Abstract:[Objective] The relation between root system distribution and soil physical and chemical properties of grasslands was analyzed to provide a theoretical basis for the management of grassland desertification in Western Tibet.[Methods] Grasslands with different degrees of desertification were taken as the research object. The sampling was undertaken according to the S-shaped method, and the physical and chemical properties of the 0-15 cm soil layer were analyzed.[Results] The root content decreased with the aggravation of the desertification degree. As desertification progressed, both the pH value and available potassium first increased and then decreased, the volume weight showed an upward trend, and the soil water content, organic matter, total nitrogen, alkali-hydrolyzed nitrogen, and available phosphorus showed a downward trend. The root content of the grassland was significantly negatively correlated with pH value and volume weight (p<0.01), and the correlation coefficients were -0.806 and -0.735. The root content of the grassland was significantly positively correlated with soil water content, organic matter, total nitrogen, alkaline hydrolysis nitrogen, and available phosphorus. The correlation coefficients were 0.771, 0.658, 0.590, 0.686, and 0.382.[Conclusion] Root distribution is correlated with many soil and chemical properties and restricted by soil physical-chemical proprieties.

Abstract:[Objective] The regional characteristics of rainfall erodibility in karst ecologically fragile areas were studied in order to provide scientific reference for soil erosion prevention and eco-environment protection.[Methods] Long-term (1960-2017) daily precipitation data from 33 meteorological stations were assembled to analyze the spatial and temporal variations of rainfall erosivity in different river systems of Guizhou Province, and the spatial interpolation, linear trend, gravity model, mutation test, and cluster analysis methods were used.[Results] The rainfall erosivity of the eight river systems mainly showed a fluctuating downward trend, which was consistent with the regional variation trend based on the cluster division, but an abrupt change was not obvious. The spatial variability of rainfall erosion was great. The spatial distribution of rainfall erosivity in the Yangtze River basin decreased from southeast to northwest, while that in the Pearl River basin increased from east to west. Heavy rain was closely related to rainfall erosivity because the migration path of the gravity center was similar to that of rainfall erosivity, and the gravity centers were mainly concentrated in Guiyang City and its surrounding areas. Most of the river systems showed a significant correlation (p<0.05) between rainfall erosivity and longitude, latitude, altitude, and slope, but the correlation with aspect was not obvious.[Conclusion] The spatiotemporal variability of rainfall erodibility in various water systems in Guizhou Province is strong, and the regional characteristics are obvious. Soil erosion control should be carried out in karst ecologically fragile areas according to regional characteristics.

Abstract:[Objective] The root distribution parameters of grass-shrub vegetation (Cynodon dactylon, Vetiveria zizanioides, and Amorpha fruticosa) on soil reinforcement on the banks of the canal of Ezhou airport were analyzed quantitatively to provide a theoretical basis for better evaluation of the effectiveness of vegetation root soil.[Methods] The root-drill sampling method was used to explore the changes in grass-shrub root distribution parameters at different depths. Indoor direct shear tests and outdoor tensiometer tests were carried out to study the effect of root distribution parameters on shear strength indices and matrix suction.[Results] ① The root distribution of grass-shrub vegetation generally decreased with increasing soil depth. The root distribution parameters of shrubs (A. fruticosa) and herbs (C. dactylon and V. zizanioides) were 2.13-2.90 times in the depth range of 0-40 cm. ② The cohesion of the shrub root-soil composite was significantly higher than that of the herbs, and the cohesion satisfied a polynomial function relationship with root length density (RLD) and root surface area density (RSAD). ③ RLD and RSAD had significant differences in cohesion and matrix suction (p<0.05). ④ There was an optimal root density for the RLD and RSAD of shrubs (A. pseudoacacia) to enhance the suction of the soil matrix.[Conclusion] The root systems of C. dactylon, V. zizanioides, and A. fruticosa can play a significant role in soil fixing. Owing to their root distribution, soil fixing depth, soil fixing methods, the three plants have different soil-fixing functions. The three plants can be combined for planting, which is not only beneficial to the stability of riverbank slopes, but also improves the soil erosion resistance.

Abstract:[Objective] To provide technical support for desertification control, the effects of grass planting methods on vegetation restoration of moving sand dunes in alpine grasslands were studied.[Methods] On a moving sand dune of Maqu County, Gansu Province, experiments involving different seeding modes, different grass species, and different grass planting modes were conducted to analyze the effects of different grass planting methods on vegetation restoration.[Results] Broadcast seeding and drill seeding had no significant effect on vegetation restoration. Overall, grass species had little effect on vegetation restoration, and it was only necessary for planting Elymus nutans in the vegetation restoration of moving dunes. The planting mode had a significant effect on vegetation restoration. In the second year of grass planting, the height, density, coverage, above-ground biomass fresh weight, and dry weight of grass were significantly increased in paving cow and sheep dung mode compared with no paving cow and sheep dung mode. In the same modes of paving cow and sheep dung, the height and coverage of grass were significantly higher in "cow and sheep dung + no sand barrier grass" mode with a thickness of cow and sheep dung of approximately 2 cm than in "cow and sheep dung + sand barrier grass" mode with a thickness of cow and sheep dung of approximately 1 cm. The grass growth status was positively correlated with soil nutrient and water holding capacity.[Conclusion] "Cow and sheep dung + no sand barrier" grass planting mode was the optimal mode of vegetation restoration of moving dunes in the study area. If the thickness of the cow and sheep dung was approximately 2 cm, it was no longer necessary to set other sand barriers for sand fixation.

Abstract:[Objective] The response characteristics of carbon and nitrogen in rhizosphere soil of semiarid grasslands and soil microbial biomass to different years of grazing exclusion were studied to provide basic information for the study of the material cycle of semi-arid grassland ecosystems and the determination of ecosystem nutrient limits, and to determine reasonable grazing exclusion periods.[Methods] Taking the typical semi-arid grassland of Yunwushan National Nature Reserve in Guyuan City, Ningxia Hui Autonomous Region, as the research object, the ecological stoichiometric method was used to compare and analyze the variation process and rule of rhizosphere soil organic carbon, total nitrogen, nitrate nitrogen, ammonium nitrogen, and soil microbial biomass carbon and nitrogen content, as well as the stoichiometric characteristics of the grazing land and the sampled land enclosed for 10, 25, and 35 years.[Results] Enclosure treatment significantly increased the soil carbon and nitrogen content. The maximum values appeared in the plot enclosed for 25 years, after which the values declined. The soil organic carbon contents of the plots enclosed for 10, 25, and 35 years were 1.37, 1.83 times and 1.38 times of that of the grazing plot, and the total nitrogen contents were 1.34, 1.52, and 1.24 times of that of the grazing land, respectively. However, soil C:N remained stable with the increase in enclosure years. It was significantly correlated with soil organic carbon content but had no evident correlation with soil total nitrogen. Compared with that of the grazing plot, the ammonium nitrogen content of enclosed plots did not change significantly with the enclosure years, but the nitrate nitrogen content and the nitrate:ammonium nitrogen ratio generally decreased, with the lowest values at 25-year grazing exclusion. Enclosure significantly increased the soil microbial biomass carbon and nitrogen content. The soil microbial biomass carbon contents of the sample plots enclosed for 10, 25, and 35-years increased by 20.5%, 45.7%, and 15.1% compared with grazing land, while the microbial biomass nitrogen contents increased 24.7%, 60.5%, and 40.9%, respectively. The microbial biomass C:N value decreased with the extension of the enclosure period. The percentage of microbial biomass carbon in soil organic carbon did not respond to the enclosure period. Compared with grazing land, 10-year and 25-year grazing exclusion had no significant difference in the percentage of microbial biomass nitrogen in total soil nitrogen and the stoichiometric imbalance (i.e., the ratio of soil C:N to microbial biomass C:N), but the value significantly increased in 35-year grazing exclusion.[Conclusion] Enclosure measures can significantly improve soil carbon and nitrogen nutrients in semi-arid degraded grasslands, promote soil microbial activities, and facilitate the restoration of degraded grassland. However, a too long enclosure treatment may have a negative effect. Twenty-five years of enclosure is a reasonable enclosure period in long-term enclosure measures of degraded grasslands.

Abstract:[Objective] The changes in soil physical and chemical properties under different alpine vegetation in the Eastern Qilian Mountains were explored to provide a theoretical basis for the rational utilization of regional water resources.[Methods] The basic soil properties, soil water holding capacity, and soil permeability of different alpine vegetation types were studied.[Results] ① The soil bulk density in the Eastern section of the Qilian Mountains increased with the increase in soil depth, while the soil water content decreased with the increase in soil depth. ② The total soil porosity in the Eastern Qilian Mountains decreased with the increase in soil depth, and the capillary pores and noncapillary pores had no obvious vertical variation. ③ The maximum soil water holding capacity gradually increased as the depth of the soil layer increased. The soil capillary water holding capacity showed a trend of first decreasing and then increasing. The soil noncapillary water holding capacity had a slightly different pattern. ④ The initial soil infiltration rate (0.58 to 2.81 mm/min) in the eastern section of the Qilian Mountains was higher than the average permeability (0.05 to 1.26 mm/min) and steady infiltration rate (0.04 to 1.31 mm/min). The initial soil infiltration performance of six alpine vegetations was alpine meadow > Salix oritrepha > Salix sclerophylla > Spiraea salicifolia > Rhododendron thymifolium > Potentilla fruticosa > Rhododendron capitatum. The average permeability was S. salicifolia > P. fruticosa > R. thymifolium > S. oritrepha > S. sclerophylla > Alpine meadow > R. capitatum. The steady infiltration rate was S. salicifolia > P. fruticosa > R. thymifolium > S. oritrepha > S. sclerophylla > R. capitatum > alpine meadow.[Conclusion] The different types of alpine plant in the study area had different effects on the physical and chemical characteristics of the soil in the area. There was a relationship and interaction between the physical and chemical characteristics of the soil and plants, and the two were interdependent.

Abstract:[Objective] The diversity of belowground bud banks and their underlying environmental determinants were studied in order to provide important theoretical value for protecting and restoring biodiversity.[Methods] Three habitats such as marsh (MA), marsh meadow (MM), and meadow (ME) in the Zoige Plateau wetland were selected as the study object, and the experimental data were processed by single-factor analysis of variance, correlation analysis, and path analysis.[Results] ① The total density of the belowground bud bank in MA was the largest, followed by those of MM and ME. Among the habitats, significant differences were recorded. Bud banks in MA were dominated by horizontal apical rhizome buds, while the bud banks in MM and ME were dominated by axillary rhizome buds and shoot buds, respectively. ② The bud length of MA was much larger than that in MM and ME, and the differences between these habitats were significant. The bud diameters of MA and MM were much larger than that in ME, while no significant difference was recorded between MA and MM. The bud length/diameter in MA was significantly larger than those in MM and ME, while there was no significant difference recorded between MM and ME. ③ The total nitrogen content of belowground bud (TNB) in MA was much larger than that in MM and ME, and a significant difference between habitats was found. However, no significant differences were recorded between the habitats for both total phosphorus content of bud (TPB) and the TNB/TPB ratio.[Conclusion] Soil moisture, available nitrogen, and total phosphorus were the main factors controlling density, morphology (length and diameter), biomass, and ecological stoichiometry of belowground buds on the Zoige Plateau.

Abstract:[Objective] The law of sediment yield in a karst trough valley was studied to provide a theoretical basis for the prevention and control of soil and water loss on the slope of the trough area.[Methods] Based on the runoff plots of Zhongliang Mountain at Beibei District of Chongqing City, the effects of land use types (cultivated land, woodland, orchard, and bamboo forest land), rainfall grade, and rainfall characteristics on runoff and sediment yield on slopes were investigated.[Results] ① The total runoff of the four runoff plots was as follows:cultivated land (35.35 mm), followed by orchard land (31.51 mm), bamboo forest land (23.47 mm), and forest (19.57 mm). The runoff coefficient of them (3.12%~0.5.70%) was much lower than that of the nonkarst area (approximately 20%). The slope sediment yield of the four land uses decreased orderly, and that of the cultivated land was the largest (3.37 kg), followed by orchards (2.60 kg), forest (1.60 kg), and bamboo forest (1.43 kg). ② Although rainstorm accounted for 1.53% of the total rainfall, the runoff and sediment yield accounted for 42.28% and 33.42%, respectively. Moderate rain accounted for 16.61% of the total annual runoff, and sediment yield accounted for 20.47% of the total annual sediment yield. However, because of the frequent rainfall of moderate rain, the sediment loss caused by it can not be ignored. ③ Rainfall had the greatest impact on the runoff on slopes under different land uses. Moreover, I₃₀ had the greatest impact on the sediment yield of cultivated land and orchards, and rainfall had the greatest impact on the sediment yield of forest land and orchards.[Conclusion] Under the same rainfall conditions, the runoff and sediment yield of cultivated land are the largest, followed by those of orchards. Under certain slope conditions, different levels of rainfall are the main factors affecting runoff and sediment yield. Therefore, when arranging agricultural activities, it is necessary to avoid high-intensity rainfall to reduce the occurrence of serious erosion events.

Abstract:[Objective] The distribution of soil physical and chemical properties and herbaceous vegetation among desert shrub microhabitats and their responses to precipitation change were studied to provide a basis for artificial afforestation and desertification control under future climate change in arid desertified regions.[Methods] The afforested shrubs, including Caragana korshinskii and Artemisia ordosica, were selected as research objects. The microhabitats inside and outside shrub canopies were set as sampling sites. At each sampling site, soil water content, bulk density, pH value, electrical conductivity, total carbon, total nitrogen, and soil particle size were measured, and the distribution of herbaceous vegetation was investigated, along with the climatic gradient, in the Yuyang, Yanchi, and Shapotou areas.[Results] ① In Yuyang area, soil coarse sand content and herbaceous abundance significantly increased, while the soil bulk density and soil pH value decreased in the C. korshinskii shrub microhabitats relative to the open space. Soil clay content, total carbon, and total nitrogen significantly increased, while herbaceous abundance declined in the A. ordosica shrub microhabitats relative to the open space. In Yanchi area, soil total carbon, total nitrogen, and herbaceous plant height increased, while soil fine sand content, soil bulk density, and herbaceous species richness decreased in the C. korshinskii shrub microhabitats relative to the open space. Soil clay content and herbaceous species richness decreased in the A. ordosica shrub microhabitats relative to the open space. In Shapotou area, soil electrical conductivity decreased in the C. korshinskii shrub microhabitats, while there were no herbaceous plants observed in A. ordosica shrub microhabitats relative to the open space. ② Along with the increase in the precipitation amount from the Shapotou area toward the Yuyang area, soil fine sand content, soil bulk density, and soil electrical conductivity decreased, while soil nutrients and herbaceous species richness, abundance, and height increased.[Conclusion] The afforestation strategies in desertified regions depended on shrub species and the precipitation distribution. C. korshinskii and A. ordosica shrubs afforested in Yuyang, C. korshinskii shrubs afforested in Yanchi, and C. korshinskii shrubs afforested in Shapotou could be an option for the recovery of soil-vegetation systems in desertified regions.

Abstract:[Objective] The spatial variations in surface soil erosion resistance in the low elevation areas of the Helan Mountains in Ningxia Hui Autonomous Region were analyzed to provide useful references to environmental protection and ecosystem management and construction in this ecologically vulnerable area.[Methods] A field survey and laboratory measurements of the surface soil samples collected across the low elevation area of the Helan Mountains were conducted. The key factors determining surface soil erodibility were identified and a comprehensive evaluation model of soil erosion resistance was constructed to analyze the soil erosion resistance in the areas 1 300-1 800 m in elevation.[Results] ① The soil moisture content, total porosity, clay, silt content, and fractal dimension had significantly positive correlations with elevation and the bulk density and sand content had significantly negative correlations with elevation. These seven soil factors showed variability at weak or moderate levels. Therefore, they can be selected as the influencing factors of soil erodibility. ② Significant correlations between the influencing factors of soil porosity and soil particle size were found, suggesting information redundancy. ③ The comprehensive evaluation model of soil erosion resistance suggested that soil erosion resistance weakened as the elevation decreased from 1800 to 1300 m, showing a significantly positive correlation with elevation.[Conclusion] The soil properties and soil erosion resistances were significantly related to elevation in the low elevation area of the Helan Mountains. Special protection measures and soil remediation programs should be formulated to improve the soil structure and quality, strengthen soil erosion resistance, and enhance the functioning of soil and water conservation.

Abstract:[Objective] The variation in soil respiration and its components in a vineyard in an arid area in Northwest China were analyzed and the relationship between soil temperature, soil water content, and soil respiration was studied in order to provide some reference for the estimation of soil carbon emission and the development of featured agriculture in arid areas of Northwest China.[Methods] Soil respiration and environmental parameters of a vineyard at South Lake oasis of Dunhuang City, Gansu Province were observed using an LI-8 100 A soil respiration measurement system and automatic meteorological station from June to December 2019, and soil respiration components were distinguished by root exclusion methods.[Results] ① During the observation period, the soil respiration rate in the vineyard reached its maximum on July 3. The soil respiration rate fluctuated significantly from June to September during the growing season, while it decreased gradually from October to December during the non-growing season. Heterotrophic respiration was the main component in this area, and the average contribution rate of heterotrophic respiration was approximately 65%. ② On an hourly scale, the relationship of hysteresis loops between soil respiration, heterotrophic respiration, and soil temperature was obvious because of the time lag effect. On a daily scale, soil respiration and heterotrophic respiration increased exponentially with the increase in soil temperature during the non-growing season (from October to December). However, irrigation and heavy rainfall could cause fluctuations in soil water content, interfering with the above exponential responses during the growing season (from June to September). ③ During the growing season (from June to September), soil respiration and its components had a quadratic function relationship. The optimal soil water content was approximately in the range of 8.1% to 9.9%. However, there was an exponential relationship from October to December during the non-growing season. The difference was mainly caused by the decrease in soil water content and soil temperature during the non-growing season. The vine branches were buried underground, which caused the heterotrophic and autotrophic respiration to decrease rapidly to a low value and then remain stable.[Conclusion] Soil respiration was regulated by soil temperature and soil water content. The two-factor model could explain the variation in soil respiration well during the non-growing season, but it only explained 32% of the variation during the growing season. Therefore, the multifactor model of soil respiration during the growing season should be further established to better simulate the variation during the growing season.

Abstract:[Objective] The influence of replacing topsoil treatment on vegetation restoration of open-pit coal dumps in alpine mining area was investigated to evaluate the vegetation restoration effect of replacing topsoil treatment in open-pit coal mine dumps and to provide a technical basis for ecological protection and restoration in an mining area.[Methods] The vegetation community characteristics and soil physicochemical properties of five topsoil replaced and three topsoil unreplaced treatments in mining areas in the Muli coalfield of Qinghai Province were investigated and analyzed.[Results] Vegetation and seedling coverage significantly increased (p<0.05) as the planting period increased, and the available phosphorus, total potassium, available potassium, and organic matter content in the soil showed an increasing trend, but it was not significant. There was no significant difference between replacing and not replacing topsoil treatments in vegetation characteristics and soil physical and chemical properties. The results of nonmetric multidimensional scaling analysis showed that the soil nutrients, including total nitrogen, available nitrogen, available potassium, and organic matter, were the main factors affecting the vegetation growth.[Conclusion] The key measure of vegetation restoration in open-pit coal mine dumps in alpine grasslands is not the replacement of topsoil treatment but the addition of organic and chemical fertilizers.

Abstract:[Objective] The response characteristics of surface temperature in superlarge cities to different land use types were studied to provide a scientific reference for urban construction, planning, and design.[Methods] Taking Shanghai City as an example, this study used six phases of Landsat series multispectral and thermal infrared image data in the summer and winter of 2007, 2013, and 2017 to interpret land use types and retrieve land surface temperature. The characteristics of the influence of land use types inside and outside Waihuan Road in Shanghai City on land surface temperature in summer and winter based on a 900 m×900 m grid were analyzed.[Results] The surface temperature of Shanghai City in summer was characterized by the average temperature inside Waihuan Road being higher than that outside Waihuan Road with a temperature difference of 4.86℃; In winter, the surface temperature of Shanghai City was characterized by the average temperature inside Waihuan Road being lower than that outside Waihuan Road with a temperature difference of 0.17℃. In the summer, every 10% increase in the proportion of nonpermeable land surface outside Waihuan Road increased the temperature by 1.22℃, and the temperature inside Waihuan Road can increase by 0.97℃. The green space and water area were negatively correlated with the surface temperature. Every 10% increase in the percentage of green land can reduce the temperature by 1.01℃ outside Waihuan Road, and every 10% increase in the proportion of woodland can reduce the temperature by 1.06℃ inside Waihuan Road. For every 10% increase in the water area, the average temperature drops by 0.85℃.[Conclusion] In the summer, the cooling effect of green space is greater than that of water area inside Waihuan Road and smaller than that of water outside Waihuan Road. The cooling effect of water area is uniform and stable in different seasons and in different districts. The proportion of water area and green land required to form the cold island in Shanghai City is decreasing yearly.

Abstract:[Objective] The slope protection effect of plants, the mechanical properties of the root system of vetiver and the factors influencing the strength characteristics of the root-soil complex were studied to provide a reference basis for plant slope protection engineering design.[Methods] First, an outdoor model box was used to simulate the filling of red clay on the slope for vetiver planting conditions, and the mechanical properties of vetiver and the factors influencing the strength characteristics of the root-soil complex were studied through indoor tests, such as a root pull test and undisturbed root-soil composite direct shear test. Through fitting analysis and Spearman correlation analysis of the test results, the relationship between root diameter and tensile properties of vetiver and the effects of different indices on the shear strength of the root-soil complex were obtained.[Results] The average stretching resistance of the vetiver root system was 19.05 N, and the average tensile strength was 20.12 MPa. The stretching resistance and tensile strength of the root system of vetiver had a significant power function relationship with root diameter. Root weight density(RWD)decreased with increasing soil depth. The results of Spearman correlation analysis showed that the RWD and cohesive force c of the root-soil complex had a positive and strong correlation (R=0.882).[Conclusion] As the diameter of the root system of vetiver increases, its tensile strength increases and its tensile strength decreases. The increase in RWD can significantly increase the cohesive force c of the vetiver-red-clay root-soil complex, but the effect of increasing the friction angle φ is not obvious.

Abstract:[Objective] The heavy metal pollution of Coix seed and soil in its producing area were studied to provide a scientific basis for the sustainable development of the Guizhou Coix seed industry and the prevention and control of heavy metals in the soil of its origin.[Methods] The Coix seed and the soil of its producing area were used as the test samples. The soil pH value, organic matter, cation exchange capacity, and five heavy metal elements, such as cadmium (Cd), lead (Pb), zinc (Zn), copper (Cu), and nickel (Ni) were determined using geographic information system and single-factor pollution risk assessment methods to explore the spatial distribution of soil heavy metals and the impact of soil heavy metal pollution on the quality and safety of Coix seeds.[Results] ① The Cd, Pb, Zn, Cu, and Ni contents in the soil ranged from 0.01 to 1.35, 10.09 to 34.70, 80.39 to 236.36, 22.54 to 131.42, and 26.75 to 137.76 mg/kg, respectively, of which the maximum values of Cd, Cu, and Ni were higher than the current national standard (GB15618-2018), indicating that there was a certain range of Cd, Cu, and Ni pollution risk in the soil in the study area. The comprehensive pollution index was 1.94, and the pollution level was light pollution. ② The contents of Cd, Pb, Zn, Cu, and Ni in the Coix seed ranged from not detected to 0.027, 0.179 to 1.348, 42.615 to 58.961, 10.028 to 16.244, and 0.552 to 5.045 mg/kg, respectively. Cd did not exceed the standard, while Pb, Zn, Cu, and Ni exceeded the standard by varying degrees, with the exceeding rates being 90%, 25%, 75%, and 30%, respectively. Coix seed had a strong cumulative effect of Pb.[Conclusion] By simultaneously collecting soil samples and corresponding Coix seed samples, the analysis results can be used to evaluate the impact of soil heavy metal pollution on the quality and safety of Coix seed.

Abstract:[Objective] The current situation and annual dynamic change of wind erosion on cultivated land in the Yellow River alluvial area of the Huaihe River basin were studied to provide a scientific basis for regional wind erosion research and control.[Methods] Lankao County, He'nan Province, was selected as the research area to interpret the land use information in 2018 and 2019 using high-resolution remote-sensing images. The wind erosion model of cultivated land was used to calculate the modulus of wind erosion, and the effects on wind erosion of cultivated land of annual land-use change were analyzed.[Results] ① In 2018-2019, the major type of land use at Lankao County was irrigated land, and the area of land use change was 21.40 km². The dynamic degree of irrigated land was -1.54%. The main change in land use was from irrigated land to forest land (7.19 km²). ② The main wind erosion intensity on cultivated land at Lankao City was mild erosion, followed by light erosion. The erosion area was reduced by 17.04 km², and the dynamic degree was -12.13%. ③ During 2018-2019, the changes in wind erosion on cultivated land at Lankao County were closely related to the changes in the area and spatial location of the irrigated land. The area of erosion reduction caused by the rotation of irrigated land was 3.36 km², mainly located in Yifeng Township, Chengguan Town and other areas. The area increased by 0.98 km² due to the transfer of irrigated land, which was mainly located in Yifeng township, Putaojia Town and other areas.[Conclusion] The characteristics of land use and wind erosion on cultivated land in the Yellow River alluvial area of the Huaihe River basin are distinct, and the changes in irrigated land directly affect cultivated land wind erosion. Therefore, more attention should be paid to controlling the wind erosion of cultivated land and using the cultivated land effectively.

Abstract:[Objective] The spatial and temporal evolution characteristics of total nitrogen (TN) and total phosphorus (TP) pollutants in the Bahe River basin and their load relationship with annual runoff were explored, and the spatial distribution law of pollution loads was proposed to provide guidance for watershed planning and control.[Methods] Based on the land use data for 1996 and 2017 and the rainfall data of the Bahe River basin from 2001 to 2017, the current-situation simulation and scenario design were carried out based on GIS technology and the AnnAGNPS model.[Results] ① Comparing the land-use-type data in 2017 with 1996, the areas of forest land and cultivated land type decreased and the areas of construction land and water increased. The property flow quota for construction, the TN load quota, increased, and the TP load quota increased whereas that of the forest type (TN load) and the TP load decreased. For the production flow, the TN and TP loads in the water type were basically unchanged. ② Based on land use data in 2017, the TN pollution load of construction land increased to 16.13 kg/ha compared with that (5.24 kg/ha) in 1996, which partly reflected the severity of urban non-point-source pollution in the Bahe River basin in the past 20 years. ③ The largest areas of runoff were the four sub-basin basins of Bahe River, including the Qingyu River, upper Bahe River, Qinghe River, and Wangchuan River. When the runoff value was greater than 4.00×10⁸ t, the TN and TP pollutant loads were in a high load state. ④ The TP and TN load distributions in the four sub-basins, including the Wangchuan, Kuyu, Daiyu, and Qingyu rivers accounted for 50.32% and 56.09% of the entire river basin, respectively.[Conclusion] At present, non-point-source pollution is the main source of pollution in Baba River basin, especially for urban non-point-source pollution.

Abstract:[Objective] The variation characteristics of desert soil moisture were analyzed to provide a theoretical basis and methodology for remote-sensing monitoring of soil water content in the arid desert of Southern Xinjiang Uygur Autonomous Region.[Methods] The desert soil moisture modeling indicators were constructed based on Landsat 8 data. An optimal 26 spectral index, land surface temperature (T_s), and digital elevation model data (DEM) were selected as modeling factors, and the soil water inversion model was constructed using the partial least squares regression (PLSR), support vector machine (SVM), and random forest (RF) algorithms. After model validation and comparison, the spatial distribution of soil moisture in Kongtailike was retrieved using the optimal model.[Results] ① The temperature vegetation dryness index, NR, GLI, and other 26 preferred spectral indices, as well as T_S and DEM, were significantly correlated with soil moisture. They could be used as indicators for remote-sensing modeling of desert soil moisture in the arid area of Southern Xinjiang. ② Among the three models, the R² of calibration and validation based on the RF model were 0.93 and 0.91, respectively, and the RPD of validation was 3.90, which was the highest. The PLSR model accuracy was the second best, and the SVM model accuracy was the lowest. ③ The surface soil moisture in the study area was retrieved by the RF model, and the characteristics of soil moisture distribution in different ground classifications were noticeably different, especially in the salt crust region.[Conclusion] The comprehensive use of spectral index, environmental factors, and terrain factors could result in the inversion of the soil water content in arid areas with a higher accuracy, providing scientific value for the desertification and ecological environment control in this area.

Abstract:[Objective] The structure form of existing sand barriers was optimized to maximize the sand retention effect, the characteristics of wind and sand flow of inclined inserting-type sand fences along a railway were studied in order to provide a relevant design reference and scientific basis for the prevention and control of wind and sand disasters.[Methods] Based on the Eulerian two-fluid unsteady model, numerical simulations were conducted on inclined inserting-type sand fences with different inclination angles of the insert plate (15°, 30°, 45°, and 60°) but the same porosity (30%).[Results] ① The inclination angle of the insert plate gradually increased, the range of the windward side deceleration zone did not change significantly, and the range of the upper acceleration zone and the leeward side vortex zone gradually increased. The tendency of the windward side airflow to bend downward gradually increased, and the angle between the airflow moving upward on the leeward side and the horizontal wind direction gradually increased. ② Under different wind speeds, the wind speeds around the inclined inserting-type sand fence were U-shaped curves. For the same wind speed, the minimum wind speed in the leeward vortex area was negatively correlated with the inclination angle of the plate.[Conclusion] As the inclination angle of the inserting plate increased gradually, the sand on the windward side gradually increased, and the sand on the leeward side gradually decreased. However, the sand in the 1 H range on the leeward side gradually increased. The distance between the main sand distribution on the leeward side and the sand barrier gradually increased.

Abstract:[Objective] Based on the perspective of equity, the standards and priorities of cultivated land ecological compensation in Northeast China from 2011 to 2018 were quantified to provide theoretical guidance for the ecological protection of cultivated land in the region.[Methods] Based on the ecosystem service value, the equivalent factor and water footprint model were constructed based on a theoretical analysis of farmland ecological compensation behavior and standards.[Results] ① The service value of cultivated land ecosystems in Northeast China was high in the east and low in the west. From 2011 to 2018, all three provinces showed the trend of rising first, then decreasing, and rising again. ② After excluding the ecosystem service value consumed by cultivated land managers and combining the payment capacities of different regions, the cultivated land eco-compensation standards in Heilongjiang, Jilin, and Liaoning Province were lower than those in previous years, and the quota for 2018 should be 5.73×10¹⁰, 3.13×10¹⁰, and 1.33×10¹⁰ yuan, respectively. ③ Considering the economic development level of each province in Northeast China, the priority ranking of eco-compensation was Heilongjiang Province, Jilin Province, and Liaoning Province, from high to low, thereby implying that the cultivated land eco-compensation should be paid first to Heilongjiang Province.[Conclusion] When conducting cultivated land eco-compensation in the future, it is necessary to measure the compensation standard of cultivated land in a scientific and reasonable way and to perfect the compensation mechanism across regions.

Abstract:[Objective] The early warning on the ecological security of watershed land in Fenhe River was studied to provide references for the scientific and rational utilization and sustainable development of watershed land resources.[Methods] The spatial and temporal pattern evolution characteristics and leading factors of land ecological security alertness in the basin from 2006 to 2018 were analyzed using a multiplier model, spatial autocorrelation, and a geographic detector.[Results] ① From 2006 to 2018, the evolution trend of the land ecological security alarm degree in the Fenhe River basin was a parabolic curve with upward opening, and it changed from the "less safe" to the "critically safe" state. ② Spatially, the ecological security alert degree of land was characterized by "large agglomeration and small dispersion" and underwent the process of "decline to increase." ③ The change in spatial autocorrelation of alertness experienced the process of "positive-correlation-negative-correlation-positive correlation," which was basically consistent with the spatial and temporal distribution of the ecological security alertness of the watershed land. ④ The leading factors affecting the land ecological security of the river basin for many years were the level of economic development, investment and governance of environmental protection, and land use efficiency.[Conclusion] In the future, the layout of production, living, and ecological space in the Fenhe River basin should be optimized. The ecological compensation mechanism of the basin should be established. Investment in environmental protection and scientific research should be increased to promote the ecological security level of the basin.

Abstract:[Objective] To explore the intrinsic mechanism of ecosystem service value (ESV) evolution, an optimal allocation model for ecological agriculture with towns and river basins as units was investigated.[Methods] Based on the theories and methods of land use and ecological service value, with the Shima River basin land use data from 2010 to 2020, the Clue-S model was used to simulate the land use pattern in 2025, and the results of land use spatial distribution and optimal allocation under three scenarios of ecological security, farmland priority and construction and development in 2025 were obtained, and the space-time pattern of watershed ESV under each scenario was analyzed.[Results] From 2010 to 2020, the ecological service value of the Dongguan section of the Shima River basin decreased by 1.80×10⁷ yuan, which was mainly converted into cultivated land, forest and orchard. The ESVs were 9.44×10⁷, 9.62×10⁷, and 9.38×10⁷ yuan under the condition of giving priority to the ecological security of the construction and development of cultivated land in 2025. In addition to ecological security, the other two scenarios showed a decline from the ESV in 2020.[Conclusion] In areas with rapid urbanization and a prominent contradiction between ecology and development, the simulation and analysis of watershed ESV is helpful to enhance the understanding of the spatial distribution of ESVs under different development modes and to provide macroscopic reference for land use planning and coordinated development of an ecological economy.

Abstract:[Objective] The germination ability of Artemisia desertorum seeds under salt and drought stress was investigated to provide a reference for artificial cultivation and planting of A. desertorum.[Methods] Using A. desertorum seeds as experimental materials, different concentrations of NaCl solutions (0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, and 1.8%) and polyethylene glycol (PEG) solutions (5%, 10%, 15%, 20%, and 25%) were applied to simulate salinity and drought stress conditions on seeds. The germination rate, germination potential, germination index, and vigor index were measured in the early stage of seed germination.[Results] When the NaCl concentration was ≤ 0.6%, the above-mentioned indices did not change significantly compared with the control group. However, when the solution concentration was higher than this range, the indices decreased significantly with the increase in concentration. The NaCl solution concentration of 0.6% was the most suitable concentration limit for normal seed germination. When the PEG concentration was ≤ 15%, the above indices of A. desertorum seeds did not change significantly compared with the control group. However, when the PEG concentration was higher than 15%, the seed indices decreased significantly compared with the control group. The PEG concentration of 15% was the most suitable concentration limit for normal germination.[Conclusion] A. desertorum seeds showed tolerance to mild and moderate salt and drought stress and could still grow normally in low salt content soil and mild and moderate drought environments.

Abstract:[Objective] The contact angle hysteresis characteristics of silty particles were studied to understand the interface characteristics in the process of soil humidification or dehumidification, as well as to provide the corresponding experimental basis for the establishment of a discrete element contact model.[Methods] The initial contact angle and dynamic contact angle on the surface of soil particles were measured by the sessile drop method, and the contact angles between soil particles and pore water under the condition of humidification and dehumidification were measured by the direct observation method.[Results] The average initial contact angle of the natural silty soil was 41.5°, which was much greater than 0. Only one of the three methods widely used for measuring the dynamic contact angle of a continuous surface solid can measure the dynamic contact angle of the surface of soil particles with a receding contact angle of three soil samples greater than 0. The initial contact angle had little influence on the change rule of the contact angle between the soil particles and pore water during the process of evaporation (dehumidification). The change rule of the contact angle between different soil particles in the dehumidification process of the same sample was not consistent, and the contact angle may even change from small to large in the dehumidification process. The humidification modes of hydrophilic and hydrophobic soil were quite different. In the humidification process, pore water first formed a liquid bridge and then formed a liquid film covering the hydrophilic soil particles, while repellent soil first formed liquid droplets on the surface of the soil particles and then connected the droplets to form a liquid film covering the soil particles.[Conclusion] The contact angle of soil particles lags significantly, and the contact angles between the soil particles and the surfaces of the soil particles are not consistent. Therefore, the contact angle must be strictly distinguished in practical applications.

Abstract:[Objective] The applicability of soil water assimilation products at different depths was evaluated to provide a scientific basis for the selection of soil water data for studies on climate change and ecological environment construction in the Western Sichuan Plateau.[Methods] Taking the soil moisture value of the automatic meteorological observation station as a reference, the accuracy of the soil moisture products of CMA land data surface assimilation system (CLDAS-V 2.0) and global land data surface assimilation system (GLDAS-Noah) in the Western Sichuan Plateau was evaluated and the response of soil moisture products to the precipitation process and the effect of precipitation on the soil were analyzed.[Results] ① GLDAS and CLDAS data had an extremely significant correlation with the reference value (p<0.01), and the correlation between the GLDAS data and reference value was generally better than that of the CLDAS data. ② The errors of two sets of soil moisture products in the surface and shallow layers of the study area were small. The error of surface soil moisture was greater than that of the shallow layer, and the error of the GLDAS data was smaller than that of CLDAS data. Both sets of data overestimated soil moisture and the overestimation of soil moisture in the case of no precipitation was more prominent than that in the case of precipitation. ③ The two sets of data showed the same change process as precipitation in the surface layer and shallow layer, and the change in soil moisture lagged behind the change in precipitation. The response of the GLDAS data to precipitation change was more sensitive than that of the CLDAS data, but the CLDAS data had better spatial resolution than the CLDAS data in the spatial distribution characteristics of soil moisture in the Western Sichuan Plateau.[Conclusion] The applicability of the two sets of soil moisture products in surface and shallow layers in Western Sichuan Plateau is good. The quality of GLDAS data is generally better than that of CLDAS data, but CLDAS data have more advantages in the performance of spatial differentiation of soil moisture.

Abstract:[Objective] The land use change in Hami City, Xinjiang Uygur Autonomous Region, over the past 20 years was studied to provide strong support for land use planning and ecological environment protection.[Methods] Based on the GlobeLand 30 datasets in 2000, 2010, and 2020, the spatial-temporal change characteristics of land use in Hami City from 2000 to 2020 were analyzed using a transfer matrix, a slope distribution index, a standard deviation ellipse, and the land use and use center-of-gravity migration.[Results] ① The land use change was obvious in Hami City from 2000 to 2020. The proportion of land use types in 2020 was in the order of unused land > grassland > cultivated land > forest > construction land > water area. Although Hami occupied a large area, the usable oasis area was small. In 2020, the grassland area was 10 226.39 km², and the water area had the smallest proportion, with an area of 295.17 km². In terms of land use type change from 2000 to 2020, grassland had the largest reduction, and the loss area was 671.48 km². It was mainly converted into unused land, forest, and a small amount of cultivated land. The increase in construction land was the largest, with an area of 405.60 km². From 2000 to 2020, the area of forest and cultivated land showed an increasing trend, while the unused land and water areas showed a decreasing trend. The reduction of water area was very small, and the area remained stable. ② From 2000 to 2020, grassland was evenly distributed on the five slope gradients. The cultivated and construction land were distributed in grade Ⅰ and grade Ⅱ slope gradients, and cultivated land was dominant in grade Ⅰ slope gradient. The area of forest was the largest on grade Ⅰ gradient. The distribution area of unused land decreased with the increase in the slope gradient. ③ Compared with 2000-2010, the land use change in 2010-2020 had a more obvious directionality and wider range, and the center of gravity shifted to the northwest.[Conclusion] From 2000 to 2020, the land use change of Hami City had obvious space-time characteristics, and the influence of the slope on the distribution of various types is significant.

Abstract:[Objective] The variation laws of community characteristics with different planting years were studied in accordance with the initial stage of vegetation restoration of the slope of a coal gangue heap in the arid area of Northwest China to provide the basis for ecological restoration in Wuhai mining area.[Methods] The Meifang coal gangue heap in Wuhai mining area was taken as the research object, and the growth status of vegetation and community stability in the initial stage of vegetation restoration were compared and analyzed by using the method of sampling and surveying the field samples.[Results] ① The number of species increased significantly during the vegetation restoration. There were only four species of natural invasive plants in the second year of restoration; then, the number increased to six in the third year. In the fourth year, the number of species increased to seven, and the dominant species were Halogeton arachnoideus. The number of natural invasive plant species increased gradually, indicating that the community was undergoing a positive succession process. ② The average vegetation coverage, superterrane biomass, and richness index increased by 1.5 times, with an increase in the restoration years from two to four, indicating that the community structure was gradually becoming stable. ③ The community of the coal gangue hill was in the initial stage of succession when the vegetation was reconstructed for two to four years. The similarity coefficient of community decreased year by year, and the community structure tended to be complicated, but it was still in an unstable state.[Conclusion] In the following vegetation restoration of coal gangue hill, naturally permanent planting of local species that are adaptive for local conditions should be properly promoted when planting typical reclamation plant species, such as Leguminosae, Gramineae, and Compositae. In addition, the local gene bank should be preserved in the coal gangue hill by planting native plant species belonging to the climax stage of succession.

Abstract:[Objective] The variation in water conservation capacity in different stands was studied to provide a theoretical basis for the restoration of the water conservation function and ecosystem services in Southern Jiangxi Province.[Methods] All experiments were conducted in Chongyi County, Ganzhou City, Jiangxi Province. Two main natural forests, Phoebe zhennan and Phyllostachys heterocycla, and two typical artificial economic fruit forests, Citrus sinensis and Camellia sinensis, were selected. The water holding capacity of the litter layer and soil layer was measured by the water immersion and double ring methods. Related indices of the litter layer and soil layer were evaluated by the entropy weight method.[Results] ① The litter volume, maximum water holding capacity, and effective interception capacity of the four kinds of stand were 9.19-16.70, 13.43-31.02, and 6.99-14.08 t/ha, respectively. The average ranges of soil noncapillary porosity, effective water holding capacity, and maximum water holding capacity were 5.49%-10.05%, 57.98-100.50 t/ha, and 447.76-580.17 t/ha, respectively. All traits in the P. zhennan forest were found to be greater than in the other stands, and the lowest were in the C. sinensis forest. ② Four stands had similar changed tendencies of soil initial infiltration rate and stable infiltration rate. The order was P. heterocycla forest > P. zhennan forest > C. sinensis forest > C. sinensis forest. ③ The comprehensive scores of the water conservation capacity of the natural forests (P. zhennan forest and P. heterocycla forest) were higher than those of the economic forests. ④ The water conservation capacity of the stand was mostly affected by soil steady infiltration rate, followed by maximum water holding capacity and effective retention capacity of the litter, while the soil bulk density was the lowest.[Conclusion] The water conservation capacity of natural forests is higher than that of economic fruit forests in the hilly area of South Jiangxi Province. The land degradation and accelerated soil erosion are driven by the reduction of the water conservation capacity of artificial economic forests in this area, leading to an important ecological risk to the sustainable development of this region.

Abstract:[Objective] The impact of construction waste aggregate on the environment was studied to provide a basis for the application of reclaimed aggregate of construction waste in the water storage structure of sponge cities.[Methods] The particle fragmentation, compression deformation, and water storage rate change of the building waste recycled aggregate at different ratios and different moisture contents were studied through an indoor large-scale compression solidification test, and the environmental impact of the construction waste materials was studied using a leaching toxicity test.[Results] The recycled aggregate had a crushing trend in the compression process, and the degree of crushing of waste brick recycled aggregate was greater than that of waste concrete recycled aggregate. When the moisture content increased from 3% to 12%, the particle crushing rate increased from 121.73% to 132.64%. When the moisture content increased from 12% to 15%, the particle crushing rate decreased from 132.64% to 127.6%, reaching the maximum value near the optimal moisture content (11.56%). The water content affected the compression deformation of the recycled aggregate by affecting particle breakage. The change trend of particle breakage was consistent with the curve of the heavy compaction test. The optimal moisture content can be used to guide the water content control of the water storage structure, reduce particle breakage, and improve the water storage capacity and carrying capacity of the structure. The aggregate of construction waste in different areas had different impacts on the environment, so the reuse of the polluted construction waste should be avoided in the application.[Conclusion] The recycled aggregate of construction waste can be used for the construction of water storage structures in sponge cities. However, it is necessary to distinguish the sources of construction waste to ensure that the materials are free of pollution to the environment.

Abstract:[Objective] The vulnerability of regional groundwater in Yinchuan City was examined to provide a scientific basis for the construction, planning, and protection of groundwater resources in cities.[Methods] The urban area of Yinchuan City inside the beltway was considered as the study area. According to local hydrogeological conditions, six evaluation factors, such as depth to water, recharge of precipitation, water yield properties, soil type, impact of the vadose zone, and aquifer hydraulic conductivity, were selected. The corresponding weight was calculated by the analytic hierarchy process (AHP) to establish the DRASTIC model for groundwater vulnerability assessment.[Results] ① The overall performance of groundwater vulnerability in Yinchuan City was medium-weak. The weak area was located in Xixia District, and the strong area was located in the northern part of Jinfeng District. ② The evaluation results were consistent with the pollution characteristics of NO^-₃.[Conclusion] Groundwater vulnerability assessment is an important means to protect groundwater resources. The Yuehai Lake area in the northern part of Jinfeng District can be used as the preferred area for urban expansion in the future.

Abstract:[Objective] A comprehensive control model of soil and water loss at the reserve zone of the upstream area in Niulan River basin was analyzed to provide new ideas for a water and soil loss control in the basin.[Methods] The subbasins were extracted automatically using ArcGIS based on digital elevation model data. Then, the subbasin was merged and revised manually with the assistance of remote-sensing images. Every subbasin that was determined with the human-computer interaction method was scored using qualitative and quantitative methods to calculate a comprehensive score. The zones of soil and water conservation and their dominant functions were obtained according to the comprehensive scoring of each subbasin. The control model of a "four-type" small watershed was proposed by analyzing the dominant functions of all the zones of soil and water conservation.[Results] The reserve zone of the Niulan River upstream area was divided into nine subbasins and four areas. The "four-type" small watershed management model was set up in the reserve zone of Niulan River upstream area; moreover, the four partitions of soil and water conservation were matched with the "four-type" control model, comprising the types of ecological security, ecological landscape, ecological economy, and ecological cleanness.[Conclusion] The subbasin can be used as the basic unit of the "four-type" small watershed in the upstream protection area of Niulan River basin, and the dominant functions of soil and water conservation can be used as the basis for the configuration of the "four-type" small watershed model. It provides a scientific control model for soil and water conservation in accordance with the type and precision of the partition.

Abstract:[Objective] The heavy metal pollution characteristics and ecological risk for soil were studied to provide a scientific basis for the proper land use in the process of urban renewal.[Methods] Samples of topsoil (0-0.5 m) and subsoil (1.5-2.0 m) were collected from 102 point locations in a large-scale redevelopment site in Shanghai City, and the concentration levels of 10 heavy metals (As, Be, Cu, Pb, Ni, Ti, Zn, Cr, Cd, and Hg) were tested and measured. The heavy metal contamination and ecological risk were evaluated with geo-accumulation, Nemerow, and potential ecological risk indices. The sources of heavy metals were further identified and revealed by multivariate statistical analysis.[Results] ① The contents of the heavy metals in soil were lower than the type Ⅱ land soil risk screening values stipulated in the "Soil Environmental Quality-Risk Control Standard for Soil Contamination of Development Land, Pilot Version" (GB36600, 2018), but the contents of As, Cu, Pb, Zn, and Hg in soil from 6.9%, 24.5%, 25.5%, 37.3%, and 63.7% sampling points exceed the background values of soil elements, which indicated different degrees of accumulation. The soil in the entire study area generally varies from clean to slightly polluted, with 11.8% and 3.84% of the topsoil and 2.64% and 0.63% of the subsoil moderately and heavily contaminated, respectively. ② The mean value of the comprehensive potential ecological risk index for topsoil was 89.91, representing a medium risk level. Hg in topsoil was the main ecological risk factor in the study area. ③ The concentrations of Ni, Cr, Be, and TI in the soil were mainly controlled by natural sources of weathering of the soil parent material. Pb, Zn, Cu, As, and Hg contents in soil were mostly affected by sources of transportation and historical agricultural production activities. Natural sources also contributed a considerable proportion to the contents of As in topsoil and Cu in subsoil as well as man-made sources. Hg in topsoil was more affected by other human activity sources than transportation sources.[Conclusion] During subsequent land use processes, more attention should be paid to the ecological risk control of Hg and the cumulative effect of heavy metals caused by external traffic sources.

Abstract:[Objective] The coordinated relation between the productive-living-ecological functions of Guangxi Zhuang Autonomous Region land space was explored to provide a scientific basis for the coordinated development and regulation of the region.[Methods] The multifactor comprehensive evaluation method was used to evaluate the utilization degree of the productive-living-ecological function from 2009 to 2018, and the coupling coordination model was applied to analyze the change characteristics and coupling coordination relation among the three founction.[Results] ① From 2009 to 2018, the score of the production-living-ecological function showed an upward trend, among which the life function changed the most and the rising range of each prefecture level city was not the same. ② The coupling index of the production-living-ecological function of Guangxi's land space was growing slowly, the distribution of the coordinated development degree was uneven, and the rising span of coordination levels of different cities was different. ③ The spatial distribution of productive-living-ecological function coupling coordination in the western region was larger than that in the eastern region, and that in the coastal area was greater than that in the inland area.[Conclusion] The productive-living-ecological function of Guangxi's land space has been greatly improved, and the development speed in each city is different. The spatial differentiation shows the characteristics of being high in the northeast and southwest, and low in the northwest and southeast, and there is a certain relation between the production and life functions. The positive interaction of the productive-living-ecological function of Guangxi's land space is becoming increasingly strong, and the spatial differentiation is evident from the west to the east with the characteristics of a gradual increase. The imbalance of development among cities is significant.

Abstract:[Objective] The border zone of China, Laos, and Myanmar were used as an example to provide the basis for the rational use of land resources and the reduction and prevention of ecological risk in this area through the evaluation of the development process and ecological status of land use/cover.[Methods] Based on the remote sensing image data of land use/cover in the study area, the evolution process and ecological status of land use/cover in the 12 years from 2005 to 2017 were measured by building models, such as land-use/cover change trend and state index models.[Results] ① The study area was dominated by forest and cultivated land, and the consistency of land-use combination was strong. However, because this area is the border zone of several countries, the degree of land use in this area had some national differences. ② Over time, the structure and change range of land use in the study area underwent significant spatio-temporal and land-type differentiation. The forest land expanded significantly, the cultivated land decreased significantly, and the area of grassland and water changed relatively smoothly. The land-use change in the last six years of the study period was higher than that in the previous six years. ③ During the 12-year study period, the overall land-use change in the study area was unbalanced, and the change trend and status of different land types were significantly different. Over time, the stability of land-use change in the study area was enhanced because of the weakening of forest-land extension and expansion, but the change trend and status difference between different land-use types slightly increased. ④ Over time, the ecological status of the study area improved as a whole, and the country-specific and spatial differentiation decreased. During the 12-year study period, the ecological status of the Laos section showed the most improvement, followed by the Myanmar section and the Chinese section. The distance between the high-value zone of the ecological comprehensive function and the junction of the three countries decreased as a whole.[Conclusion] The evolution process and ecological status of land use/cover in the study area have certain characteristics of national differentiation and stage change. China, Laos, and Myanmar are continuously improving the ecological background function of their border zone.

Abstract:[Objective] The ecological footprint was calculated and the driving factors in China's continental coastal zone was analyzed in order to provide a reference for ecological civilization construction and sustainable development.[Methods] Based on the three-dimensional ecological footprint expansion model, the ecological footprint, biological capacity, and footprint depth of China's mainland coastal zone from 2008 to 2017 were calculated. The sustainable development of China's coastal zone was analyzed in terms of time and space, and the driving factors were analyzed using the partial least-squares method.[Results] ① In the 10 years from 2008 to 2017, the total biological capacity and the per capita ecological footprint of China's coastal zone increased yearly. In terms of component contribution, the per capita ecological footprint of energy fossil land was the largest. ② From 2008 to 2017, the per capita biological capacity did not vary significantly. Among all provinces and cities, the per capita biological capacity of Guangxi Zhuang Autonomous Region was always the largest, while that of Shanghai City was always the smallest. ③ The depth of the footprint showed a trend of increasing year by year, and the depth was greater than 1, which consumed the natural capital stock and aggravated the ecological deficit. From the perspective of space, the depth of the per capita footprint was generally large in central and northern provinces, while the depth of the per capita footprint in Southern Guangxi, Guangdong, and Fujian provinces was relatively low. ④ Economic development, urban scale, environmental pollution, and interregional communication were the driving factors that lead to an increase in ecological footprint and footprint depth. Ecological construction and the improvement of science and technology played a positive role in alleviating the ecological footprint and increasing the depth of the footprint.[Conclusion] In the future, the sustainable development of China's coastal zones can be realized by adjusting the industrial and population structures, changing consumption patterns, further strengthening ecological construction, and improving the scientific and technological levels.

Abstract:[Objective] In the context of territorial and spatial planning, a reasonable ecological security pattern was constructed to provide references for optimizing the pattern of county territorial development and promoting the construction of urban ecological civilization.[Methods] With reference to the double evaluation work guide, the importance of ecological protection of Ruijin City, Jiangxi Province, was evaluated from the perspective of the importance of ecosystem service functions and ecological vulnerability to identify the ecological source. Based on the actual situation of Ruijin City, appropriate resistance factors were selected to establish resistance by using the least cumulative resistance model to identify ecological corridors and comprehensively construct the ecological security pattern of Ruijin City.[Results] The ecological source area of Ruijin City identified through the evaluation of the importance of ecological protection was 1 562.296 km², accounting for 64% of the study area. The administrative boundary correction extracted 13 ecological nodes, and 21 corridors were identified on this basis. The total length of the corridors was 875.94 km, and the ecological security pattern of Ruijin City, which was like "three nets and one district", was comprehensively constructed.[Conclusion] The ecological security pattern of Ruijin City constructed based on the evaluation of the importance of ecological protection, conforms to the policy tendency. It provides a feasible reference method for the optimization of the land development pattern and the construction of ecological civilization in Ruijin City and similar cities.

Abstract:[Objective] The temporal and spatial characteristics of the coupling and coordination between urbanization and intensive use of urban land in Guangxi Zhuang Autonomous Region (GZAR) were studied to promote the sustainable development of urbanization.[Methods] The entropy method was used to evaluate the coupling and coordinated development relationship between urbanization and urban land intensive use in 14 prefecture-level cities in GZAR from 2009 to 2018. The temporal and spatial differentiation patterns were analyzed based on the coupling model.[Results] ① From 2009 to 2018, the coordinated development of urbanization and urban land intensive use in GZAR prefecture-level cities experienced the evolution process of the running-in phase, antagonism phase, and high-level coupling phase, and the overall coupling and coordination continued to be optimized. ② The degree of coordination was mostly in the state of synchronization and lag, and the development between regions was not balanced. ③ The types of coupling coordination were mostly in categories Ⅳ, V, Ⅶ, and Ⅷ, and the overall level of coupling and coordination was good.[Conclusions] ① From the time scale, the level of coupling and coordination of various cities in GZAR showed a steady upward trend, gradually turning from the antagonism stage to the running-in stage, and the relative development relationship tended to lag behind. ② From the spatial scale, the coupled and coordinated development relationship between the two showed the characteristics of flaky zoning and agglomeration, with obvious geographical differentiation. The level of coupling and coordination in the east of GZAR was higher than that in the west, and the central GZAR region was seen to have developed steadily. Local-level cities should strengthen collaboration, coordinate with high-level cities to drive low-level coupled development cities, and promote the sustainable development of urbanization.

Abstract:[Objective] The relationship between land use change and groundwater total dissolved solids (TDS) in the Yanqi Basin plain from 2005 to 2017 was analyzed to provide a basis for the sustainable use of groundwater and ecological environment development.[Methods] Geographic information system software was used to reclassify the CNLUCC data of Landsat-TM/ETM and Landsat 8 in the Yanqi Basin plain area in 2005, 2014, and 2017. The land was divided into six categories:cultivated land, forest land, grassland, water area, urban construction land, and unused land. A total of 232 sets of groundwater samples collected from the Yanqi Basin were analyzed, and geostatistical methods and overlay analysis modules were used to study the characteristics and spatial distribution of total groundwater dissolved in the study area.[Results] The plain area of the Yanqi Basin was dominated by cultivated land, water, and unused land, accounting for more than 60% of the total area. In 2014, the highest average TDS content of cultivated land was 708.6 mg/L, and the lowest average TDS content of woodland was 680.4 mg/L. In 2017, the highest average TDS content of urban construction land was 521.6 mg/L, and the lowest average TDS content of unused land was 477.4 mg/L.[Conclusion] The average TDS content of each land use type in 2017 was lower than that in 2014, which is because the increase in water area that led to an increase in groundwater replenishment, a slowdown in the expansion of cultivated land, and the desalination of groundwater runoff active circulation zones.

Abstract:[Objective] The water quality change characteristics and driving factors of Youjiamao reservoir, which is a drinking water source of mining area in Northern Shaanxi Province were analyzed to provide a technical support for the protection and treatment of drinking water in similar areas.[Methods] The water quality of Youjiamao reservoir was continuously monitored from 2013 to 2019, and 20 water quality indicators were obtained. The principal component analysis (PCA) and PCA-entropy method were used to analyze the monitoring data.[Results] ① Turbidity, chroma, manganese were the main driving factors of water quality in Youjiamao reservoir, followed by permanganate index and ammonia nitrogen. The primary task of water purification was to remove manganese. ② The water quality of Youjiamao reservoir was the worst in 2014, and was better in 2015 and 2016. Water quality was the best in winter and the worst in summer, which had obvious correlation with the precipitation and temperature. ③ PCA was a feasible method to identify the main driving factors of water quality, which was basically consistent with the calculation result of PCA-entropy method.[Conclusion] Manganese pollution is the key factor for the deterioration of water quality in Youjiamao reservoir, and the manganese concentration is significantly higher in summer. Therefore, water treatment technology should be adjusted or chemicals dosage should be increased to meet the drinking water safety.

Abstract:[Objective] The characteristics and driving force of land use change in the border zone between Guangxi Zhuang Autonomous Region of China and Vietnam were explored to provide a basis for the optimization of land structure utilization.[Methods] The spatial-temporal characteristics of land use change in the China-Vietnam border zone of Guangxi Zhuang Autonomous Region from 1980 to 2018 were analyzed using the land use dynamic index, land use change matrix, and Moran index. A multiple linear regression model was built to explore the driving force.[Results] ① The comprehensive land use dynamic degrees of the China-Vietnam border zone of Guangxi Zhuang Autonomous Region during the periods of 1980-2000, and 2000-2018 were 0.43% and 4.50%, respectively. Before 2000, the land use change was relatively mild, and the pace accelerated thereafter. ② Land-use-type transfer occurred for all the lands. In the stages of 1980-2000 and 2000-2018, the overall transferred land acreages were 4 775.92 and 46 730.06 hm², respectively. In addition, the construction land and water area expanded, and the arable land, woodland, grassland, and unused land decreased. Moreover, 9 134.47 hm² was added to the construction land, and 90% can be traced back to arable land, woodland, grassland, and unused land. ③ The types of land in the China-Vietnam border zone of Guangxi Zhuang Autonomous Region showed an obvious positive spatial autocorrelation and a relatively high space agglomeration effect, and changes and transfers occurred in the regional space due to agglomeration effect. ④ A principal factor contributing to the land utilization change in the area was border trade, which was accompanied by population, economy, policy, and other factors affecting the land use change in the China-Vietnam border zone of the Guangxi Zhuang Autonomous Region.[Conclusion] The land use change in the China-Vietnam border zone of the Guangxi Zhuang Autonomous Region has obvious spatial differentiation characteristics. With the acceleration of border opening and development, the evolution of land use patterns accelerated.

Abstract:[Objective] The temporal and spatial distributions of water quality in a typical basin of rare earth mining areas in the Upper Ganjiang River were analyzed to reveal the change and causes of water pollution and provide a theoretical basis and data support for water environment governance.[Methods] Three methods-descriptive statistical analysis, water pollution index, and correlation analysis-were used to analyze the six water quality indicators of 10 monitoring sections in the Taojiang River basin from 2014 to 2017.[Results] ① The pollution status of each monitoring section of the Taojiang River basin in various hydrological periods was different, and the temporal and spatial differences in ammonia nitrogen content were the most obvious. ② The evaluation results of the water pollution index showed that the water qualities of type Ⅱ and type Ⅲ accounted for 55% and 29%, respectively. The Longtou beach section was dominated by type Ⅴ water, with the worst water quality.[Conclusion] Analysis of the causes of water pollution revealed that ammonia nitrogen was the most dominant pollutant in Taojiang River basin. Rainfall had a significant impact on the water environment in that basin. Moreover, industrial activities, dominated by rare earth mining, as well as various agricultural activities, were important factors causing water environmental pollution.

Abstract:[Objective] The land use change and its influence on coastline change along Laizhou Bay was illustrated in order to provide land use data support for the government and relevant departments in coastline planning.[Methods] The land-use and land-cover change(LUCC) information of the coastwise area of Laizhou Bay and spatial distribution of coastlines from 1987 to 2017 was extracted, and land use degree index was calculated. Then the digital shoreline analysis system (DSAS) was used to calculate the adjacent phase change rate of coastlines. By the tool of overlay in ArcGIS, the factors which influence the change rate and length of coastlines were obtained.[Results] ① The area of aquaculture land, salt farm land and construction land had increased gradually from 1987 to 2017; and the area of inland water had increased on the whole; the area of bare land had decreased; and the area of grassland and cultivated land had increased and then decreased; the change of forest land had not been obvious. ② The land use degree had gradually become stronger, the land use degree with strong grade had changed from scattered distribution to centralized facet distribution. ③ Land use had affected the change rate of coastline in the form of reclamation of the sea. The enclosed sea and artificial making grounds within Laizhou Bay had pushed the coastlines to the sea; The coastline of the Yellow River delta had been pushed to the sea by the sedimentation of the Yellow River and the backsea movement of the coastlines had mainly been affected by seawater.[Conclusion] The land use along Laizhou Bay had changed obviously, and the degree of land use had been getting stronger. Land use affected the change rate of coastline in the form of reclamation of the sea, which made the coastline both advance to the sea and move back to the sea. Bare land and aquaculture land were the leading factors influencing coastline length from 1987 to 2005, while construction land and bare land were the leading factors influencing coastline length from 2005 to 2017.

Abstract:[Objective] The connection of various ecological elements in urban and rural spaces on a mesoscale and the detailed optimization measures of the layout of ecological corridors of Harbin City was explored to realize the linkage between the urban and rural ecosystems, improve regional ecological benefits, and provide a reference for making decisions in relevant ecological planning departments.[Methods] Based on the principles of landscape ecology and GIS technology, important river corridors with large ecological resistance values were used as boundaries. According to the development trend of the city, the research scope of urban and rural spaces on a mesoscale was determined. Through an analysis of the land use changes of Harbin City during 1990-2017, the evolution of coupling modes of various ecological elements on the temporal and spatial scales was obtained, providing directions for the construction and optimization of ecological security patterns. The morphological spatial pattern analysis method was used to identify and evaluate the core area, bridge area, and island patches of the ecological elements of the study area, and important ecological sources were extracted based on the dPC index. Based on the minimum cumulative resistance model, potential ecological corridors were obtained and areas with weak connectivity were planned and supplemented through calculations. The width of the buffer zones of corridors, nuclear density, and ecological break point were obtained and the ecological security pattern was optimized in detail based on the temporal and spatial changes in the ecological coupling mechanism.[Results] Through the change in the coupling mode of various ecological elements on a mesoscale, ecological sources and the detailed optimization measures for the corridors in the urban and rural spaces of Harbin City were determined, and a stable and sustainable ecological security pattern was formed. In this research, the optimized construction measures were summarized according to local conditions.[Conclusion] Fifteen core areas in Harbin City are the original ecological sources, and there are 42 important ecological corridors and 63 general ecological corridors. The corridors are mainly distributed in the northern part of the study area. The optimized ecological security pattern complements 11 ecological sources and 220 potential planned ecological corridors, and the suitable construction width of a corridor is 60 m.

Abstract:[Objective] The response of vegetation coverage to climate change and human activities in Guizhou Province was studied to provide important guidance for restoring the regional ecological environment.[Methods] Based on MODIS13 A1 data and meteorological data, the spatio-temporal variation in the normalized difference vegetation index (NDVI) during 2001-2018 in Guizhou Province was analyzed. Moreover, the impact of climate change and human activities on the NDVI was explored with linear trend analysis, partial correlation, and residual methods.[Results] ① The NDVI showed a significant upward trend at a growth rate of 0.005 3 per year in Guizhou Province during 2001-2018. In the space studied, the extremely significant and the significant improvement areas accounted for 52.80% and 16.80% of the study area, respectively. ② The climate showed a process of distinct warming and increasing humidity in Guizhou Province during 2001-2018. The NDVI was positively correlated with temperature and precipitation, and the NDVI was more sensitive to temperature than to precipitation. ③ There was no lag in the response of NDVI changes to temperature on a monthly scale, but there was a one-month lag in the response to precipitation. The correlation between the NDVI and climate change on a monthly scale was higher than that on an annual scale. ④ The effect of human activities on vegetation coverage was increasing in Guizhou Province, and the contribution to the NDVI was 72.30%.[Conclusion] The impact of human activities on the NDVI was greater than that of climate change. The spatio-temporal variation in the NDVI was the result of the combined effects of climate change and human activities in Guizhou Province.