Effects of Microplastics and Drought on Ecosystem Functions and Multifunctionality

Abstract

Microplastics in soils have become an important threat for terrestrial systems, which can be exacerbated by drought as microplastics may affect soil water content. Thus, the interaction between these two factors may alter ecosystem functions such as litter decomposition, stability of soil aggregates, as well as functions related to nutrient cycling. Despite this potential interaction, we know relatively little about how microplastics, under different soil water conditions, affect ecosystem functions and ecosystem multifunctionality.To address this gap, we carried out a controlled-environment study using grassland plant communities. We applied the two factors microplastic fibers (absent, present) and soil water conditions (well-watered, drought), in all possible combinations in a factorial experiment. At harvest, we measured multiple ecosystem functions linked to nutrient cycling, litter decomposition, and soil aggregation and as terrestrial systems provide these functions simultaneously, we also assessed ecosystem multifunctionality.Our results showed that the interaction between microplastic fibers and drought affected ecosystem functions and multifunctionality. Overall, drought had negatively affected nutrient cycling by decreasing potential enzymatic activities and increasing nutrient leaching, while microplastic fibers had a positive impact on soil aggregation and nutrient retention by diminishing nutrient leaching. Microplastic fibers also impacted enzymatic activities, soil respiration and ecosystem multifunctionality, but importantly, the direction of these effects depended on soil water status (i.e., they decreased under well watered conditions, but tended to increase or had similar effects under drought conditions). Litter decomposition had a contrary pattern.Synthesis and applications. As soil water content is affected by climate change, our results suggest that areas with sufficiency of water would be negatively affected in their ecosystem functioning as microplastics increase in the soil; however, in areas subjected to drought, microplastics would have a neutral or slightly positive effect on ecosystem functioning.

Microplastic Shape, Polymer Type, and Concentration Affect Soil Properties and Plant Biomass

“…Finally, as microplastics are ubiquitous around the globe, any effects of microplastics on plant-soil systems would have consequences not only in grasslands but also in different ecosystems worldwide. For instance, drylands, one of the largest terrestrial biomes that cover 41% of Earth’s land surface and that supports over 38% of the global human population ( Reynolds et al, 2007 ), characterized by its water scarcity, can be highly threatened with an increasing of microplastic concentration in the soil, especially as microplastics can exacerbate the negative effects that other global change factors as drought have on plant communities ( Lozano et al, 2020 ), soil properties, and ecosystem multifunctionality ( Lozano et al, 2021 ). This in turn may affect ecosystem services ( Díaz et al, 2018 ; Manning et al, 2018 ) and thus impact various aspects of human well-being.…”

Effects of microplastics and drought on soil ecosystem functions and multifunctionality

“…Data available via the Dryad Digital Repository https://doi.org/10.5061/dryad.nvx0k6drc (Lozano, Aguilar‐Trigueros, et al., 2021).…”

“…analysed the data and wrote the first draft of this manuscript. All authors contributed to the final version and gave final approval for publication.DATA AVA I L A B I L I T Y S TAT E M E N TData available via the Dryad Digital Repository https://doi.org/10.5061/ dryad.nvx0k 6drc(Lozano, Aguilar-Trigueros, et al, 2021). .…”