Microplastic fibres affect soil fungal communities depending on drought conditions with consequences for ecosystem functions

• Published in: Environmental microbiology 2024-02, Vol.26 (2), p.e16549-n/a
• Main Authors: Lozano, Y. M., Dueñas, J. F., Zordick, C., Rillig, M. C.
• Format: Article
• Language: English
• Subjects: Aggregation; Antagonism; Drought; Ecological function; Ecosystems; Factorial design; Fibers; Fineness; Fungi; Leaching; Microplastics; Moisture content; Pathogens; Plastic pollution; Porosity; Rhizosphere; Soil improvement; Soil microorganisms; Soil porosity; Soil properties; Soil water; Toxic substances
• ISSN: 1462-2912; 1462-2920
• DOI: 10.1111/1462-2920.16549

Microplastics affect soil functions depending on drought conditions. However, how their combined effect influences soil fungi and their linkages with ecosystem functions is still unknown. To address this, we used rhizosphere soil from a previous experiment in which we employed microplastic fibres addition and drought in a factorial design, and evaluated their effects on soil fungal communities. Microplastics decreased soil fungal richness under well‐watered conditions, likely linked to microplastics leaching toxic substances into the soil, and microplastic effects on root fineness. Under drought, by contrast, microplastics increased pathogen and total fungal richness, likely related to microplastic positive effects on soil properties, such as water holding capacity, porosity or aggregation. Soil fungal richness was the attribute most affected by microplastics and drought. Microplastics altered the relationships between soil fungi and ecosystem functions to the point that many of them flipped from positive to negative or disappeared. The combined effect of microplastics and drought on fungal richness mitigated their individual negative effect (antagonism), suggesting that changes in soil water conditions may alter the action mode of microplastics in soil. Microplastic leaching of harmful substances can be mitigated under drought, while the improvement of soil properties by microplastics may alleviate such drought conditions. In watered soils, leaching of microplastic toxic substances into the soil decreases fungal richness, while by contrast in droughted soils, microplastics ameliorate soil properties increasing fungal richness. Overall, the combined effect of microplastics and drought mitigated their individual negative effect on soil fungal richness. Likewise, microplastics flipped from positive to negative the relationships between soil fungi and ecosystem functions.