Data from: Herbivore species and patch heterogeneity modulate grazing-induced shifts in soil nematode trophic structure and energy flux

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.