Mountainous Area Of Southwest China Research Articles

Distribution Pattern of Species Richness of Endemic Genera in Mountainous Areas of Southwest China and Its Influencing Factors

China’s southwest mountainous region is one of the hotspots of biodiversity in the world. However, the study on the pattern of species richness distribution of endemic plants in this region and its influencing factors is still in the exploration stage. A clear regional spatial distribution pattern of plants and its influencing factors are very important for the protection and management of plant diversity in southwest China. In this study, 511 county-level regions in the southwest mountainous region were taken as examples to establish a plant species resource bank in the southwest mountainous region, and the distribution pattern of the proportion and abundance of endemic plant families and genera was analyzed based on 19 climate and environmental factors and 8 human disturbance factors in the southwest mountainous region. The geographical weighted regression model (GWR) was used to reveal the main factors affecting the spatial distribution of species. The results showed that: (1) A total of 4688 species investigated in the southwest mountain belong to 19 families and 32 genera. (2) The endemic species richness in the southwest mountainous region showed a significant uneven spatial pattern, mainly concentrated in the Heng Duan Mountain area, southwest Sichuan and northern Yunnan area, and the Ruoergai-Hongyuan area of West Sichuan Plateau. (3) The results of the GWR model showed that the diurnal mean temperature range, precipitation seasonality and distance from the main road had significant effects on species richness. The study on the distribution of endemic genera and their influencing factors in the southwest mountainous region has important implications for the exploration of the evolutionary history and species conservation of the mountain flora.

Coupling effect of impoundment and irrigation on landslide movement in Maoergai Reservoir area revealed by multi-platform InSAR observations

The mountainous areas of Southwest China are crucial regions for hydropower resource development. The unique geological environment and numerous constructed hydropower stations make landslides the primary geological hazard for the region. Therefore, the deformation monitoring and mechanism analysis of reservoir landslides have attracted extensive attention from the academic community. The Maoergai Reservoir (MEGR) is located in the middle reaches of the Heishui River in Sichuan Province, China. Following impoundment, numerous active slopes have arisen in the reservoir area, with the Xierguazi-Mawo landslide complex (XMLC) potentially being the most threatening. In this paper, we first acquired the surface displacement of the MEGR area, before and after impoundment, using time series Synthetic Aperture Radar Interferometry (InSAR) analysis of the ALOS-1/PALSAR-1, ALOS-2/PALSAR-2 and Sentinel-1 datasets. Then, the three-dimensional (3D) deformation field was inverted by combining multi-track InSAR observations and a topography-constrained model. Results show the presence of 47 active landslides within the 675 km2 reservoir area, a significant increase compared to the seven landslides identified prior to impoundment. Based on the derived 3D velocity vectors, we found that the motion of the XMLC exhibits heterogeneity in terms of spatial and temporal patterns. Further, the displacement time series of all detected active landslides suggests that irrigation and water level fluctuations are two major factors influencing the kinematic behaviors of landslides. Irrigation accelerates landslide movement and thus permanently alters the deformation trend, while water level fluctuations cause seasonal oscillations in the displacement time series with a time lag of approximately 100 days. The above results can contribute to landslide management and prevention in the MEGR area and provide a representation for numerous water reservoirs in southwest China.

Spatial Patterns, Drivers, and Sustainable Utilization of Terrace Abandonment in Mountainous Areas of Southwest China

Sloping farmland abandonment has become a typical land use pattern worldwide. Along with the aggravation of sloping farmland abandonment, terrace abandonment is also showing an increasing trend. Systematically clarifying the pattern and mechanism of terrace abandonment is a prerequisite for effective management. Based on the survey data of 145 villages, 697 rural households, and satellite remote sensing in Southwest China, this study uses spatial analysis and the Logit model to reveal the scale, pattern, and driving mechanism of terrace abandonment in the study area to provide scientific references for the sustainable utilization of terrace resources in mountainous areas. This study found that in the study area, 63% of the villages had experienced terrace abandonment, and nearly one-fifth of the rural households had abandoned terraces. The area of abandoned terraces accounted for 7.65% of the total area, and the scale of abandoned terraces reached 449,360 hectares, of which Chongqing has the highest proportion of terrace abandonment (11.5%), while Yunnan Province has the lowest (5.1%); the overall abandoned terraces show a pattern of higher in the east and lower in the west. Terrace abandonment is influenced by multiple factors. The rise in non-agricultural wages attracts rural labor migration as an external force, while the rising operating costs of mountain agriculture serve as internal drivers. Under the combined influence of internal and external factors, the abandonment of terraces in southwest mountainous areas is intensifying. The government should actively conduct assessments of terrace resources within the region and implement targeted measures to address terrace abandonment.

Agroecosystem transformation and its driving factors in karst mountainous areas of Southwest China: The case of Puding County, Guizhou Province

With the rapid socioeconomic development and urbanization, global agroecosystems (AESs) have undergone varying degrees of transformation, and conducting an in-depth study on how AESs are transforming in karst mountainous areas (KMAs) is essential. To further reveal the transformation process of AESs in KMAs, we proposed a theoretical framework for the transformation of AESs in KMAs. Following a “theory construction–empirical analysis–pattern evolution–mechanism revelation” research methodology, we studied the trend of AES evolution in “typical study area—typical landforms of the study area,” summarized the transformation patterns of AESs in different karst landforms, and analyzed the influencing factors of their transformation. The study found that (1) a large amount of productive land (PL) was abandoned as ecological land (EL) on steep slopes at high altitudes in KMAs, while river valleys are dominated by the transformation of PL into ecological and economic land (EEL), and the spatial distribution structure has evolved into a coordinated distribution of EL–EEL–PL, with the dominance of the production function transformed into the dominance of ecological and eco-economic functions and the living function strengthened. (2) The transformation of AESs in different karst landscapes can be summarized into four types: eco-economic development, food supply, ecological conservation, and living service. (3) The transformation of AESs is influenced by various factors, including the region's particular natural environment and socioeconomics. This study also shows that traditional extensive agriculture is moving toward modern intensive agriculture with remarkable ecological and economic win–win benefits. Our study provides theoretical guidance for land remediation, ecological environment restoration, and agricultural transformation in KMAs and similar mountainous areas to alleviate regional human–land conflicts and promote sustainable agricultural development in KMAs.

A Case Study for Stability Analysis of a Toppling Bank Slope with Fault Fracture Zones Developed under the Action of Bridge Loads and Reservoir Water

The mountainous areas of Southwest China have the characteristics of valley deep-cutting, a large topographic gradient, complex geological structures, etc. With the development of infrastructure construction in the area, the construction of bridges across valleys has gradually increased, and the phenomenon of slope failure occurs more and more frequently. As the weak interlayer, the fault fracture zones have a significant influence on the geological structure and stability of slopes, while the complexity of the mechanism of the deformation and failure of slopes increases with the combination of the development of the fracture zones and toppling deformation. This paper took the toppling bank slope of bridge foundations developed with fault fracture zones in Lancang River as the research object. Through an on-site field survey and geological survey technologies, it identified the distribution range of the fracture zones on the bank slope and determined the characteristics of the rock mass in the fracture zones. A stability evaluation model for the bank slope of the bridge foundations was established using the limit equilibrium method and discrete element method. Based on the two-dimensional limit equilibrium analysis, the potential failure modes of the bank slope were explored, and the stability of the bank slope under bridge loads was calculated. Through the three-dimensional geological model of the bank slope, including the fracture zones and toppling bodies, the three-dimensional discrete element numerical simulation method was adopted to simulate and calculate the deformation and failure process of the bank slope under different bridge loads and working conditions. According to the calculation results, the influence of bridge loads and reservoir water on the stability of the bank slope was analyzed from the perspectives of displacement, plastic zone, stability coefficient, and other factors. The formation process of the plastic zone and the development of the sliding surface were revealed, the incentive mechanism of bridge loads and reservoir water on the deformation and failure of the bank slope was analyzed, and the influence of fault fracture zones on the stability of the bank slope and the development of toppling deformation was determined. The results indicate that the fault fracture zones are important geological structures that affect the deformation and failure of the bank slope as a weak interlayer. Under the influence of bridge loads and reservoir water, the stability of the bank slope is affected by the quality of the rock mass and the development of the fault fracture zones, resulting in the unmet need for safety requirements and maybe leading to instability. Based on the calculation results of the stability evaluation prediction model for the bridge foundation bank slope and the engineering geological conditions, the bridge scheme has been selected.

Featured Front Cover

The cover image is based on the Research Article Spatiotemporal evolution and driving mechanism of slope cultivated land in karst mountainous areas of Southwest China—A case study of Puding County, Guizhou Province by Limin Yu et al., https://doi.org/10.1002/ldr.4936.image

Study of the damage characteristics and corrosion mechanism of tunnel lining in a sulfate environment

Sulfate corrosion is one of the main causes of tunnel lining deterioration. An accurate understanding of the damage characteristics and corrosion mechanism of sulfate-corroded tunnels is the basis for the anti-corrosion design and damage control of the tunnel lining. Based on a project concerning a sulfate-corroded tunnel in the mountainous area of Southwest China, this study conducted a field investigation and laboratory tests and, combined with existing research data, summarized the damage characteristics and corrosion mechanism of this type of tunnel and proposed the characteristic corrosion state of tunnel lining in a sulfate environment. The results show that 1) sulfate corrosion led to leakage, surface spalling crystallization, and strength loss, and the corrosion typically occurred at the arch waist and arch foot. 2) Physical and chemical corrosion occurred in the tunnel lining, and the corrosion products included sodium sulfate, calcium carbonate, gypsum, ettringite, and thaumasite. 3) In China, this type of tunnel is mainly located in the Southwest and Northwest, and its lining is in a special state of “one-sided accelerated corrosion.”

Detailed investigation and analysis of the dynamic evolutionary process of rainstorm debris flows in mountain settlements: a case study of Xiangbizui Gully

Short-term heavy rainfall often causes large-scale rainstorm debris flows in mountainous areas of Southwest China. Aiming to investigate the accumulation and movement of potential source material for the formation of debris flow hazards under extreme short-term heavy rainfall, this paper takes the Xiangbizui debris flow gully, Southwest China, as a case study. A detailed field engineering and geological investigation was carried out on the valley characteristics, formation conditions, provenance types, distribution range, loose solid material reserves that can be transformed into debris flows, and characteristics showing the variation in the grain size of the accumulated solids along the gully to further explore the characteristics of rainstorm-induced debris flow movement. The dynamic processes of debris flow movement and accumulation are numerically simulated to analyze the maximum velocity, accumulation height, range of influence, and evolutionary process based on the theory of continuous media of the approximate Voellmy solution and a high-precision three-dimensional model. The results indicated that rainstorms and steep terrain are the main factors stimulating debris flows. The amount of loose solid material in the channel is approximately 1550.61 × 104 m3, and the dynamic material reserves are approximately 396.41 × 104 m3. The maximum flow depth and velocity are approximately 3.5 m/s and 13 m/s, respectively, which mainly occur in the upper and middle reaches of the channel and in the accumulation fan at the outlet of the channel. The evolutionary process of the debris flow includes four stages: a 0–1,500 m initial acceleration stage, a 1,500–2,200 m fast forward movement stage, a 2,200–3,400 m acceleration stage in the middle and lower reaches, and a 3,400–4,300 m deceleration and end of accumulation stage. The research findings can provide a scientific basis and strong support for risk assessment and avoidance, as well as prevention and control of debris flows in mountainous areas with severe climate change.

Modified connection mode of rack system on super-slope bridge under extreme temperature load in rack railway

The construction of rack railways is widely planned across the mountainous areas of Southwest China. However, the huge differences in the daytime and nighttime temperatures in these areas easily lead to deformation mismatch between rack and bridge structures and subsequently result in unpredictable phenomena, such as connection failures in the rack system. This article then explores the vehicle-track (rack)-bridge system (VTRBS) interaction problem caused by extreme temperature loads. Guided by train-track-bridge dynamic interaction theory and considering the meshing behavior of the gear-rack and wheel-rail contact, a dynamic model for investigating the VTRBS interaction under extreme temperature load is constructed. The reliability of the rack system on a super-slope bridge under different rack and sleeper connection modes is studied using this model, and the modified connection mode is proposed. Under an extreme temperature load of –45 ℃, the reliability of the rack system is greatly affected by the rack and sleeper connection modes. When traditional fixed connections are used, the maximum stresses in the rack and fixed connection bolts are 1095 MPa and 1980 MPa, respectively, both exceeding the material strength. When using traditional fasteners, the maximum stresses in the rack and fastener bolts are 203 MPa and 38 MPa, which do not exceed the material strength. However, the elastic displacement between the rack and sleeper exceeds the allowable range of traditional fasteners. When using longitudinal resistance modified fasteners, the stresses in the rack system do not exceed the material strength, but the elastic displacement exceeds the maximum allowable range. When using elastic displacement modified fasteners, the modified elastic displacement ranges between 16 mm and 24 mm, which is within the normal working range. When using longitudinal resistance and elastic displacement modified fasteners, the modified elastic displacement ranges between 12 mm and 24 mm, which is also within the normal working range. These results provide theoretical basis for the early design and later operation and maintenance of rack railways.

Evolution and Transformation Analysis of Land-use in Mountainous “Granary”—Evidence from Typical Basin in Karst Mountainous Areas of Southwest China

Intermountain basins are the granaries of the karst mountains of southwest China. Revealing the process and trend of land-use transformation in typical mountainous “granaries” is of great significance to optimizing land-use, food security, and rural revitalization in the karst mountains of southwest China. Lianjiang basin in Huishui County is the largest in Guizhou Province of southwest China, and a typical mountainous “granary” is used as a case study area. Based on seven periods of high-definition remote sensing images from 1966 to 2020 and on-the-spot investigation, we adopt the analysis methods of landscape pattern, moving window, and buffer zone and conduct an in-depth study on the spatial evolution of land-use and the land-use transformation law of the typical “granaries” of karst mountainous areas in southwest China from the perspectives of changes in the quantity of land-use, changes in the types of land-use, and changes in the landscape pattern. The results showed that the transformation of land-use in the basin was mainly manifested in the transformation of the function of cultivated land and the diversification of the function of cultivated land. The landscape pattern of the basin was gradually transformed from traditional rural landscape to modern agricultural landscape. The gradient effect of land-use evolution and transformation in the study basin was obvious. Traffic, location, and land resources significantly affect land-use transformation in the basin. Based on the above analysis, this paper proposes that the “granary” basins in karst mountainous areas should optimize the land-use of the basin by the trade-off between regional socio-economic development, ecological protection, and food security. The results of this paper provide a reference for land-use optimization and rural development in the granary-type basins and other similar areas in the karst mountains of southwest China.

Analysis on the geographical pattern and driving force of traditional villages based on GIS and Geodetector: a case study of Guizhou, China

Traditional villages have received widespread attention from all walks of life based on important carriers of Chinese rural culture. The mutual superposition of natural and cultural factors may exacerbate the evolution of traditional village geographical patterns. To understand such relationships and effects, factors and degrees influencing traditional villages need to be determined. Here, we analysed the data of 724 traditional villages in Guizhou recognised by relevant national ministries and commissions in China using average nearest neighbour analysis, Tyson polygon analysis, nuclear density analysis and Geodector. The geographic pattern feature revealed that traditional villages, in general, are highly clustered regionally and have significant edge effects on administrative units. Different substrate environments result in significant spatial heterogeneity in village spatial density, clustering, surface undulation, sun exposure, and waterfront. The geographic pattern of traditional villages is mostly affected by the closest distance to river valleys, the types and number of intangible cultural heritage resources in the county, river gorge density, edge effect index, degree of county ethnic language use, and proportion of paddy fields to the regional area; and their combined effects influence and control the community structure. The results highlight the impact of nature and culture on the distribution of traditional villages, which helps traditional village conservation and scientific exploration of human-land relationship issues in the mountainous areas of Southwest China.

From expansion to shrinkage: Exploring the evolution and transition of karst rocky desertification in karst mountainous areas of Southwest China

AbstractSystematic elucidation of the evolution trend of karst rocky desertification (KRD) is of great significance for correctly understanding its occurrence and development process, and implementing effective comprehensive control measures. Based on the existing studies, the authors explore the formation and evolutionary mechanisms and trends of KRD in the karst mountains of Southwest China based on the literature and field investigations. The factors driving the occurrence and formation of KRD are: the single livelihood of farmers in karst mountain areas (KMA); the great land pressure, the low land carrying capacity; and the fragile ecology. With a background of low land carrying capacity, land‐use practices such as over‐cutting, over‐cultivation, and over‐grazing have triggered land degradation in the KMA, including the KRD. With the evolution of social and economic background and the disappearance of its driving factors, the trend of KRD expansion will undergo fundamental change, essentially a KRD transition. KRD transition is the response of the land‐use system to the comprehensive action of economic and social development and ecosystem, which accords with the general trend of economic and social development and ecosystem evolution. The transition of KRD areas outlined in this paper reveals the change of human–land relationship in a KMA in Southwest China and provides a valuable reference for rural revitalization and ecological construction.

Moderate operation scales of agricultural land under the greenhouse and open-field production modes based on DEA model in mountainous areas of southwest China

The identification of the moderate scale of agricultural land was recognized as one of the key measures promoting sustainable agriculture development. However, due to the research gap in mountainous areas, new agricultural business entities (NABE) in these areas usually either refer to the plain area or simply pursue large scale, resulting in low production efficiency and even posing a threat to their sustainable survival. In this study, the Data Envelopment Analysis (DEA) model and Tobit regression model tools were employed to quantitatively reveal the moderate scale and key driving factors of agricultural land under the scale operation modes of greenhouse and open-field types. It was based on 154 NABE questionnaires in the mountainous areas around the Sichuan Basin in China, where NABEs are flourishing. The findings show an approximately "inverted U-shaped" curve relationship between NABE's production efficiency and their planting scale. The primary reason for the failure of NABE to achieve an overall high level of production efficiency is scale inefficiency. The optimal scale intervals for the greenhouse and open-field types of scale operation modes are 3.0–4.3 ha and 3.3–5.0 ha, respectively. Business entities' age, land circulation scale, land rent, and agricultural insurance are common factors that influence the scale efficiencies of both the greenhouse and open-field types. Accordingly, policy interventions regarding the guidance of moderate-scale operation of agricultural land are proposed for achieving the dual goal of cultivating NABE and implementing the Rural Revitalization Strategy in mountainous areas of China. While contributing to the knowledge on scale efficiency of agricultural land, this research also enlightens the practice of policy-making targeted to the sustainable development of agricultural industry led by NABE worldwide.

The occurrence and distributions characteristics of microplastics in soils of different land use patterns in Karst Plateau, Southwest China

Microplastics (MPs) in soils have attracted attention worldwide. However, there are few studies on the abundance and morphological characteristics of MPs under different land use patterns in karst areas. In this work, the distribution characteristics of MPs in soils from five different land use patterns, including industrial mining warehouse (IW), cropland (CL), forest land (FL), grassland (GL), and garden land (GP) in karst mountainous areas of southwest China were investigated. The results suggested that soils in Karst Plateau of Guizhou province under different land use patterns have all been polluted by MPs. The average microplastic abundances of IW, CL, FL, GL, and GP were 3114, 2948, 2770, 2718, and 4200 item kg−1. In the GP and GL soils, foam was the dominant form of MPs (47.53 % and 45.92 %), with pellet MPs accounting for the smallest proportion, while in IW, CL, and FL soils showed the opposite result. The MPs in all soil samples were dominated by small particles (0–0.5 mm), and the main components were PE, PP, PVC, and PET. Meanwhile, the characteristics of MPs in CL soils varied depending on the planted crops. The average abundances of soil microplastics in farmlands planted with corn, pepper, cabbage, watermelon, and other crops were 2504, 2792, 2987, 2370, and 3655 item kg −1. We suggested that land use pattern and crop type may influence karst soil microplastic contamination. The results of this study provide a scientific basis for understanding and controlling the distribution, degradation, and migration of MP pollution in karst regions.

Evaluation of Geological Hazard Risk in Yiliang County, Yunnan Province, Using Combined Assignment Method

Geological disasters are prevalent during urbanization in the mountainous areas of southwest China due to the complex geographic and fragile geologic conditions. This paper relies on the ArcGIS platform as the model operation carrier and takes Yiliang County of Yunnan Province as the research area. Nine evaluation factors such as slope and elevation were selected, and the risk assessment of geological disasters in Yiliang County is carried out by using the combination weighting method. The results show that: (1) the extremely high-risk areas and high-risk areas are distributed in the central, western, and northeastern parts of Yiliang County, of which 164 disaster points are distributed in the area, accounting for 72.56% of the total disaster points; (2) the elevation, human engineering activities, vegetation coverage, and distance from the river are the four main factors affecting the development of geological disasters in the area; (3) the proportions of extremely high-risk areas, high-risk areas, medium-risk areas, and low-risk areas in the total area of the county were 8.08%, 19.61%, 30.59%, and 41.72%, respectively; (4) the verification of the evaluation results by the receiver operating characteristic (ROC) curve shows that the evaluation accuracy is 80%, and the zoning results are consistent with the spatial and temporal distribution of historical disaster points. The combined weighting method can effectively evaluate the risk of geological disasters in Yiliang County, and the results can be used as a scientific reference for local government departments to carry out relevant work.

Interferometric Synthetic Aperture Radar Applicability Analysis for Potential Landslide Identification in Steep Mountainous Areas with C/L Band Data

Landslides frequently occur in the mountainous area of southwest China, resulting in infrastructure damage, as well as a loss of life and property. The use of interferometric synthetic aperture radar (InSAR) technology has become increasingly popular due to its wide coverage, high precision, and efficiency in identifying potential landslides in steep mountainous regions to mitigate risks. This study focused on the Mao County region in China and utilized a small baseline subset of InSAR (SBAS−InSAR) technology with Sentinel-1 and ALOS-2 data to identify the potential landslides and analyze their applicability. To ensure accuracy, the findings were verified using optical image and field surveys. Additionally, a comparative analysis was performed on C-band and L-band SAR data to examine differences in the coherence, geometric distortion, and displacement results, revealing that the L-band has clear advantages in the coherence, suitable observation coverage, and displacement results, while C-band can detect relatively slight displacements. This study aimed to determine the applicability of different SAR satellites for early landslide identification in steep mountainous areas, which can serve as a technical reference for selecting appropriate SAR data and enhancing InSAR identification abilities for potential landslides in the future.

Stability analysis of loose accumulation slopes under rainfall: case study of a high-speed railway in Southwest China

The high and steep slopes along a high-speed railway in the mountainous area of Southwest China are mostly composed of loose accumulations of debris with large internal pores and poor stability, which can easily induce adverse geological disasters under rainfall conditions. To ensure the smooth construction of the high-speed railway and the subsequent safe operation, it is necessary to master the stability evolution process of the loose accumulation slope under rainfall. This article simulates rainfall using the finite element analysis software’s hydromechanical coupling module. The slope stability under various rainfall situations is calculated and analysed based on the strength reduction method. To validate the simulation results, a field monitoring system is established to study the deformation characteristics of the slope under rainfall. The results show that rainfall duration is the key factor affecting slope stability. Given a constant amount of rainfall, the stability of the slope decreases with increasing duration of rainfall. Moreover, when the amount and duration of rainfall are constant, continuous rainfall has a greater impact on slope stability than intermittent rainfall. The setting of the field retaining structures has a significant role in improving slope stability. The field monitoring data show that the slope is in the initial deformation stage and has good stability, which verifies the rationality of the numerical simulation method. The research results can provide some references for understanding the influence of rainfall on the stability of loose accumulation slopes along high-speed railways and establishing a monitoring system.

Estimating Forest Aboveground Biomass Combining Pléiades Satellite Imagery and Field Inventory Data in the Peak–Cluster Karst Region of Southwestern China

The mountainous region of southwest China has the largest karst geomorphology in China and in the world. Quantifying the forest aboveground biomass in this karst region is of great significance for the investigation of carbon storage and carbon cycling in terrestrial ecosystems. In this study, the actual measured aboveground biomass was calculated based on the allometric functions of 106 quadrats from 2012 to 2015. A backpropagation artificial neural network (BPANN) inversion model was constructed by combining very high-resolution satellite imagery, field inventory data, and land use/land cover data to estimate the forest aboveground biomass in the Banzhai watershed, a typical peak–cluster karst basin in southern Guizhou Province. We used 70% of the actual measured aboveground biomass for training the BPANN model, 20% for accuracy verification, and 10% to prevent overtraining. The results show that the absolute root mean square error of the BPANN model was 11.80 t/ha, which accounted for 9.92% of the mean value of aboveground biomass. Based on the BPANN inversion model, the average value of the forests’ aboveground biomass was 135.63 t/ha. The results showed that our study presented a quick, easy, and relatively high-precision method for estimating forest aboveground biomass in the Banzhai watershed. This indicates that the Pléiades image-based BPANN model displayed satisfactory results for estimating the forests’ aboveground biomass in a typical peak–cluster karst basin. This method can be applied to the estimation of forest AGB in the karst mountainous areas of southwest China.

Differences in the distribution, availability, and sorption-desorption isotherms of phosphorus fractions in soil aggregates from cut slopes with different restoration methods

The construction of highways and other transportation facilities resulted in a large number of exposed cut slopes, leading not only to the alteration of soil structure but also to phosphorus (P) losses from soils with low utilization rates. These negative effects can result in stunted plant growth and the occurrence of heavy rainfall and earthquakes-associated landslide and mudslide disasters, threatening people's lives. However, few studies have investigated soil aggregates P in cut slopes restored with different methods in the Alpine Mountainous areas of Southwest China. Therefore, three types of cut slopes (cut slopes restored by three-dimensional mesh (TCS), cut slopes restored by galvanized wire mesh (GCS), and cut slopes restored by nature (NCS)) were selected for the study, and the present study aims to assess the total phosphorus (TP), available phosphorus (AP), and P fractions, as well as the P sorption-desorption isotherms in cut slope soil aggregates. The obtained results are as follows: (1) The TP contents in the soil aggregates did not differ significantly between the three types of cut slopes (p > 0.05), In addition, the AP contents and P activation coefficient (PAC) showed significant differences between TCS, GCS, and NCS, while the H2O-Pi, NaHCO3-Po, NaOH-Pi, NaOH-Po, HHCl-Pi, and HHCl-Po contents were significantly different between the three types of cut slopes (p < 0.05); (2) The AP contents in the three types of cut slopes showed a decreasing trend with increasing soil aggregate size from < 0.25 mm to > 5 mm; (3) H2O-Pi, NaOH-Pi, and HHCl-Pi were the main P fractions affecting the AP contents in the study area, among which NaOH-Pi exhibited the greatest effect on the AP contents; (4) The lowest P adsorption of soil aggregates was observed in NCS. The maximum P adsorption (Qm) values of the < 0.25 mm aggregates in TCS and GCS were higher than those of the other soil aggregate sizes. In addition, the trend of P desorption to increase with P adsorption was more obvious in large aggregates than in small aggregates. The present study provides a theoretical basis for P management in cut slope soils restored by different methods in the Alpine Mountainous region of Southwest China. Moreover, it provides some references for improving cut slope restoration and ecological slope protection techniques.

A catastrophic rainfall-induced high landslide, occurred on December 4, 2020, in the Qingliucun mountainous area of Southwest China

A catastrophic rainfall-induced high landslide, occurred on December 4, 2020, in the Qingliucun mountainous area of Southwest China