Unravelling the combined effects of drought and microplastic on plants and soil communities and their legacy effects via plant-soil feedback

• Applicant: Sara Tomiolo, Ph.D.
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 565846157

Terrestrial ecosystems are exposed to unprecedented change due to known ecological stressors, e.g. climate-change induced drought, and novel stressors, e.g. microplastic (MP) contamination. While their individual effects of these stressors are studied, combined impacts are less understood. Filling this knowledge gap is crucial as both stressors affect soil structure, water content and microbial communities, and consequently plant performance. Use of mulching foils in agricultural activities has been recognized as a major source of microplastic contamination at multiple spatial scales. Once MP particles resulting from the fragmentation of mulching foils are incorporated into the soil, they decrease soil water content and soil aggregate stability- which can amplify the negative effects of drought on soil physical properties- and increase the proportion of microbial guilds beneficial to plant growth -which can amplify some beneficial effects of drought. However, it is not known if the positive effects will override the negative ones and what are the implications for plants. I will address this knowledge gap in a greenhouse experiment that disentangles the effects of drought and MP on soil physical properties and soil microbial communities and consequently plant performance. Plant-soil feedbacks, where plants influence soil microbes (attracting specialized pathogens and symbionts) which in turn affect plant performance, are crucial for populations and communities. However, the combined impact of drought and microplastics on this process remains largely unexplored. This study addresses this gap by investigating the multi-generational legacy effects of drought and microplastics on soil communities and plant performance (i.e., plant-soil feedback). Soil and annual plant species from the eastern-Mediterranean region will be used because 1) The frequency of extreme droughts is increasing, 2) use of mulching films in agriculture is widespread, 3) the region is a hot spot of biodiversity. The results of this project will shed light on the mechanisms underlying the combined impacts of drought and MP, and on the relative importance of these two stressors. The output of this project will be relevant for biodiversity and climate change research.

• DFG Programme: Research Grants
• International Connection: Czech Republic, Israel, Netherlands
• Cooperation Partners: Roey Angel, Ph.D.; Dr. Michal Gruntman, Ph.D.; Professor Dr. Wim van der Putten; Professorin Merav Seifan, Ph.D.