Southwest Region Of China Research Articles

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.

Improving dynamical-statistical subseasonal precipitation forecasts using deep learning: A case study in Southwest China

Subseasonal precipitation forecasting is challenging but critical for water management, energy supply, and disaster prevention. To improve regional subseasonal precipitation prediction, previous studies have proposed a dynamical-statistical projection model (DSPM). In this study, we develop a new method that combines the DSPM and deep learning (DL), called the DL-DSPM. The DSPM is developed using the observed relationships between large-scale atmospheric circulations and regional precipitation, and the dynamical forecasted atmospheric circulations from the European Centre for Medium-Range Weather Forecasts (ECMWF) model. The DL-DSPM improves upon the DSPM by correcting biases in atmospheric circulation forecasts from the ECMWF model using two DL models, namely, residual network and U-Net models. In the case of Southwest China (SWC), DL models can improve atmospheric circulation forecasts at lead times beyond 5 pentads, including large-scale drivers of SWC precipitation variability. The DL-DSPM outperforms the ECMWF model and DSPM forecasts in predicting precipitation anomalies beyond 4 and 5 pentads over most SWC regions, respectively. In addition, the DL-DSPM is more skillful than the ECMWF model and DSPM in predicting extreme precipitation events more than 4 pentads in advance. The successful combination of DL and the DSPM provides a new possible direction for DL applications in subseasonal precipitation forecasting.

Effects of vegetation degradation on soil microbial communities and ecosystem multifunctionality in a karst region, southwest China

Vegetation degradation caused by intense human disturbances poses a significant challenge to the preservation and improvement of ecosystem functions and services in the karst region of southwest China. Soil microorganisms are major regulators of ecosystem multifunctionality (EMF). Currently, there is a dearth of knowledge regarding the effects of vegetation degradation on soil microbial communities and their corresponding multiple ecosystem functions in karst regions. In this study, we selected the vegetation degradation sequences of second natural forest (NF), agroforestry (AS) and cropland (CL) to investigate the diversity of bacterial, fungal and protistan communities, and their hierarchical co-occurrence network, and EMF to explore the relationships between them. Compared to the NF, the carbon cycling index, nitrogen cycling index, soil water regulation power, and the EMF were significantly decreased by 8.2%–50.6%, 48.7%–86.8%, 19.8%–24.5%, and 31.4%–69.5% in the AS and CL, respectively. The development of EMF can be explained by the fungal, protistan and microbial hierarchical β-diversity, as well as the complexity (e.g. degree) of microbial hierarchical interactions during the process of vegetation degradation. Notably, correlations between the abundances of sensitive amplicon sequence variants (sASVs) for different karst vegetation types and EMF varied in distinct network modules, being positive in module 1 and negative in module 2. Moreover, the relative abundance of keystone taxa in fungal and protistan communities provided greater contributions to EMF than the bacterial communities. Additionally, random forest modeling showed that carbon and nitrogen sources, and soil water content, and trace elements (e.g. exchangeable magnesium, iron, manganese, and zinc) were identified as key driving factors of the EMF. Collectively, our findings demonstrate that vegetation degradation obviously alters soil microbial diversities and hierarchical interactions, emphasizing their key role in maintaining ecosystem functions and health in karst regions.

Towards Achieving Carbon Neutrality: The Role of Vegetation Restoration in Karst Regions of Southwest China

Towards Achieving Carbon Neutrality: The Role of Vegetation Restoration in Karst Regions of Southwest China

Effects of vegetation restoration on the temporal variability of soil moisture in the humid karst region of southwest China

Study regiona typical humid karst region of southwestern China. Study focusTemporally stable soil moisture variability (SMV) helps clarify stress on vegetation growth. In the humid karst region of southwest China, large-scale vegetation restoration has affected the soil moisture. However, most studies here have focused on changes in the soil moisture content, and changes in the SMV have not been considered. New hydrological insights for the regionIn this study, changes to the SMV after vegetation restoration were analyzed using two indicators: the soil moisture coefficient of variation(SMCV) and soil moisture memory(SMM). The results showed that the SMCV decreased by an average of 22.3 % and the SMM increased by an average of 17.2 % in the Karst region of southwest China. the SMV had significantly decreased after vegetation restoration, and the overall decrease was larger on 15-day, monthly, and yearly scales and smaller on the weekly scale.When the effects of different vegetation types were considered, SMV greatly decreased in forestland and grassland on the 15-day and monthly scales, in shrubland on the annual scale, and in sparse woodland on the 15-day, monthly, and annual scales. Four geomorphic regions in particular showed large reductions in the SMV: the karst basin, peak cluster depression, peak forest plain, and non-karst region. In addition, changes in SMV after vegetation restoration have a significant positive influence on geochemical and climatic factors and a non-significant negative influence on geological structure factors. Among them, the significant influence factors of CaO content and MgO content are greater than SiO2 content by 0.71 and 0.63. precipitation and temperature are greater than vapor pressure difference by 0.51 and 0.4. Overall, vegetation restoration was found to make the SMV in the humid karst region more stable.

Monitoring spatio-temporal dynamics of multi-dimensional karst ecosystem quality in Southwest China by integrating multi-source data

ABSTRACT A thorough assessment of the karst ecosystem quality plays an important role in regional sustainable development. In this study, based on multi-source remote sensing data, a comprehensive ecosystem quality index (EQI) was developed by integrating the ecosystem function index (EFI), the ecosystem stability index (ESI), and the ecosystem stress index (ESSI), to evaluate the spatio-temporal changes of ecosystem quality in the karst region of Southwest China during the past two decades. The results showed that the EFI exhibited a significant increasing trend in approximately 54.58% of the karst area from 2001 to 2020. The ESI experienced multiple stages from initially increasing around 2005, then decreasing around 2010, and finally increasing to the peak in 2020. The ESSI fluctuated at a high level since 2001. Overall, the comprehensive EQI experienced a gradual improvement in the initial period from 2001 to 2010, and then increased significantly from 2015 to 2020. The excellent EQI occupied by no more than 20% before 2005, but expanded sharply with about three times by 2020. Additionally, nearly 16.73% of the karst area experienced significant improvement in the EQI, whereas only 0.28% of the karst area exhibited severe degradation in the EQI during the past 20 years.

A study on soil aggregate stability and splash erosion under exogenous electrolyte conditions in the karst region of Southwest China

Study areaKarst region in Guangxi Province, Southwest China. Study focusBoth soil properties and rainfall characteristics have a critical influence on splash erosion and aggregate stability. However, the impact of electrolytes on splash erosion has received less attention. In this study, soils from 4 typical land use types (cropland, orchard, artificial forest and secondary forest) in karst region were utilized as the research objects. NaCl, KCl, and MgCl2 solutions of different concentrations were used to determine the stability of the aggregates via fast wetting (FW) treatment of Le Bissonnais (LB) method and the characteristics of splash erosion via simulated rainfall experiments. New hydrological insights for the regionResults revealed that both the land use types and electrolyte significantly influenced the soil aggregate stability and splash characteristics. Specifically, the change in land use from cropland to orchard, artificial forest and secondary forest significantly increased the aggregate stability, thus decreasing soil erodibility. The aggregate stability decreased and the total splash rate increased as the electrolyte concentration increased. The total splash erosion rate of the 4 soils was positively correlated with the <0.5 mm particle size released by aggregate fragmentation under simulated rainfall conditions. The results can provide a theoretical basis for soil erosion control and soil quality improvement in the karst region of Southwest China.

Understanding ethnic minority students’ motivations to pursue higher music education over time

This longitudinal case study aimed to explore changes in ethnic minority students’ motivations to pursue higher music education during the transition from high school to university. The participants were recruited from the Yi, Mongolian and Tibetan ethnic groups in a remote mountainous region of southwest China. Data were collected through participant observation and semi-structured interviews. The findings of the study indicated that the ethnic minority students were driven both by intrinsic motivations, including a love of and interest and persistence in music, positive musical experiences and musical ability, and by extrinsic motivations, including the desire to earn a university degree by way of studying music, meet the expectations of their local music teachers and family members and repay their hometowns by serving as local music teachers. However, most of the participating ethnic minority students exhibited a shift in their motivations to study music after 2 years of university education. This shift was attributable to various elements, including peer competition, employment pressure, mentor support and the university environment. Based on these findings, we suggest ways to support ethnic minority students transitioning smoothly from high school to university and continuing their music studies.

How are social context factors related to epistemological beliefs, motivations, and achievement in science? A serial mediation model

ABSTRACT Background Epistemological beliefs and motivational factors are significant predictors of achievement in science. Purpose To understand how social context factors shape epistemological beliefs and motivational factors and how they pass the influences to achievement in science. Sample A population of ninth graders in an underdeveloped region of southwest China (N = 2655). Design and Methods With science achievement test scores and survey data from the sample, we built a structural equation model on how the students’ epistemological beliefs and motivational factors mediate the effects of a set of social context factors on their achievement in science. Gender and rural-urban differences are also explored. Results Intrinsic motivation and epistemological beliefs significantly predicted achievements in science. Epistemological beliefs directly and indirectly affected achievement in science, with intrinsic motivation mediating its indirect effects. Among the social context factors, teacher influence and informal learning experiences positively predicted epistemological beliefs; family encouragement negatively predicted epistemological beliefs; only informal learning experiences directly affected intrinsic motivation. Significant rural-urban and gender differences were found. Conclusion Access to informal science learning experiences can play a crucial role in transforming the social environments in underdeveloped regions, promoting students’ epistemological development and intrinsic motivation, and, in turn, their achievement in science. Fostering students’ epistemological development may also require identifying and reconciling the conflicts between epistemological messages from home and school.

International intelligibility of English spoken by college students in the Bashu dialect area of China

Exploring English intelligibility in linguistically diverse environments, such as China, is crucial for improving cross-cultural dialog and tailoring language instruction to address the phonetic hurdles of non-native speakers. This research employed a phonetic experimental methodology to assess the intelligibility of English spoken by college students from the Bashu dialect region of Southwest China to an international audience. Data from 40 intermediate English-proficient students in Sichuan and Chongqing were analyzed using open-ended questionnaires and evaluative scales. The findings revealed that the influence of the Bashu dialect significantly impeded the accurate articulation of specific English phonemes, thereby exerting an impact on the international intelligibility of their spoken English. Notably, notwithstanding their conspicuous accents, the research concluded that the English enunciated by these students generally retained intelligibility for global audiences. The study identified a spectrum of pronunciation challenges, encompassing issues with phonetic sounds, recurrent mispronunciations, and variances in accent and prosody, collectively contributing to an overarching influence on intelligibility. Grounded in international listener feedback, this study proffers strategies to augment the intelligibility of spoken English among Chinese learners originating from dialect-specific regions, thereby fostering the amelioration of their communicative skills and bolstering their confidence when engaging with global audiences.

Novel Alkaloids from Aspergillus fumigatus VDL36, an Endophytic Fungus Associated with Vaccinium dunalianum.

Eleven alkaloids (1-11) including seven new ones, 1-7, were isolated from the solid fermentation of Aspergillus fumigatus VDL36, an endophytic fungus isolated from the leaves of Vaccinium dunalianum Wight (Ericaceae), a perennial evergreen shrub distributed across the Southwest regions of China, Myanmar, and Vietnam. Their structures were elucidated on the basis of extensive spectroscopic methods. The isolates were evaluated for in vitro antifungal activities against five phytopathogenic fungi (Fusarium oxysporum, Coriolus versicolor, Fusarium solani, Botrytis cinerea, Fusarium graminearum). As a result, the new compounds fumigaclavine I (1), 13-ethoxycyclotryprostatin A (5), 13-dehydroxycyclotryprostatin A (6), and 12β-hydroxy-13-oxofumitremorgin C (7) exhibited antifungal activities with MIC values of 7.8-62.5 μg/mL which were comparable to the two positive controls ketoconazole (MIC = 7.8-31.25 μg/mL) and carbendazim (MIC = 1.95-7.8 μg/mL). Furthermore, compounds 1 and 5 demonstrated potent protective and curative effects against the tomato gray mold in vivo. Preliminary structure-activity relationships of the tested indole diketopiperazine alkaloids indicate that the introduction of a substituent group at position C-13 enhances their biological activities.

The impact of natural vegetation restoration on surface soil moisture of secondary forests and shrubs in the karst region of southwest China

AbstractSoil moisture is crucial to vegetation restoration in karst areas, and climate factors and vegetation restoration are key factors affecting changes in soil moisture. However, there is still much controversy over the long‐term changes in soil moisture during vegetation restoration. In order to reveal the changes in soil moisture during vegetation restoration, we conducted long‐term positioning monitoring of soil moisture at 0–10 and 10–20 cm on secondary forests sample plot (SF, tree land) and shrubs sample plot (SH, shrub land) in karst areas from 2013 to 2020. The results showed that the aboveground biomass of SF and SH increased by 50% and 240%, respectively, and the soil moisture of the SF and SH showed an increasing trend. When shrubs are restored to trees in karst areas, the soil moisture becomes more stable. However, the correlation coefficients (R2) between the annual rainfall and the annual average soil moisture of SF and SH are 0.84 and 0.55, respectively, indicating that soil moistures in tree land are more affected by rainfall. The soil moisture of shrubs and trees are relatively low during the months of alternating rainy and dry seasons. Rainfall has a very significant impact on the soil moisture of tree land, while air temperature and wind speed have a significant impact on the soil moisture of tree land, but the soil moistures of shrub land are very significantly affected by rainfall and relative humidity. Therefore, during the process of vegetation restoration from shrubs to trees, the main meteorological factors that affect soil moisture changes will change. The results are important for understanding the hydrological processes in the ecological restoration process of different vegetation types in karst areas.

A comparison of preferential flow characteristics and influencing factors between two soils developed in the karst region of Southwest China

A comparison of preferential flow characteristics and influencing factors between two soils developed in the karst region of Southwest China

Effects of Straw Returning on Soil Aggregates and Its Organic Carbon and Nitrogen Retention under Different Mechanized Tillage Modes in Typical Hilly Regions of Southwest China

Tillage modes and straw returning influence soil aggregate stability and the distribution of organic carbon (C) and nitrogen (N) in aggregates of different particle sizes. In the typical hilly regions of southwest China, the predominant soil type is purple soil, characterized by heavy texture and high stickiness, with relatively lower soil fertility compared to other soil types. The improper use of fertilizers and field management practices further exacerbates soil compaction. However, abundant straw resources in the region provide an opportunity for comprehensive straw utilization. The effective utilization of straw resources is of significant importance for stabilizing agricultural ecological balance, improving resource utilization efficiency, and alleviating ecological pressure. Previously, most studies have focused on the impact of different mechanized tillage systems on the physical and chemical properties of soil in hilly areas, while research on the preservation of water-stable aggregates’ organic C and N content remains limited. In this study, the soil properties of fields under a winter pea–summer corn rotation for two years were studied with regards to the effects of straw returning on its water-stable aggregate distribution, macroaggregate content (R0.25), mean weight diameter (MWD), geometric mean diameter (GMD), and the organic C and N content in soil aggregates of different particle sizes and at different depths. The effects of five different tillage modes were assessed, namely rotary tillage with straw mixed retention (RTM), conventional tillage with straw burial retention (CTB), no-tillage with straw covered retention (NTC), subsoiling with straw covered retention (STC), and no-tillage without straw retention (NT). Based on the study results, under different tillage modes, straw returning effectively enhanced the soil organic carbon (SOC) and total nitrogen (TN) reserves at the plow layer (0–30 cm), SOC increased by 17.2% to 88%, and TN increased by 8.6% to 85.9%. At the same time, the content of 0.25–2 mm aggregates increased under the straw-return treatments under different tillage patterns. The NT treatment had the lowest R0.25 and MWD and GMD values for soil aggregates at different depths, which were significantly different (p &lt; 0.05) from the other treatment modes. The correlation coefficients between SOC and soil aggregate stability indices ranged from 0.68 to 0.90, with most of them showing highly significant positive correlations (p &lt; 0.01). In conclusion, straw returning under different tillage systems has improved soil aggregate stability and promoted soil structure stability. Specifically, the STC treatment has shown more pronounced effects on soil improvement in the upper soil layer of the hilly regions in southwest China, while the RTM treatment is beneficial for improving the lower soil layer. Therefore, the comprehensive experimental results indicate that the combination of STC and RTM treatments represents the most promising mechanized tillage and straw returning practices for the hilly regions in southwest China.

Mapping Cropland Abandonment in the Cloudy Hilly Regions Surrounding the Southwest Basin of China

Cropland is a vital resource intricately connected to food security. Currently, the issue of cropland abandonment poses a serious threat to food production and supply, presenting a significant challenge to rural economies and the stability of the food supply chain. The hilly and cloudy regions of southwest China are particularly affected by cropland abandonment, presenting significant challenges in accurately mapping the distribution of abandoned cropland due to fragmentation and heavy cloud pollution. Therefore, this study focuses on Mingshan County, located in Ya’an City, Sichuan Province, China, as the study area. Utilizing Google Earth Engine (GEE) and a random forest algorithm, a method integrating multi-source data from Landsat 8, Sentinel-2, and Sentinel-1 is proposed to extract abandoned cropland spanning from 2018 to 2022. This study analyzes spatial and temporal characteristics, employing the Geodetector with optimal parameters to explore the underlying mechanisms. The findings reveal the following: (1) The method achieves an overall accuracy of land use classification surpassing 88.67%, with a Kappa coefficient exceeding 0.87. Specifically, the accuracy for identifying abandoned cropland reaches 87.00%. (2) From 2018 to 2022, the abandonment rate in Mingshan County fluctuated between 4.58% and 5.77%, averaging 5.03%. The lowest abandonment rate occurred in 2019–2020, while the highest was observed in 2020–2021. (3) Cropland abandonment is influenced by both natural and social factors. Elevation and slope are the main driving factors, alongside factors such as distance to road, town, and residential settlement that all significantly contribute to abandonment trends. These five factors exhibit positive correlation with the abandonment rate, with distance to the river showing relatively weaker explanatory power.

Quantifying the water use efficiency of karst ecosystems and response to environmental factors

Study regionThe study area is located in Guizhou province, the centre of the karst region in southwest China. Study focusAs a typical karst region, Guizhou has long faced challenges with water scarcity. Quantifying water use efficiency (WUE) is crucial for the efficient use of water resources and sustainable management. This study examined the spatio-temporal evolution patterns and its driving factors on WUE in Guizhou using Theil-Sen's slope, partial correlation methods, and the geographic detector model. New hydrological insights for the region(1) The multi-annual mean WUE of non-karst region (NKR, 2.75 gC kg−1 H2O yr−1) is higher than that of karst region (KR, 2.10 gC kg−1 H2O yr−1) during 2001–2020. (2) The rate of increase of WUE was three times higher in KR than in NKR. (3) Precipitation and temperature were identified as the key factors influencing WUE. Interactions between each environmental factors were observed to have both bi-variate and non-linear enhancement effects. Notably, in the NKR, soil moisture, vegetation type and leaf area index were the dominant factors influencing WUE, with interactions between environmental factors had both enhanced and weakened effect on WUE. (4) The synergistic effects of these interactions exceeded the individual or cumulative effects of the two environmental factors. These findings contribute to our understanding of the environmental factors driving changes in WUE in the KR.

Comprehensive assessment of rocky desertification treatment in Southwest China karst

AbstractRocky desertification is a prominent ecological issue in Southwest China's karst region, ranking among the nation's three primary ecological challenges alongside soil erosion and desertification. The government initiated the Rocky Desertification Treatment Program in 2008, lacking a comprehensive evaluation of its benefits. This study evaluates the program's impact on ecosystem services over the last two decades using remote sensing, ecosystem models, and field data. The results indicated a continuous net decrease of rocky desertification, 48% in the eight southwestern provinces from 2005 to 2021. The average annual growth rate of vegetation cover reached 2.54% in key counties for rocky desertification control, significantly higher than that of all the 451 rocky desertification counties from 2016 to 2020. Additionally, ecosystem productivity increased by 35.8% in rocky desertification counties from 2000 to 2020, which is 1.34 times greater than that observed in non‐rocky desertification counties. It was found that the ecosystem service promotion after the net reduction of rocky desertification area in 2010–2020 is more significant, especially the carbon sequestration in 2010–2020 of key counties for rocky desertification control is 2.7 times than that in 2000–2010. It indicates that the rocky desertification treatment enters the stage of ecosystem service promotion on the basis of achieving rapid “greening,” leading to significant improvements in ecosystem structures and services in the karst region of Southwest China. To mitigate the risk of rocky desertification, tailored measures must be implemented considering local climate, lithology, landform types, and human–land relations for effective treatment zoning and classification.

Influence of Land Use Types on Soil Properties and Soil Quality in Karst Regions of Southwest China

Establishing a suitable and useful soil quality index (SQI) is the key to accurately evaluating changes in soil quality (SQ) under different land use types. In the present study, a suitable and useful SQI using a minimum data set (MDS) with two scoring methods (linear scoring method and nonlinear scoring method) and two additive models (simple additive model with same weighting value and weighted additive model with significant different weighting value) was established to compare SQ under different land uses in Longtan valley. Soil samples were collected under one dryland (DRYL), one paddy (PADD), one orchard (GRA), and one natural forest (FORE), and 13 soil properties were measured. The four land use types had the same soil type and similar environmental conditions. Land use types had significant effects on the measured 12 soil properties. The top two principal components in Principal Component Analysis were chosen, and their cumulative variance was more than 90%. Soil indicators of soil labile carbon, C/N ratio, and microaggregates were chosen as members of MDS in this study. Significant (p &lt; 0.001) positive correlations among the four establishing SQIs were found. The values of the sensitive index ranged from 47.17% to 82.12% for the four SQIs, and the SQI established using the nonlinear scoring method and weighted additive model (SQI-NLW) had the highest values. Among the four land use types, the four SQIs had similar change trends, and the average values of SQ under FORE (0.73) and PADD (0.68) were significantly higher than those under GRA (0.54) and DRYL (0.43). These results indicated that the SQI-NLW was an effective and precise tool to assess SQ under different land uses in similar regions, and the FORE and PADD were the suitable land use types for the sustainable use of soils in karst regions.

Optical properties and molecular compositions of dissolved organic matter in multiple runoff components during rainfalls on the karst hillslope

Understanding the chemical composition, origin, and molecular structure of dissolved organic matter (DOM) in multi-interface runoff is essential for comprehending the fate of laterally transported DOM in complex soil-epikarst systems of karst hillslopes. Limited information, however, is available for the optical properties and molecular compositions of the transported OM in multiple runoff components on the karst hillslope in relation to land-uses and soil thicknesses. In this study, we conducted a study to observe the changes in the quantity and quality of DOM in multiple interface flow (surface, subsurface, and epikarst) during natural rainfall events in 2022 in karst hillslopes that are covered by different land uses (cropland and shrubland) and soil thicknesses (with mean depths of 66.0 cm for deeper soil and 35.4 cm for shallower soil) in the karst region of southwest China. chemcial compositions of runoff DOM were determined by optical analysis and microbial compositions in runoff were inferred with high-throughput sequencing. The results showed that the soil-epikarst structure was controlling the runoff DOM quantity and quality during rainfall events. A decrease in the aromaticity, humification, unsaturation, and oxidation degree and an increase in carbohydrate, aminosugars, protein, and lipid compounds were found from surface to epikarst flow, indicating that plant-and soil-derived carbon decreased, while the microbially-derived carbon increased. The results were further comfirmed by the higher bacterial richness and diversity, along with fungal diversity in the epikarst flow compared to other runoff components. The bio-labile protein materials (C2) were the most important component of runoff DOM output in karst hillslopes. In surface and subsurface flow, rainfall amount, runoff rate, and discharge significantly affected the DOM concentration and quality during rainfalls, indicating that the dynamics of DOM in runoff from karst hillslopes were predominantly influenced by hydrological processes. Furthermore, the runoff DOM quality in cropland was dominated by lower unsaturation and oxidation degrees and higher protein component, compared to those in shrubland. The compositions of DOM in runoff from hillslope plots with thicker soils were primarily characterized by microbially-derived materials. Our findings were conducive to understanding the mechanism governing the migration of DOM quality and quantity in discharge during multi-interface hydrological processes on karst hillslopes.