Abstract:[Objective] The sand fixation effects of mechanical sand barrier along typical Yellow River bank in Ulan Buh Desert were studied in order to provide theoretical supports and scientific references for the rational configuration and application of sand barriers in the desert areas along the Yellow River. [Methods] Checkerboard sand barriers comprised of 2 m×2 m gauze, polylactic acid (PLA), and straw were evaluated. Measurements of wind speed at heights of 10, 20, 50, 100, and 200 cm above the three checkerboard sand barrier treatments and the simultaneous collection of aeolian dust from 0 to 50 cm near the surfaces were used to determine the effects of three types of sand barrier on wind prevention and sand fixation after forming a stable barrier surface. [Results] ① The sand barriers of gauze, PLA, and straw all effectively reduced the near-surface wind speed, especially at the height of 10 cm. When the wind speed was 10.32 m/s, the wind protection efficiency of the three sand barriers reached 49.73%, 39.92%, and 38.33%, respectively. ② The wind speed profile of the PLA sand barrier had an S-shaped curve, and the roughness of the three types of sand barriers was greater than observed for the bare dune. ③ Compared with the bare dune, the three types of sand barriers reduced the degree of wind disturbance at the height of 10 cm above the surface. ④ The sediment transport rate of the gauze, PLA, and straw sand barriers showed an exponential relationship with height, and the sand fixation effect was 94.37%, 44.80%, and 53.16%, respectively. Compared with the bare dune, these three types of sand barriers effectively elevated the average saltation height of sand grains, and the gauze sand barrier elevated to 5.35 times that of the control. [Conclusion] According to the aeolian sand activity degree and material acquisition degree along the bank of the Yellow River in the Ulan Buh Desert, the straw sand barrier was useful for sand fixation, the PLA sand barrier was useful for sand fixation and for promoting the growth of vegetation, and the gauze sand barrier was useful for wind protection and sand fixation.

Abstract:[Objective] The differences in protective effects generated by different configurations of farmland shelterbelts were detemined in wind and sand areas, as well as the influencing factors on soil moisture content in fields, in order to provide a theoretical basis for water management and land use in this region. [Methods] Three typical configurations of farmland shelterbelts in the Tenth Regiment of Alar City, Xinjiang Wei Autonomous Region, were studied by measuring soil moisture content, wind speed, light intensity, and air temperature and humidity within different configurations of shelterbelts. [Results] The most significant improvement in field microclimate within the range of 0~1 tree hight was observed with a shelterbelt porosity of 41% in the case of five rows of Populus alba var. pyramidalis. The longest effective protection distance within the shelterbelt with a porosity of 47% was achieved with one row of Populus euphratica and two rows of P. alba var. pyramidalis. Moreover, the soil moisture content in the field was significantly higher for the configuration of one row of P. euphratica and two rows of P. alba var. pyramidalis compared with five rows of P. alba var. pyramidalis and four rows of P. alba var. pyramidalis. The soil moisture content within the shelterbelt of five rows of Xinjiang poplar was primarily influenced by air temperature, humidity, and light intensity. On the other hand, the soil moisture content in the case of four rows of P. alba var. pyramidalis and one row of P. euphratica and two rows of P. alba var. pyramidalis was related to the distance of the shelterbelt and soil depth. Overall, the porosity of the shelterbelt had a direct negative effect on soil moisture content, while soil bulk density indirectly affected the moisture content through soil depth. [Conclusion] By adjusting the configuration and structure of farmland shelterbelts, it is possible to increase the protective efficiency of the shelterbelts and to provide favorable conditions for crop growth in sandy areas. This adjustment can also serve as a theoretical basis for regulating local water resources.

Abstract:[Objective] The influences of soil texture types and parameters of banded sand ditches on soil infiltration processes were studied in order to provide scientific evidence for the design, operation, and management of sand ditch rainwater harvesting projects. [Methods] HYDRUS-2D/3D software was used to establish a mathematical model for soil water movement in a banded sand ditch, and the reliability of simulating the soil infiltration process in a banded sand ditch model was verified using laboratory experiments. The cumulative infiltration and movement of the wetting front under different influencing factors in a banded sand ditch were simulated and analyzed. [Results] The simulated results were consistent with the measured data. The results showed no significant differences, indicating that the established model and its solution method can effectively produce the numerical values of cumulative soil infiltration and wetting front movement at different times in banded sand ditches. There was a significant increase in infiltration in homogeneous soil filled with banded sand ditches. The original soil texture, sand ditch spacing, sand ditch width and sand ditch depth all significantly impacted infiltration rate. Infiltration rate decreased with an increase in the original soil saturated hydraulic conductivity and sand ditch spacing, but increased with an increase in sand ditch width and depth. The soil-wetting front profile formed a U-shaped pattern with a lower front and a higher back. With time, the U-shaped side-wetting front gradually approached the intersection of the sand ditch, and the top plateau gradually disappeared. The original soil texture significantly impacted the migration distance of the wetting front, which increased with an increase in the original soil saturated hydraulic conductivity. Sand ditch depth significantly impacted the shape and distribution of the wetting front. With an increase in sand ditch depth, the U-shaped pattern stretched vertically, and the wetting depth on the left side increases significantly. The change in wetting depth on the right side was minimal. Sand soil texture, sand ditch spacing, and sand ditch width had relatively minor impacts on the migration distance of the wetting front. [Conclusion] Banded sand ditch structures can significantly improve soil infiltration capacity. Soil texture types and sand ditch structure parameters have different effects on soil cumulative infiltration and wetting front migration distance.

Abstract:[Objective] The effects of cellulose-based soil amendments prepared from corn cobs and humic acid on erosion resistance of sandy soil were assessed in order to provide a scientific reference for the management of regional soil erosion problems. [Methods] One or two mixtures of laccase and lignin peroxidase, three enzyme activities, two corn cob biomass addition levels, and a fixed amount of humic acid were used to synthesize cellulose-based soil amendments through aqueous solution polymerization. Infrared spectroscopy was used to characterize enzymatic hydrolysis products and functional groups of amendments. The water retention capacity and network characteristics of the amendments were analyzed based on their swelling characteristics. In addition, the effect of amendments on erosion resistance of sandy soil was also evaluated based on the parameters related to mechanical and water-stable aggregates. [Results] ① The water absorbency of the cellulose-based soil amendments was about 0.61—4.84 times that of pure humic acid-based amendments for which the soil amendment prepared by adding 4 g of enzymatic hydrolysis products of laccase (20 U) and lignin peroxidase (20 U) hydrolysate had the highest water absorbency value (66.7 g/g). The swelling process of the soil amendment corresponded to Schott’s second-order kinetic model. ② Compared with the control group, the addition of 1% amendments (Lac_3-4, Lip_3-4, and LLP_3-4) synthesized by the three different enzymatic hydrolysis schemes increased the soil saturated water content by 20%—60%. LLP_3-4 increased the content of mechanical macroaggregates and water-stable macroaggregates (＞0.25 mm) by 6 and 14 times, respectively, and increased the average weight diameter and geometric average diameter of soil by 70.59% and 46.67%, respectively. The fractal dimension was decreased by 21.36%. [Conclusion] Cellulose-based soil amendments prepared by a dual-enzyme pretreatment scheme can significantly increase the water retention capacity and erosion resistance of sandy soil.

Abstract:[Objective] The disturbance effects of accessory facilities of high-grade highways were revealed at different heights in windy and sandy areas on the passing sand flow, the degree of sand deposition on the road surface was explored under the influence of different heights and highway facilities, in order to provide theoretical basis for the design of highway engineering and the formulation of protective measures for sand crossing highways. [Methods] The computational fluid dynamics (CDF) numerical simulation method was used for the analysis, and an ordinary highway was used as a control. The findings regarding the impact of highway structures and different roadbed heights on roadbed transit airflow and the resulting formation of deceleration zones on the highway were validated against field-measured data. [Results] The varying heights of roadbeds resulted in different changes in horizontal airflow velocity. When the height of the roadbed ranged from 1 m to 2 m, the airflow disturbance was relatively weak, thereby facilitating the transport of sand across the highway. In contrast, when the height of the roadbed reached 3 m, the airflow disturbance became stronger, and hindered the transport of sand across the highway. When the airflow traversed the guardrail and the central barrier, it flowed beneath the guardrail, resulting in an increase in wind speed. The distance at which the maximum wind speed occurred on the leeward side of the guardrail initially increased and then decreased with increasing elevation of the roadbed. Specifically, at roadbed heights of 0 m, 1 m, 2 m, and 3 m, the distances at which the maximum wind speed occurred were measured to be 10 cm, 20 cm, 25 cm, and 20 cm, respectively. Subsequently, the airflow combined with the upper layer on the leeward side of the guardrail, resulting in continuous diffusion of the tail flow. This led to the formation of a deceleration zone where the transit airflow weakened. As a result, sand particles began to be deposited, resulting in a maximum height of sand accumulation of 11.5 cm. The width of sand accumulation ranged between 4.0 m and 4.5 m. [Conclusion] The height of the roadbed and the presence of road structures were identified as the primary factors contributing to sand damage along highways. Roadbed height had a significant impact on the wind speed above it. The installation of guardrails and anti-glare nets can create a low wind zone on the leeward side of the structures, resulting in sand accumulation on the highway that can pose potential hazards.

Abstract:[Objective] The reasonable configuration pattern of multi-row Z-shaped sand barriers was studied in order to provide a reference for wind and sand protection in the gobi saline-alkaline area along the Hetian-Ruoqiang Railway (HRR). [Methods] Experiments were carried out in a wind tunnel to simulate the local blown-sand environment and to test the sand-control effect of multiple rows of Z-shaped upright sand barriers with a porosity of 40%. [Results] Sand accumulation behind the folded corner of the sand barrier was separated when the angle between the face of sand barrier and the wind direction was an obtuse angle. Sand accumulation behind the folded corner of the sand barrier was aggregated when the angle between the face of the sand barrier and the wind direction was an acute angle. The sand prevention efficiency of two and three high vertical sand barriers decreased with increasing wind speed. When the wind speed was 12 m/s (level 7 wind), the sand prevention efficiency of two and three high vertical sand barriers were 74.0% and 100% respectively. When the wind speed increased to 15 m/s (level 9 wind), the respective sand prevention values were 72.7% and 88.9%. [Conclusion] It is recommended that three sand barriers should be used, with the windward side of the barriers positioned at an obtuse angle to the wind direction as far as possible.

Abstract:[Objective] The spatial distribution characteristics and influencing factors of surface soil water-holding capacity were explored in a karst forest in order to provide scientific references for improving the water conservation capacity of forest soil in the region. [Methods] The surface soil (0—10 cm) of a primary Maolan karst forest in Guizhou Province was taken as the research object, and the physical structure and water-holding characteristics of soil were measured by the ring knife method and the indoor soaking method. The spatial distribution differences and influencing factors of soil water-holding capacity in different terrain locations were investigated by using variance analysis and RDA analysis. [Results] ① Soil physical characteristics showed high heterogeneity, and soil bulk density, soil water content, porosity, and mechanical composition had significant differences in different slope directions, slope positions and altitudes. ② Soil water retention had the most significant difference in different slope direction, and soil water retention had the most significant difference in different rock exposed grades. The maximum soil water-holding capacity, capillary water-holding capacity, saturated water-holding capacity, and capillary water-holding capacity increased with increasing slope position and elevation, and with decreasing rock exposure grade. The comprehensive water-holding capacity of soil was greater in the area of low exposure and low elevation. ③ Correlation analysis showed that topographic characteristics and soil physical characteristics were more strongly correlated with soil water-holding capacity; stand characteristics were more strongly correlated with water-holding capacity; stand density was significantly negatively correlated with water-holding capacity; and average DBH (diameter at breast height) and average tree height were significantly positively correlated with water-holding capacity. ④ The results of PCA analysis showed that soil water retention was the first main factor to represent the surface soil water retention performance of the Maolan karst forest, and soil water retention rate was the second main factor. The cumulative contribution rate of principal components Ⅰ and Ⅱ was 77.5%. RDA analysis results showed that soil porosity and rock exposure grade were the main factors affecting the water-holding capacity of surface soil in the Maolan karst forest. [Conclusion] The soil water-holding capacity of the Maolan karst forest exhibited high heterogeneity and significant differences among different terrain locations, and non-capillary porosity (P_nc) was the main factor affecting soil water-holding capacity.

Abstract:[Objective] The freeze-thaw adaptability of frost-resistant artificial soil and its application effects in slope vegetation restoration were studied by use of indoor and outdoor tests of various soil physical and chemical indexes in order to provide scientific support and a basis for the application of slope vegetation restoration in an alpine region. [Methods] The physical and chemical properties of soil after 60 freeze-thaw cycles were measured by indoor tests, and representative indexes were selected by principal component analysis for outdoor tests. The practical application effect of artificial soil in Xizang alpine region for four yesrs was monitored by outdoor sampling. Natural soil was used as a control sample during both indoor and outdoor tests. [Results] Compared with natural soil, the freeze-resistant artificial soil had significantly improved its freeze-resistant stability and fertility (p<0.05), which was reflected in that the relative dynamic elastic modulus, ＞0.25 mm water stable large aggregate content, average weight diameter, aggregation degree, organic matter, ammonium nitrogen, nitrate nitrogen, available phosphorus, and available potassium content in frost-resistant artificial soil were significantly greater than that in the natural soil before and after freeze-thaw (p＜0.05). While the mass loss rate and structural failure rate in frost-resistant artificial soil were significantly decreased. Principal component analysis showed that the relative dynamic elastic modulus, structural failure rate, pH value, and organic matter content in indoor tests were highly correlated with principal component factors. Therefore, these four indicators were selected for outdoor sampling and monitoring of vegetation restoration in the field. The monitoring results showed that the structure failure rate was lower, and the relative dynamic elastic modulus, and organic matter content of frost-resistant artificial soil were greater than for the natural soil at different time periods in four yesrs. In terms of vegetation restoration effect, the vegetation coverage, species diversity, aboveground biomass, and underground biomass for frost-resistant artificial soil were greater than for natural soil. [Conclusion] Frost-resistant artificial soil has better vegetation restoration effect when applied in alpine region, especially its freeze-resistant durability, aggregate stability and fertility are outstanding, which are better than natural soil, so it is more suitable for slope vegetation restoration application.

Abstract:[Objective] The dynamic process of erosion evolution of granite weathered soil under the action of changing hydrodynamic head was determined to study the influence of dynamic hydraulic conditions on the development of internal erosion of soil, and to define the particle migration law and internal erosion mechanism, in order to provide a theoretical basis for the in-depth study of the destruction mode and slip-promoting mechanism of granite slopes. [Methods] A vertical soil column seepage device was designed to carry out seepage tests on granite-weathered soil columns under rising hydrodynamic head and sinusoidal head conditions. Based on the test observations at the top and sides of the seepage soil columns, the developmental characteristics of the internal erosion of granite weathered soils under the action of changing hydrodynamic head were analyzed in terms of the changes in seepage velocity, the amount of soil particles lost, particle gradation, and quality of the particles before and after seepage. [Results] ① Granite-weathered soil had large differences in particle size, and there were small pores in the soil matrix. Seepage and scouring effects transported soil particles through the pores in the soil matrix. The amount of fine particles lost through internal erosion was relatively large, and the amount of coarse particles lost was small. ② Internal erosion was a gradual development process, and the soil structure in the weak areas of the soil was the first to exhibit deformation and damage. In the test, the seepage springs progressed from the boundary of the soil column to the middle area of the soil column, and the seepage channels developed from bottom to top along the seepage direction. Significant changes in the hydraulic conditions within a short period of time resulted in rapid penetration of the seepage channels. ③ Internal soil erosion will stabilize with seepage time, but a sinusoidal hydrodynamic head will activate the movement of soil particles and intensify internal soil erosion. Increasing the magnitude or decreasing the period of the head change can increase the internal erosion of soil, resulting in faster water transport and increased loss of particles through migration. [Conclusion] Changes in hydraulic conditions had a significant effect on erosion within the soil, with sinusoidal heads exacerbating particle migration and loss.

Abstract:[Objective] The impact of different gravel contents on soil erosion of engineered deposit slopes were explored in the sandy soil region of Northern Shaanxi Province under continuous rainfall conditions in order to provide data support and theoretical references for soil erosion control in production and construction projects. [Methods] Indoor rainfall experiments were conducted to study the hydrodynamic, runoff, and sediment characteristics of engineered deposit slopes with varying gravel contents (0%, 10%, 20%, 30%, 40%). [Results] ① Under the same rainfall intensity, the initial runoff time on the engineered deposit slopes showed a decreasing trend with the increase of gravel content, with ranges of 27.22%—64.62%, 35.09%—71.70%, 47.37%—78.77%, and 51.75%—82.31%, respectively. The runoff coefficient during subsequent rainfall events exhibited a “rapid increase-stable fluctuation” trend, and the average runoff coefficient increased significantly with increasing gravel content and rainfall duration. However, the peak value of runoff decreased with increasing gravel content, and the occurrence time of the runoff peak was gradually advanced. ② The Reynolds index for all experiments ranged from 74.13 to 165.05, all of which were below 500, indicating that the flow type was laminar flow, while the Froude number ranged from 2.14 to 3.7l indicating rapid flow. The shear force, flow power, and unit flow power increased with increasing rainfall time. ③ The ranges of erosion modulus on the engineered deposit slopes were 0.45—6.73, 0.13—4.09, 0.25—1.26, 0.14—0.96, and 0.13—0.88 g/(m²·min), respectively. The sediment reductions for each gravel content were 36.06%, 49.05%, 55.23%, and 56.62%, respectively. The highest gravel coverage (40%) resulted in the lowest soil erosion intensity of the engineered deposit slopes in the sandy soil region. [Conclusion] Gravel coverage on engineered deposit slopes of sandy loam soil significantly reduces soil erosion rate, thereby achieving soil retention and maintaining high sediment reduction benefits.

Abstract:[Objective] A design scheme was proposed involving the addition of hydrophilic polyurethane (W-OH, a highly water-resistant material) under disturbed soil conditions to reconstruct a bottom water-resistant layer (approximately seamless impervious layer) in order to alleviate the adverse effects of water factors on the failure of disturbed soil to form frozen soil in a high cold mining area. Changes in slope infiltration, flow production, and sediment production of weathered coal gangue after the reconstruction of a water-blocking layer in an alpine mining area were studied to provide theoretical support for the recurrence of frozen soil on a disturbed slope and the prevention and control of soil erosion on a slope after the reconstruction of a water-blocking layer. [Methods] Simulated artificial rainfall was applied at rates of 60 mm/h and 90 mm/h to reconstructed water-blocking layers having W-OH concentrations of 0%, 1.5%, 2.5%, 3.5%, and 4.5%. Infiltration characteristics and soil and water loss changes of the weathered coal gangue slope under three different slope conditions (5°, 15°, 25°) were obtained. [Results] ① The stable infiltration rate of the coal gangue slope after application of a reconstructed water-blocking layer was significantly lower than that of natural slope, and was negatively correlated with W-OH concentration. ② The flow yield of the coal gangue slope showed a trend of rapid increase at first and then gradually becoming stable over time, and the average flow yield showed a positive correlation with the W-OH addition concentration. The average runoff yield of coal gangue slopes with 1.5%, 2.5%, 3.5%, and 4.5% W-OH increased by 26.75%, 38.02%, 46.90%, and 63.23%, respectively, compared with the natural state. ③ The average slope velocity was positively correlated with rainfall intensity, W-OH addition concentration, and slope, and the influence degree followed the order of rainfall intensity＞slope addition concentration＞W-OH addition concentration. ④ The variation curve of slope sediment yield over time was mostly a “unimodal” curve, which showed a rapid rise at first, then a slow decline and finally tends to be stable. The average sediment yield of coal gangue slopes with 1.5%, 2.5%, 3.5%, and 4.5% W-OH increased by 26.98%, 49.48%, 71.64%, and 94.01% compared with the natural state. [Conclusion] The reconstructed water-blocking layer significantly reduced the permeability of weathered coal gangue on the slope, thereby effectively helping the recovery and formation of frozen soil on disturbed slopes in high, cold, mining areas. However, the decrease in infiltration rate could make the slope more prone to runoff and increases sediment production on the surface, and therefore, certain soil and water conservation measures should be applied.

Abstract:[Objective] The characteristics and influencing factors of soil runoff on fish-scale pit slopes in the southern slope of the Taihang Mountains were studied in order to provide scientific basis for soil erosion control and ecological environment protection in the area. [Methods] The study focused on the fish scale pits and natural barren slopes of the southern foothills of the Taihang Mountains. The runoff characteristics on slopes having different vegetation types including herbs, shrubs, and trees were measured, and the influencing factors were determined. The geographic detector statistical method was used to quantify the individual and interactive effects of various factors on slope runoff. [Results] ① There was no significant difference in the average runoff depth between herb, shrub, and tree communities on the fish scale pits. However, the average runoff depths of the shrub and herb communities on the natural barren slopes were significantly greater than that of the tree community. Compared to the natural barren slopes, the average runoff depth decreased by 56.61%, 72.80%, and 39.58% in the herb, shrub, and tree communities on the fish scale pits, respectively. The average runoff depth showed a decreasing trend with increasing gravel content. The control effect of gravel coverage on slope runoff had a threshold, and the minimum slope runoff depth was observed when the gravel coverage ranged from 6% to 9%. ② The single-factor influence of gravel coverage (0.31) was the highest on runoff of fish-scale pit slopes in the southern foothills of the Taihang Mountains, followed by vegetation coverage (0.29). ③ The interaction of slope runoff influencing factors mostly exhibited nonlinear enhancement and dual-factor enhancement effects. The interaction between rainfall and non-rainfall factors showed nonlinear enhancement effects. [Conclusion] The presence of a large amount of gravel contributed to the complexity of runoff processes on fish-scale pit slopes in the southern foothills of the Taihang Mountains. Increasing vegetation coverage is an important measure to reduce slope runoff in this region.

Abstract:[Objective]The influences of slope inclination aspect on hydrological characteristics in the soil surface layer and on the greening steep slopes were studied in order to provide a basis for the effective use of water resources in the process of vegetation restoration on steep loess slopes. [Methods] We conducted a comprehensive study on two steep slopes with inclinations of 46°~55° and 56°~65° located in arid and semi-arid regions. These slopes were categorized into four slope orientations: shady slopes, semi-shady slopes, sunny slopes, and semi-sunny slopes. Arboriculture and shrubbery greening initiatives were implemented on these steep slopes over an 8-year period. We conducted extensive analyses on basic soil properties, water-holding capacity, and infiltration of the 0—40 cm soil layer. Furthermore, we explored the intricate relationship between various soil factors and terrain factors. [Results] ① The interaction between slope classes and slope orientations stand factors had a significant effect (p<0.05) on soil bulk weight, mass water content, total porosity, and maximum water holding capacity in the 0—40 cm soil layer, and a significant effect (p<0.05) on soil gross tubular porosity and gross tubular water holding capacity in the 0—20 cm soil layer, However, these differences were not statistically significant (p>0.05) under alternative conditions. ② Maximum water-holding capacity was found to be higher for the 46°~55° steep slopes than for the 56°~65° steep slopes. Conversely, the average infiltration rate was higher for the 56°~65° steep slopes than for the 46°~55° steep slopes. Sunny slopes had the highest maximum water-holding capacity (522.42 t/hm²), followed by semi-sunny slopes (505.03 t/hm²), shady slopes (502.27 t/hm²), and semi-shady slopes (496.15 t/hm²). Similarly, the average soil infiltration rate was highest for sunny slopes (0.79 mm/min), followed by semi-sunny slopes (0.59 mm/min), shady slopes (0.42 mm/min), and semi-shady slopes (0.30 mm/min). ③ A two-factor analysis of variance revealed that the interaction between slope class and slope aspect had the most significant impact on the hydrological characteristics of steep slopes. [Conclusion] Basic soil properties were better for 46°~55° steep slopes than for 56°~65° steep slopes. Moreover, sunny and semi-sunny slope orientations exhibited greater water-holding capacities than shady and semi-shady slope orientations.

Abstract:[Objective] A cross-regional index system was established based on quantitative values to evaluate the runoff retention capacity for slopes of different soil types managed under different practices in order to provide scientific guidance for the prevention and control of soil erosion. [Methods] Runoff plots with four kinds of management measures were set up on a gray calcium soil slope and a brown red soil slope of the northern slope of Yining City, Xinjiang Wei Autonomous Region, and on a purple soil slope of Dashi River basin, Chishui City, Guizhou Province. Based on observed natural rainfall and runoff data from April to September in 2019 to 2021, runoff coefficient, runoff curve number (CN value), and rainfall-runoff production threshold data were used to quantitatively compare the runoff reduction capacity of 12 runoff plots. [Results] The runoff retention capacity of different soils followed the order of gray calcium soil < brown red soil < purple soil, and the CN values were 90.05, 89.53 and 77.36, respectively. The rainfall-runoff production thresholds were 3.44, 3.50, and 14.96 mm, respectively. The results of different evaluation indexes showed that runoff retention capacity of gray calcium soil and brown red soil management measures followed the order of dry grass cover > horizontal ditch > seepage hole > control. Slope flow reduction ability of the purple soil management measures followed the order of garden land > grassland > cultivated land > control. When the runoff coefficient for the control plot increased by 1%, the runoff depth of gray calcium soil, brown-red soil, and purple soil increased by 1.73, 2.61, and 6.79 mm, respectively. When the CN value was increased by 1, the runoff depth of the three soil slopes decreased by 1.00, 1.00, and 0.71 mm, respectively. [Conclusion] When evaluating runoff reduction capacity of slopes of different soil types across regions, it is recommended to use CN value and rainfall-runoff production threshold, but not runoff coefficient.

Abstract:[Objective] The sand-blocking ability of Tetraena mongolica and Reaumuria soongorica shrubs were comparative studied in the West Ordos area in order to provide a theoretical basis and data support for the protection of plant diversity and conservation of rare and endangered species in the transition zone between native grassland and desert. [Methods] Nebkhas of Tetraena mongolica and Reaumuria soongorica were studied in the West Ordos National Nature Reserve. The morphology and growth of Tetraena mongolica and Reaumuria soongorica were systematically determined by typical sampling methods to determine the relationship between the morphology and development of nebkhas, and to determine the sand-blocking ability resulting from the specific morphology of Tetraena mongolica and Reaumuria soongorica. [Results] ① Both Tetraena mongolica and Reaumuria soongorica nebkhas showed a semi-ellipsoidal development strategy, and the morphological parameters of Tetraena mongolica nebkhas were significantly larger than those of Reaumuria soongorica nebkhas (p<0.05). ② There was a significant correlation (p<0.01) between both Tetraena mongolica and Reaumuria soongorica shrubs and the morphological parameters of sand piles (except shrub height). There were quadratic relationships between the long axis and height, the short axis and height, and the radius and height of sand piles for Tetraena mongolica, indicating that Tetraena mongolica may enter the declining stage. There were linear relationships between the long axis and height, the short axis and height, and the radius and height of sand piles for Reaumuria soongorica, indicating that Reaumuria soongorica nebkhas were still developing. ③ When the crown area (S_p) was less than 1.44 m², the volume of a Reaumuria soongorica shrub was larger than that of a Tetraena mongolica shrub. When S_p＞1.44 m², the volume of a Tetraena mongolica shrub was always larger than that of a Reaumuria soongorica shrub. The sand volumes intercepted by a unit crown area of Tetraena mongolica and Reaumuria soongorica shrubs were 0.13 m³ and 0.06 m³, respectively. [Conclusion] It can be preliminarily surmised that the sand-blocking ability of Tetraena mongolica is greater than that of Reaumuria soongorica. Overall, the adaptability of Tetraena mongolica to a windy-sandy environment is greater than that of Reaumuria soongorica, and the ability of Tetraena mongolica to intercept sand material increases as crown area increases.

Abstract:[Objective] Soil strengthening and slope protection effects of two kinds of herbaceous plants were explored on red clay slope in order to provide scientific references for the ecological management of this type of slope, river channel, and dam. [Methods] With red clay slope as the research object, Cynodon dactylon and vetiver grass were selected as slope protection plants. The slope protection effect of the two herbaceous plants was determined through planting tests, root tensile tests, direct shear tests, and indoor simulated scouring tests. [Results] ① Within 150 days of planting, both herbaceous plants grew steadily and the tensile strength of the root system continued to increase. From 30 to 150 days of growth, the maximum tensile strength of Cynodon dactylon roots increased from 0.84 N to 8.59 N, and that of vetiver grass increased from 4.78 N to 89.89 N. ② At 120 days of growth, the cohesion of the Cynodon dactylon root-soil complex was 91.1% greater than the cohesion of rootless soil, and the angle of internal friction increased by 12.45%. The cohesion of the vetiver grass root-soil complex was 107.47% greater than that of rootless soil, and the angle of internal friction increased by 12.74%. ③ The runoff rate of the Cynodon dactylon slope at 150 days of growth was 45.02% to 54.15% less than observed on a bare slope, while the sediment yield rate was 58.3% to 93.85% less, and the 60 min cumulative sediment yield was 81.02% less. Similarly, the runoff rate of the vetiver grass slope was 35.46% to 46.48% less than observed on a bare slope, while the sediment yield was 46.8% to 89.44% less, and the 60 min have sediment yield was 74.61% less. [Conclusion] Both herbaceous plants had excellent soil consolidation and slope protection effects on red clay slopes, with vetiver grass having a more pronounced effect on the increase in soil shear strength, and Cynodon dactylon having a more significant effect on soil and water conservation.

Abstract:[Objective] Investigations on rainstorm and flood processes and soil and water conservation in Beijing-Tianjin-Hebei region from July 29 to August 1, 2023 (referried as “7·23”) were carried out， and the rainstorm and flood processes in small basins and soil erosion caused by rainstorm were analyzed, in order to provide scientific support for soil and water conservation decision-making. [Methods] Field survey methods were used, in which flood marks were measured and investigated at Huangmi xigou and the Liangjiazhuang donggou of Lincheng County, Xingtai City, Hebei Province. The flood peak discharge modulus was calculated to analyze the erosion damage caused by rainstorm floods to small watersheds. [Results] ① The rainfall lasted for a long time and was strong. The cumulative rainfall in the Liangjiazhuang donggou valley and the Huangmi xigou valley reached 1 008.5 mm and 613.6 mm, respectively. ② According to the flood mark survey, the peak discharge modulus of the Huangmi xigou and the Liangjiazhuang donggou watersheds were 10.80 m³/(s·km²) and 36.07 m³/(s·km²), respectively. Slope and soil and water conservation measures were the main factors affecting flood peak discharge. Larger slopes will increase flood peak discharge, and soil and water conservation measures could play an effective role in peak reduction. ③ The investigated small watersheds were located in the upper reaches of the river basin, which is the main runoff producing area of the rainstorm center and flood. The peak flood discharge modulus of the small watersheds was larger than that of the downstream hydrology station. ④ The erosion situation of the Liangjiazhuang donggou was more serious than that of the Huangmi xigou, mainly due to the following reasons: the area proportion of orchards, terraces, and check dams in the Huangmi xigou was larger than that of the Huangmi west ditch; the average slope of the Huangmi xigou was smaller than that of the Liangjiazhuang donggou; and the peak duration of rainfall at the Liangjiazhuang rain-measuring station was longer. [Conclusion] Optimized soil and water conservation measures can effectively reduce the occurrence of flood peak discharge and erosion phenomenon. The implementation of soil and water conservation measures is necessary and effective. The construction of terraces and terrace valleys must be further improved.

Abstract:[Objective] Risk monitoring and early warning were studied based on the geological disaster chain of landslides and debris flows in Yuanyang terraced fields in order to improve the accuracy of warnings related to rainfall-induced landslides and debris flow disaster chains and to provide a scientific basis for improving the pertinence of work related to reducing and preventing such disasters. [Methods] This investigation delved into the failure process of disaster chains related to landslides and debris flows in the Yuanyang terraced area through rainfall model simulation experiments. Real-time monitoring of rainfall, volumetric moisture content, and slope deformation coupled with an analysis of the early-warning thresholds for disaster chain risks under various rainfall conditions formed a crucial part of the study. Four specific rainfall conditions 〔i.e., long-term moderate rain (50 mm/h), long-term heavy rain (120 mm/h), cyclic intermittent heavy rain, and drought-sudden heavy rain〕 were established. [Results] The continuous impact of rainfall revealed the development stages of the disaster chain, progressing through surface scouring, creeping, rapid sliding, and debris flow migration until the culmination of the movement process. Slope damage initiated from the foot of the left slope, subsequently affecting the foot of the right slope. Various forms of slope damage manifested themselves under distinct rainfall conditions: transverse cracks appeared in the middle of the slope during heavy rain, resulting in the formation of two landslides (one above and one below); multiple landslides occurred consecutively under moderate rain conditions; and mudslides formed rapidly under drought-sudden heavy rain, covering the longest distances and accumulating over a broader area than observed for other rainfall scenarios. [Conclusion] The main monitoring indicators for disaster chain early warning of landslide and debris flow include cumulative rainfall, duration of rainfall, changes in moisture content, and on-site monitoring of slope deformation development. These monitoring parameters are influenced by various factors such as rainfall conditions, soil properties, slope angle, and external dynamic conditions. Therefore, in practical applications, it is necessary to comprehensively consider these factors.

Abstract:[Objective] The health status and ecological functions of forest ecosystems were studied in karst areas through remote sensing monitoring of forest volume in order to provide theoretical basis for carbon sink monitoring and assessment, as well as forest management and decision-making in the region. [Methods] Sentinel-2A images and sample plot survey data were acquired for typical karst mountainous areas. Three machine learning models, including random forest (RF), K-nearest neighbor (KNN), and back propagation (BP) neural network, were combined to conduct a study on forest volume inversion under mountain slope conditions. [Results] ① The performance of single-band reflectance, vegetation index, and texture features varied under different topographic constraints, and the optimal subsets of models established were different. There were differences in the establishment of forest volume estimation models under different site conditions. ② For forest volume estimation in the karst mountainous area, RF had the strongest robustness and adaptability compared with KNN and BP. For gentle slope, inclined slope, and steep slope conditions, the accuracy of RF reached 80.1%, 79.0% and 80.5%, respectively. [Conclusion] Karst mountainous areas have strong spatial heterogeneity, and the modeling independent variables involved in the remote sensing estimation of storage volume are not the same under different slope site conditions. Categorizing slope conditions can refine the remote sensing estimation model of complex scenes and improve the accuracy of remote sensing estimation of forest volume.

Abstract:[Objective] The interaction between environmental variables and economy was determined. The relationship between green GDP (GGDP) and GDP and future trend were studied, and the feasibility of replacing GDP with GGDP as a policy indicator was analyzed in order to promote the implementation of sustainable development. [Methods] Based on system of integrated environmental and economic accounting (SEEA), the correlations between environmental factors and GDP were determined for six representative countries differing in economic structure, development level, and policy system. A univariate linear regression equation was used to fit and analyze the GDP and GGDP of each country. The ARIMA, Holt-Winters, and grayscale GM (1,1) models were used to predict and analyze the GGDP and GDP data, and the optimal prediction results were analyzed by comparing the model errors. [Results] In the early stage of economic development, GDP showed a negative correlation with GGDP and environment. With the improvement of sustainable economic structure, the negative correlation gradually eased, and finally achieved recovery, showing a U-shaped trend. The results of the predictive analysis showed that the ARIMA model was best for predicting GDP, and the Holt-Winters model was best for predicting GGDP. Both GDP and GGDP showed a growth trend, but the growth rate of GGDP was not as fast as GDP. [Conclusion] It is suggested that, combined with China’s actual situation, China’s economic accounting indicator should shift from GDP to GGDP, and should increase environmental and economic investment, thereby achieving sustainable economic, social, and environmental development, and building a resource-saving and environment-friendly sustainable development society.

Abstract:[Objective] The optimal model for predicting total phosphorus concentration in water bodies was studied in order to provide support for accurate, real-time, and efficient monitoring of water resources. [Methods] Water quality samples were collected in 2021 from the Wuhan-Anhui region in the middle and lower reaches of the Yangtze River. Firstly, the collected spectral data of the Yangtze River was preprocessed by both maximum-minimum normalization and mean centering to unify the range and mean point of the data. Kernel principal component analysis (KPCA) was then used to perform dimensionality reduction on the preprocessed spectral data. Six feature vectors were selected based on a variance explanation rate of 99.6% for training the subsequent prediction model. Next, an improved particle swarm optimization (IPSO) algorithm was proposed by introducing an adaptive inertia weight updating formula and a genetic-simulated annealing mutation concept to enhance the optimization ability of the algorithm. The improved particle swarm optimization algorithm was used to optimize the hyperparameter combinations in the support vector regression (SVR) model. The support vector regression model was trained using the output results to predict the total phosphorus concentration. Finally, the test set data were used to predict total phosphorus concentration. [Results] A prediction model for total phosphorus content in water using an improved particle swarm optimization (IPSO) combined with support vector regression (SVR) and spectral dimensionality reduction was proposed. The experimental model achieved an R² of 0.973920, a root mean square error of 0.003012, and a mean absolute error of 0.002105 when predicting total phosphorus concentrations in the Yangtze River water. [Conclusion] The proposed method of using spectral data combined with dimensionality reduction techniques, particle swarm optimization algorithms, and machine learning models was determined to be feasible and effective in total phosphorus concentration measurement. The accuracy and fitting effects of the model were better than the accuracy obtained with several well-performing machine learning models.

Abstract:[Objective] The long-term target value and stage target values of soil and water conservation rate were discussed and defined in Shaanxi Province in order to provide scientific support for accurately evaluating the effect of soil and water conservation work and to scientifically promote the comprehensive prevention and control of soil and water loss. [Methods] The social and economic conditions and the natural conditions of Shaanxi Province were comprehensively considered to analyze the change of soil and water loss area and the change of soil and water conservation rate using the assessment results from annual water conservancy yearbooks and national soil and water conservation planning. Spatial data for soil erosion classification, land use, elevation, topography and vegetation cover data were obtained. The situation of soil and water loss control in Shaanxi Province was studied. The long-term target value of soil and water conservation rate in 2050, and the stage target values in 2025, 2030 and 2035 were determined. These results were combined with a target responsibility system assessment, and a process to achieve the target rate of soil and water conservation was proposed. [Results] ① Since 2011, the area of soil and water loss for the entire province has decreased from 72 686 km² to 62 637 km² in 2022. ② By 2050, after implementation of soil and water loss control measures, the area of soil and water loss is expected to be reduced by 21 607 km² and the long-term target value of soil and water conservation rate will be 79.02%. ③ The stage target values for 2025, 2030, and 2035 will be 71.42%, 73.97%, and 75.62%, respectively. [Conclusion] Scientific and reasonable determination of the target value of soil and water conservation rate in Shaanxi Province can meet the needs of carrying out the assessment of the ecological civilization construction target and the assessment of soil and water conservation target in Shaanxi Province.

Abstract:[Objective] The relationship between rainfall intensity of different durations and regional landslide disasters was studied, and the meteorological warning threshold of landslide disasters was determined in order to provide a scientific basis of geological disaster warnings for local administrative departments. [Methods] Hourly rainfall data from 348 rainfall stations in the study area during 2013—2021 were collected, as well as the time and location of 231 disaster and dangerous landslide events that have occurred in the past 10 years. Based on the average rainfall intensity (I)—rainfall duration (D) model, the dataset was divided into geomorphic units. Critical rainfall warning thresholds were proposed, and graded warning thresholds for different rainfall durations were determined. [Results] Red warning thresholds for the average rainfall intensity at 1, 3, 6, 12, 24, and 48 hours under different early rainfall conditions in the hilly terrain area of the study area were 29.774, 18.579, 14.416, 11.186, 8.679 and 6.734 mm, respectively. The red warning thresholds for the average rainfall intensity at 1, 3, 6, 12, 24 and 48 hours under different early rainfall conditions in low mountain terrain areas were 28.849, 15.542, 10.520, 7.121, 4.820 and 3.263 mm, respectively. [Conclusion] Under the condition of rainfall in the early 24 hours period, the sensitivity of low mountainous areas to rainfall was significantly higher than the sensitivity of hilly areas. The critical warning thresholds at 1, 3, 6, 12 and 24 hours in low mountainous areas were significantly lower than those in hilly areas. However, with the further extension of rainfall duration, the critical warning thresholds at low mountainous areas and hilly areas tended to be similar.

Abstract:[Objective] The influence of rainfall on the instability of shallow landslides was determied in Xining City in order to provide a basis for the monitoring, early warning and prevention of rainfall-type shallow landslide disasters in Xining City. [Methods] The H7 landslide of Nanchuan East Road in Xining City, Qinghai Province was observed and investigated by using space-air-ground observation technology. Based on the fluid-solid coupling principle and unsaturated soil strength theory, hydraulic coupling numerical simulation was carried out to obtain the evolution of porewater pressure, stress, displacement, and plastic zone distribution of the slope under the action of rainfall. The intensity reduction method was used to calculate the slope safety factor under different rainfall durations. [Results] ① The overall landslide form of the H7 landslide on Nanchuan East Road was a long strip, which was a tractor-push landslide. The movement mode was manifested as unstable traction at the slope foot, deformation and sliding in the middle of the slope, and unstable pushing at the top of the slope. ② Rainwater infiltration caused soil saturation to rise, matric suction to dissipate, effective stress to decrease, and shear strength to weaken, resulting in the slope sliding force to increase and the anti-sliding force to decrease, thereby inducing the landslide stability of Nanchuan East Road to continue to decline. ③ After 72 h of simulated rainfall, a nearly penetrating arc-shaped plastic sliding surface was formed in the shallow soil, and the safety factor of the slope decreased from 1.17 to 1.01, indicating an unstable state of temporary stability-deformation. The maximum horizontal displacement was 6.89 cm at the foot of slope. The maximum vertical displacement was 5.98 cm in the upper part of the slope. [Conclusion] ① Space-air-ground observation technology can effectively support the investigation and evaluation of landslide disasters, and finite element hydraulic coupling numerical simulation has strong applicability and good effect for the study of the stability of rainfall-type landslides. ② The stability of the H7 landslide on Nanchuan East Road will be further reduced under high-intensity continuous rainfall, which will threaten the safety of roads, buildings and residents, therefore attention should be given to the potential landslide risk.

Abstract:[Objective] The ecosystem types in the Taihang Mountain area of Hebei Province were scientifically identified in order to provide a basis for understanding the spatial and temporal distribution pattern of ecosystems in the area and to support ecosystem classification management. [Methods] Based on the classification principle of realms-biomes-ecosystem (RBE) functional groups, a classification system including 3 primary classes, 8 secondary classes and 24 tertiary classes was constructed, and multi-source data was integrated to carry out classification mapping of the ecosystems in the Taihang Mountains area in Hebei Province in 2000 and 2020. The spatio-temporal evolution of ecosystem services was analyzed based on the RUSLE model, the InVEST model, and hot spot analysis. [Results] ① The construction land ecosystem in the Taihang Mountain area increased the most during the past 20 years, mainly coming from the farmland ecosystem. The farmland ecosystem decreased by 61 105.95 hm² and was dominated by rain-fed farmland. Due to the influence of human activities, the areas of rivers and constructed wetlands increased by 5 584.32 hm² and 2 535.66 hm², respectively, while the areas of forest and grassland ecosystems decreased by 0.96% and 8.18%, respectively. The area of the unused land ecosystem decreased by 5 800.68 hm² due to the ecological protection measures instituted in the study area. ② The distribution of ecosystem types affected the overall distribution pattern of ecosystem service values, with high values in the west and low values in the east. The exception was for food supply service values where the distribution was low in the west and high in the east, mainly because farmland was located in the eastern region. ③ The spatial distribution of cold spots and hot spots generally overlapped, but there were still differences. [Conclusion] The classification system proposed in this study is feasible, with a classification accuracy of greater than 80%, which is in line with the trend for ecosystem type changes in the study area. This classification system can provide scientific support for the identification of mountain ecosystem classification and ecosystem protection and restoration policies, thereby promoting the realization of mountain ecological development goals and sustainable development.

Abstract:[Objective] The spatial distribution characteristics and laws of geological disasters were determined at the Huangshui River basin in Qinghai Province, in order to provide data support and a scientific basis for disaster prevention and reduction. [Methods] Geological hazard sites were identified by small baseline subset interferometric synthetic aperture radar (SBAS-InSAR). By combining topographic factors, geological factors, environmental factors, meteorological factors, and human activities, the spatial distribution law of disasters was analyzed, and a logistic regression (LR)-frequency response (FR) model was established and tested. The return probability value was used to evaluate susceptibility. [Results] ① The potential geological disasters distributed in the Huangshui River basin were mainly landslide and collapse, and many kinds of potential geological disasters occurred simultaneously. Landslides and unstable slopes usually developed on slopes with low slope and were accompanied by a large number of tension and shear cracks that were especially obvious in the rainy season, posing a threat to the safety of traffic and residents below the mountain. Landslides and unstable slopes on both sides of river valleys may also block rivers and form barrier lakes, further aggravating disaster risks. Slope collapses mostly developed in the steep mountain walls with relatively loose rock structure or severe weathering. Due to geological fragility coupled with stimulation by natural factors such as rainfall, situations easily develop and result in falling mountain soil and rocks that pose a threat to residential areas and traffic lines below. ② Geological disasters were primarily located in the 2 425—3 650 m elevation area of the study area, and the northeast direction was the slope direction of geological disasters. Normalized difference vegetation index (NDVI) decreased with the increase in geological hazards, increased with the increase of slope, relief, and daily precipitation, and decreased with the increase of distance from the fault. ③ The high-risk and relatively high-risk areas in the Huangshui River basin, covering an area of about 5 937.60 km², accounting for about 38.78% of the total area of the study area, and were mainly concentrated in the south and north border areas of Huangshui River basin, Huangzhong-Datong-Haiyan Junction, and the surrounding slopes of the construction area. ④ The evaluation results were tested. The area under curve (AUC) of the receiver operating characteristic curve (ROC curve) of model prediction performance was 0.787. The FR in the prone area decreased step by step from high to low, and this result was in good agreement with the distribution of actual disaster points. ⑤ Fault core density was the main control factor of geological hazard development in the Huangshui River basin, followed by slope direction, relief degree, and road core density. Section curvature had the least influence on geological hazard development. [Conclusion] ① SBAS-InSAR technology effectively identified potential geological hazards in the Huangshui River basin, and the susceptibility evaluation results obtained by the LR-FR model were reliable. ② The distribution of geological disaster prone areas in the Huangshui Basin had obvious spatial differences, mainly located in the areas with higher elevation, lower vegetation coverage rate, greater rainfall, and close to the fault. Fault core density was the main control factor of geological disaster susceptibility. ③ The geological disasters in the Huangshui Basin were characterized by frequent, sudden, and high risk occurrences that seriously impacted local people’s lives, regional economic development, and the ecological environment. Therefore, the monitoring, early warning, and prevention of these disasters are particularly important.

Abstract:[Objective] The spatial relationship between cultivated lands and construction project distributions was analyzed, and a method for defining the upper thresholds of cultivated land proportions in construction project areas was determined in order to provide references for formulating measures of protecting cultivated land. [Methods] The study was conducted in Shaanxi Province. An index of cultivated land density was constructed based on land change survey data and construction project samples. With the integration of GIS spatial overlaying, geomorphic zoning, and statistical analysis methods, intensity zoning of cultivated lands in Shaanxi Province was presented and the upper thresholds of cultivated land proportions in construction project areas were determined. [Results] Using a method that combined geomorphic zoning with administrative unit revision, and taking the 80% cumulative frequency value as the thresholds, Shaanxi Province was divided into three zones of cultivated land density, including North Shaanxi Loess Plateau-intensive cultivated land, Guanzhong Plain/Qinba Mountain-intensive cultivated land, and other districts (non-intensive cultivated land). The upper thresholds of cultivated land proportions in linear project areas and in planar project areas in the three zones were determined to be 26%, 42%, 20%, and 45%, 80%, 27%, respectively. The proportion of cultivated land in construction projects in the districts of intensive cultivated land was significantly higher than in the districts of non-intensive cultivated land, showing that greater density of cultivated land led to a higher proportion of cultivated land in construction project areas. [Conclusion] By defining the upper threshold of the proportion of cultivated land occupied by construction projects, the cultivated land saving rate can range from 1.2% to 17.9%, which could control 13.9%—22.5% of construction projects against excessive occupation of cultivated land, thereby effectively protecting cultivated land resources.

Abstract:[Objective] The key areas of territorial ecological restoration in Zhengzhou City were identified to provide a scientific reference for the planning of territorial ecological restoration in Zhengzhou City. [Methods] Morphological spatial pattern analysis (MSPA) was used to identify ecological source areas, to extract ecological corridors, and to identify key areas for ecological restoration through landscape connectivity assessment and circuit theory, and finally to construct an ecological network security pattern. [Results] There were a total of 37 ecological source areas in Zhengzhou City, covering a total area of 983.29 km², with a distribution pattern characterized as more in the west and less in the east, with a band-like agglomeration in the north-south direction. A total of 85 ecological corridors were extracted in Zhengzhou City, with lengths ranging from 0.11 to 47.92 km, totaling 689.50 km. Among these, there were 19 key ecological corridors, 29 important ecological corridors, and 37 general ecological corridors. Fifty-five ecological pinch points were identified, with a total area of 2.78 km², mainly concentrated in the southwest part of Zhengzhou City. The locations of these pinch points had less resistance, and the main land use types were forests, grasslands, and water bodies. Three levels of obstacle points were classified based on cumulative current values, with a total area of 1 054.31 km², accounting for 14.16% of the study area. These obstacle points were mainly located in urban areas around major transportation roads in Dengfeng City and Xinmi City. Considering the natural and social status of the study area, a “one belt, one ring, two zones, four groups, and multiple points” ecological network security pattern was proposed. [Conclusion] The following strategies for ecological restoration were proposed for the identified ecological pinch points and obstacle points: the ecological pinch point areas have relatively good ecological environments, so natural ecological maintenance should be the main focus. The obstacle point areas are mainly construction land with high development intensity and human disturbance, therefore both artificial and natural restoration should be given equal importance.

Abstract:[Objective] The temporal and spatial changes of ecological environment quality in Yunnan Province were analyzed, and ecological restoration priorities were identified to provide scientific basis for the low-carbon sustainable development of the province. [Methods] The spatio-temporal change and spatial correlation of eco-environmental quality in Yunnan Province were determined based on remote sensing environmental indicators (RSEI), and the priority of ecological restoration in Yunnan Province was identified by combining these results with regional ecosystem carbon reserves and an ecological protection red line. [Results] ① The average value of RSEI in Yunnan Province showed an S-shaped trend over the past 22 years, with 2005 and 2011 being the inflection points of increasing and decreasing RSEI, respectively. ② From 2000 to 2022, the spatial eco-environmental quality was characterized as “high in the west and low in the east”. The ecological environmental quality in the western region was good, while the ecological environmental quality in the central urban agglomeration and the eastern karst region was poor. ③ From 2000 to 2005, the ecological environmental quality became better under the influence of the policy of returning farmland to forests. From 2005 to 2011, the ecological environmental quality decreased significantly due to drought and the drastic expansion of construction land. 2011—2016 was a period of recovery after drought. Except for the areas with rapid urbanization in Central China, the ecological environmental quality in other areas gradually recovered. Due to the influence of national policies from 2016 to 2022, the ecological environmental quality was further improved. ④ The ecological environmental quality of Yunnan Province showed obvious spatial global and local autocorrelation; ⑤ The carbon reserves of Yunnan Province initially increased and then decreased from 2000 to 2022, and the total carbon reserves decreased by 2.38×10⁷ t in 22 years. Carbon reserves showed a zonal distribution characterized as “high in the north and south, and low in the central region”. ⑥ The high priority areas for ecological restoration in Yunnan Province were mainly located in the north and east, accounting for about 18.08% of the total area, while the priority and the medium priority areas for ecological restoration were more widely distributed, accounting for about 70.17% of the total area. The general priority areas for ecological restoration were mainly located in Pu’er City and other places, accounting for about 11.76% of the total area. [Conclusion] The ecological environmental quality of Yunnan Province exhibited distinct patterns in time and space from 2000 to 2022. Based on these results, the ecological restoration area should be divided, and the ecological environment should be controlled according to local conditions in order to promote ecological and sustainable low-carbon development in Yunnan Province.

Abstract:[Objective] The intensity of soil erosion and its spatial and temporal variation in the Yarlung Zangbo, Nyangqu and Lhasa rivers (referred as “YNL rivers”) area of Xizang Autonomous Region were analyzed in order to provide a scientific basis for soil erosion control and ecological management in the area. [Methods] Rainfall, digital elevation model (DEM), soil, vegetation, and land cover data were acquired and used with the Revised Universal Soil Loss Equation (RUSLE) and Geographic Information System (GIS) to estimate the soil erosion modulus in the study area in 1995, 2005, 2015, and 2020, and to classify the intensity of soil erosion. By analyzing the spatial and temporal variation characteristics of soil erosion intensity in the YNL rivers area, the variation pattern of soil and water loss area was determined. [Results] ① The average soil erosion modulus in the YNL rivers area was 30.35 t/(hm²·a). The modulus initially increased and then decreased over time. The area of decreasing soil erosion modulus increased year by year. ② The intensity of soil erosion in the study area tended to be higher in the west and lower in the east. Soil erosion intensity was mainly classified as mild and slight, with the area of these two classifications accounting for 70% or more of the total area. The transfer of soil erosion area between different classifications was mainly from moderate erosion to mild erosion. ③ The proportion of soil erosion area in the watershed showed an overall decreasing trend over time, with Xietongmen and Lazi County being the areas with higher erosion risk. [Conclusion] Soil erosion in the YNL rivers area had strong spatial and temporal variation. The central region had a higher risk of soil erosion, and soil and water conservation research and practices are urgently needed for that region.

Abstract:[Objective] The mechanism of human activities affecting vegetation cover change in the Yarlung Zangbo River, Nyangqu River and Lhasa River (referred as “YNL rivers”) area of Xizang Autonomous Region was analyzed in order to provide an important theoretical basis and scientific guidance for the implementation of integrated protection and restoration projects of mountain, water, forest, farmland, lake, grass, sand, and ice in the area. [Methods] Normalized vegetation index (NDVI), land use data, ecological engineering data, and meteorological data from 2000 to 2020 were used with GIS technology, residual analysis, slope trend analysis, and the M-K test to determine the influence mechanism of human activities on temporal and spatial changes of vegetation cover in YNL rivers area. [Results] ① From 2000 to 2020, NDVI of vegetation in the study area showed an overall increasing trend, but showed a significant spatial difference. The increased area of NDVI was mainly concentrated on both sides of the river valley. ② From 2000 to 2020, the positive impact of human activities on NDVI was mainly concentrated in the valley areas of the YNL rivers, while the negative impact was mainly located in Lhasa and its surrounding areas, the distribution was less, and the positive influences was dominant. ③ Different land use types had different degrees of influence on vegetation cover change. Grassland and scrub ecosystems contributed the most to NDVI changes, reaching 92.8% in total. The urban and forest ecosystem areas increased sharply, and the increase in area of the urban ecosystem was mainly transferred from farmland and grassland ecosystems, while the forest and scrub ecosystems were mainly transferred from grassland and desert ecosystems. ④ Ecologically engineered forest was one of the main reasons for the increase in NDVI in the study area. The area change of ecologically engineered forest was positively correlated with the rate of change of NDVI and the residual change rate. The ecologically engineered forest can better explain the residual change rate. [Conclusion] Human activity is an important contributing factor to vegetation cover change in YNL rivers area of Xizang, and appropriate ecological engineering plays an important role in vegetation restoration.

Abstract:[Objective] The spatiotemporal variation characteristics of chemical fertilizer use in the Yellow River basin and its relationship with grain production were analyzed in order to provide a theoretical basis for the control of chemical fertilizer application in the basin. [Methods] Fertilizer application and grain yield data in the Yellow River basin from 2000 to 2021 were used with spatial autocorrelation analysis, kernel density analysis, and ellipse of standard deviation to analyze the temporal and spatial variation characteristics of fertilizer use in the Yellow River basin, and to explore the relationship between fertilizer use and grain yield. [Results] From 2000 to 2021, grain yield in the Yellow River basin has increased by 49.55%, which was greater than the growth rate of chemical fertilizer application (24.87%). After 2013, chemical fertilizer applications in the basin began to fluctuate and decrease, while grain yield still maintained a growth trend. The efficiency of fertilizer application has significantly improved. During the past 22 years, the regional agglomeration trend of chemical fertilizer application in the Yellow River basin has been continuously weakening. The amount of chemical fertilizer use in the Yellow River basin has a certain degree of spatial imbalance, with hot areas mainly concentrated in Henan and Shandong Province, and cold areas concentrated in Qinghai and Gansu Province. During the past 22 years, the number of hot areas of chemical fertilizer use in the Yellow River basin has decreased, high-value aggregation areas have moved westward, and cold areas have increased. During the past 22 years, the use of chemical fertilizers in the upper, middle, and lower reaches of the Yellow River basin has increased by 46.52%, 38.68%, and 9.5%, respectively. The rapid growth of chemical fertilizer use in the western region has moved the center of gravity of chemical fertilizer use in the basin 57.40 km to the northwest. During the past 22 years, the center of gravity of grain production in the Yellow River basin has shifted 22.06 km to the northwest, and it has tended to separate from the center of gravity of fertilizer use. [Conclusion] The action of reducing chemical fertilizer use and increasing fertilizer use efficiency in the Yellow River basin has achieved significant results, but the overall intensity of chemical fertilizer use still exceeds the standard. Therefore, it will still be necessary to reduce chemical fertilizer use in the future.

Abstract:[Objective] The vegetation dynamics and driving factors of change in the Upper White Nile River region in the 21st century were determied in order to provide scientific guidance for the formulation and adjustment of production activities and environmental policies in the region. [Methods] The study was conducted in the Upper White Nile River region. Precipitation, temperature, and population data were analyzed by trend analysis, partial correlation analysis, and the residual trend method to determine the spatial differences in vegetation (NDVI) changes and their dominant factors in the region from 2000 to 2020. [Results] The average NDVI in the Upper White Nile River region increased at a rate of 0.105/10 a. Temperature change had a stronger impact on NDVI than precipitation. Overall, human activities had a negative impact on vegetation, but this negative impact gradually weakened over time. Shrubland was the most vulnerable of the five land cover types under the background of climate change and human activity changes (with small positive impacts and large negative impacts). Human activities mainly dominated vegetation changes in 15.01% of the land area within the watershed, while climate change dominated 84.99% of the land area. [Conclusion] Although vegetation in the basin showed an overall increasing trend, vegetation degradation had occurred in some areas, especially due to urban expansion and disturbance of farmland cultivation that have caused damage to vegetation. Local vegetation monitoring and management should be done effectively, so as to increase food production and tourism income.

Abstract:[Objective] The morphological spatial distribution characteristics of landscape patterns at peak-cluster depressions in rocky desertification areas were determined in order to provide theoretical reference and guidance for revealing the dynamic changes in landscape pattern and ecological protection of peak-cluster depression rocky desertification areas. [Methods] Morphological spatial pattern analysis (MSPA) was used to identify, process, and classify rocky desertification landscapes in order to obtain seven non-overlapping landscape types such as core and loop lines. Landscape dynamics, landscape pattern index, landscape transfer matrix, and hotspot analysis were applied to determine the morphological spatiotemporal evolution characteristics of landscape patterns in peak-cluster depression rocky desertification areas. [Results] ① In 2000, the morphological landscape types were the most widely distributed (190.60 km²), and in 2022, they were the least distributed (147.32 km²). Among the morphological landscape types, the core was the main landscape type in the study area, with a maximum area of 121.62 km² in 2000 and a minimum area of 76.05 km² in 2022, mainly located in the northwest and southern regions of the study area. The area of isolated islands was the smallest among the morphological landscape types, with a minimum of 1.12 km² in 1990 and a maximum of 3.07 km² in 2022. Landscape types such as isolated islands and branches were scattered among various cores. ② The spatial distribution of morphological landscapes in the research area tended to be dispersed, and the diversity, complexity, and fragmentation of morphological landscapes increased. During the research period, the single dynamic degrees of morphological landscape types were 0.10, -0.18, and -2.13, respectively, indicating a shrinking trend in morphological landscape area. The development of morphological landscape types was most intense from 1990 to 2000, and the development was most gentle from 2000 to 2010. ③ The main direction of morphological landscape type transfer was the transfer of the core landscape type to the edge and pore landscape types. Overall, the main direction of morphological landscape transfer was the transfer of the morphological landscape to the background, and the amount of background transfer in was greater than the amount of transfer out. High-high agglomeration areas showed a trend of expansion towards Runhe, Laojie, and Anle Village, while low-low agglomeration areas showed a trend of expansion towards Sanguang and Laojie Village. [Conclusion] The main monitoring indicators for disaster chain early warning include cumulative rainfall, duration of rainfall, changes in moisture content, and on-site monitoring of slope deformation development. These monitoring parameters are influenced by various factors such as rainfall conditions, soil properties, slope angle, and external dynamic conditions. Therefore, in practical applications, it is necessary to comprehensively consider these factors.

Abstract:[Objective] The long-term vegetation growth status and driving mechanism in the Baiyangdian watershed were assessed in order to provide theoretical support for further protection of the ecological environmental quality in the Xiongan New Area. [Methods] Based on the net primary productivity (NPP) data of NASA MOD17A3H from 2007 to 2020, we used trend analysis, coefficient of variation, Hurst index, and geographical detector to investigate the spatial and temporal variability of vegetation NPP, change trends, and driving factors in the Baiyangdian basin. [Results] ① The mean annual NPP values for vegetation in the Baiyangdian basin varied from 217.1 to 357.6 g/(m²·a), with a spatial distribution pattern of higher in the northwestern mountainous areas and lower in the southeastern plains; ② More than 80% of the vegetation NPP in the study area had obvious fluctuations, with the strongest fluctuations in the northwestern mountainous areas and the southeastern plains; ③The vast majority of vegetation NPP tended to increase over the years, and gradually transitioned from a non-significant to a significant increase from southeast to northwest; ④ Within the study area, the north-western region was a reverse persistence area with Hurst index less than 0.5. Future vegetation NPP may have the problem of slowing down the increasing trend. The southwestern region was a positive persistence area with a favorable trend of future changes; ⑤ The dominant drivers of vegetation NPP spatial differentiation in the study area were temperature, population, tertiary industry, etc. The influence of the two-factor interaction was significantly higher than that of a single factor, with the strongest interaction between precipitation and temperature. [Conclusions] During 2007—2020, the vegetation NPP in the Baiyangdian Basin has gradually increased. Although temperature was the main driving factor affecting the spatial differentiation of NPP, the role played by social factors has been gradually increasing.

Abstract:[Objective] The desertification status and its driving factors in Gansu Province were analyzed in order to provide a scientific basis for the comprehensive prevention and control of desertification and the promotion of ecological projects such as the “Three Norths” shelterbelt program. [Methods] Trend analysis and spatial autocorrelation analysis were used to characterize the spatial and temporal distribution of desertification in Gansu Province from 2000 to 2022, and geographically and temporally weighted regression was used to analyze the influencing factors. [Results] ① The overall desertification in Gansu Province was characterized as “desertification in the northwest and green in the southeast”. The northwest region was affected by both wind erosion and salinization, and exhibited the most serious desertification, which gradually decreased towards the southeast. The central region was affected by soil and water loss, and had a serious degree of desertification, while the south region had a less serious degree of desertification. The degree of desertification in Gansu Province gradually decreased during the 23-year study period, and the amount of decrease was greater in the southern region than in the northern region. ② In terms of spatial autocorrelation, desertification in Gansu Province was mainly characterized by aggregation, i. e., the degree of desertification showed obvious positive spatial correlation. ③ Increased precipitation was most beneficial in mitigating desertification and had a greater impact in the northwest than in the southeast, while wind speed and population exacerbated desertification. Desertification was exacerbated by warmer temperatures in the southwest and vice versa in the rest of the region. [Conclusion] From 2000 to 2022, desertification in Gansu Province showed an improving trend, while desertification in the northwestern part of the province was still serious. There was obvious spatial and temporal heterogeneity in the drivers of desertification in Gansu Province, and the most important factor affecting desertification was precipitation.

Abstract:[Objective] The spatial and temporal evolution characteristics of land use patterns and habitat quality in Zhengzhou City were determined and future development trends were predicted in order to provide a theoretical reference for regional ecological conservation practices and sustainable development. [Methods] The PLUS model and InVEST model were combined with ArcGIS spatial analysis and the geo-spectrum information method to analyze land use changes in Zhengzhou City from 2000 to 2020, and to simulate the spatial distribution pattern under a baseline scenario and an ecological protection scenario in 2030. The spatial and temporal evolution laws of habitat quality and the migration status were then determined at the pixel scale. [Results] ① From 2000 to 2020, cultivated land and construction land were the main land use types in Zhengzhou City. Over the past 20 years, the area of construction land increased sharply by 15.76%, coming mainly from cultivated land. ② The PLUS model was applicable in Zhengzhou City. Compared with the baseline scenario, the expansion of construction land was limited, and the total amount of ecological land increased under the ecological protection scenario, which could provide a reference for promoting ecological construction in the study area. ③ Habitat quality degraded continuously, with significant spatial distribution differences, from 2000 to 2020. High habitat quality areas were consistently located in Gongyi and Dengfeng City, and low and medium-low map units transferred to each other most frequently. ④ In 2030, the pattern of “higher in the west and lower in the east” will continue. Under the ecological protection scenario, habitat quality was characterized by “decrease in low values and increase in high values”, and the transfer rate to the high and medium-high grades increased to 14.44%, showing a stable and positive development trend compared with the baseline scenario. [Conclusion] The spatial and temporal distribution of habitat quality in Zhengzhou City was closely related to land use changes. The study area should focus on the rational layout of national spatial structure, enhance the efficiency of land use, and improve the quality and stability of ecosystems in the future.

Abstract:[Objective] The spatiotemporal changes of ecosystem service value (ESV) during the development and construction of Meizhou Island (a ‘cultural’, ‘pilgrimage’, and ‘tourism’ island) during 2000—2020 were analyzed in order to provide a scientific reference for the formulation of land use planning and ecological construction for the tourism area of the island. [Methods] The global 30 m fine land cover dynamic monitoring data covering Meizhou Island from 1985 to 2020 were used as the data source, and ArcGIS technology was used to extract the land use data for 2000, 2005, 2010, 2015, and 2020 in the study area. The land use changes on Meizhou Island during the recent 20 years was revealed through land use dynamics, land use transfer matrix, and ecological contribution rate. The value equivalent method was used to estimate ESV for Meizhou Island. [Results] ① From 2000—2020, the land use types on Meizhou Island were mainly construction land and cultivated land. Land use area changes were mainly manifested as increases in construction land and wetland, and decreases in cultivated land and forest land. The land use transfer was reflected in the mutual flow among forest land-cultivated land-construction land-water area, and the encroachment of construction land on cultivated land and forest land; ② During the study period, the ESV of Meizhou Island decreased by 12.526 9 million yuan, of which forest land and cultivated land were the main contributing factors of ESV for Meizhou Island. The increases of wetland and water area were the main influencing factors of the increase of ESV; ③ The values of each individual ecosystem service function followed the order of regulation service＞support service＞supply service＞cultural service; ④ The spatial distribution of ESV showed a pattern of ‘lower in the middle and higher on the periphery’, and the distribution of high value areas overlapped highly with that of forest land. Low ESV areas were concentrated in the construction land. [Conclusion] Forest and cultivated land were the main contributors of ESV on Meizhou Island. Regulation service contributed the most to ESV. Therefore, during the development and construction process, we should increase the utilization efficiency of construction land and strengthen the protection of forest land and cultivated land.

Abstract:[Objective] The spatiotemporal characteristics and main driving factors of water supply and demand for water conservation services in a river basin were explored in order to provide a scientific basis and reference for water resource management and optimal allocation, ecological security, and protection. [Methods] The supply and demand of water conservation services in the Raohe River basin study area were quantitatively evaluated based on the InVEST model and multi-source data. A matching spatial relationship between supply and demand of water conservation services was obtained according to the supply and demand index, and the main driving factors of spatial heterogeneity of the supply and demand relationship of water conservation services were further explored by using geographic detectors. [Results] ① From 2005 to 2020, both the supply and demand of water conservation services showed a trend of first increasing and then decreasing, and the water conservation capacity of different land use types had significant differences, among which the water conservation capacities of forest land and grassland were significantly higher than those of cultivated land and urban and rural industrial and mining land. ② The spatial distribution of supply and demand of water conservation services had obvious spatial heterogeneity and mismatch characteristics. The matching deficit area of supply and demand of water conservation services was mainly located in Poyang, Wannian County, Leping City, Changjiang, and Zhushan District in the west, while the surplus area was located in Fuliang County in the north, and in Wuyuan County, Dexing City, and Yiyang County in the east. ③ Among the natural factors, annual potential evaportanspiration, elevation and forest coverage rate were the main factors affecting the supply and demand relationship of water conservation services. At the same time, human factors such as the coverage rate of industrial and mining land and cultivated land in urban and rural areas played a leading role. The interaction between natural factors and human factors aggravated the imbalance between supply and demand of water conservation services. [Conclusion] There were challenges in the optimization of supply and demand of water conservation services in the Raohe River basin. In the future, the establishment of an ecological compensation mechanism should be accelerated in this area, the function of forest water conservation should be optimized, the supply of water conservation services should be increased, and the efficiency of water resource utilization should be increased. Efforts should be made to balance supply and demand of regional water conservation services, and to promote the coordinated development of ecological systems and socio-economic systems.

Abstract:[Objective] The spatiotemporal changes and trade-off/synergistic relationships of ecosystem services in an ecological county were analyzed in order to provide a theoretical reference for promoting the construction of national ecological civilization and to realize the coordinated development of ecological protection and social economy. [Methods] This study was conducted at Wuning County of Jiangxi Province. Field-measured data were used with the InVEST model to evaluate four typical ecosystem services from 2000 to 2020: water conservation, soil conservation, carbon storage, and food supply. On this basis, the trade-off and synergistic relationships of ecosystem services and their spatiotemporal changes were determined. [Results] ① From 2000 to 2020, the average annual water conservation per grid unit at Wuning County increased from 173.14 mm to 283.92 mm, and the average annual food supply per grid unit increased from 3.52 kJ to 5.34 kJ. The soil conservation function showed a fluctuating trend of decreasing, then increasing, and then decreasing. Over the past 20 years, the soil conservation function decreased by 15.71%, while the carbon storage function showed a weak growth trend. ② The forest land at Southern and Northern Wuning County was a high value area of water conservation, soil conservation, and carbon storage. The water areas, construction land, and unused land were the low value areas for water conservation, soil conservation, and carbon storage. Forest land, and farmland were the key land use types for the development of ecosystem service functions. ③ Water conservation, soil conservation, and carbon storage in Wuning County were synergistically related, but the relationships between food supply and the other three ecosystem services were trade-off relationships. The synergies of “high-high” and “low-low” agglomeration were mainly located in high-altitude forest land and water areas, while the trade-off relationships of “high-low” and “low-high” agglomeration were mainly located in farmland. [Conclusion] During 2000—2020, the overall ecosystem service function of Wuning County has shown an upward trend, and the conversion of ecological regulation service functions into resource values should be emphasized in the future.

Abstract:[Objective] The spatial and temporal evolution characteristics of habitat quality and the spatial mechanism of influencing factors in Anhui Province were analyzed in order to provide a basis for improving the ecological management ability and sustainable development ability of the study area. [Methods] The InVEST model was used to analyze the spatial and temporal pattern evolution of habitat quality in Anhui Province from 2000 to 2020. A multi-scale geographical weighted regression (MGWR) model was used to analyze the spatial mechanisms of natural, socio-economic, landscape, and other factors on habitat quality. [Results] ① Cultivated land was always the dominant landscape in Anhui Province from 2000 to 2020, and landscape transformation in the region mainly occurred between cultivated land, forest land, and construction land. The expansion of the landscape elements of construction land was the most obvious. With the increase of disturbance degree of human activities, the landscape pattern of Anhui Province was evolving towards fragmentation and complexity. ② From 2000 to 2020, the average value of habitat quality in Anhui Province decreased by 0.016, showing a slight degradation trend on the whole. The habitat quality in the region was mainly poor (0.2~0.4), and the two periods accounted for more than 40% of the data. There were obvious spatial differences in the habitat quality of Anhui Province, showing a spatial pattern of “higher in the south and lower in the north”. ③ According to the regression results of the MGWR model, rainfall and normalized vegetation index had significant positive effects on the habitat quality of Anhui Province, and the positive proportion of the regression coefficients in the two periods was greater than 80%, and further expanded with time. In terms of the spatial pattern, the regression coefficient of Southern Anhui Province was larger than that of Northern Anhui Province. Population density and GDP per unit area had significant negative effects on habitat quality in Anhui Province. The negative ratio of regression coefficients in both periods was greater than 90%, and the regression coefficient in Northern Anhui Province was larger than in Southern Anhui Province. The maximum patch index and the evenness index had positive and negative bidirectional effects on the habitat quality in Anhui Province. With the development of fragmentation and complexity of the landscape pattern in Anhui Province, the negative proportion of the regression coefficient further expanded. [Conclusion] The spatial pattern of habitat quality in Anhui Province presented a certain pattern. On this basis, combined with the analysis results of influencing factors, differentiated protection policies should be formulated to manage the ecological environment according to local conditions in order to improve the sustainable development ability of Anhui Province and to achieve the goal of harmonious coexistence between man and nature.

Abstract:[Objective] The spatial evolution of the productional-living-ecological space and the identification and measurement of land use relative conflict at Nanchang County of Nanchang City, Jiangxi Provonce from 2000 to 2020 were studied in order to provide a theoretical and practical reference for optimizing the pattern of territorial development and to achieve sustainable development of the social economy. [Methods] Based on three periods of remote sensing images and land use and land cover data in 2000, 2010, and 2020, with the productional-living-ecological space as the research basis, the remote sensing ecological index (RSEI) and landscape pattern index were used to construct a land use relative conflict measurement model. The temporal and spatial evolution patterns of land use relative conflict were analyzed by use of a transfer matrix and ArcGIS visualization. [Results] ① From 2000 to 2020, due to urban expansion and the influence of human activities, the living-productional space in Nanchang County expanded sharply, and the area of production-ecological space and ecological space decreased year by year. ② From 2000 to 2020, the mean value of RSEI decreased in Nanchang County, the overall quality of the ecological environment gradually decreased, and there was an ongoing expansion of the ecological environment degradation region. ③ From 2000 to 2020, the total area of land use absolute conflicts continued to increase, and from 2000—2010 to 2010—2020, the total area of land use relative conflicts decreased slightly. ④ From 2000 to 2020, the out-of-control areas of land use absolute conflicts were mainly located in the central urban area, and continuously expanded outward with the development of urbanization. From 2000—2010 to 2010—2020, the medium and high conflict areas of land use relative conflict shifted from the central urban area to the periphery, mostly in urban expansion areas during the last ten years. [Conclusion] In Nanchang County, the productional-living-ecological space has undergone a significant transformation. The quality of the ecological environment has declined. The absolute and relative land use conflicts have grown. Thus, strategies such as closely adhering to the red line of cultivated land protection, improving the ecological environment, and optimizing territorial spatial layout should be put into practice in order to optimize land use conflicts.

Abstract:[Objective] The spatiotemporal pattern evolution and driving factors of agricultural grey water footprint efficiency were explored in order to provide a scientific reference for promoting agricultural water conservation and comprehensive water pollution control, and high-quality agricultural development in the Yellow River Basin. [Methods] A grey water footprint model, the Theil index, and the log-average Dietscher index were used to estimate the efficiency of agricultural grey water footprint for nine provinces in the Yellow River basin from 2000 to 2021, and the spatial-temporal evolution pattern and driving factors were discussed. [Results] ① The agricultural grey water footprint efficiency during 2000—2021 in the Yellow River basin showed an overall upward trend over time, with an average annual efficiency of 0.235 8 yuan/m³. Inner Mongolia had the highest efficiency (0.467 0 yuan/m³), and Qinghai had the lowest efficiency (0.026 3 yuan/m³). ② The annual average contribution rate of the regional gap in agricultural grey water footprint efficiency was 80.11%, and the annual contribution rate of the upstream gap was 75%, which was the main reason for the large gap in agricultural grey water footprint efficiency in the Yellow River basin. ③ The total effect of agricultural grey water footprint efficiency was 0.202 4 yuan/m³, and the cultivated land resource effect and agricultural environment effect were the main factors in promoting and inhibiting the agricultural grey water footprint efficiency, with contribution values of 0.442 7 yuan/m³ and -0.4406 yuan/m³, respectively. ④ The driving effect of agricultural grey water footprint efficiency in the Yellow River basin can be divided into four models. Different models have different ways of improving agricultural grey water footprint efficiency in different regions. [Conclusion] The nine provinces in the Yellow River basin should adopt different development strategies according to local conditions, optimize the agricultural structure, reduce the intensive use of fertilizers and pesticides, strengthen agricultural water management, and improve agricultural grey water footprint efficiency.

Abstract:[Objective] The level of grassland carrying capacity affects the sustainability of grassland utilization and the security of grassland ecosystems. The carrying capacity of grassland resources in Xilingol League, Inner Mongolia (an important ecological barrier in the north) was analyed in order to provide a scientific basis for the regional ecological security and sustainable use of grassland and the construction of ecological civilization. [Methods] We analyzed and evaluated the status of grassland resource carrying capacity, ecological deficit (ED)/remainder (ER), and ecological pressure index of Xilingol League of Inner Mongolia based on a three-dimensional ecological footprint model. We used land use and other relevant data in 2013, 2015, 2018, and 2020. [Results] ① The ecological footprint continued to be higher than the ecological carrying capacity. The total ecological footprint and total ecological carrying capacity showed a trend of first increasing and then decreasing, decreasing by 2.76% and 7.35%, respectively, over 7 years. The change rates of per capita ecological footprint and per capita carrying capacity over 7 years were -9.62% and -13.19%, respectively. The ecological footprint decreased from east to west, and the ecological carrying capacity in the east and north was higher than that in the west and south. ② The ecological footprint depth first increased and then decreased, with an overall increase of 4.95%, which was greater than 1. The grassland ecosystem remained in an ecological deficit state for many years, indicating that the grassland ecosystem was unsustainable and unhealthy. ③ The results of ecological profit and loss and ecological pressure index reflecting the ecological security of grassland showed that ER/ED was less than 0 and the ecological pressure index was greater than 1 in the study area during the four periods of the study. The ecological carrying capacity of grassland has been continuously overloaded for many years, and the ecological security and stability have continued to decrease. [Conclusion] The arid and semi-arid geographic location of Xilingol League and its resource endowment, combined with high-intensity human economic and social activities, have led to a reduction in the ecological carrying capacity of the grasslands of Xilingol League, and the ecology of this area is in an extremely insecure state.

Abstract:The characteristics of spatial and temporal changes in soil conservation services and the attribution of spatial heterogeneity in the Qilian Mountains were explored, in order to provide scientific reference for the ecological protection and sustainable development of the region. [Methods] Based on the four periods of land use data from 2005 to 2020, combined with topographic, soil and meteorological data, we used the InVEST model and geoprobe method to simulate the soil conservation service, explore the spatial and temporal characteristics of soil conservation and its value, and attribute its spatial heterogeneity. [Results] ①The soil conservation volume in Qilian Mountains area from 2005 to 2020 ranged from 5.02×10⁹ t to 7.89×10⁹ t, with a decreasing trend; the spatial distribution of soil conservation volume was high in the southeast and low in the northwest, and the high value areas were concentrated in the east side of the Qinghai Lake and the Qilian Mountains range in the study area. ② different land use types, grassland soil retention of the largest total amount of soil, forest soil retention intensity was the largest. Soil retention intensity with the increase in elevation was first increased and then decreased in the single peak curve, and with the increase in slope was linearly increasing. ③The average annual value of soil conservation services in the study area was 3.912×10¹³ yuan, with the value of soil fertility conservation E₁ as the main value. ④ The results of geographic exploration showed that slope and soil type had the highest explanatory power for the spatial heterogeneity of soil conservation, and the interaction between vegetation cover and soil type had the highest explanatory power. [Conclusion] Slope and soil type jointly affect vegetation cover, and vegetation cover is the dominant factor influencing the spatial heterogeneity of soil conservation services. It is necessary to convert part of the cultivated land into grassland or woodland, increase ecological protection, improve vegetation cover, reduce soil erosion, increase soil conservation capacity, and thus improve the ecological environment.