Soil moisture is associated with belowground biotic recovery across vegetation restoration systems

Abstract

Karst rocky desertification is a severe form of land degradation in southwest China, where vegetation restoration has been widely implemented to rebuild soil habitat and biodiversity. However, how restoration‐associated changes in soil conditions correspond to belowground biotic recovery remains poorly understood. We compared soil habitat conditions and soil micro‐food web (SMFW) structure across six vegetation restoration systems at the Huajiang Rocky Desertification Control Station to identify habitat attributes and soil biotic indicators associated with belowground recovery. Soil physicochemical properties, microbial communities, nematode trophic groups, and metabolic footprints were assessed using univariate analyses, exploratory redundancy analysis (RDA), and structural equation modeling (SEM). Restoration systems differed markedly in soil moisture, bulk density, nutrient status, microbial attributes, and nematode trophic organization. Among the measured habitat variables, soil moisture showed the most consistent associations with belowground biotic patterns. Systems with greater moisture retention were generally associated with higher bacterial abundance, larger total nematode populations, greater omnivore‐predator abundance, and more developed food‐web structure, whereas drier and more physically constrained systems were associated with more limited belowground development. Fungal‐fungivore associations were comparatively weak. Exploratory RDA revealed multivariate associations among soil, microbial, and nematode attributes, while SEM indicated that moisture‐associated microbial variation was linked to nematode trophic organization. Belowground recovery across these karst vegetation restoration systems was closely associated with soil habitat conditions, particularly soil moisture. Omnivore‐predators and SMFW metrics showed promise as indicators of restoration‐associated belowground recovery.