scholarly journals Microplastics negatively affect soil fauna but stimulate microbial activity: insights from a field-based microplastic addition experiment

2020 ◽  
Vol 287 (1934) ◽  
pp. 20201268 ◽  
Author(s):  
Dunmei Lin ◽  
Guangrong Yang ◽  
Pengpeng Dou ◽  
Shenhua Qian ◽  
Liang Zhao ◽  
...  
Keyword(s):  
Food Webs ◽  
Structural Equation ◽  
Soil Fauna ◽  
Soil Microbial Communities ◽  
Ecological Impacts ◽  
Trophic Levels ◽  
Soil Community ◽  
Soil Microbial ◽  
Soil Food Webs ◽  
Manipulation Experiment

Microplastics are recognized as an emerging contaminant worldwide. Although microplastics have been shown to strongly affect organisms in aquatic environments, less is known about whether and how microplastics can affect different taxa within a soil community, and it is unclear whether these effects can cascade through soil food webs. By conducting a microplastic manipulation experiment, i.e. adding low-density polyethylene fragments in the field, we found that microplastic addition significantly affected the composition and abundance of microarthropod and nematode communities. Contrary to soil fauna, we found only small effects of microplastics on the biomass and structure of soil microbial communities. Nevertheless, structural equation modelling revealed that the effects of microplastics strongly cascade through the soil food webs, leading to the modification of microbial functioning with further potential consequences on soil carbon and nutrient cycling. Our results highlight that taking into account the effects of microplastics at different trophic levels is important to elucidate the mechanisms underlying the ecological impacts of microplastic pollution on soil functioning.

scholarly journals Cessation of grazing causes biodiversity loss and homogenization of soil food webs

2021 ◽  
Author(s):  
Maarten Schrama ◽  
Casper Quist ◽  
Arjen De Groot ◽  
Ellen Cieraad ◽  
deborah ashworth ◽  
...  
Keyword(s):  
Food Webs ◽  
Soil Fauna ◽  
Soil Microbial Communities ◽  
Biodiversity Loss ◽  
Soil Organisms ◽  
Soil Microbial ◽  
Soil Food Webs ◽  
Β Diversity ◽  
The United Kingdom ◽  
Faunal Diversity

There is widespread concern that cessation of grazing in historically grazed ecosystems is causing biotic homogenization and biodiversity loss. Here, we used 12 montane grassland sites along an 800-km north-south gradient across the United Kingdom, to test whether cessation of grazing affects local ɑ- and β-diversity of belowground food webs. We show that cessation of grazing leads to strongly decreased ɑ-diversity of both soil microbial and faunal diversity. In contrast, the β-diversity varied between groups of soil organisms. While soil microbial communities exhibited increased homogenization after cessation of grazing, we observed decreased homogenization for soil fauna after cessation of grazing. Overall, our results indicate that grazer exclusion from historically grazed montane grasslands has far-ranging consequences for the diversity and composition of belowground food webs, and underscore the importance of grazers for maintaining the diversity of belowground communities, which play a central role in ecosystem functioning.

Using structural equation modeling to test established theory and develop novel hypotheses for the structuring forces in soil food webs

Pedobiologia ◽  
2015 ◽  
Vol 58 (4) ◽  
pp. 137-145 ◽  
Author(s):  
Yuanhu Shao ◽  
Weikai Bao ◽  
Dima Chen ◽  
Nico Eisenhauer ◽  
Weixin Zhang ◽  
...  
Keyword(s):  
Structural Equation Modeling ◽  
Food Webs ◽  
Structural Equation ◽  
Equation Modeling ◽  
Soil Food Webs

scholarly journals Radiocarbon signature reveals that most springtails depend on carbon from living plants

2021 ◽  
Vol 17 (9) ◽  
pp. 20210353
Author(s):  
Saori Fujii ◽  
Takashi F. Haraguchi ◽  
Ichiro Tayasu
Keyword(s):  
Food Webs ◽  
Carbon Cycling ◽  
Feeding Habits ◽  
Significant Negative Correlation ◽  
Trophic Levels ◽  
Soil Microarthropods ◽  
Soil Food Webs ◽  
Animal Feeding ◽  
Taxonomic Groups ◽  
Isotope Analyses

Terrestrial carbon cycling is largely mediated by soil food webs. Identifying the carbon source for soil animals has been desired to distinguish their roles in carbon cycling, but it is challenging for small invertebrates at low trophic levels because of methodological limitations. Here, we combined radiocarbon ( 14 C) analysis with stable isotope analyses ( 13 C and 15 N) to understand feeding habits of soil microarthropods, especially focusing on springtail (Collembola). Most Collembola species exhibited lower Δ 14 C values than litter regardless of their δ 13 C and δ 15 N signatures, indicating their dependence on young carbon. In contrast with general patterns across all taxonomic groups, we found a significant negative correlation between δ 15 N and Δ 14 C values among the edaphic Collembola. This means that the species with higher δ 15 N values depend on C from more recent photosynthate, which suggests that soil-dwelling species generally feed on mycorrhizae to obtain root-derived C. Many predatory taxa exhibited higher Δ 14 C values than Collembola but lower than litter, indicating non-negligible effects of collembolan feeding habits on the soil food web. Our study demonstrated the usefulness of radiocarbon analysis, which can untangle the confounding factors that change collembolan δ 15 N values, clarify animal feeding habits and define the roles of organisms in soil food webs.

scholarly journals Cascading Effects of Moth Outbreaks on Subarctic Soil Food Webs

2021 ◽  
Author(s):  
Irene Calderón-Sanou ◽  
Tamara Münkemüller ◽  
Lucie Zinger ◽  
Heidy Schimann ◽  
Nigel Gilles Yoccoz ◽  
...  
Keyword(s):  
Food Webs ◽  
Large Scale ◽  
Trophic Levels ◽  
Trophic Groups ◽  
Holistic View ◽  
Cascading Effects ◽  
Soil Food Webs ◽  
Network Analyses ◽  
Northern Fennoscandia ◽  
Belowground Diversity

Abstract The increasing severity and frequency of natural disturbances requires a better understanding of their effects on all compartments of biodiversity. In Northern Fennoscandia, recent large-scale moth outbreaks have led to an abrupt change in plant communities from birch forests dominated by dwarf shrubs to grass-dominated systems. However, the indirect effects on the belowground compartment remained unclear. Here, we combined eDNA survey of multiple trophic groups with network analyses to demonstrate that moth defoliation has far-reaching consequences on soil food webs. Following this disturbance, diversity and relative abundance of certain trophic groups declined (e.g. ectomycorrhizal fungi) while many others profited (e.g. bacterivores, omnivores) making soil food webs more diverse and structurally different. Overall, the direct and indirect consequences of moth outbreaks increased belowground diversity at different trophic levels. Our results highlight that a holistic view of ecosystems improves our understanding of cascading effects of major disturbances on soil food webs.

Free-living nematodes as prey for higher trophic levels of forest soil food webs

Oikos ◽  
2014 ◽  
Vol 123 (10) ◽  
pp. 1199-1211 ◽  
Author(s):  
Kerstin Heidemann ◽  
Annika Hennies ◽  
Johanna Schakowske ◽  
Lars Blumenberg ◽  
Liliane Ruess ◽  
...  
Keyword(s):  
Food Webs ◽  
Forest Soil ◽  
Trophic Levels ◽  
Free Living ◽  
Soil Food Webs

scholarly journals Methane-derived carbon flows into host–virus networks at different trophic levels in soil

2021 ◽  
Vol 118 (32) ◽  
pp. e2105124118
Author(s):  
Sungeun Lee ◽  
Ella T. Sieradzki ◽  
Alexa M. Nicolas ◽  
Robin L. Walker ◽  
Mary K. Firestone ◽  
...  
Keyword(s):  
Microbial Communities ◽  
Soil Microbial Communities ◽  
Stable Isotope Probing ◽  
Trophic Levels ◽  
Methylotrophic Bacteria ◽  
Metagenomic Sequencing ◽  
Atmospheric Methane ◽  
Diverse Range ◽  
Soil Microbial ◽  
Predatory Bacteria

The concentration of atmospheric methane (CH4) continues to increase with microbial communities controlling soil–atmosphere fluxes. While there is substantial knowledge of the diversity and function of prokaryotes regulating CH4 production and consumption, their active interactions with viruses in soil have not been identified. Metagenomic sequencing of soil microbial communities enables identification of linkages between viruses and hosts. However, this does not determine if these represent current or historical interactions nor whether a virus or host are active. In this study, we identified active interactions between individual host and virus populations in situ by following the transfer of assimilated carbon. Using DNA stable-isotope probing combined with metagenomic analyses, we characterized CH4-fueled microbial networks in acidic and neutral pH soils, specifically primary and secondary utilizers, together with the recent transfer of CH4-derived carbon to viruses. A total of 63% of viral contigs from replicated soil incubations contained homologs of genes present in known methylotrophic bacteria. Genomic sequences of 13C-enriched viruses were represented in over one-third of spacers in CRISPR arrays of multiple closely related Methylocystis populations and revealed differences in their history of viral interaction. Viruses infecting nonmethanotrophic methylotrophs and heterotrophic predatory bacteria were also identified through the analysis of shared homologous genes, demonstrating that carbon is transferred to a diverse range of viruses associated with CH4-fueled microbial food networks.

scholarly journals The soil microbial food web revisited: Predatory myxobacteria as keystone taxa?

2021 ◽  
Author(s):  
Sebastian Petters ◽  
Verena Groß ◽  
Andrea Söllinger ◽  
Michelle Pichler ◽  
Anne Reinhard ◽  
...  
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Microbial Food Web ◽  
Organic Soils ◽  
Ssu Rrna ◽  
Soil Microbial ◽  
Soil Food Webs ◽  
Community Profiling ◽  
Predatory Bacteria ◽  
Mineral Soils

AbstractTrophic interactions are crucial for carbon cycling in food webs. Traditionally, eukaryotic micropredators are considered the major micropredators of bacteria in soils, although bacteria like myxobacteria and Bdellovibrio are also known bacterivores. Until recently, it was impossible to assess the abundance of prokaryotes and eukaryotes in soil food webs simultaneously. Using metatranscriptomic three-domain community profiling we identified pro- and eukaryotic micropredators in 11 European mineral and organic soils from different climes. Myxobacteria comprised 1.5–9.7% of all obtained SSU rRNA transcripts and more than 60% of all identified potential bacterivores in most soils. The name-giving and well-characterized predatory bacteria affiliated with the Myxococcaceae were barely present, while Haliangiaceae and Polyangiaceae dominated. In predation assays, representatives of the latter showed prey spectra as broad as the Myxococcaceae. 18S rRNA transcripts from eukaryotic micropredators, like amoeba and nematodes, were generally less abundant than myxobacterial 16S rRNA transcripts, especially in mineral soils. Although SSU rRNA does not directly reflect organismic abundance, our findings indicate that myxobacteria could be keystone taxa in the soil microbial food web, with potential impact on prokaryotic community composition. Further, they suggest an overlooked, yet ecologically relevant food web module, independent of eukaryotic micropredators and subject to separate environmental and evolutionary pressures.

scholarly journals Meta-analysis of the impact of plant invasions on soil microbial communities

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nardi Torres ◽  
Ileana Herrera ◽  
Laurie Fajardo ◽  
Ramiro O. Bustamante
Keyword(s):  
Microbial Community ◽  
Bacterial Diversity ◽  
Invasive Plants ◽  
Soil Microbial Community ◽  
Meta Analysis ◽  
Soil Microbial Communities ◽  
Plant Invasions ◽  
Ecological Impacts ◽  
Soil Biota ◽  
Soil Microbial

Abstract Background One of the ecological impacts of exotic plant invasions may be alteration of the soil microbial community, which may cause changes to the diversity, richness and function of these communities. In order to explore to what extent invasive plants affect the soil microbial community, we performed a meta-analysis based on 46 scientific articles to document the effect of invasive plants on species richness and diversity of bacteria and fungi. We conducted our study across a range of invaded ecosystems including native communities, and evaluated biomass, richness and diversity. We use a random effects model to determine the increase or decrease in the values of the response variables in the presence of invasive plants. Results The results indicated that the response variable that changed with the invasion of plants was the diversity of bacteria. Bacterial diversity in the soil increases with the presence of invasive plants, specifically herbaceous plants producing allelopathic substances growing in forest ecosystems of temperate zones. Conclusions We provide evidence that invasive plants affect the soil biota differentially; however, it is important to consider more variables such as the N and C cycles, since these processes are mediated by soil biota and litter, and chemical compounds released by plants influence them. Changes in bacterial diversity have consequences for the nutrient cycle, enzymatic activity, mineralization rates and soil carbon and nitrogen content.

scholarly journals Diverse soil RNA viral communities have the potential to influence grassland ecosystems across multiple trophic levels

2021 ◽  
Author(s):  
Luke S. Hillary ◽  
Evelien M. Adriaenssens ◽  
David L. Jones ◽  
James E McDonald
Keyword(s):  
Phylogenetic Analyses ◽  
Soil Microbial Communities ◽  
Terrestrial Ecosystems ◽  
Trophic Levels ◽  
Soil Dna ◽  
Holistic View ◽  
Soil Microbial ◽  
Grassland Ecosystems ◽  
Viral Communities ◽  
Coastal Soils

Grassland ecosystems form 30-40% of total land cover and provide essential ecosystem services, including food production, flood mitigation and carbon storage. Their productivity is closely related to soil microbial communities, yet the role of viruses within these critical ecosystems is currently undercharacterised and in particular, our knowledge of soil RNA viruses is significantly limited. Here, we applied viromics to characterise soil RNA viral communities along an altitudinal productivity gradient of peat, managed grassland and coastal soils. We identified 3,462 viral operational taxonomic units (vOTUs) and assessed their spatial distribution, phylogenetic diversity and potential host ranges. Soil types exhibited showed minimal similarity in viral community composition, but with >10-fold more vOTUs shared between managed grassland soils when compared with peat or coastal soils. Phylogenetic analyses of viral sequences predicted broad host ranges including bacteria, plants, fungi, vertebrates and invertebrates, contrasting with soil DNA viromes which are typically dominated by bacteriophages. RNA viral communities therefore likely have the ability to influence soil ecosystems across multiple trophic levels. Our study represents an important step towards the characterisation of terrestrial RNA viral communities and the intricate interactions with their hosts, which will provide a more holistic view of the biology of economically and ecologically important terrestrial ecosystems.

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