Nitrite-dependent anaerobic methane oxidation (n-damo), performed by the bacteria associated with Candidatus Methylomirabilis oxyfera, acts as a novel methane sink in coastal wetlands. Conversion of coastal wetlands into paddy fields is a common land-use change that has profound effects on methane emissions, but its impact on n-damo process is nearly unknown. Our study adopted a space-for-time substitution method to compare n-damo activity and community of Methylomirabilis-like bacteria between natural vegetation covered by Phragmites australis, Kandelia candek, or Bruguiera sexangula and adjacent converted paddy fields in six China’s coastal wetlands. Generalized linear mixed model indicated that the activity of n-damo significantly increased by 43.6% and 165.8% after conversion of K. candek and B. sexangula wetlands into rice paddies, respectively, while the activity exhibited no significant change after conversion of P. australis wetlands. Furthermore, the abundance of Methylomirabilis-like bacteria significantly increased by 90.2%, 210.0%, and 110.1% following the conversion in wetlands covered by K. candek, B. sexangula, and P. australis, respectively. Principal co-ordinates analysis revealed significant changes in community structure of Methylomirabilis-like bacteria among vegetation types, with K. candek and B. sexangula showing a greater divergence than P. australis when compared to respective paddy fields. Path analysis indicated that land conversion resulted in changes in soil moisture content, organic carbon content, bulk density, and salinity and further affected the abundance of Methylomirabilis-like bacteria and ultimately n-damo activity. Overall, this is the first study to reveal the impact of conversion of coastal wetlands into paddy fields on n-damo activity and Methylomirabilis-like bacteria, and the impact was closely associated with the original native plant types. The results can enhance our understanding of the microbial-driven mechanisms of the impact of land conversion on methane emissions.

Organic mulching is widely applied in agricultural and forest ecosystems to improve crop yields and maintain soil quality. However, its long-term impact on soil organic carbon (SOC) stability and the underlying mechanisms remain unclear. An in situ experiment was initiated in 2018 in the subtropical region of China, with the non-mulched treatment serving as the control group (0 year of mulching), to investigate the effects of mulching on the organic carbon components (particulate organic carbon, POC, and mineral-associated organic carbon, MAOC) in Phyllostachys praecox bamboo forests across different mulching durations of 1, 3, and 5 years. Our results indicated that five-year mulching decreased soil POC concentration by 13.36%, while increasing MAOC and SOC by 130.3% and 64.53%, respectively, compared to no mulching. The POC/MAOC ratio dropped, indicating improved SOC stability. Additionally, soil pH decreased with mulching duration, while bacterial and fungal diversity, available phosphorus content, and β-xylosidase activity significantly increased. Structural equation modeling indicated that POC was mainly regulated by available phosphorus and fungal communities. While MAOC was affected by soil pH, which also mediated its response by influencing enzyme activity and bacterial diversity. In bamboo forest ecosystems, long-term organic mulching enhances SOC sequestration and stability, providing insights into SOC management for sustainable forestry. Such information indicates continuous mulching can be used to improve SOC sequestration in subtropical bamboo ecosystems.

Elucidating the intricate dynamics of microbial communities across soil profiles is essential for deciphering the mechanisms by which microorganisms regulate ecosystem functions. However, previous studies on soil microorganisms have predominantly centered on abundant taxa, neglecting the significant role of rare taxa in maintaining ecosystem functions. This study comprehensively analyzed the diversity and assembly processes of both rare and abundant microbial taxa in the profiles of Udic and Ustic Isohumosols in northeast China. We also explored the relative contribution of rare and abundant microbial taxa in maintaining ecosystem multifunctionality. Results showed that rare microbial taxa exhibited a higher diversity compared to abundant taxa, and rare microbial taxa occupied more central positions within networks. Furthermore, rare taxa displayed narrower ecological niche breadths and stronger phylogenetic signals, and their community assembly was predominantly governed by deterministic processes. In contrast, stochastic processes exert more pronounced influences on the assemblage of abundant taxa. Ecosystem multifunctionality was significantly reduced in deep soil horizons relative to the surface soil horizons. This is accompanied by close cooperation of microorganisms to cope with environmental stress in deep soils. This study highlights the pivotal role of rare microbial communities in shaping multifunctionality of ecosystems across the entire soil profiles.

The alkaline phosphatase (phoD) gene-encoding bacterial communities (phoD-harbouring communities, hereafter) play crucial roles in organic phosphorus (Po) mineralisation across global terrestrial ecosystems. However, their geographic distribution and driving factors remain unclear, largely due to the mosaic temperature and humidity patterns and the lack of comprehensive high-resolution sampling data across the Qinghai-Tibet Plateau. We addressed this gap using amplicon sequencing techniques and analyses of soil properties as well as plant biomass. Plant biomass, soil organic carbon (C), Po content, C:P ratio, alkaline phosphatase (ALP) activity, and the richness and abundance of key soil phoD-harbouring taxa were higher in warmer, more humid regions, such as the southeastern plateau than the northeastern plateau, while soil pH followed an inverse trend. Soil pH and Po content emerged as the key factors shaping the geographic distribution of phoD-harbouring communities. Acidic soils were associated with higher C:P ratios, community richness, ALP activity, and Po content than alkaline soils. Our findings suggest that warmer, more humid regions promote soil acidification, which in turn drive changes in phoD-harbouring communities, enhance ALP activity, and stimulate Po mineralisation. This study provides new insights into the geographic distribution of phoD-harbouring communities and their role in Po mineralisation across the Qinghai-Tibet Plateau.

This study examines the effects of different organic carrier materials, chicken manure, mill mud, and cow manure on the long-term viability and metabolite profiles of rhizobacterial strains Mesorhizobium sp. and Rhizobium sp. Over one year, growth curve analysis revealed significant differences in bacterial proliferation. Mill mud supported the most robust growth, with a doubling of 11 days, compared to chicken and cow manure, which exhibited growth saturation after five to eight months. Non-targeted ¹H-NMR metabolite profiling revealed distinct sugar and amino acid profiles across carriers. Mill mud exhibited a broader range of sugars, including sucrose, maltose, and mannose, while chicken and cow manure primarily contained monosaccharides like glucose, xylose, and mannitol. Amino acids such as lysine and glutamate were higher in chicken manure, followed by cow manure and mill mud. Plant growth-promoting metabolites were detected in all carriers, with Mesorhizobium sp. and Rhizobium sp. enhancing their production by up to 200% in mill mud and cow manure. Both bacterial strains utilized sugars from the carriers, with Mesorhizobium sp. showing more consistent sugar metabolism. These findings suggest that mill mud is an effective carrier for sustaining rhizobacterial viability and enhancing metabolite production, benefiting biofertilizer formulations and soil health.

The upward shift of the alpine treeline driven by global climate change has been extensively observed across many mountain ecosystems worldwide. However, variations in belowground microbial communities in the treeline ecotone, as well as the influence of microtopographic factors (e.g., slope aspect) on these changes, remain unclear. Here, we collected soil samples from different aspects above or below the treeline and analyzed the microbial communities using high-throughput sequencing. Our study revealed distinct community characteristics, co-occurrence patterns, and assembly processes between bacterial and fungal communities. Especially, homogeneous selection and dispersal limitation played dominant roles in shaping bacterial and fungal communities, respectively. Keystone bacteria were more critical for maintaining network stability above the treeline, while fungi were the keystone taxa for network stability below the treeline. We also found that oligotrophic species such as Acidobacteriota, Chloroflexi, Verrucomicrobiota, and Ascomycota were predominantly enriched above the treeline, whereas copiotrophic species like Proteobacteria, Gemmatimonadota, Actinobacteriota, and Firmicutes were more abundant below the treeline. Our results uncovered that microbial communities responded greatly to treeline shift than slope aspect, and also imply that the upward shift of the alpine treeline may increase the stochasticity of microbial communities. These findings facilitate our understanding of how microbial communities in the treeline transition zones of alpine ecosystems respond to global warming and their potential effects on soil carbon dynamics.

The transformation of mountainous karst forests into urban parks requires a detailed evaluation of its impact on existing ecosystems, particularly in terms of the interplay between soil characteristics and plant diversity. In this study, we examined the species diversity of woody plants and soil characteristics within three established urban parks in Guiyang, China. We analyzed how habitat modification and the age of these parks influence soil properties and the diversity of woody plants. Our study revealed that soil levels of organic carbon, nitrogen, phosphorus, and potassium in artificial green spaces were significantly lower than in remnant forests. Woody plant alpha-diversity exhibited a negative correlation with potassium in remnant forests, but with phosphorus in artificial spaces. Interestingly, the associations between plant α-diversity and soil organic carbon and nitrogen were not significant in older parks, but were evident in newer ones. Furthermore, nitrogen, phosphorus, and potassium content significantly influenced woody plant composition across these parks. Habitat type and soil properties impacted the compositional diversity of woody plants more than park age, with phosphorus exerting the most substantial effect. In order to balance human recreational activities with the conservation of native ecosystems, it is essential to develop strategic management plans that prioritize soil enrichment and the maintenance of biodiversity in urban mountain parks.

Granulating fluffy straw into high-density particles is an innovative approach for uniformly incorporating straw into plough layers. However, massive granulated straw incorporation probably causes microbial nutrient limitation, decreasing straw-C accrual and crop yield. Whether nutrient supplement increases straw-C accumulation remains unclear. In this study, we conducted one-year of micro-plot experiments incorporating massive granulated straw with initial C:N ratio (GS) and adjusted the C:N ratio by nutrient supplement (GS_N) in infertile upland and paddy. After one year,GS incorporation greatly improved the surface (0–20 cm layer) soil organic C by 91% and 80% in upland and paddy, respectively, compared to their control. In upland, GS led to lower lignin phenols but higher amino sugars than paddy owing to its stronger microbial anabolism. In upland, GS_N incorporation decreased soil organic C by 11.3% than GS by reducing lignin phenols and amino sugars. However, GS_N incorporation increased organic C by 2.2% in paddy, via promoting microbial necromass accumulation. GS_N incorporation improved crop yield by 26.6% in upland and 12.0% in paddy than GS. Collectively, granulated straw incorporation effectively enhances organic C and crop yield but that responses to nutrient supplement depend on soil properties. Tailored nutrient management is crucial to optimizing C sequestration and productivity in diverse soils.

Labile organic carbon (LOC) plays a pivotal role in soil biogeochemistry and ecological functions. China’s coastal wetlands have been profoundly impacted due to plant invasion and land use change, but the effects on soil LOC quantity and composition are unclear. This study analyzed the soil LOC components—namely, dissolved organic carbon (DOC), easily oxidizable carbon (EOC), and microbial biomass carbon (MBC)—across twenty-one coastal wetlands in southeastern China. These wetlands underwent a uniform land cover transition from native mudflats (MFs) to Spartina alterniflora marshes (SAs), and eventually to aquaculture ponds (APs). The results indicated that EOC was the dominant component of soil organic carbon (SOC) (57.5%–61.6%), followed by MBC (3.5%–4.5%) and DOC (<0.5%). The transition from MFs to SAs led to a rise in mean EOC and DOC by 18.6% and 41.4%, respectively. Subsequent conversion of SAs to APs resulted in a reduction in mean EOC and DOC by 5.9% and 20.3%, respectively. MBC did not differ significantly among habitat types. Total nitrogen availability was the main driver of changes in LOC across both land cover change scenarios. The mineralization rate of SOC were more strongly correlated with DOC than EOC and MBC. Microbial turnover of EOC was temperature dependent across the geographical range. These finds highlighted that plant invasion and land use change affected LOC fractions and subsequent SOC stability and carbon emissions in coastal wetlands.

The objective of this study was to investigate the combined effect of soil amendments and pest attack on plant-induced defense and their impact on a biological control agent’s behavior. The effects of olive mill wastes revalorized through vermicomposting on the aboveground tri-trophic interactions among olive trees (Olea europaea), the olive seed-feeder, Prays oleae, and its natural predator, Chrysoperla carnea, were evaluated. The findings demonstrate that soil nitrogen and organic carbon levels, in conjunction with fungal diversity and functionality within olive roots, exert a significant influence on the volatile compounds emitted by the plant underattack that are most appealing to C. carnea. Moreover, the attractivenessof aerial volatiles was found to correlate with soil organic carbon content and the taxonomic and functional diversity of both bacteria and fungi in the olive root system. It is worthy of note that three particular volatile compounds, namely 5-hepten-2-one-6-methyl, acetic acid and nonanal, were consistently observed to attract C. carnea. These findings highlight the potential of soil amendments to enhance biological control strategies. Future research should prioritise the validation the greenhouse findings through large-scale field trials and the assessment of the practical applications of soil amendments in pest management programmes.

A range of land management practices are available to achieve better soil quality, but their combined effects remain understudied. We hypothesize that more diverse management practices, meaning higher dissimilarity, lead to stronger effects on soil functions and properties. Eight practices (biochar, compost, clay, amorphous silica, basalt, microbial inoculum, reduced physical disturbance and organic matter diversity) were selected with 20 replicates for treatments involving 2, 4, or 6 factors and 10 replicates for 8 factor treatments. We investigated the impact of individual factors, factor number, factor dissimilarity and factor composition on soil respiration, soil enzymatic activities (β-glucosidase, β-D-cellobiosidase, β-N-acetylglucosaminidase and phosphatase), soil pH, water stable aggregates and permanganate oxidizable carbon fraction. By including dissimilarity in addition to factor number, variance explained for soil respiration and enzymatic activities increased up to 54.21%. For soil pH and water-stable aggregates, explained variability increased to 65.57% and 57.38%, respectively. More diverse management practices boosted soil microbial activities, enhanced soil aggregate stability, improved soil pH while reducing labile carbon, whereas factor number only influenced water stable aggregates and soil pH. Our study highlights the importance of management practices diversity in soil functions and properties and calls for further research on synergistic combinations of diverse interventions.

The soil nitrogen (N) supply plays a core role in nutrient cycling, whereas phosphorus (P) is generally considered the limiting element of ecological processes in subtropical forests. However, the specific characteristics and regulatory mechanisms governing how P affects soil N mineralization remain incompletely understood. P fertilizer is often applied in bamboo forests, and we collected bulk soil and two types of rhizosphere soils (soils surrounding stump roots and rhizome roots, respectively) from a bamboo forest and conducted microcosm experiments with P addition (PA) to simulate the application of P fertilizer. The N mineralization and microbial and enzymatic parameters of the rhizosphere and bulk soils presented the same response to PA. PA increased the rate of net N mineralization and ammonification, suggesting that PA is beneficial to the N supply in the soil. PA increased the soil bacterial biomass but decreased the fungi:bacteria ratio. The soil enzyme C:N:P ratio indicated that the microbial community was subjected to P limitation. PA resulted in an increase in the enzyme C:P and N:P ratios and a decrease in the enzyme vector angle, suggesting alleviation of P limitation in the soil microbial community. Hierarchical partitioning and Pearson correlation analyses revealed that enzymatic stoichiometry and the vector angle were key regulators of soil N mineralization. These results indicate that PA can not only increase the concentration of soil P but also enhance the soil N supply in subtropical P-limited forests, primarily through changes in microbial nutrient limitation rather than in microbial biomass or community structure.

The application of nitrification inhibitors (NIs) and crop straw with nitrogen (N) fertilizers is a common practice aimed at enhancing soil N conservation and improving crop N use. However, their effects on gaseous N emissions from soils, particularly for N₂, are less understood. We conducted a 60-day soil incubation experiment under controlled conditions (80% water-filled pore space and 25°C) to investigate the effects of NI or maize straw application on N₂O and N₂ emissions from two typical upland soils: a Mollisol and an Inceptisol, which have contrasting pH values. Both soils were fertilized with ¹⁵N-labeled urea. During the incubation period, cumulative N₂O and N₂ emissions for the urea-only treatment in the Mollisol were 0.5 and 12 mg N kg^‒1 soil, respectively, while emissions in the Inceptisol reached 15 and 176 mg N kg^‒1. The application of NI (dicyandiamide) reduced N₂O emissions by 66%‒72% in both soils and decreased N₂ emissions by 81% in the Inceptisol, although it increased N₂ emissions by 15% in the Mollisol. Straw application also reduced N₂O emissions by 60% in the Mollisol and by 4% in the Inceptisol, but it increased N₂ emissions by 75%‒96% in both soils. Notably, the increased N₂ emissions following straw incorporation were primarily soil-derived rather than fertilizer-derived in both soils. These findings reveal that the applications of NIs or straw have varying impacts on N₂O and N₂ emissions across different soils, and that NI application could be a promising strategy to reduce high gaseous N losses in Inceptisol following N fertilization.

Biogeographic patterns of microbial communities in wetland soils at broad scales remain underexplored compared to those in well-drained soils, particularly regarding abundant and rare taxa. Here, we investigated the ecological distributions and assembly mechanisms of abundant and rare bacterial sub-communities and explored their underlying environmental drivers in inland wetland soils across eastern China. Both bacterial sub-communities exhibited significant distance-decay relationships (DDR), with a stronger DDR observed for abundant sub-communities due to more pronounced environmental filtering and dispersal limitation. Deterministic processes predominantly governed bacterial communities (62%‒97%), while stochasticity played a larger role in rare sub-communities (38%) compared to abundant ones (4.0%). Soil pH emerged as a dominant factor influencing bacterial communities and mediated the assembly of both sub-communities. The diversity of overall and rare taxa increased with pH and peaked at pH of 8.31, followed by an abrupt decline, suggesting a threshold effect on their ecological distributions. When pH exceeded 8.31, bacterial communities rapidly converged to more deterministic assemblages (especially for abundant taxa), with decreased species coexistence and increased negative cohesion (i.e., reflecting the degree of competition), suggesting intensified niche-based exclusion among bacterial communities. Collectively, this broad-scale study provides new insights into pH-related rules governing wetland bacterial biospheres and underscores the distinct biogeographic patterns between abundant and rare bacteria. The abrupt threshold of soil bacteria identified can inform effective adaptation and conservation efforts to sustain wetland ecosystem functioning.

The application of silicate rock powder to agricultural soils is a promising strategy for atmospheric CO₂ removal. However, most research focuses on inorganic carbon sequestration via enhanced rock weathering, overlooking its impact on soil organic carbon (SOC) decomposition, which is essential for quantifying net CO₂ removal. To address this gap, we conducted a 233-day incubation experiment to investigate the impact of wollastonite powder on soil CO₂ emissions, SOC decomposition, pH, and cation concentrations across three agricultural soils with pH levels of 4.4, 5.6, and 7.7. Results showed 89.0% and 74.4% rock powder weathering in the most acidic and alkaline soils, respectively. In acidic soils, wollastonite powder addition increased CO₂ emissions due to the release of intrinsic CaCO₃ containing in wollastonite or/and SOC. However, these CO₂ emissions accounted for less than 20% of the total CO₂ removal by wollastonite weathering. In contrast, alkaline soils experienced a reduction in CO₂ emissions with wollastonite powder amendment. Net CO₂ removal for soils with pH 4.4 and 7.7 were 1.0 and 1.1 g C kg⁻¹ soil, respectively. This study confirms that wollastonite weathering is effective for CO₂ mitigation regardless of soil pH.