Intensively managed Camellia oleifera plantations with acidified soil rely on nitrogen (N) fertilizers for high yields, but this accelerates soil acidification and boosts emissions of nitric oxide (NO) and nitrous oxide (N₂O), endangering long-term sustainability. Green manure (GM) serves as an eco-friendly alternative, improving soil fertility and increasing ecosystem carbon and N inputs. However, the effects of GM species, legumes (Leg), gramineous (Gra), and their mixture (Leg-Gra) with residue incorporation on soil acidification and NO/N₂O fluxes remain unclear. To clarify the mechanisms underlying GM intercropping with residue incorporation on soil NO and N₂O emissions, we conducted an in situ study in intensively managed C. oleifera plantation ecosystems intercropping Leg, Gra, and Leg-Gra, or managed with N, manual weeding and natural grass to investigate how GM intercropping with residue incorporation influences soil acidification and NO/N₂O emissions. 1) GM intercropping with residue incorporation reduced both NO and N₂O emission rates compared to N. Specifically, Leg, Gra and Leg-Gra intercropping reduced the emission rates of N₂O by 24.83%, 46.06% and 35.64% compared to N, respectively. 2) GM intercropping reduced the abundance of AOA and AOB genes, increases the abundance of nosZ, and decreases NO and N₂O emissions. 3) Leg-Gra intercropping with residue incorporation increased soil organic carbon (SOC) by 9.96% and raised soil pH to 4.89, representing a 5.81% increase over N treatment. 4) Leg-Gra increased the decomposition rate of leguminous GM, accelerating nutrient release. Legume-gramineous intercropping effectively mitigates soil acidification, enhances SOC, and curbs NO/N₂O emissions, offering a sustainable strategy for acidic agroforestry soils.

While regional climate establishes the hydrothermic baseline for decomposition, inconsistent grazing effects across ecosystems suggest that macroclimatic frameworks alone cannot predict ecosystem sensitivity to contemporary disturbances. We hypothesized that such context-dependent responses are associated with site-specific legacies, defined as integrated functional states shaped by past environmental and management conditions. We conducted a multisite experiment across four temperate grasslands in northern China differing in hydrothermic regimes and grazing histories. Within each site, three-year contemporary grazing treatments were paired with ungrazed controls, and the widespread Leymus chinensis was used as a standardized substrate to isolate decomposition-environment effects. During the 130-day peak decomposition period, decay in ungrazed plots was positively associated with climatic humidity, whereas grazing effects varied among sites: strong inhibition at the historically ungrazed site, promotion at the moderately grazed site, and weak inhibition at heavily grazed and overgrazed sites. Path analysis suggested that regional humidity and grazing history were jointly associated with baseline vegetation and soil properties linked to the decomposition microhabitat. We propose that plant-soil ecological memory provides a useful conceptual filter for interpreting ecosystem responses to contemporary grazing, suggesting that restoration planning should account for historical grazing legacies and prioritize soil-functional recovery in degraded grasslands.

Coastal wetlands are experiencing long-term plant invasions, which pose a significant impact on the soil microbiome. However, the latitudinal diversity patterns of soil microbiome in blue carbon ecosystems under plant invasion remain poorly understood. In this study, 12 sample sites spanning over 2000 km were established along China’s coastlines, with paired mudflat and Spartina alterniflora-invaded habitats. Soil (mudflat sediments included, termed “soil” for consistency) bacterial diversity was assessed across topsoil, subsoil, and deep soil layers. In mudflat habitats, bacterial richness generally increased with latitude. In contrast, S. alterniflora invasion altered this pattern to a hump-shaped distribution. This shift was most pronounced in the topsoil compared to the subsoil and deep soil layers, a consistent trend across the dominant taxa. Additionally, plant invasion accelerated the spatial turnover of bacterial communities in the topsoil, but not in deeper layers. Environmental variables, including soil temperature and salinity, were the predominant factors shaping these latitudinal diversity patterns. Structural equation models revealed that soil temperature, rather than soil depth, was the primary direct driver of bacterial richness, and plant invasion reduced the influence of soil depth on this relationship. Overall, our study revealed that invasive plant regimes profoundly restructured the latitudinal diversity pattern of soil microbiomes, particularly in the topsoil. This study broadens our understanding of how plant invasion affects soil microbial biogeography and its underlying drivers in blue carbon ecosystems.

Climate-driven shifts in soil fauna may strongly affect soil functioning in mountain forests, yet their consequences remain poorly understood. In a microcosm experiment, we simulated upslope migration by introducing low-altitude communities of oribatid mites and Collembola from a coniferous-broadleaf mixed forest (migrant communities) into coniferous forest soil containing native high-altitude communities, either separately or together. We assessed treatment-induced changes in soil functioning by combining gas chromatography-based measurements of greenhouse gas (GHG) emissions with high-throughput sequencing of microbial communities and an evaluation of ecosystem multifunctionality (EMF). Relative to the mesofauna-free control, native mesofauna increased CO₂ and N₂O emissions by 71.33% and 252.19%, respectively, and enhanced EMF by 26.02%. When native and migrant communities co-occurred, cumulative CO₂ and N₂O emissions were 36.18% and 26.08% lower than expected from additive expectation based on their individual effects, suggesting strong non-additive interactions between migrant and native communities. These functional changes were accompanied by shifts in microbial community assembly, with contrasting responses between bacterial and fungal communities. Random forest models further indicated that mesofaunal diversity explained more variation in CO₂ and N₂O emissions, as well as EMF, than the measured microbial variables. Overall, our findings highlight soil mesofaunal community dynamics as an important predictor of functional changes in mountain coniferous forest soils under climate-driven range shifts.

Soil gaseous nitrogen (N) losses, including nitric oxide (NO), nitrous oxide (N₂O) and dinitrogen (N₂), constitute an important component of ecosystem N budgets and strongly influence climate change. However, precisely distinguishing their highly complex production pathways remains a major challenge. Stable N isotope techniques, including ¹⁵N tracing and natural-abundance isotopocule approaches, provide critical tools for disentangling these pathways. Over the past two decades, Chinese researchers have developed and refined four major isotope-based source-partitioning methods, mainly including the three-pool source partitioning approach based on paired ¹⁵N labeling of NH₄⁺, NO₃⁻, and organic N, the combined ¹⁵N paired-labeling and isotope-pairing technique, the ¹⁵NO₃⁻ labeling and pairing approach coupled with nitrification inhibitors, and the N₂O isotopocule site preference (SP) approach. These approaches have been applied in forests and croplands, improving understanding of the relative contributions of denitrification, nitrification, heterotrophic nitrification, codenitrification, and anammox to gaseous N production. This review summarizes the principles, designs, strengths, limitations, and applications of these four N isotope approaches in Chinese ecosystems, highlighting contributions of Chinese researchers to methodological innovation and in situ applications, and providing a China-based perspective for global studies of soil gaseous N losses and methodological support for N cycle model optimization and mitigation strategies.

Plastic pollution, a defining symptom of our planet’s unsustainable linear “take-make-dispose” economy, presents a critical challenge to ecosystem health and sustainable development. Terrestrial ecosystems, particularly soils, have become the primary sink for microplastic contamination, where these pollutants form novel “Soil Plastisphere” habitats that disrupt essential biogeochemical cycles and threaten soil integrity. This cross-disciplinary, synthetic review assesses the potential of microbial biodegradation as a key biotechnological tool for sustainable plastic waste management and the development of a circular economy. We first evaluate the variable impacts of the plastisphere on soil health, providing a crucial baseline for understanding the ecological risks and informing sustainability policies. We then examine the core biochemical pathways of plastic degradation, highlighting the remarkable diversity of novel catalysts—such as thermophilic PETases, cutinases and the crucial extracellular oxidoreductases secreted by fungi to initiate the breakdown of recalcitrant polymers—discovered through metagenomics. Finally, we survey the frontier of biotechnology, reviewing advanced strategies that move beyond simple degradation, such as the rational engineering of hyper-efficient enzymes, the development of reusable whole-cell biocatalysts, and the “upcycling” of plastic waste into valuable bioproducts—including polyhydroxybutyrate (PHB). Despite these advances, critical knowledge gaps remain, particularly regarding the enzymatic cleavage of highly recalcitrant polyolefins and the translation of laboratory-scale successes to complex field conditions; overcoming these bottlenecks will be essential for developing robust, biologically-based solutions within a circular materials economy.

Biochar has emerged as a promising carrier for microbial inoculants, yet its capacity to enhance inoculant persistence while preserving native soil microbial communities remains insufficiently documented. This study evaluated an olive-pomace-derived biochar as a carrier for Bacillus velezensis and Trichoderma virens in a Mediterranean Cambisol under controlled conditions. Biochar supported high initial microbial loadings (>10⁸ CFU or spores g⁻¹ biochar), strong short-term viability (76–88%), and clear colonization of pore surfaces as observed by scanning electron microscopy. Following a 30-day pot incubation, biochar-based inoculation enhanced microbial persistence compared with direct soil application, maintaining recoverable inoculant populations close to or above initial levels. Findings revealed that biochar maintained community-level structural and functional patterns at the resolution detectable by fingerprinting and metabolic profiling approaches. These results suggest that biochar functioned primarily as a physical carrier, providing protected microsites that may have contributed to the stabilization of introduced microorganisms while maintaining overall soil functional diversity. Our findings demonstrate that olive-pomace biochar can be valorized as an effective microbial carrier, suited to Mediterranean soils where early inoculant establishment is often constrained. Future research should assess the durability of these mechanisms under field conditions to determine their long-term relevance for soil biological functioning and restoration.

Agricultural intensification over the 20th century has increased crop yields but has also led to substantial environmental impacts, including greenhouse gas (GHG) emissions and declining soil quality. Crop diversification is increasingly viewed as a sustainable strategy to improve soil health and mitigate GHG emissions. This study presents a bibliometric analysis of global research trends on crop diversification for soil carbon (C) sequestration and GHG mitigation from 1979 to 2024. A total of 9036 articles were analyzed, revealing a substantial increase in research output since 2010, marking a key turning point in the field. Key contributing nations, including the United States and China have driven this surge in interest. Co-occurrence and keyword analyses revealed four major research clusters: soil health and sustainable tillage systems, agricultural management practices and cropping systems, analytical methods and assessment, GHG emissions and mitigation strategies. Long-term field experiments and models were identified as critical methodologies in studying soil C dynamics and GHG emissions. We also summarized the underlying mechanisms by which diversified cropping enhances soil carbon sequestration while mitigating greenhouse gas emissions. This review highlights the growing importance of crop diversification for sustainable agriculture and provides future research directions in soil management and GHG mitigation.

Land-use change is increasingly altering the structure and function of soil fauna. However, how forest conversion shapes the functional composition and diversity of soil nematode communities is still poorly understood in subtropical forests. This study investigated the response of soil nematode communities to the conversion of natural forests into chestnut (Castanea henryi) plantations, with particular attention to the role of slope aspect in subtropical forest ecosystems. Our results showed that converting natural forests into chestnut plantations led to a pronounced reduction in soil nematode density, diversity (Shannon–Wiener index), and genus richness by 67.6%, 12.2%, and 24.4%, respectively, particularly on north-facing (shady) slopes. Additionally, soil nematode co-occurrence networks in chestnut plantations were reduced robustness compared with natural forests by 60.7%. South-facing (sunny) slopes increased total nematode and omnivore-predator abundance by 36.9% and 71.9%, respectively, and amplified the negative impact on herbivorous nematodes from land conversion. These findings emphasize the critical role of considering slope aspect in chestnut plantation management to mitigate negative impacts on soil nematode communities and maintain soil health in subtropical forests.

Microbial life-history strategies are fundamental to predicting community assembly and ecosystem function, yet they are often distilled to a single axis—the copiotroph-oligotroph continuum—that couples fast growth with large genomes and slow growth with small genomes. Whether this one-dimensional view captures the full diversity of bacterial strategies in soil remains untested at population level. Here, we couple genome-resolved metagenomics with trait-based inference to examine how genome size and maximum growth rate—two core life-history traits—co-vary across 321 bacterial populations from 67 soils spanning gradients in pH and organic carbon. We find that genome size and growth rate are only weakly correlated, allowing the identification of four contrasting life-history strategy groups defined by extreme combinations of genome size and growth potential: Small-Fast, Small-Slow, Large-Fast, and Large-Slow. Genome size is strongly phylogenetically conserved and defines the breadth of functional potential, whereas growth rate is more evolutionarily labile and differentiates strategies through targeted investments in biosynthetic pathways (e.g., amino acid metabolism). Environmental filtering shapes specific strategy combinations rather than single traits: compact genomes with high growth potential (Small-Fast) are selected in alkaline, low-carbon soils, while the Large-Slow strategy characterized by expanded genomes with slow growth shows elevated relative abundance in acidic, carbon-rich soils relative to alkaline, low-carbon conditions. Our findings challenge the prevailing copiotroph-oligotroph continuum by demonstrating that bacterial life-history strategies are inherently multidimensional. By decoupling genome size from growth potential, this framework provides a more predictive basis for understanding how environmental filtering shapes microbial life-history strategies and functional potential across soil ecosystems.

Drylands are crucial to global biogeochemical cycles, yet the linkages between soil multifunctionality (SMF) and microbial diversity, community assembly, and network architecture remain poorly understood. Here, we investigated these relationships across three grassland types—desert steppe, temperate desert, and temperate steppe—in the drylands of Kazakhstan. Despite contrasting environmental conditions, microbial α diversity did not differ significantly among grassland types and was more strongly associated with climatic factors than with grassland type per se. Fungal and bacterial communities exhibited distinct assembly patterns. Fungal communities were governed by dispersal limitation (57.46%–57.69%) and homogeneous selection (13.16%–16.40%), with community similarity correlated with both environmental and geographic distances. In contrast, bacterial communities were shaped predominantly by ecological drift (40.38%–42.88%), and their similarity was linked primarily to geographic distance. Microbial co-occurrence network also varied systematically across grassland types, shifting from more modular structures in desert steppe to more connected configurations in temperate desert and temperate steppe. Structural equation modeling showed that climatic variables, particularly mean annual temperature, exerted the strongest direct effects on SMF, whereas community assembly processes influenced SMF only indirectly through their regulation of microbial diversity. Overall, climatic gradients, rather than microbial richness per se, emerged as the primary correlates of SMF, with fungal and bacterial communities exhibiting divergent assembly processes and network organization along the aridity gradient. These findings provide an integrative, association-based framework for understanding how environmental gradients related to aridification correspond to microbial ecological organization and SMF in drylands.

Through the input of carbon (C), nitrogen (N), and phosphorus (P), biochar can alter the stoichiometric imbalance between available resources and microbial elemental demands, thereby influencing microbial metabolism. However, how biochar affects microbial C use efficiency (CUE) and its linkage with microbial respiration across different feedstocks remains unclear. This study investigated the impacts of biochars (from pig manure (MB), peanut shell (PB), corn straw (CB), bamboo (BB), and wood (WB)) on soil microbial respiration, enzyme activity, and CUE estimated by an ¹⁸O-H₂O labeling approach (CUE-¹⁸O) and an ecoenzyme stoichiometry model (CUE_C:N or CUE_C:P) in a P-limited forest soil. Over 120 days, MB and PB biochars enhanced microbial respiration and biomass C, while other biochars had weak effects on them. MB and PB treatments significantly increased soil P availability and decreased C:P imbalances. Moreover, MB and PB alleviated microbial P limitation and increased CUE-¹⁸O and CUE_C:P. Partial least squares path modeling indicated that decreased C:P imbalance and microbial P limitation contributed greatly to microbial respiration via enhancing microbial CUE_C:P rather than CUE-¹⁸O. Overall, our findings underscore the critical role of biochar feedstock in regulating short-term microbial C metabolism, providing insights for the understanding of the effects of biochar on soil C flux in P-limited forest soils.

Nitrogen-fixing legumes such as Robinia pseudoacacia are widely used in vegetation restoration due to their rapid growth and N-fixation capacity. However, large-scale single-species forests of N-fixing species often lead to long-term unsustainability, such as functional simplification and soil desiccation. Mixed-species forests that integrate N-fixing trees with native drought-tolerant species may help overcome these limitations, but their effects on soil functional microbial communities and nutrient cycling remain poorly understood. This study examined the 24-year effects of mixed plantations combining Robinia pseudoacacia with native species (Prunus sibirica, Platycladus orientalis, and Pinus tabuliformis) on soil microbial functional diversity and gene assembly processes based on metagenomic functional profiles, and explored their relationships with soil multi-nutrient cycling. Compared to monocultures, mixed-species forests exhibited significantly higher microbial functional α-diversity (gene richness and Shannon index) and soil multi-nutrient cycling index, with the most pronounced effects in mixed-species forests combining Robinia pseudoacacia with Pinus tabuliformis. Mixed plantations also exhibited more diverse functional gene compositions and higher abundances of genes associated with nutrient cycling processes, including carbon decomposition, aerobic respiration, fermentation, carbon and nitrogen fixation, nitrification, organic phosphorus mineralization and inorganic phosphorus solubilization. Spatial and environmental distance-decay relationships of functional gene composition were more pronounced in monocultures than in mixed-species forests. In contrast, gene assembly in mixed-species forests was more strongly influenced by stochastic processes, reflecting greater variability in functional composition and reduced environmental constraint. Furthermore, the richness of core genes in the functional network was a strong determinant of soil multi-nutrient cycling in mixed-species forests, highlighting the pivotal role of these keystone functions in sustaining biogeochemical processes. These findings emphasize that microbial functional communities should be prioritized in evaluating the ecological consequences of afforestation and provide guidance for optimizing mixed-plantation design to enhance soil function and ecosystem sustainability.

Soil priming effect (PE) and microbial carbon use efficiency (CUE) are key drivers of soil carbon (C) cycling, yet their regulatory mechanisms remain unclear in coastal saline soils with high salinity and limited organic C. In this study, ¹³C-labeled maize straw was used as a standardized exogenous organic material in a 180-day incubation experiment to trace microbial C transformation processes in coastal saline soils of the Bohai Rim, China. The effects of a salinity gradient (low, medium, high) on PE and microbial CUE were evaluated, and the influence of increased C availability via field straw return on these parameters was also examined in low- and medium-salinity soils. The study showed that soil salinity reduced microbial biomass C (MBC) and the activities of C-, nitrogen (N)-, and phosphorus (P)-transforming enzymes, resulting in a negative linear relationship between microbial CUE and salinity. Straw return further decreased MBC and extracellular enzyme activities in low-salinity soils, leading to a 22.25% decline in CUE, whereas no significant changes in MBC or CUE were observed in medium-salinity soils. The PE exhibited a non-linear, threshold-like response to salinity: under low-salinity conditions, PE was primarily controlled by SOC availability, whereas under high-salinity conditions, the physical protection of SOC was compromised, promoting C mineralization. In the short term (20 days), straw return significantly suppressed PE in low-salinity (by 37.24%) and medium-salinity (by 65.58%) soils, likely due to enhanced SOC physical protection (as indicated by a significant decrease in the labile organic C (LOC):SOC ratio) and total N (TN) accumulation following straw return. Overall, this study demonstrates that while salinity determines microbial C metabolism and PE, the effects of straw return are salinity-dependent, suggesting that organic matter management in coastal saline soils should consider both salinity conditions and straw application strategies to optimize C sequestration.

Microplastics (MPs) are recognized as emerging contaminants that facilitate the dissemination of antibiotic resistance genes (ARGs). However, the ecological mechanisms underlying MP-induced changes soil antibiotic resistance, particularly those mediated by the soil food web, remain largely unexplored. To address this knowledge gap, we conducted a microcosm experiment to investigate how biodegradable MPs (bio-MPs) of different particle sizes influence soil antibiotic resistance through their effects on the soil micro-food web. The results showed that the abundances of functional genes associated with bio-MPs biodegradation were significantly higher in soils amended with 20 μm bio-MPs than in those amended with 300 μm bio-MPs. The biodegradation of 20 μm bio-MP significantly increased the diversity and abundance of ARGs while altering their composition, particularly through the enrichment of genes conferring resistance to multidrug, tetracycline, and aminoglycoside. The tetracycline resistance gene tetA(48), the multidrug resistance gene ompR, and the unclassified resistance gene VanR were the three most abundant ARG subtypes and were significantly enriched in soils amended with 20 μm bio-MPs. Furthermore, amendment with 20 μm bio-MPs significantly increased the total abundance of mobile genetic elements (MGEs), which was positively correlated with ARG abundance. Additionally, amendment with 20 μm bio-MPs enriched Psedomonadota, the predominant hosts of ARGs. Furthermore, bio-MPs destabilized the soil micro-food web, and its stability was negatively associated with ARG abundance. Collectively, these findings suggest that multi-trophic interactions within the soil micro-food web play a previously underappreciated role in regulating antibiotic resistance responses to plastic pollution in soil ecosystems.