Polypropylene and Polylactic Acid Microplastics Alter Plateau Wetland Seed Bank Emergence and Community Assembly: A Greenhouse Stress Test Experiment

Microplastic contamination has emerged as a growing concern for soil ecosystems and their ecological functioning. However, the effects of microplastic contamination in fragile plateau wetlands remain poorly understood. In this study, biodegradable polylactic acid (PLA) and conventional polypropylene (PP) MPs were compared using soil seed bank collected from terrestrial and hygrophytic habitats in the Xingyun Lake plateau wetland. Seed germination, species diversity, and soil chemical properties were evaluated. Habitat specific effects were observed, and PLA induced stronger inhibition of seed germination and diversity than PP. These findings underscore the need to incorporate plant ecological responses, including germination physiology under chemical stress and soil seed bank dynamics, into ecological risk assessments of MPs. Furthermore, MP associated changes in nutrient dynamics and soil chemistry were examined, providing insight into potential long-term implications for plateau wetland restoration and plant community recovery.