Szymon Jędrzejewski

Over the past two decades, pesticide use has increased globally, with over 91% of crops in the EU being treated. While pesticides improve crop yields, they also pose environmental risks. They can affect non-target plants by inhibiting germination, suppressing growth, and impairing photosynthesis. Pesticide drift, runoff, and soil contamination may expose wild plant communities to sublethal concentrations, potentially disrupting biodiversity and ecosystem stability. This study examined the effects of commonly used pesticides in European agriculture on non-target plant species. Six active ingredients—acetamiprid, pirimicarb, glyphosate, fluroxypyr, azoxystrobin, and tebuconazole—were tested individually and in mixtures at realistic field concentrations. Toxicity was assessed in Sinapis alba, Lepidium sativum, and Sorghum saccharatum. Results showed that fluroxypyr (a herbicide) was consistently the most phytotoxic compound. All tested pesticide mixtures produced stronger phytotoxic effects than their components. Among the three models used to predict mixture toxicity—additive, dominance, and multiplicative—the additive model most accurately reflected the observed responses, assuming that the total effect equals the sum of the effects of individual substances. However, the model did not fully explain the enhanced toxicity observed in certain combinations, suggesting potential synergistic interactions. These findings underscore the need for further research on the ecological impact of pesticide mixtures. Graphical Abstract

High-latitude regions store substantial amounts of soil organic matter (SOM). Icelandic volcanic soils have exceptional capabilities for SOM accumulation, but recent changes in land use can significantly impact it. Water-extractable organic matter (WEOM) represents a labile SOM pool and serves as a reliable index of SOM dynamics. We assessed the stable carbon (C), stable nitrogen (N), and WEOC (water-extractable organic carbon), as well as WETN (water-extractable total nitrogen), concentrations in soils under different land uses—semi-natural habitats (tundra and wetland) and human-managed areas (intensively and extensively grazed pasturelands and formerly and presently fertilized meadows)—in southeastern Iceland. The results suggest that human-managed sites contain more total C and N but less WEOM per unit of total C or N than semi-natural habitats, except for wetlands. Wetlands exhibited the highest WEOM content. Extensive pasturelands and fertilized meadows are becoming more common in local ecosystems, highlighting the direction of changes in Icelandic grasslands management.