Differential responses of soil micro-food web components to global change factors: A meta-analysis

• Meta-analysis reveals three distinct pathways regulating soil micro-food web under global change. • Heavy metals reduce total nematode abundance by 76.01 %, while acid rain stimulates it. • Soil acidification is a master variable restructuring the soil micro-food web. • Nematodes act as active regulators, not just passive indicators, of ecosystem stress. The soil micro-food web, comprising bacteria, fungi, and nematodes, is fundamental to ecosystem functioning, yet its responses to global change are complex and poorly synthesized. Based on a meta-analysis of 99 published studies, we evaluated the effects of four major stressor categories—soil contamination, climate change, atmospheric pollution, and biological invasions—on this network. Our results demonstrate that global change stressors influence the soil micro-food web through three distinct pathways: resource availability, environmental stress, and biotic interactions. Noteworthy findings include severe suppression of the nematode community under heavy metal exposure (-76.01 % in total abundance) and drought (-41.09 %), while significant increase under acid rain (41.75 %) and nitrogen (N) deposition (21.96 %). A key mechanism identified is that a change in microbial biomass needs to reach a critical level to alter the abundance of nematode trophic groups. These responses were further modulated by environmental context; mean annual precipitation (MAP) supported fungal channel resilience, whereas mean annual temperature (MAT) shaped bacterial channel vulnerability. Soil acidification was identified as a master variable driving community restructuring. By validating this tripartite pathway framework, our study offers a mechanistic basis for predicting soil ecosystem responses to global change and underscores that nematodes act not merely as passive indicators, but as active regulators and integrators of ecosystem stress.