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[This corrects the article DOI: 10.1371/journal.pone.0195517.].

On behalf of the Organising Committee and the Editors of this volume, we are delighted to present the Proceedings of IV All-Russian Conference with International Participation “Diversity of Soils and Biota of Northern and Central Asia” “DSBNCA-2021”), which was held in Ulan-Ude, Russia, June 15-18, 2021. List of Chairman, Co-Chairmen, Scientific Committee, Scientific Secretariat and Organising Committee are available in this pdf.

Several plant-soil biota (PSB) studies were recently published in high profile journals that used the suspect “mixed soil sampling” methodology. To explore the extent to which mixing field samples (i.e. employing mixed soil sample designs) can generate erroneous conclusions, we used real data to parameterize a system for simulating results for experiments based independent vs. mixed soil samples per greenhouse container. We quantified the probability of type I statistical errors for each soil handling technique. We found that correct methods had predicted levels of type I statistical errors (ca. 5%). Incorrect methodology (mixed soil samples) had unacceptably high levels of type I statistical errors (ca. 50%). Our simulation highlights how robust PSB experiments require proper soil handling technique.

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment.

Analysis of modern animals and Ediacaran trace fossils predicts that the oldest bilaterians were simple and small. Such organisms would be difficult to recognize in the fossil record, but should have been part of the Ediacara Biota, the earliest preserved macroscopic, complex animal communities. Here, we describe Ikaria wariootia gen. et sp. nov. from the Ediacara Member, South Australia, a small, simple organism with anterior/posterior differentiation. We find that the size and morphology of Ikaria match predictions for the progenitor of the trace fossil Helminthoidichnites—indicative of mobility and sediment displacement. In the Ediacara Member, Helminthoidichnites occurs stratigraphically below classic Ediacara body fossils. Together, these suggest that Ikaria represents one of the oldest total group bilaterians identified from South Australia, with little deviation from the characters predicted for their last common ancestor. Further, these trace fossils persist into the Phanerozoic, providing a critical link between Ediacaran and Cambrian animals.

New information on the lethal and sublethal effects of neonicotinoids and fipronil on organisms is presented in this review, complementing the previous Worldwide Integrated Assessment (WIA) in 2015. The high toxicity of these systemic insecticides to invertebrates has been confirmed and expanded to include more species and compounds. Most of the recent research has focused on bees and the sublethal and ecological impacts these insecticides have on pollinators. Toxic effects on other invertebrate taxa also covered predatory and parasitoid natural enemies and aquatic arthropods. Little new information has been gathered on soil organisms. The impact on marine and coastal ecosystems is still largely uncharted. The chronic lethality of neonicotinoids to insects and crustaceans, and the strengthened evidence that these chemicals also impair the immune system and reproduction, highlights the dangers of this particular insecticidal class (neonicotinoids and fipronil), with the potential to greatly decrease populations of arthropods in both terrestrial and aquatic environments. Sublethal effects on fish, reptiles, frogs, birds, and mammals are also reported, showing a better understanding of the mechanisms of toxicity of these insecticides in vertebrates and their deleterious impacts on growth, reproduction, and neurobehaviour of most of the species tested. This review concludes with a summary of impacts on the ecosystem services and functioning, particularly on pollination, soil biota, and aquatic invertebrate communities, thus reinforcing the previous WIA conclusions (van der Sluijs et al. 2015 ).

A census of the biomass on Earth is key for understanding the structure and dynamics of the biosphere. However, a global, quantitative view of how the biomass of different taxa compare with one another is still lacking. Here, we assemble the overall biomass composition of the biosphere, establishing a census of the ≈550 gigatons of carbon (Gt C) of biomass distributed among all of the kingdoms of life. We find that the kingdoms of life concentrate at different locations on the planet; plants (≈450 Gt C, the dominant kingdom) are primarily terrestrial, whereas animals (≈2 Gt C) are mainly marine, and bacteria (≈70 Gt C) and archaea (≈7 Gt C) are predominantly located in deep subsurface environments. We show that terrestrial biomass is about two orders of magnitude higher than marine biomass and estimate a total of ≈6 Gt C of marine biota, doubling the previous estimated quantity. Our analysis reveals that the global marine biomass pyramid contains more consumers than producers, thus increasing the scope of previous observations on inverse food pyramids. Finally, we highlight that the mass of humans is an order of magnitude higher than that of all wild mammals combined and report the historical impact of humanity on the global biomass of prominent taxa, including mammals, fish, and plants.

Microplastic effects in terrestrial ecosystems have recently moved into focus, after about a decade of research being limited to aquatic systems. While effects on soil physical properties and soil biota are starting to become apparent, there is not much information on the consequences for plant performance. We here propose and discuss mechanistic pathways through which microplastics could impact plant growth, either positively or negatively. These effects will vary as a function of plant species, and plastic type, and thus are likely to translate to changes in plant community composition and perhaps primary production. Our mechanistic framework serves to guide ongoing and future research on this important topic.

Plant–soil feedback (PSF) occurs when plants alter soil properties that influence the performance of seedlings, with consequent effects on plant populations and communities. Many processes influence PSF, including changes in nutrient availability and the accumulation of natural enemies, mutualists or secondary chemicals. Typically, these mechanisms are investigated in isolation, yet no single mechanism is likely to be completely responsible for PSF as these processes can interact. Further, the outcome depends on which resources are limiting and the other plants and soil biota in the surrounding environment. As such, understanding the mechanisms of PSF and their role within plant communities requires quantification of the interactions among the processes influencing PSF and the associated abiotic and biotic contexts.

Soil biota influence plant performance through plant-soil feedback, but it is unclear whether the strength of such feedback depends on plant traits and whether plant-soil feedback drives local plant diversity. We grew 16 co-occurring plant species with contrasting nutrient-acquisition strategies from hyperdiverse Australian shrublands and exposed them to soil biota from under their own or other plant species. Plant responses to soil biota varied according to their nutrient-acquisition strategy, including positive feedback for ectomycorrhizal plants and negative feedback for nitrogen-fixing and nonmycorrhizal plants. Simulations revealed that such strategy-dependent feedback is sufficient to maintain the high taxonomic and functional diversity characterizing these Mediterranean-climate shrublands. Our study identifies nutrient-acquisition strategy as a key trait explaining how different plant responses to soil biota promote local plant diversity.