• Volume 43,Issue 6,2023 Table of Contents
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    • >Experimental Research
    • Characteristics of Changes in Factors Influencing Wind Erosion and Erodibility of Soils in Mu Us Sandland During Desertification Reversal

      2023, 43(6):1-9. DOI: 10.13961/j.cnki.stbctb.2023.06.001

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      Abstract:[Objective] The influences of the desertification reversal process on soil wind erosion in the Mu Us sandland were studied in order to provide a scientific reference for the prevention and control of wind erosion and for ecological reconstruction in this area. [Methods] A total of eight remote sensing images were selected from 1986 to 2021, and ENVI 5.3 and ArcGIS 10.7 were used as the platform to invert the desertification of land in different periods in the Mu Us sandland. A desertification difference index (DDI) was constructed for the study area in 2021, and land in the Mu Us sandland was classified as non-, light, moderate, severe, and very severe desertification according to the natural fracture method. According to the inversion results, we applied the method of space instead of time to collect soil samples of different desertification types. We tested the soil samples and analyzed them for soil wind erosion erodibility influencing factors, such as soil mechanical composition, soil organic matter content, soil crust factor, and vegetation factors. [Results] The overall desertification of the Mu Us sandland tended to decline from 1986 to 2021, and the desertified land area shrank from 47 877.81 km2 in 1986 to 45 914.06 km2 in 2021 (a reversal rate of 56.11 km2/a). Desertification could be divided into three periods:1986-2001 was the desertification development period that exhibited decreasing trends for soil clay, silt, and organic matter content, and increasing trends for soil sand content, soil crust factor, and vegetation factors; 2001-2011 was the period of significant desertification reversal; and 2011-2021 was the desertification stabilization period. During the reversal period, the percentage content of soil clay, silt, and organic matter showed an increasing trend, and the soil sand grain percentage content, soil crust factor, and vegetation factors showed a decreasing trend. The greater the degree of reversal, the faster the rate of change of the factors. As desertification degree weakened, the percentage content of soil clay, silt, and organic matter showed a linear increasing trend, with increasing rates of 1.55%, 7.08% and 1.98%, respectively. The values of soil sand grain percentage, crust factor, and vegetation factors showed a linear decreasing trend, with decreasing rates of 8.62%, 0.13% and 0.23%, respectively. [Conclusion] The reversal process of desertification in the Mu Us sandland caused soil structure to become finer, crusts to develop, vegetation to increase, and soil erosion resistance to increase, thereby significantly inhibiting wind erosion of soil.

    • Soil Water Characteristics of Different Aerial-seeded Plant Communities at Northeastern Edge of Tengger Desert

      2023, 43(6):10-17. DOI: 10.13961/j.cnki.stbctb.2023.06.002

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      Abstract:[Objective] Soil water characteristics of different plant communities at different slope positions on aerial-seeded afforestation areas in 1992 were studied at the northeastern edge of the Tengger Desert in order to provide a theoretical basis for the rational construction and management of an artificial sand fixation vegetation system in the arid desert areas of Northwest China. [Methods] Soil water contents at the depth of 200 cm for different plant communities at different slope positions were measured using the ring knife method. The water distribution, variability and water storage deficit of soilwere analyzed. [Results] ① The average soil water contents of different plant communities followed the order of Hedysarum scoparium community (0.57%) >Calligonum mongolicum community (0.54%) > H. scoparium+C. mongolicum community (0.51%) > C. mongolicum+H. scoparium community (0.51%). There was a significant difference (p<0.05) between the H. scoparium and the H. scoparium+C. mongolicum communities, as well as the C. mongolicum+H. scoparium community. The average soil water contents at different slope positions followed the order of bottom slope > middle slope > top slope. The vertical variability of soil water in the two combined communities of H. scoparium and C. mongolicum, and its variability with slope position were significantly smaller than the vertical variability of soil water in the H. scoparium and C. mongolicum communities. ② The variation range of total soil water storage in different plant communities was between 15.45 mm and 17.79 mm, and the trend of soil water storage with soil depth was consistent with soil water content. ③ Soil water storage deficits for the different plant communities followed the order of H. scoparium+C. mongolicum community (97.74%) > C. mongolicum+H. scoparium community (97.62%) > H. scoparium community (97.48%) > C. mongolicum community (97.44%). [Conclusion] Soil water content was relatively low (less than 1%). Soil water content at the bottom of the sand dune was greater than at the middle slope and top slope positions, and soil water content increased with soil depth. The vertical variability of soil water content in the H. scoparium and C. mongolicum combined communities was lower than the soil water content of the single species communities. Therefore, a plant community comprised of a combination of H. scoparium and C. mongolicum can utilize soil water to a greater extent, has greater water absorption, and uses soil water more efficiently. These combination plant communities are better adapted to arid environments.

    • Flume-based Experimental Study on Wave Prevention and Sand Fixation Functions of Sand Barriers Applied to Coral Sandy Coastlines

      2023, 43(6):18-24. DOI: 10.13961/j.cnki.stbctb.2023.06.003

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      Abstract:[Objective] The flume simulation research on wave prevention and sand stabilization counter measures for coral sandy coastlines were studied in order to provide a theoretical basis for the project to protect coastlines against wave erosion along the Dengloujiao shoreline, located in the Xuwen National Coral Reef Nature Reserve on the Leizhou Peninsula, and to provide technical support for similar coastal areas. [Methods] The coastal erosion protection effect of san-dbag barrier measures was determined for the Dengloujiao coastline using a flume experiment simulation method. [Results] ① The composite effect of the overall structure of the diamond-shaped sand-bag barrier had a significant impact on the stability of the sand barrier. Two groups of sand barriers with a diameter of 5 cm or above was able to achieve self-stability. Calculated according to the gravity similarity criterion, this was equivalent to 50 cm diameter of the prototype; ② The sand-bag barrier achieved sediment fixation by increasing the roughness of the bed surface, weakening the hydrodynamic strength, and thereby reducing the intensity of sediment transport. As the diameter of the sand barrier increased, its shielding effect became more significant; ③ For a wave period of 1.90 s and a water depth of 0.4 m, the height of sand ridges observed in the experiment were 3-4 cm. Therefore, in practical projects, sand barriers with a diameter of 50 cm or more can prevent and control the migration of sand waves and sand ridges; ④ The sand barrier arranged in a diamond shape was less affected by oblique waves and had better stability than the sand barrier arranged in a normal direction. Therefore, it is advisable to use a diamond-shaped sand barrier to reduce the effect of oblique waves. [Conclusion] The use of sand-bag barriers as protective materials for coastal erosion not only achieved the goal of sand control, but also produced favourable ecological and environmental protection effects. These results could provide important scientific guidance and have significant and practical promotion value.

    • Population Structure Characteristics and Survival Status of Natural Platycladus Orientalis in Loess Hilly Region

      2023, 43(6):25-30,39. DOI: 10.13961/j.cnki.stbctb.2023.06.004

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      Abstract:[Objective] Population structure characteristics and survival status of natural Platycladus orientalis in the loess hilly region were determined in order to provide a scientific basis for high-quality and sustainable development of forest grassland in this area. [Methods] Characteristics were quantitatively analyzed by using a dynamic change index based on a static life table combined with spectral analysis on the time scale and time series simulation prediction to carry out a comprehensive survival analysis of this cypress species. [Results] ① The height, crown width, and diameter structure of the P. orientalis population indicated that young trees were abundant. ② The survival curve of the P. orientalis population was close to Deevey-Ⅱ type, and the population was sensitive to external interference. ③ Population dynamics were characterized by strong viability in the early stage, stable growth in the middle stage, and decline in viability in the later stage. Time series simulation and prediction analysis showed that the population of P. orientalis showed different degrees of increasing trend and strong growth recovery ability. [Conclusion] The natural population structure of P. orientalis in the loess hilly region was stable and growing, and the survival curve was close to that of Deevey-Ⅱ type.

    • Construction Experiment and Mechanical Modeling of Soil-Concrete Composite Slope Protection Technology

      2023, 43(6):31-39. DOI: 10.13961/j.cnki.stbctb.2023.06.005

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      Abstract:[Objective] The construction and mechanical model of soil-concrete composite slope protection technology were analyzed in order to provide scientific reference for the implementation of slope modification engineering in soil-rock mountain area. [Methods] Using a slope damage mechanism based on the basic principles of geotechnics, we proposed the slope stability design concept of "retaining soil with soil". We used this basic design concept, combined with construction experiments to establish a stability calculation mechanics model of "soil-concrete composite", and also provided design suggestions for medium-high slopes. [Results] After nearly six years of construction experiments and operation, the rationality of the slope stability design concept of "retaining soil with soil" was verified. The two scientific models of "soil-concrete composite" (i.e., critical equilibrium state and ultimate equilibrium state) and their supporting formulas were also verified. Compared with traditional stone slopes, the "soil-concrete composite" slope protection technology could save more than 80% of the materials used in construction, and could accelerate construction speed by more than five times, with the initial construction cost being no higher than the cost of the stone slope. [Conclusion] Soil-concrete composite slope protection can replace the traditional stone bank slope protection, thereby effectively alleviating the conflict between slow construction speed and schedule requirements, as well as the conflict between the large amount of stone material needed for construction and the environmental protection aspects of quarrying. The soil-concrete composite slope protection technology has broad application prospects in the future.

    • Simulation Experiment on Effect of Surface Cracks Caused by Coal Mining on Soil Moisture Disturbance in Loess-Covered Area

      2023, 43(6):40-48. DOI: 10.13961/j.cnki.stbctb.2023.06.006

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      Abstract:[Objective] The effect of surface cracks caused by coal mining on soil moisture changes in a loess-covered area was studied in order to provide data support for the study of soil moisture changes in coal mining subsidence area. [Methods] The study was conducted in a coal mining subsidence location in a loess-covered area. A self-developed mining subsidence surface crack simulation device was used to carry out physical simulation experiments. Soil moisture sensors were set around the cracks to analyze the characteristics of soil moisture changes caused by surface cracks. Hydrus software was used to build the hydrological models and to optimize them using the results of physical simulation experiments. The control variable method was used with the optimized model to calculate the differences between soil moisture content around surface cracks and soil moisture content in non-deformation areas under different fracture shapes, topography, and initial water contents. [Results] Crack width mainly affected the maximum crack-induced soil moisture loss. Crack depth mainly affected the location of the maximum crack-induced soil moisture loss. There were differences in the influence of cracks in the uphill direction and in the downhill direction. The larger the slope was, the more obvious the differences were. The smaller the initial soil moisture content was, the smaller the soil moisture disturbance by cracks was. When the initial soil water content was less than 20%, the impact of surface cracks on soil moisture was less than 15 cm away from the crack. [Conclusion] Under the same boundary conditions, the soil moisture simulation results were consistent with the changes observed in physical experimental results. The optimized hydrological model could be used to quantitatively analyze the disturbance characteristics of soil moisture resulting from surface cracks in loess-covered areas.

    • Biological Characteristics of Periphytic Algae on Different Building Material Substrates in Water Eco-enrironment

      2023, 43(6):49-56. DOI: 10.13961/j.cnki.stbctb.2023.06.007

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      Abstract:[Objective] The biological characteristics of different attached algae were determined and the relation between water quality indicators and algae biological characteristics were analyzed in order to provide scientific support for screening scientifically reasonable attached substrates and enriching the growth of attached algae. [Methods] The biological characteristics of algae attached to three different building material substrates (granite, polyethylene mesh, wood) were analyzed using simulation experiments. The types of attached substrates having good effects and easy resource utilization were selected. [Results] The periphytic algae communities attached to granite and wood substrates were more stable, and had better biological characteristics and more functional algae species, and thereby were more conducive to providing an ecological effect of periphytic algae in the water environment. [Conclusion] The granite substrate was considered to be the most suitable substrate among the three tested substrates because of its ready availability and ease of use.

    • Mechanical Properties of Medicago Sativa and Euphorbia Hypericifolia Root-Soil Complex

      2023, 43(6):57-64. DOI: 10.13961/j.cnki.stbctb.2023.06.008

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      Abstract:[Objective] The effects of soil moisture content and root area ratio on the soil consolidation effect of Medicago sativa and Euphorbia hypericifolia root systems and the interaction mechanism of root-soil were studied in order to provide scientific basis for selecting plant species and controlling soil moisture content in ecological restoration of mines. [Methods] Wild M. sativa and E. hypericifolia were observed on a Haizhou open pit mine slope in Burin City, Liaoning Pvocince. Tests were conducted to determine the tensile properties of the root systems. The root-soil complex shear test was used to determine the optimum moisture content of the root systems of the two plants. The root-soil composite shear optimization test was conducted based on the optimal moisture content to determine the optimal root area ratio for soil consolidation efficiency. [Results] ① The tensile resistance of the root systems of the two species increased as a power function of root diameter. The tensile strength of the root systems decreased as a power function of root diameter. ② The cohesive force of the vegetative soil and the two root-soil complexes tended to increase and then decrease with increasing moisture content, and the angle of internal friction tended to decrease with increasing moisture content. ③ The M. sativa and E. hypericifolia root systems had the greatest soil consolidation effect when the moisture content was 25% and 21%, respectively. ④ At the optimal moisture content, the greatest soil consolidation efficiency was achieved when the root area ratios of the M. sativa and E. hypericifolia root systems were 0.04% and 0.08%, respectively. [Conclusion] The morphological and mechanical effects of the E. hypericifolia root system made it the superior species because of its greater soil consolidation than the M. sativa root system.

    • Effects of Desertification on Phosphorus Fractions of Alpine Meadow Soils

      2023, 43(6):65-71,88. DOI: 10.13961/j.cnki.stbctb.2023.06.009

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      Abstract:[Objective] Soil phosphorus fractions determine the migration and availability of phosphorus during soil evolution. The spatial distribution characteristics of soil phosphorus fractions in alpine meadows under different desertification levels were studied in order to provide a scientific reference for vegetation restoration in sandy meadows. [Methods] The modified Hedley phosphorus classification method was used to determine changes in phosphorus fraction in alpine meadow soils under different degrees of desertification (non-desertification; and light, medium and heavy desertification) using desertifed Zoige alpine meadow soils on the Qinghai-Tibet Plateau. [Results] ① Soil organic carbon, total nitrogen, total phosphorus, active phosphorus, and water content decreased significantly (p<0.05) with increasing sand content; pH value increased significantly (p<0.05). ② Soil Resin-Pi, NaHCO3-P, NaOH-P, D.HCl-Pi, and C.HCl-P contents all decreased significantly (p<0.05) with increasing sand content. Organic phosphorus fractions decreased more significantly than inorganic phosphorus fractions under moderate and severe desertification. ③ Correlation analysis showed that the conversion of soil phosphorus fractions during desertification in alpine meadows occurred mainly between D.HCl-Pi and NaHCO3-P and NaOH-Po. HCl-P, NaOH-P, and Resin-Pi were important phosphorus sources for plant growth. [Conclusion] Desertification produced significant effects on soil carbon, nitrogen, moisture and pH value, and on phosphorus fractions. Desertification also produced different degrees of variability in soil carbon, nitrogen, moisture, and pH value, and on phosphorus fractions, and mostly occurred in the middle and late stages of desertification. HCl-P, NaOH-P, and Resin-Pi were important phosphorus sources for plant growth in desertified alpine meadow soils.

    • Diurnal Variation Characteristics of Temperature and Water Content in Quicksand Surface Layer Under Different Protective Measures

      2023, 43(6):72-80,88. DOI: 10.13961/j.cnki.stbctb.2023.06.010

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      Abstract:[Objective] The variation of temperature and water content in a quicksand surface layer under different protective measures and their influencing mechanisms were investigated in order to provide a theoretical basis for vegetation restoration in a desert area. [Methods] Field tests were carried out to examine five protective measures (single pipe protection, pipe coated with reflective film, pipe wall opening, pipe covered with straw, and double-pipe protection), three pipe diameters (75, 90, 110 mm), and three open field heights (10, 15, 20 cm). The unprotected quicksand surface was used as the control. The diurnal variation characteristics of surface soil temperature and water content were measured using a soil temperature and water content recorder in the quicksand surface layer. [Results] The five protective measures contributed significantly to the cooling effect, with double-tube protection showing the best cooling effect. Under the same protective measures, the surface layer temperature of the pipe interior increased with increasing pipe diameter at 06:00 am, and decreased with increasing pipe diameter at other times. The surface layer temperature of the pipe interior decreased with increasing open ground height during the entire day. The surface layer temperature of the inner tube increased with the surface layer temperature of the quicksand surface layer. Additionally, there was a strong linear relationship between the surface layer temperatures of the inner tube and the quicksand (R2 ≥ 0.830). Irrigation cooled the surface layer during the daytime (06:00-21:00) and preserved heat during the nighttime (21:00-06:00). Furthermore, there existed a coupling effect between the surface layer water content and the temperature inside the pipe. This result signified that the higher the surface layer water content, the lower the temperature. [Conclusion] Double-pipe protection and irrigation were found to be the most beneficial to temperature control and water conservation in the surface layer of quicksand. The optimum pipe parameters were a pipe diameter of 110 mm and an open field height of 20 cm.

    • Spatial Distribution Characteristics of Soil Water and Salt in Newly Cultivated Farmland Under Gully Control in Loess Hilly Region

      2023, 43(6):81-88. DOI: 10.13961/j.cnki.stbctb.2023.06.011

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      Abstract:[Objective] Part of the newly cultivated farmland formed by the "Gully Control and Land Reclamation" project is facing the risk of soil salinization in the loess hilly region. The spatial distribution characteristics of soil water and salt and their influencing factors were studied for preventing and controlling soil salinization, and promoting sustainable utilization of newly cultivated land. [Methods] A typical area of newly cultivated land was selected, and six experimental plots were established along a gully head to the gully mouth, with sampling points numbered sequentially from 1 to 6. The grid method was used to obtain soil samples from the 0-20 and 20-40 cm layers in each plot. The multifractal method was used to analyze the spatial distribution characteristics of soil water and salt. [Results] Soil water content and salt content gradually decreased from the gully head to the gully mouth. The mean soil water contents and salt contents at sampling points 1, 2, and 3 were 17.6% and 0.81 g/kg, respectively, which were 23.0% and 14.1% higher than the respective values at sampling points 4, 5, and 6. Meanwhile, the multifractal parameters D1 of soil water and salt at sampling points 1, 2, and 3 were less than the respective values at sampling points 4, 5, and 6. ΔD values showed the opposite result, indicating that the spatial variability of soil water and salt at sampling points 1, 2, and 3 were higher. The depth of groundwater influence was the main reason for increased accumulation of salt in the surface soil at sampling points 1, 2, and 3 (p<0.05). The terrain characteristic was also an important reason (p<0.05). The narrow terrain was not conducive to drainage, was prone to waterlogging, and exhibited exacerbated salt accumulation. In addition, sampling points 1, 2, and 3 may be invaded by slope runoff and sediment with high salt content that increased soil water, salt content, and variability in the area. [Conclusion] The depth of groundwater influence, terrain characteristics, and slope runoff sediment were important reasons for the high soil water content, salt content, and their spatial variability at sampling points 1, 2, and 3 in newly cultivated farmland. Thus, newly cultivated farmland near the gully head location would be a key area for preventing soil salinization in the future.

    • Effects of Ecological Restoration Measures of Fish-scale Pit on Soil and Water Conservation in Bashang Grassland

      2023, 43(6):89-97. DOI: 10.13961/j.cnki.stbctb.2023.06.012

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      Abstract:[Objective] The effects of fish-scale pits at different locations on soil and water conservation were studied in order to define underlying layout principles for fish-scale pits, and to provide information for fish-scale pit site selection and effect evaluation in ecologically fragile areas. [Methods] The study was conducted at Qiansongba in the Bashang grassland area. Plots were established in shady slope, sunny slope, and river valley areas. The effects of fish-scale pits on plant biomass and root system, soil bulk density, and soil nutrient loss were determined. [Results] ① Aboveground biomass, underground biomass, rooting depth, total nitrogen (TN) and dissolved organic carbon were increased for fish-scale pits on the sunny slope, shady slope, and river valley, and the soil bulk density was decreased compared with a control area. ② The effects of fish-scale pits on shady slope, sunny slope, and river valley locations were different. Fish-scale pits on the shady slope and sunny slope significantly increased rooting depth (p<0.05) (104.19% and 42.87%, respectively). Compared with fish-scale pits at the sunny slope, fish scale pits at the shady slope also had significant effects on soil bulk density, TN content, and aboveground biomass (p<0.05) (-9.26%, 148.05%, and 136.32%, respectively). Ammonia nitrogen and nitrate nitrogen for the fish-scale pit at the river valley location were significantly higher than for the control group (p<0.05) (125.16% and 174.53%, respectively). ③ Fish-scale pit location and construction time were the most important factors influencing soil and water conservation, rather than slope position. As fish-scale pit construction time increased, aboveground biomass, underground biomass, TN content, and rooting depth increased, and soil redox potential decreased. ④ The effects of fish-scale pits on soil and water conservation in areas with severe soil erosion was more significant than in areas with less erosion. [Conclusion] Fish-scale pits produced significant soil and water conservation effects. The fish-scale pit on the shady slope had more significant soil storage and soil conservation effects than the fish-scale pit on the sunny slope. The fish-scale pit in the river valley had a greater ability to improve soil ammonia and nitrate nitrogen levels than the shady slope and sunny slope pits. Soil and water conservation was enhanced with the increase of construction time of fish-scale pits. In order to improve soil and water conservation effects, fish-scale pits should be built on shady slopes and in river valleys according to local conditions.

    • Effect of Soil Conditioner Interface Modification on Migration Characteristics of Saline-Alkali Ions in Irrigation Area of Yellow River

      2023, 43(6):98-105,114. DOI: 10.13961/j.cnki.stbctb.2023.06.013

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      Abstract:[Objective] Through the treatment of hydrophilic and hydrophobic by the conditioner, the influence of different interface characteristics of the conditioner on the soil water and salt transport law was explored, and the improvement mechanism of fly ash-based soil conditioner on saline-alkali land was revealed in order to provide scientific reference for the improvement of different types of saline-alkali land in irrigation area of the Yellow River. [Methods] Taking sodic sline soil in Ningxi Hui Autonomous Region as a case study, the spatial transport patterns of different salt ions in the soil before and after modification with the soil conditioners were investigated by soil column experiments. [Results] After the addition of unmodified conditioner, hydrophilic-modified conditioner, and hydrophobic-modified conditioner, the surface desalination rates were 79.72%, 59.91%, and 84.79%, respectively, for a sodic saline soil far greater than the values obtained without conditioner added (12.64%). Compared with the unmodified conditioner treatment group, the water content of the hydrophilic treatment group was 6.59% greater, and the total salt amount was 47.13% greater. The water content of the hydrophobic treatment group was 0.67% less, and the total salt amount was 25.22% less. The pH values were reduced from 10.5 to 8.08 and 8.71, respectively. The surface Na+ contents were reduced by 10.39% and 30.46%, and the K+ contents were reduced by 10.22% and 45.93%, respectively. [Conclusion] The interface properties of soil conditioners significantly affected water and salt transport in the soil. The hydrophobic conditioner treatment was more effective in improving saline land, and increasing the infiltration of salts with soil water is more important for saline land improvement.

    • Simulation of Soil N2O Emissions Under Different Soil Moisture Conditions by Using Mixed Dynamic Equation

      2023, 43(6):106-114. DOI: 10.13961/j.cnki.stbctb.2023.06.014

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      Abstract:[Objective] Soil moisture has an important impact on N2O emissions. This study attempted to simulate the cumulative process of soil N2O emission under different soil moisture conditions by using a mixed dynamic equation, and to analyze the influence of soil water on N2O production pathway and its variation rule in order to provide theoretical and practical guidance for reducing N2O gas emissions through improving soil management. [Methods] Soil N2O emission characteristics, the dynamics of ammonium and nitrate nitrogen content, and oxygen consumption were studied under different soil moisture conditions [40% water-holding capacity (WHC), 60% WHC, 80% WHC, 100% WHC, and flooded]. [Results] ① The N2O emission rates reached maximum values at 24 h. Emissions from the flooded treatment [3.46 μg/(kg·h)] were 54.5-178.9 times greater than from the other treatments. ② The cumulative emission of soil N2O increased with increasing incubation time, and the rapid rise stage occurred in the first 48 h for the flooded treatment. The rapid rise stage occurred in the first 96 h for other treatments. The cumulative N2O emissions for soil under the flooded treatment (44.6 μg/kg) were 67.1, 29.2, 20.8, and 10.4 times greater than under 40% WHC, 60% WHC, 80% WHC and 100% WHC, respectively, at the end of incubation. ③ Except for the coefficient of determination (R2) of 0.878 for the pseudo-second-order dynamic equation under the flooded treatment, all coefficients of determination were greater than 0.920 for all dynamic equations under all soil moisture treatments. The denitrification process accounted for 9.3%~13.2% of the N2O emissions, and the nitrification process accounted for 86.8%~90.7% of the N2O emissions at the initial 24 h of incubation. At the end of incubation (480 h), the denitrification process accounted for 37.8%~47.5% of the N2O emissions, and the nitrification process accounted for 52.5%~62.2% of the N2O emissions. [Conclusion] The higher the soil moisture content, the greater the emission of N2O, and an emission rate pulse appeared at 24 h. N2O was mainly generated by denitrification under flooded conditions. N2O was mainly generated by nitrification under the 40%~100% WHC conditions. The mixed dynamic equation was able to well simulate the cumulative emission process of soil N2O during the incubation experiment, and can be used to distinguish the amount and proportion of N2O emissions occurring by denitrification and nitrification processes. These results provide a new idea and method for studying the pathways of soil N2O production and emission. The results need to be further verified by field experiments and isotope tracing methods etc.

    • Effects of Desulfurized Gypsum Applied Combined with Polyglutamic Acid on Improving Saline Soil

      2023, 43(6):115-125. DOI: 10.13961/j.cnki.stbctb.2023.06.015

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      Abstract:[Objective] The effects of desulfurized gypsum and polyglutamic acid (γ-PGA) improves saline soil were studied in order to provide a theoretical and technical basis for improving saline soil in Northwest China. [Methods] Simulated leaching tests in soil columns and simulated growth tests in pots were used to determine the effect of combining desulfurized gypsum with γ-PGA on saline soils from the perspectives of promoting salt leaching, reducing soil salinity, lowering soil pH value, improving soil nutrient status, and promoting crop growth. [Results] The leaching tests showed that combining desulfurized gypsum with γ-PGA could further reduce soil pH value after leaching and increase Na+ leaching; reduce HCO3- and Cl- contents after leaching, but increase SO42-, Ca2+, and Mg2+ contents; and effectively reduce the sodium adsorption ratio (SAR) value of the soil. Desulfurized gypsum combined with γ-PGA significantly increased maize height, leaf area, and dry weight, with maximum dry weight at 30 days of growth increasing by 54.40% compared with the control treatment, and by 40.27% and 29.47% compared with desulfurized gypsum and γ-PGA treatments alone, respectively. In addition, soil pH value was lower and soil N, P, and K nutrient contents and soil enzyme activities were higher after the plants were harvested from the combined desulfurized gypsum and γ-PGA treatment. [Conclusion] The application of desulfurized gypsum and γ-PGA can produce complementary and synergistic effects, thereby further promoting soil ion exchange, lowering pH value, increasing soil nutrient content, and promoting crop growth.

    • Effects of Micro-topography Modification on Soil Moisture Dynamics in Cold and Arid Mining Areas of Southern Piedmont of Tianshan Mountain

      2023, 43(6):126-132. DOI: 10.13961/j.cnki.stbctb.2023.06.016

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      Abstract:[Objective] The effects of spatial and temporal dynamics of soil moisture on micro-topography modification (0-50 cm) were determined in order to provide a scientific basis and theoretical support for land reclamation and ecosystem reconstruction in cold and arid mining areas of the southern piedmont of Tianshan Mountain. [Methods] The study was conducted in the coal-mining area of Baicheng Runhua. Micro-topography changes to the overburden platform and slope of reclaimed mine land were evaluated. Soil moisture content was monitored from May to November 2022 for comparative experimental analysis. [Results] The soil moisture content of the platform storage ditch and the catchment slope transformation increased 37.03% and 25.85% respectively, and the relative enhancement effect was shown to be catchment slope > storage ditch. The water storage ditch and the catchment slope modification methods improved the temporal stability of soil moisture, and their relative effects were found to be water storage ditch > catchment slope. The soil moisture contents of the side slope reverse-slope terraces and the fish-scale pit transformation increased by 6.48% and 13.22%, respectively, and the relative enhancement effect was shown to be fish-scale pit> reverse-slope terrace. The fish-scale pit transformation method improved the temporal stability of soil moisture, and the reverse-slope terrace transformation method reduced the temporal stability of soil moisture. [Conclusion] Under the two topographical conditions of platform and side slope, the transformation of the catchment slope was more conducive to the ecological management of the damaged mine platform, and the transformation of the fish-scale pit was more conducive to the ecological management of the damaged mine slope.

    • Water Conservation Function of Artificial Forests in Kubuqi Desert

      2023, 43(6):133-141. DOI: 10.13961/j.cnki.stbctb.2023.06.017

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      Abstract:[Objective] Research was conducted on understory litter and soil hydrological function for artificial forests in the forest protection station in the eastern section of the Kubuqi Desert. The comprehensive weight value of various indicators of the artificial forests in this area were scientifically calculated, and the hydrological effect and water conservation function of artificial forest litter and soil were determined in order to provide theoretical guidance for the directional tending of returning sand to forest in this area and related sandy areas. [Methods] Five common types of artificial shelterbelts were used in the Ordos afforestation station in the Kubuqi Desert. The water-holding capacity of litter and soil were determined using field measurements and the indoor immersion method, and the water conservation function of each forest was assessed using a combination of the analytic hierarchy process (AHP) and the entropy-weight method (EWM). [Results] ① The litter thickness in each stand ranged from 6.56 to 22.20 mm, and the litter accumulation ranged from 1.44 to 13.62 t/hm2. Interception capacity for the different forest stands followed the order of Salix matsudana-Populus×euramericana mixed forest > Populus×euramericana forest > Pinus sylvestris forest >3-year S. matsudana forest >8-year S. matsudana forest. ② The maximum water-holding depth of litter was linearly related to the dry mass, and the maximum storage was about 1.36~2.04 L of precipitation in each stand. These results showed that the maximum water-holding capacity of the litter depended mainly on the dry weight of the litter, while related factors such as tree species, age, and meteorology indirectly affected the water-holding capacity by influencing the dry weight of the litter. ③ Logarithmic and power functions provided good representations of the dynamic water-holding capacity and dynamic water uptake of litter, respectively. ④ The saturated water-holding rate, capillary water-holding rate, and total porosity basically showed decreasing trends as soil depth increased, and soil bulk density showed an increasing trend. ⑤ The S. matsudana-Populus×euramericana mixed forest exhibited a higher water conservation function than the other forests, the Populus×euramericana and Pinus sylvestris forests had similar water conservation functions, and the S. matsudana forests had the lowest water conservation functions. [Conclusion] Construction of future artificial shelterbelts in desert regions should prioritize the cultivation of mixed forests, and a more scientific plan for the return of sand to forests should be developed by considering differences in the water conservation function between tree species.

    • >Water Conservation Monitoring and Application Technology
    • Slope Rill Erosion and Morphological Evolution Based on UAV Nap-of-the-object Photogrammetry

      2023, 43(6):142-147. DOI: 10.13961/j.cnki.stbctb.20230614.001

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      Abstract:[Objective] This study was conducted to determine a rill erosion technology having high efficiency, high accuracy and strong adaptability, and overcome deficiencies associated with traditional measurement methods (low efficiency, high cost, poor applicability, etc.) in order to provide new ideas and technical means for the evolution of slope rill erosion and quantitative research. [Methods] UAV technology was used to acquire high-resolution images and models of rill development on slopes under six consecutive simulated rainfall events by use of nap-of-the-object photogrammetry. The feasibility of slope rill erosion and morphological evolution was quantitatively evaluated by positioning accuracy, model accuracy, and erosion simulation. [Results] ① The root mean square error (RMSE) of geographic registration of the 3D real scene model was 1.5 cm. The image control point plane RMSE was 0.42 cm. The elevation RMSE was 0.88 cm. The model details and texture were clear, with millimeter-level resolution. ② The multi-phase model clearly described five stages of rill development:raindrop splash erosion, sheet erosion, small waterdrop erosion, intermittent rill erosion, and continuous rill erosion. The average width, depth, and density of rills on the slope surface developed from the initial values of 1.25 cm, 0.82 cm, and 0.05 to the final values of 3.27 cm, 4.75 cm and 0.23, respectively. The maximum trench length was 236 cm and the maximum trench depth was 14.23 cm. ③ As rainfall duration increased, the simulated values of soil erosion in rills were close to the real values and tended to become stable, with an average error of less than 10%. [Conclusion] UAV nap-of-the-object photogrammetry can better reflect rill development and evolution, and has significant advantages over traditional measurement methods in efficiency and convenience.

    • Comprehensive Benefits Evaluation of Desert Highway Sand Control Engineering Based on Matter-element Extension Model with Variable Weight

      2023, 43(6):148-154,173. DOI: 10.13961/j.cnki.stbctb.20231115.001

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      Abstract:[Objective] The comprehensive benefits of desert highway sand control engineering were evaluated in order to provide a scientific reference for research to evaluate sand control engineering of highways in wind-blown sand areas, and for subsequent work with respect to operation and maintenance. [Methods] The sand control engineering of desert section of the Wuhai-Maqin Highway was taking as a case study, based on an analysis of the influencing factors of the comprehensive benefits of desert highway sand control projects, a comprehensive benefits evaluation indicator system for highway sand control engineering was constructed from three aspects:engineering benefits, economic benefits, and environmental benefits. A matter-element extension model with variable weight was constructed. Fixed weights were then corrected using variable-weighting theory to reflect the effect of fluctuations in indicator values on indicator weights. The indicators that had a significant impact on the comprehensive benefits were also identified through sensitivity analysis. Finally, the model was applied to sand control engineering in the desert section of the Wuhai-Maqin highway. [Results] The comprehensive benefits of sand control engineering in the desert section of the Wuhai-Maqin highway were in the "relatively good" benefit level, but they strongly trended towards the "medium" benefit level. Compared with the traditional fixed-weight method, the benefits were more in line with engineering reality. Among the many indicators, the protective effect, breakage degree, construction quality, and effects of vegetation environment had the most significant impacts on the evaluation results. [Conclusion] To further improve the comprehensive benefit level of sand control projects in the desert section of the Wuhai-Maqin highway, the changing trend of these indicators should be focused on in the later stages of operation and maintenance, and maintenance work should be targeted to ensure maximum comprehensive benefits.

    • Impacts of a New Round of Returning Farmland to Forests and Grasslands Project on Land Use Efficiency—Empirical Study in Yellow River Basin

      2023, 43(6):155-164. DOI: 10.13961/j.cnki.stbctb.2023.06.020

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      Abstract:[Objective] The impacts mechanism and policy effectiveness of the implementation of a new round of the returning farmland to forests and grasslands project on land use efficiency in the Yellow River basin were analyzed in order to provide a theoretical reference for understanding land use efficiency and promoting a new round of the returning farmland to forests and grasslands project. [Methods] The implementation of a new round of the returning farmland to forests and grasslands project in the Yellow River basin was used as a natural experiment. Land use efficiency was measured by the Super-Window-DEA model including unexpected output indicators. The double difference model and the mediation effect model were used to analyze the policy effectiveness and transmission pathways. [Results] ① Land use efficiency of 69 cities in the Yellow River basin slightly decreased from 2009 to 2020. Land use efficiencies for the upstream (0.546 5) and downstream (0.419 9) regions were higher than for the midstream region (0.279 5). ② The new round of the returning farmland to forests and grasslands project significantly suppressed the increase in land use efficiency, and the negative effects of policies were heterogeneous. Meanwhile economic development increased land use efficiency and population density decreased land use efficiency. ③ The proportion of arable land and fiscal expenditures were mediating variables for the impact of the new round of the returning farmland to forests and grasslands project on land use efficiency. Moreover, the proportion of farm land was a partial mediator. [Conclusion] The results of this study suggested increasing the implementation of returning farmland to forests and grasslands project on land with poor fertility and scarce labor input, encouraging cities in the Yellow River basin to open up wasteland and implement green policies for unused land. Additionally ecological compensation between the upper, middle, and lower reaches of the Yellow River basin and cities within the basin should be carried out. Full use should be made of credit funds to lead into ecological industrialization development. Upgrading of green industries should be promoted and efforts should be encouraged to develop a new model of ecological compensation for the project of returning farmland to forests and grasslands.

    • Farmers' and Herdsmen' Sustainable Livelihood Capital and Livelihood Strategy in Enclosed Reserves of Desertified Land—Taking Four Enclosed Reserves in Gansu Province as an Example

      2023, 43(6):165-173. DOI: 10.13961/j.cnki.stbctb.2023.06.021

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      Abstract:[Objective] The relationship between farming and herding households' livelihood capital and livelihood strategies was studied, and the spatial differences of farming and herding households' livelihood capital and the transformation between livelihood strategies were analyzed in order to provide a theoretical basis for reducing farming and herding households' livelihood vulnerability and ultimately achieving sustainable development. [Methods] Starting from the theoretical framework of sustainable livelihood analysis, a household questionnaire survey was used to analyze the key factors of livelihood capital and livelihood strategy transformation for farming and herding households in the national sandy land enclosed reserves in Maqu, Minqin, Shandan County, and Liangzhou District in Gansu Province, which were approved to be established in 2017, by combining a Logistic regression model and one-way analysis of variance (ANOVA). [Results] Financial capital was the most abundant form of livelihood capital, while natural capital was the least abundant form of livelihood capital for the farmers and herdsmen in the enclosed reserves of desertified land. There were significant differences in the distribution of livelihood capital among farmers and herdsmen with different livelihood strategies, and the livelihood capital of non-agricultural farmers and herdsmen was better than that of purely farming households. Cultivated (or grassland) area, cultivated (or grassland) quality, and production tools had significant positive effects on the choice of purely farming households. The size of the family labor force, the education level and the total household income had a significant negative impact on the choice of purely farming livelihood strategy. [Conclusion] The following countermesures should be promoted in the future. Those are increasing the publicity of ecological environmental protection in enclosed protected areas, strengthening the awareness of ecological protection among farmers and herdsmen, accelerating the development of agricultural mechanization, and encouraging the transformation of the remaining labor force to non-agricultural industries, thereby achieving diversification of livelihoods.

    • Evaluation of Water Resource Vulnerability in Changsha City Based on VSD and Cloud Matter-element Model, and Diagnosis of Obstacle Factors

      2023, 43(6):174-184,247. DOI: 10.13961/j.cnki.stbctb.2023.06.022

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      Abstract:[Objective] The vulnerability of water resources in Changsha City was evaluated based on the connotation of vulnerability and its obstacles factors were identified, in order to provide a theoretical basis for the formulation of water resources management and control strategies in Changsha City, Hunan Province. [Methods] A comprehensive evaluation index system was established based on the vulnerability scoping diagram (VSD) conceptual framework. Game theory was used to determine the combined weight. The cloud matter-element model was used to comprehensively evaluate the vulnerability of water resources in Changsha City from 2014 to 2020. The obstacle degree model was used to diagnose and analyze the obstacle factors affecting the vulnerability of water resources in the city. [Results] ① From 2014 to 2020, the vulnerability of water resources in Changsha City showed a decreasing trend, from a medium level of vulnerability to a slight level of vulnerability; ② The evolution trends of vulnerability at each criterion level were different, the vulnerability of the exposure dimension was consistently high, the vulnerability of the sensitivity dimension was unstable, and the vulnerability of the adaptability dimension showed a clear downward trend; ③ The obstacle degree for the exposure criterion level was the highest, and per capita water resources, per capita daily water consumption, total industrial wastewater discharge, water storage capacity of the upper-type reservoir, and annual precipitation were the main obstacle factors that restricted the decline of water resource vulnerability in Changsha City. [Conclusion] In order to further reduce the level of vulnerability of water resources in Changsha City, the relationship between socio-economic development and the development and utilization of water resources should be coordinated in the future to reduce the pressure of human activities on the water resources system, and at the same time, the supervision and management of water conservation should be further strengthened, the investment in the construction of reservoirs should be intensified, and the utilization of recycled water and rainwater resources should be promoted.

    • Ecological Value of Multi-scale Cultivated Land Protection and Compensation Standards in Watersheds

      2023, 43(6):185-192,199. DOI: 10.13961/j.cnki.stbctb.2023.06.023

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      Abstract:[Objective] The ecological value of cultivated land and compensation standards at multiple scales in a watershed was measured and analyzed in order to provide scientific reference for improving the compensation mechanism for cultivated land protection and promoting coordinated regional development. [Methods] The Liaohe River basin in Jilin Province was taking as an example, and used the equivalent sub-method, the market substitution method, and a landscape pattern index were used to establish a multi-scale cultivated land ecological value accounting system for the basin. The quantity and spatial allocation of cultivated land, differences in cultivated land quality, and the negative ecological externality of cultivated land were taken into account. On this basis, the cultivated land ecological compensation standard was formulated. [Results] ① Cultivated land had very important ecological values in the Liaohe River basin of Jilin Province, and the ecological values had significant spatial differences and scale-dependent effects. ② In 2020, the ecological value of cultivated land in the watershed was 20 502.78 yuan/ha, and the ecological value of cultivated land in each district and county had values between 4 261.97 and 16 873.59 yuan/ha, with values in the northwest region being higher than in the southeast region. ③ The compensation standard for cultivated land protection in the watershed was 4 319.36 yuan/ha, and the compensation standard of each district and county ranged from 814.68 to 3 471.85 yuan/ha. [Conclusion] For different spatial scales, differentiated ecological compensation standards and programs for cultivated land protection should be established, taking into account the ecological value of cultivated land and regional realities.

    • Ecological Protection Effects Provided by Sand Barriers in a Grassland Mining Area

      2023, 43(6):193-199. DOI: 10.13961/j.cnki.stbctb.2023.06.024

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      Abstract:[Objective] The wind protection effectiveness of different sand barriers and their effects on surface soil particle size composition, soil nutrients and vegetation growth werer studied in order to provide a theoretical basis for the optimal selection of sand barriers for dump slopes in grassland mining areas. [Methods] Reed curtain sand barriers and Salix psammophila sand barriers having different specifications (0.5 m×0.5 m, 1.0 m×1.0 m, and 1.5 m×1.5 m) were set up on a dump slope in the study area. Wind protection effectiveness, soil particle size composition, soil nutrients, and vegetation growth were used to evaluate the ecological protection effects of different sand barriers on the dump slope. [Results] ① The sand barrier reduced the surface wind speed, and the wind protection effectiveness of the 0.5 m×0.5 m reed curtain sand barrier was the highest at the height of 10 cm (84.30% efficiency). The overall wind protection effectiveness of the sand barriers followed the order of 0.5 m×0.5 m > 1.0 m×1.0 m > 1.5 m×1.5 m. ② The content of silt, very fine sand, and fine sand in the surface soil of the 0.5 m×0.5 m reed curtain sand barriers accounted for 58.28% of the total particle size fractions. Soil moisture content, organic matter, total nitrogen, and total phosphorus content were the highest for this treatment, and were 29.72%, 29.69%, 22.22% and 83.33%, respectively, greater than the values observed for the control treatment. The total potassium content of the soil with the 0.5 m×0.5 m S. psammophila sand barrier was the highest (8.80% greater than observed for the soil from the control treatment. ③ The placement of sand barriers promoted the establishment of herbaceous plants, resulting in an increase in the number of plant species in the sand barrier plots, and a greater number of plant species in the small-size sand barriers than in the large-size sand barriers. [Conclusion] Sand barrier construction is beneficial to the ecological restoration of dump slopes. These results suggest that the construction of 0.5 m×0.5 m reed curtain sand barriers during the early restoration of dumps in grassland mining areas.

    • Sustainable Utilization and Obstacle Factors of Water Resource in Jiangxi Province

      2023, 43(6):200-208. DOI: 10.13961/j.cnki.stbctb.2023.06.025

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      Abstract:[Objective] The sustainable water resource utilization in Jiangxi Province were evaluated and its main obstacles were analyzed in order to provide theoretical references for optimizing water resource governance policy. [Methods] The DPSIR model was used as a framework to construct a sustainable water resource utilization evaluation index system (including 29 secondary indicators) for Jiangxi Province. The trend of changes in the level of sustainable water resources utilization in Jiangxi Province was evaluated using the entropy-weight TOPSIS method, and the main obstacle factors hindering the sustainable water resources utilization were identified using the obstacle degree diagnosis method. [Results] The sustainable water resource utilization level in Jiangxi Province from 2011 to 2020 (except for 2013 and 2018) increased with increasing years. The average sustainable water resource utilization level after 2015 (0.375 8) was 10.15% greater than before 2015 (0.340 8). The main obstacle factors included the treatment capacity of wastewater treatment facilities, total water resources, surface water storage capacity, number of wastewater treatment facilities, and per capita GDP. [Conclusion] Insufficient investment in governance and low management efficiency due to low economic development and science and technology level continue to hinder the sustainable use of water resources in Jiangxi Province. It is suggested that water resource governance policies should be optimized by adhering to the measures defined in "one policy for one river", focusing on innovative technology, upgrading industrial structure, and establishing policy communities.

    • Construction of Ecological Security Pattern and Identification of Key Regions Based on Ecological Assessment and Circuit Theory—A Case Study in Anhui Province

      2023, 43(6):209-216,226. DOI: 10.13961/j.cnki.stbctb.2023.06.026

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      Abstract:[Objective] The ecological security pattern of Anhui Province was constructed and the key areas of ecological restoration were identified in order to build an ecological basis for urban development, and to provide a scientific basis for the territorial ecological restoration of Anhui Province. [Methods] The InVEST model and the MCR model were used to evaluate and identify ecological source areas from the supply side and the internal response side of the ecosystem. The resistance surface was modified by nighttime light data. The ecological security pattern for Anhui Province was constructed based on the circuit theory. The ecological pinch points and ecological barrier points were identified, and differentiated restoration and maintenance measures were proposed according to spatial differentiation and terrain characteristics. [Results] ① There were 53 ecological source areas in Anhui Province, with a total area of 4.22×104 km2, accounting for 30.5% of the total area of Anhui Province. The southern source areas were concentrated and had high ecological value, while the northern source areas was scattered and had low ecological value. ② Ninety-five ecological corridors were constructed. Based on landscape connectivity analysis, 68 key corridors, 26 important corridors, and one general corridor were selected. ③ There were 119 ecological pinch points with an area of 412.45 km2, and 46 ecological barrier points with an area of 423.20 km2. ④ Ecological pinch points and scattered ecological barrier points were maintained by nature, and artificial restoration and natural restoration of large ecological obstacles were implemented simultaneously. [Conclusion] The ecological security pattern constructed with the help of ecological assessment and circuit theory was more in line with the actual process of species movement, and can effectively identify the key areas of ecological restoration and their distribution characteristics.

    • Rapid Identification and Extraction of Anthropogenically Disturbed Regions Resulting from Production and Construction Projects in Hubei Province from 2017 to 2021

      2023, 43(6):217-226. DOI: 10.13961/j.cnki.stbctb.2023.06.027

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      Abstract:[Objective] This study attempted to identify and extract anthropogenic disturbance areas resulting from production and construction projects in Hubei Province from 2017 to 2021. Spatiotemporal feature analysis of the classification results was also conducted in order to provide theoretical support and methodological references for the extraction of anthropogenic disturbance areas, and to address soil and water erosion issues. [Methods] The study was conducted in Hubei Province because of its diverse range of anthropogenic disturbance types from production and construction projects. We used the Google Earth Engine (GEE) platform to access Sentinel-2 time-series data. We investigated the optimal combinations of classification features and parameters using a 1 995 dataset. To tackle the issue of differentiating impermeable layers from croplands within anthropogenic disturbance areas caused by production and construction projects, we employed a random forest model for the annual identification and extraction of such areas in Hubei Province from 2017 to 2021. [Results] ① The optimal feature band combination for identifying and extracting anthropogenic disturbance areas from production and construction projects included the red-edge band, green-edge band, blue-edge band, near-infrared band, NDVI, NDWI, NDBI, RRI, dNDVI, contrast, and entropy. ② Overall, the classification accuracy for the years 2017 to 2021 consistently exceeded 93.00%, with kappa coefficients consistently above 0.92, affirming the method was feasibility for extracting anthropogenic disturbance areas due to production and construction projects. ③ The total area of anthropogenic disturbance land parcels in Hubei Province exhibited a pattern characterized as "increase-decrease-increase" from 2017 to 2021, with an anomalous decrease in 2020. [Conclusion] The proposed method demonstrated substantial potential for the rapid identification of large-scale, diverse anthropogenic disturbance areas resulting from production and construction projects. The resulting high-precision, long-term spatial dataset can provide valuable support for subsequent research endeavors related to this topic.

    • >Soil and Water Conservation Monitoring and Applied Technology
    • Importance Analysis of Vegetation Change Factors in East Africa Based on Machine Learning

      2023, 43(6):227-236. DOI: 10.13961/j.cnki.stbctb.2023.06.028

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      Abstract:[Objective] A factor importance analysis of vegetation changes in East Africa based on different machine learning algorithms was conducted to measure the accuracy and applicability of the different algorithms in order to provide a scientific basis for protecting, restoring, and promoting sustainable forest management and comprehensive prevention and control of soil erosion. [Methods] Changes in normalized difference vegetation index (NDVI) for nine countries in East Africa from 2001 to 2020 were determined. The independent treatment variables were two climatic factors and five human activity factors affecting vegetation changes in East Africa. Six machine learning algorithms were used to establish NDVI prediction models:random forest (RF), BP neural networks (BP), support vector machines (SVM), genetic algorithm (GA), radial basis function (RBF), and convolutional neural networks (CNN). Coefficient of determination (R2), mean absolute error (MAE), and mean relative error (MRE) were used as error indicators to evaluate the potential of the six machine learning algorithms for predicting NDVI changes. Based on the optimal model (RF), the importance of the selected seven factors was determined. [Results] The accuracy verification results showed that the regression accuracy of the CNN algorithm was the worst for the full factor case in the study area. After deleting an algorithm with poor comprehensive performance in each round of testing, the model established by the RF algorithm had the highest regression accuracy for NDVI change analysis in East Africa. The importance of different factor variables to NDVI change based on RF showed that annual precipitation, N2O emission, CH4 emission, and livestock number had the greatest influence on the results of the NDVI change regression. [Conclusion] RF had a comparative advantage for NDVI simulation in East Africa. Precipitation was the most important climatic factor affecting vegetation changes. At the same time, greenhouse gas emissions also had an important impact on vegetation changes in East Africa. East African countries should raise awareness and understanding of the interdependence of vegetation changes on climate, environment, socio-economic conditions, and political systems, and develop appropriate policies to promote sustainable forest management and to combat desertification.

    • >Water Conservation Monitoring and Application Technology
    • Construction and Evaluation of an Ecological Network for Dongguan City Based on Urban Big Data POIs and Circuit Theory

      2023, 43(6):237-247. DOI: 10.13961/j.cnki.stbctb.2023.06.029

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      Abstract:[Objective] The ecological network pattern of Dongguan City, Guangdong Province were constructed and the importance of ecological corridors was evaluated to identify ecological pinch points and barriers, determine the key areas for ecological protection and restoration, and propose corresponding ecological restoration strategies, in order to provide a scientific basis for the formulation and adjustment of subsequent related land and spatial planning and relevant special plans. [Methods] Based on the traditional research approach of "identifying ecological sources-establishing resistance surfaces-extracting ecological corridors," urban big data points of interest (POIs) were introduced to address the problem of insufficient accuracy in ecological source identification and resistance surface construction. Circuit theory was used to identify ecological corridors, pinch points, and barriers to construct the overall ecological network pattern of Dongguan City. [Results] ① A total of 29 ecological sources were identified, accounting for 20.45% of the study area. The main ecological sources were located in the southern part of Dongguan City; ② A total of 74 ecological corridors were generated, of which 12 were potential ecological corridors. The water towns and urban edge areas need to be focused on and protected. [Conclusion] The southern part of Dongguan City was found to have better ecological conditions where the ecological source areas were concentrated. However, there were many ecological pinch points and barriers in the urban edge areas and the northern water town area that require priority for ecological restoration and maintenance.

    • Research Progress and Prospect of Slope Greening in China—Bibliometric Analysis Based on CiteSpace and VOSviewer

      2023, 43(6):248-255. DOI: 10.13961/j.cnki.stbctb.2023.06.030

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      Abstract:[Objective] The current status and hot trends of slope greening research were studied in order to provide theoretical support and references for subsequent research. [Methods] Professional bibliometric tools CiteSpace and VOSviewer were used to visualize and analyze slope greening research literature indexed by the China National Knowledge Infrastructure (CNKI) database. The main indicators included publication volume, high-frequency keywords, keyword co-occurrence clusters, and burst keywords. The research hotspots and changes in research trends were discussed from three aspects:mechanisms of slope root fixation of soil, selection and configuration of slope plants, and application of engineering greening technology. [Results] There has been a good trend of publishing scientific research results in the field of slope greening in China. Research institutions were mostly higher education institutions (colleges and universities) with programs in the fields of agriculture, forestry, science, and engineering. As a multidisciplinary and comprehensive application technology, slope greening has a very necessary role to play in industry associations. [Conclusion] At present, the variation pattern of slope stability is an important research direction. Numerical simulation technology is expected to play a greater role in the study of slope stability. Plant screening research has focused on the ecological adaptability of plants, which can strengthen future investigations and breeding efforts related to plants adapted to slope protection in the region. Determining the factors influencing plant diversity changes can contribute to the sustainability of plant configuration. Spraying was found to be the most widely used greening technology. The topics of erosion resistance and stability of substrate materials were research hotspots. In the future, it will be necessary to start with the standardization of terminology, construction methods, equipment, and materials so as to gradually establish a standard system for spraying and greening technology applicable to conditions found in China.

    • >Comprehensive Research
    • Welfare Effect of Farmers' Participation in Soil Conservation: Concept, Connotation and Evaluation Index Framework

      2023, 43(6):256-262,293. DOI: 10.13961/j.cnki.stbctb.2023.06.031

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      Abstract:[Objective] A concept, connotation and evaluation index framework of welfare effect of farmers' participation in soil conservation practices was systematically reviewed, which could provide a scientifical basis for comprehensive evaluation of the welfare effect of soil conservation. [Methods] By assembling existing publications and relevant standard documents, the concept and connotation of welfare effect of soil conservation were formulated, and the logical relationship between soil conservation benefits and soil conservation welfare effect. Furthermore, the evaluation scale of the welfare effect of soil conservation was sorted out, and an evaluation index framework for the welfare effect was proposed. [Results] The welfare effect of soil conservation had intrinsic characteristics of clear evaluation objects, monetizable value, high correlation with participation degree, individual difference, and group consistency. It is also considered to be deepened and expanded understandings of the benefits of soil conservation, and this relationship is inter-contained and inter-included. Evaluation of the soil conservation welfare effect should be based on a comprehensive evaluation of soil conservation benefits, and its index framework should include multiple elements such as economic welfare, social welfare, and ecological welfare. [Conclusion] The welfare effect of farmers' participation in soil and water conservation has not yet gained enough attention currently. The evaluation of the welfare effect of soil and water conservation only focuses on policy-based soil and water conservation projects, and its evaluation indicators and methods have not formed a unified understanding. It is necessary to further study the theory and methodology of the welfare effect of soil and water conservation, thereby providing references for decision-making in the construction of soil and water conservation in the new era.

    • Spatial-temporal Evolution and Influencing Factors of Dominant Marginalization of Cultivated Land in Guizhou Province Based on Land Use Change

      2023, 43(6):263-271. DOI: 10.13961/j.cnki.stbctb.2023.06.032

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      Abstract:[Objective] The spatial-temporal evolution pattern and influencing factors of the dominant marginalization of cultivated land in Guizhou Province from 2010 to 2020 were analyzed in order to provide policy guidance for the intensive use of cultivated land in mountainous areas. [Methods] A land use transfer matrix, spatial autocorrelation model, and geographic detector were comprehensively used to systematically determine the overall situation, spatial agglomeration effect, and related influencing factors of the dominant marginalization of cultivated land in Guizhou Province. [Results] ① The dominant marginalization rate of cultivated land in Guizhou Province during 2010-2020 was 10.20%. In general, natural marginalization was the main factor, but economic marginalization developed rapidly. With economic and social development, the dominant marginalization rate of cultivated land continued to accelerate. ② The dominant marginalization level of cultivated land in Guizhou Province during 2010-2020 generally showed a pattern characterized as "higher in the south, lower in the north, and gradually expanding to the west and southeast". During 2010-2015, the pattern was characterized as "higher in the south and lower in the north". Duging 2015-2020, the pattern was "higher in the middle surrounded by lower". ③ Per capita cultivated land area, urbanization rate, vegetation coverage, and other factors were the main influencing factors of the spatial difference in the marginalization of cultivated land in Guizhou Province. [Conclusion] The temporal and spatial evolution of the dominant marginalization of cultivated land in Guizhou Province exhibited significant differences. Natural conditions such as elevation, slope, and vegetation coverage were the basic characteristics of the temporal and spatial differences in the dominant marginalization of cultivated land. Socio-economic factors, such as per capita cultivated land area, urbanization rate, GDP density, etc. were the main driving force behind the rapid development rate of the dominant marginalization of cultivated land.

    • Supply and Demand of Multi-scale Ecosystem Services and Their Influencing Factors in Hu'nan Province

      2023, 43(6):272-281. DOI: 10.13961/j.cnki.stbctb.2023.06.033

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      Abstract:[Objective] The distribution pattern of ecosystem service supply and demand and their main driving factors were analyzed in order to provide a scientific reference for regional ecological protection practices and ecological environmental improvement. [Methods] The supply and demand of five ecosystem services in Hu'nan Province from 2000 to 2020 were assessed, including food production, carbon sequestration, water conservation, soil conservation, and habitat quality by use of the InVEST model, ArcGIS, and other tools to analyze their spatial and temporal evolution patterns and spatial matching relationships, and to determine the driving factors affecting the supply-demand ratios of ecosystem services at the grid scale and county scale using an optimal parameter geodetector model. [Results] ① The total supply of ecosystem services in Hu'nan Province was greater than the total demand. The supply of carbon sequestration services and habitat quality services as well as the demand for water conservation services decreased over time, while the supply and demand of other ecosystem services increased. ② The distribution of supply and demand of various ecosystem services in Hu'nan Province, the clustering characteristics of supply-demand ratios, and the spatial heterogeneity of the spatial matching of supply and demand were obvious. ③ There were some differences in the dominant factors of ecosystem service supply-demand ratios between the two scales, and the influence of socio-economic factors was more significant at the county scale than at the grid scale. The interaction between land use factors and other factors explained the spatial variation of ecosystem service supply-demand ratios more strongly. [Conclusion] The contradiction between supply and demand of ecosystem services at different scales was exceptional, and government agencies at all levels should develop more precise ecological management practices in the future, and use them as a basis to promote the rational use of regional land and to ultimately achieve the goal of regional green development.

    • Coupling and Coordination Relationship Between New Urbanization, Economic Development, and Ecological Water Environment in Huaihe River Economic Belt, and Their Driving Factors

      2023, 43(6):282-293. DOI: 10.13961/j.cnki.stbctb.2023.06.034

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      Abstract:[Objective] The coupling coordination relationship and driving factors between new urbanization, economic development, and the ecological water environment in the Huaihe River economic belt were analyzed in order to provide a scientific reference for ecological construction and environmental protection in the region. [Methods] An evaluation index system was established for the Huaihe River economic belt. A coupling model and a panel data model were used to analyze the spatio-temporal evolution characteristics and influencing factors of the coupling coordination degree among the three systems from 2010 to 2020. [Results] ① From 2010 to 2020, the comprehensive levels of new urbanization, economic development, and the ecological water environment in the Huaihe River economic belt showed an upward trend, and the coupling coordination degree of the three systems was at a high level. The level of coupling coordination degree continued to increase, and the change trends of the three systems in the eastern, northern, and central-western regions converged, similar to the overall trend. ② Factors such as opening up to the outside world, economic development, industrial structure, water use efficiency, government, science and technology, population, and education had different degrees of coupling coordination for the entire region and for the three sub-regions. [Conclusion] The Huaihe River economic belt should simultaneously focus on improving the quality of urbanization, promoting high-quality economic development, and protecting the ecological water environment while fully utilizing positive factors, reducing the impact of negative factors, and achieving the high-quality coupling coordination development of the three systems.

    • Spatial-temporal Variation and Driving Forces of Water Yield in Harbin City

      2023, 43(6):294-303. DOI: 10.13961/j.cnki.stbctb.20230814.001

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      Abstract:[Objective] The spatial-temporal variation characteristics of water yield services in Harbin City, Heilongjiang Province from 2000 to 2020 were determined, and the driving mechanism of the spatial-temporal differentiation characteristics of Harbin City's water yield was analyzed in order to provide a scientific basis for the management and sustainable development of water resources in Harbin City. [Methods] The study was conducted in Harbin City, a typical cold land city. The spatial-temporal variation characteristics of water yield in 2000, 2010, and 2020 were analyzed based on the InVEST model's water yield module, and the spatial and temporal evolution of water yield services in Harbin City was determined by using a parameter optimal geographic detector. [Results] ① The water output of Harbin City from 2000 to 2020 increased from 9.68×109 m3 in 2000 to 2.23×1010 m3 in 2020. The spatial distribution pattern of water yield in different years was basically similar. The overall spatial distribution of water yield was characterized as "higher in the east and lower in the west". ② There was a strong positive spatial correlation in the distribution of water yield in the study area, with the main types being low-low aggregation and high-high aggregation. The proportions of the two areas relative to the city's total area showed a downward trend from 2000 to 2020. ③ The influence of each driving factor on water yield exhibited obvious spatial heterogeneity. Actual evapotranspiration and land use type were the main driving factors of the economic quality development zones. In the nature-dominated ecological barrier area, the comprehensive driving forces of actual evapotranspiration and land use type were far less than in the economic quality development area. [Conclusion] Water yield assessment was closely related to ecosystem services and ecological product value, and serves as the basis of water conservation research. The temporal and spatial changes of water production in Harbin City from 2000 to 2020 were significant, and meteorological and land use factors were the main driving factors.

    • Spatial-temporal Variation of Vegetation Coverage and Its Influencing Factors in Binchang Mining Area from 1986 to 2021

      2023, 43(6):304-310,323. DOI: 10.13961/j.cnki.stbctb.2023.06.036

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      Abstract:[Objective] The change characteristics and influencing factors of vegetation coverage and its spatial distribution in the Binchang mining area were analyzed, and the ecological status of the mining area was evaluated in order to provide a scientific reference and theoretical basis for reclamation and ecological restoration of the mining area. [Methods] Landsat Surface Reflectance Tier 1 data (30 m resolution) from 1986 to 2021 were obtained from the Google Earth Engine cloud platform. Based on a pixel binary model, the trend analysis method and F-test were used to quantitatively analyze the temporal and spatial variation of vegetation coverage in the Binchang mining area over many years. Geodetector was used to analyze the spatial heterogeneity of vegetation coverage. [Results] ① Vegetation coverage in the Binchang mining area increased from 1986 to 2021, and the overall growth trend was good (average growth rate of 0.64%/a). The average multi-year vegetation coverage in the study area was relatively high, with the area of medium coverage and greater accounting for 87.14% of the total area. The spatial distribution was characterized as "higher in the southeast and lower in the northwest". ② In terms of the change trend of vegetation coverage, the study area was dominated by significantly improved areas, accounting for 56.65% of the total area. However, there were still some areas with significant vegetation degradation, mainly concentrated in the area near urban river roads. ③ The factors influencing vegetation coverage followed the order of slope > elevation > annual precipitation > GDP> population density > annual average temperature > vegetation type > soil type. The interaction between slope and annual precipitation had the strongest influence on the spatial heterogeneity of vegetation coverage. [Conclusion] From 1986 to 2021, the vegetation coverage in the Binchang mining area was good, showing a significant growth trend as a whole, and the vegetation improvement was obvious. The dominant factor affecting the spatial heterogeneity of vegetation coverage in the study area was slope.

    • Spatiotemporal Evolution and Coupling Coordination of Socio-economic Level and Ecological Resilience in Fuzhou Metropolitan Area

      2023, 43(6):311-323. DOI: 10.13961/j.cnki.stbctb.2023.06.037

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      Abstract:[Objective] The coordinated state of socio-economic level (SEL) and ecological resilience (ER) in the Fuzhou metropolitan area (FMA) and its development trend were analyzed in order to provide regulatory suggestions and theoretical references for high-quality and sustainable development of this metropolitan area. [Methods] Data were obtained for 27 county cities in FMA, and a three-dimensional ecological resilience evaluation model based on the "resistance-recovery-adaptability" characteristics of resilience was constructed. A universal social and economic level evaluation index system was also constructed. The entropy weight method, coupling coordination degree model, kernel density model, scissors difference method, and gravity center migration model were used to determine the temporal and spatial evolution trends of SEL, ER, and coupling and coordination level of FMA. The main factors affecting the coordinated development were determined by Pearson correlation analysis. [Results] ① The mean value of SEL for FMA increased from 0.181 2 to 0.320 8. The spatially high SEL areas were distributed as "one core and three centers" with FMA as the core. ② The mean value of ecological environmental resistance (ER) decreased from 0.429 4 to 0.349 4, and the high ER areas were mainly concentrated in the inland mountainous areas such as "Yanping-Gutian", while the low ER areas were located in the coastal area of "Mawei-Meizhou Island", and formed a resilience "depression" in and around FMA. ER and its subsystems exhibited strong positive autocorrelation in space. ③ The mean value of coupling coordination degree steadily increased from 0.51 to 0.56. The speed of development in terms of the SEL and ER of counties tended to be balanced, and the scissor angle difference generally decreased. The center of gravity of coordinated development moved to the central part of FMA, and the number of counties entering a type of coordinated development increased significantly. The main factors hindering the coupled coordination were the risk resistance index, per capita GDP, and the number of hospital beds per thousand people. [Conclusion] The SEL and ER of FMA showed a trend of "misaligned" development in space-time, and the coupling and coordination level of both still has much room for improvement.

    • GIS-based Study of Ecological Water Requirement of Vegetation in Inner Mongolia Autonomous Region

      2023, 43(6):324-335,401. DOI: 10.13961/j.cnki.stbctb.2023.06.038

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      Abstract:[Objective] The ecological water requirement (EWR) of vegetation in different typical zones for the rational allocation of water resources in the Inner Mongolia Autonomous Region was analyzed and calculated to provide scientific suggestions for water resources management and ecological protection in this region. [Methods] Based on the Penman-Monteith formula, this study used measured and multi-source remote sensing data to invert EWR and the ecological water requirement per unit area (ET) for vegetation in four typical regions (western, central, eastern, and northeastern regions) of the Inner Mongolia Autonomous Region from 1990 to 2020. The dominant factors of spatiotemporal variation of ET were determined. [Results] ① EWR showed a trend of decreasing and then increasing over the 30-year study period, with the western region being more stable (maintaining an EWR of around 3.00×1010 m3). The central and eastern regions had EWR of around 6.00×1010 m3, with a large variation and a maximum variation of over 1.00×1010 m3 between years. The northeastern region EWR values were higher and stable at around 1.00×1011 m3. ② EWR was higher in the east and lower in the west, and varied greatly from east to west, with the mean ET value in the northeastern region being nearly 250 mm higher than in the west. [Conclusion] The climatic factors (primarily precipitation and evaporation) and anthropogenic factors (primarily land cover type change) were the key factors for the change of ecological water requirement of vegetation in the Inner Mongolia Autonomous Region, with the latter being more influential than the former.

    • Driving Force Analysis of Spatio-temporal Changes in Vegetation Coverage in Pearl River Delta Based on Geographic Detector Model

      2023, 43(6):336-345. DOI: 10.13961/j.cnki.stbctb.2023.06.039

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      Abstract:[Objective] The driving forces of the spatial distribution and spato-temporal changes in fractional vegetation coverage (FVC) in the Pearl River delta were analyzed in order to provide a scientific reference for the protection of the ecological environment in the region. [Methods] A binary pixel model was used with Landsat 5 TM and Landsat 8 OLI data to invert the vegetation coverage of the Pearl River delta in 2000, 2005, 2010, 2015, and 2020. The spatial pattern and spatio-temporal changes in FVC in the Pearl River delta were analyzed. Annual precipitation, average annual temperature, population density, and land use data during the five study periods were analyzed using correlation coefficients and the geographical detector method. [Results] ① Vegetation coverage in the Pearl River delta was lower in the middle of the region and higher in the marginal regions. Vegetation coverage was lower in Foshan, Zhongshan, Zhuhai, Southwestern Guangzhou, Dongguan City, and Shenzhen City, and higher in Zhaoqing, Jiangmen City, and Huizhou City. Overall, vegetation coverage increased over time, with 64.99% of the total area showing increases in vegetation coverage. There were stage differences in time, and the area with highest vegetation coverage (more than 80%) increased most significantly during 2010-2015. ② There were obvious regional differences in the driving factors of FVC. Annual precipitation and land use had more inhibiting effects than promoting effects, and average annual temperature and population density had more promoting effects than inhibiting effects. ③ The spatial pattern factor detection of FVC showed that the explanatory power of land use degree was the strongest, while the interactive detection showed that the explanatory power of annual average temperature and land use degree interaction was the highest. For the explanatory power of annual precipitation, annual precipitation and annual temperature interaction showed a weakening trend in the time series of 2000, 2005, 2010, 2015, and 2020. The explanatory power of other influencing factors and their interactions showed an increasing trend. The spatial-temporal FVC change factor detection also indicated that the explanatory power of land use degree change was the strongest, while the interactive detection indicated that annual precipitation change and land use degree interaction had the highest explanatory power. [Conclusion] Land use degree was the dominant factor affecting the temporal and spatial changes of vegetation coverage in the Pearl River delta. Human influence continues to increase, and the interaction of the two factors is significantly greater than the effect of a single factor.

    • Spatiotemporal Differentiation and Driving Factors of Green Efficiency of Agricultural Water Use in China

      2023, 43(6):346-357. DOI: 10.13961/j.cnki.stbctb.2023.06.040

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      Abstract:[Objective] The spatiotemporal differentiation and evolution characteristics of the green efficiency of agricultural water use in China and the current status of Chinese agricultural development were analyzed in order to further promote high-quality development of agriculture. [Methods] The super-efficiency evidence-based model (EBM) was used to estimate the green efficiency of agricultural water in 31 provinces and cities during 2001-2020. On this basis, kernel density estimation (KDE) was used to conduct non-parametric tests, and ArcGIS graphics were used to explore the spatiotemporal differentiation and evolution characteristics of the green efficiency of agricultural water use in different regions of China. Finally, the geographical detector method was used to investigate the comprehensive influence of different driving factors on the green efficiency of agricultural water use. [Results] ① From 2001 to 2020, the national green efficiency of agricultural water use (the annual average of each province) initially increased and then decreased. ② The national green efficiency of agricultural water use showed a spatial pattern of "lower in the north and higher in the south", "lower in the west and higher in the east". ③ The regional gap of the green efficiency of water use in China showed a narrowing trend, with dynamic convergence characteristics. The green efficiency of agricultural water use in each province was polarized to varying degrees, among which the nuclear density curve in Northwest China was the most gentle, and the polarization was the most serious. ④ Technical level, resource endowment, and ecological environment had greater influence on the green efficiency of agricultural water use than economic development level. [Conclusion] Each province should combine its own advantages and promote the green efficiency of agricultural water use from the aspects of agricultural technology level and rural social welfare.

    • Spatiotemporal Pattern of Land Cover Types on Loess Plateau

      2023, 43(6):358-368,379. DOI: 10.13961/j.cnki.stbctb.2023.06.041

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      Abstract:[Objective] A long-term and high-precision land cover dataset was constructed for the Loess Plateau. The spatiotemporal pattern of land cover in 2001 and 2020 was analyzed in order to provide a scientific underpinning for initiatives concerning ecological environmental preservation and sustainable development within the region. [Methods] Training samples were constructed using multiple sources of land cover products and ground feature data from various time periods. The Google Earth Engine (GEE) platform and a random forest classification model were used to generate the land cover of Loess Plateau (LCLP) dataset. Spatial analysis and a univariate linear regression model were then used to analyze the spatiotemporal pattern of land cover types on the Loess Plateau. [Results] According to the validation set built using random forest, LCLP exhibited an overall accuracy and kappa coefficient greater than 90%. Moreover, based on the independent verification set, LCLP demonstrated an overall accuracy ranging from 0.58% to 20.23% higher than existing products. Additionally, the accuracy of the classification of various land cover types, including cultivated land, forest land, grassland, impervious surface, and bare land, was increased. [Conclusion] Compared with other datasets, LCLP significantly improved classification accuracy and is suitable for accurately reflecting land cover changes for the Loess Plateau region. During 2001-2020, there has been a decreasing trend in cultivated land and shrubs in the Loess Plateau region, while forest land, water bodies, and impervious surfaces have shown a significant increasing trend. From the perspective of land cover changes, cultivated land and grassland were the primary sources of newly added land cover types.

    • Spatial and Temporal Characteristics of Rural Revitalization Level and Its Influencing Factors—Take Guangdong Province as an Example

      2023, 43(6):369-379. DOI: 10.13961/j.cnki.stbctb.2023.06.042

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      Abstract:[Objective] The levels of rural revitalization and the development levels of its subsystems in various prefecture-level cities in Guangdong Province were evaluated comprehensively, and the spatio-temporal evolution characteristics and influencing mechanisms from 2017 to 2021 were explored, in order to provide scientific references for the continuous advancement of the rural revitalization project. [Methods] A measurement system was constructed based on five subsystems:prosperous industries, affluent livelihoods, civilized rural customs, effective governance, and eco-friendly habitation. The TOPSIS method was employed to assess the level of rural revitalization in Guangdong Province. Hot-spot analysis was used to investigate the spatio-temporal evolution characteristics of rural revitalization levels and the development levels of each subsystem in Guangdong Province. Geographical detectors were applied to clarify the main influencing factors of rural revitalization and the interaction patterns of each factor. [Results] ① During the study period, the level of rural revitalization in Guangdong Province showed a slight increase, and the evolution types of research units were predominantly characterized by grade improvement. The Pearl River Delta region consistently remained a high-value unit aggregation area. Although the development levels of each subsystem changed relatively consistently, there were notable differences in the evolution of research unit types. ② Over the study period, various attributes of research units were generally characterized by hot-spot aggregation, with high-value aggregation areas consistently located in the Pearl River delta. ③ From 2017 to 2021, the main influencing factors of rural revitalization in Guangdong Province were financial support, industrial excellence and economic foundation, and the interaction types of each factor are nonlinear or double-factor enhancement in the two study years. [Conclusion] Over the study period, the rural revitalization level in Guangdong Province displayed modest improvement, with varying evolution trends in the development levels of each subsystem. Notably, spatial heterogeneity was evident, emphasizing the multifaceted nature of factors driving rural revitalization.

    • Spatial and Temporal Changes and Driving Factors of Soil Erosion in North Piedmont of Yinshan Mountain

      2023, 43(6):380-390. DOI: 10.13961/j.cnki.stbctb.2023.06.043

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      Abstract:[Objective] The spatial and temporal changes of soil erosion and its influencing factors in the north piedmont of Yinshan Mountain from 2000 to 2020 were analyzed in order to provide scientific guidance for soil erosion control and land space planning in this area. [Methods] Based on precipitation, land use, soil and remote sensing image data, the research was carried out by using GIS technology and the RUSLE model. [Results] ① From 2000 to 2020, soil erosion intensity in the north piedmont of Yinshan Mountain was mainly micro-grade erosion and moderate-grade erosion. The area of high-grade erosion continued to increase over time. The soil erosion status in the north piedmont of Yinshan Mountain was very severe. ② The areas of severe soil erosion in the north piedmont of Yinshan Mountain were mainly located along the Yinshan Mountain range and most areas of Duolun County, Inner Mongolia Autonomous Region. ③ Land use type was the main influencing factor of soil erosion in the north piedmont of Yinshan Mountain. The explanatory power of each factor followed the order of:land use type > vegetation coverage > rainfall > slope. The area consisting of cultivated land with vegetation coverage less than 0.3, slope of 15°~20°, and rainfall of 365~413 mm was the high risk erosion area. [Conclusion] The degree of soil erosion in the north piedmont of Yinshan Mountain was generally high. Cultivated land and grassland with low vegetation coverage should be the key areas for soil erosion control in the north piedmont of Yinshan Mountain. Soil erosion should be controlled by planting trees and grasses to expand the coverage of forests and grasslands, improve vegetation coverage, reduce surface runoff rate, and improve infiltration capacity.

    • Soil Erosion and Soil and Water Conservation Measures at Xiliugou Watershed in Ten Tributaries Area in Inner Mongolia

      2023, 43(6):391-401. DOI: 10.13961/j.cnki.stbctb.2023.06.044

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      Abstract:[Objective] The Ten Tributaries Area in Inner Mongolia belongs to the sandy and coarse sediment area and the ecologically fragile area in the middle and upper reaches of the Yellow River. A field investigation was conducted on soil erosion at Xiliugou watershed (a typical watershed in the Ten Tributaries area), and the characteristics and causes of soil and water loss in the watershed were analyzed in order to provide a basis for soil erosion control in the Ten Tributaries Area. [Methods] From September 19 to 26, 2022, and from June 21 to 26, 2023, 15 investigation sites and 14 watersheds were respectively set up along the X640 Jiechai (Jiejiaying-Chaijiapu) line and G109 Jingla (Beijing-Lhasa) line to investigate the vegetation, soil, soil erosion characteristics, and water and soil conservation measures of the investigation sites and watersheds. [Results] Grassland erosion in the watershed was observed to be severe, while erosion of cultivated land was not severe. Wind erosion of bare soil was more serious in gullies. In the upstream of loess plateau hilly area, there was severe gully erosion, and the processes of headwind erosion, downcutting erosion, and gully bank expansion had not ceased during the study period. These processes were accompanied by significant gravity erosion. In the midstream sandstorm region, wind-water complex erosion was the main type, which greatly increased the total sediment yield of the watershed. Man-made disturbances such as road construction and slope excavation further increased the risk of erosion. The results of runoff sediment content measurement verified that the main source of sediment in the watershed was from the upstream region. Soil and water conservation measures within the watershed mainly consisted of vegetation and engineering measures. Although these measures have made some contributions to soil and water conservation, they have been relatively limited in their forms, and have not fully achieved the desired effects. [Conclusion] The short duration and high intensity of rainfall that occurs at Xiliugou watershed, combined with soil dominated by arsenic sandstone, have led to soil erosion in the area. Human activities under economic development pressure have exacerbated ecological risks. The local government should continue to increase investment in soil and water conservation, enhance regulatory capabilities, strengthen research on the monitoring and mechanisms of soil erosion, and improve comprehensive soil and water conservation management.

    • Factors Influencing Recessive Transformation of Land Use in Fujian Province During 2000-2020

      2023, 43(6):402-411. DOI: 10.13961/j.cnki.stbctb.2023.06.045

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      Abstract:[Objective] The spatio-temporal characteristics of the dominant driving forces and influencing factors of county land use transition in Fujian Province were analyzed, and a logical analysis framework of influencing factors of land use transition was constructed, in order to provide a reference for the high-quality development of land use in Fujian Province. [Methods] Based on land use data and socio-economic data for Fujian Province in 2000, 2010, and 2020, we constructed a logical analytical framework of the factors influencing land use transformation by using a theoretical analysis method, a land use transfer matrix, a comprehensive index method, and geographically weighted regression. Based on these methods, we conducted a systematic analysis on the dominant driving force of land use transformation, the shift of land classes, the spatial and temporal characteristics of implicit land use patterns, and the influencing factors in Fujian Province. [Results] ① Regions of Fujian Province showed a development trend with economic-ecological security as the main driving force; ② The area of construction land in Fujian Province increased by 2 897.45 km2 during 2000-2020, being mainly converted from arable land, followed by forest land and grassland; ③ Land use recessive morphology in Fujian Province showed a "strip-like" spatial characteristic, forming the Fuzhou-Putian-Xiamen high-level zone and the Fuding-Minhou-Xianyou-Anxi-Zhaoan and Wuyishan-Nanping-Sanming-Longyan intermediate morphology zones; ④ Traffic density and urbanization were the main factors influencing land use transformation in Fujian Province. [Conclusion] Fujian Province should strengthen transportation construction between inland and coastal areas, and between remote and urban areas. Fujian Province should also implement a new urbanization strategy, and at the same time further promote mountain-sea cooperation in the new era, and give full play to the leading role of coastal cities such as Fuzhou City and Xiamen City.

    • Effects of Climate Change and Human Activities on Vegetation Coverage in Arsenic Sandstone Area of Yellow River Basin

      2023, 43(6):412-420. DOI: 10.13961/j.cnki.stbctb.2023.06.046

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      Abstract:[Objective] The arsenic sandstone area is the most serious soil erosion area in the Yellow River basin. Vegetation coverage changes and their driving factors were determined in order to provide a scientific reference for vegetation restoration and ecological reconstruction in this area. [Methods] MOD13Q1 NDVI data from 2000 to 2022 were used with the Sen trend, Mann-Kendall significance test, Hurst index, residual analysis, and other methods to determine the temporal and spatial variation trends of vegetation coverage during the study period in the arsenic sandstone area. The response relationships between vegetation coverage and climatic factors and human activities were also determined. [Results] ① Vegetation coverage in the arsenic sandstone area increased by 4%/yr (p<0.05) from 2000 to 2022. Vegetation coverage in the study area exhibited obvious spatial differences in the three study areas, showing the spatial distribution trends of "higher in the south and lower in the north" and "higher in the east and lower in the west". ② The area with positive correlations between vegetation coverage and precipitation during the study period accounted for 66.30% of the total area, and the area with negative correlations accounted for 33.70% of the total area. The area with positive correlations between vegetative coverage and temperature accounted for 92.19% of the total area, and the negative correlation area accounted for 7.81% of the total area; ③ The residual results showed that human activities in 2000-2011 produced mainly negative effects on vegetative coverage, and human activities in 2012-2022 produced mainly positive effects. [Conclusion] Vegetation coverage in the arsenic sandstone area significantly increased during the study period, and had a higher correlation with annual average temperature than with annual rainfall. A series of ecological protection projects have made significant contributions towards increasing vegetation coverage.

    • Coupling Coordination Relationship Between High-quality Development and Water Resource Protection and Utilization in Urban Agglomerations of Middle Reaches of Yellow River from 2011 to 2021

      2023, 43(6):421-433. DOI: 10.13961/j.cnki.stbctb.2023.06.047

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      Abstract:[Objective] The spatio-temporal coupling coordination relationship between high-quality development and water resource conservation and utilization in the urban agglomerations of the middle reaches of the Yellow River in order to provide decision support and a scientific basis for the sustainable use of water resources and effective protection of water ecology in the region. [Methods] Based on the panel data of high-quality development and water resources protection and utilization in 19 cities in the middle reaches of the Yellow River from 2011 to 2021, the coupling coordination degree of high-quality development and water resources protection and utilization and its spatio-temporal characteristics were analyzed by means of combination weighting, coupling coordination degree model and a geographic detector model. [Results] The level of high-quality development and water resource conservation and utilization in the urban agglomeration of the middle reaches of the Yellow River had improved continuously, and regional disparity has gradually narrowed. The coupling coordination degree of the two systems increased over time, with some areas transitioning from the brink of imbalance to the initial stage of coordination. Furthermore, the coupling coordination degree exhibited positive spatial autocorrelation, radiating outward from the two central cities of Xi'an and Zhengzhou City. The degree of dependence on foreign trade and the proportion of tertiary industry output had significant impacts on the coordination of the two systems, with nonlinear enhancement or mutual strengthening relationships among interactive factors. [Conclusion] To enhance the spatial dependence of high-quality development and water resource conservation and utilization in urban agglomerations of the middle reaches of the Yellow River, it will be necessary to strengthen regional cooperation, optimize water resource utilization structures, improve water resource management capabilities, increase investment in science and technology, enhance regional innovation capacity, and actively promote coordinated regional development.

    • Influencing Factors of Cultivated Land Spatial Protection Pattern and Countermeasures of Regulation Planning—Taking Kongtong District in Pingliang City of Gansu Province as an Example

      2023, 43(6):434-444. DOI: 10.13961/j.cnki.stbctb.2023.06.048

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      Abstract:[Objective] Through analying the causes of the current spatial pattern of cultivated land protection and its spatial correlation, the scientific zoning of cultivated land renovation planning was divided to provide reference for further optimizing the layout of cultivated land, improving the quality of cultivated land, and scientific utilization and protection of cultivated land. [Methods] Taking Kongtong District, Pingliang City, Gansu Province as an example, landscape pattern index method, multi-objective decision-making method, Spreaman rank correlation method and cluster analysis method were used to analyze the synergistic or tradeoff relationship between the current situation of cultivated land landscape pattern and its spatial existence by selecting cultivated land slope, cultivated land protection policy and urbanization impact, and to construct the correlation analysis and evaluation index system of cultivated land protection pattern. [Results] ① As a whole, the cultivated land landscape pattern index of the study area increased by 3.55% from 2010 to 2022, and the degree of cultivated land agglomeration showed a downward trend in most regions, but it fluctuated during the whole process. The regional land use degree showed an upward trend on the whole, and the characteristics of cultivated land layout and land use degree of each township were significantly different. ② The cultivated land protection index in 2022 increased by 315.30% compared with 2010, the cultivated land on 2°-6° slope increased by 120.96%, the cultivated land on 15°-25° slope decreased by 32.64%, and the cultivated land in > 25° decreased by 100%, which was highly coordinated with the cultivated land landscape pattern in space. The urbanization impact index showed an upward trend, which increased by 25.17% from 2010 to 2022. The urbanization impact on cultivated land distribution increased, and there was a significant spatial balance between urbanization and cultivated land landscape pattern. ③ Four units of cultivated land renovation planning were divided as cultivated land quality improvement key area, cultivated land quality improvement general area, cultivated land new development potential area, cultivated land coordination protection area. [Conclusion] The distribution characteristics of cultivated land in Kongtong District of Pingliang City, Gansu Province are different among different towns, and the overall protection effect of cultivated land is obvious. The main factors affecting the spatial pattern of cultivated land in the study area are policy factors, the impact of urban development, farmers' planting willingness and cultivated land protection awareness, etc.