Sand barrier microplastics alter plant–soil interactions in artificial sand-fixation areas by constraining plant nutrient utilization

Abstract

The continuous release of sand barrier microplastics (PLA-MPs) from polymer sand barriers during weathering in arid sandy areas poses potential ecological risks that are not yet well understood, particularly regarding their effects on vegetation growth and soil ecosystems in desert environments. This study used Agriophyllum squarrosum, a typical sand-fixing pioneer species, and soil from the Ulan Buh Desert as the research system to increase ecological relevance. This study systematically evaluated the concentration-dependent effects of PLA-MPs on the plant–soil system in an arid sand-fixation area using an integrated multi-indicator approach combined with PLS-SEM. Through pot experiments with different concentrations of PLA-MPs, combined with structural equation modeling, the effects on plant growth, physiological traits, soil nutrients, and enzyme activities were evaluated. The results indicate that PLA-MPs significantly inhibited plant biomass and physiological performance, while promoting the accumulation of soil carbon and nitrogen and altering their stoichiometric ratios. However, enhanced soil nutrient levels did not translate into plant growth benefits, reflecting constrained nutrient uptake and utilization. Overall, PLA-MPs exhibited dual effects in arid sandy areas, suppressing plant growth while increasing soil nutrient accumulation, suggesting potential ecological risks associated with polymer sand barriers in desertification control. These findings provide new insights into plant–soil responses to biodegradable microplastics in arid sand-fixation ecosystems and contribute to the ecological risk assessment of polymer-based restoration materials in desert environments.