Assembly Process Research Articles

Bacterial microbiome and their assembly processing in two sympatric desert rodents (Dipus sagitta and Meriones meridianus) from different geographic sources

Abstract The microbiome of mammals has profound effects on host fitness, but the process, which drives the assembly and shift of mammalian microbiome remains poorly understood. To explore the patterns of small mammal microbial communities across host species and geographical sites and measure the relative contributions of different processes in driving assembly patterns, 2 sympatric desert rodent species (Dipus sagitta and Meriones meridianus) were sampled from 2 geographically distant regions, which differed in the environment, followed by 16S rRNA gene sequencing. The microbiomes differed significantly between D. sagitta and M. meridianus, and linear mixed modeling (LMM) analysis revealed that microbial diversity was mostly affected by species rather than the environment. For each rodent species, the microbiome diversity and structure differed across geographical regions, with individuals from lower rainfall environments exhibiting greater diversity. The null modeling results suggested dispersal limitation and ecological drift rather than differential selective pressures acting on the microbiome. In addition, each group had a different core genus, suggesting that the taxonomic composition of the microbiome was shaped most strongly by stochastic processes. Our results suggest that variation in the microbiome between hosts, both within and among geographic rodent populations, is driven by bacterial dispersal and ecological drift rather than by differential selective pressures. These results elucidated the diversity patterns and assembly processes of bacterial microbiomes in small desert mammals. Deciphering the processes shaping the assembly of the microbial community is a premise for better understanding how the environment-host-microbe interactions of mammals are established and maintained, particularly in the context of increased environmental disturbances and global changes.

Hierarchical Assembly of High-Nuclearity Copper(I) Alkynide Nanoclusters: Highly Effective CO2 Electroreduction Catalyst toward Hydrocarbons.

The pursuit of precision in the engineering of metal nanoparticle assemblies has long fascinated scientists, but achieving atomic-level accuracy continues to pose a significant challenge. This research sheds light on the hierarchical assembly processes of two high-nuclearity Cu(I) nanoclusters (NCs). By employing a multiligand cooperative stabilization strategy, we have isolated a series of thiacalix[4]arene (TC4A)/alkynyl coprotected Cu(I) NCs (Cux, where x = 9, 13, 17, 22). These NCs are intricately coassembled from the fundamental building units of {Cu4(TC4A)} and alkynyl-stabilized Cu5L6 in various ratios. By capturing active anion templates such as O2-, Cl-, or C22- that are generated in situ, we have further explored the secondary structural self-assembly of these clusters. Cu13 serves as a secondary assembly module for constructing Cu38 and Cu43, which exhibit the highest nuclearity reported to date among Cu(I) NCs encased in macrocyclic ligands. Notably, Cu38 demonstrates an impressive Faradaic efficiency of 62.01% for hydrocarbons at -1.57 V vs RHE during CO2 electroreduction, with 34.03% for C2H4 and 27.98% for CH4. This performance establishes it as an exceptionally rare, large, atomically precise metal NC (nuclearity >30) capable of catalyzing the formation of highly electro-reduced hydrocarbon products. Our research has introduced a new approach for constructing high-nuclearity Cu(I) NCs through a hierarchical assembly method and investigating their potential in the electrocatalytic transformation of CO2 into hydrocarbons.

Habitat specificity modulates the bacterial biogeographic patterns in the Southern Ocean.

Conceptual biogeographic frameworks have proposed that the relative contribution of environmental and geographical factors on microbial distribution depends on several characteristics of the habitat (e.g. environmental heterogeneity, species diversity, proportion of specialist/generalist taxa), all of them defining the degree of habitat specificity, but few experimental demonstrations exist. Here, we aimed to determine the effect of habitat specificity on bacterial biogeographic patterns and assembly processes in benthic coastal ecosystems of the Southern Ocean (Patagonia, Falkland/Malvinas, Kerguelen, South Georgia and King George Islands), using 16S rRNA gene metabarcoding. The gradient of habitat specificity resulted from a 'natural experimental design' provided by the Abatus sea urchin model, from the sediment (least specific habitat) to the intestinal tissue (most specific habitat). The phylogenetic composition of the bacterial communities showed a clear differentiation by site, driven by a similar contribution of geographic and environmental distances. However, the strength of this biogeographic pattern decreased with increasing habitat specificity: sediment communities showed stronger geographic and environmental divergence compared to gut tissue. The proportion of stochastic and deterministic processes contributing to bacterial assembly varied according to the geographic scale and the habitat specificity level. For instance, an increased contribution of dispersal limitation was observed in gut tissue habitat. Our results underscore the importance of considering different habitats with contrasting levels of specificity to better understand bacterial biogeography and assembly processes over oceanographic scales.

Pinewood nematode induced changes in the assembly process of gallery microbiomes benefit its vector beetle's development.

Microbiomes play crucial roles in insect adaptation, especially under stress such as pathogen invasion. Yet, how beneficial microbiomes assemble remains unclear. The wood-boring beetle Monochamus alternatus, a major pest and vector of the pine wilt disease (PWD) nematode, offers a unique model. We conducted controlled experiments using amplicon sequencing (16S rRNA and ITS) within galleries where beetles and microbes interact. PWD significantly altered bacterial and fungal communities, suggesting distinct assembly processes. Deterministic factors like priority effects, host selection, and microbial interactions shaped microbiome composition, distinguishing healthy from PWN-infected galleries. Actinobacteria, Firmicutes, and Ophiostomataceae emerged as potentially beneficial, aiding beetle's development and pathogen resistance. This study unveils how nematode-induced changes in gallery microbiomes influence beetle's development, shedding light on microbiome assembly amid insect-pathogen interactions. Insights gleaned enhance understanding of PWD spread and suggest novel management strategies via microbiome manipulation.IMPORTANCEThis study explores the assembly process of gallery microbiomes associated with a wood-boring beetles, Monochamus alternatus, a vector of the pine wilt disease (PWD). By conducting controlled comparison experiments and employing amplicon approaches, the study reveals significant changes in taxonomic composition and functional adaptation of bacterial and fungal communities induced by PWD. It identifies deterministic processes, including priority effects, host selection, and microbial interactions, as major drivers in microbiome assembly. Additionally, the study highlights the presence of potentially beneficial microbes such as Actinobacteria, Firmicutes, and Ophiostomataceae, which could enhance beetle development and resistance to pathogens. These findings shed light on the intricate interplay among insects, microbiomes, and pathogens, contributing to a deeper understanding of PWD prevalence and suggesting innovative management strategies through microbiome manipulation.

Illumination-Induced Solute Uptake in Liquid Crystal Droplets: The Role of 5CB Excimers.

This study investigates the phenomenon of solute uptake into liquid crystal (LC) droplets, illuminated under UV light, focusing on the role of 4-cyano-4'-pentylbiphenyl (5CB) excimer formation in this process. Our experiments reveal that upon UV irradiation solute molecules, including surfactants and dyes, are actively drawn into the LC phase, forming distinctive assemblies within the droplets. Contrary to previous assumptions that the uptake was driven by the direct photoreactivity of the solutes, we found that the 5CB excimer state plays a critical role for this phenomenon. This state, identifiable through its photoluminescence yet invisible to conventional UV/vis absorption spectroscopy, correlates strongly with the molecular assembly process inside of the droplets. Notably, this mechanism operates across a broad spectrum of solute molecules, from simple surfactants like sodium dodecyl sulfate (SDS) to complex dyes, demonstrating the generality of the excimer-induced solute uptake. The excimer's role is pivotal, facilitating solute incorporation without reliance on their inherent light-absorbing properties. This insight not only advances our understanding of LC behavior under light irradiation but also opens new avenues for designing light-responsive materials.

The Study of the Balancing Process for Starting Rotors in Heavy-Duty Vehicles: An Industrial Application

In the heavy-duty vehicle industry, unbalance in the armature is one of the most common problems affecting starters’ performance and durability. This research presents a comprehensive study to improve the balancing process for starting rotors in heavy-duty vehicles. The complete manufacturing process of armatures was analyzed to understand the contribution of assembly processes to unbalancing. The analysis revealed that the primary factor leading to high unbalance in these parts is the misalignment of conductors within the armature winding. During assembly, these conductors experience axial movements, resulting in non-uniform mass distribution and causing unbalanced values ranging from 150 to 350 g·mm. These values surpass the permissible limit, making rectification during the balancing process at the end of the assembly impossible. Consequently, a novel alignment tool was designed to address this issue, significantly reducing the effect and achieving the maximum allowable unbalance of 100 g·mm. This allowed the balancing machine used in the process to correct the initial unbalance of the reinforcements in a single work cycle, improving operation efficiency by about 15%.

Gradient of acid mine drainage regulates microbial community assembly and the diversity of species associated with native plants

Acid mine drainage (AMD) is considered as one of the most important global environmental challenges. Therefore, understanding the impact of AMD on the diversity of microbial communities associated with native plants is important for phytoremediation. In this study, the community assembly and microbial diversity associated with native plants growing along an AMD impact gradient was investigated using metabarcoding and high throughput iChip technique. The study revealed that across both domains of bacteria and fungi, richness and species diversity decreased according to AMD impact. Bacterial species diversity was more stratified according to the pH gradient than fungi, and the AMD impact on the plant-associated microbial diversity decreased towards the plant roots. The microbial community composition of the undisturbed site was significantly different from the AMD impacted sites, and the communities in the AMD impacted sites were further stratified according to the degree of impact. The overall microbial diversity was mediated by the AMD impact, niche differences and plant species differences. Dispersal limitation was the most important community assembly process in the undisturbed site, while the homogenous selection of Burkholderia, Actinospica, Puia and Bradyrhizobium increased along the AMD impact gradient. Differential abundance analysis further revealed that Umbelopsis, Burkholderia and Sphingomonas were among the biomarkers of the AMD impacted sites. Several strains of some of these responsive genera were subsequently isolated using the iChip. Overall, this study presents novel insight into the ecology of plant-associated microbial communities that are relevant for environmental monitoring and for enhancing the revegetation of AMD impacted sites.

Deciphering stratified structure and microbiota assembly of biofilms from a pyrite-based biofilter driven by mixotrophic denitrification

The precise structure and assembly process of pyrite-based biofilms remain poorly understood. The polysaccharides (PN), proteins (PS), and extracellular DNA were enriched in the soluble extracellular polymeric substance (EPS), loosely bound EPS, and tightly bound EPS, respectively, indicating a significant stratified structure of biofilms. The tryptophan facilitated mixotrophic metabolic processes. Both dominant (>1%) and rare species (<0.01 %) harbored core bacteria, including sulfur autotrophic bacteria, sulfate-reducing bacteria, and heterotrophic bacteria. Furthermore, partial least-squares path modeling quantified the contributions of total phosphorus (TP) (λ = 0.32), dissolved organic matter (DOC) (λ = 0.29), and NH4+–N (λ = 0.26) to variations in the microbial community. Nonmetric multidimensional scaling analysis revealed three distinct stages in biofilm development: colonization (0–36 d), succession (36–149 d), and maturation/old (149–215 d). Furthermore, neutral community model indicated that stochastic processes drove the colonization and maturation/old stages, while deterministic processes dominated the succession stage. This study offered valuable insights into the regulation of pyrite-based engineered ecosystems.

Temperature governs the community assembly of root-associated ectomycorrhizal fungi in alpine forests on the Qinghai-Tibetan Plateau

Unraveling the assembly processes of ectomycorrhizal (ECM) fungal communities in changing environments is crucial for forecasting the impacts of climate change on forests. However, the assembly processes and key drivers of root-associated ECM fungal communities in alpine coniferous forests remain poorly understood. To address this knowledge gap, we conducted sampling in 65 monodominant alpine coniferous forests, which encompass 11 plant species belonging to three genera (Abies, Pinus, and Picea) within the Pinaceae family, all located on the Qinghai-Tibetan Plateau. We employed a combination of null model and multivariate analyses to elucidate the drivers and assembly processes of ECM fungal communities. Our results revealed significant variation in the composition and diversity of root-associated ECM fungal communities among Abies, Pinus, and Picea, indicating specific preferences for ECM fungi among Pinaceae genera. Importantly, mean annual temperature (MAT) emerged as the primary driver of these variations and regulated the assembly processes within the community of root-associated ECM fungi. As MAT temperature, the α-diversity of these fungi significantly decreased, suggesting that increased temperature may reduce the species diversity of root-associated ECM fungi in alpine forests. Furthermore, stochastic processes, such as dispersal limitation and drift, became more influential as MAT increased. Conversely, the role of deterministic processes, particularly heterogeneous selection, in shaping the ECM fungal community assembly weakened with increasing MAT. This study provides novel theoretical insights into the processes of ECM fungal community assembly in alpine forests, emphasizing the pivotal role of temperature in regulating the assembly processes and compositional dynamics of root-associated ECM fungal communities in these unique environments.

Model-based assembly process planning for flexible aircraft cabin architectures

The configuration and equipment of an aircraft cabin has a significant impact on the passenger’s flight experience. To meet the needs of passengers and improve the flight experience, airlines repeatedly demand customised adaptations to the cabin design. The implementation of these changes requires a high degree of flexibility in production and can lead to difficulties in setting up a fixed final assembly line. In addition, unforeseen events and changes in the OEMs’ supply chain require a rapid response in aircraft production to be able to deliver on time. Digitalisation in product development and production planning makes it possible to overcome these challenges and makes an important contribution to flexibility, time and cost efficiency. This paper presents a digital approach to modelling and flexible planning of assembly processes of the cabin. To this end, aircraft design data is automatically linked to the assembly system to react quickly to design changes in the assembly planning process. The integration is realised in a system architecture model depicted with the systems modelling language (SysML). The architecture model follows the formal process description defined in VDI3682. A planning algorithm then uses the production architecture parameters to optimise the assembly processes, e.g. in terms of time. The approach presented is demonstrated using the example of scheduling the pre-assembly processes of the "crown module". The latter includes all structural and functional components above the window panels, such as overhead bins, electrics and air conditioning. The results show how changes in aircraft and cabin design or in the production plant and resources can be flexibly evaluated. This allows conceptual changes to be evaluated and traded before the cabin design is frozen and transferred to real production. These advantages contribute to the time and cost optimisation of aircraft production. This work thus makes a valuable contribution to the further development of digital solutions in aircraft production.

Stability analysis of deep foundation pit with a double-row cast-in-place piles and diagonal steel lattice braces under sloped excavation conditions

Existing deep foundation pit support structures are commonly composed of external earth-retaining structures, internal horizontal bracings, and vertical columns. A closed bracing system, often formed by a horizontal support through a bracket board, frequently impedes vertical excavation and soil removal operations in the foundation pit, and the processes of assembly and dismantling are complex and time-consuming. This study presents a combined support system and construction method consisting of cast-in-place piles and diagonal steel lattice braces. For sloped excavation, diagonal braces were constructed by slotting through the reserved soil, allowing the use of a single layer of support within the excavation depth. This approach significantly optimizes the construction process, reducing both project duration and overall cost. The field monitoring results indicated that the support method effectively controlled the lateral displacement of the pile bodies. Field monitoring results demonstrated that the proposed support system effectively controlled the lateral displacement of the pile bodies. The adoption of a support-first, excavation-second approach significantly controlled the settlement of the ground surface around the foundation pit, thereby preventing excessive increments in the axial force of the supports due to the large longitudinal depth excavation. The calculation results of the three-dimensional finite element model for foundation pit excavation and support indicate that the proposed support method results in a decreasing ratio of the maximum lateral deformation depth of the pile body, denoted as δh-m, to the excavation depth He as the excavation depth increases. This implied that the displacement of the pile body was strictly controlled. When the depth of the foundation pit excavation exceeded 10 m, the maximum lateral deformation occurred below 10 m along the pile shaft. The diagonal steel lattice braces transferred the load to the top of the cast-in-place piles at the bottom of the pit, where the stress concentration occurred. During construction, special attention must be paid to the strength of the connection between the pile top and the connecting beams.

Preparation and characterisation of IPMC brakes modified with composite electrodes performance

Ionic Polymer Metal Composite (IPMC) can be used as flexible actuators and sensors in the fields of bionic machinery and medical devices. However, IPMC still suffer from poor actuation performance and high cost of electrode preparation in practical applications. Optimisation of electrodes and use of novel assembly processes are expected to solve these problems. In this paper, low-dimensional nanocarbon materials were used to modify the Nafion membrane. Appropriate amounts of carbon nanotubes and carbon black were weighed and dispersed in chitosan and acetic acid to form a stable electrolyte. A new IPMC was prepared by bonding carbon nanotube and carbon black films on the Nafion membrane using the hot pressing method. Scanning electron microscope images showed that the hybrid films composed of carbon nanotubes and carbon black were successfully hot pressed onto the surface of the Nafion membrane and the hybrid electrode layer composed of carbon nanotubes and carbon black was more homogeneous and densely packed. The results of driving performance tests show that the hybrid electrode-modified IPMC has excellent driving performance, with a maximum output displacement of 9.2 mm and a maximum output force of 9.9 mN at a voltage of 5.0 V. These results are 1.07 and 1.14 times higher than those of the carbon nanotube IPMC and 1.74 and 1.70 times higher than those of the carbon black IPMC under the same conditions, respectively.

Seismic performance of prefabricated repairable RCS joints with replaceable multi-segment weakened plates

In order to enable the high-efficiency and easy-operation repairment of prefabricated reinforced concrete column-steel beam (RCS) structure after damage, a novel replaceable assembly RCS joint with multi-segment weakened plate (RCS-MWP) is proposed in this research. The design theory, construction, assembly process, replacement of MWP components and repairment after damaged were introduced. This configuration encompasses three sub-specimens: RCS-MWP, RCS-MWP1, and RCS-MWP2, with varying parameters such as pad thickness and number of weakened segments. For RCS-MWP1 and RCS-MWP2, only the energy dissipation components were replaced after the RCS-MWP were tested and damaged. A comparative study was conducted with a traditional RCS joint with a bolt connection (RCS-B). The test results indicated that the damage to the four specimens (RCS-B, RCS-MWP, RCS-MWP1, and RCS-MWP2) was mainly concentrated at the energy dissipation components, while the reinforced concrete (RC) columns and steel beams remained in the elastic stage with minimal damage. By comparing the RCS-MWP, RCS-MWP1, and RCS-MWP2 specimens, it was observed that RCS-MWP and RCS-MWP2 exhibited second-order buckling, which improved the bearing capacity and energy dissipation capacity. The cumulative energy dissipation of specimens with 8 mm pads in the multi-segmental weakened plate assemblies (RCS-MWP1 and RCS-MWP2) increased by 9% and 59.4% compared to RCS-MWP with 3 mm pads, providing enhanced nodal energy dissipation. The average positive and negative bearing capacities of RCS-B were 70.6% higher than those of the RCS-MWP group, which was caused by the low yield stress of multi-segment weakened plates. After eliminating the residual displacement of specimen RCS-MWP, the seismic performance of the RCS-MWP1 and RCS-MWP2 specimens was barely decreased after diagonally replacing the energy dissipation components. This demonstrates the rationality and feasibility of using replaceable MWP components to repair RCS-MWP joints after the earthquake. It should be noted that the residual displacements after unloading resulted in the restoration of the joints more challenging, hence, prestressing to achieve self-centering could be considered as a potential topic for future research. This proves the feasibility of replacing energy-consuming components.

Bacterial community and antibiotic resistance genes assembly processes were shaped by different mechanisms in the deep-sea basins of the Western Pacific Ocean.

As the intrinsic property of microorganisms, antibiotic resistance genes (ARGs) are fundamentally coupled to microbially-linked biogeochemical processes within ecosystems. However, human activities often obscure the natural distribution of ARGs through deterministic selective pressures. The deep-sea basin of the western Pacific Ocean is one of the least disturbed areas globally by human activities, providing a natural laboratory to investigate the intrinsic mechanisms governing ARGs in natural environments. In this study, we analyzed bacterial community and ARG diversity in 15 surface sediment samples from three deep-sea basins in the western Pacific Ocean. The relative abundance of ARGs in the surface sediments ranged from 3.10 × 10-3 to 5.37 × 10-2 copies/16S rRNA copies, with multidrug and β-lactam resistance genes dominated in all samples (49.06%-100%). The bacteria were mainly dominated by the Proteobacteria. The principal coordinate analysis (PCoA) showed significant spatial heterogeneity of ARGs and bacteria among the three basins. Null model, neutral community models (NCM), and normalized stochasticity ratio (NST) indicated that bacterial community was dominated by stochastic assembly, driven by geographic barriers leading to independent evolution. Conversely, the NST revealed that the ARGs profile was mainly shaped by deterministic processes. Environmental factors are more crucial than geographical factors and bacterial community for ARG occurrence among the selected factors. Meanwhile, we found that the spread of ARGs was mainly through vertical gene transfer in the pre-antibiotic era. The disparity between the assembly processes of bacterial community and ARGs may be attributed to the fact that ARG hosts were not the dominant bacteria in the community. This study first reported the distribution and assembly processes of ARGs and bacterial community in surface sediments of the western Pacific.

RANCANG BANGUN PROTOTYPE SMART GREENHOUSE MENGGUNAKAN THINGSPEAK

The design of this smart greenhouse prototype is one of the implementations of artificial intelligence controlled by the Arduino uno microcontroller, which has actuators in the form of lights and pumps and is equipped with DHT22 sensors, Soil Moisture and Temperature Sensors. The method used in making this smart greenhouse prototype is the Prototype method. There are seven stages in the prototype method that guide the process of making robots, namely gathering requirements, building prototypes/prototypes, evaluating prototypes, programming systems, testing systems, evaluating systems, and using the system. The most important stage in making this smart greenhouse prototype is the stage where at this stage testing is carried out on the results of the design and programming of the robot that has been made to prove the robot prototype is in accordance with what is desired or not. The testing process is carried out in tandem with the assembly process and programming process. In the process of assembling and programming the robot prototype, it is done with system errors. Testing with system errors is carried out to get a robot prototype that works optimally.

Temperature sensitivity quandary of soil microbial community structure in Tibetan alpine grasslands: A meta-analysis and field experiment

Soil microorganisms act as the primary decomposers in global terrestrial ecosystems. Whether climate warming will lead to the convergence of the temperature sensitivity of soil microbial community structure and the convergence of the responses of soil microbial community structure to warming remains controversial. This study explored how warming amplitude affected the temperature sensitivity of soil bacteria and fungi community structures, and how it influenced the responses of soil bacteria and fungi community structures to warming on the Qinghai-Tibet Plateau based on meta-analysis and a single-site warming experiment. The temperature sensitivity of soil microbial community structure did not consistently decline with increasing warming magnitude; instead, it even rose, which might be associated with the nonlinear relationships of the warming magnitude with the temperature sensitivity of ecological processes of soil microbial community assembly or the topological parameters of species co-occurrence network. Meta-analysis indicated that responses of soil microbial community to warming were independent of warming amplitude. However, the single-site warming experiment demonstrated that responses of soil microbial community to warming varied with warming amplitude. These inconsistent results might be attributed to distinct spatial scales, grassland types, climatic conditions and warming magnitudes between the single-site experiment and the meta-analysis. Therefore, the temperature sensitivity of soil microbial community and its response to climate warming cannot be simply characterized as monotonically decreasing or increasing in relation to increasing warming magnitude.

Decoding Silent Speech Cues From Muscular Biopotential Signals for Efficient Human‐Robot Collaborations

AbstractSilent speech interfaces offer an alternative and efficient communication modality for individuals with voice disorders and when the vocalized speech communication is compromised by noisy environments. Despite the recent progress in developing silent speech interfaces, these systems face several challenges that prevent their wide acceptance, such as bulkiness, obtrusiveness, and immobility. Herein, the material optimization, structural design, deep learning algorithm, and system integration of mechanically and visually unobtrusive silent speech interfaces are presented that can realize both speaker identification and speech content identification. Conformal, transparent, and self‐adhesive electromyography electrode arrays are designed for capturing speech‐relevant muscle activities. Temporal convolutional networks are employed for recognizing speakers and converting sensing signals into spoken content. The resulting silent speech interfaces achieve a 97.5% speaker classification accuracy and 91.5% keyword classification accuracy using four electrodes. The speech interface is further integrated with an optical hand‐tracking system and a robotic manipulator for human‐robot collaboration in both assembly and disassembly processes. The integrated system achieves the control of the robot manipulator by silent speech and facilitates the hand‐over process by hand motion trajectory detection. The developed framework enables natural robot control in noisy environments and lays the ground for collaborative human‐robot tasks involving multiple human operators.

Regional and local patterns of soil arthropod diversity are explained by different processes in southwest China

Understanding the distribution patterns and underlying mechanisms of community assembly at different spatial scales is crucial for the ecology and conservation of organisms, yet little is known about soil arthropods. In this study, we tested the relative importance of the two hypotheses that could explain soil arthropod distribution patterns at local and regional scales: (1) the habitat heterogeneity hypothesis (spatial complexity and variability of a habitat allow the coexistence of many species), and (2) the more-individuals hypothesis (the amount of resources per se, regardless of its spatial heterogeneity, increases overall soil arthropod abundance and richness). We extensively collected soil arthropods (identified to families or subfamilies) and measured soil physicochemical properties in four forests distributed across latitudes in Yunnan Province, China. We found that soil arthropod abundance and taxon richness increased with increasing latitudes, contrasting with the generally known pattern for plants and aboveground animals. Litter biomass (resources) explained the taxon richness and abundance at the regional scale, which aligned with the more-individuals hypothesis. Other soil physicochemical properties (e.g., Ca, TP, Mg, Mn, and pH) were more important at the local scale, underpinning the habitat heterogeneity hypothesis. However, the relative importance of individual soil properties was highly location-specific, suggesting that the environmental factors operating in one location do not necessarily reflect those operating in others at different latitudes. These findings improve our understanding of the community assembly and ecological processes of soil arthropods at different spatial scales, which is vital for predicting the future of soil biodiversity.

The role of foraging pollinators in assembling the flower microbiota and transmitting the fire blight pathogen Erwinia amylovora.

Flowers serve as hubs for biotic interactions with pollinators and microbes, which can significantly impact plant reproduction and health. Previous studies have shown that the flower microbiota undergoes dynamic assembly processes during anthesis. However, the influence of foraging pollinators on the assembly and dispersal of the flower microbiota and the transmission of plant pathogens remains poorly understood. In this study, we used insect exclusion netting to investigate the role of pollinators in the assembly of the microbiota on apple stigma and the transmission of the fire blight pathogen Erwinia amylovora. We found that excluding pollinators had a minor impact on the community diversity and composition of the apple stigma microbiota, while the flower's developmental stage had a strong influence. Additionally, pollinator exclusion altered bacterial dispersal and the relative abundance of different bacterial species, including E. amylovora, suggesting that pollinators play a role in transmitting plant pathogens. Using a reporter system, we demonstrated that bumble bees can transmit the fire blight pathogen from an infected flower under controlled growth conditions. Our study highlights the importance of intrinsic and pollinator-independent microbes as sources of inoculum for the stigma microbiota and underscores the role of foraging pollinators in vectoring plant pathogens.

Positive plant diversity effects on soil detritivore feeding activity and stability increase with ecosystem age

Increasing species diversity frequently enhances ecosystem functioning - a pattern strengthened with ecosystem age. It has been suggested that strengthened responses over time may be due to community assembly processes and cumulative effects over the history of interactions between and among plant and soil communities. However, most soil studies are conducted with destructive one-time samplings, and little is known about how phenological patterns of soil activity change with biodiversity and ecosystem age. Here, we investigate phenology metrics related to soil detritivore feeding activity (i.e., duration, total magnitude, variability), measured via the bait-lamina method, in a long-term grassland biodiversity experiment that included an experimental removal of plant and soil history, resulting in older and younger assembled plant and soil communities. Detritivore feeding activity peaked in spring and/or early summer, with another short increase in fall. Increased plant species richness enhanced the total magnitude and variability (i.e., the coefficient of variation) of detritivore feeding activity. Plant and soil history enhanced the buffering effects of plant richness on variability, causing older plant and soil communities to have the strongest relationships between plant richness and stability. However, older plant and soil communities showed the shortest duration of detritivore feeding activity, and species richness was not important in changing activity duration. These findings underscore the importance of considering ecosystem age as a critical component that modifies plant diversity effects on ecosystem functioning, with important implications for promoting ecosystem stability and resilience under environmental change.