Diversity Patterns and Ecological Network Features of Soil Mite Trophic Groups in Karst Cave Ecosystems

Trophic niche differentiation alleviates interspecific competition among soil fauna by modulating resource utilization and allocation, offering a novel perspective for understanding biodiversity maintenance and species coexistence in subterranean ecosystems. As a typical example of an oligotrophic and extremely dark environment, karst cave soils support arthropod communities that are functionally distinct from those in surface habitats. However, systematic understanding of the multidimensional diversity patterns and ecological network complexity of multitrophic groups of cave-dwelling soil mites remains limited. In this study, soil mite samples were collected from distinct photic zones of the cave including the dark, twilight, light, and entrance zones. We aimed to uncover the variation in α, β, and functional diversity among multitrophic groups (including predators and decomposers), and constructed ecological networks to examine patterns of biotic interactions and species coexistence. The results showed that along the cave environmental gradient, the α-diversity of different trophic groups increased, while functional diversity exhibited a contrasting trend. In addition, except for predator groups, the β-diversity of soil mites did not differ significantly among cave microhabitats and was primarily driven by species replacement processes. Moreover, the complexity of ecological networks progressively increased along the cave gradient, indicating that interactions among multitrophic groups intensified, with predatory mites playing a central role in maintaining network stability. Notably, no indicator species were found in the dark zone, which represents the core oligotrophic habitat within caves. Our study demonstrates that, compared to surface habitats such as cave entrances and adjacent agricultural lands, cave soil environments support simpler community composition, diversity, and ecological network complexity across different trophic groups of mites. Furthermore, predatory mites not only serve as keystone taxa within cave habitats, but also play a pivotal role in mediating interactions among trophic groups. These findings provide important theoretical insights for understanding community assembly processes under extreme environmental conditions, maintaining ecosystem stability, and supporting the conservation of subterranean biodiversity.