Search Results (978)

Curcuma lampangensis Saensouk, Maknoi & Rakarcha is a member of the family Zingiberaceae within the genus Curcuma L. This species is endemic to Thailand and is classified as critically endangered due to its restricted distribution and the ongoing degradation of its natural habitats. The species predominantly occurs in areas that are increasingly impacted by anthropogenic activities, particularly agricultural expansion, which contributes to habitat fragmentation and poses a significant risk to its persistence in the wild. In addition, propagation by rhizomes or seeds shows relatively low propagation efficiency. Therefore, plant tissue culture techniques are considered important for improving propagation efficiency. In this study, shoot and root induction of C. lampangensis were investigated by culturing on solid and liquid MS medium for 8 weeks, supplemented with different plant growth regulators including BA, kinetin, IAA, IBA, NAA, 2,4-D, TDZ, mT and Ads. The results showed that solid MS medium supplemented with 2 and 3 mg/L mT induced the highest mean number of shoots of 7.26 to 7.63 shoots per explant, a mean roots number of 18.57 to 19.88 roots per explant, and 30 to 60% callus formation. Meanwhile, liquid MS medium without plant growth regulators induced the highest mean number of roots of 34.73 roots per explant, with a mean root length of 3.49 cm. Acclimatized rooted plantlets transferred to sandy soil showed 85% survival rate. Full article

Ecologically fragile areas typically overlap with impoverished zones, rendering them susceptible to a vicious cycle of ecological degradation and poverty aggravation. Reasonable and diversified ecological compensation methods are closely associated with improved livelihood resilience among rural households in sandy areas. Building on this, we take three leagues and cities in Inner Mongolia with severe sandy desertification as the study area. OLS regression and mediating effect models are employed to examine the impact of diversified ecological compensation methods on the livelihood resilience of rural households in sandy areas, as well as the underlying mechanisms and heterogeneity. The results demonstrate that (1) diversified ecological compensation methods exert a significant positive effect on the livelihood resilience of rural households in sandy areas; (2) perceived fairness and livelihood diversity mediate the association between diversified ecological compensation methods and the livelihood resilience of rural households in sandy areas; (3) the effects of diversified ecological compensation methods on the livelihood resilience of rural households in sandy areas vary significantly across compensation modalities, beneficiary groups, and regions. Specifically, capacity-building compensation exerts a significantly stronger effect than direct-transfer compensation; poverty-alleviated households benefit more than general households; and the effects are significantly stronger in western Inner Mongolia than in eastern Inner Mongolia. Therefore, in optimizing ecological compensation policies in sandy areas, it is suggested to enhance the embedding depth of industrial and technical compensation, and to explore differentiated compensation pathways based on regional market capacity and household group characteristics, thereby promoting sustainable livelihood development for rural households in sandy areas. Full article

Soil wind erosion (SWE) remains a significant challenge to improving ecological environmental quality and achieving sustainable socioeconomic development in drylands of northern China. An in-depth understanding of the spatio-temporal variations and underlying mechanisms of regional SWE is a prerequisite for the scientific prevention and mitigation of erosion-related hazards. However, in regions with high variability in intra-annual climate, quantitative studies on the spatial heterogeneity and intra-annual variability of drivers of SWE are scarce. This knowledge gap poses challenges for policymakers in developing effective landscape management strategies that are spatially and temporally specific. Here, the dynamics of SWE in the Xilingol typical steppe of China were simulated using the Revised Wind Erosion Equation (RWEQ) at seasonal and annual scales during 2000–2020. Stepwise regression and geographically weighted regression (GWR) were employed to examine the spatial heterogeneity in the relationships between SWE and environmental variables. The results revealed that RWEQ simulations were significantly correlated with the frequency of dust storm events at the seasonal scale (R² = 0.807, p < 0.01). SWE in spring accounted for approximately two-thirds of the annual total, indicating that spring was the critical period for SWE control. High SWE intensity was concentrated in sandy soil regions, with the Otindag Sandy Land and Gahai Elesu Sandy Land being identified as priority areas for desertification prevention and control. Over the study period, SWE exhibited an overall decreasing trend at both seasonal and annual scales, suggesting an enhancement in the ecosystem’s capacity for windbreak and sand stabilization. The stepwise regression results indicated that climatic factors generally had greater explanatory power than topographic and landscape pattern variables. Wind speed showed the strongest association with SWE across different time scales, whereas the relationships of normalized difference vegetation index (NDVI) and precipitation with SWE exhibited clear seasonal dependence. The GWR results further revealed pronounced spatial heterogeneity and seasonal variability in both the direction and magnitude of the associations between SWE and climatic and landscape pattern variables. These findings provide scientific support for identifying priority areas for desertification prevention and for developing spatio-temporally targeted landscape management strategies in dryland sandy regions. Full article

This study investigated retinal interspecific differences between two sympatric lizards from the Turpan Basin of Xinjiang that occupy distinct microhabitats. Eremias roborowskii inhabits shrublands, while Phrynocephalus axillaris lives in open sandy areas. We adopted retinal whole-mounting, paraffin sectioning, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to compare retinal structure, oil droplet traits, photoreceptor arrangement, and ultrastructural characteristics between the two species. Both species exhibited five types of colored oil droplets, a temporal fovea, and a highly vascularized conus papillaris, confirming cone-dominant retinas. P. axillaris had larger oil droplets with an average diameter of 3.719 ± 1.100 μm. In contrast, E. roborowskii showed a higher oil droplet density of 1473 ± 1203 ind/mm². The inner plexiform layer (IPL) was significantly thicker in E. roborowskii (56.01 ± 14.76 μm) relative to P. axillaris (50.76 ± 15.25 μm). The two species also differed markedly in photoreceptor ultrastructure. E. roborowskii contained mitochondria-rich ellipsoids, while P. axillaris possessed glycogen-enriched paraboloids. These structural variations reflect compatibility with local ambient light conditions. E. roborowskii is predisposed to suit diffuse shrubland light through high droplet density and mitochondrial-dominant ellipsoids, whereas P. axillaris tends to accommodate intense open-field sunlight via larger oil droplets and well-developed paraboloids. This study provides key morphological evidence to reveal how microhabitat divergence drives retinal specialization among desert reptiles. Full article

Transitions within the syn-rift stage provide a key window for examining sediment-routing changes and associated sedimentary responses in lacustrine rift basins. In the Bohai Bay Basin, the interval from the third member (Es3) to the second member (Es2) of the Eocene Shahejie Formation records a transition from early strong rifting toward relatively stable rifting. The Qinan Sag, a secondary sag along the Qikou Sag margin, was sensitive to this transition. Using cores, well logs, three-dimensional (3D) seismic data, and heavy-mineral data, this study reconstructs the source configuration, palaeogeomorphology, depositional-system evolution, and Es3–Es2 source-related sediment-dispersal domains. The results show that the supply pattern shifted from coeval supply by a southern regional source and northern and western local sources during Es3 to southern regional-source dominance during Es2. Accordingly, Es3 contains strongly differentiated braided-delta, fan-delta, and subaqueous-fan assemblages. Es2 contains weakly differentiated shallow-water delta and beach-bar assemblages. Three source-related sediment-dispersal domains coexisted during Es3. During Es2, the northern domain was no longer identified, and the western gentle-slope belt evolved into a high-sand-ratio beach-bar belt. This reorganization was mainly controlled by the combined effects of source-configuration changes, geomorphic segmentation, and contrasting slope–A/S conditions (A/S = accommodation/sediment supply). Supply-pattern simplification and weakened geomorphic segmentation shifted sediment routing after basin entry from multiple, dispersed pathways to dominant-source-controlled focused routing. Moderate-to-steep slopes and higher relative A/S proxy values during Es3 favoured discrete, segmented sandy-deposit preservation; gentle slopes and lower relative A/S proxy values during Es2 promoted focused routing and preservation of sandy deposits along the dominant direction, with local shallow-water enrichment. Across the Es3–Es2 syn-rift stage transition, regional-source-related sediment routing showed stronger persistence; local-source-related routing more often weakened or terminated, with corresponding areas tending to show shallow-water redistribution and enrichment signals. Full article

Biological soil crusts (BSCs) play key roles in arid, semi-arid regions and ecological marginal habitats. This study focused on four types of sand-fixing plantations established in 1990 in alpine sandy land (Salix psammophila, SL; Caragana korshinskii, NT; Salix cheilophila, WL; Populus simonii, XYY). Soil samples were collected from bare sand, algae crusts, and moss crusts. Soil particle size distribution, physicochemical properties, and enzyme activity were determined. Then bacterial communities were analyzed using high-throughput (Illumina) sequencing and the correlations among these three factors were examined. The results showed that: (1) From bare sand to algae and moss crusts, the content of fine particles (clay + silt) gradually increased. (2) Soil water content (SWC), nutrients and enzyme activities increased progressively. (3) In the study area, the dominant bacterial phyla of BSCs included Pseudomonadota, Cyanobacteria, Actinobacteriota and Vibrionota. Principal Coordinates Analysis (PCoA) and Analysis of Similarities (ANOSIM) results showed that BSCs drive the differentiation of bacterial communities during succession, while forest stands influence their spatial distribution. (4) Spearman’s correlation and redundancy analysis (RDA) showed that available phosphorus (AP), alkaline hydrolyzable nitrogen (AN), soil organic matter (SOM), catalase (CAT), pH, soil water content (SWC), and alkaline phosphatase (ALP) are key physicochemical factors shaping the bacterial community structure of BSCs. Mantel’s test confirmed that these variables mediated BSCs’ bacterial community structure. This study elucidates the mechanisms underlying ecological restoration via BSCs and provides a theoretical basis for future restoration efforts in alpine sandy land. Full article

Sea level rise poses a major threat to dry beach areas, particularly in low-lying and managed coastal environments. Reliable assessments of future beach vulnerability therefore require the combined consideration of sea level rise, tidal regime, meteorological forcing, and wave-driven processes. Here, a physically based methodology is applied to evaluate future inundation and beach response at five representative sandy beaches along the southern coast of Spain. The selected sites span mesotidal Atlantic and microtidal Mediterranean settings. The approach integrates present-day conditions with sea level rise projections under RCP 4.5 and RCP 8.5 scenarios, astronomical tide, and meteorological residuals. Wave run-up is estimated using the IH2VOF CFD (Computational Fluid Dynamics) model. Extreme still water levels and maximum inundation levels are derived for mid-century (2026–2045) and end-of-century (2081–2100) periods, and their impacts on available dry beach surface and beach width are quantified using cross-shore profiles. Results indicate a progressive reduction in dry beach surface and width across all sites, with impacts intensifying from mid- to end-century and from moderate to high-emission scenarios. While losses remain comparatively moderate under still-water assumptions, the inclusion of wave effects leads to substantially larger impacts. At the most vulnerable sites, dry beach surface losses reach up to 80% under still-water conditions, and up to complete loss (100%) when wave run-up is included, particularly along the mesotidal Atlantic coast. Overall, the results demonstrate that neglecting wave run-up can lead to a substantial underrepresentation of future beach inundation, and that its explicit inclusion provides a more reliable basis for beach management and adaptation planning under sea level rise. Full article

Northeast China’s black soil region serves as a critical cornerstone of national food security, yet accelerating soil degradation, characterized by declining soil organic matter (SOM) and rising bulk density (BD), threatens the productive capacity of its farmland. Understanding how soil physicochemical properties regulate crop yields in this ecologically heterogeneous landscape is essential for sustainable agricultural development. Here, 2916 soil samples from 201 counties across six ecological zones were analyzed in conjunction with county-level rice and maize yield records. Our findings revealed that crop yield determinants are fundamentally governed by regional resource endowment characteristics rather than uniform factors. In areas characterized by sandy soil texture, low precipitation (<400 mm yr⁻¹), and inherently low fertility, elevated bulk density (BD, >1.34 g cm⁻³) and alkaline soil conditions (pH > 7.0) constitute the primary constraints to productivity through restricting root development. Conversely, in regions with fertile mollisols and high baseline soil organic matter (SOM > 40 g kg⁻¹), nutrient dynamics emerge as the dominant yield-regulating factors. For volcanic soil landscapes with strong phosphorus fixation capacity, available phosphorus deficiency represents the critical bottleneck for maize production. Path analysis further demonstrates that BD and pH operate predominantly through indirect mechanisms, modulating SOM accumulation and nutrient cycling rather than directly constraining yield. Threshold analysis identified that BD exceeding 1.34 g cm⁻³ and SOM below 26 g kg⁻¹ markedly reduce productivity, while SOM levels above 40 g kg⁻¹ yield diminishing marginal returns. These findings advance our mechanistic understanding and provide scientific foundations for spatially differentiated soil conservation and precision nutrient management strategies essential for sustaining grain production capacity in northeast China’s black soil region. Full article

Understanding the variation law and prediction method of thermal conductivity for NaCl-bearing aeolian sand is of great significance for the thermal parameter selection and temperature field analysis of engineering structures including subgrades, foundations and lined water conveyance canals in the saline soil region of southern Xinjiang. The thermal conductivity of NaCl-bearing aeolian sand under different dry densities, moisture contents and salt contents was measured via the transient plane source (TPS) method. The variation law and corresponding influence mechanism were analyzed, and a thermal conductivity prediction model was established. The experimental results indicate that the thermal conductivity of NaCl-bearing aeolian sand increases with increasing dry density and moisture content, showing strong linear correlations with both parameters. At a salt content of 2%, the maximum increase in thermal conductivity induced by increasing moisture content reached 29.3%, which was approximately 1.53 times the increase observed at a salt content of 8% (19.17%). In contrast, the influence of salt content on thermal conductivity exhibited a nonlinear trend. With increasing salt content, the thermal conductivity initially decreased and then increased, and the salt content corresponding to the minimum thermal conductivity shifted toward higher values with increasing moisture content. Specifically, this critical salt content gradually shifted from 2% to 6%. This law reveals that the increase in dry density and moisture content improves the thermal conductivity of the soil mainly by enhancing the solid and liquid heat transfer pathways, whereas the variation of salt content is controlled by the water–salt coupling effect. The model calculation results show that the established prediction model is in good agreement with the measured experimental data (R² = 0.9674), with favorable applicability and high prediction accuracy. It can provide a reliable reference for the thermal calculation of sandy foundations and related engineering materials in saline soil areas. Full article

The rapid advance of urbanization and social development has intensified the complexity of engineering projects, especially where geotechnical constraints play a decisive role. Expanding cities increasingly occupy areas with challenging soil conditions, such as collapsible soils, which demand careful investigation and innovative design solutions. These geotechnical factors directly influence the safety, durability, and cost-effectiveness of infrastructure, making integrated analysis essential from the earliest stages of project planning. An experimental study with lateritic sandy soil was performed to investigate the effect of rice husk ash (RHA) on collapsible soil behavior. Collapsible soils occur worldwide in diverse geological and geotechnical conditions and can result in costly structural damage. Due to intense leaching during tropical weathering, lateritic soil structures and textures show high collapse potential, with substantial volume reduction under constant stress when wetted. The investigated soil was collected in a tropical area of the Paraná Basin (Brazil) and is considered representative of large regions with similar geological conditions. Soil samples and mixtures (2, 4, 6, 8, 10, 12, and 14 wt.% RHA) were tested using standard geotechnical procedures such as grain size distribution and compaction tests. Collapsibility behavior (i.e., collapse potential, CP) was measured using oedometer tests. Tests were conducted with realistic compaction degrees (~80%), representing conditions found in nature and in civil works involving collapsible soils. The results show that RHA can considerably reduce the collapse potential of lateritic fine sandy soils, mainly due to its packing effect, which reduces volumetric changes with increased moisture. The CP was significantly reduced from 9.83% to 1.93% in the mixture containing 14% RHA. Full article

In this study, we investigate the bearing capacity characteristics and controlling mechanisms of coastal beach sand in Quanzhou Bay, Fujian Province, China. The results provide support for coastal engineering construction and vehicle trafficability assessment in beach areas, while field sampling, laboratory static plate load tests, and data-based modeling were conducted to examine the effects of moisture content, particle size distribution, and relative density on the bearing behavior of beach sand. In total, 52 groups of static load tests were performed, with the results showing that relative density is the dominant controllable factor affecting the bearing capacity of coastal beach sand. When the relative density increased from 40% to 65%, the ultimate load increased by 80%, and the deformation modulus increased by 139.9%. The optimal relative density range was approximately 52–65%, and the improved particle size distribution enhanced bearing performance. The ultimate load of well-graded sand was 60% higher than that of poorly graded sand, and moisture content showed a threshold effect, with the best mechanical performance occurring at a moisture content of about 7%, whereas excessive moisture content significantly reduced the bearing capacity. Under natural conditions, the proportional limit load of medium-dense coastal beach sand in Quanzhou Bay was approximately 200 kPa, the ultimate load was 250 kPa, and the characteristic value of bearing capacity was 125 kPa, while the dominant failure mode was general shear failure. A semi-empirical bearing capacity model was also developed; its average relative error was 10.35%, indicating that it has both physical meaning and engineering applicability. The findings provide a reference for foundation design evaluation in Quanzhou Bay and similar coastal beach areas. Full article

Tunnel construction in soft soil environments involves significant geological and hydraulic uncertainty, particularly where permeable sandy interlayers within soft clay are prone to seepage-induced instability and excessive settlement. Although hydraulic–mechanical coupling is widely recognized, the spatial variability of key soil parameters (e.g., permeability and elastic modulus) is often inadequately represented, limiting quantitative evaluation of heterogeneous ground effects on construction-induced deformation. In this study, statistical analyses of site investigation and monitoring data are conducted to characterize parameter distributions and transverse settlement trough morphology, supporting model validation. A fluid–solid hydro-mechanical coupled numerical model in ABAQUS demonstrates that groundwater flow increases maximum surface settlement from 3.18 cm to 3.58 cm, confirming the significance of hydraulic coupling. To quantify spatial variability effects, a stochastic finite element framework based on random field theory is developed, showing that variations in vertical correlation length influence both the mean and dispersion of maximum settlement. Specifically, under a settlement control threshold of 40 mm, the failure probability decreases from 24.21% to 1.01% as the vertical correlation length increases from 1.5 m to 6 m. Finally, an engineering-oriented risk assessment framework is established using settlement trough area as the core loss indicator; its lognormal distribution is verified, and failure probability and reliability indices are integrated with code-based thresholds to evaluate construction risk under different scenarios, with the resulting risk levels ranging from Relatively High (Level III) to Moderate (Level II). Full article

To explore the regulatory mechanisms of different vegetation types on soil crust grain-size characteristics in sandy lands, this study focused on five typical plant species (Haloxylon ammodendron, Artemisia ordosica, Nitraria tangutorum, Agriophyllum squarrosum, and Phragmites australis) in an artificial vegetation restoration area on the northeastern edge of the Ulan Buh Desert. Using laser granulometry and graphical methods, we systematically determined the soil particle size composition and parameters of the crust (Layer A) and sub-crust (Layer B) layers, and analyzed their correlations with plant morphological parameters (crown width, plant height, basal diameter). The results showed that (1) different vegetation types significantly increased the content of soil fine particulate matter (silt and clay), with fine sand accounting for 42.85% and silt accounting for 23.64%; (2) there are significant differences in the impact of different vegetation types on particle size parameters. The average particle size of soil crust under Phragmites australis is the smallest (1.91), and the sorting is the worst (standard deviation 2.01). Under the vegetation type of Nitraria tangutorum, the average particle size of the soil crust layer is the largest (5.25), and the fractal dimension is the highest (2.46). (3) The crown width, plant height, and basal diameter of vegetation are negatively correlated with mean particle size, kurtosis, and fractal dimension (r= −0.62 to −0.45), and positively correlated with standard deviation and skewness (r = 0.51 to 0.68). (4) The frequency curve indicates that vegetation types broaden the distribution range of soil particles, and Phragmites australis and Artemisia ordosica exhibit bimodal characteristics. This study reveals the impact of vegetation restoration on soil grain size parameters in arid regions. These findings provide actionable strategies for optimizing vegetation configuration in actual desert restoration projects, notably proposing a “herbs first, shrubs follow” approach that can be directly applied to enhance restoration efficiency. Full article

In the Ordos Basin, one of the most important oil- and gas-bearing basins, the Triassic Yanchang Formation has formed important source rocks, but is also a typical representative of continental deep-water sedimentation. In the Huacheng area of the Upper Triassic Yanchang Formation, the deep-water gravity flow sedimentation characteristics of the lake-bottom fan are complex, and the spatial distribution pattern and stacking style of the sand bodies are of great significance for oil and gas resource exploration. Based on core observation, by combining well logging and analysis of signs of sedimentary facies, including petrologic features and primary sedimentary structures, the thick massive sand bodies of the Chang 6 Member belong to deep-water gravity flow deposits, and they develop in a semi-deep to deep lacustrine environment in the Huachi area, Ordos Basin. The primary sedimentary structures of deep-water gravity flows include massive bedding, graded bedding, sliding fractures, slumping deformation structures, turbidite sequences, and synsedimentary offsets. Two kinds of deep-water gravity flows of the channel system, namely sandy debris flows and turbidity currents, were identified in the sublacustrine fan. The sublacustrine provided accommodation space for the rapid unloading and accumulation of gravity flows. Deposited sandy debris flows are the most widely distributed in the sublacustrine fan. Three types of stacked sand bodies developed in the Chang 6 Member of the Huachi area, including multi-stacked thick-layered, sandstone–mudstone interbedded, and sand-thin and mud-thick types. The multi-stacked thick-layered sand bodies consist of multi-period massive sandstones, which are interpreted as sandy debris flow deposits. Sandstone–mudstone interbedded types exhibit diverse lithologies, including massive sandstone and deformed structural sandstone. In addition, the turbidity current is the primary factor controlling the stacked sand bodies. Sand-thin and mud-thick sand bodies consist primarily of laminated mudstone, massive mudstone, and flaser-bedded sandstone, and these deposits were formed by waning-stage turbidity currents and the rigid heads of sandy debris flows. Full article

Sandstone of the Lower Cretaceous Luohe Formation is the main water inrush source in the Binchang Mining Area in the southwestern Ordos Basin. Its sedimentary environment and provenance features are critical for local coal development and safe mining. The Luohe Formation at Xiaozhuang Coal Mine comprises three vertical members: the lower member dominated by coarse- to medium-grained sandstones, the middle member mainly composed of fine-grained sandstones, and the upper member characterized by interbedded fine- to medium-grained sandstones and sandy conglomerates. This subdivision newly identifies a complete hydrodynamic evolutionary cycle of depositional environments from high-energy to low-energy and back to high-energy conditions. Integrated petrographic observations and analyses of major and rare earth elements first confirm that the tectonic affinity of the Luohe Formation progressively shifted from a passive continental margin to an active continental margin, accompanied by a corresponding transition in sediment provenance from the North China Craton to a magmatic arc source region. Trace element compositions precisely indicate that the Luohe Formation was deposited in a fluvial freshwater environment under hot, arid, and oxidizing conditions, thus providing new constraints on the paleoenvironmental evolution of the region. Full article