For example, native bunchgrasses function as foundation species and ecosystem engineers in the naturally high-diversity groundcover of longleaf pine savannas. Other species structurally dominate relatively small, discrete patches across the savanna landscape, e.g., the fern Pteridium aquilinum and the shrub Ilex glabra. Do patch-level species richness and composition of assemblages of groundcover plants and arthropods differ among alternative locally dominant species?

Location:

We conducted our study in a restored longleaf pine savanna in southeastern Louisiana.

Methods:

We compared the groundcover plant and arthropod assemblages within discrete patches structurally dominated by P. aquilinum or I. glabra to adjacent areas physically dominated by native bunchgrasses. We compared local plant species richness and composition, stem density, aboveground dry biomass, and litter dry biomass, as well as arthropod species richness and composition, abundance, and dry biomass.

Results:

Species richness and stem density of non-dominant groundcover plants were significantly lower in patches of P. aquilinum and I. glabra than within bunchgrass-dominated areas. Species composition of non-dominant groundcover plants was more variable within I. glabra patches compared to bunchgrass areas. Arthropod species richness and abundance were also significantly lower in patches of P. aquilinum compared to bunchgrass areas, and species composition of arthropods differed significantly between P. aquilinum patches and bunchgrass areas.

Conclusions:

At the local scale of groundcover plant patches (along with their attendant arthropods) in a longleaf pine savanna in southeastern Louisiana, native bunchgrasses are associated with higher species richness compared to the alternative foundation species P. auilinum or I. glabra. Although removal experiments, community-assembly experiments, or reciprocal replacement experiments should be conducted to test the hypothesis that these species differentially influence the groundcover as, respectively, diversity-enhancing vs. diversity-inhibiting SUEs, our observations exemplify how alternative foundation species could add complexity to natural landscapes by differentially influencing characteristics of their associated local communities.

R Scripts and data files to perform analyses and create figures for ‘Alternative foundation species differentially influence diversity of groundcover plant and arthropod assemblages among patches in a pine savanna in the southeastern U.S.A. ’ This study examines the effect of alternative foundation species on the diversity of non-foundation groundcover plant species and arthropods within a longleaf pine savanna in southeastern Louisiana.

Data files:

fern.diversity.csv
- This file contains species richness, stem density, and aboveground biomass (g) of non-foundation groundcover plants as well as litter biomass (g) from inside and outside of bracken fern patches. Note: Outside of bracken fern patches is within bunchgrass dominated areas.
fern.NMDS.csv
- This file contains a species-by-site matrix used in NMDS (nonmetric multidimensional scaling) for non-foundation groundcover plants inside and outside of bracken fern patches. Each row is a quadrat and each column is a non-foundation groundcover plant species. Note: Outside of bracken fern patches is within bunchgrass dominated areas.
fern.env.NMDS.csv
- This file contains location information for each quadrat in the species-by-site matrix of non-foundation groundcover plants inside and outside of bracken fern patches used in NMDS. Each row is a quadrat and each column gives the plot id, quadrat type (1=In, 2=Out), and quadrat id for each quadrat. Note: Outside of bracken fern patches is within bunchgrass dominated areas.
fern.iNext.csv
- This file contains incidence data of non-foundation groundcover plants inside and outside of bracken fern patches. Each row represents a plot, either from inside or outside of bracken fern patches. Note: Outside of bracken fern patches is within bunchgrass dominated areas.
gallberry.diversity.csv
- This file contains species richness, stem density, and aboveground biomass (g) of non-foundation groundcover plants as well as litter biomass (g) from inside and outside of gallberry patches. Note: Outside of gallberry patches is within bunchgrass dominated areas.
gallberry.NMDS.csv
- This file contains a species-by-site matrix used in NMDS (nonmetric multidimensional scaling) for non-foundation groundcover plants inside and outside of gallberry patches. Each row is a quadrat and each column is a non-foundation groundcover plant species. Note: Outside of gallberry patches is within bunchgrass dominated areas.
gallberry.env.NMDS.csv
- This file contains location information for each quadrat in the species-by-site matrix of non-foundation groundcover plants inside and outside of gallberry patches used in NMDS. Each row is a quadrat and each column gives the plot id, quadrat type (1=In, 2=Out), and quadrat id for each quadrat. Note: Outside of gallberry patches is within bunchgrass dominated areas.
gallberry.iNext.csv
- This file contains incidence data of non-foundation groundcover plants inside and outside of gallberry patches. Each row represents a plot, either from inside or outside of gallberry patches. Note: Outside of gallberry patches is within bunchgrass dominated areas.
arthropod.sweep.diversity.csv
- This file contains species richness, abundance, and biomass (g) of arthropods collected from sweep samples from inside and outside of bracken fern patches. Note: Outside of bracken fern patches is within bunchgrass dominated areas.
arthropod.sweep.NMDS.csv
- This file contains a species-by-site matrix used in NMDS (nonmetric multidimensional scaling) for arthropods collected from sweep net samples inside and outside of bracken fern patches. Each row is a patch and each column is an arthropod species. Note: Outside of bracken fern patches is within bunchgrass dominated areas.
arthropod.sweep.env.NMDS.csv
- This file contains location information for each patch in the species-by-site matrix of sweep net collected arthropods inside and outside of bracken fern patches used in NMDS. Each row is a patch and each column gives the plot id and quadrat type (1=In, 2=Out). Note: Outside of bracken fern patches is within bunchgrass dominated areas.
sweep.iNext.csv
- This file contains incidence data of sweep net collected arthropods inside and outside of bracken fern patches. Note: Outside of bracken fern patches is within bunchgrass dominated areas.

13. species.codes.csv

-This file contains scientific names for each six letter plant species code used in the NMDS analyses.

Analysis script:

RScript-Alternative_foundation_species_differentially_influence_diversity_of_groundcover_plant_and_arthropod_assemblages_among_patches_in_a_pine_savanna_in_the_southeastern_usa.R
- This file contains scripts to run all main analyses and reproduce figures from the paper. Please read all annotations carefully when conducting these analyses.

Contrasting species richness in patches of alternative foundation species suggests a framework for understanding Species of Unusual Effect

Data files

Abstract

Contrasting species richness in patches of alternative foundation species suggests a framework for understanding Species of Unusual Effect

Data files

Abstract

README: Contrasting species richness in patches of alternative foundation species suggests a framework for understanding Species of Unusual Effect

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