Abstract:[Objective] The dynamic mechanism of soil erosion on vegetation covered slope was studied in order to provide theoretical support for revealing the mechanism of vegetation covered slope erosion in earth rock mountainous areas of North China. [Methods] Based on the runoff dynamic characteristics of slope and the method of artificial rainfall simulation, the relationships between runoff hydrodynamic characteristics and erosion processes on vegetation covered slopes (Pinus tabuliformis, Platycladus orientalis, Quercus variabilis and Ziziphus jujuba) were explored quantitively. [Results] The Platycladus orientalis covered slopes had the greatest runoff yield amount with mean value of 56.85 L. The Quercus variabilis covered slopes had the greatest sediment yield amount with mean value of 1 189.15 g. Runoff velocities under all 4 kinds vegetation ranged from 0.803±0.213 to 4.276±0.430 m/min. Reynolds number and Froude number increased with the increase of rainfall intensity, and the values varied 7.127～63.630 and 0.177～0.900, respectively. [Conclusion] Vegetation cover on the slope has a good effect of reducing runoff and sediment. The dynamic factors of runoff on slope are closely related to the sediment yield, which is an important factor to predict the process of soil erosion.

Abstract:[Objective] In order to provide a theoretical guidance for the ecological management of plantations, the soil erosion law of young plantations under different forest ground clearing methods were investigated. [Methods] Based on the observation data of runoff plot from 2018 to 2020, the soil erosion laws between two forest ground clearing methods (control burning and no burning) in a clear-cutting site of 30-year-old Pinus massoniana plantation in Southern Guangxi Zhuang Autonomous Region were compared. [Results] ① The impacts of forest ground clearing method on the soil erosion decreased sharply with the increase of forest land restoration after burning. In the first two years after control burning, the amount of soil erosion was significantly higher in the control burning plots than in the no burning plots (p＜0.05). ② Control burning reduced the minimum rainfall for surface runoff, and with the increase of rainfall amount, the soil erosion at burning plots was significantly greater than that at the no burning plots. [Conclusion] In the clear-cutting site of Southern Guangxi Zhuang Autonomous Region, the soil erosion was mainly occurred in the first two years after control burning, thus it is crucial to prevent soil erosion during this period.

Abstract:[Objective] The effects of biological soil crusts (biocrusts) on the hydrodynamic characteristics of slope flow were investigated in order to provide theoretical guidance for the study of biocrusts anti-erosive mechanism in hilly regions of the Loess Plateau. [Methods] The treatments of biocrusts coverage and destruction were set, and the artificial rainfall simulation experiments were conducted in this study. [Results] ① The slope flow of biocrusts coverage and destruction treatments was the laminar jet stream. ②The biocrusts coverage significantly reduced slope velocity, whereas increased shear stress, resistance coefficient, and stream power (p＜0.05). Compared with the bare land, the slope velocity of algal crust and moss crust treatment decreased by 48.74% and 62.24%. The shear force, resistance coefficient, and stream power increased by 130.01% and 308.07%, 703.35% and 2532.01%, 21.16% and 57.43%, respectively. ③ Compared with the bare land, the resistance coefficient was no significant difference after the biocrusts were destroyed, whereas the flow velocity, shear stress, and stream power were significantly higher than the bare land (p＜0.05). The slope velocity, shear stress, and stream power of the algae crust and moss crust treatments increased by 10.84% and 16.46%, 36.8% and 42.44%, 60.8 and 62.14%, respectively. [Conclusion] The biocrusts coverage increased slope flow resistance coefficient and decreased flow velocity. After the biocrusts were destroyed, the slope flow resistance coefficient was no different from the bare land, but the flow velocity increased. Furthermore, the biocrusts coverage and destruction treatment increased shear force and stream power of the slope flow, thereby increasing the runoff erosion energy.

Abstract:[Objective] The effects of ridge tillage patterns on soil erosion at sloping croplands in the black soil region of Northeastern China were analyzed in order to provide scientific guidance for soil erosion control in this region. [Methods] The simulated rainfall experiments were conducted at the sloping croplands with the 5° and 10° slope gradients. The simulated rainfall intensities were 50 and 100 mm/h. This study took the traditional up-and downslope ridge tillage as the control treatment. The ridge tillage patterns included contour ridge tillage, ridge-furrow intervals tillage, up and down slope ridge + bottom contour ridge tillage, and contour ridge + drainage ditch tillage. [Results] Under the experimental conditions, the contour ridge tillage, ridge-furrow intervals tillage, up and down slope ridge + bottom contour ridge tillage, and contour ridge + drainage ditch tillage effectively regulated runoff and decreased soil erosion, compared with control treatment. However, the regulation effect of different ridge tillage patterns on runoff and erosion decreased with the increase of rainfall intensity and slope gradient. For the 5° sloping cropland, the regulation effect of contour ridge tillage treatment on runoff and erosion was the best. The runoff rates and soil erosion rates were stable below 15.0 mm/h and 0.2 kg/(m²·h) . Under the rainfall intensity of the 50 and 100 mm/h, the runoff was reduced 92.3% and 83.9% respectively, and the soil erosion reduced 96.8% and 94.6% respectively, compared with the control treatments. The runoff reduction and soil erosion reduction benefits of ridge-furrow intervals tillage treatment was slightly greater than those of up and down slope ridge + bottom contour ridge tillage treatment at the 5° sloping cropland. For the 10° sloping cropland, the contour ridge tillage treatment showed better soil water storage and soil conservation capacity in the early stage of rainfall events compared with that of the other ridge tillage patterns. However, the ridges were easy to be damaged in the later stage of rainfall events, caused a rapid increase in soil erosion. In contrast, the contour ridge + drainage ditch tillage treatment could store soil and water in the early stage of rainfall events, and better drained away water in the later stage of rainfall events. [Conclusion] As to gentle sloping croplands, the contour ridge tillage and ridge-furrow intervals tillage patterns should be optimized, in the sloping farmland with steep slope, the contour ridge + drainage ditch tillage pattern should be preferred. Therefore, it is suggested to select suitable ridge tillage patterns according to slope gradients and rainfall characteristics.

Abstract:[Objective] The erosion-deposition process of loess slopes under the effects of various influencing factors was studied in order to provide a scientific basis for the rational layout of soil and water conservation measures, and for planning to control and prevent soil and water loss in the loess hilly and gully region of Northern Shaanxi Province. [Methods] The characteristics of erosion-deposition processes on a loess slope under different slope gradients, slope lengths, and 60 mm/h rainfall intensity were studied using an indoor artificial rainfall simulation experiment. [Results] ①The net erosion process mainly occurred before and after reaching the peak value of erosion rate. The erosion rates alternated between positive and negative values during the entire rainfall period, and the erosion process coexisted with the deposition process. ② When the slope was 5°, 10°, and 15°, the erosion per unit area decreased with increasing slope length. There was an obvious deposition process and critical erosion slope length in the 5—10 m slope section. Under the test conditions, the critical slope length of loess slope deposition was in the range of 4—5 m and 5—10 m. ③ Under the gradient of 5° and 15°, during the entire rainfall process, the cumulative erosion per unit area of the 0—5 m slope section was greater than erosion of the 0—10 m slope section, and there was always deposition in the erosion process. On the 10° slope, deposition began to occur about 15 minutes after rainfall. [Conclusion] Slope gradient and slope length are important factors affecting erosion-deposition processes of a loess slope. The sediment concentration of slope runoff and erosion per unit area can be used as important factors to characterize the erosion-deposition characteristics of a loess slope. To control soil and water loss on a slope, soil and water conservation measures that intercept runoff at the middle and upper slope positions should be adopted.

Abstract:[Objective] The physical properties and their internal differentiations, and the mineral compositions and chemical elements of Benggang soil were studied in order to provide a theoretical reference for a better understanding on the benggang erosion processes. [Methods] Taking three typical Benggangs in Deqing County, Guangdong Province as examples, the methods of screening, drying, laser particle size analysis, liquid plastic limit analysis, X-ray diffraction analysis, and X-ray fluorescence spectrometry were used, to measure the basic physical properties, mineral composition and chemical elements in the different landform positions of the Benggang soil. [Results] ① Soil bulk densities of the headwalls were slightly larger than those of the colluvium, gully and diluvial fan. The water contents and limit water content of headwalls and colluvium were greater than those of the gully and diluvial fan. ② The median particle sizes of the soils were headwall ＜ colluvium ＜ gully sediments ＜ diluvium. Grain size distributions of the headwall and colluvium were bimodal, and those of the gully sediments and diluvium were single peak. ③ The mineral composition of the soils was mainly clay mineral Kaolinite, and followed by Quartz and Muscovite. The chemical components contained SiO₂ and Al₂O₃, which were the top two in content. The content of Ti was the highest, and followed by S. [Conclusion] The physical properties of soil in different topographic position of the Benggangs displayed a certain differentiation phenomena from headwall to diluvium, and the hydraulic gravity composite erosion mechanism was the reason for the formation of this internal differentiation. Under strong chemical weathering, the composition of clay minerals was mainly composed of Kaolinite, and there was no obvious element migration and enrichment in the Benggangs.

Abstract:[Objective] The influence of soil physical and chemical properties and root characteristics on soil detachment rate under different mixed herbs and shrubs was explored in order to provide scientific basis for the evaluation of ecological construction effect in the Loess Plateau. [Methods] Typical taproot shrub Caragana korshinskii, fibrous root herb Artemisia gmelinii and taproot herb Agropyron cristatum, and their composite community were selected as research objects, and the undisturbed soil samples were collected. Soil separation experiment was carried out at a slope of 15° with a flow rate of 36 L/min, the separation rate was estimate, and the related root and soil parameters were determined. [Results] The detachment rate of grass shrub combination was 73.58% lower than that of the single herb and shrub, and the erosion reduction effect of Caragana korshinskii and Agropyron cristatum was the strongest. Correlation showed that the main root factors influencing soil detachment rate were root length density and root weight density, the main factor of soil was aggregate content ＞0.25 mm, the root factor was one of the main factors affecting soil separation rate of herbaceous plants. And the soil separation rate under the combination of shrub and grass was dominated by both soil factor and root factor. [Conclusion] Herb-shrub combined root system can effectively improve soil anti-scour ability, among which the combination of root architecture of taproot system and fibrous root system has the strongest effect, and different root architecture combinations have different leading factors affecting soil properties and anti-scour.

Abstract:[Objective] The aboveground biomass distribution variation and competition intensity of wolfberry (Lycium barbarum)-alfalfa (Medicago sativa) intercropping were studied in order to provide a scientific basis for interspecific allocation regulation and sustainable management of forest-grass intercropping. [Methods] Aboveground biomass samples of wolfberry and alfalfa were acquired by the spatial segmentation method. The distribution variation and spatial competition of the aboveground biomass of each component in the intercropping model were quantitatively analyzed. [Results] Under monoculture conditions, the aboveground biomass of wolfberry trees in the horizontal direction was distributed in the range of 0—90 cm from the wolfberry row, and decreased with increasing distance from the wolfberry row. The distribution of above-ground biomass of wolfberry in the horizontal direction at 40—60 cm above the soil surface moved to the direction of the row of wolfberry when intercropped with alfalfa, and the gravity center of the distribution of above-ground biomass of wolfberry moved upward in the vertical direction at 60—80 cm above the soil surface. The competitive ability of alfalfa was stronger than that of wolfberry in the range of 30—90 cm horizontally and 0—60 cm vertically. The competitive ability of alfalfa gradually weakened with increasing distance from the wolfberry row and the soil surface. The interspecific competition intensity of wolfberry-alfalfa intercropping decreased with increasing distance from the wolfberry row. Competition intensity could be divided into three areas: high-intensity competition area, medium-intensity competition area, and low-intensity competition area (0—60, 60—90 cm, and 90—150 cm, respectively). It is recommended that intercropped alfalfa should be planted 60 cm away from the wolfberry row. [Conclusion] Intensive intercropping of forest and grass results in crop biomass migrating and decreasing due to weak competition for aboveground space, thereby inhibiting plant growth. In order to effectively reduce the competition for aboveground space between forests and grasses in forest-grass intercropping, the competition and stress of forages on forest trees should be reduced by appropriately increasing the planting distance between trees and forages, thereby enabling trees to obtain better growth space. Pastures should be grown outside areas of higher competition.

Abstract:[Objective] The distribution characteristics of soil aggregates in typical relocation sites of Shanghai City were analyzed in order to provide technical support for soil afforestation in relocation sites. [Methods] Taking the soils of two typical relocation sites at urban villages and industrial enterprises as the research objects, 27 soil samples of typical relocation sites were collected, and dry-sieving and wet-sieving methods were used to determine soil non-water stable aggregates and water stable aggregates, respectively. And the distribution characteristics of soil aggregates in relocation sites were analyzed through single-factor analysis of variance. The differences of soil aggregates in different relocation sites were analyzed, and the correlations between soil aggregates and the basic physical and chemical properties of soil were analyzed. [Results] The soil non-water stable aggregates were mainly large aggregates with particle size ≥2.0 mm, accounting for 64.9%. Soil water-stable aggregates were dominated by micro-aggregates with particle size ＜ 0.106 mm, accounting for 73.4%. The destruction rate of soil aggregates was 79.8%. Soil non-water stable aggregates (particle size ≥0.25 mm) in the relocation site of urban village were significantly higher than that in the relocation site of industrial enterprises (p＜0.05), but there was no significant difference in water-stable aggregates. The soil aggregate damage rate of industrial enterprises was significantly higher than that in the relocation sites of urban villages (p＜0.05). The soil aggregate damage rate was significantly positively correlated with soil bulk density, while significantly negatively correlated with soil field capacity, total porosity and organic matter (p＜0.01). [Conclusion] The overall soil aggregate structure in the relocation site of the Shanghai City is poor, and the soil aggregate damage rate is high, but the soil aggregate structure and stability of the urban village is better than that of the industrial enterprises. The soil aggregate damage rate is mainly affected by soil bulk density, field capacity, total porosity and organic matter.

Abstract:[Objective] The effects of different vegetation restoration types on soil physical and chemical properties in abandoned land of coal logistics park were explored in order to provide scientific reference for ecological restoration of similar abandoned land. [Methods] This research took soils of 3 typical vegetation restoration types (arbor mixed forest, shrub forest and grassland) as the research object, and the bare land was used as a control, the physical and chemical properties of the soil under different vegetation restoration types were measured, and the differences, correlations and principal components were analyzed. [Results] ① Compared with the bare land, after ten years of restoration of arbor mixed forest, shrub forest and grassland, the total porosity of the soil increased by 115.17%, 62.06%, 7.57% respectively, and the contents of soil water increased by 105.99%, 71.21%, 67.05% respectively, while the soil bulk decreased by 8.98%, 5.13%, 4.85% respectively. ② The content of soil organic matter in arbor mixed forest and shrub forest increased significantly, and grassland promoted the content of alkali-hydrolyzed nitrogen and available potassium significantly. The content of alkali-hydrolyzed nitrogen and available phosphorus showed significant “surface aggregation” in the vertical direction, while the content of available potassium showed a significant deep accumulation. ③ Organic matter showed a significant positive correlated with alkali-hydrolyzed nitrogen, available phosphorus, and capillary porosity (p＜0.05), and alkali-hydrolyzed nitrogen and available phosphorus showed an extremely significantly positively correlation (p＜0.01), that meant, soil organic matter played an important role in improving soil physical and chemical properties and nutrient cycling. [Conclusion] The soil quality of different restoration types showed an order as: arbor mixed forest＞shrub forest＞grassland＞bare land. The planting of arbor mixed forest and shrub forest can effectively improve the physical and chemical properties of soil in the abandoned land of coal logistics park.

Abstract:[Objective] The variation characteristics and sources of five trace elements Mn, Ni, V, As and Cr in subsidence ponds of different ages in typical mining areas in Huainan were studied in order to provide scientific reference and basis for the risk management, trace elements control in subsidence ponds from coal mining subsidence areas. [Methods] The contents of trace elements Mn, Ni, V, As and Cr in the water samples were determined by ICP-MS. The sources of trace elements were evaluated by pearson correlation and principal component analysis. Meanwhile, the health risk assessment model recommended by the United States Environmental Protection Agency (USEPA) was used to assess the health risks of the elements in subsidence ponds. [Results] ① The contents of trace elements Mn, Ni and V in subsidence pond water with different collapse ages were in line with the limits of Chinese surface water environmental quality standards, and the contents of As and Cr met the water quality standards classⅡof China surface water. ② The general trend of trace elements in subsidence water showed as: young mine＞ old mine＞ middle-aged mine. The contents of trace elements in the subsidence decreased with the increasing age of subsidence ponds. ③ The non-carcinogenic health risk of subsidence water of different ages through drinking water intake would not affect human health. While the carcinogenic elements (As, Cr, Ni) in water bodies of different ages, their average annual carcinogenic health risk values for adult and children was within the acceptable range. Among them, the carcinogenic risk value of As in young mine was much higher, which was close to the USEPA limit. [Conclusion] Due to the coal mining activities, the concentrations of trace elements in the subsidence water reaches the maximum values in the initial stage of coal mining. Therefore, it is necessary to control the risk from sensitive trace elements during initial period of coal mining. The health risk caused by trace elements in the water of subsidence ponds decreased with the increasing subsidence age.

Abstract:[Objective] The grain size characteristics and sources of surface sediments in the Eastern Pamir Plateau were analyzed in order to provide a scientific basis for improving the understanding of the sedimentary environment and ecological environment construction in the western plateau of China. [Methods] The particle size characteristics of surface sediments in the Eastern Pamir Plateau were analyzed using a laser particle size analyzer. The influence of remote aeolian sedimentation on the composition of surface sediments was analyzed by use of a backward trajectory model. [Results] The surface sediments in the study area were mainly sand particles. Particle size of the surface sediments decreased with the gradual increase of altitude. It was preliminarily speculated that the surface sediments were mainly lacustrine sediments, and the far-source aeolian settlement was mainly affected by westerly air flow in Central Asia and sand dust particles in the Western Taklimakan Desert. [Conclusion] The Eastern Pamir Plateau is located in a fragile ecological environmental area. Land use planning should be formulated according to local conditions. At the same time, it is necessary to prevent the impact of dust particles on the ecological environment of Central Asia.

Abstract:[Objective] The effects of water content and molecular weight of polyacrylamide (PAM) on shear strength of reconstructed iron tailing sand were analyzed in order to better understand slope stability and ecological restoration of mining areas. [Methods] An indoor shear strength experiment was conducted by reconstructing iron tailing sand. Five reconstruction soil mixing rate treatments of soil (S) and tailings (T) were established: S (0% T), S₃T₁ (25% T), S₁T₁ (50% T), S₁T₃ (75% T) and T (100% T). Treatments also included two water contents (15%, 20%), two molecular weights of PAM (3.00×10⁶ , 6.00×10⁶ Da), and three compaction states (loose, tight, and dense) for each reconstruction pattern. [Results] ① Under the same compaction state, the internal friction angle, cohesion, and shear strength for the five reconstruction patterns all decreased with increasing water content. ② Under the same water content, the internal friction angle, cohesion, and shear strength of the five reconstruction patterns increased with increasing compaction. ③ Addition of PAM effectively improved the shear strength of reconstructed iron tailing sand, and shear strength decreased with increasing molecular weight of PAM. ④ When PAM with a molecular weight of 3.00×10⁶ Da was added into the five reconstruction patterns, the shear strength and water infiltration capacity of S₃T₁ were greater than for the other reconstruction patterns. [Conclusion] The reconstruction pattern of S₃T₁ with a water content of 15% and PAM molecular weight of 3.00×10⁶ Da were conducive to the restoration of the ecological environment in mining areas and to the improvement of the stability of iron tailing sand.

Abstract:[Objective] The effects of vegetation restoration on soil moisture and nutrients were studied, and the type of vegetation restoration that has the best effect on soil water and fertilizer conservation was clarified, in order to provide theoretical basis for the ecological restoration and regional soil erosion control of the feldspathic sandstone area. [Methods] The transition area between exposed feldspathic sandstone and soil-covered feldspathic sandstone in Nuanshui Township, Jungar Banner of Inner Mongolia was selected as the study area, and soils of different artificially restored vegetation and naturally restored grassland in loess-feldspathic sandstone boundary area were taken as the research object. The content of soil water and nutrients were measured, and the effects of different vegetation restoration and soil thickness on the characteristics of moisture and nutrient in the feldspathic sandstone area were analyzed with natural grassland as control. [Results] ① The soil moisture content in the transition zone from exposed feldspathic sandstone to soil-covered feldspathic sandstone was mainly affected by the thickness of loess. The water holding capacity of loess soil was better than that of feldspathic sandstone soil, and nutrient contents were mainly affected by vegetation restoration types. ② The soil indexes in the study area were of medium variation, in which the contents of soil moisture, carbon and nitrogen increased gradually with the increase of soil thickness from north to south, while the distribution of phosphorus was opposite. ③ Compared with natural grassland, the restoration of Hippophae rhamnoides and Pinus tabuliformis has the best effect on improving the content of soil carbon and nitrogen in feldspathic sandstone area. The content of soil organic matter increased by 43.12% and 34.27%, total nitrogen increased by 78.95% and 42.11%, ammonium nitrogen increased by 25.64% and 46.15%, and nitrate nitrogen increased by 69.44% and 42.22%, respectively. Among them, the content of soil moisture under the restoration of Pinus tabuliformis was higher than that of natural grassland by 54.55%, but the soil phosphorus level did not increase after artificial vegetation restoration. [Conclusion] Loess has better water-holding capacity than feldspathic sandstone soil, and the interface between the two has a certain barrier effect on the infiltration of water and the upward loss of water in the lower layer. Therefore, the water-storage and water-retention capacity of the overlying soil can be considered in the improvement of soil moisture in feldspathic sandstone area. During the restoration of artificial vegetation, it is recommended to plant Hippophae rhamnoides and Pinus tabuliformis, which can improve the soil moisture, carbon, and nitrogen content, as they have better water and fertilizer retention capacity.

Abstract:[Objective] The effects of green manure on soil physical properties of dryland winter wheat field were investigated in order to provide scientific basis for its popularization in dry farming area of Loess Plateau. [Methods] Based on a 4-year winter wheat field experiment, the effects of planting Changwu soybean, Sudan grass, soybean/Sudan grass mixture and control with no cover crop (CK) on bulk density, porosity, water holding capacity, and aggregation in the cultivated soil layer at 0—20 cm depth during the harvest of dry winter wheat were studied in the Loess Plateau. [Results] At 0—10 cm depths, compared with CK, Sudan grass and mixture treatment significantly decreased soil bulk density. Soybean, Sudan grass and mixture treatment significantly increased soil capillary porosity, total porosity, saturated water capacity, capillary water holding capacity, the proportion of large aggregates (＞ 5 mm), and aggregate mean weight diameter (MWD) (p＜0.05). At 10—20 cm soil depth, Sudan grass treatment had the higher proportion of large aggregates and MWD than CK. Soil bulk density was negatively correlated with soil organic carbon, while soil total porosity, saturated and capillary water capacity were positively correlated to cover crop biomass and soil organ carbon. [Conclusion] In the Loess Plateau, top soil physical properties can be enhanced by monoculture planting Changwu soybean, Sudan grass, or mixture sowing during summer fallow, especially monoculture of Sudan grass.

Abstract:[Objective] The effects of super-absorbent polymers (SAPs) on physiological properties of cucumber roots and leaves under different drought conditions were studied in order to clarify the internal relationships between plant growth and soil water conditions with SAP applications. [Methods] A pot experiment with varying irrigation amounts was conducted to study the effects of SAPs on physiological properties of cucumber rhizosphere moisture, root morphology, leave chlorophyll fluorescence parameters, and stomatal characteristics were measured under three different water conditions. [Results] ① The growth of cucumber roots was significantly inhibited by the SAP treatments. Compared with the control, total root length, average root diameter, total root volume, root surface area, and root dry weight of SAP treatments were significantly reduced by 3.4%, 24.2%, 62.1%, 41.0%, and 51.6%, respectively, when soil water content was 70% (FC₂) and 55%(FC₃) of field capacity. ③ Effective photosynthetic efficiency (F_v'/F_m') and actual quantum yield 〔Y(Ⅱ)〕 with SAP treatments initially increased and then decreased with increasing drought stress, while non-photochemical quenching (NPQ) showed the opposite change. Especially with FC₂ and FC₃, the photochemical quenching (q_P) values of cucumber leaves were significantly reduced by 5.5% and 9.1%, respectively, compared with the control. ③ The effects of soil water on open stomata number, total stomatal ratio, and stomatal opening of cucumber leaves were greater than the effects of SAPs. [Conclusion] Soil water content was one of the important factors determining whether SAPs can alleviate drought stress of plants. When soil water content was 70% and 55% of field capacity, SAPs aggravated the negative effects of drought stress on cucumber root growth and chlorophyll fluorescence characteristics.

Abstract:[Objective] The ecological environment quality in Alar reclamation area was evaluated with the help of remote sensing ecological index (RSEI), to analyze the changes and driving factors of ecological environment in the study area in recent 30 years, in order to provide scientific reference for the development and ecological protection of Alar reclamation area. [Methods] Landsat TM/ETM⁺/OLI image data in 1990, 2000, 2011 and 2020 were selected to construct RSEI by coupling green index (NDVI), humidity index (WET), dryness index (NDSI) and heat index (LST). The driving factors such as climate, population and economy were considered to explore the dynamic changes of eco-environmental quality in Alar reclamation area. [Results] The average value of RSEI in Alar reclamation area increased from 0.344 to 0.468 during 1990—2020, and the ecological environment quality was generally improved. From 1990 to 2020, the quality of ecological environment in the Alar reclamation area improved mainly in the northern and southern areas. The improved area reached to 1 756.36 km², accounting for 45.92% of the total area. The ecological environment quality was affected by natural factors and socio-economic factors. Changes in the quality of the ecological environment in the Erken area played a leading role. [Conclusion] the ecological environment in Alar reclamation area has been effectively improved in recent 30 years, and the remote sensing ecological index can effectively reflect the changes of ecological environment quality in Alar reclamation area.

Abstract:[Objective] An inspection and management system for check dams was designed with the help of modern smart phones and informatization technology in order to further implement “three responsible persons” management system, and to improve safety management for check dams in the Loess Plateau. [Methods] A WeChat application named “Inspection and Management System for Safe Operation of Check Dam” was designed for smart phone used to assist managers at all levels to inspect and manage check dams. [Results] An information database for check dam projects and a personnel management database for managers were established that allowed managers to carry out inspections and clocking in and out as required. The system can identify safety hazards for check dams, remind managers to describe the problems identified, and upload pictures for reminding higher authorities to propose timely solutions to eliminate safety hazards and to reduce risks. Additionally, an application module was constructed for the smart water application platform. [Conclusion] The designed smart phone application could increase the information level for safety management of check dam projects in the Loess Plateau, shorten the response time for reporting safety hazards to responsible departments so that problems can be solved, and assist management departments at all levels to keep abreast of project risk points in their jurisdiction at any time.

Abstract:[Objective] The factor calculation method of the Chinese soil loss equation (CSLE) were optimized to improve the simulation accuracy of CSLE for a hilly watershed of Shandong Province in order to provide technical support for dynamic monitoring of soil erosion factors in this region. [Methods] The Haoyu small watershed of Zibo City was taken as the research area. Factors in the CSLE model, such as vegetation cover, biological measures, and topographical features, were optimized by combining domestic high-resolution satellite data and UAV low-altitude remote sensing data. The superiority of the optimized soil erosion model factor was verified by comparing with national monitoring data. [Results] ① The factors of rainfall erosion and soil erodibility were consistent with the dynamic monitoring results of soil erosion in Shandong Province. The main soil conservation engineering measures were terraces, for which the factor value for ridge terraces was 0.084 and the factor value for stone ridge terraces was 0.121; the factor value for farming measures in the study area was 0.425. ② The similarity of the slope and length factor frequency curve was 0.91, which can be used for soil erosion calculation; the goodness of fit coefficient (R²) was 0.686 8 for the scale conversion model for vegetation coverage extraction, which can be used for the calculation of vegetation cover and biological measures. ③ The correlation coefficient between the soil erosion data calculated by the optimized model and the soil erosion data monitored by the state was 0.686 8. [Conclusion] The optimized method of factor extraction and calculation in the CSLE model could improve the simulation accuracy of the model, and the soil erosion modulus calculated after factor optimization is more in line with the actual local situation.

Abstract:[Objective] The ecological compensation amount for the bidirectional regulation of water quality and quantity in the Shaanxi area of the Yellow River basin was determined in order to provide a theoretical basis for solving the contradiction of ecological rights distribution in the upper and lower reaches of the Yellow River basin, and will promote equitable development between regions of the basin. [Methods] This study considered the simultaneous factors of cost, value, and rewards and punishments, and established a compensation standard calculation model of water quality and quantity using the water quality improvement coefficient method and the water quantity contribution method based on the basic compensation standard. [Results] The basic compensation standard for ecological compensation in the Yellow River basin of Shaanxi Province was 1.37×10⁹ yuan. The water quality and water volume adjustment values were -5.66×10⁸ yuan and 6.84×10⁸ yuan, respectively. Shaanxi Province received ecological compensation of 1.49×10⁹ yuan for 2018. [Conclusion] Compared with previous calculation models, the calculation results of this model are more in line with the actual situation and more suitable for changes in external environmental factors.

Abstract:[Objective] The influence of water-related structures on the flood routing process before and after structure construction was analyzed to provide scientific supports for the real and efficient calculation of bridge engineering in flood storage and detention areas, and for the effective development of flood control in flood storage areas. [Methods] The Mengwa flood storage area in Fuyang City, Anhui Province was selected as the study area. Based on the latest data of regional topography, hydrological data, and bridge engineering design, the unstructured hydrodynamic model of MIKE 21 was used to simulate the flood evolution process of the Mengwa flood storage area in real time. The influence of bridge construction on flood evolution time, velocity distribution, and water level change in the flood storage and detention area was analyzed. [Results] After the construction of the bridge project, the flood-splitting time near the bridge position was 45 s behind the maximum lag before the construction of the project; the flow rate distribution range of the mainstream area was 0.4 to 0.6 m/s; the local velocity change rate was 7.409%; the maximum elevation value of the water level near the bridge was 0.006 m; and the maximum change rate of the water level was -0.22‰. [Conclusion] Bridge construction delayed the flooding time in the flood storage area, raised the water level near the pier, and changed the distribution of the flow rate near the project. However, the overall impact on the flood storage area was small, and basically did not affect the normal operation of the flood storage area.

Abstract:[Objective] The risk of soil and water loss and such secondary disasters that may exist in the construction of pumped storage power stations was evaluated to screen and analyze the characteristics of the elements involved in order to provide scientific support for improving green and safe construction during the project construction period. [Methods] The analytic hierarchy process method was used combined with the fuzzy comprehensive evaluation method to select eight primary indicators and thirty-four secondary indicators from three dimensions for analysis and assessment. [Results] A risk assessment model of soil and water loss and its secondary disasters during the construction period for a pumped storage power station was constructed, and the risk was divided into five levels. The model was applied to the Jixi pumped storage power station in Anhui Province. The risk level of soil and water loss and its secondary disasters during the construction period for this pumped storage power station was level three, which belongs to the general safety level. The feasibility of the model was verified by comparing results with actual measurements during the construction period. [Conclusion] Site selection for pumped storage power stations could largely determine the risk level of soil and water loss and secondary disasters during the project construction period. Projects with risk level of grade three as evaluated by using method in this study could benefit from improved supervision frequency on the basis of learning from relevant soil and water conservation supervision and risk prevention and control measures. Such actions could avoid soil and water loss occurring from slope sliding and slag sliding as far as possible, and allow for the taking of preventive measures to completely eliminate the occurrence of soil and water loss and related secondary disasters.

Abstract:[Objective] The ecological carrying capacity of Qinghai Province and its cities and prefectures were quantitatively measured to reveal its spatial and temporal evolution characteristics, in order to provide a reference for the sustainable development of Qinghai Province. [Methods] The ecological carrying capacity evaluation index system was constructed using the DPSIR model and considering five factors: driving force, pressure, state, impact, and response. The entropy value method was applied to determine the weight coefficients of the indexes. The TOPSIS model and the obstacle degree model were used to measure and analyze the ecological carrying capacity and the impact factors for Qinghai Province and its cities and prefectures from 2008 to 2019. [Results] Ecological carrying capacity of Qinghai Province and its cities and prefectures increased significantly from 2008 to 2019. Ecological carrying capacity of cities and prefectures in Qinghai Province differed spatially, with the two eastern cities having greater carrying capacity than other regions. The main factors influencing ecological carrying capacity in Qinghai Province from 2008 to 2019 have generally undergone a transformation that follows the pattern of social development-environmental pollution-population pressure and economic growth rate. [Conclusion] The ecological carrying capacity of Qinghai Province has increased significantly during 2008—2019, but the ecological situation remains severe. Policies regarding ecological protection should be actively implemented, the speed of social and economic development should be accelerated, and the ecological carrying capacity of cities and prefectures should be comprehensively improved in order to achieve high-quality sustainable development in Qinghai Province.

Abstract:[Objective] The temporal and spatial changes of the cultivated land resource carrying capacity index of Shaanxi Province from 2010 to 2019 were analyzed, and the cultivated land resource carrying capacity index and human-grain relationship were predicted from 2020 to 2025, in order to provide theoretical reference for territorial spatial planning and cultivated land protection policy in Shaanxi Province. [Methods] Based on the panel data of the statistical yearbook, the research was carried out by using the center of gravity migration model, Geodetector and GM(1,1) model. [Results] ① From 2010 to 2019, the overall grain production, population, and cultivated land carrying capacity of Shaanxi Province increased, while the LCCI (land carrying capacity index) fluctuated slightly and decreased, and the human-grain relationship slightly eased. The LCCI of different administrative region fluctuated greatly, and the time periods of the drastic changes occurred from 2010 to 2011, 2014 to 2015, and 2017 to 2018. ② From 2010 to 2019, there were great regional differences in the LCCI in Shaanxi Province, showing a spatial pattern of high in the south and low in the north. Xi’an City and Yangling Agricultural Hi-tech Industries Demonstration Zone were high-value centers, while Yulin City was a low-value center. From the perspective of zoning, the order of the LCCI was Southern Shaanxi region＞ Guanzhong region＞ Northern Shaanxi region. The center of gravity of the LCCI of Shaanxi Province in the past 10 years was located in Xianyang City, and the overall migration direction was from northeast to southwest, pointing to Xi’an City and Yangling Agricultural Hi-tech Industries Demonstration Zone. There were obvious mutation in the path between 2013—2015 and 2017—2018, which was related to the fluctuation of the LCCI of different administrative regions. ③ The most important factor affecting the temporal and spatial changes of the LCCI in Shaanxi Province was the per capita cultivated land area, with an average explanatory rate of 69.21%. ④ It was predicted that the LCCI of Shaanxi Province would decline slightly from 2020 to 2025, and the spatial pattern would remain high in the south and low in the north. Except for the two low-value centers of Tongchuan City and Weinan City, Yulin City, the human-grain relationship in other administrative regions were more tense. [Conclusion] The human-grain relationship in Shaanxi Province is relatively tense, and the changes in the cultivated LCCI of various administrative regions show volatility and strong spatial heterogeneity. The cultivated LCCI in Shaanxi Province is mainly affected by the area of cultivated land per capita.

Abstract:[Objective] The spatial distribution characteristics of soil erosion was explored, the main influencing factors were identified and quantitative attribution of driving force factors were carried out, in order to guide regional soil erosion control and ecological environment construction. [Methods] Taking the area along the Yangtze River in Jiangsu Province as the research object, based on high-resolution remote sensing images, digital elevation models, and long series of rainfall data, the methods of Chinese soil loess equation (CSLE) and geographic detectors were used to explore the dominant influencing factors and interactions of the spatial variability of soil erosion, to identify areas with high risk of soil erosion. [Results] ① Slope and land use types dominated soil erosion in plain and hilly areas. The soil erosion of tea gardens was dominated by vegetation coverage, and soil erosion of other types of land use was dominated by slope. ② The dominant interaction of soil erosion was slope superimposition of land use types. The dominant interaction factors between tea garden and grassland were slope and vegetation coverage, and the dominant interaction factors for soil erosion of other types were slope and rainfall. ③ High-risk areas of soil erosion in orchards, tea gardens, woodlands and areas disturbed by production and construction activities were located in hilly mountainous areas with slopes＞ 20°, rainfall of 1300～1 400 mm, and high vegetation coverage. [Conclusion] The geo-detector is easy to operate. The results include single factor influence, two factor interaction and risk area analysis. Close attention should be paid to the problems of soil erosion in areas disturbed by production and construction activities and garden plots in Jiangsu Province.

Abstract:[Objective] The protective effect of plants on the slope of an expansive soil was evaluated in order to provide a scientific reference for the selection of protective vegetation on the slope of expansive soils. [Methods] Eight common plants were selected from the herbaceous vegetation in the expansive soil area in Nanning City, Guangxi Zhuang Autonomous Region, and their overall root characteristics and stratified root characteristics were extracted. The four indexes of stratified root characteristics (root length, root surface area, root diameter, and root volume) were calculated. The entropy method was used to assign weights to the four characteristic indexes of the root system, and the advantages and disadvantages of the slope protection effect of vegetation root systems were evaluated comprehensively based on the weight of different characteristic indexes. [Results] The results showed that the root diameter of vegetation ranged from 0.25 mm to 0.55 mm, and there was little change with depth. Root length, root surface area, and root volume in shallow soil of 0—5 cm layer) accounted for 50.0%~85.4% of the entire depth range, and decreased sharply with increasing soil depth. Root length, root surface area, and root volume had obvious advantages over the entire depth range. The weight coefficients of root length, root surface area, root diameter, and root volume were 0.310 0, 0.243 2, 0.165 4, and 0.281 5, respectively. The comprehensive evaluation value was the highest for Bidens pilosa. (0.916), followed by Festuca elata (0.761). The lowest value was observed for Lolium perenne (0.110). [Conclusion] Based on the comprehensive analysis of different index weights, the rating of Bidens pilosa was the highest, and therefore, this species is the most suitable for slope protection in the expansive soil area of Nanning City.

Abstract:[Objective] The susceptibility zoning and meteorological forecast model of highway geological hazards were studied in order to provide a theoretical basis for implementing the meteorological forecast of geological hazards along the highways in Linzhi City, Tebit Autonomous Region. [Methods] Firstly, eight zoning factors, including fault density, soil type, slope, valley density, annual precipitation, land use, bare rock ratio and distance from rivers, were selected in the 15 km buffer zone along the highway in Linzhi City. The coefficients of each zoning factor were determined by the information and logistic regression method, and the zoning model of geological hazard susceptibility was obtained. Secondly, based on the daily precipitation data of the rainfall occurrence day, the first day, the second and and the third day before the landslide hazards, a meteorological forecast model of geological hazards was established by using logistic regression method. [Results] The susceptibility of most areas in the 15 km buffer zone along the highway in Linzhi City was less than 0.4, and the closer to the road, the greater probability of geological hazard susceptibility. The accuracy rate of the model was 85.71%, and the failure rate was 14.29%. [Conclusion] Affected by topography, geomorphology and precipitation data, the prediction results of the established model may deviate from the actual situation, but it can reflect the basic trend.

Abstract:[Objective] The temporal and spatial variation characteristics of vegetation coverage in Sichuan Province from 2009 to 2020 were monitored and analyzed, in order to provide important basic research data for quantitative assessment of the regional ecological environment, and scientific references for urban planning and sustainable urban development. [Methods] Landsat images of Sichuan Province from 2009 to 2020 were acquired from the Google Earth Engine cloud computing platform, and the vegetation coverage area was quantitatively estimated by the binary pixel model. [Results] ① In the 11 years from 2009 to 2020, Sichuan Province was mainly dominated by high and medium high vegetation coverage, accounting for 80% of the province’s area, while the proportion of low and medium low vegetation coverage was less than 10%. ② From the perspective of spatial distribution, the spatial difference of fractional vegetative cover (FVC) in Sichuan Province was obvious. The areas with low FVC were mainly located in the Chengdu Plain Economic Zone and some areas in Western Sichuan Province. ③ From the analysis of spatial change characteristics, FVC in the study area showed a basically stable trend (44.39%) from 2009 to 2020. The area of FVC improvement (30.78%) was larger than that of FVC degradation (24.82%), and the area of obvious degradation accounted for the least proportion (only 4.96% of the province’s area). [Conclusion] On the whole, vegetation coverage in Sichuan Province from 2009 to 2020 was in good condition, mainly with high and medium high vegetation coverage. The vegetation coverage showed a basically stable trend. From 2009 to 2020, the area of Sichuan Province was mainly dominated by high and medium high FVC levels that accounted for 80% of the province’s area, while the area of low and medium low FVC accounted for less than 10% of the area.

Abstract:[Objective] An urban ecological security pattern were constructd to identify the main ecological corridors in order to provide a scientific reference for optimizing the ecological pattern in urban land spatial planning. [Methods] Fuzhou City of Jiangxi Provicne was used as a research area. A minimum cumulative resistance (MCR) model was constructed by selecting various land use factors, soil and water conservation function importance, and ecological sensitivity. The importance of a biodiversity maintenance function, global hydrological analysis, ecological protection red line, and natural protection were used to identify ecological sources using the MCR model and spatial analysis tools in ArcGIS. [Results] ① The overall ecological environment of Fuzhou City was good. The proportion of areas with extremely important soil and water conservation function was 49.97%, mainly concentrated in the central area of Fuzhou City, mainly Lichuan County, Le’an County, Yihuang County, and Nanfeng County. The proportion of extremely important ecological sensitivity was 1.39%; ② The ecological source area was 3 302.34 km², accounting for 17.57%, mainly in the east and southwest parts of Fuzhou City; ③ Based on the ecological elements and topography of the entire region, Fuzhou City presented an ecological security pattern of “one axis, two screens, multiple corridors, and multiple nodes”. [Conclusion] By combining ecological sources, ecological corridors, and ecological nodes, a complete and systematic ecological protection pattern and an open spatial network system can be formed to maintain the ecological security and biodiversity of Fuzhou City.

Abstract:[Objective] The quantity and distribution characteristics of ecological land in the karst area during 2000—2020 were analyzed and the changes in ecological land based on multi-scenario decisions in the future were predicted to seek the optimal scenario and coordinate ecological protection and development, in order to provide a theoretical foundation for the future land space development and protection, ecological space management and regional eco-economic sustainable development of the study area. [Methods] The land use transfer matrix and dynamic degree model was used to analyze the land-use change characteristics at Ningyuan County, Hunan Province. The FLUS (future land use simulation) model was used to simulate and predict the quantity and distribution of ecological land under different scenario decisions in 2030. [Results] ① Cultivated land was mainly concentrated in the central area of Ningyuan County, and the original ecological land of forest land and grassland was mainly distributed in the north, south, and west. Among the natural ecological land in 2020, forest land accounted for 56.69%, grassland for 12.85%, and water area for 0.60%, and semi-artificial ecological land of cultivated land, accounted for 27.80%. ② Under the ecological protection priority scenario, the forest land, grassland, and water area increased by 15.12, 37.35, and 23.67 hm², respectively, compared with those in 2020. ③ The policy had a significant regulating effect on the change of ecological land in the karst area, and socioeconomic development had a significant impact on water area increase. [Conclusion] The proportion of original ecological land in Ningyuan County is as high as 70.14%. The priority scenario of ecological protection ensures that ecological land is not occupied by non-ecological land at the maximum extent. This scenario is suitable for the urban development of Ningyuan County or the similar areas under the goal of building a forest city.

Abstract:[Objective] The coupling relationships and change mechanisms between rural land consolidation projects and rural beautification construction were studied in order to provide a theoretical basis for implementing plans for land consolidation projects in the context of rural beautification construction. [Methods] Eleven rural land consolidation projects at Jingbian County of Shaanxi Province were selected as cases. An evaluation index system for rural land consolidation projects and an evaluation system for rural beautification construction were established. The entropy weight method was used to determine the index weight. The relative coefficient evaluation method was used to process the basic data and to calculate index scores. A correlation analysis curve was determined using Sigmaplot 10.0 software to estimate a regression model in order to explore the coupling relationship between rural land consolidation projects and rural beautification construction. [Results] ① Coupling relationships between economic benefit and village appearance, living standard, rural civilization, and production development followed the order of living standard ＞ production development ＞ rural civilization ＞ village appearance. The coupling relationship between economic benefits and village appearance was not significant; ② Coupling relationships between grain production capacity and village appearance, living standard, rural civilization, and production development followed the order of production development ＞ living standard ＞ rural civilization ＞ village appearance. As grain production capacity increased, village appearance score initially increased, then decreased, and finally increased, but the fluctuation range was narrow (between 50 and 70). The change trend between grain production capacity and both living standard and rural civilization increased with increasing grain production capacity score, and living standard initially decreased and then increased. ③ The coupling relationships between cultivated land grade and village appearance, living standard, rural civilization, and production development followed the order of production development ＞ living standard ＞ rural civilization ＞ village appearance. The relationships between cultivated land grade and village appearance, rural civilization, and production development initially decreased, then increased, and finally decreased. The fluctuation ranges were 50—70, 20—80, and 30—80 points, respectively. The coupling relationship between cultivated land grade and village appearance was the lowest. [Conclusion] Through the analysis of the coupling function curve and the correlation coefficient, it can be concluded that for rural land consolidation, economic benefits, grain production capacity, and cultivated land have good coupling relationships with living standard and production development for the evaluation index of rural beautification construction, followed by the relationship with rural civilization. The coupling relationship with village appearance needs to be further improved to provide new solutions for subsequent land consolidation project innovations and system innovations that will ultimately achieve mutual benefits between the two systems.

Abstract:[Objective] The chemical characteristics of groundwater in Beichuan River basin were analysed, and groundwater quality was evaluated objectively from the perspective of resource attributes of groundwater in order to provide data support for regional groundwater environmental protection. [Methods] 189 sets of groundwater chemical data acquired by hydrogeological surveys in 2019 were selected to analyze the distribution characteristics and sources of groundwater chemical composition in Beichuan River basin. An evaluation method for regional groundwater quality was constructed by assigning different coefficients for water quality type to a single sampling point. [Results] The groundwater chemical distribution of Beichuan River basin exhibited a large spatial variability. HCO₃-type freshwater was widely disturbed in the upstream sections of the hilly mountainous area and the valley plain area , and SO₄^2-, Cl-type brackish and salt water, as well as HCO₃·Cl-Na type freshwater gradually appeared downstream, indicating human activities. Weathered dissolution of carbonate rock and silicate rock controlled the source of groundwater chemical components, but local areas were enriched due to evaporation concentration. Natural background elements such as Al, Fe, and Th were the main influencing indicators that had exceeded the underground water quality standard in the study area, but typical contamination components such as Pb, NO₃^-, and carbon tetrachloride were more obvious in the industrial zone and the population-concentrated area. Under the driving influences of human pollution and naturally high background conditions, the underground water quality in the river valley plain was more complicated. The over-standard ratios of the hilly mountainous region and the valley plain region based on the quantity of sampling points were 57.0% and 27.1% respectively, but these values were reduced to 29.4% and 12.6% according to the new evaluation method proposed in this study. [Conclusion] The impact of human pollution on the chemical components of groundwater was mainly concentrated in middle and lower reaches of the valley plain zone, and chemical components of groundwater in most other regions were controlled by natural background conditions. Through the newly proposed regional groundwater quality evaluation method, groundwater quality evaluation results and groundwater resources were combined, and the proportion of abundant high quality groundwater area was highlighted in the whole area. Finally, the problem of excessive over-standard rate in the regional groundwater quality evaluation results was effectively resolved.

Abstract:[Objective] The temporal and spatial variation characteristics of vegetation phenology and its response to climate change were analyzed to provide a theoretical basis for regional desertification land control and restoration, and for reconstruction of degraded ecological environment. [Methods] NDVI data for the Mu Us sandy land from 2000 to 2019 were used to determine the temporal and spatial variation characteristics of vegetation phenology and their responses to climate change. The vegetation growth curve was reconstructed using the double logic function method. The vegetation start of season (SOS), end of season (EOS), and growing season length (GSL) were extracted using the dynamic threshold method. Phenology trend was determined by Theil-Sen median and the Mann-Kendall methods. The relationship between phenology and climate was studied by correlation analysis and F test. [Results] ① SOS was advanced by 0.7 day/year; EOS change trend was not obvious; and GSL was extended by 0.75 day/year. ② The multi-year mean value of SOS for vegetation was mainly concentrated at day of year (DOY) 90—140 d, and was gradually delayed from east to west. The multi-year mean value of EOS for vegetation was mainly concentrated at DOY 300—330 d, and was gradually advanced from south to north. The multi-year mean value of GSL for vegetation ranged from 180 to 250 d, and was gradually shortened from east to west. ③ The area of SOS in Mu Us sandy land was negatively correlated with cumulative precipitation in spring (90.81%), precipitation in March (83.85%), and precipitation in April (61.70%), and was negatively correlated with average temperature before the spring season (58.85%), average temperature in March (60.01%), and average temperature in April (51.95%). The area of EOS was positively correlated with accumulated precipitation before the autumn season (54.99%), precipitation in September (63.67%), and precipitation in October (42.34%), and was positively correlated with average temperature before the autumn season (54.95%), average temperature in September (44.70%), and average temperature in October (50.50%). [Conclusion] Over the period during 2000—2019, vegetation SOS was generally advanced, changes to vegetation EOS were not obvious, and vegetation GSL was prolonged. Cumulative precipitation before spring and precipitation in March were the main factors influencing vegetation SOS advance, and precipitation in September was the main factor influencing vegetation EOS advance.

Abstract:[Objective] The temporal and spatial differentiation of land use and land cover change of the Lijiang River basin during 2000—2020 was analyzed in order to provide a basis for spatial governance for coordinated human activities and ecological security. [Methods] Based on remote sensing information identification and GIS spatial analysis platform, expansion intensity, transition matrix and time-space statistics and spatial self-organization methods were used to study the changing laws of land use and landscape structure. [Results] ① The main landscape of the Lijiang River basin was forest land and cultivated land, accounting for more than 90% of the landscape area. During 2000—2020, the area change rate was less than 0.37%, and the expansion intensity was less than 3.59% per year, indicating that the watershed had high-quality landscape ecology resources and ecological capital to build an international tourism center. Besides, its landscape structure was stable, and water ecology was good. ② Construction land had the fastest growth and significant expansion. Its area increased by 163.41% during 2000—2020, of which the average annual expansion of Lingui New District was 37.79%. Urbanization was the main driving force for landscape type and structural changes, and the water ecosystem was well maintained. ③ The watershed landscape types were rich in diversity, the landscape distribution was balanced. The diversity and evenness index formed a high-value center in cities and towns and tourism centers, while in mountainous areas, it was a low-value continuous area. The connectivity was good, the mountainous area was the high value center and the town was the low value center. Human activities had a significant disturbance to the grassland shape and the surrounding area of the town (median area). [Conclusion] The watershed landscape index structure is affected by similar occurrence environment and differentiation factors and that has spatial agglomeration distribution characteristics. Urban expansion and tourism activities are the main drivers of the differentiation of the landscape pattern of the Lijiang River basin. Regional development is more suitable for centralized urbanization and decentralized tourism.

Abstract:[Objective] The characteristics of soil erosion at Castanea mollissima woodlands in the Dabie Mountains were studied in order to provide scientific support for the comprehensive prevention and control of soil erosion and ecological security in this area. [Methods] Data for this study came from Luotian County, Hubei Province well known as the 'No. 1 Castanea mollissima County in China’. Rainfall, runoff, sediment, and vegetation coverage of three Castanea mollissima woodlands on slopes of 10°, 15°, and 20°, and of two abandoned runoff plots were observed to study the characteristics of soil erosion at Castanea mollissima woodlands in the Dabie Mountains. [Results] ① Although the vegetation coverage on the Castanea mollissima plots was higher than on the abandoned runoff plots, the soil erosion degree was more serious than on the abandoned land under the same slope and rainfall conditions, indicating that the Castanea mollissima woodlands had obvious soil erosion under the forest. ② Soil erosion was weaker in plots with lower vegetation coverage. However, soil erosion was not necessarily the weakest when the vegetation coverage was the highest. This means that even under the same rainfall, soil, and slope conditions, the vegetation coverage cannot be the only indicator of the degree of soil erosion. The composition and structure of vegetation must be considered. ③ Soil erosion on the Castanea mollissima plots did not increase with increasing slope, and there was a peak of soil erosion at about 15°. [Conclusion] Castanea mollissima is widely distributed in the Dabie Mountains. The phenomenon of soil erosion under Castanea mollissima requires further attention from scientific research and management departments.

Abstract:[Objective] The response characteristics of vegetation NDVI to population density change were explored to reveal the migration track of vegetation NDVI and population density center of gravity in the Bohai Rim region, in order to provide a theoretical basis for vegetation monitoring and management and ecological environment protection in the region. [Methods] Based on the MOD13A3 NDVI and population density time series from 2000 to 2020, the methods of Theil-Sen Median analysis, Mann-Kendall significance test, Granger causality test, Getis-Ord G_i^* analysis, and center of gravity transfer model were used to study the spatio-temporal variation of vegetation cover and the hotspot variation of population density. [Results] ① from 2000 to 2020, NDVI in the Bohai Rim region showed an upward trend, with an upward slope of 0.022/10 a, and the area of NDVI rising was much larger than that of falling area. The rising rate of NDVI from 2000 to 2010 was significantly higher than that from 2010 to 2020. ② From 2000 to 2020, the proportion of hot spots and cold spots in the change of population density in the Bohai Rim region was 11.26% and 46.84% respectively. The change of population density was mainly in the cold spot region, which mainly extended in strips from the northeast of the Bohai Rim region to the northwest and some areas in the southeast of Shandong Province. ③ There was a one-way Granger cause of population density on NDVI around the Bohai Sea. The change of population density was the Granger cause of the change of NDVI, while the change of NDVI was not the Granger cause of the change of population density. On the whole, the growth of population density mainly had a negative effect on regional NDVI. The higher the degree of population agglomeration, the more significant the decline of NDVI. ④ There was no obvious spatial pattern in the migration direction of NDVI center of gravity of vegetation from 2000 to 2020, but it generally migrated to the northwest, and the center of gravity of population density migrated from the southeast to the northwest. [Conclusion] From 2000 to 2020, the NDVI in the Bohai Rim region shows an upward trend. The increase of population density has a negative impact on the change of NDVI. Further study needs to be conducted considering the impact of population density change and climate change on NDVI change in the Bohai Rim region.

Abstract:[Objective] The landscape ecological risk assessment and driving factors in the Ordos-Yulin area was analyzed, in order to provide a scientific basis for the management and restoration of the ecological environment and the construction of the ecological security pattern in this area. [Methods] Based on the land use data of Ordos-Yulin area in 2000, 2010 and 2020, ArcGIS 10.2 and Fragstats 4.2 software were used to construct a landscape ecological risk assessment model based on the degree of landscape disturbance and landscape vulnerability. The dynamic analysis of landscape ecological risks was carried out at spatial and temporal scale, and the driving factors of its changes were detected by using geographic detector. [Results] ① Grassland, cultivated land and unused land were the main land use types in Ordos-Yulin area, and the intensity and speed of land use was the most active from 2010 to 2020. Grassland was the main type of transfer in and out. ② From 2000 to 2010, the areas with medium ecological risk, high ecological risk and high ecological risk showed an expansion trend, while the low ecological risk and low ecological risk showed a contraction trend. From 2010 to 2020, the areas with medium ecological risk, higher ecological risk, and low ecological risk showed a contraction trend, while areas with low ecological risk and lower ecological risk showed an expansion trend; ③ The global autocorrelation analysis of Moran’s I index in 2000, 2010, 2020 was greater than 0.8, showing a significant positive correlation in spatial distribution. Most ecological risk units presented high-high and low-low distribution, and a small number of ecological risk units were high-high and low. The distribution around the low-risk unit indicated that the ecological risk in the study area was relatively stable. ④ According to the analysis of geographic detectors, the degree of human disturbance had a strong explanatory power for landscape ecological risks, followed by NDVI. Various ecological protection activities directly promoted the improvement of NDVI. [Conclusion] Landscape ecological risks in Ordos-Yulin area are mainly affected by human activities, and human activities mainly ecological protection activities, can effectively reduce ecological risks. Accordingly, ecological protection measures should be strengthened to promote ecological security patterns in Ordos-Yulin area.

Abstract:[Objective] The temporal and spatial evolution characteristics of the productive-living-ecological land use and its ecological environmental effects in the Central Plains urban agglomeration from 2000 to 2020 were analyzed in order to provide references for the optimization of the productive-living-ecological space pattern in rapidly urbanized areas and for regional ecological environmental protection. [Methods] Based on land use data of the Central Plains urban agglomeration in 2000, 2010, and 2020, the ecological environmental quality index and the landscape pattern index were used to quantitatively analyze the ecological environmental effects of the productive-living-ecological land use transition in the Central Plains urban agglomeration. [Results] ① The area of production land in the study area decreased significantly (-7 890 km²), the area of ecological land was relatively stable (changing only 0.1%), and the area of living land increased rapidly (7 638 km²). The conversion of productive-living-ecological land use from 2000 to 2010 was much lower than in 2010—2020. ② The eco-environmental quality index of the study area initially rose and then fell, showing an overall spatial pattern of “high in the west and low in the east”. Zhengzhou City had the largest decline, and Jiyuan City increased the most. LPI, LSI, COHESION, AI, SHDI were highly correlated with EV. ③ The improvement trend of the ecological environment was less than the deterioration trend. The main factors causing deterioration were the conversion of forest and grass ecological land to agricultural production land and the occupation of agricultural production land by living land. ④ The fragmentation of various landscapes increased over time, and the degree of aggregation and connection decreased over time. The shape of the landscape tended to become irregular, the diversity and uniformity have increased, and the overall ecological environmental quality deteriorated. [Conclusion] The evaluation results of the eco-environmental effects of the two evaluation indexes on the transformation of productive-living-ecological land use tended to be consistent, i.e., the eco-environmental quality of the study area has declined over time. The occupation of forest land and grassland ecological land by agricultural production land is the main factor of ecological environment deterioration.

Abstract:[Objective] The pollution status of groundwater in ion-type rare earth mining areas and its changes on the temporal and spatial scales were explored in order to provide a scientific basis for the prevention and control of regional groundwater pollution, and to guarantee a healthy life for residents. [Methods] Ten sets of groundwater samples were collected from an ion-adsorbed rare earth mine in Northern Guangdong Province during both the wet season and the dry season. Based on the detection of six conventional indicators and seven heavy metal indicators in water samples, the current groundwater pollution status was analyzed and evaluated by using multivariate statistical methods and the revised Nemerow comprehensive pollution index method. [Results] Groundwater exceeding standard components included sulfate (10%), nitrate nitrogen (30%), ammonia nitrogen (35%), fluoride (40%), sulfide (40%), Mn (55.5%), Pb (20%), and Cd (10%). The degree of pollution due to excessive ammonia nitrogen and Mn were significantly more serious. Only the concentrations of sulfide and fluoride in the over-standard components had obvious period characteristics, and they were both characterized by being greater during the wet season than during the dry season. Groundwater pollution was very uneven, and the overall pollution level was very severe. Groundwater quality in the wet season was worse than in the dry season, and pollution was concentrated to a greater extent at sample points DXS₀₄, DXS₀₆, and DXS₀₇. [Conclusion] All pollution indicators had a migration and conversion relationship with chemicals used in rare earth mines. Groundwater affected by rare earth mines in the study area was no longer suitable as a source of drinking water.

Abstract:[Objective] The temporal and spatial variation of vegetation coverage in the Kubuqi Desert during 1989—2019 was explored in order to provide the necessary theoretical basis and support for ecological restoration of the local area. [Methods] Landsat images acquired every five years from 1989 to 2019 was used, combined with the normalized difference vegetation index (NDVI) model, ENVI 5.3, and ArcGIS 10.2 to analyze the fractional vegetation coverage (FVC) variation of the Kubuqi Desert during 1989—2019. [Results] ① In terms of temporal variation, the average fractional vegetation coverage of the Kubuqi Desert increased from 0.104 to 0.243 during 1989—2019. In terms of spatial distribution, fractional vegetation coverage increased from west to east and north in the Kubuqi Desert. ② The fractional vegetation coverage of the Kubuqi Desert declined during 1999—2004 and 2009—2014. The average fractional vegetation coverage for those two periods decreased by 0.053 and 0.054, respectively, and the degraded areas were 3 870.22 km² and 6 093.59 km², respectively. [Conclusion] On the whole, the vegetation coverage of the Kubuqi Desert increased during 1989—2019. In the future, local ecological restoration efforts should focus on the low vegetation coverage areas.

Abstract:[Objective] The change of land use and ecological service value in Shaoshan City, Hunan Province was analyzed to discusse the impacts of land use change on the surrounding land ecological service value, in order to provide a scientific reference for the related research of land use change and ecological service value, and to determine an ecological service value evaluation system. [Methods] Using remote sensing images in 1985 and 2020, land use data were extracted by remote sensing interpretation. Based on the basic definition of ecosystem service, land use change and the relationship between land ecosystem service value were comprehensively considered. A related concept was put forward and a remote correlation model was built. The surrounding land ecosystem service value following land use change was discussed. [Results] ① Land use conversion mainly occurred between forest land, cropland, and grassland, and the land dynamic attitude of forest land was the largest (about 3%). ② The value of ecosystem services in Shaoshan City increased year by year from 1.266 billion yuan in 1985 to 2.201 billion yuan in 2020, and the contribution rate of forest land to the ecosystem services value was 70%. ③ During the study period, the remote correlation added value of land use change to the surrounding land ecosystem service value was 467 million yuan. The impact of land use change on the value of surrounding land ecosystem services decreased with increasing distance, until a critical distance was reached, and the critical distance varied with different land types. When land use type was converted to water body, the critical distance was the largest, about 100 patches (land type conversion area). [Conclusion] In the future, the impact of land use change on surrounding land should be comprehensively considered in land planning so as to formulate reasonable land use policy, optimize land use structure, and realize the coordinated development of economy and environment in Shaoshan City.

Abstract:[Objective] The influence of topographical factors on land use pattern and spatial structure characteristics was explored in order to provide a scientific reference basis for the planning and decision-making of land development and utilization in Dashanbao area. [Methods] Terrain gradient analysis method and fractal theory were used to explore the terrain gradient effect and spatial structure characteristics of land use. [Results] ① There were significant differences in the spatial distribution patterns of various land use types in Dashanbao area at different altitudes, slopes and topographic index. ② The topographic index range of the dominant distribution of cultivated land, construction land and water area were all 0.26～0.53, forest land was 0.53～1.21, grassland was 0.44～0.60, unused land was 0.26～0.53 and 0.71～1.21. ③ The comprehensive land use intensity index and the land use diversity index gradually decreased from 234.75 and 0.82 to 218.49 and 0.63 respectively with the increase of altitude and slope, and then increased to 221.02 and 0.67 respectively, and the both decreased first and then increased with the increase of altitude and slope. ④ The fractal characteristics of the distribution of each category were obvious, and the fractal dimension was between 1.191 1～1.6 688. The stability of each category was in the order of forest land (0.308 9)＞ construction land (0.282 8)＞ cultivated land (0.264 1)＞ unused land (0.199 7) ＞ water (0.168 8)＞ grass (0.135 1). [Conclusion] The land use pattern and spatial structure characteristics of Dashanbao area are significantly affected by topographic factors, and the characteristics of topographic gradient are obvious.

Abstract:[Objective] The temporal and spatial variation characteristics of ecosystem service value in Fenhe River basin from 1980 to 2020 were analyzed to provide theoretical reference for scientific regulation and management of ecological environment in the basin. [Methods] Based on interpretation data of landsat-MSS/TM/ETM remote sensing image from 1980 to 2020, the land use change characteristics of Fenhe River basin were studied, and the ecosystem service value was estimated. [Results] From 1980 to 2020, the cropland, forest and grassland had been in the leading position in the land use of Fenhe River basin. The overall change of land use was mainly from cropland to construction land, and the changing rate of land use from 2000 to 2020 was significantly higher than that from 1980 to 2000. The annual value of total ecosystem services in the Fenhe River basin decreased from 1980 to 2020.The spatial distribution of ecosystem service value (ESV) was higher in the upstream and lower in the downstream. From the perspective of different function values, the regulation and support services decreased the most. The land use degree and ESVI bivariate LISA aggregation map showed a significantly spatially negative autocorrelation pattern, which was mainly dominated by low land use degree and high ESVI aggregation distribution in the upper reaches of Fenhe River. [Conclusion] Land use/cover change of Fenhe River basin had a great impact on ESV during 1980—2020. Measures such as improving the level of land intensive use should be used to improve land use structure developing towards high ESV.

Abstract:[Objective] Changes in productive-living-ecological land and its spatial conflicts in Urumqi City, Xinjiang Wei Autonomous Region, were studied in order to provide references for the optimal allocation of land resources in this region. [Methods] A spatial conflict measurement model at the grid scale was constructed for Urumqi City from the three factors of external pressure, vulnerability, and stability. The spatiotemporal characteristics of spatial conflicts in this region from 2000 to 2018 were then quantitatively evaluated. [Results] ① From 2000 to 2018, the northern part of Urumqi City was the main growth direction for urban living land, and the spatial pattern of agricultural production land showed a fragmentation trend. Ecological land was the main component of productive-living-ecological land in Urumqi City. Therefore, the occupation of new core ecological land by human activities should be avoided. ② The conflict levels of productive-living-ecological space in each period followed the order of stable and controllable ＞ minor conflict ＞ moderate conflict ＞ heavy conflict. ③ The spatial unit of severe conflict had the largest increase, indicating that the scope of uncontrolled severe conflict in the study area was expanding, and should be the key area of spatial conflict regulation in Urumqi City. ④ There were some differences in spatial conflicts among different spatial types, and conflict intensity followed the order of productive space ＞ living space ＞ ecological space. [Conclusion] Changes in productive-living-ecological land in Urumqi City was strongly influenced by regional economic and social development. In the future, the phenomenon of conflict level gradually increasing due to the rapid expansion of living space should be gradually changed. The dynamic monitoring of urban living land should be given more attention, and the core ecological land should be protected in order to achieve more coordinated land use.

Abstract:[Objective] The dynamic change of leaf area index (LAI) and its response to climatic factors in Ulanqab City were studied in order to provide a scientific basis for rational resource allocation and ecological conservation. [Methods] Based on the Copernicus Climate Change Service PROBA-V LAI data and meteorological data from July to August during the period of 2000—2019, the spatiotemporal variation of LAI and its relationship with temperature, precipitation, and soil moisture in Ulanqab City were explored using linear trend analysis, coefficient of variation analysis and correlation analysis. [Results] ① Average LAI showed a fluctuating upward trend at a growth rate of 0.01 per year in Ulanqab City during the study period. Significant differences were found in the spatial distribution of LAI, which was characterized by high LAI in the southeast and low LAI in the northwest. ② Although 88.3% of the study area showed an increasing trend for LAI, the change of LAI was relatively unstable during the study period. A significant increasing trend was found in most of Xinghe County, the east of Fengzhen City, the west of Liangcheng County, the southwest of Siziwang Banner, and the central and northern parts of Chahar Right Middle Banner, while a slowly increasing or decreasing trend was found in most areas of Houshan Mountain in the north of Yinshan Mountain. ③ LAI showed a significant negative correlation with temperature, and a highly significant positive correlation with precipitation and soil moisture. The correlation of LAI with soil moisture was higher than that of precipitation and temperature. ④ No significant difference was found in the spatial distribution of correlation coefficients between LAI and temperature, precipitation, and soil moisture. Most areas had negative correlations between LAI and temperature, with 45.4% of the study area showing significant negative correlations. LAI had significant positive correlations with precipitation and soil moisture, and the area of significant correlation between LAI and soil moisture was larger than that of precipitation. [Conclusion] During 2000—2019, the LAI of vegetation in Ulanqab City showed an increasing trend and obvious spatial heterogeneity. Soil moisture was the decisive factor affecting vegetation growth.

Abstract:[Objective] In order to provide scientific support for specifying soil erosion control values of production and construction projects, this study discussed whether currently used methods of defining soil erosion control were capable of satisfying multiple needs, and attempted to implement a method for defining soil erosion control values that will maintain multiple ecosystem service functions. [Methods] Taking Beijing City as an example, soil loss tolerance and background soil erosion moduli were selected, which can be easily obtained, as the references for defining the soil erosion control values, to analyze their advantages and disadvantages on maintaining regional ecosystem service functions in different areas. A method was carried out for defining soil erosion control values of production and construction projects for maintaining multiple ecosystem service functions. [Results] Soil erosion control values obtained from soil loss tolerances could keep provisioning and cultural services in mountain areas, but could not in plain and some environmentally sensitive areas. The situation was reversed when soil erosion control values obtained from background soil erosion moduli. Defining the soil erosion control values of production and construction projects by combining the mentioned two methods could keep provisioning and cultural services both in mountain and plain areas. [Conclusion] The method for defining soil erosion control values of production and construction projects, by which multiple ecosystem service functions are maintained, could overcome the disadvantages of the values defined only by soil loss tolerance. The method provides a new pathway for setting prevention and control goals for soil and water conservation.

Abstract:[Objective] The effects of application researches of humic acid in soil improvement and pollution remediation were summarized in order to provide a significant reference for application research and product development of humic acid. [Methods] Based on the long-term researches on characteristics and practical application of humic acid resources, and referring to a large number of academic literatures on humic acid research, the principle, technology and application of humic acid in soil improvement and remediation of soil pollution were comprehensively analyzed. [Results] Humic acid can improve soil aggregate structure, improve fertilizer utilization efficiency, maintain soil acid-alkali balance, and promote soil biological activity. Humic acid plays an important role in mitigating the degradation of soil, improving saline-alkali land, reclaiming abandoned land, and remediating heavy metal and organic pollution of soil. At present, there are some problems regarding the application researches in soil improvement and pollution remediation. ① The sources and classification of humic acid are unclear, and basic researches are insufficient. ② Research and development of new humic acid materials and technologies are slow, and the overall technology of the industry needs to be improved. ③ The construction of technical specifications and standards in humic acid does not match the application and development of humic acid, thereby limiting the speed of promotion. [Conclusion] Future research emphasis should be placed on the following areas: ① Basic research on classification, component separation, and interaction between coal-based and biological humic acid resources. ② Applied basic research on humic acid in soil improvement and pollution remediation. ③ Researches on detection methods and formulation of product quality standards of humic acid. ④ Applied researches and development on new humic acid products and construction of demonstration parks.

Abstract:[Objective] The developing status and issues of ecological industry in mountainous areas of Southern Ningxia Hui Autonomous Region were analyzed, and the developing strategies were proposed in order to provide references for development of ecological industry, and to support regional ecological protection and high-quality development. [Methods] Through the surveys given to local famers and corporate employees, discussions with many experts and government administrative officers, as well as access to relevant literatures, the status of ecological industry was summarized, existing issues were analyzed, and developing strategies were also discussed. [Results] In recent years, with the development of ecological restoration, five major ecological industries have been established, including dryland grain production, livestock, fruit, vegetables, and Chinese herbal medicine. These ecological industries have shown strong local characteristics and a trend for rapid development. Livestock and vegetable production showed higher economic benefits and have the potential for greatly improving farmers’ income. These two sectors have good prospects and opportunities for future development and promotion. However, there are still some issues need to be solved, such as improving coordination between ecological restoration and the ecological industry, reducing mismatches between ecological resources and the layouts of ecological industries, failures in implementing key technologies, and insufficient scientific and technological support. [Conclusion] In the future, this region should strengthen the integrated design of ecological restoration and ecological industry, develop new ecological industries, explore the utilization of ecological resources, strengthen research on key technologies, and strengthen support for scientific researches and development of a technically capable workforce.

Abstract:[Objective] In order to provide references for urban soil and water conservation and the concerned researches in China, the concept, hazard, causes, characteristics and countermeasures of urban soil and water loss were summarized. The existing problems and future research direction of urban soil and water conservation were analyzed. [Methods] Based on many years of research experiences and some concerned literatures, the research achievements of urban soil and water loss and soil and water conservation domestic and abroad were comprehensively analyzed. [Results] ① The concept of urban soil and water loss contains two kinds of driving forces: natural and artificial, two main bodies of soil and water loss, two spatial distribution include urban and surrounding areas, and surface and underground areas. ② The hazards of urban soil and water loss mainly include pipeline deposition, wind sand and dust, water source pollution, resource decline, environmental damage, and so on. ③ The prevention and control measures of urban soil and water loss mainly include the aspects of law, mechanism, propaganda, supervision, concurrent treatment and scientific research. [Conclusion] People’s understanding of urban soil and water loss is still insufficient, and the theory, technology and legal system of urban soil and water conservation need to be improved. Urban water and soil loss and water and soil conservation should be carried out further in terms of theoretical research, application optimization and experience extension.

Abstract:[Objective] The present situation, problems, and development strategy for comprehensive control in the desert regions of China in the context of international and national conditions, science and technology, and climate change in a new era were studied in order to provide references for the formulation of ecological protection, rational development, and utilization of desert resources and related scientific research. [Methods] Relationships between the distribution of China’s desert regions and national conditions, climate change, and carbon neutrality were analyzed. Based on the latest research progress in the fields of desert control, ecological restoration, and desert resource development and utilization in China in a new era, a development strategy for China’s desert regions was proposed that considered problems included ecological environment destruction and existing comprehensive control of the desert regions of China. [Results] The development strategy, basic principles, and design concept for the desert regions of China in a new era were expounded. A comprehensive development strategy for the desert regions of China in a new era and its implementation path were proposed. Additionally, objectives and vision planning were put forward. The relationships between the strategy and the national overall development strategy and global trends were discussed. [Conclusion] Under the conditions encountered in this new era, it is necessary to reposition the desert regions, so as to fully explore the comprehensive potential of the desert regions under the principle of ecological priority. Doing so will assist the great rejuvenation of the Chinese nation, and contribute Chinese wisdom and strength to the construction of a community with a shared future for mankind.