Southwest Region Of China Research Articles

A Novel Dataset Replenishment Strategy Integrating Time-Series InSAR for Refined Landslide Susceptibility Mapping in Karst Regions

The accuracy of landslide susceptibility mapping is influenced by the quality of sample data, factor systems, and assessment methods. This study aims to enhance the representativeness and overall quality of the sample dataset through an effective sample expansion strategy, achieving greater precision and reliability in the landslide susceptibility model. An integrated interpretative framework for landslide susceptibility assessment is developed using the XGBoost-SHAP-PDP algorithm to deeply investigate the key contributing factors of landslides in karst areas. Firstly, 17 conditioning factors (e.g., surface deformation rate, land surface temperature, slope, lithology, and NDVI) were introduced based on field surveys, satellite imagery, and literature reviews, to construct a landslide susceptibility conditioning factor system in line with karst geomorphology characteristics. Secondly, a sample expansion strategy combining the frequency ratio (FR) with SBAS-InSAR interpretation results was proposed to optimize the landslide susceptibility assessment dataset. The XGBoost algorithm was then utilized to build the assessment model. Finally, the SHAP and PDP algorithms were applied to interpret the model, examining the primary contributing factors and their influence on landslides in karst areas from both global and single-factor perspectives. Results showed a significant improvement in model accuracy after sample expansion, with AUC values of 0.9579 and 0.9790 for the training and testing sets, respectively. The top three important factors were distance from mining sites, lithology, and NDVI, while land surface temperature, soil erosion modulus, and surface deformation rate also significantly contributed to landslide susceptibility. In summary, this paper provides an in-depth discussion of the effectiveness of LSM in predicting landslide occurrence in complex terrain environments. The reliability and accuracy of the landslide susceptibility assessment model were significantly improved by optimizing the sample dataset within the karst landscape region. In addition, the research results not only provide an essential reference for landslide prevention and control in the karst region of Southwest China and regional central engineering construction planning but also provide a scientific basis for the prevention and control of geologic hazards globally, showing a wide range of application prospects and practical significance.

Erosive Rainfall Thresholds Identification Using Statistical Approaches in a Karst Yellow Soil Mountain Erosion-Prone Region in Southwest China

Karst yellow soil is one of the most important cultivated soils in southwest China. At present, only a few studies have dealt with rainfall erosivity and erosive rainfall thresholds in the karst yellow soil region. This paper utilizes statistical methods to identify erosive rainfall thresholds and slope erosion-prone areas in the Qianzhong region. This analysis is based on long-term experimental data from 10 experimental stations and 69 experimental plots within the region in 2006 to 2022. The findings show the following: The rainfall amount threshold was 12.66 mm for woodland plots, 10.57 mm for grassland plots, 9.94 mm for farmland plots, and 8.93 mm for fallow plots. Soil and water conservation measures in forestry and grassland effectively increase the rainfall amount thresholds. Compared to farmland, the rainfall threshold increased by 27.32% for woodland and 6.32% for grassland. Bare land and farmland are erosion-prone areas in the karst yellow soil region. The erosive rainfall thresholds for farmland plots with slopes of 13°, 15°, 20°, 23°, and 25° were 10.41 mm, 10.28 mm, 9.66 mm, 9.52 mm, and 9.15 mm, respectively. With the increase in the 13–25° slope gradient of farmland, the initial rainfall required for runoff generation leads to a reduction. The wrong selection indices (WSI) of all landcover plots were less than 10%, and the efficiency indices (EFF) were between 80.43% and 90.25%. The relative error index (REI) of the erosive rainfall thresholds for all landcover runoff plots was less than 0.50%, very close to 0, indicating that these thresholds have small errors and high accuracy. This study gained a better understanding of natural rainfall-induced erosion characteristics in the study area, determined rainfall thresholds for distinguishing erosive rainfall events from non-erosive across different landcover types, and reduced the workload of calculating rainfall erosivity while enhancing the accuracy of soil erosion forecasting and simulation in the karst mountain yellow soil area.

Daily trunk radial growth patterns in relation to precipitation in orange trees in the dry-hot valley region of Southwest China

The dry-hot valley regions of Southwest China suffer droughts and high temperatures coexist environment. The efficient use of rainfall makes it possible for plants to safely cope with the environmental stress in the region. To reveal the driving mechanism of rainfall on typical tree secondary growth, orange tree (Citrus sinensis L. Osbeck), the commonly grown economic tree in the region was selected. Trunk diameter, sap flow, leaf humidity, meteorological conditions and soil water content were simultaneously monitored for the 2020–2022 period. Based on frequency distribution of trunk diameter changes data, trunk diameter changes were classified into positive growth (dramatic expansion, and common expansion), and negative growth (dramatic shrinkage, and common shrinkage) types. Furthermore, the relationships among the different growth patterns and rainfall or drought events were analyzed. The results showed: i) Trunk diameter maintained positive growth on rainy days, whereas both positive and negative growth occurred on rainless days. Although rainy period was not frequent, a high proportion of the total growth occurred during that time. ii) The common expansion type with a high frequency contributed to approximately 30% of the total growth, whereas the dramatic expansion type with a low frequency contributed to approximately 70% of the total growth. iii) There was a highly significant correlation between dramatic tree diameter expansion and rainfall. iv) Cumulative growth in tree diameter during rainy period was significantly driven by the duration of rainfall, the wetting time of leaf and the amount of rainfall. v) Compared with rainfall amount, the time rainfall related indexes were more closely related with tree dramatic diameter expansion. vi) While increasing soil water content and dry air mitigation due to rainfall enhanced average growth, it concurrently suppressed negative growth of tree trunk diameter after rainfall. The study confirmed that rainfall was critical for tree diameter growth in dry-hot valley regions of Southwest China. Relevant results are beneficial for improving understanding of plant precipitation utilization mechanism and could provide useful information on extreme meteorological hazards assessment in the context of climate change.

Impacts of wastewater treatment plant effluents on dissolved inorganic carbon in highly urbanized karst rivers, Southwest China

Wastewater treatment plants (WWTPs) are an important manifestation of the impact of urbanization on aquatic ecosystems, and the influences of effluents discharge from WWTPs on receiving river carbon biogeochemical cycle processes has been a research hotspot. However, our knowledge about potential impacts of WWTP effluents on dissolved inorganic carbon (DIC) cycle in karst rivers is rather limited. This study investigates the water chemistry and carbon isotope composition (δ13CDIC) in the urbanized reach of a river that drains the world’s largest continuous karst region in Southwest China, in an attempt to determine the effects of WWTP effluents on karst river DIC cycle and source discrimination. The results reveal: (1) Partial pressure of dissolved carbon dioxide (pCO2) levels in the river increased noticeably during the dry and normal seasons after receiving WWTP effluents; (2) There existed an ionic ratio overlap between end-members of silicate rock weathering and WWTP effluents which requires caution in identifying end-members of rock weathering in urbanized karst rivers; (3) DIC in the highly urbanized karst rivers was affected by complex geochemical processes and these processes varied in different seasons; (4) The contribution of WWTP effluents to the riverine DIC pool was 21±13 %, 58±21 % and 66±33 % in the wet, dry, and normal seasons, respectively. These findings highlight the interference of WWTP effluents with DIC carbon cycling in the receiving karst rivers. Since DIC from WWTPs do not relate with consuming atmospheric or soil CO2, it is important to exclude their contribution from the watershed’s rock weathering carbon sink budget. Based on these findings, we insist that the role and effect of WWTP effluents should be carefully considered when examining DIC carbon source and cycling in rivers that drain urbanized watersheds with abundant wastewater treatment plants.

Effects of fertilization on soil ecological stoichiometry and fruit quality in Karst pitaya orchard

Pitaya (Hylocereus undulatus) is a significant cash crop in the karst region of Southwest China. Ecological stoichiometry is an essential method to research biogeochemical cycles and limiting elements. The purpose of this study was to explore the stoichiometric characteristics of C, N, and P in Karst pitaya orchards and fruit quality and to elucidate the mechanism and process of nutrient cycling. The results showed that: (1) Fruit quality was highest under the combination of chemical and organic fertilizers. Compared to the control, the contents of per-fruit weight, vitamin C, and soluble sugar increased significantly by 55.5%, 60.7%, and 23.0%, respectively, while the content of titratable acidity decreased significantly by 22.0%. (2) The content of soil nutrients under fertilization stress showed a downward trend in general, as did microbial biomass and extracellular enzyme activities. (3) Different fertilization treatments significantly affected the soil-microbial stoichiometry C:N ratio, C:P ratio, with research areas being significantly limited by C and P. (4) Spearman and PLS-SEM (partial least squares-structural equation model) analysis results showed that under the influence of fertilization, there was a significant positive effect between microorganisms and soil nutrients, but a significant negative effect between soil nutrients and quality. The results of this study offer an innovative perspective on pitaya quality research in Karst areas.

Neonicotinoids as emerging contaminants in China's environment: a review of current data.

Neonicotinoids (NEOs), the most widely used class of insecticides, are pervasive in the environment, eliciting concerns due to their hydrophilicity, persistence, and potential ecological risks. As the leading pesticide consumer, China shows significant regional disparities in NEO contamination. This review explores NEO distribution, sources, and toxic risks across China. The primary NEO pollutants identified in environmental samples include imidacloprid, thiamethoxam, and acetamiprid. In the north, corn cultivation represents the principal source of NEOs during wet seasons, while rice dominates in the south year-round. The high concentration levels of NEOs have been detected in the aquatic environment in the southern regions (130.25ng/L), the urban river Sects.(157.66ng/L), and the downstream sections of the Yangtze River (58.9ng/L), indicating that climate conditions and urban pollution emissions are important drivers of water pollution. Neonicotinoids were detected at higher levels in agricultural soils compared to other soil types, with southern agricultural areas showing higher concentrations (average 27.21ng/g) than northern regions (average 12.77ng/g). Atmospheric NEO levels were lower, with the highest concentration at 1560pg/m3. The levels of total neonicotinoid pesticides in aquatic environments across China predominantly exceed the chronic toxicity ecological threshold of 35ng/L, particularly in the regions of Beijing and the Qilu Lake Basin, where they likely exceed the acute toxicity ecological threshold of 200ng/L. In the future, efforts should focus on neonicotinoid distribution in agriculturally developed regions of Southwest China, while also emphasizing their usage in urban greening and household settings.

Prevalence and genotype distribution of human papillomavirus infection among 66000 women from 2014 to 2023 in the plateau region of Southwest China

BackgroundPersistent infection with high-risk human papillomavirus (HR-HPV) plays a key role in the onset of cervical cancer. This study was designed to examine the epidemiological trends and genotype distribution of HPV from 2014 to 2023 in the plateau region of Southwest China.MethodsThe findings could offer valuable insights for clinical screening of cervical cancer and the formulation of HPV vaccination policies. This retrospective study analyzed 66,000 women who received HPV-DNA testing at the First People’s Hospital of Qujing, Yunnan, China, between 2014 and 2023. The cohort consisted of 33,512 outpatients, 3,816 inpatients, and 28,672 individuals undergoing health examinations. Cervical cells were collected for DNA extraction, and PCR amplification along with Luminex xMAP technology were used to detect 27 HPV genotypes. The data analysis was conducted using GraphPad Prism and IBM SPSS Statistics 27 software.ResultsThe overall HPV infection rate at the First People’s Hospital of Qujing declined from 24.92% in 2014 to 16.29% in 2023, averaging 16.02%. Specific infection rates were 18.50% among outpatients, 12.97% among inpatients, and 13.53% for health examination attendees. The predominant high-risk HPV genotypes identified were HPV52 (2.61%), HPV16 (2.06%), HPV58 (1.81%), HPV53 (1.55%), and HPV39 (1.09%). Meanwhile, the most frequent low-risk HPV genotypes were HPV6 (1.30%), HPV61 (1.21%), and HPV11 (0.85%). In HPV-positive cases, the distribution of single, double, triple, and quadruple or more infections were 79.90%, 15.17%, 3.59%, and 1.33%, respectively. The proportions of pure LR-HPV, pure HR-HPV, and mixed infections were 22.16%, 67.82%, and 10.02%, respectively. Age-specific analysis revealed a bimodal distribution of HPV infection, with the infection rate rapidly decreasing from 44.02% in the ≤ 19 age group to 19.55% in the 20–29 age group and 13.84% in the 30–39 age group, followed by a gradual increase to 14.64% in the 40–49 age group, 16.65% in the 50–59 age group, and 22.98% in the ≥ 60 age group. The coverage rates of the three available vaccines are all below 50%. The results of this study indicated a declining trend in HPV prevalence in the plateau region of Southwest China over the period from 2014 to 2023, especially in the reduction of genotypes targeted by vaccines.ConclusionThere were significant variations in the genotypes prevalent among different age groups, years, and patient sources within the same region. The underwhelming vaccination rates emphasize the critical need for developing either a multivalent vaccine or a personalized vaccine that targets the HPV genotypes common in the Chinese population. Furthermore, vaccinating adolescents to curb HPV infection and ensuring regular cervical cancer screenings for postmenopausal women are crucial steps.

Conversion of farmland to forest or grassland improves soil carbon, nitrogen, and ecosystem multi-functionality in a subtropical karst region of southwest China

The conversion of farmland to forest in China has been recognized for its positive impact on above-ground vegetation and carbon sequestration. However, the impact on soil quality during land conversion, particularly in vulnerable karst areas, has received less attention. In this study conducted in a karst area of southwest China, eight different farmland conversion strategies were investigated to assess improvements in surface soil carbon, nitrogen, and ecosystem multi-functionality (EMF). Our results showed that farmland converted to afforestation areas or farmland that was abandoned contained higher amounts of carbon (total, organic, active) and ammonium nitrogen (NH4+-N) in the soil compared to farmland converted to grassland or maize crop. Soluble organic carbon levels were higher in afforestation and grassland areas compared to maize crop controls. By contrast, soil from grassland and abandoned land exhibited higher levels of nitrate nitrogen (NO3--N) compared to afforestation land or maize crop controls. There were no differences in NH4+-N content between any condition, except for afforestation land that specifically contained the Zenia insignis plant species. Afforestation land consistently exhibited higher EMF values than grassland. Pearson correlation analysis revealed positive relationships between soil indices and EMF scores, except for NO3--N.Random forest analysis explained 95% of the variation in soil EMF and identified specific soil factors: total carbon, organic carbon, active labile organic carbon, total nitrogen, and ammonium nitrogen, as the main drivers of soil multi-functionality. Our studies show how various reforestation strategies can enhance soil nutrient sequestration and improve soil multi-functionality of farmland in the karst areas.These findings provide insight into sustainable soil management practices for converting farmland into natural areas.

Morphology and ITS sequences provide insights into the phylogeny of Tongoloa (Apiaceae) from China

BackgroundTongoloa is a genus comprising approximately 20 species, primarily distributed in the mountainous regions of southwest China. The insufficiency of specimen materials and morphological similarities among species render it a taxonomically challenging genus within the Apiaceae family. To elucidate the phylogenetic relationships and taxonomy of Chinese Tongoloa, this study utilized a total of 115 nrITS sequences, including 47 recently obtained sequences, for phylogenetic reconstruction.ResultsPhylogenetic relationships reconstructed from ITS sequences indicate that the East Asia Clade and the Komarovia Clade are sister groups, and Tongoloa belongs to the East Asia Clade. Species of Tongoloa are subdivided into 3 distinct groups, all sharing similar fruit morphologies and are clearly differentiated from related taxa. Several Tongoloa-like members classified under other genera are interpreted to be closely related to Tongoloa. Morphological and molecular data indicate that Tongoloa, Sinolimprichtia subclade and Chinese Trachydium subclade are separate yet genetically contiguous taxa. It is confirmed that Tongoloa zhongdianensis belongs to the Hymenidium Clade, while Sinocarum is classified within the Acronema Clade. Two new taxa are found in the Hengduan Mountains.ConclusionTongoloa is a genus within the East Asia Clade of Apiaceae, and the phylogeny reconstructed based on ITS sequences divides it into 3 main groups. By integrating fruit morphology and molecular phylogenetic analyses, we preliminary clarified the intricate taxonomic relationships among Tongoloa and related taxa. These results provide valuable opportunities for a deeper understanding of the phylogeny of Tongoloa.

Revealing Greenhouse Gas Emission and Nitrogen Fertilizer Destination: A Case Study in Chengdu Plain Cultivation Industry

The cultivation industry occupies a large proportion of greenhouse gas emissions in agriculture. Assessing greenhouse gas emissions from the cultivation industry is pivotal for mitigating emissions and promoting sustainable cultivation. Utilizing greenhouse gas emission calculation methods recommended by the Intergovernmental Panel on Climate Change (IPCC) and other methods, this work evaluated annual emissions and the emission structure of major crops from 2005 to 2021 in the Chengdu Plain, a significant agricultural region in Southwest China. We identified nitrogen fertilizer as the primary contributing factor to high emissions from cultivation production. Subsequently, we analyzed the trend and utilization of nitrogen fertilizer, which proposes essential strategies for reducing greenhouse gas emissions. The results showed that greenhouse gas (GHG) emissions from the cultivation industry in the Chengdu Plain exhibited a growth, fluctuation, and eventual decline trend from 2005 to 2021. The emissions increased from 5,148,900 t in 2005 to 6,289,700 t in 2009, representing a 22.16% increase, and subsequently decreased to 5,109,900 t in 2021, marking a 23.31% decrease. Nitrogen fertilizer application emerges as the primary source of GHG emissions, constituting approximately half of the total, with nitrogen fertilizer manufacturing contributing significantly as well, collectively amounting to about 70%. We also found that the proportion of greenhouse gas emissions attributed to cash crop cultivation has gradually increased over the last decade. Among these crops, vegetables exhibit the highest emissions, comprising nearly half of the total emissions from 2019 onwards. However, the nitrogen fertilizer use efficiency of cash crops is less than 30%, with higher nitrogen surplus, ammonia volatilization, and nitrogen leaching per unit area, and the total amount is higher than that of grain crops. Among cash crops, vegetables exhibit the highest amount of nitrogen surplus, ammonia volatilization, and nitrogen leaching, constituting nearly half of the total amount in the study area since 2019. Our findings significantly affect sustainable and low-carbon cultivation industry development in the study area.

Short-Term Power Load Forecasting Method Based on GRU-Transformer Combined Neural Network Model

Load Forecast (LF) is an important task in the planning, control and application of public power systems. Accurate Short Term Load Forecast (STLF) is the premise of safe and economical operation of a power system. In the research of short-term power load forecasting, machine learning and deep learning are the most popular methods at present, but there still exists a problem that the single and simple structure of power load forecasting model leads to low accuracy of load forecasting. In order to improve the accuracy of STLF, a Gated Cycle Unit (GRU)-Transformer combined neural network model is proposed. Transformer encoder structure is used as feature extractor to mine the complex mapping relationships between the input features and load. The advantage of self-attention mechanism is used to solve the problem of information loss of long sequences in short-term power load forecasting. At the same time, the multivariate time series model of GRU is used for model training. The experimental results on the power load data set of a certain region in southwest China and Panama City show that the proposed combined model prediction method has higher accuracy than those proposed in other literatures, which further proves its feasibility and superiority.

Effects of Land Use Change on Soil Aggregate Stability and Erodibility in the Karst Region of Southwest China

Differences in land use type and chronological age affect soil properties and plant community characteristics, which may influence soil structural stability and erodibility. However, knowledge on the effects of soil physicochemical properties on soil aggregate stability and erodibility at different land use years is limited. This study selected five land use types: corn field (Year 38th-y), corn intercropped with cabbage field (Year 38th-y + b), fruit and meridian forest (Year 6th-jgl), naturally restored vegetation (Year 6th-zr), and artificial forest (Year 7th-rgl) in the karst landscape of the Chishui River Basin in Yunnan Province. We aimed to identify the influencing factors of soil stability and erodibility under different land use time series. The results indicated that the mean weight diameter (MWD), the geometric mean diameter (GMD), and soil structural stability index (SSI values) were highest in Y6th-zr and lowest in Y7th-rgl. Conversely, the erodibility K value was lowest in Y6th-zr, suggesting that the soil structure in Y6th-zr exhibited greater stability, whereas soil stability in Y7th-rgl was lower. Redundancy and throughput analyses revealed that organic carbon and water-stable aggregates > 2.0 mm content had higher vector values. Soil bulk density, total nitrogen, organic carbon, and soil texture content were the main factors contributing to soil stability variation (0.338–0.646). Additionally, total nitrogen, organic carbon, total phosphorus, and soil texture content drove the variation in K values (0.15–1.311). Natural vegetation restoration measures can enhance soil structure to a certain extent. These findings highlight changes in soil aggregate stability and erodibility over different land use durations. The research results have important theoretical and practical significance for understanding the differences in soil erosion and soil restoration under different land use patterns in the karst landscapes of southwest China.

Identification and characterization of a novel canine circovirus with truncated replicate protein in Sichuan, China.

Canine circovirus (CanineCV) is a recently identified member of the Circoviridae family. Since its discovery in 2011, CanineCV has been detected in different countries worldwide, infecting both domestic and wild canids. The virus is potentially associated with gastrointestinal and respiratory illnesses. In 2016, CanineCV was reported in the southwestern region of Guangxi, China. However, its prevalence in other provinces in the Southwest region remained unknown. This study collected a total of 208 serum samples from domestic dogs in Sichuan, China in 2022 to investigate the prevalence of CanineCV. Among these samples, 26 tested positive for CanineCV, resulting in a positivity rate of 12.5%. Additionally, 12 strains were sequenced, 9 of which had a sequence length of 2,063 nucleotides (nt), 2 of the other threes had a length of 2,062 nts and another was 2,064 nt. Notably, a frameshift mutation was identified, resulting in a truncated ORF1 and the occurrence of a novel sequence comprised of 13 amino acids at the end of the replicate protein (Rep). This mutation could affect the replication cycle of the virus. Phylogenetic and evolutionary analyses revealed that the isolates belonged to the CanineCV-3 genotype and were prevalent in the Southeast and the Southwest regions of China, as well as in the neighboring countries alongside other strains of the same genotype. Collectively, this epidemiological investigation widens our understanding of the genetic diversity of CanineCV in Southwest China and provides insights into viral evolution.

Barriers and facilitators of nurse-led self-management support for adolescents with epilepsy: A mixed-methods study in transition preparation

AimsTo gain insight into the readiness for evidence-based practice of self-management support during transition for adolescents with epilepsy among pediatric nurses, and to explore the promoting and hindering factors. DesignA mixed-methods design with an explanatory sequential approach was employed. SettingThree specialty children's hospitals in southwest regions of China. MethodsIn phase 1, a total of 126 participants were included in the Survey of Clinical Readiness of Evidence-Based Nursing Assessment (CREBNA) from Dec 2022 to Feb 2023. Total scale and subscale scores were calculated. In phase 2, we developed the interview outline based on the analysis of the quantitative results. In-depth interviews (n = 15) were conducted from Feb 2023 to Apr 2023 to explain and supplement the quantitative phase results. ResultsThe total score of CREBNA indicated that teams have good readiness and capacity for implementation of evidence-based nursing practice Compared with the norm. The scores of the three subscales of evidence factors, organizational environment, and promoting factors were normal. In subsequent interviews and integration, we extracted four themes based on the Knowledge-To-Action (KTA) framework: 1. organization barriers (incentive mechanism, interdisciplinary cooperation process, information aids); 2. operational barriers (Exemplary evidence-based practice, time pressure, gaps in patient and family understanding of evidence); 3. individual-level barriers (evidence-based and professional knowledge reserve, professional autonomy, shared decision-making roles, dependence on habitual clinical behaviors); and 4. facilitating factors (leadership commitment, self-management identity, transition service needs, patient- and family-centered care culture). A conceptual model was constructed based on the KTA. ConclusionIt is feasible to carry out evidence-based practice of nurse-led self-management support in transition preparation. Nursing researchers and managers should carry out knowledge selection and tailoring based on barriers at the organizational, operational, and individual levels to promote favorable factors and improve the smooth transition of adolescents with chronic diseases.

Iris luojiensis (Iridaceae), a new species from southwest China

Iris luojiensis Z.Y. Wang, H.W. Huang and R. Li sp. nov. from southwest China is described and illustrated. This species occurs on shrub slopes in mountainous regions of southwest China. Iris luojiensis is morphologically similar to Iris japonica Thunb., Iris calcicola Z. C. Lu, Z.P. Huang and Yan Liu and Iris wattii Baker, but easily distinguished from them by its bluish‐violet flowers, 3–6 flowering‐stem branches, leaf size, particularly the upper leaves, and by only having two to three (seldom one) flowers per bract. A phylogenetic analysis based on the complete plastid genome supports the separation of I. luojiensis from other morphologically related species. According to morphological and molecular evidence, I. luojiensis can be placed in the I. sect. Lophiris.

Deciphering the key factors affecting pesticide residue risk in vegetable ecosystem

Soil contamination, particularly from pesticide residues, presents a significant challenge to the sustainable development of agricultural ecosystems. Identifying the key factors influencing soil pesticide residue risk and implementing effective measures to mitigate their risks at the source are essential. Here, we collected soil samples and conducted a comprehensive survey among local farmers in the Three Gorges Reserve Area, a major agricultural production region in Southwest China. Subsequently, employing a dual analytical approach combining structural equation modeling (SEM) and random forest modeling (RFM), we examined the effects of various factors on pesticide residue accumulation in vegetable ecosystems. Our SEM analysis revealed that soil characteristics (path coefficient 0.85) and cultivation factor (path coefficient 0.84) had the most significant effect on pesticide residue risk, while the farmer factors indirectly influenced pesticide residues by impacting both cultivation factors and soil characteristics. Further exploration using RFM identified the three most influential factors contributing to pesticide residue risk as cation exchange capacity (CEC) (account for 18.84%), cultivation area (account for 14.12%), and clay content (account for 13.01%). Based on these findings, we carried out experimental trials utilizing Integrated Pest Management (IPM) technology, resulting in a significant reduction in soil pesticide residues and notable improvements in crop yields. Therefore, it is recommended that governmental efforts should prioritize enhanced training for vegetable farmers, promotion of eco-friendly plant protection methods, and regulation of agricultural environments to ensure sustainable development.

Optimizing Split-reduced drip fertigation schemes of Arabica coffee based on soil microcosms, bean yield, quality and flavor in dry-hot region of southwest China

As a characteristic cash crop in Yunnan Province, China, Arabica coffee ranks first in the country in terms of cultivation area and production, but has always suffered from poor soil nutrient management and a lack of scientific basis for fertilization. It is not clear how to improve the soil microecological environment using split-reduced drip fertigation at different reproductive stages of Arabica coffee to improve bean yield and quality. Therefore, a two-year (2020–2022) field experiment was conducted on 5-year-old Arabica coffee trees in a dry-hot region with five split-drip fertigation patterns, F450, F600, F750, F900 and F1050. Using the local conventional fertilization (Fertilizer of 900 kg ha−1 year−1 only in berry expansion, and no fertilization in early flowering and berry ripening) as the control (CK). The effects of different fertilization modes on soil microecological environment, bean yield, nutritional quality and characteristic flavor were studied, and a comprehensive benefit evaluation model to assess bean yield and nutritional quality under different fertilization modes was established. The results showed that F900 significantly increased soil nitrate nitrogen, available phosphorus, available potassium, microbial population and enzyme activities at early flowering and berry ripening stages compared to CK, while F900 reduced soil nitrate nitrogen, available phosphorus and available potassium but increased soil enzyme activity and microbial population at the berry expansion stage. Compared with CK, F450 decreased bean yield, caffeine and chlorogenic acid content by 31.83 %, 23.73 % and 13.48 %, respectively, while F750 increased two-year average yield, raw bean fat, caffeine and chlorogenic acid content by 20.52 %, 12.37 %, 5.48 % and 11.17 %, respectively. The two-year average yield of F600 showed less difference from CK. Marginal yield was positive and then negative with increasing fertilizer application. Dry bean yield decreased at a total fertilizer application of 900 kg ha−1 year−1. Correlation analyses showed a positive correlation between soil microbial environment and nutrient quality of coffee beans, while different correlations were found between nutrients and volatiles at dark and medium roasting levels. Cluster analysis revealed that the relative contents of aldehydes, alcohols, phenols, pyridines, and pyrroles were higher under dark roasted condition, while the relative contents of ketones, esters, acids, and pyrazines were higher under medium roasted condition. Based on the Entropy weight-TOPSIS method, F750 had the highest combined benefits in terms of yield increase and quality improvement, and the total fertilizer application decreased by 16.67 % compared to CK, thus F750 treatment was the most suitable split-drip fertigation strategy for Arabica coffee in the dry-hot region of Yunnan. This study provided a reference for drip fertigation systems of Arabica coffee in dry and hot regions.

Exploring new discoveries of steel fining in a Western Han Dynasty city in southwest China: A case study of steel fining remains excavated from the ancient Xindu city in Sichuan Province

AbstractArchaeological discoveries and historical documents show that the Chengdu Plain was the most important iron production center in the southwest region of China during the Qin and Han dynasties. However, due to the lack of archaeological evidence, the iron production technology of cities in the Chengdu Plain during the Qin and Han dynasties remains unclear. The Xindu city site is located in Qingbaijiang District, Chengdu Sichuan Province. It was an important city site in the Chengdu Plain during the Han and Jin dynasties. During excavation of the Xindu city site, archaeologists unearthed a large number of metallurgical remains such as slags and tuyeres, as well as two severely damaged hearth bases near the western city wall. Scientific analysis results suggest that the metallurgical remains are related to the steel fining process and could be dated back to the Western Han Dynasty. The metallurgical remains in the Xindu city are the earliest known artifacts associated with the steel fining process in southwest China. This discovery also marks the first identification of iron industry workshops in a Han Dynasty city in the Chengdu Plain. The findings reveal a different industrial layout pattern from previously discovered Han Dynasty metallurgical sites in the Chengdu Plain. Additionally, this discovery provides archaeometallurgical evidence for the central government's development in southwest China during the Han Dynasty.

Form, Bioavailability, and Influencing Factors of Soil Selenium in Subtropical Karst Regions of Southwest China

Form, Bioavailability, and Influencing Factors of Soil Selenium in Subtropical Karst Regions of Southwest China

Phylogeographic Structure and Population Dynamics of Baoxing Osmanthus (Osmanthus serrulatus), an Endemic Species from the Southwest Sichuan Basin, China.

The mountainous regions of southwest China are recognized as pivotal centers for the origin and evolution of Osmanthus species. Baoxing Osmanthus (Osmanthus serrulatus Rehder), a rare and endemic species known for its spring blooms, is sparsely distributed within the high altitude evergreen broad-leaved forests surrounding the southwestern Sichuan Basin. However, persistent anthropogenic disturbances and habitat fragmentation have precipitated a significant decline in its natural population size, leading to the erosion of genetic resources. To assess the genetic status of O. serrulatus and formulate effective conservation strategies, we conducted sampling across ten wild populations, totaling 148 individuals in their natural habitats. We employed two cpDNA fragments (matK and trnS-trnG) to elucidate the phylogeographic structure and historical population dynamics. The results revealed low species-level genetic diversity, alongside pronounced regional differentiation among populations (FST = 0.812, p < 0.05) and a notable phylogeographic structure (NST = 0.698 > GST = 0.396, p < 0.05). Notably, genetic variation was predominantly observed among populations (81.23%), with no evidence of recent demographic expansion across the O. serrulatus distribution range. Furthermore, divergence dating indicated a timeline of approximately 4.85 Mya, corresponding to the late Miocene to early Pleistocene. This temporal correlation coincided with localized uplift events in the southwestern mountains and heightened Asian monsoons, suggesting pivotal roles for these factors in shaping the current phylogeographic pattern of O. serrulatus. These findings support the effective conservation of O. serrulatus germplasm and offer insights into the impact of Quaternary climate oscillations on companion species within evergreen broad-leaved forests. They also enhance our understanding of the origin and evolution of these forests in the southwestern mountains, aiding biodiversity conservation efforts in the region.