Microplastic pollution decouples soil food web structure-function cascades in plastic-mulched arid agroecosystems: Northwest China as a global testbed.

Arid and semi-arid agroecosystems cover nearly half of global croplands and face escalating threats from microplastic (MP) pollution. Current empirical research has predominantly focused on MP toxic effects on individual soil microbial groups. However, few systematic investigations have addressed multitrophic responses of soil food webs or developed an integrated mechanistic framework to synthesize such trophic changes. Herein, we establish a holistic soil food web-centred framework to disentangle MP-induced ecological alterations specific to arid and semi-arid agroecosystems. A core novelty of our framework lies in identifying soil food web energy flux as a potential underappreciated mediator linking biodiversity to ecosystem functioning (BEF) under MPs pollution. We further delineate major outstanding knowledge gaps: the context dependence of MPs effects, the scarcity of food web-scale empirical evidence, the mediating role of energy flux, potential interactive effects with other chemical stressors, and the absence of evidence-based restoration strategies. Addressing these bottlenecks demands a paradigm shift from single species toxicology to multifactorial, food web level research. Taking plastic-mulched agroecosystems across Northwest China as a global testbed, this study constructs a testable conceptual framework to elaborate context-specific cascading mechanisms of microplastic pollution unique to drylands. Our synthesized framework provides targeted theoretical guidance for mitigating MP-triggered soil food web degradation and sustaining the long-term sustainability of arid agroecosystems worldwide.