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Adding additives (e.g., carbon dots, CDs) to liquid lubricants is an effective method for enhancing their load‐bearing capacity and friction reduction. However, it is challenging to simultaneously impart high load‐bearing capacity and superlubricity for them (e.g., ionic liquid analogs, ILAs) through this strategy due to strong Coulombic interactions. With CDs as a competing ligand operon, the cluster size distribution can be expanded, conferring superlubricity with ultrahigh load‐bearing capacity (>705 MPa, the highest value of CDs‐based superlubricious materials thus far) for CDs/ILAs. In particular, methodologies such as Raman, 1H‐NMR, fourier transform infrared spectroscopy, and laser particle size analysis are employed to characterize the evolution of their H‐bonding interactions and particle size distribution. CDs can act as competing ligands and enable CDs/ILAs to form systems with ultra‐low coefficient of friction and wear consisting of a mixture of large and small clusters. The mixed and expanded size clusters facilitate the reduction of the viscosity for CDs/ILAs under shear, thereby reducing the interfacial shear resistance during superlubricity, while the CDs within them efficiently transfer the normal bearing loads. The progress is made from the perspective of cluster particle size distribution rather than individual additive properties, providing a new avenue for designing ILAs‐based superlubricious materials. [ABSTRACT FROM AUTHOR]

Soil salinization is a serious problem leading to ecological degradation. Melia azedarach is highly salt‐tolerant, and its application to saline‐alkali land is a promising strategy for restoring degraded lands. However, most studies only focus on the salt‐reducing effect of herbs on saline‐alkali land, and there are few studies on the metabolic adaptation mechanism of trees in the process of soil restoration in coastal saline‐alkali land. In this study, we analyzed the soil properties and metabolome of M. azedarach roots grown in low‐ (<3 g/kg; L), medium‐ (5 ~ 8 g/kg; M), and high‐ (>10 g/kg; H) salinity soils to explore the amelioration effect and adaptation mechanism of M. azedarach to soils with differential salinity. Cultivation of M. azedarach was associated with a decrease in the concentration of Na+ and increases in organic matter content and alkaline phosphatase and urease activities in the rhizosphere soil. The metabolome analysis revealed that a total of 382 (ESI+) and 277 (ESI−) differential metabolites (DEMs) were detected. The number of DEMs in roots rose with increased soil salinity, such as sugars and flavonoids in H versus L, and amino acids in M versus L. The most up‐regulated DEMs were 13‐S‐hydroxyoctadecadienoic acid, 2′‐Deoxyuridine, and 20‐hydroxyleukotriene B4. Combined analysis of soil properties and M. azedarach DEMs indicated that alkaline phosphatase activity was positively correlated with traumatic acid concentration. Taken together, these results indicate that M. azedarach has the potential to reduce soil salinity and enhance soil enzyme activity, and it can adapt to salt stress by regulating metabolites like sugars, amino acids, and flavonoids. This study provides a basis for understanding the mechanism underlying the adaptation of M. azedarach to saline‐alkali soil and its amelioration. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Applied Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Applied Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Anthropogenic land use is threatening global biodiversity. As one of the most abundant animals on Earth, nematodes occupy several key positions in belowground food webs and contribute to many ecosystem functions and services. However, the effects of land use on nematode abundance and its determinants remain poorly understood at a global scale.To characterize nematodes' responses to land use across trophic groups, we used a dataset of 6,825 soil samples globally to assess how nematode abundance varies among regional land‐use types (i.e. primary vegetation, secondary vegetation, pasture, cropland and urban) and local land‐use intensities (i.e. human‐managed or not). We also quantified the interactive effects of land use and environmental predictors (i.e. mean annual temperature, annual precipitation, soil organic carbon, soil pH, global vegetation biomass and global vegetation productivity) on nematode abundance.We found that total nematode abundance and the abundance of bacterivores, fungivores, herbivores, omnivores and predators generally increased or were not affected under management across land‐use types. Specifically, the most numerically abundant bacterivores were higher in managed than in unmanaged secondary vegetation habitats and urban areas, and herbivores were more abundant in managed than in unmanaged primary and secondary vegetation habitats. Furthermore, the numbers of significant environmental predictors of nematode abundance were reduced and the magnitude and the direction of the predictors were changed under management. We also found that nematode abundance was more variable and less determined by environmental factors in urban than in other land‐use types.These findings challenge the view that human land use decreases animal abundance across trophic groups, but highlight that land use is altering the trophic composition of soil nematodes and its relationships with the environment at the global scale. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Ecology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Both contemporary and historical factors are documented to be crucial in regulating species diversity and distribution. Soil fauna contribute substantially to global biodiversity and ecosystem functioning, while it is unclear whether and to what extent historical factors shape their diversity patterns. Here, we used soil nematodes as a model organism to test historical effects on soil fauna and to investigate the relative importance of climatic, soil, and historical factors. Based on nematode distribution data in 16 natural sites at a large scale (ranging from 22 to 40°N) in mainland China, we conducted elastic net regression model to test the effects of climatic (e.g., mean and seasonality of temperature/precipitation), soil (e.g., soil carbon, nitrogen, and pH), and historical (e.g., temperature/precipitation anomaly and the velocity of the change since the Last Glacial Maximum) variables on nematode genus richness and Shannon's diversity. Additionally, variation partitioning was used to determine the contribution of the three predictor sets to the explanation of both Jaccard and Bray–Curtis community dissimilarity. We found that climate generally explained more variations in both diversity and composition than soil and historical predictors in our samples. We also showed that although historical factors (e.g., temperature change velocity) were correlated with nematode diversity and composition, the pure effects of these historical factors were negligible. In other words, the historical effects were commonly represented by their interactions with current climatic and soil factors within our selected sites. Our results indicated that contemporary factors, especially climate, may outperform historical factors in regulating soil nematode diversity patterns at large scales. [ABSTRACT FROM AUTHOR]

Summary: Soil organic carbon (SOC) sequestration under elevated CO2 concentration (eCO2) is a function of carbon (C) input and C retention. Nitrogen (N) limitation in natural ecosystems can constrain plant responses to eCO2 and their subsequent effects on SOC, but the effect of eCO2 on SOC in N‐enriched agroecosystems with cultivars highly responsive to eCO2 is largely unknown.We reported results of SOC dynamics from a field free‐air CO2 enrichment experiment with two rice cultivars having distinct photosynthetic capacities under eCO2. A reciprocal incubation experiment was further conducted to disentangle the effect of changes in litter quality and soil microbial community on litter‐derived C dynamics.eCO2 significantly increased total SOC content, dissolved organic C and particulate organic C under the strongly responsive cultivar, likely due to enhanced organic C inputs originated from CO2 stimulation of shoot and root biomass. Increases in the residue C : N ratio and fungal abundance induced by eCO2 under the strongly responsive cultivar reduced C losses from decomposition, possibly through increasing microbial C use efficiency.Our findings suggest that applications of high‐yielding cultivars may substantially enhance soil C sequestration in rice paddies under future CO2 scenarios. [ABSTRACT FROM AUTHOR]

Anthropogenic conversion of natural to agricultural land reduces aboveground biodiversity. Yet, the overall consequences of land‐use changes on belowground biodiversity at large scales remain insufficiently explored. Furthermore, the effects of conversion on different organism groups are usually determined at the taxonomic level, while an integrated investigation that includes functional and phylogenetic levels is rare and absent for belowground organisms. Here, we studied the Earth's most abundant metazoa—nematodes—to examine the effects of conversion from natural to agricultural habitats on soil biodiversity across a large spatial scale. To this aim, we investigated the diversity and composition of nematode communities at the taxonomic, functional, and phylogenetic level in 16 assemblage pairs (32 sites in total with 16 in each habitat type) in mainland China. While the overall alpha and beta diversity did not differ between natural and agricultural systems, all three alpha diversity facets decreased with latitude in natural habitats. Both alpha and beta diversity levels were driven by climatic differences in natural habitats, while none of the diversity levels changed in agricultural systems. This indicates that land conversion affects soil biodiversity in a geographically dependent manner and that agriculture could erase climatic constraints on soil biodiversity at such a scale. Additionally, the functional composition of nematode communities was more dissimilar in agricultural than in natural habitats, while the phylogenetic composition was more similar, indicating that changes among different biodiversity facets are asynchronous. Our study deepens the understanding of land‐use effects on soil nematode diversity across large spatial scales. Moreover, the detected asynchrony of taxonomic, functional, and phylogenetic diversity highlights the necessity to monitor multiple facets of soil biodiversity in ecological studies such as those investigating environmental changes. [ABSTRACT FROM AUTHOR]

Long‐term chemical‐only fertilisation (NPK) decreases soil pH, but this soil acidification is rarely reported with manure fertilisation (M). Soil acidification always leads to a negative effect on sustainable development. As oxalate oxidation is accompanied by soil alkalisation, it is still unknown how and to what extent bacterial oxalate oxidation in soils with different fertilisation regimes contributes to buffering of soil acidification. To assess the potential role of oxalotrophy in buffering soil acidification, two soils that underwent contrasted fertilisation regimes for over 30 years were used. The oxalotrophic communities were characterised based on a biomarker of oxalotrophic taxa (the frc gene), and their responsiveness to calcium oxalate (CaOx) addition was assessed. In addition, stable isotope probing was employed to explore the active bacteria responding to CaOx addition. Despite similar abundances of oxalotrophic bacteria between NPK and M soils before microcosm incubation, the M soil harboured more oxalotrophic bacteria belonging to Deltaproteobacteria, and the NPK soil was colonised by more oxalotrophic bacteria affiliated with Actinobacteria, Alphaproteobacteria, and Betaproteobacteria. In the incubation experiments, the M soil took half of the time that the NPK soil needed to deplete the added CaOx. The faster CaOx consumption rate could be explained by the higher functional redundancy and higher proportion of fast‐response oxalotrophic taxa in M soil. The most dominant active oxalotrophic taxa were Oxalicibacterium and Burkholderia in the M and NPK soils, respectively. Furthermore, the better performance of oxalate oxidation was conjectured to contribute to a higher soil acidification buffering ability. This study obtained an important cue to the feasibility of active oxalotrophic taxa in buffering acidification in soils with different fertilisation regimes, which provides valuable evidence for exploring alternative ways for alleviating soil acidification. [ABSTRACT FROM AUTHOR]

Abstract: An increasing number of studies indicate that microbial diversity plays a crucial role in the mediation of ecosystem multifunctionality (EMF) in natural ecosystems. However, this point remains mostly overlooked in managed ecosystems, especially in agriculture. Here, we compiled promising strategies for the targeted exploitation of the associations between microbial diversity and EMF of agricultural soils using samples from two long‐term (more than 30 years) experimental field sites in southern China. The two sites experienced a similar monsoon climate and fertilization management practices. We used high‐throughput amplicon sequencing, structural equation modelling and random forest analysis, to analyse our data and validate our hypotheses. We found that soil physiochemical properties and the C‐, N‐, P‐ and S‐cycle enzyme activities were increased with the increase in microbial diversity. Specifically, a positive linear relationship was observed between microbial diversity and EMF, which was mediated by long‐term fertilization management via changes in soil microbial communities and physiochemical properties. Random forest analysis and SEM showed that the important role of microbial diversity on EMF was maintained even when simultaneously taking multiple multifunctionality drivers (soil physiochemical properties, soil aggregation and enzymatic patterns) into account. In addition, microbial diversity, C‐cycle enzyme activity and pH value are feasible predictors of EMF; these factors were shown to be the main drivers of EMF of arable soils. Our findings suggest that there may be a limited degree of multifunctional redundancy in arable soils. The relationship we observed between microbial diversity and EMF suggests that management practices that foster more diverse soil microbial communities may have the potential to improve the functioning of agroecosystems. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Abstract: Subterranean detritivores such as earthworms can increase soil nutrient availability through their burrowing and casting activities. A number of recent studies have explored whether these changes caused by earthworms may in turn affect plant performance and resistance to herbivores, but no formal synthesis of this literature has been conducted to date. We tested for the effects of earthworms on plant growth, resistance and chemical defences against insect herbivores by performing a meta‐analysis of the existing literature up to 2016. We also explored ecological factors that might explain among‐studies variation in the magnitude of the earthworm effects on plant growth and resistance. We found that earthworm presence increases plant growth (by 20%) and nitrogen content (by 11%). Overall, earthworms did not affect plant resistance against chewing herbivores (caterpillars, slugs and rootworms), and even led to a 22% decrease in plant resistance against phloem‐feeding herbivores (aphids). However, earthworm presence increased production of chemical defences by 31% when plants where attacked by cell‐feeders (thrips), and resulted in an 81% increase in resistance against thrips. The magnitude of earthworm effects was stronger when earthworm inoculations consisted of a mix of species and ecological types, and when densities of earthworms were high. These results suggest that earthworm presence is an important factor underlying natural variation in plant defences against herbivores, and call for a better integration of the soil fauna in the studies of plant‐herbivore interaction, both for applied and fundamental research. A plain language summary is available for this article. [ABSTRACT FROM AUTHOR]

Tomoceridae is common but among the most problematic groups of Collembola. Its position within Collembola and the relationships within the family remain obscure. This also extends to the generic division of the subfamily Tomocerinae that remains controversial. This study examines these issues by integrating both molecular and morphological evidence. Our molecular phylogeny based on rDNA sequences supports the monophyly of Tomoceridae and the sister relationship between Tomocerinae and Lepidophorellinae. Reconstructions and tree topology tests constraining monophyly did not resolve the relationships between Tomoceridae and other collembolan groups. We also examined the morphology of the first instar (primary) larvae, which has significant phylogenetic value among higher Collembola. Mapping primary chaetotaxy onto our molecular phylogeny provided further evidence for the unique position of Tomoceridae within Entomobryomorpha and Collembola. The monophyly and subfamilial classification within Tomoceridae were validated here, whereas its position among Collembola will need further studies in a broader consideration across the major collembolan orders. Within Tomocerinae, the monophyly of Pogonognathellus was demonstrated, but the status of Tomocerus and Tomocerina is still to be resolved. [ABSTRACT FROM AUTHOR]

The aims of the present study were to compare the toxic effects of benzo[ a]pyrene (B aP) and to screen for rapid and sensitive biomarkers that can be used to assess the environmental risks of B aP in earthworms in different natural soil types. The authors exposed Eisenia fetida to 2 types of soil (red soil and fluvo-aquic soil) spiked with different concentrations (0 mg kg−1, 1 mg kg−1, 10 mg kg−1, 100 mg kg−1, and 500 mg kg−1) of B aP for 7 d or 14 d. Benzo[ a]pyrene-induced weight variation altered the activities of antioxidant enzymes (superoxide dismutase [SOD]; catalase [CAT]; and guaiacol peroxidase [POD]) and changed the content of malondialdehyde (MDA). In addition, using the comet assay, the authors determined the DNA damage in earthworms. The results revealed that the comet assay was suitable for evaluating the genotoxicity of B aP in the soil, even at the lowest examined concentration. The MDA content was the least sensitive indicator of B aP toxicity. A 3-way analysis of variance (ANOVA) was used to determine whether the soil type, exposure concentration, and duration affected the B aP toxicity. The antioxidant enzyme activities and the MDA content were shown to be significantly correlated with the exposure concentration. The percentage of weight variation ( p < 0.001), CAT activity ( p < 0.05), and SOD activity ( p < 0.01) were significantly affected by the soil type, and the POD activity ( p < 0.01), CAT activity ( p < 0.001), and SOD activity ( p < 0.001) were significantly affected by the exposure duration. Therefore, measuring DNA damage in earthworms is a simple and efficient means of assessing B aP genotoxicity in a terrestrial environment, and the effects of the soil type and exposure time on the other parameters that were investigated in E. fetida, which were used as responsive biomarkers, should be considered. Environ Toxicol Chem 2014;9999:1-8. © 2014 SETAC [ABSTRACT FROM AUTHOR]

The differences in soil inorganic-nitrogen (N) concentration and distribution, plant biomass, and root growth in the presence or absence of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) under different urea-application methods (placement versus homogeneously applied) were explored in a short-term microcosm experiment. Spring wheat ( Triticum aestivum L.) was grown in a microcosm with six different treatments: no amendment (CK), DMPP homogeneously applied (DMPP-hom), urea homogeneously applied (Urea-hom), urea with DMPP homogeneously applied (Urea + DMPP-hom), urea placement (Urea-place), and urea with DMPP placement (Urea + DMPP-place). After 28 d, plant biomass, soil inorganic nitrogen content, distribution of soil inorganic nitrogen and plant roots in the soil were analyzed. The soil inorganic N and plant roots tended to be distributed asymmetrically in the placement treatment but were distributed symmetrically in the homogeneous treatment. DMPP addition significantly increased the soil NH $ _4^+ $-N content and decreased the NO $ _3^- $-N content, especially near the fertilized zones in the placement treatment. Compared to the urea-only treatments, DMPP application significantly increased the shoot biomass and root lengths of the wheat in the homogeneous treatment but decreased them in the placement treatment. Therefore, homogeneously applied urea and DMPP may produce a more uniform nutrient distribution, leading to greater nitrogen retention in the soil and thus accelerating wheat growth. [ABSTRACT FROM AUTHOR]