DOI: 10.5061/dryad.7pvmcvf6q
title: Data from: Herbivore species and patch heterogeneity modulate grazing-induced shifts in soil nematode trophic structure and energy flux

description: Grazing by large herbivores is a critical factor in shaping grassland
 biodiversity and ecosystem functioning worldwide; however, its
 consequences for soil communities remain poorly understood. This gap is
 important because soil food webs underpin ecosystem processes and may
 respond differently to grazing depending on herbivore identity and local
 heterogeneity (i.e., patchiness). Here, a four-year field experiment was
 conducted to investigate the influence of cattle and sheep grazing on soil
 nematode communities in a grassland featuring a mosaic of degraded
 high-salinity and undegraded low-salinity patches. We focus on nematode
 communities because nematode-based indices offer key insights into the
 structure of the soil food web and overall soil health. In the absence of
 grazing, degraded patches exhibited a more simplified soil food web
 structure, indicated by reduced nematode diversity, maturity index, and
 structure index, but higher nematode biomass and energy flux compared to
 undegraded patches. However, sheep grazing reduced total nematode biomass
 and energy flux in degraded patches, while cattle grazing decreased the
 biomass of higher trophic levels (i.e., omnivores and predators), the
 energy flux from lower to higher trophic levels, and flow uniformity in
 undegraded patches. These effects resulted from declines in the abundance
 of large-bodied nematodes, primarily limited by soil pore space and soil
 microbial biomass. Collectively, our findings demonstrate that livestock
 grazing can exacerbate soil degradation by inhibiting soil fauna
 communities, but the outcomes are patch- and herbivore-specific. By
 combining nematode structural and functional indices, our study advances
 understanding of how herbivore identity interacts with fine-scale
 grassland heterogeneity to regulate soil food webs. This framework
 provides a new pathway for linking grazing management to soil health,
 offering a scientific basis for adaptive policies that balance production
 goals with sustainable grassland restoration under environmental change.
description: # Data from: Herbivore species and patch heterogeneity modulate
 grazing-induced shifts in soil nematode trophic structure and energy flux
 Dataset DOI:
 [10.5061/dryad.7pvmcvf6q](https://doi.org/10.5061/dryad.7pvmcvf6q) ##
 Description of the data and file structure Soil samples were collected at
 the end of the 2020 growing season from grazed grassland paddocks
 comprising high- and low-salinity patches, with two replicates in
 high-salinity patches and four in low-salinity patches, reflecting their
 proportional area coverage. Composite soil cores (0–10 cm depth) were
 obtained and divided for different analyses. Fresh subsamples were used to
 extract nematodes via modified Baermann funnels and to determine soil
 water content. Other subsamples were analyzed for microbial biomass carbon
 and nitrogen, available nitrogen, and soil physicochemical properties,
 including pH, electrical conductivity, total organic carbon, total
 nitrogen, and total phosphorus. Nematodes were identified to genus or
 family level under a compound microscope, and their body sizes were
 measured to estimate biomass. Multiple abundance-based and size-based
 indices were then calculated to characterize soil food-web structure,
 ecosystem functioning, and nematode energy fluxes across trophic groups.
 ### Files and variables #### File: Data_FE_FE-2025-00968.R1.xlsx
 **Description:**  Data columns include blocks, grazing treatments, patch
 types, and plot information, as well as the abundance, community-weighted
 mean body weight, and biomass of total nematodes and each trophic group.
 The data also contains nematode abundance-based structural indices,
 size-based energy flux metrics, and associated soil physicochemical
 properties. Blocks: 1, 2, 3 * Grazing: Ungrazing, Cattle grazing, Sheep
 grazing * Patch: Low salinity patches, High salinity patches * Replicates:
 1–2 replicates in low salinity patches, 1–4 replicates in high salinity
 patches * Total nematode abundance (indiv. / 100g dry soil): Abundance of
 total nematodes * Abundance_He (indiv. / 100g dry soil): Abundance of
 herbivores * Abundance_Ba (indiv. / 100g dry soil): Abundance of
 bacterivores * Abundance_Fu (indiv./100g dry soil): Abundance of
 fungivores * Abundance_OP (indiv./100g dry soil): Abundance of
 omnivores-predators * Total nematode cwmW (μg): Community weighted mean
 weight of total nematodes * cwmW_He (μg): Community weighted mean weight
 of herbivores * cwmW_Ba (μg): Community weighted mean weight of
 bacterivores * cwmW_Fu (μg): Community weighted mean weight of fungivores
 * cwmW_OP (μg): Community weighted mean weight of omnivores-predators *
 Total nematode biomass (μg/100g dry soil): Biomass of total nematodes *
 Biomass_He (μg/100g dry soil): Biomass of herbivores * Biomass_Ba (μg/100g
 dry soil): Biomass of bacterivores * Biomass_Fu (μg/100g dry soil):
 Biomass of fungivores * Biomass_OP (μg/100g dry soil): Biomass of
 omnivores-predators * Nematode Shannon-Wiener index * Nematode trophic
 diversity * Plant parasite index * Maturity index * Maturity index 2–5 *
 Sigma maturity index * Basal index * Enrichment index * Structure index *
 Nematode channel ratio * Relative abundance_He (%): Relative abundance of
 herbivores * Relative_abundance_Ba (%): Relative abundance of bacterivores
 * Relative_abundance_Fu (%): Relative abundance of fungivores *
 Relative_abundance_OP (%): Relative abundance of omnivores-predators *
 Flux_Resource_He (μg C / 100g dry soil / day): Energy flux from resource
 to herbivores * Flux_Resource_Ba (μg C / 100g dry soil / day): Energy flux
 from resource to bacterivores * Flux_Resource_Fu (μg C / 100g dry soil /
 day): Energy flux from resource to fungivores * Flux_He_OP (μg C / 100g
 dry soil / day): Energy flux from herbivores to omnivores-predators *
 Flux_Ba_OP (μg C / 100g dry soil / day): Energy flux from bacterivores to
 omnivores-predators * Flux_Fu_OP (μg C / 100g dry soil / day): Energy flux
 from fungivores to omnivores-predators * Total energy flux (μg C / 100g
 dry soil / day) * Flow uniformity * Microbial biomass carbon (mg/kg) *
 Microbial biomass nitrogen (mg/kg) * Soil water content (%) * pH *
 Electrical conductivity (μS/cm) * Soil bulk density (g/cm³) * Soil total
 organic carbon (g/kg) * Soil total nitrogen (g/kg) * Soil total phosphorus
 (g/kg) * Soil carbon_nitrogen ratio * Soil carbon_phosphorus ratio * Soil
 nitrogen_phosphorus ratio * Soil NH4-N (mg/kg): Soil NH₄⁺-N content * Soil
 NO3-N (mg/kg): Soil NO₃⁻-N content ## Code/software All data analyses were
 conducted using **R software (version 4.4.0; R Core Team, 2024)**, which
 is freely available under an open-source license
 ([https://www.r-project.org/](https://www.r-project.org/)). The workflow
 involved fitting mixed-effect linear models to evaluate the effects of
 grazing treatments, patch types, and their interaction on nematode
 community metrics and soil properties. Fixed effects included grazing
 treatment, patch type, and their interaction, while nested random effects
 accounted for sample replication within blocks. **Tukey’s post hoc tests**
 were applied to determine pairwise differences. Community composition was
 analyzed using **nonmetric multidimensional scaling (NMDS)** based on
 Bray–Curtis distances and **PERMANOVA** (adonis2) with **PERMDISP2** to
 test for multivariate homogeneity of dispersions. **Redundancy analysis
 (RDA)** with forward selection and permutation tests (999 runs) identified
 key environmental drivers. **Linear regression analyses** were further
 used to assess relationships between nematode energy flux, flow
 uniformity, and environmental factors. The main R packages used include
 *vegan*, *lme4*, *multcomp*, *ggplot2*, and *car*. ## Access information
 Other publicly accessible locations of the data: * The dataset described
 here is original and not deposited elsewhere. No other publicly accessible
 locations exist. Data was derived from the following sources: * All data
 were generated from field experiments and laboratory analyses conducted by
 the authors. No data were derived from previously published or publicly
 available datasets.