Abstract:[Objective] The pollutants distribution during grassland digestion and utilization of rural domestic sewage was explored in order to provide a scientific reference for risk prevention and control in the resource utilization of rural domestic sewage. [Methods] This study investigated the effects of hydraulic load on soil solution and soil pollutant distribution during the grassland digestion and utilization of rural domestic sewage. It also analyzed the variations in soil solution and soil pollutants at different depths and explored the correlation among hydraulic load, soil solution, adn soil pollutants using the Pearson correlation coefficient. [Results] ① As the hydraulic load increased gradually from 0.005 m³/(m²·d) to 0.05 m³/(m²·d), an accumulation of NH⁺₄-N and NO^-₃-N was observed in the grassland. The poor denitrification performance of NO^-₃-N was identified as the limiting step restricting the denitrification rate of the grassland. ② The hydraulic load showed a strong positive correlation with the NH⁺₄-N content in the soil, with a correlation coefficient of 0.94. [Conclusion] During the grassland digestion and utilization of rural domestic sewage, it is necessary to distribute the hydraulic load rationally and control the environmental risks.

Abstract:[Objective] The relationship between the fractal characteristics of soil particle size distribution and properties in different forest types in the typical karst regions of Guangxi Zhuang Autonomous Region (GZAR) was investigated in order to provide scientific guidance for sustainable forestry development in rocky desertification areas. [Methods] The particle size distribution and properties of soil in Eucalyptus spp., Pinus massoniana, and natural secondary forests were determined. Single and multiple fractal dimensions of soil from different forest types were calculated using fractal models, and the their correlations with soil properties were explored. [Results] Compared to natural secondary forests, the bulk densities of Eucalyptus spp. and P. massoniana plantations were 23% and 15% lesser, respectively. However, the total porosities of Eucalyptus spp. and P. massoniana plantations were greater by 27% and 17%, respectively, than that of natural secondary forests. The clay contents in Eucalyptus spp. and P. massoniana plantations were lower(58% and 42%, respectively) whereas the sand contents were higher (24% and 14%, respectively), than that of natural secondary forests. Additionally, the single fractal dimensions (D_s) were 6% and 4% lesser in Eucalyptus spp. and P. massoniana plantations, respectively, than that of secondary natural forests. Furthermore, the available phosphorus, readily available potassium, and total calcium contents for Eucalyptus spp. were 68%, 49%, and 6% lower, and, those for P. massoniana were 42%, 40%, and 25% lower, respectively, than those of secondary natural forests. D₀-D₂, ΔD and Δα were the multifractal parameters that reflect the heterogeneity of soil particle size distribution across different dimensions; for Eucalyptus spp. (0.13, 1.29, 1.52) and P. massoniana (0.13, 0.99, 1.18) plantations these values were higher than those for natural forests (0.08, 0.83, 1.02). Furthermore, there was a significant correlation between multifractal parameters and soil nutrient content in the different plantations. [Conclusion] Improper cultivation and management of plantations in karst regions may promote the loss of fine soil particles and depletion of key nutrients. This, in turn, can result in a concentration of the soil particle size distribution in low-probability dense areas, increasing the heterogeneity of the soil particle size distribution and further accelerating the process of rocky desertification. The single fractal dimension D_s can reflect the degree of soil fertility degradation in karst forest areas, and the multifractal parameters can reveal the heterogeneous distribution characteristics of soil particle size at the microlevel in detail. Therefore, single and multiple fractal dimensions have the potential to become precise indicators for evaluating the soil quality of plantations in karst regions.

Abstract:[Objective] The effect of combining organic fertilizer with a water retaining agent on the hydraulic properties of brown soil in the tillage layer was analyzed in order to provide a technical approach and theoretical basis that can be used to improve brown soil tillage by finding the optimal organic fertilizer application amount and the optimal water retaining agent ratio. [Methods] A brown soil topsoil from Shanxi Province and a split-plot experimental design were used for the experiment. The main plot treatments were the amount of organic fertilizer applied: F₁ (0 t/hm²), F₂ (45 t/hm²), F₃ (60 t/hm²), and F₄ (75 t/hm²), and the subplot treatments were four water-retaining agent applications: B₁ (0 kg/hm²), B₂ (300 kg/hm²), B₃ (600 kg/hm²), and B₄ (900 kg/hm²). The effects of the amount of organic fertilizer and water-retaining agent on the soil water characteristics curve, specific water capacity, and available water content were analyzed. [Results] ① Soil water-holding capacity, water-supply capacity, and the effective water content increased in the organic fertilizer combined with water-retaining agent treatments compared to the water-retaining agent alone treatments. ② The effects of organic fertilizer combined with a water-retaining agent on soil hydraulic properties varied depending on the amounts of organic fertilizer applied. The water-holding capacity and water-supplying capacity of the test soil at low suction section followed the order F₃ > F₂ > F₄ > F₁, and the same was true for the effective water content. ③ Under the F₃ treatment, the water holding capacity and water supply capacity of the soil first increased and then decreased as the water retaining agent application rate increased. There was a parabolic relationship between the effective soil water content and water-retaining agent application ratio (R²=0.949 3). [Conclusion] The improvement effect was greatest under the treatments with a medium amount of organic fertilizer (60 t/hm²) combined with a water-retaining agent and the optimum proportion of water-retaining agent under this amount of organic fertilizer was 0.91%.

Abstract:[Objective] The hydrodynamic properties of red soil slopes under varying surface roughness, slope, and flow rate were analyzed in order to provide scientific basis for a better understanding and prediction of sheet erosion on red soil slopes. [Methods] A study was conducted to simulate red soil slopes with varying surface roughness by using different particle sizes (0.25—1, 1—3, 3—5, 5—7, and 7—10 mm). The experiments involved four flow rates (2, 4, 8, and 16 L/min) and four slopes (5°, 10°, 15°, and 20°). Photogrammetry based on the structure from the motion technique and the electrolyte tracing method were used to determine the surface roughness and flow velocity on the slope. The collected data were used to calculate the surface roughness and hydrodynamic parameters under each condition. [Results] The mean flow velocity varied from 0.022 to 0.531 m/s under the experimental design conditions. The Reynolds numbers ranged from 63 to 1 155, Froude numbers ranged from 0.1 to 4.1, and the resistance coefficients were within the range of 0.13 to 68.86. The surface roughness was positively correlated with the resistance coefficient (p<0.01) and negatively correlated with the Reynolds number (p<0.05), Froude number, and flow velocity (p<0.01). The slope was positively correlated with the unit-width discharge of overland flow and the Froude number (p<0.01). The width discharge was positively correlated with the Reynolds number, Froude number, and average flow velocity (p<0.01) and negatively correlated with the resistance coefficient (p<0.01). [Conclusion] Increased surface roughness augments the resistance to overland flow and reduces the influence of flow inertia, serving as a crucial factor in determining the mean flow velocity, Froude number, and resistance coefficient. The unit-width discharge primarily influences the Reynolds number by altering the water depth and flow inertia of the overland flow. Compared with the surface roughness and unit-width discharge, the slope had the least impact on the mean flow velocity, Reynolds number, Froude number, and resistance coefficient. The relationship of the mean flow velocity and Froude number with the surface roughness, unit-width discharge, and slope can be described well by the power function. Similarly, the Reynolds number and resistance coefficient exhibited a strong power function relationship with the unit width discharge and surface roughness.

Abstract:[Objective] The regulatory effectiveness of S-shaped vegetation dams with varying flow path width ratios on debris flows were analyzed to explore the role of bioengineering measures in energy dissipation and disaster mitigation, in order to provide a theoretical foundation for constructing an eco-geotechnical synergistic disaster mitigation model. [Methods] Flume experiments were conducted on vegetation dams with S-shaped flow paths and width ratios of 0% (S₀), 30% (S₃₀), 45% (S₄₅), 60% (S₆₀), and 75% (S₇₅). These tests focused on the flow velocity regulation, flow volume regulation, sediment control, and energy dissipation. [Results] ① The vegetation dam with a 0% flow path width ratio (S₀) exhibited impressive debris flow interception capabilities, reducing 31.03%—44.19% of the flow velocity, 45.88%—56.02% of the flow volume, 34.37%—52.72% of energy dissipation levels, meanwhile, it also achieved an increase in sediment interception rate of 3.31%—75.69%. ② The vegetation dam with a 75% flow path width ratio (S₇₅) showed strong sediment discharge capabilities, reducing 7.69%—29.03% of flow velocity, and 2.94%—35.54% of flow volume, and 11.56%—34.09% of energy dissipation levels, meanwhile, it also achieved and increase in sediment interception rafe of 4.13%—45.69%. ③ The vegetation dam with a 45% flow path width ratio (S₄₅) demonstrated a balanced performance in interception and discharge compared to S₃₀ and S₆₀. It reduced 11.11%—40.00%, 16.47%—51.20%, 1.63%—54.75% of flow velocity, flow volume, and energy dissipation, respectively. The interception rate of the plant dam reached 18.04%—45.16%. [Conclusion] An S-shaped vegetation dam with a 0% flow path width ratio (S₀) is ideal for debris-flow channels focused on interception. In contrast, a width ratio of 75%(S₇₅) was better suited for channels that prioritize sediment discharge. The 45% width ratio (S₄₅) effectively balances the interception and discharge.

Abstract:[Objective] The runoff distribution and soil-water conservation benefits of slope croplands with different planting patterns in dry-hot valleys were analyzed in order to provide a scientific basis for the construction of soil and water conservation orchards in the Jinsha River dry-hot valley. [Methods] An in-situ runoff plot monitoring was used, and two typical planting patterns of fruit trees in dry-hot valley slope cropland were selected for the study: monoculture (grapes, dates, and stylosanthes) and fruit-grass intercropping (grapes+stylosanthes, dates+stylosanthes); the bare land was used as a control. The differences in surface runoff, subsurface flow, and soil erosion between different crops and planting patterns were compared to explore the runoff allocation mechanism and evaluate the soil and water conservation benefits on different planting patterns. [Results] Surface runoff was dominant in dry-hot valleys under different cropping patterns, and bare land runoff(53.2%—94.07%), rainfall amount, rainfall intensity, and vegetation coverage were the key factors affecting soil erosion in the dry-hot valley slope cropland. Different planting patterns regulated the distribution of runoff in the deep soil layers to significantly reduce surface runoff (50.79%—89.70%) and sediment runoff (54.66%—77.13%). The 50 cm and 100 cm interflows of the fruit-grass intercropping pattern were higher than those of the other patterns. The runoff reduction (78.53%, 72.54%) and sediment reduction (71.76%, 63.21%) benefits of the fruit-grass intercropping pattern (dates+stylosanthes, grapes+stylosanthes) were significantly higher than those of the monoculture pattern. [Conclusion] The fruit-grass composite intercropping system redistributes rainfall runoff by directing surface runoff into deep soil, thus providing better benefits for soil and water conservation.

Abstract:[Objective] The characteristics and processes of soil nutrient loss in the platform slope system of a discharge site in China’s mining area were analyzed in order to provide a theoretical basis for preventing and controlling nutrient loss at discharge sites. [Methods] Using the discharge site of the Haizhou open-pit coal mine in Fuxin City, Liaoning Province, as the research object, an indoor model of the platform-slope system of the discharge site was established through the principle of a similar simulation, and an artificial rainfall simulation test was used to study the process and characteristics of nutrient loss from the platform-slope system of the discharge site under different rainfall intensities (60, 90, and 120 mm/h). [Results] ① With escalating rainfall intensity, the soil nutrient concentrations for nitrogen, phosphorus, and potassium in the dump waste platform-slope system exhibited a pattern of initial decline, subsequent rise, and then a gradual decrease, 60 mm/h ＞ 90 mm/h ＞ 120 mm/h for each intensity. ② The runoff nutrient loss from the platform slope soil increased with increasing rainfall intensity, notably for total nitrogen (TN), total phosphorus (TP), and total potassium (TK). However, the loss of nitrate (NO^-₃-N), ammonium (NH⁺₄-N), available phosphorus (AP), and available potassium (AK) in runoff did not change significantly with increasing rainfall intensity. ③ The nutrient concentration in the soil sediment from the dump waste platform slope consistently exceeded that found in surface runoff, with sediment nutrient loss escalating as the rainfall intensity increased. ④ The enrichment ratio of total nitrogen and total potassium in soil sediment rose with greater rainfall intensity, expressed as TN ＞ TP＞ TK. [Conclusion] The concentration of soil nutrients lost in the dump waste platform-slope system was predominantly influenced by rainfall intensity and soil characteristics.

Abstract:[Objective] The use of modified hydrophilic polyurethane resin binder (W-OH) solution at different concentrations to reduce leakage from gravel slag slopes was investigated to provide theoretical support for reducing leakages from coarse gravel slag and to improve vegetation restoration in rocky desertification areas. [Methods] A highway slag slope in the rocky desertification area of the Guangxi Zhuang Autonomous Region was investigated. Artificial erosion experiments were conducted on a sloping gravel surface and the treatments were different concentrations of added W-OH solution with different erosion flow rates. [Results] The slope that was not treated with the W-OH solution produced large amounts of leakage water and runoff on the slope only appeared when the scouring discharge was greater than 30 L/min. When the scouring discharge was 30 L/min, the runoff rate accounted for 18.3% of the incoming flow rate and 81.7% of the water was lost due to slope leakage. However, the average runoff and average infiltration rates for the slope after treatment with the W-OH solution increased as the inflow rate and W-OH solution concentration rose. The stable runoff rate for the slope treated with W-OH solution concentrations of 3%—6% increased by 200%—385.5% compared to that of the untreated slopes and the higher the concentration of the W-OH solution, the better the treatment effect on the slope. The infiltration runoff ratio decreased as the inflow rate and the W-OH solution concentration increased. [Conclusion] Treatment with the W-OH solution effectively reduced leakage from coarse-grained slag slopes and improved the water retention capacity of the slope. These improvements contributed to slope vegetation restoration.

Abstract:[Objective] The variation patterns of C, N, and P contents in soil and their ecological stoichiometric characteristics during the process of vegetation restoration in arid zones was analysed in order to provide a scientific basis for accurately assessing the impacts of sand-fixing vegetation on soil nutrients in arid environments. [Methods] A Hedysarum scoparium community in the 1992 aerial seeding afforestation area at the northeastern edge of the Tengger Desert was taken as the research object. The native vegetation Artemisia oleifera as well as a quicksand land without vegetation restoration measures were used as the control (CK). The soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) levels across a soil profile in the H. scoparium community and their eco-chemometric characteristics were analyzed. [Results] ① The SOC, TN, and TP contents of the soil from the H. scoparium community, which was established more than 30 years ago, were 0.71, 0.03, and 0.27 g/kg, respectively. These were all significantly higher than those of the unseeded quicksand land by 73.2%, 50%, and 145.5%, respectively. The SOC was restored to 58.6% of that of the native vegetation A. oleifera. The distributions of SOC, TN, and TP content in the H. scoparium soil decreased with soil depth and were significantly higher in the 0—10 cm soil layer than in the other soil layers (p<0.05). ② The soil C∶P and N∶P ratios of the H. scoparium community were 0.57, and 0.13, which were 30.5% and 48% lower than those of the bare sand, respectively. The C∶N ratio was 22.41, which was 73.2% higher than that of the bare sand. The soil C∶P and N∶P ratios decreased with increasing soil depth, whereas the C∶N ratio showed an increasing followed by a decreasing trend. The average N∶P ratio in the H. scoparium community at a soil depth of 0—200 cm was 0.13, which was much smaller than 14 in the control groups. [Conclusion] The accumulation of soil nutrients in the study area became evident as sand-fixing vegetation was restored. The growth of the H. scoparium community was mainly limited by N. Thus, it is recommended to apply increased amounts of N fertilizer in the later stages of the H. scoparium community establishment. In addition, the H. scoparium community was observed to have a low soil organic matter mineralization rate, a lower rate of SOC decomposition than SOC accumulation, and a favorable soil environment for C accumulation.

Abstract:[Objective] The temporal and spatial variation of understory vegetation coverage and its driving factors in Hubei Province were studied to provide scientific basis for ecological environment protection and vegetation management in this area. [Methods] Hubei Province was selected as the study area, and understory green leaf vegetation cover and understory litter cover were extracted from 28 sample plots for every half month in 2022 through field survey and DeepLabV3⁺ semantic segmentation method. Based on this, various machine learning models were used to analyze the impact of four driving factors, namely spatial location, natural environment, social and economic environment, and climate conditions, on changes in understory green leaf vegetation cover. [Results] Monthly variations in understory litter cover did not show obvious seasonal characteristics, and there was considerable spatial and temporal heterogeneity in the understory litter cover among the sample plots. In contrast, understory green leaf vegetation cover showed obvious seasonal change characteristics, and there were significant differences in understory green leaf vegetation cover among different vegetation types; the understory green leaf vegetation cover of economic forests and conifers was generally higher than that of broadleaf deciduous forests and evergreen broadleaf forests, and the differences in understory green leaf vegetation cover between broadleaf deciduous and evergreen broadleaf forests were relatively small. The random forest regression model showed the best prediction performance, with a root mean square error (RMSE) of 11.072 3 and a coefficient of determination (R²) of 0.732. [Conclusion] The random forest regression model showed that temperature, NDVI, and precipitation in the previous month were the key driving factors for spatiotemporal changes in the understory green leaf vegetation cover.

Abstract:[Objective] The plant composition of typical catchment area of the Loess Plateau was analyzed to evaluate its ecological restoration status and provide scientific guidance for further implementation of vegetation restoration measures to improve the effectiveness of soil and water conservation. [Methods] Based on the Heshui (HS) and Jingbian (JB) landslide-dammed reservoir catchments located in the plateau-gully region of the southern central area and the hill-gully region of the northern central area of the Loess Plateau, respectively, comprehensive surveys were conducted to document the existing vegetation types, identify the pollen composition in the topsoil, and analyze the physical properties of the topsoil, including water content, grain size, and loss on ignition at 550 ℃. [Results] In total, 230 genera from 84 families were identified in the HS catchment, and 223 genera from 78 families were identified in the JB catchment. Nevertheless, there was a higher abundance of woody plants, moisture-loving grasses, and herbs around the HS catchment (51.74%), whereas xerophytic shrubs and herbs dominated around the JB catchment (56.50%). These patterns reflected a combination of climatic conditions, soil properties, land use conditions, and agricultural and economic development. In addition, the current high vegetation coverage area under the 'Grain for Green’ project accounted for 82.61% and 37.80% of the area around the HS and JB catchments, respectively. However, certain adverse phenomena, including invasive non-native plant species, a low proportion of indigenous flora, and a noticeable presence of artificial plants, have been observed. [Conclusion] To ensure sustainable vegetation regeneration, ecological restoration of small catchments in the Loess Plateau should fully consider the local climate and plant characteristics.

Abstract:[Objective] The spatiotemporal evolution characteristics and attributes of land desertification in the middle and upper reaches of Yarlung Zangbo River were analyzed and identified to provide scientific support for ecological restoration and protection and promote a virtuous cycle of the ecosystem in this region. [Methods] An improved desertification difference index method based on the three-dimensional space of vegetation, surface reflectance, and soil moisture (NDVI-Albedo-Wet) were employed to analyze the spatiotemporal evolution of land desertification in the research area during 1990—2020. On this basis, attribute analysis of land desertification was conducted from the perspectives of temporal changes and spatial differentiation using principal component analysis and geographical detector methods, respectively. [Results] The total area of land desertification decreased from 3.48×10⁴ km² in 1990 to 1.67×10⁴ km² in 2020; however, the degree of land desertification increased in certain areas, particularly in the western part of the study area, such as Saga and Jilong, and the southeastern parts, such as Kangma and Qiongjie County. The spatial distribution of land desertification exhibited a strip-like pattern along the main river channel from west to east, being concentrated on gentle slopes, moderate slopes, grasslands, and unused land. During 1990—2020, the reversal of land desertification in the study area was primarily influenced by human activities, with the principal contributing factors accounting for 59.1% of the total reversal. The spatial differentiation of land desertification shifted from dependence on natural geographical factors, such as elevation and wind speed, in 1990, to the synergistic influence of multiple factors, including natural and socioeconomic factors, in 2020, with the impact of various driving factors on the spatial distribution of land desertification exhibiting dual-factor enhancement and non-linear increase. [Conclusion] The degree of land desertification in the middle and upper reaches of the Yarlung Zangbo River basin was alleviated between 1988 and 2020; however, local exacerbations persisted. Hence, further strengthening the ecological restoration of the source area and enhancing sand source management and vegetation cultivation within a 10 km radius of both the left and right banks of the river is necessary.

Abstract:[Objective] The soil and water conservation benefits and the economic benefits of crop increments in terrace reclamation projects at the small watershed scale in the hilly areas of Southern China were evaluated and optimized, and the trade-off relationship between the conservation benefits and the economic benefits was analyzed in order to provide scientific guidance for the formulation of a spatial optimization layout for the Danjiangkou City, Hubei Province. [Methods] Remote sensing and spatial analysis techniques were used to identify the spatial distribution of terraces in Danjiangkou City and delineate the small watersheds. The Chinese Soil Loss Equation (CSLE) model was combined with field investigations to evaluate the trade-off between soil and water conservation benefits and crop value added when slope cropland was converted to terrace cropland. A linear optimization method was used to determine the optimal spatial layout of the project under multiple scenarios. [Results] The terraces and slope croplands in Danjiangkou City were mainly distributed in the central and northern watersheds and they exhibited higher total benefits in terms of soil and water conservation and value-added economic benefits. The spatial optimization analysis of each small watershed indicated that under the soil and water conservation priority scenario, the changing slope cropland to terrace land project areas were primarily concentrated in the southwestern watershed, whereas under the crop value-added economic benefits priority scenario, the project areas were more heavily concentrated in the central watershed. The linear optimization results under the different scenarios showed a significant trade-off between the soil and water conservation priority and the crop value-added economic benefits priority. Under the different scenarios, the maximum soil and water conservation benefit was an approximately 3.21×10⁶ t reduction in erosion with crop value-added economic benefits of approximately 1.78×10⁸ yuan. The maximum crop value-added economic benefit result was approximately 1.87×10⁸ yuan with soil and water conservation benefits reduced to approximately 3.01×10⁶ t. The Pareto optimal solutions reflected the tradeoff between the two. [Conclusion] The spatial optimization methods used in this study quantified and optimized the trade-off relationship between water conservation benefits and the crop value-added economic benefits in projects where sloping land was converted to terrace land. The results provide a series of non-dominated solutions that can be used to aid government decision-making processes.

Abstract:[Objective] A comprehensive risk assessment system for collapses and landslides in the karst regions of the Guangxi Zhuang Autonomous Region was established, in order to offerscientific support for early warning, disaster prevention, and mitigation in the area. [Methods] Beiliu City was selected as the study area, and a database of collapses and landslides was constructed. Slope units were used as the basis for the evaluation, with multisource data systematically collected and analyzed. Key evaluation indicators, including groundwater type and runoff intensity index, were identified, and a fully connected neural network model was employed to assess the susceptibility to collapses and landslides. Given the region’s vulnerability to rainfall and karst erosion, the soil erosion modulus was incorporated into the hazard assessment. Finally, a risk evaluation model for collapses and landslides in Beiliu City was developed by integrating vulnerability assessments of the exposed elements. [Results] The findings revealed that high- and very high-risk zones covered 252.22 km², accounting for 10.27% of Beiliu City’s total area. These zones are primarily located in Longsheng Town, Xinfeng Town, Pingzheng Town, and Liujing Town, which are characterized by eroded and denuded hills and tectonic erosion of low mountains. Factors such as loose geotechnical body, high soil erosion modulus, dense population, and concentrated buildings significantly heightened the collapse and landslide risks, resulting in a high-risk classification. [Conclusion] Validation through ROC curves and field investigations showed an accuracy of 0.966 4 for susceptibility evaluation and 89.3% for risk assessment in Beiliu City. These results demonstrate the high precision and practical applicability of the constructed model, which aligns closely with real-world scenarios.

Abstract:[Objective] The key ecological corridors, ecological nodes, and obstacle points in the Hainan Zang Autonomous Prefecture, Qinghai Province was identified, and the ecological security pattern of the Hainan Prefecture was described in order to provide a reference for its ecological environmental protection and sustainable development. [Methods] The ecological security pattern of the Hainan Prefecture was described using the InVEST model and circuit theory method based on the source-resistance surface-corridor framework. The Hainan Zang Autonomous Prefecture (Hainan Prefecture) in the Qinghai Province, an important water conservation area at the headwaters of the Yellow River, was the research object. [Results] ① Ecosystem services in the Hainan Prefecture were generally good and mainly included very important and highly important services. ② The ecological source area in this study was approximately 5 463 km², accounting for 12.0% of the total study area. Scattered patches were mainly distributed in the south and east of the Hainan Prefecture and at the southern bank of the Qinghai Lake. A total of 55 ecological corridors were identified, with a total length of 1 963 km, including 22 key corridors, with a dense distribution pattern in the south and east and sparse distribution in the west. A total of 37 ecological pinch points and 32 ecological obstacle points were identified, which were mainly distributed in the central parts of Gonghe and Guide County. ③ The ecological source, corridor, pinch point, and obstacle point areas were combined to form an ecological security pattern. [Conclusion] Future endeavors should focus on the protection and restoration of habitats in the western part of the study area, strengthening the service capacity of the ecological source area at the southern, eastern, and southern banks of the Qinghai Lake to improve the overall connectivity of the ecosystem in the Hainan Prefecture.

Abstract:[Objective] The characteristics and causal mechanisms of low-frequency debris flows in the Qinling Mountains was analyzed in order to provide a scientific reference for their prevention and mitigation. [Methods] The “8·11” Jiwozi flash flood and debris flow of 2023 served as the research subject. Using field investigations and numerical simulations, actual precipitation frequencies were used to reverse engineer the formation process of the flash flood and debris flow, and a risk assessment was carried out. [Results] ① Intense rainfall accumulated quickly, forming torrents that erode loose materials in upstream channels. This process, known as the “fire hose” effect, triggered mountain floods and debris flows. Assisted by steep terrain, these flows eroded channels across the watershed, and a significant amount of sediment spreads downstream, forming alluvial fans and blocking river channels. ② Simulations under actual rainfall frequencies showed that the sediment deposition depths across the watershed ranges from 0.04 to 5.63 meters, with a maximum flow velocity of 7.43 m/s. The area of the alluvial fan was 1.91×10⁴ m², and the one-time discharge volume was 78 271 m³. ③ Based on flow velocity, sediment depth, and hazard range, three danger zones were identified (high, medium, and low). The area on the western side of the alluvial fan, with higher elevation, was classified as a low-risk zone, accounting for approximately 10% of the fan area. The central area and the area from the edge of the fan to the road were classified as medium-risk zones, comprising 62% of the total area. The southeastern and southwestern areas of the alluvial fan were high-risk zones, accounting for 28% of the area. [Conclusion] The “8·11” Jiwozi flash flood and debris flow in 2023 was a typical low-frequency flash flood and debris flow disaster triggered by extreme short-duration heavy rainfall. The FLO-2D model effectively simulates the movement and deposition processes of the debris flow and determines the hazardous areas.

Abstract:[Objective] The distribution characteristics of Benggang in Shangyou County, Jiangxi Province was analyzed, and its risk was evaluated, so as to provide data support and scientific basis for priority decision-making of Benggang governance. [Methods] Shangyou County, Jiangxi Province was taken as the research area. Based on the comprehensive investigation of Benggang and its hazard characteristics, according to the principle of three elements of Benggang risk, the scale and development status of Benggang were selected as the main risk potential indicators of the main body of Benggang. Hazard receptors such as houses, roads, and farmland were selected and combined with the hazard distance as the hazard degree index. The risk evaluation index system of Benggang based on the matrix discriminant method was constructed to explore the accuracy of this method in evaluating the Benggang risk. [Results] ① There were 227 Benggang in Shangyou County, of which 25 had been controlled and 202 had not been controlled. The type of development status was mostly active, scale was mostly large, morphological type was mainly dipper, hazard object was mainly farmland, and hazard distance was mainly less than 10 m. ② In Shangyou County, the proportions of the five risk levels of no, small, medium, large, and great to the number of Benggang was 47.5%,14.9%,15.8%,14.9% and 6.9%, respectively, and the accuracy of on-site verification reached 80%. ③ The Benggang of large and extremely dangerous levels in Shangyou County was mainly distributed in Yingqian Town and Shuiyan Township, and a small part was located in Meishui Township and Huangbu Town, which needs priority treatment. [Conclusion] The matrix discriminant method proposed in this study is accurate and the indicators are easy to obtain. The method is easy to operate and is applicable to the evaluation of the risk of Benggang.

Abstract:[Objective] The effective soil thickness of a region was rapidly and accurately obtained, and its spatial distribution and influencing factors was analyzed, in order to provide theoretical guidance for vegetation growth, soil conservation, and food security. [Methods] Taking the Xinanjiang River basin as the research area, combining field survey data, topography, lithology, climate, and other soil-forming factors, the empirical Bayesian Kriging regression prediction (EBKRP) and random forest (RF) algorithms were applied to obtain the effective soil thickness inversion results. The relationship between this data and environmental variables was also analyzed. [Results] ① The average effective soil thickness in the region ranged from 0.2 to 0.3 m. Soil thickness was higher in basin and plain areas with concentrated urban development and intensive human activity. Meanwhile, it was lower in hilly and mountainous regions. ② Based on three accuracy evaluation indicators of MAE (mean absolute error), R² (coefficient of determination), and RMSE (root mean square error), the prediction results of the RF algorithm were significantly better than those of the EBKRP algorithm. It could more effectively show the spatial heterogeneity distribution of soil thickness, improving the effect of soil thickness digital mapping. ③ The effective soil thickness estimation was strongly influenced by topography and climate variables, which accounted for 46.77% and 18.78% of the variable importance, respectively. [Conclusion] The RF algorithm could effectively invert regional effective soil thickness, overcoming the spatial heterogeneity of soil thickness, and is more accurate and has a higher resolution compared to models with limited sampling.

Abstract:[Objective] The evolution process of land use conflict and its formation and change mechanisms were explored to promote the alleviation of regional land-use conflict and optimize the allocation of regional land resources. [Methods] Based on a spatiotemporal dynamic process, a model for identifying land-use conflicts developed from a landscape pattern perspective was applied to diagnose land-use conflict situations across five periods (2000, 2005, 2010, 2015, and 2020) in Wuhu City, Anhui Province. By integrating the Bayesian hierarchical spatiotemporal model and the optimal parameter-based geographical detector, a framework was established to understand the formation mechanisms of the spatiotemporal dynamics of land-use conflicts, identifying the spatiotemporal dynamics and driving forces of land use conflicts in Wuhu City. The PLUS model was applied to conduct multi-scenario simulations and conflict mitigation analyses for land use in Wuhu City in 2030. [Results] ① Over the study period, the level of land-use conflicts in Wuhu City fluctuated upward, with the spatial pattern predominantly displaying a higher conflict density in the south and lower in the north, continuously expanding along the Changjiang River axis. Hotspots of local variation were concentrated in the urban-rural fringe areas, where agricultural and ecological spaces intersected. ② Land-use conflict patterns in Wuhu City were primarily formed by factors such as elevation, slope, proximity to roads, and distance from water systems, while GDP and population distribution had less influence on land-use conflict formation. ③ The pattern of land-use conflicts was expected to persist under different scenarios; notably, scenarios focused on farmland conservation and ecological protection could effectively mitigate the emergence of land-use conflicts, and the balance between agriculture, ecology and economic development should be maintained in the management process. [Conclusion] Land-use conflict in Wuhu City is constantly strengthening with the impact of deepening social development. In the future, it is still necessary to strengthen the control of land use according to local conditions, improve the level of land use conservation and intensive, and achieve high-quality development.

Abstract:[Objective] The soil water evaporation characteristics of soil cracks after different backfilling techniques was analyzed in order to provide scientific basis for the effective control of soil cracks in the dump hence promote ecological environment restoration and land reclamation. [Methods] The soil was collected from the surface of the west dump of Haizhou open-pit mine and the soil cracks were simulated by backfilling treatment and analyzed by the simulated evaporation test in the laboratory. [Results] The daily evaporation of cracks showed an obvious three-stage evaporation rule, and different backfilling treatments had little effect on the daily evaporation of cracks. With the increase of crack width, the cumulative evaporation of cracks increased and backfill treatment effectively reduced the cumulative evaporation of cracks. The cumulative evaporation of cracks with a backfilling ratio of 1∶1 (treatment 1) was the minimum value under the same group of cracks backfilling. The appearance of cracks would lead to the reduction of soil moisture content, but backfill treatment could improve the moisture content of cracks, and the water content of backfilling ratio of 1∶1 (treatment 1) was the highest value of the three groups of cracks, with an average value of 29.74%. The increase of crack width also had an impact on the evaporative water-loss ratio and the backfill treatment could reduce the evaporative water-loss ratio. The backfill ratio of 1∶1 (treatment 1) had the best performance in reducing the evaporative water-loss ratio. [Conclusion] The existence of cracks has an effect on the daily evaporation, cumulative evaporation, water content, and evaporation water loss ratio of cracks, and the 1∶1 backfill ratio (treatment 1) has the best performance in the study of water evaporation of soil cracks in the dump.

Abstract:[Objective] Vegetation restoration and screening with suitable trees and grasses in power transmission projects were performed to provide scientific guidance to improve vegetation restoration success in power transmission and transformation projects, reduce soil erosion caused by the project, and reduce ecological restoration costs. This is particularly important to guarantee the green, high-quality and sustainable development of power grids. [Methods] Using on-site investigation, field observation, and indoor analysis, 26 planting observation points were set up to observe the growth of grass and tree taxa two and five years after planting. The observation indices mainly included grass taxa and their height, hay production, tree taxa and their height, branch number, and crown width. The entropy value method was used to sort and screen the suitability of the growth of the grass and tree taxa in the various vegetation sub-zones along the transmission and substation routes. [Results] According to the observations, six grass taxa (Agropyron ristatum, Achnathurum splendens, Melilotus suavcolen, Medicago sativa, Elymus sibiricus and Elymus dahuricus) and six tree taxa (Tamarix hohenackeri, Caragana korshinskii, Hippophae rhamnoides, Haloxylon aphyllum, Sabina vulgaris, and Populus euphratica) were screened for the suitability evaluation. The results showed that in the broadleaf-deciduous mixed zone of the Qinling Mountains, A. splendens, M. sativa, and C. korshinskii ranked No. 1. In the desert Gobi zone of the West Hebei Corridor, M. suavcolen (No. 2) and H. aphyllum (No. 1) ranked the highest. In the oasis plain zone of the Hexi Corridor, A. ristatum (No. 2) and H. rhamnoides subsp. sinensis (No. 1) ranked the highest. In the desert grassland zone of the Hexi Corridor, E. sibiricus (No. 2), T. hohenackeri (No. 1) and P. euphratica (No. 1) ranked the highest. In the desert steppe zone of the Loess Plateau, E. dahuricus, T. hohenacke, C. korshinskii, H. aphyllum, and S. vulgaris were the most highly ranked species, and they were all ranked No. 2. In the dry steppe zone of the Loess Plateau, A. splendens (No. 2) and S. vulgaris ranked No. 1. [Conclusion] Selecting suitable tree and grass taxa for vegetation restoration in each vegetation zone along the transmission line should be adapted to local conditions, taking into account the suitability for growth and ecological function. It is recommended to prioritize selecting native species. For example, in the dry grassland area of the Loess Plateau, it is preferable to prioritize planting water with A. splendens, H. rhamnoides and S. vulgaris.

Abstract:[Objective] The effect of afforestation on soil organic carbon density (SOCD) was studied to provide a scientific basis for improving the carbon sink of terrestrial ecosystems in the forest-steppe ecotone of Northern Hebei Province. [Methods] Scotch pines (Pinus Sylvestris var. mongolica) and larch (Larix principis-rupprechtii) plantations were selected as the research subjects in the Yudaokou area located in a forest-steppe ecotone. Unforested lands (including unforested land Ⅰ with high biomass, unforested land Ⅱ with medium biomass, and unforested land Ⅲ with low biomass) served as controls. The soil organic carbon (SOC ) content and soil organic carbon density (SOCD) of different terrestrial ecosystems were studied. [Results] ① The SOC content of unforested lands in Yudaokou area ranging from 2.54 to 60.57 g/kg were positively correlated with the vegetation biomass. ② At the same age (16—20 years), the SOC content in the L. principis-rupprechtii and P. Sylvestris var. mongolica plantations was significantly higher than that in unforested land Ⅱ and unforested land Ⅲ and lower than that in unforested land Ⅰ (p<0.05), and the SOC content in the L. principis-rupprechtii plantations was higher than that in the P. Sylvestris var. mongolica plantations, with a significant difference observed in the 0—10 cm soil layer (p<0.05). ③ The order of SOCD (0—60 cm) from high to low was unforested land Ⅰ (127.56 t/hm²)＞L. principis-rupprechtii plantation(105.26 t/hm²)＞P. Sylvestris var. mongolica plantation (75.52 t/hm²)＞ unforested land Ⅱ (56.06 t/hm²)＞ unforested land Ⅲ (31.78 t/hm²), and there were significant differences between the vegetation types (p＜0.05) except that between P. Sylvestris var. mongolica plantations and unforested land Ⅱ (p>0.05). ④ The SOCD of 0—60 cm in the L. principis-rupprechtii plantations increased with the increase of the ages in all soil layer, and they were 105.26 t/hm² (16~20 a), 112.29 t/hm²(21~25 a) and 159.73 t/hm² (26~30 a), respectively; the SOCD of the P. Sylvestris var. mongolica plantations decreased first and then increased with the increase of the ages, and the SOCD of 0—60 cm soil depth was 79.38 t/hm²(6～10 a), 54.24 t/hm²(11～15 a), 75.52 t/hm²(16～20 a) and 82.24 t/hm²(＞20 a), respectively. [Conclusion] The effect of afforestation on SOC content and storage depends on the initial conditions of forested land and the tree species; in Yudaokou area, afforestation using L. principis-rupprechtii and P. Sylvestris var. mongolica pine in places with lower SOC content can increase SOCD, and L. principis-rupprechtii can increase SOCD more than P. Sylvestris var. mongolica.

Abstract:[Objective] The effects of microplastic type and size on the infiltration process of carbonatite laterite soils was investigated in order to provide new data revealing the hydrological processes of microplastic-contaminated agricultural soils. [Methods] The effects of polyethylene (PE), polypropylene (PP), and polystyrene (PS) microplastics with different particle sizes (550, 150, and 50 μm) on the infiltration rate, cumulative infiltration, and the depth of the wetting front of the lateritic soil were investigated by an indoor simulation of infiltration into a flattened soil column using a fixed-head vertical infiltration method. The effects of the cumulative infiltration, Philip, Horton, and Kostiakov models on the infiltration rate of the lateritic soil, cumulative infiltration, and the depth of the wetting front were also evaluated. The five hydraulic parameters (θ_r, θ_s, α, n, K_s) were inverted under different microplastic treatments using the Hydrus-1D model. [Results] ① The infiltration rate and cumulative infiltration of PS microplastics increased with decreasing particle size, while the cumulative infiltration and infiltration rate of PE and PP microplastics increased and then decreased with increasing particle size, and the differences in cumulative infiltration between different particle sizes were significant (p＜0.05); PS microplastics facilitated and then inhibited water transport, while both PP and PE played the role of facilitating water transport. ② All models were applicable to the infiltration simulation of microplastic-containing laterite soils, with Horton’s model and the cumulative infiltration model performing the best (R², CE > 0.98). ③ The effect of microplastic treatment on soil hydraulic parameters (θ_r, θ_s, α, n, K_s) was insignificant, but the PS microplastic saturated hydraulic conductivity showed an increase with decreasing particle size. [Conclusion] The effects of PS, PP, and PE microplastics on soil infiltration processes were significantly different, and the Horton, cumulative infiltration, and Hydrus-1D models showed high applicability.

Abstract:[Objective] The influence of overlying carbonate red soil on the infiltration characteristics of phosphogypsum was analyzed in order to provide an scientific basis for the rational disposal and utilization of phosphogypsum storage yards in southwest karst areas. [Methods] The influences of three phosphogypsum bulk densities (1.2, 1.3, 1.4 g/cm³) and three overburden thicknesses (0, 6, 12 cm) on the water infiltration process of phosphogypsum were studied through an indoor flat soil column infiltration test, and the infiltration process was numerically simulated using the improved layered Green-Ampt model. [Results] ① The difference in water infiltration time to the bottom between the 6 cm and 12 cm soil cover treatments was not significant (p>0.05). However, significant differences in infiltration time were observed between the 0 and 6 cm treatments, as well as between the 0 and 12 cm treatments (p<0.05). The initial infiltration rate, average infiltration rate, and stable infiltration rate of the 0 cm soil cover were significantly higher than those of the 6 and 12 cm soil cover (p<0.05), and the stable infiltration rate decreased significantly with the increase in soil cover thickness. There was no significant difference in cumulative infiltration between the 6 and 12 cm cover soil thicknesses (p>0.05), but there was a significant difference among the other cover soil thicknesses (p<0.05). ② For the same cover thickness, the influence of phosphogypsum bulk density on the initial infiltration rate, average infiltration rate, and stable infiltration rate was not significant (p>0.05). ③ The coefficient of determination (R²) between the measured and simulated values of the wetting peak depth varied was 0.951—0.995, the root mean square error (RMSE) ranged was 12.174—40.856, and the average absolute percentage error (MAPE) ranged was 0.070—0.227. When the soil was covered at 6 and 12 cm, the variation range of the determination coefficient (R²) between the measured and simulated values was 0.963—0.999, the root mean square error (RMSE) was 1.471—11.201, and the average absolute percentage error (MAPE) was 0.046—0.169. [Conclusion] There were significant differences in soil water infiltration characteristics between phosphogypsum-covered soil and uncovered soil, and the improved layered Green-Ampt model could be used to simulate the infiltration process of phosphogypsum under the condition of overlying soil.

Abstract:[Objective] Changes in soil properties and microbial community structure in 0—20 cm soil under different land use modes in wetlands were analyzed, and the characteristics of soil carbon sequestration microbial communities and functional gene changes under different land use modes were explored to provide scientific references for the protection and sustainable utilization of wetland ecosystem resources. [Methods] The Xianshan Lake National Wetland Park in Changxing, Zhejiang Province was taken as the research object. High-throughput sequencing technology was used to sequence the genes. [Results] ① The carbon sequestration capacity of the Xianshan Lake wetland was as follows: sedge swamp>natural coastal forest>bamboo forest>nursery>artificially intervened riverbank forest (Chinese fir forest)>artificial pine forest>broad-leaved forest>artificially intervened coastal vegetation>artificially intervened riverbank forest (willow swamp)>reed swamp>reed and willow coastal vegetation. The organic carbon storage of sedge swamp was the highest (38.68±0.56 t/hm²), accounting for 171% of forest organic carbon storage, and its soil microbial carbon utilization efficiency (0.66±0.005) was 150% of bamboo forest microbial carbon utilization efficiency. ② The carbon sequestration pathways of microorganisms in the Xianshan Lake wetland were mainly facilitated through the Calvin cycle, reducing the tricarboxylic acid cycle and reducing acetyl CoA pathway, with Proteobacteria, Bacteroidetes, Acidobacteria, and Chloroflexia as the main carbon sequestration microbial communities. The relative abundance of Proteobacteria and Bacteroidetes in the sedge swamp soil were 56.40% and 17.40%, respectively. The relative abundance of Proteobacteria in the natural coastal forest soil was 59.60%, and that of Acidobacteria in the bamboo forest soil was 36.00%. There was a positive correlation between organic carbon storage and soil carbon-fixing bacterial abundance in the Xianshan Lake wetland. [Conclusion] The dominant microbial communities for carbon sequestration in the Xianshan Lake wetland ecosystem varied greatly, and changes in soil carbon sequestration microbial communities and functional genes under different land use patterns affected the carbon sequestration capacity of wetland microorganisms. Among them, soil organic carbon storage, total nitrogen content, and microbial carbon utilization efficiency were the highest in the sedge swamp, and its carbon sequestration functional genes were higher than those of other land-use methods. Therefore, sedge marshes have a high carbon storage capacity.

Abstract:[Objective] Spatial and temporal succession patterns and predictions of ecosystem carbon storage in the Miyun Reservoir basin from 1985 to 2035 were conducted to provide a scientific basis for the integrated protection and restoration of mountains, rivers, forests, fields, lakes, grasslands, and sands and the optimization of ecological compensation standards under the goal of “double carbon” in the basin. [Methods] The InVEST-PLUS model was used to analyze the spatial and temporal evolution patterns of carbon storage in the basin during 1985—2020, and the changing trend of carbon storage under three scenarios (natural development, cultivated land protection, and ecological protection) in 2035 was predicted. [Results] ① During 1985—2020, the ecosystem carbon storage of Miyun Reservoir basin showed a continuous growth trend, and the carbon storage increased by 4.03×10⁷ t in 35 years. The largest contributors to carbon storage were forest land, grassland, and cultivated land, which accounted for approximately 98% of the total carbon storage. ② In 2035, the carbon storage of the basin will tend to increase under the three simulation scenarios. In the protection scenario, owing to the increase in forestland area, carbon storage remains at a high level. ③ Carbon storage in the basin showed a spatial pattern of 'higher in the south-central part and lower in the west and northeast’. The south-central part corresponds to the mountainous landform of the basin, which was the core area of water conservation, and the forest coverage rate was higher, while the west and northeast were mainly distributed in grassland, cultivated land, and urban construction land, with relatively lower carbon storage. [Conclusion] Carbon storage is consistent with the spatial pattern of land use. The consolidation and improvement of ecosystem carbon storage can be promoted by increasing forests and grasslands through ecological construction, controlling the transfer of forest land, and reasonably controlling the expansion of construction land.

Abstract:[Objective] The response and vulnerability of carbon storage to land-use change in the Dawen River basin were analyzed in order to provide a reference for promoting the green and sustainable development of the basin and the land-use optimization management and control. [Methods] Based on land use data, the InVEST model was used to study the impact of land-use change on carbon storage evolution in the Dawen River basin from 2000 to 2020, and the potential impact index (PI) was used to assess the vulnerability of ecosystem carbon storage. [Results] ① During 2000—2020, the land-use structure of the study area changed significantly, with a sharp decline in cultivated land (316.44 km²) and a sharp increase in construction land (523.98 km²). The conversion of cultivated land into construction land was the primary type of land transfer. ② During 2000—2020, the carbon storage decreased by 1.09×10⁷ t, and the transfer of cultivated land to construction land was the leading factor in the decrease. The spatial distribution characteristics of basin carbon storage were “overall higher in the north and lower in the south, and significantly higher or significantly lower in local areas.” ③ During 2000—2020, the land use degree index increased by 8.12. The PI for the first and last 10 years was -1.33 and -1.42, respectively, indicating that the vulnerability of carbon storage services increased. [Conclusion] The reduction in cultivated land, grassland and forest land, and the expansion of construction land in the Dawen River basin have significant effects on carbon storage and its vulnerability. In future, carbon storage should be considered as an important reference factor in land-use planning to achieve an optimal balance of carbon storage functions.

Abstract:[Objective] The characteristics of cultivated land use transformation and the differences in spatial and temporal distribution of carbon emissions were analyzed to explore the mechanisms of influencing factors in the process of cultivated land use transformation carbon emissions, in order to provide scientific basis for the low-carbonization of cultivated land use. [Methods] Using land use data and the carbon emission coefficients, the temporal evolution characteristics of cultivated land use transformation and its carbon emissions from 2000 to 2020 in Hunan Province were shown at the county and 5 km grid scales. The spatial distribution characteristics of carbon emissions were identified and analyzed using the spatial autocorrelation method. The depth of the influence of factors and the degree of interaction between them were assessed using the optimal parameter Geodetector model. [Results] ① Throughout the study period, the area of cultivated land in Hunan Province decreased continuously. With frequent conversions between cultivated land and forest land, water areas, and construction land, carbon emissions showed a fluctuating and increasing dynamic change trend. ② A spatial autocorrelation analysis showed significant high-high and low-low concentration phenomena at both scales, indicating strong concentration distribution characteristics in both spatial and temporal dimensions. ③ The interactions among factors were stronger than those of single factors, with socioeconomic factors and locational conditions having significant explanatory power at both scales. [Conclusion] The effect of cultivated land use transformation on carbon emissions in Hunan Province is significant, with clear differences in carbon emission characteristics and drivers at different spatial scales. Future measures for carbon emission reduction measures and cultivated land use planning should be formulated both scientifically and rationally.

Abstract:[Objective] The spatial land use resources of Changsha-Zhuzhou-Xiangtan urban agglomeration were optimized from the perspective of carbon balance, in order to provide theoretical support for the sustainable development of the region’s society and economy. [Methods] The carbon sinks and carbon emissions of the Chang-Zhu-Tan urban agglomeration were calculated from a land use perspective. Using the carbon ecological carrying capacity coefficient and the carbon economic contribution coefficient, carbon balance zoning was conducted, and land use optimization strategies were proposed for each type of city and county. Economic benefits, carbon sink benefits, compactness, and conversion costs were set as optimization functions for a multi-objective algorithm, achieving a more scientific optimization of land use spatial structure using the CoMOLA model. [Results] ① From 2000 to 2020, the total carbon emissions of the Chang-Zhu-Tan urban agglomeration increased annually, while the carbon sink levels in various districts and counties remained relatively stable, with an overall slight decline. ② Based on the carbon ecological carrying capacity coefficient and the carbon economic contribution coefficient, the Chang-Zhu-Tan urban agglomeration was classified into carbon sink development zones, economic development zones, comprehensive optimization zones, and green development zones. ③ The optimized land use increased economic benefits by 28.5%, carbon sink volume by 4.2%, and compactness by 3.6%. [Conclusion] The optimized land resources effectively meet the needs for economic and ecological sustainable development in the Chang-Zhu-Tan urban agglomeration, with a more rational spatial arrangement of land. This provides a decision-making basis for future land resource allocation.

Abstract:[Objective] The spatial-temporal changes and their causes of soil and water conservation services in the Sanjiangyuan region were explored in order to provide scientific evidence and data support for environmental protection measures and sustainable development in the area. [Methods] The soil and water conservation service capacity of the Sanjiangyuan region from 2000 to 2020 was quantitatively assessed using the net primary productivity (NPP) method and a driver factor analysis was performed using the optimal parameter geographical detector. [Results] ① From 2000 to 2020, land use in the Sanjiangyuan region underwent significant changes. The cultivated land, grassland, water bodies, and construction land continuously expanded, whereas the forest land and unused land areas decreased. The region is mainly dominated by grassland, followed by water bodies and forest land. Over the 20 year period, vegetation coverage showed a generally stable increasing trend with an overall spatial distribution pattern of “higher in the east and lower in the west.” ② From 2000 to 2020, the soil and water conservation service capacity index followed an N-shaped trend, but overall, the index had an increasing trend over the time period with a growth rate of 26.13%, indicating a significant improvement in the soil and water conservation service capacity. The distribution of the soil and water conservation service capacity was relatively consistent, displaying an overall “higher in the east and lower in the west” spatial distribution pattern. Throughout this period, the gravity center in the Sanjiangyuan region remained in the western part of Maqin County, with increased soil and water conservation capacity towards the northwest and multidirectional extension. This result indicated the engineering projects that had been implemented had significantly improved soil and water conservation service capacity. ③ Factors, such as vegetation coverage, GDP per unit area, and grazing intensity, had considerable impacts on soil and water conservation services and the interactions between vegetation coverage and GDP per unit area, average annual rainfall, grazing intensity, and other factors explained a considerable proportion of the change. [Conclusion] It is essential to continue implementing natural forest protection projects and promote forest conservation and restoration to significantly enhance the forest stock. Furthermore, measures, such as rational grazing, construction of artificial grasslands, fencing, and reseeding, should be adopted to protect ecosystems.

Abstract:[Objective] The influence of urban parks and surrounding landscape patterns on the cold island effect in Fuzhou City, Fujian Province, was analyzed, and the cooling impacts and landscape configurations of parks with different types of cold island effect were quantified. in order to provide a scientific basis for understanding the cold island effect of urban parks and alleviating high urban temperatures. [Methods] Twenty-three parks were selected from the list of urban parks in Fuzhou City, and the radiative transfer equation was used to invert the land surface temperature based on Landsat 8 and GF-1 as well as other remote sensing data. For each park, the correlations between the scale, shape, internal and surrounding landscape components, vegetation coverage, building height, and economic development and the exerted cold island effect were analyzed. A logarithmic function curve was fitted between park area and the cumulative gradient of the cold island effect to calculate the cooling efficiency threshold. The cooling effect was used as basis to divide the types of cold island effect of parks, and the respective cooling characteristics and park configurations were analyzed. [Results] ① The heat island effect in the main urban area of Fuzhou City was significant, and the cooling effect of the parks was obvious provided noticeable cooling. ② The cold island effect of parks was significantly correlated with the scale, shape, and internal and surrounding landscape components and weakly correlated with vegetation coverage, while there were no significant correlations with building height and economic development. ③ The cooling efficiency threshold of parks in Fuzhou City was 0.22 hm². ④ The types of cold island effect of parks were divided into strong, sub-strong, and low based on the normalized average temperature and cumulative gradient of the cold island effect. Each type hads distinct cooling effects and landscape patterns suitable for suburban, urban, and crowded areas with limited land. [Conclusion] Future park planning and layout should consider the types of cold island effect of parks and respective landscape patterns, and park scale and landscape composition should be rationally distributed to minimize the park scale and achieve maximum alleviation of the urban heat island effect.

Abstract:[Objective] The spatial and temporal variations in urban land green utilization efficiency and the influencing factors were investigated to provide a scientific basis for optimizing the development and protection patterns of national land space and promoting the sustainable development of urban land. [Methods] The slack-based measure-directional distance function (SBM-DDF) model was used to measure the land green utilization efficiency of urban land in Anhui Province from 2008 to 2022. Kernel density analysis and center of gravity migration models were selected to analyze the spatial and temporal variations, while the geodetector and geographic time weighted regression (GTWR) models were combined to study the factors influencing urban land utilization efficiency. [Results] ① The average value of green land utilization efficiency of urban land in Anhui Province from 2008 to 2022 was 0.77 and was divided into two phases: a straight-line decline from 2008 to 2014 and a fluctuating increase from 2015 to 2022. ② Polarization phenomena were observed in the region, with the low value of the city increasing, the high value being more stable, and the regional gap gradually expanding. The gravity center trajectory of efficiency value of the whole province moved first to southeast and then to northwest, and the improvement was more obvious in northwest than in southeast. Although it remained high in the south and low in the north, indicating unbalanced spatial characteristics. ③ The leading factors were environmental protection inputs, urban and rural structures, urban greening, environmental regulation, and industrial structure, the interaction between industrial structure and environmental protection inputs was the strongest, with a q-value of 0.82. The spatial heterogeneity of the leading factors was significant: urban greening influenced all cities positively; urban and rural structure, environmental regulation, and environmental protection inputs influenced the central and southern regions positively and the northern region negatively; and the industrial structure influenced the resource cities negatively. Industrial structure has a significant negative influence on resource-oriented cities. [Conclusion] Strict land use control, promotion of industrial structure upgrading, increasing ecological and environmental protection, strengthening overall collaborative development, and formulating differentiated development paths should be used to promote the overall improvement of green land use efficiency in the urban areas of Anhui Province.

Abstract:[Objective] The spatial and temporal characteristics of ecological environment quality and its driving factors in the Weihe River basin from 2000 to 2020 was analyzed in order to provide theoretical reference for the sustainable development and ecological civilization construction in the basin. [Methods] The remote sensing ecological index (RSEI) was built based on Google Earth Engine platform to dynamically evaluate the change of ecological environment quality in the Weihe River basin from 2000 to 2020 and the impact of climate, vegetation, terrain, soil and social-economic factors on ecological environment quality was explored based on the optimal parameter geographic detector model. [Results] ① From 2000 to 2020, the quality of the Weihe River basin ecological environment continuously improved and the difference in ecological environment quality within the region increased. The ecological environment quality grade was mainly poor and relatively poor, accounting for more than 60% of the total area. In 20 years, the area of ecological environment quality grade increased for medium, good, and excellent. ② The quality grade of the ecological environment had a spatial distribution pattern of “higher in the south and lower in the north, higher and lower in the east and the west”. The area of poor grade ecological environment was the largest, and 73.43% of the Weihe River basin was in the area of ecological environment quality increase, with an increase area of 1.21×10⁵ km². During the study period, the area where the ecological environment quality increases was increasing and the reduced area was decreasing, and the overall ecological environment quality of the research area was positively developing. The area with excellent ecological environment quality distributed along the southeast-northwest direction. [Conclusion] Rainfall, elevation, and soil organic carbon content were the main factors affecting the ecological environment quality of the Weihe River Basin. In the process of improving the ecological environment quality of the Weihe River Basin, the distribution law of slope should be fully considered to optimize the governance scheme.

Abstract:[Objective] The gradient effects of different topographic factors on land-use patterns over 23 years from 2000 to 2023 at the arsenic sandstone area of the Yellow River were analyzed in order to provide theoretical guidance for vegetation restoration and land use optimization in this area. [Methods] Using remote sensing data to extract critical topographic factors, such as elevation, slope, and topographic position, and combining these with GIS-based quantitative analysis, the gradient effects of various topographic factors on land-use patterns were analyzed, and the graded evolution of land-use types according to a comprehensive topographic index was explored. [Results] ① Grassland was the dominant land use type in the study area, and from 2000 to 2023, the areas of forestland and construction land underwent the most significant change, followed by cultivated land and unused land. Forestland increased by 10.48 km², whereas construction land increased by 295.40 km², mainly from the cultivated land and grassland. The cultivated and unused land areas decreased by 1,716.52 km² and 758.89 km², respectively, while grassland increased by 548.12 km². ② The spatial distribution of land use in the study area exhibited distinct gradient characteristics: cultivated land, construction land, and unused land were primarily distributed in low topographic positions, forestland was mainly located in high topographic positions, and grassland was concentrated in mid-to high-elevation areas. Meanwhile, the water bodies were predominantly found in both low and high topographic positions. ③ In 2000, the highest comprehensive land use index was 220.99, and the lowest was 205.69. By 2023, the highest index was 230.17, and the lowest was 203.36. Except for Levels 1 and 2, the comprehensive land use index in 2023 was significantly lower than that in 2000. Over the past 23 years, land use changes have been closely related to human activities. [Conclusion] From 2000 to 2023, the arsenic sandstone area of the Yellow River exhibited evident topographic gradient characteristics, with significant spatiotemporal changes in land-use types along the topographic gradient. Considering the influence of local topographic factors, it is advisable to strengthen the implementation of policies, such as returning farmland to forests and grasslands, and to optimizing the land use layout continuously.

Abstract:[Objective] The spatiotemporal changes and factors influencing soil conservation capacity in Linyi City, Shandong Province, before and after the implementation of the “Mountain-River Project” were investigated, in order to provide scientific support for evaluating the project’s effectiveness and future planning in the region. [Methods] Using the InVEST model, the spatiotemporal characteristics of the soil conservation capacity in Linyi City of the years 2018, 2020, and 2022 was assessed. The response relationship between the soil conservation capacity and influencing factors was analyzed from both temporal and spatial dimensions. [Results] The soil conservation capacity of Linyi City in 2018, 2020, and 2022 was 23.12, 29.62, and 53.70 t/(hm²·a), respectively. Spatially, soil conservation capacity showed a pattern of “higher in the northwest-lower in the southeast.” Among the four main influencing factors, precipitation, soil, topography, and vegetation, topography was the primary factor affecting spatial distribution, whereas interannual variation was mainly driven by precipitation. [Conclusion] The soil conservation capacity of Linyi City showed a significant upward trend with distinct spatial and interannual variations. Precipitation plays a more prominent role than ecological engineering in influencing the interannual variation in soil conservation capacity; however, the contribution of ecological engineering has increased.

Abstract:[Objective] The agglomeration characteristics and evolution trend of land use conflicts was scientifically identified to provide important reference for promoting the rational layout of territorial space and regional sustainable development. [Methods] The spatial-temporal evolution trend of land use conflict in the Wanjiang urban belt from 1990 to 2020 was quantitatively analyzed by constructing a land use conflict measurement model based on the landscape index. The distance weight matrix was determined by setting the optimal spatial threshold to explore the agglomeration effect of land use conflict more accurately. [Results] ① Significant changes occurred in the land use structure of the Wanjiang urban belt from 1990 to 2020. The area of cultivated and forest land decreased continuously, and the scale of construction land increased significantly. ② The distribution pattern of regional land use conflicts was “higher in the north and lower in the south,” with areas of weak and medium spatial conflicts occupying the main position. Serious conflict areas were concentrated in Hefei City, Wuhu City, Jin’an District of Lu’an City, and the coastal areas on both sides of the Yangtze River system. ③ The land use conflict index changed significantly in urban areas during the study period, especially in the east of Hefei City, the north of Wuhu City, and the southeast of Chuzhou City. Under the influence of urbanization, the conflict gravity center gradually shifted southward, and the serious conflict zone shifted from the northwest to the southeast. ④ 5 km was selected as the optimal distance analysis threshold. The high-high aggregation conflict zone was centered on Hefei City, while the low-low aggregation conflict zone showed no agglomeration phenomenon. [Conclusion] The land use conflict in Wanjiang urban belt has the potential to intensify, and the main conflict areas show a shifting trend. In the future, it is necessary to strengthen the rational distribution of regional land use and focus on the balance and stability between urbanization development and ecological protection.

Abstract:[Objective] The functional composition of the soil and water conservation ecological services in Mudanjiang City, Heilongjiang Province, China, was constructed from the perspective of ecological priority. The spatiotemporal differentiation characteristics, tradeoffs and synergies of regional soil conservation, carbon sink of soil and water conservation, and water purification capacity were explored, and the intensity of regional soil and water conservation ecological services was calculated, providing scientific basis for maintaining regional ecological stability, ensuring the sustainable development of agriculture, and improving hydrological connectivity and water quality. [Methods] The main watershed and sub-watershed of Mudanjiang City were divided using the SWAT model, and the soil and water conservation ecological service functions (soil conservation, carbon sink of soil and water conservation, and water quality purification) were quantitatively evaluated and analyzed in terms of space and time in each watershed for 2002, 2012, and 2022 using the InVEST model. The soil conservation function was analyzed using bivariate spatial autocorrelation analysis at the grid scale based on the Geoda software. We studied the tradeoff and synergistic relationships between the different service functions and their temporal changes and calculated the ecological service intensity of soil and water conservation in Mudanjiang City by combining numerical and weighting methods. The contributions of rainfall and the digital elevation model to each service function were explained using geographic detectors. [Results] The soil conservation and soil and water conservation carbon sink functions in Mudanjiang City exhibit a synergistic relationship, whereas the water quality purification function exhibits tradeoff relationships with both the soil and water conservation carbon sink and soil conservation functions. The average ecological service intensities of soil and water conservation in 2002, 2012, and 2022 were 0.327 5, 0.325 6, and 0.332 7, respectively, showing a slight decrease followed by an increase. [Conclusion] The soil and water conservation ecological service functions in Mudanjiang City improved compared to the case in the initial study period, with the average value in Suifenhe River basin being better than those in other regions and Mudanjiang River basin contributing the most to the total. The spatiotemporal heterogeneity characteristics of the service functions are affected by precipitation, topography, land use change, and vegetation coverage.

Abstract:[Objective] Based on bibliometrics, research hotspots and trends in the field of plant-soil reinforcement were explored to provide a reference and guidance for the research status and development in this field. [Methods] Using the CNKI (China National Knowledge Infrastructure) and Web of Science (WoS) databases as data sources, a combined approach using VOSviewer and CiteSpace was employed for the visual analysis of publication volumes, countries, institutions, researchers, and keywords in the field of plant-soil reinforcement from 1993 to 2023. [Results] ① The volume of publications showed a slow increase followed by a sustained rapid growth, with the publication volume in CNKI stabilizing in recent years while that in WoS surged. ② China has produced the most research results on plant-soil reinforcement, but there was still room for improvement in research quality. Beijing Forestry University, Yunnan Agricultural University, and Inner Mongolia Agricultural University were the three major institutions in the field of plant-soil reinforcement. While the collaborative publication of literature showed that the team has close cooperation within the institution it lacks cooperation outside the institution. ③ Research in the field of plant-soil reinforcement focused on slope stability, root mechanics, and root-soil shear resistance. Keyword analysis showed that WoS emphasized erosion prediction, the Loess Plateau, and mechanical properties, whereas CNKI highlighted root morphology, drawdown zones, mechanical characteristics, self-repair, and ecological restoration as research hotspots over the past three years. [Conclusion] China has the highest research output in this field; however, there is room for improvement in research quality and collaboration among teams and institutions. Most studies have focused on herbaceous plants and have had relatively short durations. Future research should deepen the study of other plant types and longer durations. In addition, research on ecologically vulnerable areas remains limited, indicating the need to expand the scope of future research.

Abstract:[Objective] This study aimed to clarify the spatiotemporal pattern evolution law of the coupling coordination between the recessive form of urban land use and ecological welfare performance, reveal the direction of its influencing factors, and provide a scientific basis for promoting the green development of urban agglomerations along the Lower Yellow River. [Methods] Based on panel data from 17 prefecture-level cities along the Lower Yellow River from 2012 to 2021, the comprehensive index and Super-SBM models were used to measure the recessive form of land use and ecological welfare performance. In addition, ArcGIS visualization, kernel density analysis, and a coupled coordination model were used to deply analyze the evolution trend of the recessive form of land use, the performance level of ecological welfare, and the coupling coordination degree of them in the spatial and temporal dimensions, with the influencing factors analyzed using the Tobit regression model. [Results] ① The recessive form of land use in each city was stable but improved, and the ecological welfare performance experienced a phased evolution process of “first decreasing and then increasing.” ② During the study period, the coupling coordination degree of the overall ecological welfare performance and the recessive form of land use of cities along the Lower Yellow River experienced a change from “near disharmony to barely coordination,” and tended to change to primary coordination. ③ Opening to the outside world, industrial structure, and spatial agglomeration had significant positive effects on the coupling coordination; but scientific and technological innovation and the urban environment had obvious inhibitory effects on the coupling coordination. Meanwhile, elevation, slope, and education level did not affect the coupling coordination. [Conclusion] In the future, it is necessary to promote the rational use of land according to local conditions, formulate scientific environmental protection policies, strengthen the monitoring and management of cities, strengthen the leading role of provincial capitals, and promote green coordinated development among cities.

Abstract:[Objective] The coupling and coordination relationship between soil and water conservation policy and agricultural eco-efficiency, and its driving factors were analyzed to provide a new perspective and thinking for further understanding of the coordination relationship between soil and water conservation policy and agricultural eco-efficiency. [Methods] An evaluation index system for soil and water conservation policy intensity and agricultural eco-efficiency was established using the Three Gorges reservoir (Chongqing section) as the research area. The coupling coordination degree model, geographical detector model, and ordinary least squares (OLS) regression were used to analyze the coupling relationship between the soil and water conservation policy and agricultural eco-efficiency, and its driving mechanism in the region from 2015 to 2022. [Results] ① There were significant differences in policy intensity and ecological efficiency among regions in the Three Gorges reservoir area (Chongqing section). The maintenance area of soil-conserving human settlements in the Fangshan Hills and parallel ridges and valleys showed strong growth momentum during policy implementation, whereas the rest of the region was relatively stable. The agricultural ecological efficiency of the urban landscape living environment maintenance area was excellent, whereas that of the Wuling Mountain water and soil conservation areas was relatively low, showing an obvious polarization trend. ② The degree of coupling coordination between soil and water conservation policies and agricultural ecological efficiency showed an overall upward trend, and the coordination degree of the urban landscape human settlement environment maintenance area and the Fangshan hilly soil conservation human settlement environment maintenance area was particularly prominent. However, there was a significant imbalance of that in Kaizhou District in the areas of soil conservation and human settlement in the parallel ridge valley of Yuzhong. ③ The input of farmland water conservation facilities was helpful in improving the coordination level, and reasonable control of the planting area could also more positively affect the coordination relationship between the soil and water conservation policy and agricultural ecological efficiency. The robustness of the regression results is confirmed using a counterfactual test. [Conclusion] To effectively maintain soil and water resources and agricultural ecological security, the Three Gorges reservoir area (Chongqing section) should adhere to the principles of local governance and regional linkages, actively guide all parties in society to participate in the formation of governance synergy, and jointly promote the development of a diversified support model combining poverty alleviation, soil conservation, and agricultural assistance.