Data from: Grazing regimes shape beetle and ant biodiversity in cork oak woodlands

Verdinelli, Marcello 1 ; Fadda, Maria Leonarda1 ; Arrizza, Stefano1 ; Mannu, Roberto2

Research facility: Fieldwork conducted across Mediterranean cork oak woodlands in northern Sardinia, Italy

Published Apr 09, 2026 on Dryad. https://doi.org/10.5061/dryad.j9kd51csz

Data files

Apr 09, 2026 version files 21.93 KB

Abstract

This dataset includes environmental, ecological, and functional trait data collected in 2016 from eighteen Mediterranean cork oak woodland sites in northern Sardinia, Italy, subjected to sheep grazing, cattle grazing, or long‑term grazing exclusion. The dataset contains: (1) environmental descriptors such as altitude, vegetation cover, canopy cover, shrub cover, tree density, tree diameter at breast height, and average tree height; (2) ground beetle (Coleoptera: Carabidae) abundance data from standardized pitfall trapping across spring, summer, and autumn sampling periods; (3) ant (Hymenoptera: Formicidae) occurrence frequencies derived from trap captures; and (4) species‑level functional traits for both taxa obtained from literature and trait databases. Environmental information was generated through field measurements, satellite image analysis, and object‑based image classification, while insect specimens were identified using standard taxonomic keys. These data support analyses of species richness, functional diversity, community composition, and their relationships with grazing regimes and environmental gradients. The dataset is suitable for reuse in biodiversity monitoring, functional trait ecology, multitaxon comparisons, and land‑use impact evaluations in Mediterranean ecosystems.

Dataset DOI: 10.5061/dryad.j9kd51csz

Description of the data and file structure

This dataset was generated to assess how different grazing regimes influence ground beetle (Coleoptera: Carabidae) and ant (Hymenoptera: Formicidae) communities in Mediterranean cork oak woodlands.

Sampling was conducted across multiple woodland sites, each classified into one of three grazing treatments: CG = cattle grazing, SG = sheep grazing, NG = no grazing.
Ground beetles were collected using standardized pitfall trapping arrays, producing abundance data.
Ant communities were sampled using pitfall traps and/or visual searching, producing occurrence (capture frequency) data.
Environmental descriptors—including vegetation cover, canopy closure, tree metrics, and shrub structure—were recorded using standard field protocols.
Functional traits for each species were compiled from published literature, databases, and expert knowledge.

These are the included files:

Environmental_variables.csv
Insect_species.csv
Functional_traits.csv

In the “Functional traits” table, cells containing the symbol “–” do not represent missing data but indicate values that are not applicable. This is because different functional traits were used for ground beetles and ants, and several traits are taxon-specific. In addition, we deliberately kept two separate columns for body size, namely “Mean body size” for ground beetles and “Worker size” for ants. This distinction was made because, in ants, body size measurements clearly refer specifically to the worker caste, whereas ground beetle body size refers to adult individuals without caste differentiation. Keeping these columns separate avoids ambiguity and ensures biological clarity and taxon-specific interpretability of the data. Mean body size for ground beetles and Worker size for ants are quantitative data. The other traits are qualitative data and were treated as ordinal, and/or binary data. In Environmental variables, Shrub cover was visually estimated using an ordinal scale (0–5): Absent = 0; Very low = 1; Low = 2; Medium = 3; Medium high = 4; High =

Code/software

R version

R 4.3.2 (R Core Team, 2023)

R packages used in analysis

FD (version 1.0‑12.3)
Used to calculate Functional Dispersion (FDis) and other functional diversity metrics.
vegan (version 2.6‑6.1)
Used for multivariate analyses including:
- NMDS (metaMDS)
- PERMANOVA (adonis)
- Bray–Curtis dissimilarities
- Principal Coordinates Analysis (cmdscale, capscale)
- db‑RDA
- Procrustes analysis (protest)
- SIMPER analyses (simper)
indicspecies (version 1.7.14)
Used for Indicator Species Analysis (ISA) with permutation testing.
stats (base R package)
Used for Kruskal–Wallis tests, pairwise comparisons, and general statistical procedures.

Software used during environmental data generation

(These programs are not required to reuse the data; all outputs are provided as CSV.)

Google Earth Pro (free; used for canopy cover estimation)
GIMP 2.8 (open‑source; used for image preparation)
Trimble eCognition Developer (used for vegetation segmentation; no proprietary project files included)
No scripts or executable code are included with this dataset. All derived variables are already provided in final CSV format, and no additional processing is required to reuse the data.