Long-term green waste mulching drives soil fertility and arthropod community restructuring in a peri-urban plantation forest

Urban plantations generate abundant green waste, yet its potential for in-situ ecological recycling is often underutilized. Soil arthropods play a pivotal role in litter decomposition and nutrient cycling, yet the long-term impacts of green waste management on soil-arthropod interactions remain poorly understood. Accordingly, we conducted a five-year field experiment in a peri-urban plantation forest in Beijing to investigate the effects of no mulch (CK), green waste mixture mulch (GM), twig mulch (T), and leaf litter mulch (L) treatments on soil physicochemical properties and ground-dwelling arthropod communities. All mulching treatments significantly enhanced soil organic matter (SOM) and total nitrogen (TN), with GM treatment showing the greatest increase (34.50% for SOM). L treatment excelled in enriching available phosphorus (AP) and potassium (AK). NMDS revealed clear compositional differentiation among treatments (stress = 0.167). CK exhibited extreme single-taxon dominance (Entomobryidae: 72.03%), while mulching promoted multi-taxa coexistence, with GM achieving the highest Margalef richness index, Shannon diversity, and Pielou's evenness. RDA further revealed that soil nutrient gradients (SOM, TN, alkaline hydrolysable nitrogen [AHN], AP, AK) were the primary drivers of community assembly, with elevated pH in CK associated with Entomobryidae dominance, whereas mulch-induced nutrient enrichment positively correlated with richness and diversity. Functional group analysis showed divergent responses: predator and herbivore abundances positively correlated with soil nutrients, whereas detritivore and omnivore abundances negatively correlated with soil nutrients, potentially reflecting niche replacement or competitive interactions under altered resource conditions. This study demonstrates that long-term green waste mixture mulching simultaneously enhances soil fertility and arthropod community complexity through resource heterogeneity and niche complementarity, providing effective guidance for sustainable urban green waste management and soil amendment.