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Deforestation and slash combustion have substantial adverse impacts on the atmosphere, soil and microbe. Despite this awareness, numerous individuals persist in opting for high-intensity Eucalyptus planting through slash-burning in pursuit of immediate profits while disregarding the environmental significance and destroying the soil. Slash-unburnt agriculture can effectively safeguard the ecological environment, and compared with slash-burning, there remains a limited understanding of its regulatory mechanisms on soil fertility and microbial community. Also, large uncertainty persists regarding the utilization of harvest residues. Thoroughly investigating these questions from various perspectives encompassing physical soil characteristics, nutrient availability, bacterial community structures, and stability is crucial. To explore the ecological advantages of slash-unburnt techniques on microorganisms and their associated ecosystems, we used two slash-unburnt (Unburnt) planting techniques: Spread (naturally and evenly covering the forest floor after logging) and Stack (residues are piled along contour lines) as well as the traditional slash Burnt method (Burnt) in a Eucalyptus plantation. A comparative analysis was conducted between the two methods. We observed that over a span of 4 years, despite the initial lower application of fertilizer in the Unburnt treatments compared with the Burnt treatment during the first 2 years, the Unburnt treatment gradually caught up or even surpassed and attained similar nutrient levels as the Burnt treatment. Alphaproteobacteria was the main phyla that indicated the difference in soil bacterial communities between Burnt and Unburnt treatments. The microbial networks also highlighted the significance of the Unburnt method, as it contributed to the preservation of crucial network nodes and the stability of soil bacterial communities. Therefore, rational utilization of harvest residue may effectively avoid the vast damage caused by slash-burning to Eucalyptus trees and the soil environment but may also increase the potential for restoring soil fertility, improving fertilizer utilization efficiency, and maintaining microbial community stability over time., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Lichao Wu reports financial support was provided by China National Key Research and Development Program during the 14th Five-year Plan Period (Grant No. 2023YFD2201003). Huili Wang reports financial support was provided by Natural Science Foundation of Guangxi Province (Grant No. 2022GXNSFBA035578). Lijun Chen reports financial support was provided by National Natural Science Foundation of China (Grant No. 32301568). If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Plant-microbe interactions can modulate the plant metabolome, but there is no information about how different soil microbiomes could affect the sugarcane metabolome and its quality. Here, we collected soil and stalk samples from bitter sugarcane (BS) and sweet sugarcane (SS) to conduct chemical analysis, microbiome and metabolome analysis. Our data revealed lower species diversity in the BS group than in the SS group, and 18 discriminatory OTUs (relative abundance ≥ 0.01%) were identified. Sugarcane metabolomic analysis indicated the different abundances of 247 metabolites between the two groups in which 22 distinct metabolites involved in two flavonoid biosynthesis pathways were revealed. Integrated analysis between soil microbial taxa, stalk chemical components, and soil properties showed that the flavonoid content in stalks and the nitrogen concentration in soil were highly correlated with the soil microbiome composition. Bacteria at the genus level exhibited greater associations with distinct metabolites, and six genera were independently associated with 90.9% of the sugarcane metabolites that play a major metabolic role in sugarcane. In conclusion, this study provided evidences that the interaction between plant-microbiome can change the plant metabolome.

Soil microbial respiration is an important source of uncertainty in projecting future climate and carbon (C) cycle feedbacks. However, its feedbacks to climate warming and underlying microbial mechanisms are still poorly understood. Here we show that the temperature sensitivity of soil microbial respiration (Q 10 ) in a temperate grassland ecosystem persistently decreases by 12.0 ± 3.7% across 7 years of warming. Also, the shifts of microbial communities play critical roles in regulating thermal adaptation of soil respiration. Incorporating microbial functional gene abundance data into a microbially-enabled ecosystem model significantly improves the modeling performance of soil microbial respiration by 5-19%, and reduces model parametric uncertainty by 55-71%. In addition, modeling analyses show that the microbial thermal adaptation can lead to considerably less heterotrophic respiration (11.6 ± 7.5%), and hence less soil C loss. If such microbially mediated dampening effects occur generally across different spatial and temporal scales, the potential positive feedback of soil microbial respiration in response to climate warming may be less than previously predicted.

Background: Freeze-thaw influences soil-dissolved nitrogen (N) pools due to variations in bacterial communities in temperate regions. The availability of soil water is important to soil biogeochemical cycles under frozen conditions. However, it is unclear how soil water content (SWC) mediates the effects of freeze-thaw on soil-dissolved N pools and bacterial communities., Method: In this study, freeze-thaw microcosms were incubated at three levels of SWC, including 10% (air-dried soils), 15% (natural SWC), and 30% (wet soils). In addition to measuring soil-dissolved N pools, variations in bacterial communities were examined using high-throughput sequencing. Results and Conclusions . Total dissolved N (TDN), NO 3 - -N, NH 4 + -N, microbial biomass N (MBN), and net N mineralization rate (NNMR) were significantly influenced by SWC, freeze-thaw, and their interaction (NH 4 + -N excluded). N immobilization was inhibited under both low and high SWC, which was accompanied by varied bacterial community composition. However, only higher SWC substantially modified the freeze-thaw effects on the soil-dissolved N pools, characterized by a decrease in N mineralization (especially for the content of NO 3 - -N and NNMR) and an increase in N immobilization (MBN). These scenarios could be significantly correlated to variations in bacterial community composition based on redundancy analysis, especially by species belonging to Bacteroidetes , Nitrospirae , Alphaproteobacteria , Gemmatimonadetes , and Verrucomicrobia (Spearman's correlations). In conclusion, bacterial species passed through biotic (bacterial species) and abiotic filters (soil N pools) in response to freeze-thaw under varied SWC. Bacteroidetes , Nitrospirae , Alphaproteobacteria , Gemmatimonadetes , and Verrucomicrobia (Spearman's correlations). In conclusion, bacterial species passed through biotic (bacterial species) and abiotic filters (soil N pools) in response to freeze-thaw under varied SWC. Nitrospirae , Alphaproteobacteria , Gemmatimonadetes , and Verrucomicrobia (Spearman's correlations). In conclusion, bacterial species passed through biotic (bacterial species) and abiotic filters (soil N pools) in response to freeze-thaw under varied SWC. Alphaproteobacteria , Gemmatimonadetes , and Verrucomicrobia (Spearman's correlations). In conclusion, bacterial species passed through biotic (bacterial species) and abiotic filters (soil N pools) in response to freeze-thaw under varied SWC. Gemmatimonadetes , and Verrucomicrobia (Spearman's correlations). In conclusion, bacterial species passed through biotic (bacterial species) and abiotic filters (soil N pools) in response to freeze-thaw under varied SWC. Verrucomicrobia (Spearman's correlations). In conclusion, bacterial species passed through biotic (bacterial species) and abiotic filters (soil N pools) in response to freeze-thaw under varied SWC., Competing Interests: The authors have no conflicts of interest to declare., (Copyright © 2020 Nan Jiang et al.)

Soil microorganisms play a crucial role in the bioremediation of pentachlorophenol (PCP)-contaminated soils. However, whether and how soil bacterial networks with keystone taxa affect PCP dechlorination is not well understood. The present study investigated the effects of citrate on soil bacterial networks mediating PCP dechlorination by direct and indirect transformation in iron-rich upland and paddy soils. The rates of PCP dechlorination and Fe(II) generation were accelerated by citrate addition, particularly in the paddy soils. Network analysis revealed that the topological properties of bacterial networks were changed by citrate addition; more modules and keystone taxa were significantly correlated with PCP dechlorination and Fe(II) generation in the networks. Random forest modeling indicated that Clostridiales was the most important bacterial order; it was significantly involved in both the direct and indirect pathways of PCP dechlorination. Citrate addition had less influence on the balance between the direct and indirect pathways of PCP dechlorination in the upland soils, whereas it enhanced biological PCP dechlorination more directly and efficiently in the paddy soils. Our results suggested that land-use type and citrate addition play a critical role in controlling the biogeochemical mechanisms of PCP dechlorination., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this study, experiments were performed using network analysis to investigate the effects of different carbon sources, including blank, citrate, glucose and lactate, on indigenous bacterial communities and on the pentachlorophenol (PCP) dechlorination in two soils. Kinetics results demonstrate that PCP dechlorination is significantly enhanced by adding citrate/lactate, but to a lesser extent by adding glucose. High-throughput sequencing results revealed that Firmicutes and Proteobacteria were the dominant groups in these four different treatments during the PCP dechlorination, whereas random forest analysis indicated that the orders Clostridiales, Haloplasmatales, Bacillales, Pseudomonadales and Gaiellales were the critical bacterial orders in modules that were significantly correlated with PCP dechlorination. Among them, the relative abundance of Clostridiales dramatically increased in both citrate and lactate treatment, further accelerating the PCP dechlorination. Addition of citrate/lactate as the carbon source increased the bacterial co-occurrence network density, average clustering coefficient and modularity. Moreover, more modules significantly correlated with PCP dechlorination in the citrate/lactate networks compared with the glucose/blank networks. Random forest modeling suggested that Clostridiales played a critical role in these functional modules. Taken together, our results provide insight into the biological mechanism of the impact of exogenous carbon sources on PCP dechlorination pathways by modifying soil bacterial networks., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The bacterial phoD gene encodes alkaline phosphomonoesterase, an enzyme which plays an important role in the release of plant-available inorganic phosphorus (P) from organic P in soil. However, the relationships between phoD gene community, alkaline phosphomonoesterase activity, and P availability in soil are poorly understood. In this study, we investigated how alkaline phosphomonoesterase activity, phoD gene abundance, and community structure are influenced by plant-available P using soils (0-10, 10-20 and 20-40 cm) from a long-term field trial in which a continuous maize (Zea mays L.) crop had received different levels of P fertilizer inputs (30, 60 kg P ha -1  year -1 ) for 28 years. Quantitative PCR and high-throughput sequencing were used to analyze phoD gene abundance and community composition. Alkaline phosphomonoesterase enzyme activity was negatively correlated with soil available P, which was reflected in corresponding data for phoD gene abundance. On the other hand, positive correlations were determined between phoD gene α-diversity and available P, while shifts in phoD gene community structure were related to changes in soil pH and P availability. The relative abundance of Pseudomonas was negatively correlated with P availability and positively correlated with alkaline phosphomonoesterase activity, suggesting that Pseudomonas may play an important role in soil organic P mineralization. The findings of this study demonstrated that changes of soil P availability as a result of long-term P fertilizer inputs significantly affected alkaline phosphomonoesterase activity by regulating phoD gene abundance, diversity, as well as altering the phoD gene community composition., (Copyright © 2019. Published by Elsevier B.V.)

Background: Biochar amendments have been widely proposed as a conventional and efficient strategy to promote soil organic carbon (SOC) sequestration via negative priming. Unfortunately, the extent and biological mechanisms responsible for biochar-induced negative priming are still not fully understood. Despite traditional explanations focused on the environmental filtering mechanisms of biochar amendments on microbial biomass and community composition underlying the priming effect on SOC dynamics, whether and how a biochar-induced competitive interaction with keystone taxa determines SOC mineralization in natural ecosystems has been minimally explored., Results: Here, we paid particular attention to the relationships between the diversity and network structure of soil bacterial and fungal communities and SOC mineralization. A 3-year field experiment was conducted comprising five treatments: no fertilization, conventional fertilization, and conventional fertilization with three rates of biochar amendments. Biochar amendments considerably increased soil moisture capacity and pH and subsequently shaped the composition and co-occurrence networks of soil bacterial and fungal communities. Importantly, network analysis revealed that the biochar amendments triggered the competitive interaction with putative keystone taxa in the bacterial and fungal networks. Structural equation modeling suggested that the competitive interaction with keystone taxa promoted bacterial and fungal diversity and consequently reduced carbohydrate catabolism and soil metabolic quotient. Stable isotope probing incubations further provided consistent evidence of competition by keystone taxa with the increases in bacterial and fungal diversity under the biochar amendments., Conclusions: We found that biochar-induced competition with keystone taxa stimulated the bacterial and fungal diversity and consequently decreased SOC mineralization. The comprehensive understanding of the unexplored biological mechanisms underlying the biochar-induced negative priming may provide crucial implications for enabling SOC sequestration.

Freeze-thaw (FT) events can influence soil functions. However, the overall impact of FTs on soil bacterial communities, especially in temperate regions, remains unclear. In this study, soil samples were collected from a midtemperate region in the northeast of China, and three incubation tests were then designed with varied FT amplitudes (i.e., at a freezing temperature of -15, -9, and -3°C, respectively), frequencies of FT cycles (i.e., under one, six, and 15 FT cycles, respectively) and soil water content (SWC) values (i.e., at 10 and 30% SWC, respectively). High-throughput sequencing of 16S rRNA gene amplicons was performed and the functional profile was further predicted based on these data, in addition to examinations of bulk microbial properties. Data analyses suggested that, first of all, the FT amplitude significantly influenced the bulk microbial properties and bacterial community (composition and function); certain taxa showed a nonlinear response to the three amplitudes. Next, compared to a single FTC, multiple FT cycles had only minor effects on the bacterial functional capabilities, although the bulk microbial properties changed significantly after multiple FT cycles. In addition, the bacterial response to FTs was influenced by the SWC, characterized by the significantly different bacterial community structures (composition and function) and the opposite trends of enzyme activities. Finally, RDA plots and a correlation network assembled data from all soil samples across the three tests and suggested that bacterial response trajectories changed because some species were influenced mainly by other species (i.e., biotic environment) during FT processes.

Nematode predation has important roles in determining bacterial community composition and dynamics, but the extent of the effects remains largely rudimentary, particularly in natural environment settings. Here, we investigated the complex microbial-microfaunal interactions in the rhizosphere of maize grown in red soils, which were derived from four long-term fertilization regimes. Root-free rhizosphere soil samples were separated into three aggregate fractions whereby the abundance and community composition were examined for nematode and total bacterial communities. A functional group of alkaline phosphomonoesterase (ALP) producing bacteria was included to test the hypothesis that nematode grazing may significantly affect specific bacteria-mediated ecological functions, that is, organic phosphate cycling in soil. Results of correlation analysis, structural equation modeling and interaction networks combined with laboratory microcosm experiments consistently indicated that bacterivorous nematodes enhanced bacterial diversity, and the abundance of bacterivores was positively correlated with bacterial biomass, including ALP-producing bacterial abundance. Significantly, such effects were more pronounced in large macroaggregates than in microaggregates. There was a positive correlation between the most dominant bacterivores Protorhabditis and the ALP-producing keystone 'species' Mesorhizobium. Taken together, these findings implicate important roles of nematodes in stimulating bacterial dynamics in a spatially dependent manner.

Archaea substantially contribute to global geochemical cycling and energy cycling and are impacted by land-use change. However, the response of archaeal communities to a change from upland field to paddy field has been poorly characterized. Here, soil samples were collected at two depths (0-20 cm and 20-40 cm) from one upland field and six paddy fields that were established on former upland fields at different times (1, 5, 10, 20, 30, and 40 years before the study). Barcoded pyrosequencing was employed to assess the archaeal communities from the samples at taxonomic resolutions from phylum to genus levels. The total archaeal operational taxonomic unit (OTU) richness showed a significant positive correlation with the land-use change duration. Two phyla, Euryarchaeota and Crenarchaeota, were recorded throughout the study. Both the relative abundance and OTU richness of Euryarchaeota increased at both depths but increased more steadily at the subsurface rather than at the surface. However, these data of Crenarchaeota were the opposite. Additionally, the archaeal composition exhibited a significant relationship with C/N ratios, total phosphorus, soil pH, Olsen phosphorus, and the land-use change duration at several taxonomic resolutions. Our results emphasize that after a change from upland fields to paddy fields, the archaeal diversity and composition changed, and the duration is an important factor in addition to the soil chemical properties.

A field experiment was carried out at the Shenyang Experimental Station of Ecology (CAS) in order to study the effects of slow-release urea fertilizers high polymer-coated urea (SRU1), SRU1 mixed with dicyandiamide DCD (SRU2), and SRU1 mixed with calcium carbide CaC2 (SRU3) on urease activity, microbial biomass C and N, and nematode communities in an aquic brown soil during the maize growth period. The results demonstrated that the application of slow-release urea fertilizers inhibits soil urease activity and increases the soil NH4+-N content. Soil available N increment could promote its immobilization by microorganisms. Determination of soil microbial biomass N indicated that a combined application of coated urea and nitrification inhibitors increased the soil active N pool. The population of predators/omnivores indicated that treatment with SRU2 could provide enough soil NH4+-N to promote maize growth and increased the food resource for the soil fauna compared with the other treatments.

This paper studied the dynamics of microbial biomass N in a black soil long-term fertilized with farmyard manure (M2 and M4) and chemical fertilizer (NPK) during crop growth season. The results showed that the soil microbial biomass N was 25.52-239.12 mg x kg(-1) in M4, 10.40-94.31 mg x kg(-1) in M2, 6.27-87.04 mg x kg(-1) in NPK, and 9.15-69.81 mg x kg(-1) in CK. In same treatment, the highest value was 7-14 times higher than the lowest value. Treatments NPK and M2 had the highest value of microbial biomass N at reproductive growth stage, while M4 and CK had it at vegetative growth stage. The significant difference of soil microbial biomass N caused by different treatments was not changed with plant growth stages. The dynamics of soil microbial biomass N had a significant correlation some soil biological, physical and chemical properties. A significant positive correlation was found between soil microbial biomass N and soil biological, physical and chemical properties, plant N, P and K contents, soil moisture, and grain crude protein.

This paper studied the microbial biomass P in a long-term fertilized black soil. The soil was fertilized by farmyard manure (M2, M4) and chemical fertilizer (NPK), and the dynamics of soil microbial biomass P was monitored during crop growth season. The results showed that the microbial biomass P in different treatments was 8.75-47.68 mg x kg(-1) (M4), 3.02-37.16 mg x kg(-1) (M2), 1.59-10.62 mg x kg(-1) (NPK), and 0.76-6.74 mg x kg(-1) (CK). The microbial biomass P in M4 and M2 was the highest at reproductive growth stage, and that in NPK and CK was the highest at early growth stage. The significant difference of soil microbial biomass P induced by different amounts and types of fertilizer application was not varied with the period and stage of plant growth. In all treatments, no significant correlation was found between the dynamics of soil microbial biomass P and the soil biological, physical and chemical properties in plant growth period. Soil microbial biomass P had a very significant positive correlation with soil biological, physical and chemical properties (expect K), and a significant positive correlation with the N, P and K contents of plants and soil water content.

With an aquic brown earth as test soil, this paper studied the effects of urease inhibitor (NBPT), nitrification inhibitor (DCD) and their combinations on the dynamics of soil available N and microbial biomass N. The results showed that the treatments of inhibitors, especially the combined application of NBPT and DCD, could increase soil NH4+-N by 2%-53%, inhibit NH4+ oxidation, decrease soil NO3(-)-N concentration, increase soil total available N by 34%-44%, and increase wheat N uptake by 0.26%-6.79%. The best treatment was urease inhibitor combined with nitrification inhibitor. The application of inhibitors increased soil microbial biomass N immobilization at the early growth stage of wheat, and promoted soil N mineralization at filling stage.

The effect of long-term fertilization on the dynamics of microbial biomass C in a typical black soil of Northeastern China was studied in a field trail treated by different fertilizations. The results showed that the amount of soil microbial biomass C under different fertilizations varied significantly with growth stages. It was the highest in farmyard manure (M2 and M4) treatments, with a less seasonal fluctuation, second in NPK treatment, the peak at sowing period, and the lowest in CK, the peak at wax maturity stage. No significant correlation was found between the dynamic changes of soil microbial biomass C and soil biological, physical and chemical properties in all treatments, but the correlation of soil microbial biomass C with the contents of N, P and K in plants and that of crude protein in grain was significantly positive.

[Display omitted] • The continuous planting of Eucalyptus has made the bacterial community unstable. • Eucalyptus bacteria have strong variability across ecological niches. • Ecological niches influence stochastic processes of bacteria in soil and branches. • Ecological issues in management deserve increased attention. The relationship between microorganisms and plants has been a hot topic of research because of its direct link to plant health and productivity, and these interactions are not limited to the soil. The structural and ecological variation of bacterial communities due to spatial isolation in different parts of plants is still unclear. Whether intensive management of Eucalyptus plantations affects this variation should also be concerned. To investigate the mechanisms underlying bacterial changes in different ecological niches of Eucalyptus and the stability of bacterial communities after continuous high-intensity planting of Eucalyptus , we studied the effects of long-term plantation of Eucalyptus on the structure, assembly patterns, and interactions of the bacterial community. Woodlands that planted with Eucalyptus urophylla S.T. Blake × Eucalyptus grandis Hill ex Maiden (Eucalyptus urograndis, hereafter E. urograndis) in three generations (10 years after planting) were selected for study, and the woodlands were cleared and replanted with E. urograndis. Rhizosphere soil, roots, stems, branches, and leaves of E. urograndis differing in age (2, 4, and 6 years) after planting were sampled, and the rhizosphere soil bacteria and endophytic bacterial communities of different parts were determined using the 16S rRNA technique. We detected structural variation in the soil and endophytic bacterial communities as well as variation in community assembly. Stochastic processes made large contributions to the assembly of highly abundant soil bacterial communities, as well as low-abundant endophytic bacterial communities of the branches and leaves (especially leaves), and this pattern may be strongly related to the ecological niches of the bacteria. The bacterial correlation network demonstrated that the properties of Eucalyptus soil and their endophytic bacterial communities can vary 6 years after successive plantings. Thus, measures should be taken to ecologically restore Eucalyptus woodlands after 15 years of high-intensity planting to ensure the stability of microbial community structure, the maintenance of adequate ecological properties during Eucalyptus planting, and the sustainable production and management of Eucalyptus plantations. [ABSTRACT FROM AUTHOR]

Risk assessments of insecticidal Cry proteins from Bacillus thuringiensis (Bt) cotton in soils have been mainly based on microcosm and short-term experiments. There is a lack of longer-term field results, especially when Bt-cotton residues are incorporated into the soil. In this study, we used a six-year field trial to evaluate how cultivation duration and Cry1Ac-inputted modes of Bt-cotton affect the persistence of Cry1Ac proteins and soil microbe-mediated enzymatic properties. The results showed that the persistence of Cry1Ac proteins increased with cultivation duration and periodic residue incorporation of the transgenic Bt-cotton variety ZM41. Moreover, temporal residue incorporation had a relatively larger contribution to the persistence of Cry1Ac proteins in the soil than their release in the growth period. Regardless of Bt-cotton cultivation or residue incorporation, soil microbial biomass was significantly suppressed. However, the dehydrogenase activity was significantly stimulated in Bt-cotton cultivation but suppressed in residue incorporation. The activities of β -glucosidase, nitrate reductase, phosphomonoesterase and arylsulfatase were significantly stimulated in soils with Bt-cotton residue incorporation. Based on a structural equation model analysis, the change in enzymatic activity of these four enzymes was attributed to both a direct effect from Cry1Ac proteins and an indirect effect via dehydrogenase. [ABSTRACT FROM AUTHOR]

• Multi-generational planting of Eucalyptus significantly reduces soil multifunctionality. • Rare rather than abundant microbial communities primarily drive soil multifunctionality in Eucalyptus plantations. • Abundant microbial communities were mainly affected by stochastic processes, while the rare were dominated by deterministic processes. • Soil organic carbon plays an integral role in driving soil multifunctionality in Eucalyptus plantations. • Prolong rotation period and protect rare soil microbial communities to ensure sustainable development of Eucalyptus plantations. Soil multifunctionality not only contributes to the production of ecosystem services (e.g., nutrient cycling, boosts in plant production, and provision of biological processes), but also supports the survival of species (protecting biodiversity) in an ecosystem. Multi-generational planting (sprouting from logging stumps) of Eucalyptus is widely adopted for timber production in southern China, which distinctly induces the decline of soil properties and destroys soil microbial communities. However, research on various Eucalyptus management practices has predominantly concentrated on soil nutrients and microbial populations. The effects of these practices on soil multifunctionality remain unexplored. Furthermore, the underlying mechanisms influencing the abundant and rare microorganisms have not been fully understood. Here, an 18-year Eucalyptus plantation experiment, including single-generation continuous planting (Y18), multiple-generation felling of the same years (D4), and evergreen broadleaf forest control (CK), was designed. Twenty-three parameters associated with soil nutrient cycling were obtained to quantify soil multifunctionality, and partial least squares path modeling (PLS-PM) was used to reveal the main driving force regulating soil multifunctionality. Our results demonstrated that multi-generational Eucalyptus planting significantly reduced soil multifunctionality, microbial diversity, and network stability. Comparatively, single-generational planting showed slight effects on soil multifunctionality and microbial communities. Stochastic processes dominated the assembly of abundant taxa in Eucalyptus plantations, whereas deterministic processes dominated rare taxa. PLS-PM results revealed that soil organic carbon (SOC), dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) directly regulated soil multifunctionality or indirectly through modifying the diversity and networks of rare taxa. The total effect analysis showed that the diversity and network of rare taxa had a greater impact on soil multifunctionality than abundant taxa. SOC and DOC played a crucial role in driving changes in soil multifunctionality. Our findings highlight the need to decrease rotation intensity and conserve rare taxa to mitigate soil quality degradation in artificial Eucalyptus plantations. [ABSTRACT FROM AUTHOR]

Climate change has strong effects on the distribution of soil denitrifying bacterial communities; however, how temperature alter the stability of the abundant and rare denitrifying biosphere remains unknown. In this study, paddy soils were incubated under four temperatures (5 °C, 15 °C, 25 °C, and 35 °C) in 125% water-filled pore space for 96 h and nir S and nos Z genes were then sequenced via high-throughput sequencing. The results showed that both abundant and rare denitrifers responded to varying temperature, however, the abundant taxa were more sensitive. Firstly, for α-diversities of soil denitrifiers, temperature increase affected both abundant and rare taxa by reducing the richness (Chao1 index) of rare taxa and the evenness (Pielou index) of abundant taxa. When the temperature increased from 5 °C to 35 °C, the above indexes decreased about by 30%. However, with regard to community distribution pattern and co-occurrence network, abundant taxa apparently displayed higher sensitivity than rare taxa. Principal co-ordinate analysis (PCoA) indicated an obvious separation of the abundant nirS and nosZ genes with different temperatures, however, the clear separation of the rare taxa was only observed as temperature changed significantly. Bray-Curtis dissimilarity analysis further proved that the community structure differentiation was more significant for abundant taxa under the four temperature conditions. Co-occurrence network analysis revealed that abundant denitrifiers occupied more central locations in the network assembly. More importantly, the edge/node ratio and positive association percentage among abundant taxa increased with temperature increase, implying that abundant taxa possessed more frequent, presumably, more positive interaction under higher temperature. Whereas, the response of the above network topological properties of rare taxa was much weaker. Collectively, these results indicated that increasing temperature significantly affected soil abundant denitrifying taxa by lowering α-diversity, increasing interaction and changing the community structure. Whereas rare taxa were less vulnerable to warming. Accordingly, the abundant denitrifiers could act as "key indicators" to predict the response strategy of soil microorganisms to future global warming, while rare taxa no longer need excessive in-depth analysis. [ABSTRACT FROM AUTHOR]

• Intracellular urease activity increased after urease inhibitors addition. • Intracellular urease activity was positively correlated with ureC abundances. • Bacteria is mainly responsible for intracellular urease production. An incubation experiment was conducted to study the effects of the urease inhibitors N -butyl-thiophosphate triamide (NBPT) and Phenyl-phosphoryl-diamine (PPD) on soil intracellular/extracellular urease activities and bacterial, fungal, and archaea gene (conventional gene and ureC) abundances and their relationships. Urease inhibitors significantly decreased soil extracellular urease while significantly increasing soil intracellular urease activity, and NBPT was more effective in this regard than PPD. During the incubation period, the urease inhibitors significantly increased bacterial 16S rRNA and fungal ITS abundances but had no significant effect on archaea 16S rRNA abundance. The urease inhibitors also significantly increased bacterial ureC abundance and affected the ureC abundance of fungi to varying degrees. A Pearson correlation analysis showed that bacterial 16S rRNA abundance was significantly positively correlated with bacterial ureC abundance, which also suggested a closer relationship between intracellular urease and bacterial gene abundances than between those of fungi and archaea. Our results suggest that after the addition of urease inhibitors decreased extracellular urease activity and had a positive feedback effect on soil microbes, leading to significantly increased abundances of microbial genes, especially ureC , and resulting in increased intracellular urease reserves. Bacteria play a more important role than fungi and archaea in this process. [ABSTRACT FROM AUTHOR]