Abstract:[Objective] The rules of land preparation measures on sediment production and non-point source pollutant output of sloping land were analyzed in order to provide a scientific basis and technical support for controlling soil and water loss and agricultural non-point source pollution of sloping land at the source. [Methods] The runoff plots of sloping farmland (15° and 22°) with equi-height reverse slope steps were taken as the research object in Songhuaba at Yizhe watershed experimental area of Kunming City, central Yunnan Province. Rainfall, runoff, and water quality data from 2019 to 2021 were analyzed using a comparative analysis method. The characteristics of flow production, sand production, and nitrogen and phosphorus output of surface source pollutants within the sample plots were studied. [Results] Contour reverse slope terraces used on sloping land with a slope of 22° had more significant effects on the reduction of slope flow and sand production, and the output of surface pollutants nitrogen and phosphorus than land with a slope of 15° under the same rainfall pattern. [Conclusion] Contour reverse slope terraces had significant control effects on sediment yield and non-point source pollutant output on sloping land, and can effectively increase soil and water conservation ability on sloping land, especially on large slopes.

Abstract:[Objective] The influences of surface tension fractures caused by coal mining subsidence on the soil quality of cultivated land were analyzed, and the changes in soil nutrients before and after coal mining subsidence were quantified, in order to provide a theoretical basis for the pre-mining and in-mining management of land in the subsidence area. [Methods] The study was conducted in the surface tension fracture area of the Suntuan Mine in the Huaibei mining area. Samples were collected before subsidence (April 2019), and after sibsidence (December 2019, July 2020). Five sampling points were randomly located before subsidence. Two typical longitudinal tension fractures were selected after subsidence, and the subsidence area was divided into three zones from the top to the bottom of the subsidence slope. Thirteen sampling points were located on both sides of each fracture. At each sampling point, one soil sample was collected every 20 cm of soil depth. Sample collection was completed in December 2019 and July 2020. Six soil indicators were monitored: water content, organic matter, fast-acting potassium, fast-acting phosphorus, total nitrogen, and total phosphorus. [Results] There were significant differences in soil moisture content, organic matter, available potassium, and total phosphorus between the two samplings in the tension fracture area (p＜0.01), but there were no significant differences in available phosphorus and total nitrogen (p＞0.05). Principal component analysis showed that the first principal components were organic matter, total nitrogen, and total phosphorus (positive), and the second principal components were water content and fast-acting potassium (negative). Based on the comprehensive nutrient evaluation-principal component score analysis, the integrated nutrient score increased with time. However, the nutrients in the tension fracture zone gradually increased from the top to the bottom of the subsidence slope. [Conclusion] Surface tension fractures were widely distributed in the coal mining subsidence area, leading to a decline in soil quality.

Abstract:[Objective] The effects of fertilization and mixed sowing on soil nutrients and pasture yield of degraded grassland in the Songnen Plain, Western Heilongjiang Province were studied, in order to provide a scientific basis for restoration of natural degraded grassland in local area. [Methods] The study was conducted on a natural lightly degraded grassland in the Songnen Plain of Western Heilongjiang Province. Astragalus adsurgens and Elymus dahuricus were used as reseeding grasses. Treatments consisted of two interrow mixed sowing ratios 〔legume:grass ratio 2∶2 (B₁) and 1∶2 (B₂)〕,and six nitrogen, phosphorus, and potassium application rate combinations: N₅₀P₄₀K₄₅(A₁), N₁₀₀P₂₄₀K₂₂₅(A₂), N₁₅₀P₀K₁₈₀(A₃), N₂₀₀P₁₂₀K₀(A₄), N₂₅₀P₈₀K₂₇₀(A₅), and N₃₀₀P₂₀₀K₉₀(A₆), where subscripts after each element indicated the application rate given as kg/hm² N, P₂O₅, and K₂O, respectively. [Results] Fertilization significantly improved available nutrients and pasture yield based on the ratio of mixed sowing. Soil nutrient changes in the surface soil layer (0—10 cm) were more affected by fertilization and mixed sowing than in the deeper layer (20—30 cm). Fertilization, mixed sowing, and their interaction had significant effects on the content of available soil nitrogen (p＜0.05). The variation trends of available nitrogen and available phosphorus in the 0—10 cm soil layer were basically consistent with the additions of nitrogen and phosphorus. The contents of total nitrogen, available nitrogen, and available phosphorus in the 0—10 cm soil layer of legume-grass mixture in the 1∶2 ratio were greater than in the 2∶2 ratio at the same fertilization level. The productivity of the high nitrogen treatment (A₆) was significantly (p＜0.05) greater than that of the other treatments. The greatest aboveground biomass values were observed for the legume-grass 2∶2 ratio + N₁₅₀ P₀K₁₈₀ treatment combination (290.68 g/m²) and for the legume-grass 1∶2 ratio + N₃₀₀P₂₀₀K₉₀ treatment combination (254.31 g/m²). [Conclusion] Considering pasture yield and changes in soil nutrients, the legume-grass mixed sowing in the 2∶2 ratio and the fertilizer application rate of 150 kg/hm² for nitrogen can be recommended.

Abstract:[Objective] The differences in aggregate stability and infiltration characteristics of loess under different forest and grass vegetation restoration types were compared in order to provide a theoretical basis for the optimization of ecological restoration patterns in the Loess Plateau. [Methods] Abandoned land (C₁, control), alfalfa land (C₂), natural grassland (C₃), mixed forest land of Pinus tabuliformis and Platycladus orientalis (L₁), and mixed forest land of Robinia pseudoacacia and P. orientalis (L₂) were used to investigate differences in aggregate stability and infiltration characteristics and their exogenous factors. Water-stable aggregate composition and saturated hydraulic conductivity were determined by the Savinov method and a single-ring two-ponding depth infiltrometer, respectively. Mean weight diameter (MWD), geometric mean diameter (GMD), fractal dimension (D), percentage of aggregate destruction (PAD), water-stable macroaggregate content (＞0.25 mm, M_w), and saturated hydraulic conductivity sample (K_s) were used as evaluation indicators. [Results] ① In the 0—30 cm soil layer, C₁ had the lowest GMD and MWD, and GMD and MWD in forest and grass vegetation restoration types followed the order of 〔L₁ and C₃〕＞〔L₂ and C₂〕, respectively, whereas PAD and D showed the opposite order. ② In the 0—10 cm soil layer, L₁ dominated the highest macroaggregate (＞0.25 mm) content (47.24%), followed by C₃ and L₂, while C₁ had the lowest content (24.00%). In the 10—30 cm soil layer, C₃ dominated the highest macroaggregate (＞0.25 mm) content (35.41% at 10—20 cm; 27.96% at 20—30 cm), while L₂ had the lowest content (11.46% at 10—20 cm; 8.00% at 20—30 cm). ③ The variation coefficients of topsoil infiltration characteristics for different restoration types ranged from 0.001 to 0.360. The K_s (0.307 cm/min) of L₁ was the highest, while the K_s (0.044 cm/min) of C₁ was the lowest. ④ Aggregate stability indicators (except PAD) and K_s were significantly correlated with soil organic carbon, porosity, and bulk density. [Conclusion] The restoration of forest and grass vegetation was beneficial for improving aggregate stability and infiltration performance. Compared with natural grassland, long-term forest restoration exhibited better aggregate stability and infiltration characteristics, but those characteristics were worse for short-term forest restoration than for natural grassland. Time accumulation should be emphasized when evaluating the effects of vegetation restoration.

Abstract:[Objective] The soil and water conservation effect mechanism of the two core elements (slope and vegetation) in a slope-to-terrace project were systematically analyzed to provide specific methods for multi-index mechanism research, to supplement and improve the ecological effect theory of water conservation projects, and to provide theoretical guidance for the practice of ecological civilization construction. [Methods] Slope and vegetation factors were comprehensively considered, and a variety of mathematical models were used to deeply analyze their water conservation effect mechanisms. [Results] ① Based on a linear model, the linear component decomposition of the total soil and water conservation effect of the five indicators in the full text under the same spatiotemporal conditions was realized. Furthermore, based on the precise calculation of the relative contribution rate of each component, the real source of the soil and water conservation effect of the slope-to-terrace project was revealed for the first time in a theoretical sense. ② Based on multiple regression analysis, the optimal mathematical model was selected from a large number of alternative models, and the specific influencing factors and mechanism of the soil and water conservation effect of the above components were profoundly revealed. ③ Based on structural equation modeling (SEM), the rationality of the specific theoretical model including two latent variables (physical factor and chemical factor) reflecting the soil and water conservation effect of the five indicators in the full text was verified. By SEM group analysis, the preset models under the two slope conditions were fitted at the same time, clearly and intuitively showing the internal relationship between the factors and the differences in the mechanisms of the soil and water conservation effect under different slope conditions. ④ Based on principle component analysis, a comprehensive factor containing 80.8% of the information of five original variables was constructed, and the evaluation index was changed from five dimensions to one dimension, so as to realize the overall comprehensive quantitative evaluation of soil and water conservation effects. [Conclusion] Based on advanced data analysis methods, deep integration of research conclusions on the mechanism of the multi-factor soil and water conservation effect can be achieved, which deepens people’s understanding of its specific mechanism. It can also provide a methodological reference for the research of multi-index mechanisms, help to build professional mathematical models with higher predictive accuracy, and improve the efficiency of soil and water conservation practice.

Abstract:[Objective] The permeability and shear strength characteristics of purple soil in the Three Gorges reservoir area under the coupling effect of seepage and stress were studied, and the coupling relationship between stress and seepage of purple soil was deeply explored, in order to provide theoretical reference for practical engineering applications such as agricultural engineering, slope engineering and soil and water conservation. [Methods] Changes in shear strength and permeability of purple soil under multi-factor coupling were analyzed using an SLB-1A stress-strain controlled triaxial shear permeability tester. [Results] The influence of water content on cohesion (c) and internal friction angle (φ) of purple soil in the Three Gorges reservoir area was different, and the peak value was obtained at the water content of 11%. The internal friction angle decreased linearly with increasing water content. The permeability of purple soil varied greatly among different water content gradients, and the differences were relatively obvious when the water contents were between 11% and 13%. With the permeability pressure equal to the critical value of 40 kPa, the permeability reduction forms of purple soil were different. The greater the control value of the principal stress difference, the lower the permeability of purple soil with different moisture contents. [Conclusion] Water content and confining pressure greatly affected the shear strength of purple soil under the action of seepage-shear. Cohesion reached a peak value at 11% water content, and the changes of cohesion and internal friction angle were linear. Under the same conditions, the influence of water content and principal stress difference on the permeability coefficient of purple soil with axial stress followed a cubic relationship. The contribution rates of various factors to the permeability of purple soil from high to low followed the order of permeability pressure ＞ principal stress difference ＞ confining pressure ＞ water content.

Abstract:[Objective] The distribution of soil water, salt and nitrogen in arid and semi-arid areas were analyzed in order to provide a basis for preventing and controlling non-point source pollution of groundwater and sustainably utilizing water and soil resources. [Methods] Four typical land use types (forest land, cropland, playa and grassland) in the Bashang area of Hebei Province were selected as the study objects. By analyzing changes in water, salt and nitrate of soils, we determined the distribution patterns of water, salinity, and nitrogen in the soil profiles of the different land use types. [Results] ① The soil water and salt content in the playa of Anguli Lake was the highest among the different land use types, with an average water content of 60.18%. The distributions of soil water and salt showed medium variability, with a greater degree of variability in water content. ② The same distributions of soil water and salt in the 0—220 cm soil profile were observed for forest land, farmland, and the playa (all except grassland) of Anguli Lake, exhibiting an oscillating shape, homogeneous shape, and bottom aggregation shape, respectively. ③ Saltions for the four land use types were significantly different (p＜0.05), and their compositions were dominated by SO^2-₄, while K⁺, Mg²⁺ and Ca²⁺ were relatively scarce. ④ The average nitrate content in the soil profile of the playa of Anguli Lake was as high as 134.18 mg/kg. Its distributions in forest land and farmland exhibited accumulation in topsoil, characterized by less in the middle and more at the top and bottom of the playa of Anguli Lake. The accumulation of nitrate in the upper soil layer of grassland was obvious. ⑤ The nitrate of soils of forest land, cropland, playa and grassland showed highly significant positive correlations with K⁺, which was the main factor that controlled the variation of nitrate. [Conclusion] The distributions of soil water, salt and nitrogen on forest land, cropland, playa and grassland in the Bashang area of Hebei Province had obvious variability, and the soil water, salt, and nitrogen content in the playa of Anguli Lake was significantly higher than seen for the other three land use types, thereby posing a serious risk of leaching to groundwater.

Abstract:[Objective] The improvement effects of chicken manure and slag addition on dredged soil were investigated in order to provide a theoretical basis for resource utilization of dredged lake soil. [Methods] A pot experiment was conducted with dredged soil as the test soil and Pennisetum hydridum as the planted species. Four treatments were established: control (CK, no additions of chicken manure and slag), addition of 5% chicken manure (T₁), 5% chicken manure + 5% slag (T₂), and 5% chicken manure + 10% slag (T₃). The effects of the different treatments on the physicochemical properties of the dredged soil, and on the growth and nutrient uptake of Pennisetum hydridum were analyzed. [Results] All three treatments significantly improved the physicochemical properties of the dredged soil compared with CK. T₃ had significantly lower bulk density and higher total porosity and capillary water holding capacity than the other treatments. Soil organic matter, total nitrogen, total phosphorus, total potassium, alkaline hydrolysis nitrogen, available phosphorus, and available potassium content were all at the highest levels with T₃. The chicken manure and slag additions significantly increased the growth and nutrient accumulation of Pennisetum hydridum, with the T₃ treatment showing significantly greater plant height, biomass, and accumulation of nitrogen, phosphorus, and potassium in aboveground and belowground plant tissues than observed for the other treatments. The results of the comprehensive evaluation by principal component analysis showed that the capacity of the three treatments to improve dredged soil followed the order of T₃＞T₂＞T₁. [Conclusion] The addition of chicken manure or chicken manure + slag significantly improved the physicochemical properties of the dredged soil and promoted the growth and nutrient accumulation of Pennisetum hydridum, and the T₃ treatment had the greatest capacity to improve dredged soil.

Abstract:[Objective] The effects of different factors on the shear strength index and shear strength of the root-soil interface were analyzed, in order to provide an understanding of the mechanism of shrub root soil fixation and slope protection in the loess region of the Northeastern Tibetan Plateau. [Methods] The dominant shrub (Caragana korshinskii) for this region was selected as the study object, and the effects of the dry density, moisture content, and salt content of soil, and of root diameter on the shear characteristics of the root-soil interface and their mechanisms were analyzed and discussed using the direct shear test (i. e., one factor was varied at a time) for root diameters of (2.20±1.00—32.00±1.80) mm and moisture contents, dry densities, and salt contents of the soil of 6.00%—22.00%, 1.20—1.60 g/cm³, and 0.59%—2.50% respectively. [Results] Root diameter had no significant effect on the shear strength indexes and shear strength of the root-soil interface (p＞0.05) when other influencing factors were held constant. As soil moisture content increased from 6.00% to 22.00%, the root-soil interface cohesion initially increased and then decreased, reaching a maximum value of 6.74 kPa at a soil moisture content of 14.00%. The root-soil interface friction angle decreased linearly from 21.40° to 15.75°. The shear strength of the root-soil interface decreased linearly. As the soil dry density increased from 1.20 g/cm³ to 1.60 g/cm³, the cohesion of the root-soil interface increased exponentially from 5.70 kPa to 6.85 kPa, and the friction angle increased linearly from 20.67° to 21.67°. The shear strength of the root-soil interface increased linearly. As the soil salt content increased from 0.59% to 2.50%, the root-soil interface cohesion increased linearly from 6.71 kPa to 7.31 kPa, and the shear strength increased linearly. However, there was no significant change in the root-soil interface friction angle (p＞0.05). The gray correlation analysis of these results showed that dry density had the greatest influence on the cohesion, the friction angle, and the shear strength of the root-soil interface. [Conclusion] The dry density, moisture content, and salt content of soil can all affect the shear characteristics of the root-soil interface, however, the degree of influence is different. The influence of rainfall infiltration on the shear characteristics of the root-soil interface should be fully considered when evaluating the protective effect of plant roots on the shallow soil of loess slopes.

Abstract:[Objective] The effects of different planting and overturning of winter green fertilizer on soil nitrogen supply capacity were studied in order to provide theoretical basis for improving planting technology of winter green fertilizer, increasing crop yield and maintaining soil productivity in North China. [Methods] A field experiment with a winter green manure-maize rotation was conducted at Wuqing District, Tianjin City from 2012 to 2019. The study also included indoor incubation experiments. The treatments included winter fallow, february orchid, vetch, rye, ryegrass, mixed vetch and february orchid, and mixed vetch and rye. Soil organic nitrogen content and its composition, soil organic nitrogen mineralization potential (N₀), and mineralization amount were measured. The effects of winter green manure planting and incorporation on soil organic nitrogen composition and mineralization were analyzed with winter fallow used as the control. [Results] Compared with winter fallow, winter green manure significantly increased total organic nitrogen and acid hydrolysable organic nitrogen by 3.05%—12.36%. However, winter green manure significantly decreased the content of non-acid-decomposed organic nitrogen by 18.87—55.87 mg/kg. N₀ was 189.15—245.90 mg/kg in the treatments with winter green manure (14.16%—48.41% greater than the control), and, half-life was increased by 22.57%—73.11%. After 24 weeks of indoor culture, soil organic nitrogen for all treatments was mainly composed of acid hydrolysable organic nitrogen. The mineralization amount of acid hydrolyzed total nitrogen was 3.41—20.54 mg/kg greater in the winter green manure treatments than that in the control, and the mineralization rate was 7.96%—47.31% higher than that in the control, with significant differences. [Conclusion] Winter green manure planting and incorporation significantly increased soil organic nitrogen storage and mineralizable nitrogen content, and prolonged the mineralization cycle, thereby promoting the renewal of the soil nitrogen pool, and improving soil nitrogen availability.

Abstract:[Objective] The early risk warning prevention and control platform for check dam systems under extreme rainfall conditions were studied for intelligent inspection of dams and protecting check dams from water damage and breakage, in order to provide professional, rapid, and accurate technical support for flood control management and early risk warning. [Methods] We developed a full-coverage and high-efficiency software system through the design and development of functional modules based on iVX language and using MySQL database. We used “family tree” theory and the FT-IWHR analysis program to determine the failure risk of check dam systems, and combined this with engineering practice. [Results] A check dam system early risk warning, prevention and control platform was established. The basic information for a check dam system, the inspection monitoring system, and the early failure risk warning system were applied to the daily risk management of check dam systems in a visual and mobile way. The platform was applied in Xiaogou small watershed, Xiangning County, Linfen City, Shanxi Province. [Conclusion] It is feasible to conduct early risk warning prevention and control in check dam systems through information construction. The method can provide a quick and intuitive information transmission platform that is convenient for staff to operate and manage check dam systems, and effectively prevent the risk of accidents in these systems.

Abstract:[Objective] The spatiotemporal variation characteristics of ecological environment quality and its driving factors in the upper reaches of Zhanghe River basin were analyzed in order to provide a scientific basis for ecological environment construction and management of the region. [Methods] The Landsat images of the upper reaches of Zhanghe River basin from 2000 to 2020 was optimized and reconstructed. Based on remote sensing ecological index (RSEI), three indicators of slope, normalized difference mountain vegetation index (NDMVI) and difference index (DI) were introduced to construct the advanced remote sensing ecological index (ARSEI) model considering the impact of topography and particulate matter. Spatial analysis and statistical methods were used to quantitatively evaluate the ecological environment quality of the study area. [Results] ① ARSEI has good applicability, and can accurately indicate the ecological environment quality in the upper reaches of Zhanghe River basin. NDMVI had the greatest influence on ARSEI, and DI was the least. ② The overall ecological environment quality showed a spatial pattern of “poor in southwest and excellent in northeast”, and the grades were mainly poor or moderate. During the study period, 35.94% of the regions showed improvement, mainly by one grade, of which the improvement from 2010 to 2020 was the most significant, and the change pattern was characterized by “overall stability and local change”. ③ The influence order of different types of factors was model factor ＞ topography factor ＞ meteorological factor ＞ social factor ＞ economic factor. All of the influence factors showed synergistic enhancement, and the interaction of NDSI, NDMVI and slope had the greatest influence on the spatial heterogeneity of ARSEI. [Conclusion] The average value of ARSEI in the upper reaches of Zhanghe River basin showed an overall increasing trend during 2000—2020, and the ecological environment quality was improved. The main driving factors for the change were NDMVI and slope.

Abstract:[Objective] The spatio-temporal evolution of land use patterns in Chongqing City was analyzed in order to provide a scientific basis for promoting the sustainable use of land resources and sustainable social and economic development in the region. [Methods] Remote sensing monitoring data of land use for Chongqing City (located in a mountainous high-density area) from 1995 to 2020 were quantitatively analyzed to determine the spatio-temporal evolution characteristics of land use in Chongqing City from the aspects of quantitative structure and spatial layout. The driving forces of land use change in Chongqing City under different time scales were analyzed by geographical detectors. [Results] The rate of land use change in Chongqing City accelerated during the study period. The land used by urban and rural residents and the land used for industrial and mining construction continued to increase. The grassland area was greatly reduced and concentrated by the conversion to forest land. For 25 years, the degree of land use in Chongqing City has increased year by year, with the entire aera being in the development period. Hot spots of development were mainly concentrated in the main city and its surrounding areas. The density of paddy fields in Western Yuxi District decreased. The high-value density area of forest in Southeast Chongqing City increased, but the high-value density area of grassland decreased significantly. The high-density core of urban and rural residential land was located in the main urban area, and the high-density core of industrial and mining construction land exhibited a sattered distribution having a large growth rate. Socio-economic factors had a significant impact on land use change in Chongqing City, of which population density was the dominant factor. [Conclusion] Regional differences in land use change in Chongqing City were observed over time, and land use change was mainly affected by socio-economic factors.

Abstract:[Objective] The ecological carrying capacity of water resources in the lower reaches of the Yellow River basin was evaluated in order to provide a theoretical basis for regional water resource management and planning. [Methods] The spatial and temporal distribution characteristics and driving mechanism of the ecological footprint of water resources in the lower reaches of the Yellow River basin from 2007 to 2020 were calculated and analyzed using the theory of ecological footprint of water resources and the logarithmic mean Divisia index method (LMDI), The grey forecasting model GM(1,1) was applied to predict the change trend of the ecological footprint of water resources from 2021 to 2030. [Results] The ecological footprint of water resources in the lower reaches of the Yellow River over the study years was much greater than the ecological carrying capacity, and the ecological deficit of water resources was serious. Both the ecological footprint of water resources and the ecological deficit showed a fluctuating and decreasing trend over years, and the efficiency of water use was gradually improving. Agricultural water consumption was the largest factor accounting for the ecological footprint of water resources. The Yellow River Delta was the area with the greatest ecological pressure on water resources in the lower reaches of the Yellow River basin. Zibo, Jinan, Zhengzhou, and Tai’an City had relatively little ecological pressure. The economic effect had a major positive role in the change of the ecological footprint of water resources in the lower reaches of the Yellow River basin, and the technical effect had a major negative role. The forecast results indicated that the ecological deficit of water resources per capita in the lower reaches of the Yellow River basin would decrease from 0.387 to 0.359 hm²/person from 2021 to 2030. [Conclusion] The water use efficiency in the lower reaches of the Yellow River basin has gradually increased over time, and the ecological pressure on water resources has been relieved to a certain extent under the comprehensive effects of rapid development of productivity and optimization and adjustment of water-using structures. However, the sustainable utilization of water resources in the future is still under very serious pressure due to the large deficit in the ecological base of water resources in this region. It is therefore urgent to further strengthen the overall management of water resources in order to help the lower reaches of the Yellow River basin achieve high-quality sustainable development.

Abstract:[Objective] An ecological barrier area that combined positive and negative action areas was constructed to fully realize the protection and defense goals of an ecological barrier in order to provide a reference for scientific planning and implementation of ecological barrier distinction goals and differentiated management. [Methods] Positive and negative effect areas for the Bohai Bay ecosystem were extracted based on a hotspot analysis of waterbird diversity, ecosystem service value assessment, and ecosystem quality evaluation of the nearshore marine ecosystem. In combination with the marine protection planning objectives of each province, the Bohai Bay sea-land coordinated ecological security barrier was finally constructed. [Results] ① The hotspots of waterbird diversity were located in coastal mudflats, wetlands, and water ecosystems. The cold spots were located in areas frequently affected by human activities such as construction land and cultivated land. The ecosystem service value showed an increasing trend from north to south, and the service value of the water conservation function was the highest. ② The overall quality of the near-shore seawater environment was improving, but there were still places with frequent marine disasters such as severe eutrophication and red tides. From north to south, the carrying capacity of the marine environment gradually decreased, and the intensity of marine fishery development slowly increased. ③ The ecological security barrier area consisted of 16 areas, including 11 positive-acting areas and five negative-acting areas. These areas were mainly located at the land-sea intersection on the offshore side, and generally presented the characteristics of interval distribution. [Conclusion] The ecological barrier will be used as a guide to carry out planning and management and ecological governance. The positive-acting areas are aimed at achieving the protection goal, and the negative-acting areas are aimed at attaining the defense goal so as to promote the construction of an integrated ecological civilization on sea and land.

Abstract:[Objective] The Dianchi Lake ecological corridor, the ecological nodes and obstacles were identified, and then the ecological network of the watershed was optimized in order to provide a reference for the maintenance and improvement of the ecological function of the ecological migration corridor in the Dianchi Lake basin. [Methods] The study was conducted for the Dianchi Lake basin. Morphological spatial pattern analysis was combined with circuit theory to identify the ecological sources, pinch points, and obstacle areas in the study area, and to construct an ecological network. At the same time, spatial syntax was introduced to quantify the road network in order to optimize the electrical resistance surface. The back resistance surface and the ecological network were compared to determine the impact of the road network on the ecological network. [Results] ① The overall ecological source area accounted for a relatively high proportion of the total study area. The 17 extracted ecological source areas had an area of 101 248 hm² and accounted for 34.7% of the total area of the study area, mainly located in the northern mountainous area and the central area around Dianchi Lake; ② The optimized high resistance area of the resistive force surface was transferred from the surrounding area to the main urban area, and the number of corridors increased from 35 to 41. The total length increased from 185.9 km to 216.2 km. The degree of network closure, connection degree, and connection rate were increased by 0.20, 0.35, and 0.13, respectively; ③ The corridor width was determined to be 600 m through the threshold analysis of corridor width. 15 116 hm² of ecological pinch points and 71 875 hm² of ecological barrier areas were extracted form the Dianchi Lake Basin ecological safety network. [Conclusion] The fragmentation of ecological patches in the Dianchi Lake basin was obvious, and their distribution showed the characteristics of dense ecological foci in the north and sparse ecological foci in the south. The cutting effect of high-grade and high-traffic roads on the ecological network was very prominent, and these kinds of pinch points and obstacle areas should be given greater attention in the construction and restoration of ecological networks.

Abstract:[Objective] The simulation effects and land use prediction accuracy of three land use transition models (LogReg, MLP, and SimWeight) for multi-land change analysis were compared and analyzed in order to provide a reference for land space planning, soil and water conservation, and ecological restoration in the Yunnan-Guizhou Plateau. [Methods] Three models were used to simulate land use changes for Kunming City from 2000 to 2020. Various methods such as ROC curve, AUC coefficient, and kappa coefficient were used to evaluate model performance. [Results] The simulations of change trends for most land use classes by MLP and SimWeight were better than the simulations by LogReg, especially with regard to the change analysis of unused land where the AUC values for MLP and SimWeight were greater than 0.9. The kappa values for LogReg, MLP, and SimWeight were 0.906 6, 0.904 1, and 0.925 3, respectively. The overall prediction results for the three models were similar, and SimWeight was slightly better than the two other models. [Conclusion] For LUCC modeling of Kunming City, SimWeight is recommended when the user desires higher accuracy, MLP is recommended when the user cares more about calculation speed, and LogReg is recommended when the user wants to further analyze the relationship between driving factors and land use changes.

Abstract:[Objective] The accurate and rapid landslide susceptibility zoning method were studied in order to provide a reference for regional safety monitoring, and provide a scientific basis for the government to control landslide disasters. [Methods] The study was conducted in the Guichi District of Chizhou City, Anhui Province. The coupled model of gradient boosting decision tree-logistic regression (GBDT-LR) and an information value (I) model was used to determine the evaluation of regional landslide susceptibility. The model learns from the original samples and combines them to generate new simulation samples in order to enhance the fitting ability of the model to evaluate landslide susceptibility. The Borderline-Smote algorithm was used to solve the problem of sample data asymmetry. The slope unit divided by r.slopeunits software was selected as the minimum evaluation unit, and a total of 10 evaluation factors were selected: slope gradient, slope aspect, terrain curvature, profile curvature, plane curvature, topographic wetness index (TWI), topographic relief, normalized difference vegetation index (NDVI), distance from fault, and distance from river. The landslide susceptibility model was evaluated from three aspects: frequency ratio, density of landslide disaster points and hidden danger points, and the receiver operating characteristic (ROC) curve. [Results] The experimental results showed that the frequency ratio of the coupled model I-GBDT-LR was 10%, 13%, and 7% greater than that of the I, LR, and I-LR models, respectively. The density of landslide disaster points and hidden danger points in the high risk area increased by about 9, 11, and 7, respectively, and the ROC accuracy increased by about 10%, 9%, and 5%, respectively. [Conclusion] The accuracy of the coupled model was higher than that of the single model, and the accuracy of the coupled model proposed was higher than that of the I-LR coupled model, which provides an effective and new evaluation method for landslide susceptibility evaluation.

Abstract:[Objective] The variation rule of water transparency and the driving factors of its spatial differentiation were analyzed in order to provide a scientific basis for the management of lake reservoirs and the restoration of lake reservoir ecosystems. [Methods] A remote sensing inversion model of water transparency in Pingzhai reservoir was constructed based on sentinel-2 MSI satellite images and quasi-synchronous measured transparency data collected on May 18, August 26, and November 14, 2020. We quantitatively analyzed the drivers affecting spatial differentiation of water transparency using the GeoDetector package in R. [Results] ① The water transparency of Pingzhai reservoir was most sensitive to the B₃ band of Sentinel-2 MSI, and the transparency inversion model constructed by using the band combination B₃×B₄ as the most sensitive factor had high accuracy (R²=0.81，RMSE=0.11 m，MRE=16.91%). ② The water transparency of Pingzhai reservoir showed a spatial distribution trend of high in the central reservoir area, low in the upstream region of each tributary, and low on both sides of the near water body. Water transparency was greatest in November followed by August and then May. [Conclusion] The contents of total suspended solids, chlorophyll a, and total organic carbon were the main factors affecting the spatial differentiation of water transparency in Pingzhai reservoir. Total phosphorus, total nitrogen, water temperature, and wind speed affected the spatial distribution of water transparency by affecting the content of total suspended solids, chlorophyll a, and total organic carbon in the water.

Abstract:[Objective] The key influencing factors of urban ecological water security in Gansu Province were comprehensively evaluated in order to provide a reference for coordinating the relationship between regional ecology, production and life. [Methods] Based on social, economic, ecological, and water resource and development factors, an ecological water use evaluation system was constructed. The weights for each factor were obtained by a combination of analytic hierarchy process (AHP) and the entropy method. The level of ecological water security was categorized, and the main influencing factors of ecological water security were determined. [Results] ① In 2020, the overall ecological water security index values for Jiayuguan, Lanzhou, and Gansu Province were more than 0.5 (the basic safety level), while the values for 12 of the cities were at relatively unsafe levels. ② The level of ecological water security in the core area from 2011 to 2020 was low, mainly affected by the ecological benefits subsystem. ③ The coverage area of green space, proportion of ecological environment water, per capita green space area of parks, and urbanization level were the main obstacles affecting the level of ecological water security, contributing more than 45%. [Conclusion] The ecological water security of each urban area in Gansu Province does not appear to be optimistic, and it will be necessary to improve ecological benefits in order to improve the ecological water security of each urban area in Gansu Province.

Abstract:[Objective] The spatial distribution characteristics of agricultural production, social security, and ecological security of cultivated land in the Zuoyoujiang old revolutionary base area of Guangxi Zhuang Autonomous Region were analyzed at the county level to provide a basis for optimizing the multi-functional allocation of cultivated land, and to promote coordinated regional development. [Methods] The entropy weight method and the coupling coordination degree method were used to calculate a coordination relationship of multifunctional cultivated land in 32 counties of the Zuojiang River in Guangxi by constructing a multifunctional evaluation system of cultivated land. The grey relational analysis method was used to reveal the influence of each index on the multi-functional system of cultivated land. [Results] From 2005 to 2020, the agricultural production capacity and ecological security maintenance capacity of cultivated land in the Zuoyoujiang area of Guangxi continued to increase, and the social security function declined. During the same period, the average value of the multi-functional comprehensive index of cultivated land in the counties of the Zuoyoujiang area of Guangxi exhibited differences, showing a distribution pattern of “high at the edge and low in the middle”. In terms of coupling coordination degree, the three subsystems of functional cultivated land have not yet reached the stage of benign resonance, but they are developing in a positive direction as a whole. The impact of each indicator on the overall function of cultivated land in the Zuoyoujiang area of Guangxi has transitioned from the population, cultivated land resource endowment, and factor input in 2005 to the level of economic development and urbanization in 2020. [Conclusion] In the future, according to the different dominant functions of cultivated land, each county can use cultivated land according to local conditions, so as to promote coordinated development among the multi-functional subsystems of cultivated land.

Abstract:[Objective] The interaction mechanism between intensive land use and new-type urbanization was determined in order to provide a reference for regional high quality development. [Methods] We qualitatively analyzed the interaction mechanism between the “resource-asset-capital” attribute of intensive land use and the “scale-agglomeration-dividend-wealth” effect of new-type urbanization, and set up an evaluation index system. We used survey data from 14 cities in Guangxi Zhuang Autonomous Region from 2003 to 2020 to quantitatively evaluate the development status of two cities by using an entropy method, a coupling coordination model, and a fuzzy comprehensive evaluation method. The panel vector autoregressive (PVAR) model was used to empirically analyze the interaction between the two cities as well. [Results] ① Intensive land use in Guangxi was dominated by resource (0.388) and asset (0.541) intensiveness, and the average composite index increased from 0.104 to 0.318. New-type urbanization was dominated by the scale effect (0.470) and the dividend effect (0.306). The average composite index increased from 0.184 to 0.425. ② The coupling coordination degree between intensive land use and new-type urbanization increased from 0.367 to 0.600, and the coupling coordination state showed a good evolution trend of “mild imbalance-near imbalance-low coupling coordination-major coupling coordination”. However, the development of each municipal unit was quite different. ③ According to the PVAR model results, there was a significant interaction between new-type urbanization and intensive land use. However, the influence of intensive land use level on new-type urbanization level was greater (47.11%) than that of new-type urbanization level on intensive land use level (35.05%). [Conclusion] Compared with new-type urbanization, the “resource-asset-capital” attribute of intensive land use belonged to the category of productivity. Compared with intensive land use, the “scale-agglomeration-dividend-wealth” effect of new-type urbanization belonged to the category of production relationship. There was an unequal interaction relationship between new-type urbanization and intensive land use.

Abstract:[Objective] The objectives of this study were to obtain a deep understanding of the research progress and future development trend regarding soil aggregates at home and abroad, identify the current issues of great interest with regard to soil aggregates, and provide a reference for researchers and decision makers in the field of soil aggregates. [Methods] Based on the Web of Science Citation Database, and with the help of VOSviewer, CiteSpace scientific atlas mapping software, and the BiblioShiny program analysis tool in the R language, a quantitative analysis was conducted on the number of publications, journals, countries (regions), institutions, keywords, and subject evolution of soil aggregate research. [Results] The number of papers published in the field of soil aggregates generally increased over time. In terms of national research strength, the top three countries were China, the United States, and Germany. The number of papers published by China far exceeded that of other countries, and accounted for 25.4% of all papers published relating to soil aggregates. Among the institutions conducting research on soil aggregates, the Chinese Academy of Sciences, the University of the Chinese Academy of Sciences, and the Northwest A&F University occupied the main positions. The main journals that published soil aggregate papers were Geoderma, Soil & Tillage Research, Catena, and Science of the Total Environment. The strategic coordinate map and keyword analysis showed that soil organic matter was the core subject of research in this field, and keywords such as “loess plateau”, “conservation agriculture”, “ecosystem services”, “soil health”, and “microbial community” were areas of intense research interest in this field in the past five years. [Conclusion] Under the background of climate change, research studies on soil aggregates, organic matter, and microbial biomass are on the frontier of soil aggregate research. Sustainable agricultural development, soil health, and interdisciplinary topics will become the focus of future research.

Abstract:[Objective] The temporal and spatial characteristics of the dominant transformation of cultivated land use in Henan Province was analyzed in order to provide a scientific basis for the rational and optimal allocation and sustainable utilization of cultivated land in the main intensive grain producing areas in the north. [Methods] We interpreted data from five Landsat TM images from 2000 to 2020 to construct contribution degree, range, and speed models of cultivated land use change. Temporal and spatial change characteristics of cultivated land quantity and spatial form were quantitatively described from the dominant perspective. Spatial visualization was carried out with the help of “3S” means. [Results] ① From 2000 to 2020, the quantity and form of cultivated land use transformation in Henan Province experienced a drastic transformation process. The net decrease in cultivated land was 5 609.93 km², a decrease of 22.78%. ② The change range of cultivated land use transformation in Henan Province was the greatest from 2015 to 2020. ③ The spatial form of cultivated land presented a distribution characteristic of outward diffusion with Zhengzhou City as the center. The greatest change in cultivated land use was observed in Central Henan Province, with the least change in Western Henan Province. Changes in Northern, Southern, and Eastern Henan Province were characterized as moderate. [Conclusion] The spatio-temporal characteristics of the explicit transformation of cultivated land use in Henan Province from 2000 to 2020 had obvious consistent differences. Greater attention must be given to the quantity of cultivated land use transformation and the range of cultivated land use transformation in the Central Henan Province.

Abstract:[Objective] The relationship between land use change and ecological process in the ten tributaries area in Inner Mongolia was studied to reveal the relationship between human activities, land use, and ecological environment in order to provide a basis for the optimization of land use structure and regional ecological environment protection. [Methods] Landsat images from 2000 to 2020 were selected. Land use data and transfer matrices in different periods were obtained by using the method of supervised classification combined with a land statistical module. The dynamic change of land use and the comprehensive index of land use degree were analyzed. On this basis, the NDVI value, ecological environment quality index, and other indicators were selected by using mathematical statistics and other methods to comprehensively evaluate the ecological environment quality of the ten tributaries. [Results] ① During the 20 years of the study period, the proportion of forest land and grassland area changed the most, and the proportion of water area was the smallest, with frequent transitions between land use types, An obvious “upward trend” for forest land and an obvious “downward trend” for grassland and unused land were observed; ② The ecological environment quality indexes of the transformation of land use types in 2000, 2010, and 2020 in the ten tributaries were 0.526 1, 0.537 3 and 0.543 3, showing an overall upward trend. In terms of spatial distribution, the ecological environment quality was high in the east and low in the west, and high in the south and low in the north; ③ The annual average precipitation and annual average wind speed had significant positive impacts on the ecological environment quality. The annual average temperature had a significant negative impact on the ecological environment quality. [Conclusion] With the rapid development of urbanization occurring from 2000 to 2020, the ecological environment quality of the ten tributaries has also developed in a good direction. The ecological environment quality in the study area has improved overall and deteriorated locally. The transformation between construction land, forest land, grassland, and unused land is the main reason for changes in ecological environment quality. Environmental protection policies such as returning farmland to forest have continuously improved the environmental quality of the study area.

Abstract:[Objective] The spatial change characteristics and spatial aggregation characteristics of important ecological protection areas in the Poyang Lake urban agglomeration were analyzed in order to provide a basis for delineating “three districts and three lines” and rational planning of territorial space, and to provide a theoretical reference for promoting the coordinated development between high-quality economic development and ecological protection in the Great Lake Basin. [Methods] The study area was the urban agglomeration around Poyang Lake. Land use data for 2000, 2010, and 2020 were used with the InVEST model, the revised universal soil loss equation (RUSLE), and a GIS spatial analysis method to select types of ecological services (such as water conservation, soil conservation, biodiversity conservation, water purification, soil erosion sensitivity, and water environment sensitivity) to identify the important areas of ecological protection in the study area, and to analyze their spatial variation characteristics. [Results] ① In 2000, 2010, and 2020, the areas of important ecological protection in the urban agglomeration around Poyang Lake were 6.34×10⁴, 6.35×10⁴, and 6.28×10⁴ km², respectively. The land use types were dominated by forest land and water areas, showing the distribution characteristics of “high on both sides and low in the middle”. ② At a grid scale of 2 km×2 km, the importance of ecological protection in the urban agglomeration around Poyang Lake was significantly clustered in space, and the high and high clustering areas were mainly located in the eastern and western mountainous areas with fewer anthropogenic activities and good ecological protection. Low and low agglomeration areas were mainly located in the plain area around the Poyang Lake (where human activities are intensive), and some functions and structures of the ecosystem itself were damaged during economic development. ③ From 2000 to 2020, the changing and stable areas of ecological protection importance were located in the Huaiyu mountain area and the Poyang Lake Plain, and the enhanced areas were located in Fuliang County, Wuyuan County, and the Poyang Lake District; and the weakened areas were located in Yichun City, Pingxiang City, and Yingtan City. [Conclusion] For extremely important and highly important areas, stabilizing forest coverage and improving forest quality is the first task. Secondly, measures should be taken to effectively promote wetland restoration and the construction of nature reserves in order to curb habitat degradation. For medium-important, moderately important, and less important areas, the relationship between high-quality economic development and ecological protection should be properly handled. Especially in areas with intensive human activities, urban green space coverage should be increased, and ecological buffer zones should be established around cities to alleviate the pressure of ecological space survival.

Abstract:[Objective] The coupling coordination of high-quality development with water resource protection and utilization in Guiyang City, Guizhou Province, were studied in order to provide a scientific basis for further promoting efficient water resource supply and ecological water environment maintenance in southwest karst mountainous areas, thereby promoting regional high-quality development as a whole. [Methods] The research and coordination level, spatial-temporal differentiation characteristics, and factors influencing high-quality development and water resource protection and utilization in Guiyang City from 2010 to 202 were analyzed by using comprehensive evaluation, coupling coordination degree, spatial autocorrelation, and geographic detector models. [Results] The level of high-quality development in Guiyang City has increased significantly over time, while the level of water resource conservation and utilization has fluctuated and decreased. The coupling coordination degree of high-quality development and water resource protection and utilization has shown an increasing trend, and has undergone an evolution process on the verge of malcoordination and barely coordinated areas. The overall spatial distribution pattern was higher in the central and western parts of the city, and lower in the eastern part. The coupling coordination degree had a significant positive spatial correlation, and the spatial correlation between high-high agglomeration and low-high agglomeration was obvious. The influencing factors were highly variable, and the two-factor enhancement effect and non-linear enhancement effect were obvious. [Conclusion] The interdependence between high-quality development and water resource protection and utilization in Guiyang City is increasing, Therefore, in the future, we should enhance the role of innovation as the first driving force, optimize the structure of water resource utilization, improve the capacity to manage “three rivers”, and promote regional coordination and high-quality development.

Abstract:[Objective] The ecological water requirement for restoring an area of damaged vegetation in an arid environment was analyzed in order to provide a scientific basis for determining the water resources required in different stages of ecological restoration and the optimal allocation of water resources. [Methods] Based on a series of Landsat images acquired in 1990, 2000, 2010, 2015, and 2020, the temporal and spatial evolution characteristics of vegetation water consumption and ecological restoration water demand in the plain area of Habahe County, Xinjiang Wei Autonomous Region were quantitatively analyzed by remote sensing technology combined with an improved Penman formula method. [Results] ① From 1990 to 2020, the average water consumption of natural vegetation was 7.55×10⁸ m³, and decreased at a rate of 3.60×10⁷ m³/5 yr. Correspondingly, the area of natural vegetation decreased at a rate of 17.36 km²/yr, and the vegetation coverage changed from high vegetation coverage to medium vegetation coverage, resulting in serious ecological damage. ② There were great differences in the spatial and temporal distributions of vegetation water consumption in the region: the spatially high values were mainly located in the Haba River basin, while the vegetation water consumption in the Bie River basin was generally low. Temporally, vegetation water consumption in 2000 was the highest, and vegetation water consumption in a given year was mainly concentrated in the middle growth period. ③ The ecological restoration water demand in an oasis area was 4.62×10⁸ m³ for maintaining the status quo (2020), 6.65×10⁸ m³ for restoring to the average ecological level from 1990 to 2020, and 9.55×10⁸ m³ for reaching the best ecological level from 1990 to 2020 (2000). [Conclusion] Under the dual actions of human activities and nature, the ecological environment of the irrigation area showed a degradation trend from 1990 to 2020, and the spatial distribution of ecological water consumption was unbalanced. The spatial and temporal allocation of water demand for ecological restoration of an area of damaged vegetation should be optimized and improved according to the spatial and temporal distribution of water consumption.

Abstract:[Objective] The state of the water ecological environment in the Yangtze River Economic Belt was evaluated in order to provide a scientific basis for the formulation of ecological protection policies in the region. [Methods] Based on the DCSM model and qualitative analysis, 22 water ecological environment indicators were selected which included the four subsystems of driving force, carrying source, state, and management. By using random forest dimensionality reduction, 12 highly correlated indicators were identified as a comprehensive evaluation system. The water ecological environment of 11 provinces in the Yangtze River Economic Belt was ranked from 2010 to 2019 by combining the weighted rank sum ratio model and the adversarial interpretative structure model. The ranking was determined according to the degree of superiority and inferiority. [Results] ① In general, the water ecological environment of the Yangtze River Economic Belt differed significantly among regions, showing an asymmetric U-shaped distribution with the downstream region being superior, the upstream region being second, and the midstream region being worst. ② In terms of spatial distribution, the water ecological status of Zhejiang Province ranked first, while that of Jiangsu, Yunnan, Guizhou, Anhui, Jiangxi, Sichuan Province, Chongqing City, and Hubei Province decreased in a “steplike” descending manner, and that of Hunan Province and Shanghai City ranked low. ③ In terms of classification indexes, industrial wastewater reuse rate, water consumption of 10 000 yuan of agricultural GDP, and wastewater discharge of 10 000 yuan of industrial value added had significant impacts on the water ecological environment. [Conclusion] The overall water ecological environment of the Yangtze River Economic Belt has still not reached a safe and stable state. Improving the quality of the water ecological environment from various aspects according to local conditions is an important driving force for promoting high-level sustainable development of the Yangtze River Economic Belt.

Abstract:[Objective] Previous studies regarding the use of the erosion-productivity impact calculator (EPIC) model from 1991 to 2021 were retrieved in order to conduct bibliometrics and cluster analysis so that the direction for the future application and development of the EPIC model could be determined. [Methods] The R-bibliometrix tool was used to analyze literature related to the EPIC model in the Web of Science Core Collection Database, and 261 papers were ultimately selected. The research hotspot and historical development trend of EPIC model were analyzed. [Results] During 1991—2021, the applications of the EPIC model were mainly focused on four aspects: water resources, crop growth, soil erosion and organic matter loss, and agricultural drought. The EPIC model had high simulation accuracy and was able to well evaluate water erosion, soil nutrient loss, and crop yield in the past, present, and future. However, disadvantages included too many parameters and extensive input data requirements. [Conclusion] The EPIC model has many modules and thus has potential to be applied across broadly different research fields in the future. It also has the potential to be coupled with other models and deep learning methods in the future in order to carry out in-depth simulations regarding “double carbon”, soil erosion, crop production, and climate change responses.

Abstract:[Objective] The method for building a society having robust and effective responses to natural disasters was determined in order to provide a scientific reference for preventing and reducing risks from major natural disasters in the red soil area of South China. [Methods] Changting County, Fujian Province was used as a typical disaster area in the red soil area of South China. An index system was constructed from three dimensions that included rigid resistance, elastic control, and resilient recovery. The entropy weight TOPSIS model and the coupling coordination model were used to quantitatively evaluate the comprehensive level and the coupling and coordination between the first level of rigid-elastic-resilient society responses to natural disasters in Changting County from 2006 to 2019. An obstacle factor analysis was conducted. [Results] ① The level of rigid-elastic-resilient society responses to natural disasters in Changting County evolved from a slow decline to a significant increase, with an increase of 0.4616 from 2006 to 2019, showing a significant growth trend overall. ② The rigid resistance level, elastic control level, and resilience recovery level of the rigid-elastic-resilient society responses to natural disasters in Changting County generally showed a significant growth trend. Only the resilience recovery index significantly decreased from 0.402 0 to 0.280 9 from 2006 to 2010. ③ Among various evaluation indicators, the decline of disaster monitoring capability, public security management level, proportion of tertiary industry, carbon storage capability, and water conservation function were the key factors restricting the development of the rigid-elastic-resilience society responses to natural disasters in Changting County. [Conclusion] The red soil area of South China was evaluated from three dimensions including rigid resistance, elastic control, and resilient recovery. These three dimensions effectively and accurately reflected the comprehensive level of rigid, elastic, and resilient society responses to natural disasters in the region. At the same time, the weak links in development should be strengthened to avoid the decline of rigid-elastic-resilient society responses to natural disasters.

Abstract:[Objective] The village type identification was carried out scientifically to provide technical support and a decision-making reference for the formulation of the overall territorial space planning and the implementation of the rural revitalization strategy for Xingguo County, Jiangxi Province, in order to provide experience reference for the village type identification in the hills and mountains in Southern China. [Methods] Villages were taken as the research units. A village layout suitability evaluation index system and a rural revitalization potential evaluation index system were constructed. The village types in Xingguo County were identified by combining the AHP and CRITIC methods to determine the index weight. A coupling coordination model was constructed. [Results] ① The overall village layout suitability in Xingguo County was in the general level, and the suitability grades were mainly in the middle suitability level, with significant differences in spatial distribution, showing the spatial characteristics of “decreasing in a stepwise manner from the central part of the city to the surrounding areas”. ② The overall level of rural revitalization potential needs to be improved. The high-level areas were mainly located in the villages surrounding the urban areas and the resident villages of each township. ③ The coupling degree between the suitability of village layout and rural revitalization was high. The coordination degree needs to be improved from the average coupling coordination degree, with the largest number of villages at the primary coupling coordination degree. ④ The types of villages in Xingguo County were identified as suburban integration villages, clustered development villages, survival and upgrading villages, characteristic protection villages, and relocated and evacuated villages. Corresponding development strategies were proposed for different types of villages. [Conclusion] Village layout was closely related to local topography and social and economic development. The potential of rural revitalization was positively correlated with the suitability of rural layout. Therefore, different development strategies should be proposed for different village types.

Abstract:[Objective] Green utilization efficiency of cultivated land in the lower Yellow River and its convergence and influencing factors were analyzed in order to provide a reference for ecological protection and high-quality development of cultivated land in the lower Yellow River. [Methods] Undesirable outputs such as surface pollution and carbon emissions from cultivated land, and the carbon sequestration and sink capacity of cultivated land resources were simultaneously incorporated into the evaluation index system. The green utilization efficiency, convergence, and influencing factors of cultivated land in 34 municipalities in the lower Yellow River from 2007 to 2020 were systematically analyzed using the EBM model, the convergence model, and the panel random effects Tobit model. [Results] ① The green utilization efficiency of cultivated land in the lower Yellow River showed an overall upward trend, but still did not reach the optimal state by the end of 2020. The green utilization efficiency of cultivated land in the lower Yellow River was spatially unbalanced. The green utilization efficiency of cultivated land in Southern He’nan and Northern Shandong provinces was high, while that in Zhengzhou, Weihai, and other cities was always low. ② From the perspective of efficiency decomposition, the main driving force for the improvement of green utilization efficiency of cultivated land in the lower Yellow River was scale efficiency, while the resistance came from pure technical efficiency. ③ From the convergence test, both σ convergence and β convergence existed in the green utilization efficiency of farmland in the lower Yellow River. The inter-city gap of cultivated land green utilization efficiency in He’nan Province was obviously lower than in Shandong Province, but the convergence rate in Shandong Province was faster. ④ In terms of influencing factors, crop planting structure and government financial support to agriculture increased green utilization efficiency of cultivated land in the lower Yellow River, while the urban-rural income gap, economic development level, and farmland machinery input intensity decreased green utilization efficiency. [Conclusion] In the future, the lower Yellow River should not only improve the comprehensive management level of the green utilization of cultivatedpland and strengthen inter-city exchanges and cooperation, but should also focus on the coordination between the convergence rate of green utilization efficiency of cultivated land and the development gap in each region while promoting development of the green utilization of cultivated land.

Abstract:[Objective] The land use carbon emission pattern was analyzed and the value of carbon compensation was estimated in the Three Gorges reservoir area in order to provide a reference for guiding low-carbon development and improving the carbon compensation mechanism in the basin. [Methods] We used the carbon emission factor, energy consumption per unit GDP, and economic contribution coefficient to calculate the carbon compensation value of land use. The net carbon emission was taken as the benchmark value. The carbon emission threshold and carbon emission intensity were revised. [Results] ① Carbon emission and carbon absorption in the Three Gorges reservoir area showed an overall upward trend from 1980 to 2021. Cultivated land and forest land were the main sources of carbon sequestration from regional land use, and urban and rural industrial, mining, and residential land were the main sources of carbon emissions from regional land use; ② The carbon absorption pattern was low in the west and high in the east. From 1980 to 2021, the districts and counties with middle-high level and high level carbon absorption increased significantly, and most of them were located in the east and north of the study area, while the counties with low level carbon absorption decreased; ③ In terms of carbon emission patterns, land use carbon emissions in the Three Gorges Reservoir area from 1980 to 1990 were at a low level or medium-low level. The overall carbon emissions of the reservoir area increased from 2000 to 2021, with the main urban area of Chongqing City in the west; Wanzhou, Kaizhou District, and Yunyang County in the middle; and Yiling District in the east at medium and high levels. Wulong County was at a medium level. The carbon emissions of Badong, Wushan, Wuxi, Zigui County, and other surrounding areas were at low and medium-low levels; ④ In the study area, nine districts and counties were ecological surplus areas and should obtain carbon offset funds. Fengjie County should receive the highest carbon compensation fund of 6.87×10⁵ yuan. Seventeen districts and counties were ecological deficit areas. Yubei District paid the highest amount of carbon offsets of 1.53×10⁷ yuan. [Conclusion] In the ecological deficit areas, regional cooperation should be promoted to control carbon emissions, and a horizontal carbon compensation mechanism should be established. The scale of construction land should be controlled, and land use allocation should be optimized. The concept of green development should be implemented to enhance carbon sequestration capacity. Energy supply structure should be optimized and energy utilization rate should be increased to guide low-carbon development of the watershed.

Abstract:[Objective] The effects of changes in aboveground litter, underground roots, and mycorrhizal inputs on soil microaggregates of restored red soil forestland were analyzed in order to provide a basis for soil function reconstruction and understanding the ecosystem carbon cycle after forest restoration of degraded lands. [Methods] The study was conducted in a pure Schima superba forest, a typical broad-leaved forest recovered from eroded and degraded red soil in a subtropical region. Five input treatments were established: no litter (CT), mycorrhiza (M), root+mycorrhiza (RM), aboveground+underground litter (LRM), and double aboveground+underground litter (DLRM). The composition of soil microaggregates, organic carbon, and their chemically bound forms were analyzed. [Results] There were no significant differences in soil microaggregate mass percentage, organic carbon, Ca-SOC, Fe (Al)-SOC, and Ca-SOC/SOC among the different treatments (p＞0.05). Compared with CT, LRM reduced Fe (Al)-SOC/SOC of microaggregates of size 20—50 μm and 50—200 μm by 40.06% and 46.67%, respectively (p＜0.05). Soil microaggregate mass percentage, organic carbon, Ca-SOC, and Fe (Al)-SOC decreased as particle size increased, and organic carbon and bound organic carbon tended to be enriched in smaller particle size groups (＜20 μm). The content of Ca-SOC in microaggregates (0.55—1.28 g/kg) was much lower than observed for Fe (Al)-SOC (6.88—13.34 g/kg), but its variation range in different particle sizes was greater than that of Fe (Al)-SOC. The percentage of Ca-SOC/SOC (1.54%—3.44%) was also less than the percentage of Fe (Al)-SOC/SOC (16.75%—42.54%). Microaggregate mass percentage, organic carbon, Ca-SOC, and Fe (Al)-SOC were positively correlated (r=0.497—0.757, p＜0.01). [Conclusion] Soil microaggregates and their organic carbon in a restored S. superba forest were affected by particle size. Both quantities responded to short-term inputs of aboveground litter, underground roots, and mycorrhiza, but did not reach a significant level, and therefore need to be studied over a longer time period.

Abstract:[Objective] The effects of forest types on soil carbon and nitrogen contents and enzyme activity were analyzed in order to provide a scientific basis for the selection of tree species and forest management methods in the transformation of subtropical coniferous forests. [Methods] The study evaluated data from a subtropical evergreen broad-leaved forest (Castanopsis carlesii forest), an evergreen deciduous broad-leaved mixed forest (Betula fujianensis and Phoebe bournei mixed forest), and a coniferous forest (Pinus massoniana forest) at the same altitude and similar environmental conditions. [Results] ① The total soil organic carbon content in the P. massoniana forest was significantly greater than in the other two forest types, and the total soil nitrogen content was not significantly different from that in the B. fujianensis and P. bournei mixed forest. However, both carbon and nitrogen contents were significantly greater than in the C. carlesii forest. The soil nitrogen and carbon reserves of the P. massoniana forest and the B. fujianensis and P. bournei mixed forest were significantly greater than the nitrogen and carbon reserves of the C. carlesii forest. The soil soluble organic carbon contents in the P. massoniana forest and the B. fujianensis and P. bournei mixed forest were significantly greater than in the C. carlesii forest. The soil soluble organic nitrogen content in the P. massoniana forest was significantly less than in the C. carlesii forest and the B. fujianensis and P. bournei mixed forest. The soil microbial biomass carbon and nitrogen contents in the C. carlesii forest and the P. massoniana forest were significantly greater than in the B. fujianensis and P. bournei mixed forest. There were no significant differences in the soil ammonium nitrogen contents among the three forest stands. However, the soil nitrate nitrogen content in the B. fujianensis and P. bournei mixed forest was significantly greater than in the other two forest types. ② The soil urease activity in the C. carlesii forest was significantly greater than in the B. fujianensis and P. bournei mixed forest. There were significant differences in soil invertase activities among the three stands, and the differences in activity followed the order of P. massoniana forest ＞ C. carlesii forest ＞ B. fujianensis and P. bournei mixed forest. The soil catalase activities in the P. massoniana forest and the C. carlesii forest were significantly greater than in the B. fujianensis and P. bournei mixed forest. There was no significant difference in soil phosphatase activity among the three forest stands. Soil β-glucosidase activity in the P. massoniana forest was significantly greater than in the C. carlesii forest and the B. fujianensis and P. bournei mixed forest. RDA analysis showed that the main factors affecting the change of soil enzyme activity in the three forests were total soil carbon (explanation rate of 59.5%), total nitrogen (explanation rate of 11.0%), and nitrate nitrogen (explanation rate of 14.6%). [Conclusion] The P. massoniana forest and the B. fujianensis and P. bournei mixed forest had greater soil carbon and nitrogen storage values than observed for the C. carlesii forest under the same disturbance background. The increased soil organic matter was conducive to increase soil enzyme activity.

Abstract:[Objective] The bacterial community microdiversity in the maize rhizosphere and bulk soil was determined to study the relationship between microdiversity and soil organic carbon mineralization through the use of high-resolution taxonomy in order to provide a theoretical foundation for microbially driven carbon cycling in the maize rhizosphere. [Methods] The rhizosphere and bulk soil samples were collected in maize fields on the experimental farm of Cao Xinzhuang, Northwest A&F University. High-throughput sequencing technology was used to detect the bacterial community structure in the rhizosphere and bulk soil. Thereafter, distinct taxonomic resolution levels (OTUs vs ASVs) were used to reveal the microdiversity of bacterial communities. Incubation experiments were conducted to examine organic carbon mineralization characteristics of the rhizosphere and bulk soil of maize. [Results] The distinct taxonomic resolution levels revealed similar bacterial community structure in the rhizosphere and bulk soil. ASVs depicted bacterial community composition at a fine scale taxonomic resolution level, and revealed different strains or ecotypes prevalent within the same OTU. Furthermore, differences in the relative abundance of bacterial species from distinct growth strategies (r-and K-strategies) were the main factors contributing to the different bacterial community structures in the rhizosphere and bulk soil. Incubation experiments showed that organic carbon mineralization was significantly higher in the rhizosphere than in bulk soil. The results of three years of continuous sampling revealed that roots were the main factor causing differences between the rhizosphere and bulk soil physicochemical properties of mature maize in the field, and that time had little influence (from 2019 to 2021). Cumulative mineralization of soil organic carbon was associated with bacterial microdiversity between the rhizosphere and bulk soil. [Conclusion] ASV-level exhibited significant differences in bacterial microdiversity between the rhizosphere and bulk soil in a maize field, and bacterial microdiversity was associated with cumulative mineralization of soil organic carbon.

Abstract:[Objective] The soil aggregate stability and differences in organic carbon distribution for Bayanbulak alpine grassland, Xinjiang Wei Autonomous Region under different land utilization methods were analyzed in order to provide a theoretical basis for the evaluation of soil aggregate organic carbon and other ecological functions in this region. [Methods] Three land utilization methods for an alpine grassland in Bayinbuluk were evaluated: reclamation, abandoning farming to grazing, and grazing. Soil aggregates were screened by dry screening and wet screening, mean weight diameter (MWD), geometric mean diameter (GMD), percentage of aggregate destruction (PDA), and soil organic carbon (SOC) contents of soil aggregates were measured and calculated to quantify differences in soil aggregate stability and organic carbon in an alpine grassland under different land utilization methods. [Results] ① Under the three land utilization methods, soil aggregates in an alpine grassland were primarily large aggregates (≥0.25 mm). In the subsurface (10—20 cm) soil, the PDA for the treatment of abandoning farming to grazing was significantly lower than that of the grazing treatment (p＜0.05), and was not significantly different from the PDA for the reclamation treatment (p＞0.05). In addition, the soil PDA values of the remaining soil layers in the treatment of abandoning farming to grazing were significantly greater than those observed for the reclamation treatment and the grazing treatment (p＜0.05). In the surface layer (0—10 cm), there was no significant difference in PDA between the reclamation treatment and the grazing treatment (p＞0.05). The PDA values of the other soil layers in the reclamation treatment were significantly greater than in the grazing treatment. ② The SOC content, soil aggregate organic carbon content, and the contribution rate of soil aggregates in the treatment of abandoning farming to grazing were significantly less than those in the other treatments (p＜0.05). In the 0—10 cm soil layer, organic carbon content and its contribution rate of aggregates with particle size greater than 5 mm in the grazing treatment were greater than those in the reclamation treatment (27.89 g/kg, 6.34%) and the treatment of abandoning farming to grazing (36.96 g/kg, 14.3%). In the subsurface layer (10—20 cm), lower layer (20—30 cm), and deep layer (30—40 cm), the organic carbon content and contribution rate of soil aggregates with a particle size of ≥5 mm in the treatment of abandoning farming to grazing were significantly less than those in the reclamation treatment and the grazing treatment (p＜0.05). ③ The mass percentage of soil aggregates and their stability were significantly correlated with SOC content (p＜0.05). The mass percentage of soil aggregates ≥2 mm, MWD and GMD of soil aggregates were significantly positively correlated with SOC content (p＜0.05), of which soil aggregates ≥5 mm showed a very significant positive correlation (p＜0.01) with SOC content. The mass percentage of soil aggregates less than 2 mm and the stability of soil aggregates were significantly negatively correlated with SOC content (p＜0.05), of which soil aggregates ＜1 mm were extremely significantly negatively correlated with SOC content (p＜0.01). [Conclusion] Grassland reclamation activities reduced the stability of soil aggregates and their SOC contents. Soil aggregate stability and SOC content were the lowest in the treatment of abandoning farming to grazing. It is recommended that grassland should be moderately restored (fertilized, sown, etc.) after abandonment for grazing and utilization.

Abstract:[Objective] The land use carbon emissions in Jiujiang City, Jiangxi Province were quantitatively measured, and its temporal and spatial evolution characteristics, and the risk of land use carbon emissions were determined in order to provide a scientific reference for the construction of green and low-carbon land use methods in Jiujiang City. [Methods] Land use carbon emissions, and their temporal and spatial variation characteristics in Jiujiang City from 2000 to 2020 were measured by the carbon emission coefficient method. The carbon emission risk of each county was identified by the carbon emission risk index based on grid perspective. The factors influencing land use carbon emissions were analyzed based on the logarithmic mean divisia index (LMDI) model. [Results] Net carbon emissions from land use in Jiujiang City have been increasing at an average annual rate of 13.75% during 2000—2020. Construction land was the main carbon source, accounting for more than 90% of the carbon emissions, whereas forest land was the main carbon sink. Additionally, net carbon emissions in Jiujiang City presented a spatial distribution pattern of “high in northeast and low in southwest”. Wuning County and Xiushui County have good forest coverage and have always been carbon sinks. Lianxi District, Xunyang District, Hukou County, and Ruichang City, with more construction land, had the largest net carbon emissions and accounted for more than 95% of carbon emissions in Jiujiang City. Moreover, the carbon emission risk from land use in Jiujiang City was generally low, and showed a distribution pattern of “high in northeast and low in southwest”. High carbon emission risk areas were Lianxi District, Xunyang District, and Chaisang District, all along the Yangtze River. Economic development level was the main factor increasing carbon emissions, while energy consumption intensity was the key factor curbing carbon emissions. [Conclusion] Carbon emissions from land use have increased significantly during 2000—2020. New carbon source land use should be controlled, land use structure should be optimized, a low-carbon, green-energy utilization system should be actively constructed, and “Jiujiang model” construction of green and low-carbon development should be promoted in the Yangtze River Economic Belt.

Abstract:[Objective] The basis of urban carbon carrying capacity was determined in order to provide scientific support for urban “double carbon” and low-carbon development. [Methods] Based on land use data for Yibin City, Sichuan Province in 2000, 2005, 2010, 2015, and 2020, habitat quality and carbon storage for Yibin City were measured by the InVEST model, an evaluation index system of carbon carrying capacity for Yibin City was constructed, and an in-depth study of the level of carbon carrying capacity for Yibin City was conducted. [Results] The carbon carrying capacity of Yibin City showed a change pattern of “first increasing, then decreasing, and then increasing”. The carbon carrying capacity scores for Yibin City in 2000, 2005, 2010, 2015, and 2020 were 0.525 4, 0.606 1, 0.506 4, 0.385 3, and 0.553 4， respectively. The degree of habitat degradation continued to deepen, and the habitat quality index showed a change pattern of “first increasing, then decreasing, and then increasing”. The carbon storage index continued to increase over time, and the carbon storage rate continued to decline. The complex system of carbon carrying capacity for Yibin City has gradually changed from an imbalanced state in 2000 to an intermediate coordination state in 2020. [Conclusion] The level of carbon carrying capacity in Yibin City is on the rise, but carbon storage and habitat quality in some areas are declining significantly.

Abstract:[Objective] The characteristics of surface soil soluble organic carbon (DOC), readily oxidized organic carbon (ROC), carbon pool stability, and carbon storage changes, as well as influencing factors of soil organic carbon (SOC) and DOC at different elevations in Tibetan Plateau were analyzed in order to provide a scientific basis for subsequent research on the stability of SOC in cold regions with complex terrain. [Methods] Data were collected from a rocky beach of the Sejila Mountain. One-way ANOVA was used to analyze soil physical properties and DOC, ROC, and SOC content characteristics at altitudes ranging from 4 300 m to 4 700 m. Pearson correlation analysis and redundancy analysis were used to determine the relationship between DOC, ROC, and influencing factors. [Results] ① Soil bulk density and dry density were negatively correlated with altitude, and their maximum values were 1.56 g/cm³ and 1.12 g/cm³, respectively. Soil water content and porosity were positively correlated with altitude, and the maximum values were 74.22% and 58.70%, respectively. ② SOC content initially increased with increasing altitude and then decreased. DOC and ROC showed fluctuating trends with elevation. ③ DOC/SOC and ROC/SOC reached maximum values at 4 400 m. The average DOC and SOC values were 40.779 kg/m² and 8.105 kg/m², respectively. The stability of the soil carbon pool in the rocky beach area was relatively good. ④ DOC had no correlation with soil physical properties, but was correlated with average SOC. ROC was correlated with physical properties, SOC, and its related factors. Each factor was correlated with changes in DOC and ROC in the rocky beach area of the Sejila Mountains. Explanatory contribution rate follow the order of average DOC＞soil porosity＞ROC/SOC＞soil water content＞SOC＞average SOC＞DOC/SOC＞soil dry density. [Conclusion] Soil DOC and ROC at different elevations were correlated, and average DOC, soil porosity, and ROC/SOC were important factors affecting the contents of DOC and ROC. There were close relationships among these factors.

Abstract:[Objective] The spatial-temporal evolution characteristics and driving mechanism of agricultural carbon emissions in Henan Province were determined to predict the change trend of agricultural carbon emissions during the next ten years in order to formulate an agricultural carbon sequestration and emission reduction scheme, and to promote the transformation to low-carbon and green agricultural production. [Methods] We used a carbon emission equity evaluation model, GeoDetector, and the GM (1,1) model to accomplish the study objectives. [Results] ① Agricultural net carbon emissions in Henan Province declined over time during the study period, with a distribution pattern of “high in the southwest and low in the northeast”. Carbon emissions from animal husbandry accounted for a large proportion of total emissions, and carbon emissions were mainly from cattle, sheep, and pigs. Wheat, corn and vegetables contributed more to carbon absorption than other sinks. ② The ecological carrying coefficient of agricultural carbon emissions was higher in the north and south, and lower in the west. The coefficient of economic contribution was high in the southeast and low in the southwest. ③ The agricultural employee population, per capita disposable income of rural residents, agricultural machinery gross power, and fiscal expenditures on education were the key factors affecting spatial differences in agricultural carbon emissions, and interactions among these factors were strong. ④ Agricultural net carbon emissions in Henan Province will continue to decrease from 2021 to 2030. It is estimated that Henan Province will achieve the goal of agricultural carbon neutrality by 2029. [Conclusion] In the future, Henan Province should strengthen science popularization, actively promote low-carbon agricultural production technology, and increase the efficiency of comprehensive utilization of agricultural resources. Additionally, all localities should give increased attention to system integration, strengthening regional cooperation, and achieving regional integration of agricultural carbon emission reduction.

Abstract:[Objective] Changes in land use and carbon stocks under different scenarios were evaluated to provide a scientific basis for optimizing ecological services and sustainable development. [Methods] Changes in land use and carbon storage under different scenarios were simulated and extrapolated by comprehensively using the PLUS and InVEST models. [Results] ① Similar land use changes were observed for both the natural evolution and ecological protection scenarios. Areas of farmland, grassland, and water decreased over time. There was a rapid expansion of construction land. The rate of construction land expansion was much higher for the natural evolution scenario (27.70%). Under the farmland protection scenario, changes in land use were different from those in the other two scenarios because of a decrease in woodland area and a rapid expansion in construction land area. ② Carbon storage in Kunming City decreased over time, with 3.37×10⁸ t in 2000, 3.34×10⁸ t in 2010, and 3.28×10⁸ t in 2020. By 2030. The carbon storage under the farmland protection and ecological protection scenarios will be relatively more than that under the natural evolution scenario. Adopting protective measures can effectively control the reduction in carbon storage; ③ The decrease in carbon storage caused by land use changes was 9.15×10⁶ t, and there was high consistency between land use changes and carbon storage changes. [Conclusion] Implementing a policy of farmland and ecological protection, limiting the expansion of construction land from, farmland and woodland, and optimizing land use structure will slow the loss of regional carbon storage.

Abstract:[Objective] The ecological and environmental effects of land use transition and their development trends were analyzed in order to provide a basis for promoting land use transition, low-carbon cycle development, and realizing the goal of “double carbon”. [Methods] We used land use data for Zunyi City of Guizhou Province in 2005, 2010, 2015, and 2020 and spatial analysis technology for this study. [Results] ① Land transformation from 2005 to 2020 was mainly manifested by the interconversion between carbon sink sites and the transformation of carbon sink sites to carbon source sites. ② Net carbon emission increased from 5.99×10⁵ tons in 2005 to 9.87×10⁶ tons in 2020, an increase of 9.27×10⁶ tons (1 548.15%). However, the incremental amount gradually decreased, and the rate of increase gradually decreased. ③ The value of ecosystem services in Zunyi City increased from 7.64×10¹⁰ yuan in 2005 to 7.73×10¹⁰ yuan in 2020, showing a fluctuating upward trend, with a total increase of 9.14×10⁸ yuan and a growth rate of 1.2%. ④ The gray prediction model showed that the net carbon emissions and ecosystem service value for Zunyi City will continue to increase in the future, with both showing a consistent upward trend. [Conclusion] Zunyi City continues to facing considerable pressure in terms of the ecological environment, and needs to increase efforts to enhance the value of ecosystem services while striving to achieve the goal of carbon peaking.

Abstract:[Objective] The effect of carbon storage under the transition of the productional-living-ecological space was systematically analyzed in order to optimize the spatial layout and increase the carbon sequestration capacity of the Guangxi border area ecosystem so that the strategic goal of “carbon neutrality” could be achieved in China. [Methods] This study used a land change dynamic attitude model and land use transfer matrix to describe the spatial distribution pattern and transformation characteristics of the productional-living-ecologyical space along the Guangxi border. Based on the InVEST model and the contribution rate of productional-living-ecologyical space carbon storage, the spatio-temporal variation of carbon storage and the impact of the productional-living-ecologyical space transition on carbon storage in the border area during 1990—2020 were determined. [Results] ① From 1990 to 2020, the border area was dominated by green ecological space, supplemented by agricultural production space and water ecological space, with a distribution pattern of “high in the north and south regions, and low in the central region”. ② During the study period, the transition of the productional-living-ecological space in the border area showed a stable development in the early stage, fluctuating development in the middle stage, and drastic development in the late stage. Except for the ecological space of the water area, the change of dynamic attitude in other areas was most significant from 2010 to 2020. ③ From 1990 to 2020, overall carbon storage in the border area showed a continuous decline over time, with a small change in the early and middle stages, and a profound change in the late stage. In the past 40 years, a total of 4.13×10⁶ t of carbon storage has been lost. The conversion of green ecological space and agricultural production space dominated the change of carbon storage in the Guangxi border area. [Conclusion] It will be necessary to adjust and optimize the land use structure of regional productional-ecological space, promote the integration of productioal-ecological space, and strengthen the regulation of space use with the goal of “carbon neutrality” so as to accurately guarantee improvement of regional carbon storage resources.

Abstract:[Objective] The suitable targets for soil and water loss prevention and control in different provinces and all of China were determined in order to help people of all sectors of society in understanding and applying the concept of soil and water conservation rate (SWCR) and related research, thereby providing a useful reference for facilitating the high quality development of soil and water conservation in the new age. [Methods] Based on the concept and related research results of SWCR as first presented by the Ministry of Water Resources in 2019, the concept of SWCR was expounded and the threshold of SWCR was determined. A grid of 30 m resolution was used as the spatial unit, and the multi-source geospatial data (including classification and grading of soil erosion, land use, topography, vegetation cover, etc.) were used to calculate and analyze the thresholds of SWCR in China and different provinces, and to explain the application of serial targets for SWCR in the liability assessment and implementation of targets for soil and water conservation in China. [Results] The core connotation of concept for SWCR represents the appropriate degree of soil erosion control that conforms to the natural law and meets the requirements of economic and social development. In the future, SWCR will become the multi-dimensional threshold system that includes reducting area and downgrading intensity of soil and water loss, and enhancing function of soil and water conservation. It could be used to comprehensively evaluate the current situation of regional soil and water loss control, and their appropriate degree could be achieved. At present, SWCR mainly reflects the appropriate goal of reducing the area of soil and water loss, which has been employed in the assessment of “Beautiful China Construction”, and which has become the core indicator in Opinions on Strengthening Soil and Water Conservation in the New Age that was printed and distributed by the General Office of the CPC Central Committee and the General Office of the State Council. [Conclusion] Based on the social ecosystem paradigm, it is suggested to study the threshold value and assessment methods of the change of soil and water loss in different regions at different levels based on comprehensive consideration of the influence of natural and social factors, the synergy of different local and spillover effects, and the balance of multiple objectives at ecological and economic levels. At the same time, focusing on the relevant requirements of the comprehensive management of the basin system, we should pay attention to the appropriate scale and reasonable layout of the main control measures or key objects, such as terraces, forest and grass, silting dam, slope cropland erosion gullies, etc.

Abstract:[Objective] Measures of national key soil and water conservation projects (NKSWCP) were systematically evaluated to provide a basis for improving the quality and efficiency of soil and water loss control in the black soil area of Northeast China, and to promote the high quality development of black soil protection and soil and water conservation. [Methods] The NKSWCP implemented in the black soil region of Northeast China before 2019 was taken as the object, and the slope treatment projects in 52 small watersheds and gully treatment projects in eight project areas were investigated, for which 325 slope map spots and 32 gullies were sampled, respectively. Results were analyzed and diagnosed. [Results] The preservation of gully treatment measures was significantly better than the preservation of slope treatment measures, and the average preservation rates were 95.00% and 56.51%, respectively. There were obvious category differences and spatial differences in the preservation rate of slope treatment measures, while gully treatment measures were generally well preserved, and the preservation rate of ecological land-saving measures was high. A few measures regarding slope and gully treatments are needed to improve construction quality and to strengthen future management in some areas. [Conclusion] In the future, in black soil region of Northeastern China, people should strengthen the optimization and management of traditional measures such as terraces, ridge tillage, and ridge plant belts; develop new ecological land-saving erosion control measures suitable for modern agriculture; and explore the construction of pilot bases for black soil land and water conservation technology. Regular evaluation of the effectiveness of NKSWCP should be conducted, a recommended directory of zoning and classification measures should be put forward, and different types of demonstration samples should be created.

Abstract:[Objective] The decoupling effect between cultivated land ecological destruction and agricultural economic growth in China were analyzed in order to provide scientific basis for understanding the coordinated development of cultivated land ecology and agricultural economy in China. [Methods] Using survey data from 31 provinces in China from 2011 to 2020, the entropy weight method and the TOPSIS method were used to evaluate and analyze the ecological damage degree of cultivated land for each province. The Tapio decoupling model was introduced to study the decoupling effect of ecological destruction of cultivated land and agricultural economic growth in China. [Results] In the early days, the growth of the agricultural economy in China’s provinces mostly came at the expense of the ecological health of cultivated land. There were certain differences between the ecological destruction of cultivated land and the growth of the agricultural economy between different regions. Shanghai, Zhejiang, Tibet, Chongqing, Fujian, and other regions had a high correlation between the ecological destruction of cultivated land and agricultural economic growth and development, among which Shanghai was always in an ideal state of strong decoupling, while Tibet, Chongqing, Fujian, and Zhejiang were in a state of decoupling without a negative decoupling effect. Overall, the correlation between cultivated land destruction and agricultural economic growth in most provinces had gradually increased over time, but the problem of non-coordination in some areas had been more prominent. It is, therefore, necessary to rectify this situation as soon as possible for provinces such as Qinghai, Hunan and Xinjiang (having five periods of negative decoupling), and Yunnan, Henan and Gansu (having three periods of negative decoupling). [Conclusion] It will be necessary to further promote the coordinated development of cultivated land ecology and the agricultural economy by firmly adhering to the ecological redline of cultivated land, and to firmly and effectively promote the development of cultivated land protection.