Plateau Of China Research Articles

Evolutionary characteristics and influencing factors of agricultural regional system in the Loess Plateau of China under rapid urbanization

Evolutionary characteristics and influencing factors of agricultural regional system in the Loess Plateau of China under rapid urbanization

Rare and Abundant phoD‐Harboring Bacteria Mediate the Mineralization of Organic Phosphorus Fractions in Soil Aggregates During Cut Slope Restoration

ABSTRACTPhosphorus (P) is the key nutritional element in the soil of cut road slopes undergoing ecological restoration, and the transformation of organic P (Po) is a crucial part of the P cycle. However, the role of phoD‐harboring bacteria in driving the mineralization of Po fractions in road slope soil aggregates is unclear. This study analyzed road slope soils that had undergone 7, 11, and 14 years of restoration in the western Sichuan Plateau of China. We examined the differences and associations between the Po fraction content, alkaline phosphatase (ALP) activity, and community composition of rare and abundant phoD‐harboring bacteria in soil aggregates of four particle sizes (0.053–0.25, 0.25–2, 0.053–0.25, and, > 2 mm). The results showed that NaHCO3‐extracted Po (NaHCO3‐Po) content in soil aggregates increased with restoration years, while NaOH‐extracted Po (NaOH‐Po) content decreased. ALP activity in soil aggregates increased with restoration years, but there was no significant relationship between ALP activity with the phoD‐harboring bacterial community. There were significant differences in the composition of rare and abundant phoD‐harboring bacterial communities during slope restoration. Soil moisture, pH, organic carbon, and the C:P ratio in soil aggregates were the primary factors affecting the distribution of the Po fractions and the phoD‐harboring bacterial community. NaHCO3‐Po and NaOH‐Po in soil aggregates were likely the main substrates for ALP‐mediated Po mineralization. More genera were involved in Po mineralization in slope soils restored for 14 years than in soils restored for 7 and 11 years, and rare phoD‐harboring genera were more actively involved in Po mineralization than abundant phoD‐harboring genera. This study provides some theoretical basis for P effectiveness enhancement and P management during slope soil restoration.

Two species of Polycelis (Platyhelminthes, Tricladida, Planariidae) newly recorded for the Qinling Mountains and the Loess Plateau in China, with a comparative discussion on their karyotypes

The paper details new geographic records of two species of the genus Polycelis Ehrenberg,1831 (Platyhelminthes, Tricladida, Planariidae) for the Qinling Mountains and the Loess Plateau in China and provides redescriptions of these species based on an integrative taxonomic study involving morphology, karyology, and histology. This new information considerably expands our knowledge on these species, for which until now only limited data was available. The species Polycelis asiatica Selinova, 1985 is characterized by the following features: 63–80 eyes; sperm ducts that exhibit an intrabulbar knee-shaped bend towards the ventral surface before opening separately and symmetrically into the antero-dorsal portion of a large seminal vesicle; the latter is ventrally displaced, thus creating a narrow ventral lip on the penis papilla; dorsal wall of the seminal vesicle is provided with several well-developed folds; more or less bulbous penis papilla protrudes from the dorsal wall of the male atrium and is provided with a slender and flexible tip; chromosome complement diploid with 30 metacentric chromosomes, 8 submetacentric chromosomes, and 2 subtelocentric chromosomes. The species Polycelis eudendrocoeloides (Zabusova, 1929) is characterized by: 49–80 eyes; highly reduced and blunt penis, provided with a kind of flagellum that projects into the seminal vesicle; a relatively thick coat of circular and longitudinal muscles around the entire male atrium; generally, a very large intrabulbar seminal vesicle, extending from near the ventral body surface to occupy the major part of both the penis bulb and the dorso-ventral space of the body; diploid chromosome complement consisting of 36 metacentric chromosomes.

The Spatiotemporal Dynamics of Vegetation Cover and Its Response to the Grain for Green Project in the Loess Plateau of China

The Spatiotemporal Dynamics of Vegetation Cover and Its Response to the Grain for Green Project in the Loess Plateau of China

Long-term alfalfa planting mediates the coupling of soil water and organic carbon storage in a semi-arid area of the Loess Plateau, China

The key to restoring arid and semi-arid ecosystems is maintaining soil water and organic carbon contents. Alfalfa (Medicago sativa L.) is a high-yield perennial forage crop and performs ecological functions as a drought-resistance leguminous herb. It has been widely planted for reconstruction of degraded soils in the Loess Plateau in northwestern China, but long-term planting may affect soil carbon–water coupling and lead to crop yield reduction. To maximize the benefits of reconstructed grassland, this study explored the couplings of soil water, organic carbon, and alfalfa productivity along a reconstruction chronosequence in a semi-arid area of the Loess Plateau. Space-for-time substitution approach was used to select different-aged stands of reconstructed grassland (1, 5, 7, 10, 15, 20, 30 years old). Alfalfa above-ground biomass (AGB), soil water storage (SWS), organic carbon storage (SOCS), and carbon–water coupling coordination degree (D) were measured in the 0–100 cm soil profile. Alfalfa AGB reached a peak in the 7th year, and the degradation began in the 10th year. Both SWS and SOCS varied nonlinearly with stand age. The greatest loss of SWS occurred in the 15th year (80–100 cm depth), whereas the largest increase of SOCS occurred in the 30th year (0–20 cm depth). There was a negative feedback relationship between AGB and SWS over the 30-year study period (Pearson r = −0.835, P = 0.098). AGB and SOCS initially showed a trade-off within the first 10 years (Pearson r = −0.7431, P = 0.2569), in contrast to their positive feedback in the 20–30th years (Pearson r = 0.9978, P = 0.0421). A decoupling between SWS and SOCS (D < 0.6) was observed after 12 years of alfalfa planting. For agricultural production, a greater supply of water and organic fertilizer is required from the 7th year of alfalfa planting, and reseeding may be needed around the 10th year to prolong the life of alfalfa community. Alfalfa should be planted for no more than 12 consecutive years in the study area for ecological protection.

Optimizing plastic film mulch to improve the yield and water use efficiency of dryland maize in the Loess Plateau, China.

Knowledge on the variation of yield and water use efficiency under different mulching methods is important for guiding rained maize production in the Loess Plateau area. In this study, eight different plastic film mulching methods was established to analyze the maize growth, soil water content and soil temperature changes of dryland maize, and increase yield and water use efficiency (WUE). The field experiment was conducted in 2019, and eight treatments were set up, including a traditional flat planting without mulching (CK), ridge-furrow with ridges mulching black plastic film and furrows mulching straw (HJ), ridge-furrow with ridges mulching black plastic film and furrows bare (HL), ridge-furrow with ridges mulching liquid plastic film and furrows mulching straw (YJ), ridge-furrow with ridges mulching liquid plastic film and furrows bare (YL), ridge-furrow with ridges mulching biodegradable plastic film and furrows mulching straw (SJ), ridge-furrow with ridges mulching biodegradable plastic film and furrows bare (SL) and ridge-furrow with ridges bare and furrows mulching straw (NJ). Furthermore, the AHP-TOPSIS was employed to evaluate the optimal mulching method for maize. The results showed that compared with CK and NJ treatment, the soil water content and soil storage were significantly changes with other treatments in the reproductive period of maize. Among the six mulching methods, maize yield in HJ, HL, YJ, YL, SJ, and SL treatments were 46.28%, 61.95%, 70.30%, 51.02%, 52.02% and 53.53% significantly greater than CK treatment. In addition, dryland maize WUE was 66.53% and 84.01% higher in the YJ and YL treatments with ridges mulching liquid plastic film than in the CK treatment, respectively. The optimal treatments of economic benefits were YL and HJ. Through AHP-TOPSIS comprehensive analysis, the optimal mulching methods were YL and HJ treatment. Current field trials indicate that YL treatment could serve as a promising option to improve dryland maize yield, WUE, and reducing environmental risks in the Loess Plateau of China.

Genomic Characterization and Comparative Analysis of Streptococcus zhangguiae sp. nov. Isolated from the Respiratory Tract of Marmota Himalayana.

Two Gram-stain-positive, oxidase-negative, non-motile, facultative anaerobic, α-hemolytic, coccus-shaped bacteria (zg-86T and zg-70) were isolated from the respiratory tracts of marmots (Marmota Himalayana) on the Qinghai-Tibet Plateau of China. Phylogenetic analysis of the 16S rRNA gene and 545 core genes revealed that these two strains belong to the Streptococcus genus. These strains were most closely related to Streptococcus respiraculi HTS25T, Streptococcus cuniculi CCUG 65085T, and Streptococcus marmotae HTS5T. The average nucleotide identity (ANI) and digital DNA‒DNA hybridization (dDDH) were below the threshold for species delineation. The predominant cellular fatty acids (CFAs) in this novel species were C16:0, C18:0, and C18:1ω9c, whereas the primary polar lipids were phosphatidylglycerol (PG), phosphatidylethanolamine (PE) and an unknown phosphoglycolipid (PGL). The optimal growth conditions for the strains were 37°C, pH 7.0, and 0.5% (w/v) NaCl on brain-heart infusion (BHI) agar supplemented with 5% defibrinated sheep blood. Comparative genomics analyses revealed the potential pathogenicity of strain zg-86T through comparisons with suis subclade strains in terms of virulence factors, pathogen-host interactions (PHIs) and mobile genetic factors (MGEs). Based on the phenotypic characteristics and phylogenetic analyses, we propose that these two isolates represent novel species in the genus Streptococcus, for which the names Streptococcus zhangguiae sp. nov. (the type strain zg-86T=GDMCC 1.1758T=JCM 34273T) is proposed.

Biochar application improves maize yield on the Loess Plateau of China by changing soil pore structure and enhancing root growth

Biochar application emerges as a valuable soil management strategy for enhancing crop yield; however, the mechanisms underlying the relationships between soil and plants remain unclear after biochar application. In this study, soil pore characteristics and maize yield were assessed in a five-year biochar-application experiment on the Loess Plateau of China, including four treatments: Control (no biochar), low-dose biochar application (LB, 3 t ha−1), moderate-dose biochar application (MB, 6 t ha−1), and high-dose biochar application (HB, 9 t ha−1). Root growth traits were evaluated by cultivating maize in intact soil cores collected from field conditions using X-ray computed tomography. Our findings indicate that, compared to the Control, the HB treatment enhanced macroporosity (> 0.1 mm in diameter), porosity of 0.1–0.5 mm pores, and saturated water content, while reducing macropore connectivity and penetration resistance. However, biochar application treatments did not alter the water retention characteristics from field capacity to permanent wilting point or the plant-available water content (PAWC). Furthermore, the mean angle of primary and seminal roots as well as the length and surface area of entire roots increased in the HB treatment, showing a positive correlation with the porosity of 0.1–0.5 mm pores. The mean diameter of primary and seminal roots, leaf fresh and dry weights, and maize yield also increased in the HB treatment compared to the Control. Partial least squares path modeling analysis indicated that biochar application rates positively impacted on root growth and plant productivity through an indirect influence of soil pore size distribution, with 0.1–0.5 mm pores being particularly crucial for facilitating deeper root penetration and root elongation. These findings demonstrate that biochar application primarily augmented 0.1–0.5 mm pores, rather than affecting smaller pores capable of retaining plant-available water or larger macropores, enhancing deeper rooting and root elongation, thus improving plant productivity and crop yield.

Diagnostic value of CT in patients with stable chronic obstructive pulmonary disease at high altitude: Observational study.

This research aims to explore the diagnostic value of computed tomography (CT) indicators in patients with stable chronic obstructive pulmonary disease (COPD) in a plateau of China, and to find out the correlation between CT indexes and lung function and symptoms. This study screened out 53 stable COPD patients and 53 healthy people through inclusion and exclusion criteria in Hongyuan county, Aba Prefecture, Sichuan Province, between July 2020 and December 2020, and then collected their baseline data, conducted lung function tests and chest CT scans, and collected COPD Assessment Test (CAT), modified Medical Research Council Dyspnea Scale (mMRC) scores. The CT indexes of the 2 groups were compared, binary logistic regression was used to analyze the influence of COPD, the receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of the CT indexes for COPD. The Spearman test was used to understand the correlation analysis between the CT indexes and lung function, symptom score, and the number of acute exacerbations. Multiple linear regression was used to analyze the influencing factors of lung function. The percentage of low-attenuation areas less than -950 Hounsfield units (%LAA-950; t = -4.387,P = 0), percentage of wall area (WA%; t = -4.501, P = 0), and thickness-diameter ratio (TDR; t = -4.779, P = 0) in the COPD group were higher than those in the normal group. ROC shows that: %LAA-950 (P = .047) and TDR (P = .034) were independent influence in COPD in the plateau. %LAA-950 combined with TDR (AUC = 0.757, P < .001) had the value of diagnosis of COPD in the plateau. All 3 indexes are negatively correlated with lung function, and positively correlated with the symptoms and the number of acute exacerbations. Multiple linear regression analysis showed that the main factors for decrease of ratio of measurement to prediction of forced expiratory volume to the first second (FEV1%) included %LAA-950 (OR = -0.449, P < .001) and WA% (OR = -0.516, P < .001). CT indexes have a certain diagnostic value in patients with stable COPD at high altitude.

Cosesimic surface deformation and source mechanism of the 2023 Ms 6.2 Jishishan earthquake, northeastern Tibetan Plateau

On 18 December, 2023, the Ms 6.2 Jishishan earthquake struck the border region of Gansu province and Qinghai province in the northeastern Tibetan Plateau in China. Field investigations revealed that the 2023 Ms 6.2 Jishishan earthquake produced a ∼1.2-km-long coseismic surface deformation zone with the characteristic centimeter-sized uplift and bulge in the range of 1–13cm (generally<5 cm), which was mainly restricted to a narrow corridor of 40–50 m in width along an previously-unknown frontal blind fault of the North Lajishan thrust fault zone. In spatial location, the coseismic surface deformation zone corresponds to the core of a late Cenozoic anticline on the hanging wall of blind fault, indicating that the coseismic surface uplift was constrained by the pre-existing tectonic environment.The North Lajishan thrust fault zone is composed of the west branch fault (F1), east branch fault (F2) and the frontal blind fault (F3), the surveying results document that only the frontal thrust fault (F3) is the Holocene seismically active fault. Thus, the seismogenic fault of the 2023 Ms 6.2 Jishishan earthquake was suggested to be the F3 fault, indicating the northeastward propagation and expansion of the most recent earthquake activities within the North Lajishan thrust fault zone related to the ongoing northeastward shortening of the northeastern Tibetan Plateau accommodating the Eurasia-India continental collision.

Towards the mechanical stability of biocrusts in drylands: Insights from inorganic ions and organic compounds and their interactions

Biocrusts are an important component of dryland ecosystems as they perform crucial ecological functions like stabilizing soils, mediating the hydrological cycle, and improving nutrient availability. The high mechanical stability of biocrusts is understood to be linked to exopolymeric substances (EPS), which in turn, are responsible for the adsorption of various ions and chemical compounds. This study aimed to investigate the chemical composition of biocrusts and assess potential correlations between their chemical composition and mechanical stability. Samples of three types of biocrusts (cyanobacteria, cyanobacteria and moss mixed, and moss crusts) and bare soil (as control) were collected from the northern Loess Plateau of China. The inorganic ions and organic compounds present in biocrusts were quantified using inductively coupled plasma-optic emission spectrometry, ion chromatography, and gas chromatography-mass spectrometry. Biocrust mechanical stability was assessed by penetration resistance (PR) and the mean weight diameter (MWD) of aggregates. Finally, the contribution of inorganic ions and organic compounds to the stability of the biocrusts was elucidated. The results indicated that all three types of biocrusts were more stable than bare soil, with moss crusts being the most stable. Chemical analyses revealed an enrichment of inorganic ions such as K+, Ca2+, Na+, Mg2+, SO42–, and halogen ions within the biocrusts, while they showed a depletion of Fe2+, Al3+, and NO3–. Ten types of organic compounds were identified in biocrusts and bare soil, with medium-chain alkanes and long-chain acids being the dominant compounds. In some cases, acids accounted for more than 40 % of the total organic compound content of the biocrusts. Redundancy analysis showed that the content of inorganic ions, such as Ca2+ and Mg2+, and organic compounds such as acids, amides, and alkenes, exhibited the closest association with the biocrust stability. Partial least squares path modeling indicated that both inorganic ions and organic compounds indirectly affected biocrust stability by influencing electric conductivity, bulk density, EPS, and fine particle (clay and silt) content. A strong association was found between the inorganic ions and PR or MWD (0.658 and 0.744, respectively), whilst the total effect of organic compounds on PR and MWD was 0.814 and 0.801, respectively. It is suggested that both the magnitude and types of chemicals associated with EPS indicate their capability to grant mechanical stability of the biocrusts, which in turn is conducive to maintaining the critical functions of biocrusts in global drylands.

Influence of micromorphology and water content on the rheological properties and performance evaluation model of loess mudflow

Evaluation of the rheological characteristics of loess mudflow is of great significance to ecological environment protection (by loess, we mean a wind-blown Quaternary silt deposit), and geological disaster assessment in the Loess Plateau of China. Rheological characteristics of rheology for loess mudflow are highly variable due to heterogeneity in particle micromorphology and water content, and current rheological models struggle to reconcile the structural dynamics with the equilibrium behavior of soil at different concentrations and microstructures. A rheological study of loess mudflow for five regions on the Loess Plateau was carried out in this investigation, and the results showed that loess transformed from a solid-like stage to a liquid-like stage under steady loads and exhibited significant shear thinning characteristics and shear rate dependence, in which the shear rate less than 2 s−1 was the main region of loess strength attenuation and the maximum yield stress is about 1411 Pa. A smaller water content and more complex particle micromorphology led to a higher yield stress, but there was no significant correlation between flow index and particle shape and water content. Additional structural dynamics and particle fractal theory were then introduced, providing an improved model that could reconcile the structural dynamics and particle micromorphology of loess with its equilibrium behavior at different water contents and shear stresses. All the test data were distributed around a dimensionless master curve. Considering the difficulty of obtaining rheological parameters, an evaluation criterion containing three levels (clay-rich, silt-rich, and sand-rich) for the evaluation of the rheological properties of loess mudflow was proposed, which can reconcile the test results and models under different working conditions. Such an evaluation criterion can also be applied to soils of other textures, providing a straightforward manner to determine the relevant rheological parameters. The research results provide a theoretical basis for ecological environmental protection and geological disaster assessment in the Loess Plateau region based on rheological characteristics.

Determining of gully erosion susceptibility based on UAV and machine learning in Loess Plateau

In order to determine the susceptibility of gully erosion at a small watershed scale on the Loess Plateau of China, three hybrid models were developed. These models were based on the Multi-Attributive Border Approximation Area Comparison (MABAC), frequency ratio (FR), CatBoost (CB), LightGBM (LG), and extremely-randomized tree (ET). Based on the Unmanned Aerial Vehicles (UAV) photos, a total of 83 gullies with 12,150 gully pixels and 8 conditioning variables were extracted and used to create the gully inventory database. The correlations between the conditioning parameters and the pixels of gullies were then determined using FR, and the relative importance of these conditioning factors was quantified using machine learning. Then, for gully erosion susceptibility mapping (GESM), three hybrid gully erosion susceptibility models called MABAC-FR-CB, MABAC-FR-LG, and MABAC-FR-ET were developed. The performance of three hybrid models was assessed using the receiver operating characteristic curve (ROC) and the Kappa coefficient. The results claimed that slope steepness greatly influenced the erosion of the gully. The MABAC-FR-ET performed the most precisely, with area under curvature (AUC) of 0.998 and a Kappa of 0.952. As a result, it was determined that MABAC-FR-ET is the most exact and accurate method for predicting the susceptibility to gully erosion in the study watershed.

Spatial downscaling of SMAP soil moisture to high resolution using machine learning over China’s Loess Plateau

Soil moisture (SM) is a critical physical parameter in land surface processes that affects the atmospheric and hydrological cycles. Soil Moisture Active Passive (SMAP) mission produces high-quality global SM data, but its low spatial resolution limits the applications at a regional or local scale. In this study, we developed a novel method to select optimal factors from 34 candidate downscaling factors for each month using three machine learning methods (Back Propagation Neural Network (BPNN), Support Vector Machine (SVM) and Random Forest (RF)) to produce monthly time series SM products at a spatial resolution of 1 km for the entire Loess Plateau in China from 2015 to 2023. 11 in-situ SM measurements distributed in Loess Plateau and precipitation data were used to evaluate the downscaling performances of the three machine learning approaches. The results show that the spatial trends of the three downscaled SM were essentially the same as the SMAP SM, with similar spatial patterns, and all three downscaled SM can provide more spatial information and texture features than SMAP SM. Among the three types of downscaled SM, the RF downscaled SM reached the highest R (0.654) and the smallest unbiased Root Mean Square Error (ubRMSE) (0.044 m3m−3), better than the BPNN and SVM downscaled SM, and most closely matched the in-situ measurements. The dynamics of SM were successfully captured by RF downscaled SM, which exhibited strong temporal consistency with the in-situ SM and responded well to precipitation events, with significant increases in SM values in the month of high precipitation and subsequent months. In conclusion, the RF model has the best downscaling effect and it can be used to provide high spatial resolution SM data for applications at a regional or local scale across the Loess Plateau.

Optical turbulence in the atmospheric surface layer at the Pamir Plateau Muztagh-ata site

Abstract In this paper, we conducted a detailed analysis of optical turbulence in the Atmospheric Surface Layer (ASL) at Muztagh-ata site during on-site testing. We utilized ultrasonic anemometers positioned on a 30-meter tower to collect and process data at five height levels, obtaining data from October 1, 2021 to the present. We investigated the behavior of optical turbulence parameters ($C_n^2$ and seeing ϵ) in the ASL. Nighttime $C_n^2$ primarily fluctuated in the range of 10−16 to 10−14, exhibiting an exponential decrease with height. During the day, it showed a h−0.82 dependency, while at night, it displayed a h−0.48 dependency. Additionally, we presented the distribution of seeing across different layers within the ASL, showing a gradual decrease with increasing height, with a median seeing of 0.24 arcseconds at nighttime and 0.48 arcseconds at daytime between 6-30m. We investigated the relationship between surface temperature inversion, seeing in the ASL, and wind speed at the site. Our results show that under temperature inversion conditions, seeing significantly improves and is often accompanied by low to moderate wind speeds, while high wind speeds are usually associated with poorer seeing. Preliminary calculations and observational results, combined with the high altitude and unique geographical location, suggest that Muztagh-ata site has the potential to be an outstanding optical astronomical observatory in the western plateau of china.

Multi-scale analysis of nutrient and environmental dynamics in Hongfeng Lake Southwest China

Traditional linear correlation analysis may not fully capture the true relationship between these variables. Therefore, multi-scale running correlation analysis, such as time-dependent intrinsic correlation (TDIC) and continuous wavelet transform based on Hilbert–Huang transform (HHT), provides valuable insights into local correlations and the evolving relationship between nutrients and environmental factors over time. In this study, we investigated seven environmental factors and four water quality nutrient indicators in deep lakes on the Yungui Plateau in southwestern China. The results revealed that there may be strong correlations between environmental factors and nutrient levels during certain periods, while opposite trends may emerge at other times. These variations in correlation could be attributed to uncertain physical processes, spatial heterogeneity, or the impact of different climatic factors on local hydrological processes. Wavelet analysis indicated that changes in environmental factors lag behind those in nutrient levels, particularly on a cycle of about 12 months. This suggests that changes in environmental factors align with natural patterns after the water body has been polluted. These conclusions underscore the complexity and dynamic nature of the relationship between environmental factors and nutrient levels in water bodies, highlighting the importance of employing advanced analysis techniques to capture this complexity.

Spatiotemporal desynchronization in the propagation from meteorological to soil moisture drought in the Loess Plateau, China

Study RegionThe Loess Plateau (LP) of China Study FocusMeteorological drought (MD) would propagate to soil moisture drought (SMD) with spatiotemporal desynchronization. The spatial desynchronization between them has frequently been ignored in previous studies due to limitation of identified droughts, which did not consider their 3-dimensional (3D, i.e. longitude, latitude and time) properties. This study presents a 3D perspective on the spatiotemporal desynchronization in the propagation from meteorological to soil moisture drought in the the Loess Plateau (LP) of China, using an improved drought matching method. Event Synchronization (ES) is extended to determine temporal linkage of the two types of droughts and spatial connection is tested using overlapping area. New Hydrological Insights for the RegionThe results showed that: (1) the improved method is reasonable for identifying MDs that trigger SMDs, down to specific clusters; (2) 8 SMDs preceded MDs 1 month, while approximately 79 % of SMDs did not recover after the determination of MDs; (3) severity of MD is an impact factor on recovery lag, while antecedent soil moisture dominates onset lag with the relative importance of approximately 50 %; and (4) incompletely overlap in migration trajectory between the two types of droughts was mainly caused by temperature, followed by antecedent soil moisture and potential evapotranspiration, with relative importance of 55 %, 14 % and 12 %, respectively.

A spatial syntactic analysis of temple cultural heritage settlements on the western Sichuan plateau of China

The protection and development of the cultural heritage of temple settlements, the utilization of cultural resources, and the inheritance of settlement characteristics are pressing issues that require urgent attention. To address these challenges, this study employs the spatial syntax research method to delve into the spatial form of the cultural heritage of temple settlements on the western Sichuan plateau. Specifically, the study focuses on four distinct settlement types in Ganzi Tibetan Autonomous Prefecture, China: Baiyu Temple, Ganzi Temple, Dongga Temple, and Gesang Temple. Using Depthmap software, the study quantifies settlement parameter values and analyzes connection value, integration degree, and comprehensibility, to reveal their syntactic structural characteristics. Our findings indicate that these four temple settlements present an organic whole in terms of spatial form. However, there are distinct differences in their syntactic structures, which are closely linked to factors such as settlement scale, historical inheritance, and other contextual influences. Based on our spatial syntax analysis, the study proposes a series of protective measures and development strategies. First, emphasis should be placed on preserving the overall spatial layout and organic integrity of temple settlements to prevent overdevelopment and the disruption of original patterns. Second, planners must strengthen the protection and management of internal spatial elements to maintain their interrelationships. Finally, planners should formulate differentiated protection and development plans tailored to the unique characteristics and values of each temple settlement type. While the study focuses on traditional settlement spatial forms and their relationship with human behavior, further exploration is needed to investigate the impact of political, economic, and environmental factors on these forms.

Structures and properties of the late pleistocene paleosols of the loess-soil section of Obi-Mazar (Tajikistan)

The loess-soil series of Central Asia cover the history of subaerial sedimentation of the last 2–2.5 mln years. Significant thicknesses, a large number of paleosols, and an impressive chronology place the loess-soil series of the Afghan-Tajik depression on a par with the famous sections of the Loess Plateau of China. The study of the most significant sections located within the Khovaling Loess Plateau makes it possible to develop a regional chronostratigraphic chart, to study the structure and conditions of formation of the main stratigraphic benchmarks–buried paleosols. The present study is devoted to the clarification of the structural features of loess and paleosols of the Late Pleistocene in one of the sections of the Khovaling–Obi-Mazar Plateau. Based on the results of stratigraphic dissection, description of the macro- and micromorphological structure, magnetic susceptibility analysis, study of the chemical and granulometric composition, a comprehensive description of the structure and properties was carried out and the most probable conditions for the formation of paleosols and loess were established. In the Late Pleistocene part of the section, two loess layers and a pedocomplex PC1 with three welded paleosols, consisting of a total of 7 horizons, are distinguished. The deposits are characterized by high silt content, carbon content, and the presence of signs of pedogenesis and biological activity in all layers of the studied section. Available data indicate the presence of a poorly developed MIS 3 paleosol in the upper loess layer. The developed pedocomplex PC1 of Obi-Mazar, according to its stratigraphic position, structural features, and magnetic susceptibility data, belongs to the MIS 5. According to preliminary data, its formation occurred in semi-humid and humid conditions under forest vegetation, which contributed to the biogenic segregation of Fe-Mn compounds, as well as intra- and interhorizon redistribution of carbonates due to diagenetic processes. Towards the end of the Last Interglacial, gradual aridization occurred, due to which the upper paleosol to be the least developed.

Effects of Different Land Uses and Slope on Runoff and Soil Loss on the Loess Plateau of China

ABSTRACTThe Loess Plateau has one of the most serious areas of soil erosion in China; therefore, studying the effect of soil and water conservation measures on the erosion of loess soil slopes is important for land management and agricultural development. This study is based on 5 years of field runoff observations and rainfall data from 2015 to 2019. Correlation and regression analyses were used to study the runoff and sediment production of loess soil and its relationship with rainfall, slope and land use. The results show that &gt; 80% of the erosive rainfall occurs mainly in July to August in the area. Runoff and soil loss from the plots differed substantially, depending on land use, soil conservation measures and slope degree. Bare plots experienced the highest soil loss rate of over 27 t/ha with higher runoff depth, followed by cultivated plots (4.55 t/ha), grass plots (0.43 t/ha), shrub plots (0.35 t/ha) and forest plots (0.13 t/ha). Among the four soil and water conservation measures, the runoff and sediment reduction benefits of forest and shrub plots were the highest. The runoff reduction benefit fluctuated at approximately 0.8, and the benefit of sediment reduction was ≈1. The overall performance was forest &gt; shrubland &gt; grassland &gt; cultivated land &gt; bare land, and the benefits of sediment reduction were greater than those of runoff reduction. Forests had the highest soil retention capacity on slopes from 5° to 25°, and forests on gentle slopes had the best water storage capacity. Shrub plots had the best water storage capacity when they were on steep slopes. Rainfall erosion forces were significantly and positively correlated (p &lt; 0.01) with runoff depth and soil loss, making it the most significant rainfall indicator of sediment production. Under the same rainfall conditions, soil and water conservation measures are still required on bare slopes, land use is the main control factor for slope sediment production, and appropriate land use can greatly reduce the threat of slopes in terms of soil erosion. This study shows that soil and water conservation measures are imperative to prevent runoff and soil loss, especially for bare land without any measures; on steep slopes, a vegetation combination primarily featuring shrubs is expected to achieve greater benefits in reducing runoff and sediment. This study can provide a scientific basis for the management of vegetation measures and the implementation of soil and water conservation measures on loess soil slopes.