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Microplastic-induced alterations in growth and microecology of mulberry seedlings: Implications for sustainable forest–soil systems

Environmental Pollution 2025 2 citations ? Citation count from OpenAlex, updated daily. May differ slightly from the publisher's own count.
Huazhou Wu, Xiaoyan Sun, Xiaoyan Sun, Dezhao Lou, Fuping Lu, Tao Geng, Shuchang Wang

Summary

This study found that polyethylene and polylactic acid (PLA) microplastics have very different effects on mulberry tree growth and soil microbes. Polyethylene actually stimulated tree growth and boosted soil nitrogen-cycling bacteria, while PLA reduced plant biomass and disrupted soil fungal communities important for nutrient uptake. The contrasting results show that different types of microplastics can have opposite effects on plant-soil systems, complicating predictions about their environmental impact.

Polymers

This study investigated the ecotoxicological effects of polyethylene (PE) and polylactic acid (PLA) microplastics (MPs) on mulberry growth and soil-microbe interactions through controlled pot experiments (0.1 % and 1 % concentrations). PE exposure significantly increased mulberry height by 16 % (0.1 %) and 18 % (1 %) (p < 0.05), whereas PLA reduced total biomass by 12 % (0.1 %) and 66 % (1 %), highlighting polymer- and concentration-dependent responses. MPs differentially modulated soil biogeochemistry: PE decreased nitrate and ammonium nitrogen levels while enhancing nitrogen fixation (nifH) (from 0.9 × 10 to 6.1 × 10 copies/g) and denitrification (nirK) (from 1.0 × 10 to 1.9 × 10 copies/g) gene expression via Acidobacteriota enrichment, which was correlated with increased soil organic matter mobilisation and photosynthetic rates. PLA disrupted phosphorus cycling and destabilised structure of fungal communities critical for nutrient assimilation. Structural equation modelling identified direct microplastic-soil-plant linkages, with real-time polymerase chain reaction validating PE-driven suppression of nitrogen loss through microbial functional shifts. These findings illuminate the dual roles of microplastics as ecological stressors and modifiers, providing actionable insights for balancing agricultural productivity and soil health in MP-contaminated forest ecosystems.

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