Search Results (4,799)

Sequence-based tools have greatly improved the molecular description of soil bioremediation, but detection alone cannot confirm that a contaminant is being degraded by a defined pathway. In soils, bioavailability limitations, redox microsites, relic DNA, gene mobility, and community restructuring can decouple gene presence from reaction flux. This review synthesizes an operational framework that separates three inferential levels: pathway potential, in situ activity, and verified pathway operation. The framework links inoculant fate, functional gene abundance, gene expression, pathway reconstruction, stable isotope probing, and targeted chemical analysis under explicit quality assurance, quality control, and decision rules. Particular attention is given to distinguishing parent compound loss from mineralization and detoxification and to using isotopic attribution when functional redundancy or inoculant-native overlap obscures agency. Instead of being presented as conceptually new, these principles are organized into a practical workflow for soil systems. This structure clarifies what can be discerned from genes, transcripts, proteins, metabolites, and transformation products at each evidentiary tier and provides a conservative basis for integrating multi-omics with mechanistic and quantitative interpretation. Full article

Sustainable ridge-based peanut production following winter wheat requires soil preparation technologies capable of simultaneously ensuring precise ridge formation, reduced energy consumption and efficient in situ utilisation of crop residues. This study aimed to develop and experimentally validate a combined soil preparation technology integrating shallow tillage, deep loosening and ridge formation within a single field pass, and to quantify its technological and biological performance. Field experiments were conducted using a prototype combined machine with analytically justified geometric parameters of the working tools, followed by multifactor optimisation and statistical modelling. Technological performance was assessed by soil fragmentation degree and draft resistance, while biological effects were evaluated using residue incorporation (Pz), biodegradation coefficient after 60 days (k₆₀) and dehydrogenase activity after 30 days (DHA₃₀). The results showed statistically significant nonlinear relationships between tool parameters and technological responses, with coefficients of determination exceeding 0.94 for soil fragmentation and 0.97 for draft resistance. The proposed technology increased residue incorporation efficiency by 15–20%, enhanced biodegradation intensity (k₆₀) by up to 18%, and reduced energy consumption due to single-pass operation compared with conventional multi-pass systems. A strong relationship between Pz and biological indicators confirmed the key role of residue placement in controlling microbial processes. These findings demonstrate that integrated control of soil processing and residue placement enables energy-efficient single-pass technologies for ridge-based peanut production systems. Full article

The watershed boundaries in arid and semi-arid regions are critical zones where ecological vulnerability and socio-economic development are in severe conflict. The upper and middle reaches of the Yellow River basin are a typical example of this dilemma. Intensive land use and human developmental interventions in this region have severely disrupted the integrity and balance of the ecosystem. While spatially designated, networked conservation areas can effectively promote the integrity and balance of regional ecosystems, these areas may fail to capture dynamic changes in vulnerability. This study develops a “functional diagnosis-structural diagnosis-integrated optimization” framework. It integrates various scenarios to diagnose vulnerability under uncertainty and identifies bottlenecks in ecological networks. For functional diagnosis, the coupling of the sensitivity–resilience–pressure (SRP) model and the Ordered Weighted Averaging (OWA) algorithm accurately locates vulnerable areas within the regional ecosystem. In terms of structural diagnosis, the Morphological Spatial Pattern Analysis (MSPA), Minimum Cumulative Resistance model (MCR), and Circuit Theory are integrated to identify structural bottlenecks. The main findings of this study are as follows: (1) Functional Diagnosis: The coupling of SRP and OWA reveals the non-linear vulnerability responses to policy preferences and identifies areas that consistently exhibit functional vulnerability across different scenarios. (2) Structural Diagnosis: The circuit theory combined with MSPA and MCR analysis identifies 72 ecological pinch points. These bottlenecks represent the weakest structural nodes crucial for maintaining regional ecological robustness. (3) Coupled Delineation and Differentiated Restoration Strategies: High vulnerability areas identified by SRP and consistently vulnerable areas identified by OWA are combined to delineate four distinct ecological restoration units: Alpine Fragile Matrix Unit, Loess Hilly Soil Conservation Unit, Anthropogenic Pressure Pinch Point Unit, Key Structural Stepping Stone Unit. Differentiated ecological restoration strategies are proposed based on the varying sensitivity, resilience, and pressure characteristics of these units. The “functional-structural” coupled ecological vulnerability evaluation framework can precisely identify vulnerable areas. The delineated restoration units and their corresponding restoration strategies provide reference and supplementation for the protected areas system, offering transferable tools for enhancing regional ecological efficiency. Full article

The Qilian Mountains serve as a crucial ecological security barrier in western China, and the soil structural stability of alpine meadows directly affects regional ecological security and the sustainable utilization of grasslands. However, current research on grazing mostly relies on short-term artificially controlled experiments, which differ greatly from the pattern of long-term natural grazing. Herein, this study abandoned the artificially controlled grazing method and selected sampling areas with stable grazing regimes for more than a decade. Taking no grazing (CK) as the control, four treatments were established, including light grazing (LG), moderate grazing (MG), heavy grazing (HG) and extreme grazing (EG). The particle size distribution and stability of mechanically stable and water-stable soil aggregates in different soil layers were determined. Combined with environmental and biological factors, the effects of grazing on the structure and stability of soil aggregates were elucidated. The results showed that no grazing improved the mechanical stability of soil aggregates but reduced their water stability. Light and moderate grazing maintained a balanced and resistant soil structure, with the surface soil being more fragile than the subsurface soil. Heavy and extreme grazing led to severe structural degradation, with the subsurface soil being more fragile than the surface soil. Soil aggregate stability was jointly regulated by elevation, soil properties, root biomass, nitrogen forms, mineralization and microbial biomass. In conclusion, from the perspective of soil structural stability and sustainable utilization, light and moderate grazing represent the optimal utilization mode for the alpine meadows of the Qilian Mountains. This mode not only maintains the structural stability of subsurface soil aggregates but also balances biological cementation and physical disturbance, thus avoiding the insufficient water stability under no grazing and the risk of structural fragmentation under heavy or extreme grazing. Environmental and biological factors mediated the divergent responses of mechanical and water stability to different grazing intensities. The findings of this study provide a scientific basis and new insights for the rational grazing management and soil conservation of alpine meadows in the Qilian Mountains. Full article

Soil compaction and reduced infiltration capacity are critical constraints limiting soil physical quality and hydraulic functioning in semi-arid vineyard systems subjected to repeated machinery traffic. This study aimed to develop and evaluate a geometry-optimized strip tillage tool designed to improve structural functionality within the compacted root zone while minimizing inter-row disturbance. A U-shaped working body configuration, consisting of two oppositely inclined shanks and a central chisel, was theoretically substantiated and optimized using multifactor analysis. Field experiments were conducted to assess changes in penetration resistance, bulk density, and infiltration rate within the 20–40 cm soil layer under semi-arid conditions. The optimized geometry significantly reduced penetration resistance and bulk density in the trafficked strip, indicating alleviation of mechanical impedance and improved root-relevant physical conditions. Infiltration capacity increased after treatment, indicating enhanced hydraulic continuity within the root zone. Unlike full-width subsoiling, the localized strip intervention preserved inter-row soil stability and limited unnecessary disturbance, which is consistent with conservation-oriented soil management. The results indicate that geometry-optimized strip tillage is associated with improved soil physical quality and hydraulic function within compacted vineyard strips. The operational applicability of the developed implement may also depend on vineyard layout and terrain conditions. The prototype tool was tested under conditions representative of vineyards with standard row spacing and relatively moderate slopes typical for the experimental site. In vineyards with very narrow row spacing, steep slopes, or highly heterogeneous soil conditions, adjustments in working width, shank spacing, or tractor–implement configuration may be required. Future studies should therefore investigate the performance of the optimized geometry under contrasting vineyard configurations, including steep hillside vineyards and high-density planting systems. By linking implement design to quantitative soil structural and hydraulic indicators, this study contributes to the development of vineyard soil management practices for semi-arid perennial cropping systems. Full article

Hopea celebica Burck is an endangered dipterocarp endemic to Sulawesi, Indonesia, occurring in two ecologically contrasting habitats: karst and ultrabasic forests. These environments differ markedly in soil composition and topography, potentially driving ecological specialization and genetic divergence. To investigate the genetic variation and genetic structure of this species, we applied newly developed microsatellite (SSR) markers, together with the chloroplast DNA sequences of the trnL–trnF region. Genotypes at 15 SSR loci were determined for 255 individuals collected from six populations covering the range of the species’ distribution across karst and ultrabasic forests. Genetic diversity was consistently higher in karst than in ultrabasic populations. DIYABC and VarEff analyses revealed a historical bottleneck and earlier recovery in the karst populations. Analysis of molecular variance (AMOVA) revealed that 35% of the genetic variation was partitioned between habitat types (F_RT = 0.345, p = 0.001). Bayesian clustering (STRUCTURE), principal coordinate analysis (PCoA), and UPGMA dendrograms consistently showed two distinctive clusters corresponding to habitat type. Chloroplast haplotypes differed between populations in the karst and ultrabasic forests. These results suggest that populations in the karst and ultrabasic forests have undergone a long history of differentiation without migration. The strong habitat-related genetic structure likely reflects ecological isolation and early-stage speciation. We recommend treating the karst and ultrabasic populations as distinct conservation units to preserve the evolutionary potential and adaptive capacity of H. celebica under ongoing environmental change. Full article

Soil salinization poses a severe threat to global wheat production, yet the physiological mechanisms underlying photosynthetic responses to neutral, alkaline, and combined salt stress remain poorly understood. This study systematically evaluated the photosynthetic physiology and salt tolerance of six spring wheat genotypes under three types of salt stress at varying concentrations. By integrating phenotypic data, gas exchange parameters, chlorophyll fluorescence indices, and biomass measurements, and applying structural equation modeling and multivariate analysis, key traits regulating biomass were identified. The results revealed significant interactions among salt stress type, genotype, and concentration on photosynthetic parameters. Structural equation modeling analysis revealed that under neutral salt stress, both gas exchange parameters and chlorophyll content had significant direct effects on seedling biomass, with standardized path coefficients of 0.421 and 0.400, respectively. Under alkaline and combined salt stresses, only chlorophyll content showed a significant direct effect on biomass, with standardized path coefficients of 0.873 and 0.790, respectively. Multiple regression analysis further identified key photosynthetic factors influencing growth under different stress types. Under neutral salt stress, phi (Ro) and E significantly affected biomass, whereas under alkaline and combined salt stresses, biomass was primarily co-regulated by phi (Ro) and phi (Eo). Based on a comprehensive evaluation of salt tolerance index, damage index, and biomass response, genotypes W06 and W02 exhibited the strongest overall salt tolerance. This study systematically elucidates the differential response mechanisms of photosynthesis in spring wheat under distinct salt stress types, providing an important theoretical basis and elite germplasm resources for breeding salt-tolerant wheat varieties. Full article

Climate change and progressive aridification represent a substantial threat to the sustainability of wild medicinal plant resources in Central Asia. Rheum tataricum L.f. (R. tataricum), a mesoxerophytic species with high pharmacological potential and a restricted distribution range, was selected as a model for investigating adaptive responses to combined climatic and edaphic stress. Relationships among climatic parameters, soil agrochemical characteristics, anatomical and morphological traits, and the metabolomic profile of roots and rhizomes were analysed across six ecopopulations distributed along latitudinal and altitudinal gradients in southern and western Kazakhstan. To quantify population-level vulnerability to climatic stress, a Climate Sensitivity Index (CSI) was calculated. All investigated ecopopulations exhibited high climate sensitivity (CSI = 0.30–0.40), indicating persistent climatic stress. Significant altitudinal dependence was detected for such anatomical traits, as primary cortex thickness, as well as for the accumulation of tannins, anthraquinones, and flavonoids. The metabolomic profile was strongly associated with seasonal precipitation, temperature, relative air humidity, soil agrochemical properties, and root elemental composition. These findings demonstrate pronounced anatomical and metabolomic plasticity in R. tataricum, which appears to function as a key adaptive mechanism in arid ecosystems. The results provide a scientific basis for sustainable bioprospecting, conservation of natural populations, and targeted cultivation aimed at obtaining specific metabolomic profiles. Full article

Soil salinization has become a major global constraint threatening ecosystem stability and agricultural production. As a prominent salt-tolerant turfgrass, Paspalum vaginatum (seashore paspalum) serves as an excellent material for exploring salt tolerance mechanisms. In this study, PvHAK12, a high-affinity K⁺ transporter (HAK) family gene isolated from seashore paspalum, was functionally characterized. PvHAK12 encodes a 788 amino acid protein with 13 transmembrane domains, belonging to the plasma membrane-localized ion transporters. It exhibits high sequence conservation with other HAK transporters and is predominantly expressed in roots and stems, with distinct tissue- and time-specific induction under salt stress. Yeast complementation assays revealed that PvHAK12 has no obvious K⁺ transport capacity but may mediate Na⁺ transport. Overexpression of PvHAK12 in Arabidopsis thaliana significantly reduced salt tolerance at germination, seedling and rosette stages, as reflected by lower germination rate, fresh weight, survival rate, the maximum quantum yield of photosystem II (Fv/Fm) value and chlorophyll content, accompanied by higher ion leakage. Under salt stress, transgenic plants accumulated more Na⁺ and less K⁺, leading to an elevated Na⁺/K⁺ ratio. Moreover, transgenic lines displayed weaker antioxidant enzyme activities and higher reactive oxygen species (ROS) accumulation. Transcript analysis further demonstrated that PvHAK12 overexpression suppressed the induction of multiple ion-transport and stress-responsive genes under salt conditions. These results indicate that PvHAK12 negatively regulates plant salt tolerance by disrupting ion homeostasis, antioxidant capacity and stress-related gene expression. Full article

The alpine meadows on the Qinghai-Tibetan Plateau function as critical reservoirs for regional water resources, yet face severe degradation driven by climate warming and overgrazing. Although establishing Poa pratensis artificial grasslands is a common restoration strategy, their effectiveness in recovering hydrological functions along restoration chronosequence remains poorly quantified. This study evaluated the changes in water conservation capacity and its drivers across a degradation–restoration sequence in the Qilian Mountains comprising alpine meadow (AM), degraded meadow (DM), and 2-, 3-, and 13-year artificial grasslands (AG2, AG3, AG13). Vegetation characteristics, soil structural properties, and water-holding indices were measured to assess restoration outcomes. The results showed that compared to AM, water-holding capacity at 0–30 cm in DM declined by 75.3–85.8%, primarily due to fragmentation of the mattic epipedon and deterioration of soil aggregates. While artificial restoration improved vegetation traits and some soil properties, hydrological recovery exhibited a distinct lag. Specifically, soil water-holding capacity in artificial grasslands showed no statistically significant improvement compared to DM. Even in AG13, soil water storage remained significantly lower than that in AM. Mantel tests and regression analyses identified root mass density and mean weight diameter as the primary drivers governing water conservation capacity. These findings reveal that artificial grasslands cannot serve as functional hydrological reservoirs in a timely manner, highlighting the importance of conserving intact alpine ecosystems. Full article

Accurate soil moisture assessment is essential for effective agricultural management in the southern US, where water availability has a significant impact on crop productivity. This study evaluates the Soil Moisture Active Passive (SMAP) Level-4 daily soil moisture product using in situ measurements from Natural Resources Conservation Service (NRCS) Soil Climate Analysis Network (SCAN) stations and the US. Climate Reference Network (USCRN) across diverse agroecosystems in Texas from 2016 to 2024. SMAP’s performance was examined across ten climate zones and six major land cover types, including urban regions, pastureland, grassland, rangeland, shrubland, and deciduous forests. Statistical metrics, including the coefficient of determination (R²), Root Mean Square Error (RMSE), Bias, and unbiased RMSE (ubRMSE) were used to evaluate the agreement between SMAP-derived and in situ soil moisture measurements. Results show that SMAP effectively captures seasonal soil moisture dynamics but exhibits spatially variable accuracy. The highest agreement was observed at Panther Junction (R² = 0.57, RMSE = 2.29%), followed by Austin (R² = 0.57, RMSE = 9.95%). While a weaker coefficient of determination was observed at PVAMU (R² = 0.28, RMSE = 11.28%) and Kingsville (R² = 0.11, RMSE = 7.33%), likely due to heterogeneity in land cover, and urbanized landscapes in these stations. Applying the quantile mapping bias correction methods significantly reduced RMSE and improved the accuracy of SMAP soil moisture data at some in situ measurement stations. The results highlight the importance of station-specific calibration and the integration of satellite and ground-based measurements to improve soil moisture monitoring for agriculture and drought management in Texas and similar regions. Full article

In the process of anaerobic digestion for manure treatment, adding conductive materials is one of the most used methods to enhance methane yield. Biochar, a stable conductive material, shows significant potential in facilitating direct interspecies electron transfer in anaerobic digestion systems. However, biochar’s structure and properties are influenced by its preparation method, and the mechanisms by which structural characteristics affect methane yield and microbial community structure in fermentation systems require further investigation. This study investigates the effects of pyrolysis duration (1 h for A3O and 2 h for A3T) at 550 °C using corn straw as raw material. Through characterization analyses including SEM, FTIR, conductivity, and elemental composition, we explore the impacts on gas production efficiency and key parameters in anaerobic digestion systems. By analyzing microbial community structure and changes in methanogenic functional bacteria, we elucidate the mechanisms by which biochar materials with different pyrolysis times influence anaerobic digestion processes and microbial community composition. These findings provide theoretical foundations and support for optimizing biochar preparation techniques and their targeted applications in anaerobic digestion fields. It was found that the biochar-treated group exhibited higher methane production. Compared with the CK group without biochar, the methane production of A3O and A3T increased by 8.53% and 5.16%, respectively. While methane yield differed little between A3O and A3T, longer pyrolysis time increased the biochar’s specific surface area, promoting the system’s reaction rate and enabling faster methanogenesis. High-throughput analysis showed that biochar enriched methanogenic archaea like Methanosarcina and Methanobrevibacter while upregulating methanogenesis metabolic pathways and enhancing system metabolic potential. This study elucidates the influence of pyrolysis conditions on biochar performance and its regulatory role in anaerobic digestion, providing a basis for energy recovery from organic waste and biochar application in anaerobic fermentation. Full article

Coastal tidal flat soil organic carbon (SOC) is significantly affected by reclamation activities. However, the limited availability of historical SOC data constrains the reconstruction of past SOC. SOC data were integrated in current time-point and remote sensing data during the last two decades by applying machine learning (ML) methods such as random forest (RF), boosted regression trees (BRT), and extreme gradient boosting (XGBoost) to map the spatiotemporal distribution of tidal flat reclamation and the spatial distribution of SOC content in the western coastal region of the Bohai Rim over the last two decades and to explore how the period and type of reclamation affect SOC content. The results show that: (1) The area of tidal flats decreased by 61.92% from 2000 to 2020 due to reclamation activities. (2) Among the ML methods, the XGBoost model demonstrated the best performance (R² = 0.71, MAE = 0.93 g/kg, RMSE = 1.32 g/kg, d-Willmott = 0.98), with the modified normalized difference water index (MNDWI) being the most important predictor variable. (3) The SOC content of tidal flats decreased from 4.11 g/kg in 2000 to 3.33 g/kg in 2020, a reduction of 18.98%. (4) The reclamation of tidal flats into marshes, forest lands, grasslands, farmlands, and bare lands led to an increasing trend in SOC content, with the greatest increase observed in regions converted to farmlands. This study provides data support for the control of reclamation activities, creation of tidal flat conservation policies, and strategic decision-making for climate change mitigation. Full article

Soil nutrients and water are often distributed heterogeneously in space, yet how plant roots forage in response to such heterogeneity and how their strategies relate to functional traits remain poorly understood. Here, we conducted an indoor pot experiment manipulating water and nutrient supply in both homogeneous and heterogeneous patch patterns using seedlings of four tree species, focusing on root functional traits and foraging strategies. The results indicate that root foraging behavior exhibits both resource specificity and species specificity: roots tend to proliferate toward nutrient-rich and low-water patches as an adaptive strategy. Although no strict dichotomy was observed between high foraging scale (low precision) and low foraging scale (high precision) strategies under heterogeneous conditions, fine-rooted species (Acer truncatum and Koelreuteria paniculata) exhibited traits leaning toward “precise foraging”, whereas coarse-rooted species (Prunus davidiana and Quercus variabilis) tended toward a conservative “random walk” pattern, with no trade-off between root foraging scale and precision. Root morphological traits exerted significant nonlinear regulation on foraging scale: root biomass foraging scale (FS_RB) correlated positively with root diameter (RD) but negatively with specific root length (SRL) and specific root area (SRA); root length foraging scale (FS_RL) correlated positively with root length (RL), root tip number (RTN), SRL, and SRA. In contrast, root morphological traits could not explain the variation in foraging precision, suggesting that foraging precision constitutes another distinct dimension in root-trait space. In summary, this study provides key insights into the foraging strategies of plant roots in heterogeneous environments, expanding our understanding of the multidimensionality of root functional traits. Full article

Plant functional traits, as indicators of community responses to disturbances, are key drivers of ecosystem service multifunctionality (ESMF). However, the relative contribution of these traits to ESMF across different steppe types remains unclear. Using data from 101 sampling sites across Inner Mongolia’s meadow steppe (MS), typical steppe (TS), and desert steppe (DS), we examine the contributions and driving mechanisms of abiotic (climate and soil) and biotic factors (23 community-weighted mean functional traits and diversity indices) to ESMF across different steppe types. Our results show significant differences in ESMF across steppe types, with a decreasing trend from MS to TS to DS. Crucially, the driving factors of ESMF shift fundamentally across steppe types. In MS, ESMF is primarily driven by biotic factors (e.g., stem N:P ratio), whereas as aridity increases, abiotic factors (e.g., aridity and soil clay content) become more influential, ultimately dominating ESMF in DS. This shift from niche differentiation to environmental filtering as the dominant mechanism provides a crucial framework for predicting ecosystem service responses to global change. It highlights the importance of context-dependent grassland conservation strategies, advocating for location-specific management based on environmental gradients. Full article