Abstract:[Objective] The effects of breccias and round gravels on steep cut slope infiltration, runoff, sediment yield, and hydrodynamic characteristics were analyzed in order to provide a theoretical basis for a soil erosion prediction model and soil conservation on a steep cut slope on the Qinghai-Tibet Plateau.[Methods] Based on the shape and material composition of a steep cut slope and on climatic characteristics along the Pai-Mo road, the cut slope runoff and sediment yield process was observed by using indoor simulated rainfall experiments. The experimental conditions were 50° slope, 120 mm/h rainfall intensity, different gravel contents (30%, 40%, 50%), and different gravel roundness (pebble, breccia).[Results] The average infiltration rate for the pebble slope was higher than for the breccia slope. The average runoff rate for the pebble slope was lower than for the breccia slope. The initial runoff time for the pebble slope was significantly later than for the breccia slope. The water flow state and pattern for both slopes were laminar and jet, respectively. Although the runoff shear force and Reynolds number for the pebble slope was slightly smaller than for the breccia slope, the Froude number and the average flow velocity for the pebble slope were larger than for the breccia slope. Therefore, the ability of runoff to carry sediment was greater for the pebble slope. The sediment yield rate for the pebble slope was double the rate observed for the breccia slope, and the total sediment yield for the pebble slope was about 20% higher than for the breccia slope.[Conclusion] Because pebbles do not fit closely together in the soil, they are more likely to cause turbulence under heavy rainfall, causing small annular rills to form centered on the pebbles scattered all over the pebble slope. The rill density and total sediment yield will be greater for a steep cut slope underlain by alluvial deposits than for a steep cut slope underlain by colluvial deposits.

Abstract:[Objective] The tensile strength characteristics of plant roots were studied to understand the performance of roots in complexes, in order to provide a basis for the selection of plants to be used in ecological slope protection.[Methods] Single root tensile tests were carried out on the roots of Iris tectorummaxim and Artemisia argyi taken from the source areas of the Lanniqing Landslide in Zhaotong City, Yunnan Province. The deformation and failure characteristics and tensile strength features were determined from macroscopic failure characteristics, deformation-tension curve, and feature parameters of fracture tension, maximum tension force, tensile strength, elongation rate, and tensile modulus.[Results] ① Iris root damage showed obvious ductility, while A. argyi root damage showed brittleness. The average elongation rate of I. tectorummaxim was about three times of A. argyi when damaged, and the root system of I. tectorummaxim showed good elastic-plastic deformation characteristics and strong deformation ability in the tensile process. ② Due to the protective effect of the periderm, the deformation-tension curves of Iris tectorummaxim roots mostly showed fluctuation and multiple peak values, while the roots of A. argyi mainly showed an approximately linear response. ③ Diameter and length significantly affected the mechanical features and parameters of roots. Fracture tension and maximum tension force increased with increasing root diameter, while tensile strength and tensile modulus decreased. The variation of the characteristic parameters of tensile strength was enhanced when the root length was short. Therefore, it is recommended that plants be selected that have little change in root diameter along the axial direction and the roots be as long as possible when carrying out relevant mechanical tests.[Conclusion] We recommend selecting vegetation with good root tissue structure, thick periderm tissue, strong deformation ability, large elongation rate, and obvious ductile failure characteristics to be used as slope protection plants.

Abstract:[Objectives] The windbreak efficiency of shelterbelts with different permeability on strip fields at the edge of the oasis in the Taklamakan Desert was analyzed in order to provide theoretical guidance for sustainable development of local grid strip fields.[Methods] The peri-urban shelter forest in the Qiaqikumu area of Yecheng County, Xingjiang Wei Autonomous Region on the southern edge of the Taklamakan Desert was selected as the research location. Field observations were made to quantify the windbreak effect for shelterbelts with different structures on the edge of the Taklamakan Desert oasis.[Results] ① The strip field within 10-15 m of the leeward side of the shelterbelts in the Qiaqikumu area of Yecheng County experienced the best windbreak effect. Crops with poor ability to withstand wind damage can be planted in this strip field. ② In general, the windbreak effect provided by shelterbelts was highest for plants with a height of 1.5 m and lowest for plants with a height of 2 m. Therefore, planting crops with a plant height of less than 1.5 m in the shelterbelts can effectively minimize losses caused by wind damage in this study area. ③ The sand fixation efficiency of the open-structure shelterbelt was the greatest, followed by the ventilated-structure shelterbelt. The sand fixation efficiency of the compact-structure shelterbelt was the worst. The order of sand fixation efficiency for the three kinds of structural shelterbelts followed the order of 58.39%>57.99%>36.29%, respectively.[Conclusion] In order to increase the sand-fixation efficiency of shelterbelts, open-structure shelterbelts should be recommended. This shelterbelt type can achieve the best windbreak effect. Strip fields around open-structure shelterbelts can be planted with crops having weak sand resistance.

Abstract:[Objective] The influence of biochar additions on water storage and water retention capacity of loessial soil during the rainy season was clarified in order to provide basic theoretical support for the scientific use of biochar and to improve soil on the Loess Plateau and determine the reasonable amount of biochar application.[Method] A multi-layer integrated soil moisture-temperature measurement system (JDTS-01) was used to make fixed point observations of soil moisture in a Loess Plateau field. The measured data were corrected by the field correction method. The dynamic change, recharge, and regression of water in the 0-40 cm soil layer were studied. Bivariate correlation analysis was conducted to determine the influencing factors and the relative importance of soil water recharge and regression under different levels of biochar addition.[Results] ① Low biochar content increased deep soil moisture, while high biochar content increased surface soil moisture. On the whole, biochar additions increased soil moisture content. A biochar content of 2.5% may be the inflection point affecting soil water infiltration and evaporation. ② After the addition of biochar, the water content in 0-20 cm soil layer increased, and the water content in 20-40 cm soil layer decreased. The water addition occurring due to rainfall could largely remain in the soil surface layer, and this effect on surface soil water content was greater when the biochar addition was larger. Water in the 0-20 cm soil layer with biochar dissipated faster, while the water in the soil without biochar penetrated deeper into the soil layer. ③ The addition of biochar can promote soil water recharge and weaken soil water regression, thereby increasing loessial soil water storage after rainfall.[Conclusion] Biochar additions can improve loessial soil water infiltration characteristics, reduce deep infiltration of soil water, and increase soil water storage in the topsoil on the Loess Plateau. These effects of biochar additions were more significant when the addition levels were greater than 4%.

Abstract:[Objective] The effect of different vegetation covers on soil infiltration capacity in Inner Mongolia was analyzed in order to provide a theoretical basis for ecological restoration and vegetation allocation of the region.[Methods] Three ages of abandoned grassland (13 years, 25 years, and 30 years) and 13 years of sea buckthorn land in this region were used as treatments. The disc infiltration method and soil water characteristic curves were used to compare differences in soil hydraulic conductivity, soil macroporosity, and macropore connectivity.[Results] ① Soil infiltration capacity was positively correlated with the length of abandoned years, and became stronger as the number of abandoned years increased. The stable infiltration rate of soil followed the order of 30-year abandoned grassland > 25-year abandoned grassland > 13-year abandoned grassland > 13-year sea buckthorn land. ② Macroporosity and macropore connectivity followed the order of 30-year abandoned grassland > 25-year abandoned grassland > 13-year abandoned grassland > 13-year sea buckthorn land. Soil macropores accounted for 0.0004%-0.0034% of the soil volume and accounted for 44.35%-86.92% of the soil saturated infiltration rate. ③ The content of water stable aggregates >0.25 mm was the main factor affecting soil infiltration rate.[Conclusion] Abandonment improved the infiltration capacity of grassland, and the infiltration capacity increased with increasing number of years of abandonment. The infiltration capacity of abandoned grassland was greater than that of sea buckthorn land having the same number of years of abandonment. The main influencing factors were the number and connectivity of soil macropores, and water stable aggregates >0.25 mm.

Abstract:[Objective] The distribution status and availability of soil selenium in three jujube orchards in Minqin County, Gansu Province was analyzed in order to provide a theoretical basis for the development of the selenium-enriched jujube industry.[Methods] The contents of total selenium and various forms of selenium in the 0-60 cm soil layer in three jujube orchards of Minqin County were measured by a method of successive extraction. Jujube distribution characteristics and availability were determined.[Results] ① The total selenium content was 24-520 μg/kg (average was 210.625 μg/kg), suggesting that total soil selenium was not deficient. ② Total soil selenium content increasingly declined with increasing soil depth in the 0-60 cm soil layer, with values in the three orchards following the order of Liugou>Zhangba>Xinguoyuan. According to the partition criterion for soil selenium content, the surface soil (0-20 cm) was categorized as selenium-rich; the subsurface soil (20-40 cm) was selenium-rich and selenium-poor; and the bottom soil layer (40-60 cm) was selenium-rich, selenium-poor, and selenium-deficient. ③ The available selenium content was 42.5 μg/kg and accounted for 20.2% of total selenium. Soluble selenium was 1.1-1.4 μg/kg, exchangeable selenium was 1.4-2.8 μg/kg. Both of these selenium forms together accounted for only 7.7% of the available selenium. The remaining available selenium was all organic selenium. ④ The available soil selenium increased with increasing number of reclamation years and followed the order of Xinguoyuan>Liugou>Zhangba among the three orchards. ⑤ The contents of total selenium, available selenium, and ineffective selenium were greater under trees than between tree rows.[Conclusion] Total selenium was not deficient in the soil of jujube orchards of Minqin County, but available selenium was deficient. Hence, development of the selenium-enriched jujube industry will require artificially supplementing soils with selenium fertilizer.

Abstract:[Objective] The changes in surface charge properties of soil particles and the net force between particles were analyzed, in order to elucidate the influence mechanism of particle interaction on pore conditions.[Methods] Soil pore conditions under different valence ion conditions were measured and the differences in soil pore characteristics formed by them were analyzed using industrial CT scanning techniques.[Results] ① The number of soil pores under the Mg²⁺ system was much larger (1.43 times) than the number of soil pores under the Na⁺ system. The number of soil pores (>1 mm) accounted for 1.43% and 1.06% of the total number of pores for the two respective systems. ② The pore volume of the soil pores (>1 mm) accounted for 50.4% and 40.2% of the total pore volume of the two respective systems. Additionally, the volume of the soil pores (>1 mm) for the Mg²⁺ system was 1.42 times higher than for the Na⁺ system. Soil porosity in the soils of the Na⁺ and Mg²⁺ systems was 2.06% and 2.35%, respectively. ③ As the concentrations of Na⁺ and Mg²⁺ increased, the surface potential of purple soil decreased from -391.7 mV to -96.7 mV and from -167.3 mV to -67.0 mV, respectively. At the same concentration, the surface potential (absolute value) of purple soil showed that Na⁺ exhibited greater performance than Mg²⁺. ④ The net force between soil particles decreased with increasing Na⁺ and Mg²⁺ concentrations. At the same concentration, the electrostatic repulsion between purple soil particles in the Mg²⁺ system was smaller than in the Na⁺ system. The critical concentration values of the net gravitational force exhibited between purple soil colloidal particles in the Na⁺ and Mg²⁺ systems were 0.1 mol/L and 0.005 mol/L, respectively.[Conclusion] Na⁺ and Mg²⁺ changed the pore condition of the soil by changing the surface charge properties of purple soil particles, which in turn caused changes in the interaction forces between soil particles, ultimately affecting the pore condition of the soil.

Abstract:[Objective] The effects of winter irrigation on soil water-heat-salt migration and crop growth during the freezing-thawing period were analyzed in order to provide a scientific basis for controlling soil salinization, and to ensure food security.[Methods] Statistical analysis and visualization methods were used to compare and analyze soil water-heat-salt migration and crop growth in winter irrigation and non-winter irrigation areas based on meteorological, soil physicochemical indicators, and crop growth data in an experimental field in the Qingtongxia Irrigation District of Ningxia from 25 October 2018 to 3 October 2020.[Results] Soil temperature changes in the Qingtongxia Irrigation District lagged behind air temperature changes, and the shallow surface soil temperature was more significantly affected by air temperature changes. The soil gradually froze from the surface downward and the freezing depth deepened as the temperature decreased. The frozen layer of soil thawed simultaneously from the soil surface and the bottom of the measurement profile during the thawing period. The entire soil freezing and thawing period lasted for 98 days. The soil moisture content increased significantly after irrigation. During the freezing period, irrigation decreased the temperature of each soil layer by 0.1-1.1℃. The variation trends of soil temperature and moisture in different soil layers during the winter irrigation period were basically the same as those during the non-winter irrigation period. After winter irrigation, the salinity of each soil layer decreased, especially in the 0-30 cm soil layer, and salinity decreased significantly. However, after the freezing-thawing period, salt accumulated in the soil. Winter wheat grew taller and corn grew faster in the winter irrigation farmland than in the non-winter irrigation farmland. Average wheat and corn yields increased by 20.64% and 4.20%, respectively, in the winter irrigation farmland.[Conclusion] Winter irrigation affected the distribution of soil water, heat, and salt, and effectively reduced soil salinity, resulting in increased crop growth and yield (especially wheat yield) in the Qingtongxia Irrigation District.

Abstract:[Objective] The landscapes and ecological service functions were comprehensively evaluated in order to provide scientific guidance for the selection of urban greening shrub species.[Methods] Several indexes including landscape service functions (such as greenness quantity, leaf greening period, aesthetic degree) and ecological service functions (such as water conservation, dust retention, oxygen generation while carbon fixation, cooling while humidifying, noise reduction) were investigated and measured, and a comprehensive evaluation model was built by using principal component analysis (PCA) to evaluate 26 common urban greening shrub species in the Guanzhong region of Shaanxi Province.[Results] ① According to the ranking results of the comprehensive evaluation of landscape service functions, Ligustrum quihoui, Viburnum odoratissinum, Photinia fraseri, Chaenomeles speciosa, Buxus megistophylla, Pittosporum tobira, and Buxus bodinieri received the highest grades of comprehensive evaluation (0.63-1.96) and proved to be the preferred shrub species in landscape beautification. ② According to the ranking results of the comprehensive evaluation of ecological service functions, L. quihoui, V. odoratissinum, C. speciosa, P. fraseri, P. tobira and Pyracantha fortuneana received the highest grades of evaluation (0.70-3.04) and performed outstanding in ecological improvement. ③ According to the comprehensive evaluation of landscape services combined with ecological services, the shrubs that received higher grades were L. quihoui (3.54), V. odoratissinum (2.86), C. speciosa (2.05), P. fraseri (1.72), and P. tobira (1.38).[Conclusion] Shrub species with higher grades should be selected preferentially according to different needs, thous can provide a basis for the selection and cultivation of greening shrub species in urban ecological gardens.

Abstract:[Objective] The soil salinization characteristics under different land use types in extremely arid regions were analyzed in order to provide support for the sustainable efficient utilization of regional land resources.[Methods] We used GPS positioning technology to investigate and sample the irrigation water, irrigation drainage, and soil under four typical land use types in the area of Lower Tarm River in different seasons. We combined those data with indoor measurement results to determine the variation characteristics of salinity and salt ions in the irrigation area.[Results] The soil in the study area was alkaline, and the salt type was mainly sulfate-chloride. The salt content was between 2.44 and 118.05 g/kg, and the pH value was between 8.05 and 8.34. The overall changes of soil salt content and pH value under different land use types in each season followed the order of salt wasteland > saline-alkali grassland > cultivated land and forest land. Analysis of samples from different soil depths indicated surface accumulation of salinity in June and October, and no obvious pattern in March and December. There was an obvious surface accumulation of salt in salt wasteland and saline-alkali grassland in different seasons at different soil depths. Forest land had no obvious salt accumulation pattern in each season. Because of the geographical location of the reservoir, the groundwater level in the study area was shallow (1.4-3.51 m), the groundwater salinity was high (1.56-21.30 g/L), and the salt ions in irrigation water and groundwater were mainly Na⁺ and Cl^-.[Conclusion] The soil salinization characteristics under different land use types in the study area were mainly affected by factors such as surface coverage, crop types, and irrigation events. The quality of groundwater and irrigation water was an important factor affecting the soil salt content and salt ion type in the study area. Certain measures should be taken to control the groundwater level and salt content so as to protect existing cultivated land and forest land. The irrigation and drainage water of high salt content from farmland should be discharged to the salt wasteland. In the future, relevant research should be conducted on the spatial configuration of agricultural land and salt wasteland, and the rational allocation of salt discharge land would be conducive to the desalination of farmland.

Abstract:[Objective] The specific effects of negative head irrigation system on tomato growth, irrigation method, and water utilization efficiency were studied in order to provide scientific references for improving the technical system of negative head irrigation and for improving the efficient utilization of water resources.[Methods] A pot experiment was conducted to study the effects of water supply location on tomato growth, water requirement, yield, and water use efficiency by using negative pressure irrigation technology.[Results] The location of the negative pressure water supply location had a significant effect on the growth and water use efficiency of tomato. The yields of plants irrigated with a single water-supplying disc buried vertically on one side of the root system and with a single water-supplying disc buried horizontally at the bottom of the root system were 14.3% and 0.5%, respectively, lower than the yield per plant irrigated with a water-supplying disc buried on each side of the root system and alternately supplying water. The growth and dry weight trends of above ground parts of tomato plants with alternate water supply on both sides of the root system were relatively small, but the root-shoot ratio was 33.3% greater than observed with the other two water supply locations. Moreover, the total water requirement of per plant for tomato plants irrigated with the alternate water supply on both sides of the root system was 24.7% and 17.4%, respectively, lower than with the other two water supply locations, and water use efficiency of single plant was 43.8% and 14.8% greater, respectively. Roots tended to grow more at the water supply source.[Conclusion] Different negative water head buried irrigation water source locations significantly affected tomato growth parameters. In terms of effective utilization of water resources, promotion of tomato plant growth, and increase of tomato yield, the optimal treatment was the system of disks buried on both sides of the root system and supplying water alternately. This system can effectively reduce irrigation water amount and improve water utilization rate, and should be promoted as an effective production practice.

Abstract:[目的] 分析不同扰动方式对内蒙古典型草原区土壤理化性质及植被特征的影响，为探索路域生态环境恢复规律，采用合理的恢复措施提供科学依据。[方法] 以锡林郭勒草原区3条公路(G303锡市—阿巴嘎旗段、G207锡市—西乌珠穆沁旗段、G207锡市—乌日图塔拉苏木段)为研究对象，采用空间代替时间的方法，调查研究了不同恢复年限(1，5，15 a)与不同扰动方式(碾压、路堑、取土场、路堤)路域土壤和植被特征。[结果] ①扰动方式对土壤理化性质有显著影响，其中土壤容重表现为：碾压＞路堤＞路堑＞取土场。随恢复年限增加，土壤容重表现为向未扰动区容重靠近趋势。土壤含水率表现为：碾压＜路堑＜取土场＜路堤，总体呈随恢复年限延长而增大趋势。土壤有机碳、全磷和全钾含量皆表现出碾压样地最差，路堤样地最优。②植物群落丰富度指数随恢复年限的增加显先增高后降低最终趋于稳定趋势，其中恢复5 a物种多样性指数相比于恢复15 a高。③主成分分析得出，恢复15 a的路堤、路堑、取土场扰动综合排名较高，其综合得分分别达到了2.33，1.42，1.32，碾压扰动的综合得分均处在最低水平，得分相比于未扰动区有明显差距，说明对生态系统破坏较为严重。[结论] 受到扰动的土壤理化性质及植被指数与未扰动土壤对比有很大差异，填方的土壤养分含量较高，而挖方土壤与未扰动区域相比，养分含量有明显缺失，需加强对该扰动区域的生态保护力度。

Abstract:[Objective] The temporal and spatial variation of ecological environmental quality and its heterogeneity were analyzed in order to provide a scientific basis for the government and relevant departments to formulate ecological environmental protection policies.[Methods] The google earth engine (GEE) platform was used to select Landsat images of central Yunnan Province from 2000 to 2020, and the remote sensing ecological index (RSEI) was extracted year by year. Spatial analysis methods such as hotspot analysis, standard deviation ellipse, and ecological environment gravity center shift were used to explore the temporal and spatial evolution of ecological environmental quality.[Results] ① The overall ecological environmental quality of the central Yunnan urban agglomeration showed a declining trend, and the average RSEI dropped from 0.51 in 2000 to 0.46 in 2020. ② The ecological environmental quality in Central and Eastern Yunnan Province was obviously better than in the western region, except for a few years. Most of the areas with better ecological environmental quality had greater forest coverage. ③ In the past 20 years, the spatial distribution of the ecological environment of the Central Yunnan urban agglomeration showed a north-south direction, and the overall ecological environmental quality of the urban agglomeration showed a certain degree of aggregation.[Conclusion] The deterioration of the ecological environment of the Central Yunnan urban agglomeration was closely related to the rapid expansion of the built-up areas of the urban agglomeration, climatic anomalies, vegetation destruction, and aggravation of soil erosion.

Abstract:[Objective] The driving factors of ecological environmental changes in the Bailong River basin from 1990 to 2020 were determined in order to provide a scientific basis and decision support for the sustainable development of the Bailong River basin.[Methods] Landsat TM/OLI image data from the vegetation growing season (June to September) were obtained from the Google Earth Engine (GEE) platform and screened year by year. From these data, the four ecological indicators of greenness (NDVI), humidity (WET), heat (LST), and dryness (NDSI) were calculated. Principal component analysis (PCA) was used to construct the remote sensing ecological index (RSEI), and the ecological environment of the Bailong River basin was evaluated.[Results] From 1990 to 2020, the mean RSEI value in the Bailong River basin increased from 0.531 to 0.675, indicating that the ecological and environmental quality had generally improved. The area of ecological and environmental quality improvement was mainly located along the two banks of the Bailong River in the Zhouqu-Wudu section, Northwest Tanchang County, and the east bank of the Minjiang River, with an area of 8 393.97 km², comprising 45.55% of the total area. The influence degree of each ecological index on the ecological environmental quality followed the order of NDSI>WET>LST>NDVI in 1990; NDSI>NDVI>WET>LST in 2006; NDVI>WET>NDSI>LST in 2020.[Conclusion] Using the GEE platform to implement the RSEI model expanded the ability to monitor and evaluate the regional ecological environmental quality over a large area and for a long time period. In recent years, the ecological environmental quality of the Bailong River basin has generally improved, but protection and management of the basin will need to continue.

Abstract:[Objective] The land cover during the grain for green project (GGP) at Chaoyang City, Liaoning Province were analyzed, and the trend of inter annual land class changes were tracked and monitored, and the impact of the project on barren hills, cultivated land, woodlands, and grasslands at Chaoyang City were discussed, in order to provide scientific support for the rational planning and utilization of land resources at Chaoyang City.[Methods] We used the C5.0 algorithm with Landsat images from 1985 to 2020 to extract the spatial-temporal distribution information of land cover in the region. The dynamic changes and driving factors of forest and grassland in a mountainous area during the 36-year study period were determined by means of land use dynamic attitude and a land use transfer matrix.[Results] ① During the past 36 years, the afforestation area of barren hills at Chaoyang City reached 2 745.5 km², and the afforestation area of cultivated land was about 933 km². GGP had achieved remarkable benifits. ② The returned farmland and reforestation areas were mainly located in areas with slopes >25° and altitudes over 500 m. The changes were mainly reflected in the transformation of the internal structure, that is, increasing the proportion of arable land with elevations below 500 m and slopes <25°, basically meeting the requirements of the GGP policy.[Conclusion] The barren hills, cultivated land, forests and grassland of Chaoyang City in the five GGP stages were transformed from one year to another. Compared with the first three GGP stages, the "reverse process" phenomenon in the latter two GGP stages was reduced in response to policy adjustments and implementation. In terms of project implementation, it will still be necessary to strengthen supervision, accurately understand national policies and project technical regulations, and implement policies according to local conditions.

Abstract:[Objective] The key ecological restoration areas for water conservation in the Hanjiang River basin were identified, and the allocation of vegetation was optimized, and to verify the effects of ecological restoration was verified in order to provide a scientific basis for the implementation of ecological restoration projects.[Methods] The InVEST model was used to estimate the water conservation amount in 2020, and the key ecological restoration areas were identified according to the strength of the water conservation function. The ecological restoration scope was defined as the area with forest land, shrub forest, grassland, unused land, and cultivated land with slopes greater than 25° in the weak water conservation function area. A forest land suitability evaluation was carried out at the restoration area. The optimal configuration between land cover types was simulated, and the water conservation function of the restoration area after the configuration and completed was compared with the water conservation function before the configuration.[Results] Water production in the restoration area decreased by 6.97% after the optimal allocation of vegetation, and the total amount of water conservation increased by 14.96%.[Conclusion] The Hanjiang River basin has potential to improve water conservation by means of vegetation optimization allocation. In the future, the restoration area of the Hanjiang River basin should be identified by considering other ecological service functions on the basis of water conservation, and more comprehensive restoration measures should be taken to solve the ecological problems of the Hanjiang River basin.

Abstract:[Objective] The temporal and spatial variation characteristics of water yield and differences in the water yield function for different land use types, soil types, and topography in the Nanbei Panjiang River basin were analyzed in order to provide a scientific reference for the effective management of water resources and ecological restoration in the basin.[Methods] The spatial and temporal variation characteristics, internal differences, and the influence of vegetation restoration on the water yield function in the Nanbei Panjiang River basin from 2005 to 2020 were quantitatively evaluated using the InVEST model.[Results] The average total water yield in the basin fluctuated slightly from 2005 to 2020, showing a trend of higher in the northeast and central regions and lower in the southwest. The overall water yield pattern was spatially consistent with the spatial and temporal changes of precipitation. Without considering the significant change of rainfall, the decrease of cultivated land and grassland areas was the main reason for the slight fluctuation and downward trend of total water yield in the basin. The land use type with the strongest water yield capacity was construction land, followed by bare land, cultivated land, and grassland. The water yield capacities of evergreen coniferous forest and shrub land were weak. The water yield capacity in the basin gradually decreased with increasing altitude, and the soils with strong water yield capacity were mainly yellow soil and red soil. The high water yield areas in the basin were mainly concentrated in the northeast and central regions having low and medium altitudes, and were mainly yellow soil and red soil. The low value area was mainly concentrated in the southwest region having high and higher altitudes with large amounts of lime (rock) soil and purple soil.[Conclusion] The spatial pattern of water yield in the basin exhibited some changes, and the high value area of water yield had a tendency to shift to the east and northeast. Land use type, meteorological factors, soil texture, topography, and other factors have an important impact on the spatial heterogeneity of the water yield function.

Abstract:[Objective] The mountain flood runoff on the west bank of Dianchi Lake was simulated and calculated in order to provide a scientific basis for constructing flood interception facilities, reducing mountain flood disasters, and protecting the water environment of Dianchi Lake.[Methods] We used the SCS-CN runoff model with 33 field-measured rainfall-runoff datasets for the mountainous area on the west bank of Dianchi Lake in Kunming City in 2019 and 2020. The curve number (CN) value was optimized and set according to the slope combined with previous rainfall. The initial abstraction coefficient (λ) was optimized by the exhaust method. Simulation accuracy and parameter applicability for the optimized SCS-CN model were verified by 19 field-measured rainfall-runoff datasets in 2021.[Results] ① The CN value obtained by the slope and previous rainfall classification optimization was only suitable for small and medium rainfall amounts (<30 mm). For heavy rainfall (≥ 30 mm), the antecedent moisture condition (AMC) in the standard SCS-CN model should be modified by linear interpolation according to the total rainfall amount in the previous five days, and then the corresponding slope CN correction value should be determined. ② The optimal λ values for small and medium rainfall events and for heavy rainfall events in the mountainous area on the west bank of Dianchi Lake were 0.15 and 0.20, respectively. ③ The NSE values after model verification for small and medium rainfall and for heavy rainfall were 0.852 2 and 0.797 8, respectively, and the model accuracy rates were 93.33% and 75%, respectively.[Conclusion] The optimized SCS-CN model was considered to be feasible for calculating runoff under the conditions of small and medium rainfall (<30 mm) and heavy rainfall (≥ 30 mm) in the mountainous area on the west bank of Dianchi Lake, and therefore can provide a scientific basis and theoretical reference for the prediction of surface runoff and the further optimization of the SCS-CN model in this area.

Abstract:[Objective] The regional landscape ecological risks were evaluated, and their spatiotemporal variation was analyzed in order to provide important support for reducing regional ecological risks, maintaining regional ecological security, and promoting regional green development.[Methods] We constructed a landscape ecological risk assessment model based on land use change, and determined the temporal and spatial change characteristics of landscape ecological risk for the Ya'an-Kangding Expressway crossing counties and cities from 2000 to 2020. A geographic detector model with optimized parameters was used to quantitatively analyze the driving factors of landscape ecological risk change. We used the PLUS model to simulate the spatial distribution characteristics and changing trends of landscape ecological risks for the Ya'an-Kangding Expressway passing through counties and cities in 2035.[Results] ① From 2000 to 2020, the main landscape types in the study area were forest land, grassland, and cultivated land, with the fastest growth rate occurring for the impervious surface area (expressway), and the largest increase occurring in forest land area. ② Low and medium landscape ecological risk grades were the main factors. The risk grades spread outward from high to low. ③ Natural factors such as NDVI, elevation, and average annual precipitation were the main driving factors for changes in landscape ecological risk. ④ In 2035, the areas of medium, high, and high risk grades in the study area will decrease under the two different scenarios. The area of significant decline will be particularly obvious under the ecological protection scenario.[Conclusion] The landscape ecological risk levels in the study area were relatively low, mainly low, lower, and medium risk levels, and the ecological environment was gradually improving. The ecological protection scenario was more consistent with the concept of regional sustainable development.

Abstract:[Objective] The area, intensity and dynamic changes of soil and water loss in the Ten Tongduis of the Yellow River were analyzed in order to provide a reference for the comprehensive management of the basin.[Methods] Based on the national remote sensing survey results of soil erosion and the national dynamic monitoring results of soil and water loss, the distribution and dynamic changes of soil and water loss in the basin were compared and analyzed.[Results] The vegetation area accounted for 63.97% of the Ten Kongduis of the Yellow River basin, mainly with medium-low and low vegetation coverage accounting for 48.85% and 36.54% of the vegetation coverage area respectively. The area of soil and water loss was 4 374.98 km², accounting for 40.63% of the basin area in 2021. Compared with 2021, soil and water loss were lower in 2020, 1999, and 1985 by 46.32, 3 664.50, and 4 958.03 km², respectively. Soil and water loss were mainly located in grassland, forest land, arable land and other land, accounting for 96.69% of the total area of soil and water loss.[Conclusion] The Ten Kongduis are still a difficult area to control soil erosion in the Yellow River basin. The reduction of high intensity erosion is related to the failure to consider channel erosion in annual monitoring results. This area should adhere to the comprehensive management strategy of "vegetation construction based on Hippophae rhamnoides planting, engineering layout focusing on the construction of silting dam, sand control policy based on the premise of border locking and sand fixation, and vigorously promote the pilot project of sand containment and water exchange".

Abstract:[Objective] The particle size distributions (PSD) of different soils measured by scanning electron microscopy (SEM) and by the pipette method (PM) in the water erosion region of China was compared in order to provide a reference for the determination of typical soil PSDs and their applications in soil erosion models.[Methods] Five typical soils corresponding to the five water erosion subregions of China (i.e., black soil, cinnamon soil, loess, purple soil, and red soil) were collected and analyzed by PM and SEM. Specifically, soil suspensions of different size classes obtained by PM (i.e., < 100, < 53, < 20, < 10, < 5 and < 2 μm) were measured using SEM. The PSD results determined by PM and SEM were compared and the causes for their difference were determined.[Results] For most soil suspensions obtained by PM, particles larger than the corresponding size classes of the suspensions were detected by SEM. As the size classes of soil suspensions decreased, both the count and volume fractions of the corresponding sizes, as measured by SEM, decreased. For the suspensions < 100 μm, the particles of the black, cinnamon, and purple soils fell mainly in the 20-53 μm class, resulting in relatively lower values of SEM-derived mean volume diameter (MVD). In contrast, the primary size classes of the loess and red soil were 20-53 and 53-100 μm, leading to larger MVD. Little difference was observed in the PSDs of loess between PM and SEM for the suspension < 100 μm. Compared with SEM, PM overestimated the clay fractions < 2 μm of the other soil samples, and underestimated the size fractions of 20-53 μm for the black, cinnamon, and purple soils, as well as the fractions of 20-100 μm for the red soil. As a result, the PM-derived mean weight diameters (MWD) were smaller than the SEM-derived MVD for all of the investigated soils. Additionally, the PSD discrepancies between the two analytical methods shifted the textural classes of 84.6% of the total soil samples. Converting the PM-derived PSD with the optimal S-curve models, the proportion of the samples with different textural classes due to PSD analytical method decreased to 61.5%.[Conclusion] Based on the SEM results, PM tended to misestimate the PSDs of all of the five typical soils in the water erosion region. The PSD differences between the two methods varied with soil type and were mainly related to soil mineral composition and clay mineral types.

Abstract:[Objective] The effect of land ecological security at border areas in Guangxi Zhuang Autonomous Region, and the process for improving border areas and enriching people were evaluated scientifically, and the coupling coordination mechanism was revealed in order to provide a reference for promoting border revitalization and regional coordinated development.[Methods] The study was conducted for the eight counties in the border areas of Guangxi. We analyzed the spatial-temporal characteristics of the coupling coordination between land ecological security and the process of prospering the frontier and enriching people in Guangxi border areas from 2000 to 2020. We used the entropy weight TOPISIS comprehensive evaluation method and coupling coordination model.[Results] ① The land ecological security index of border areas gradually increased over time, with the overall ecological security index increasing from 0.213 to 0.728. The land ecological security of each county exhibited different growth rates. The regional differences decreased, showing an overall spatial pattern of "high in the north and south, low in the middle". ② The overall coordination level of the process of prospering the frontier and enriching the people has rose from 0.176 to 0.631, following a pattern of "decrease-increase". Regional differences were not obvious. The grade difference of the process of prospering the frontier and enriching the people in each county was not obvious, and the overall pattern changed little. The development advantages of Pingxiang and Dongxing City, which are important national ports, become more and more obvious. ③ The coupling coordination degree of the land ecological security system and the process system of prospering the frontier and enriching the people was increasing day by day, rising from 0.440 to 0.823, and the coupling degree of the two followed a pattern of "decrease-increase". The spatial feature gradually evolved from "overall dispersion" to "high in the north and south, low in the middle". Driven by the "dual-core" radiation of Pingxiang and Dongxing City, the coordination type was gradually evolving from mild disorder and imminent disorder to primary coordination.[Conclusion] The national strategy of prospering the frontier, enriching the people, and ecologically protecting the environment requires strengthening the innovation of border policy, coordinating the superposition effect of multiple factors, and continuously improving the ecological security and happiness index of border residents.

Abstract:[Objective] The coupling and coordinated development level of water-food-energy-ecological environment (WFEEc) at Lincang City, Yunnan Province was evaluated and an evaluation index system of WFEEc coupling and coordinated development at Lincang City with a sustainable development goal (SDGs) index as the entry point was constructed in order to provide a reference for realizing the coupling and coordinated development of WFEEc in multi-ethnic underdeveloped border areas.[Methods] Based on the four characteristic layers of "pressure, state, influence, and response", an SDGs index system was constructed to evaluate the WFEEc coupling and coordination level at this stage. At the same time, a barriers model and multiple stepwise regression analysis were used to reveal the influencing factors of WFEEc coupling and coordination development.[Results] ① From 2010 to 2020, the WFEEc coupling coordination level of eight counties and districts at Lincang City showed an upward trend, from general coordination to good coordination (the overall coupling coordination degree of Lincang City fluctuated between 0.51 and 0.63), with obvious spatial heterogeneity. ② During the study period, the main obstacle factors of Lincang City gradually decreased, but the obstacle degree of the energy subsystem always crossed and increased year by year. ③ The main factors hindering WFEEc coupling and coordination were the national financial education funds of Linxiang District, the average wages of non-private employees at Zhenkang County, the per capita GDP of Fengqing County and Cangyuan County, the urbanization rate of Yongde County and Shuangjiang County, the per capita GDP of Yunxian County, the water resources, the centralized treatment rate of the sewage treatment plant, the national financial education funds, and the urbanization rate and water resources of Gengma County.[Conclusion] From 2010 to 2020, the coupling coordination degree of WFEEc at Lincang City had gradually improved, but the value of coupling coordination degree was still low. All counties and districts still need to actively implement and take relevant targeted measures to continuously optimize relevant policies and measures that promote WFEEc coupling and coordinated development level of all counties and districts, while strongly promoting the steady implementation and gradual improvement of policies for the development model of one characteristic industry at a county. The sustainable development and innovation driven development capacity of the Lincang Sustainable Development and Innovation Demonstration Zone has been steadily enhanced. This enhancement will play an increasingly important demonstration role as it radiates its influence in driving construction at the Lincang National Sustainable Development Innovation Demonstration Zone and WFEEc coupling and coordinated development in similar border areas.

Abstract:[Objective] The water resource carrying capacity and appropriate population size of main provincial capitals in China were analyzed in order to provide a reference for implementing the policy of "determining population by water resources" and the strategy of urban sustainable development.[Methods] Based on water resources and population data, we used the ecological footprint method to analyze the ecological footprint of water resources and their water resource carrying capacity in the provincial capital cities of China from 2010 to 2020. The quota method was used with current domestic water consumption data to estimate the suitable carrying population scale for each provincial capital.[Results] ① More than half of the provincial capitals had less than 500 m³ of water per capita per year, and the domestic water consumption of most cities accounted for 20% of the total water consumption, while the domestic water use of Beijing City and Zhengzhou City accounted for 45% of the total water consumption. This high proportion of domestic water use put the urban water supply under great pressure. ② Cities with high per capita water resources have an ecological surplus of water resources. However, about two-thirds of the provincial capitals were in a state of ecological deficit. The highest per capita surplus from 2010 to 2020 was found for Nanning City (2.20 hm²/person). The greatest per capita deficit was found for Yinchuan City (-1.66 hm²/person). The distribution of ecological surplus and deficit of water resources showed a pattern of "surplus in the south, deficit in the north", but some provincial capitals in the middle and lower reaches of the Yangtze River also showed deficits. ③ The suitable population in provincial capitals was evaluated based on the two water consumption scenarios of "extensive consumption" and "conservative consumption". There was a large difference between the suitable population and the current population.[Conclusion] In order to promote sustainable economic and social development, cities with serious waste of water resources should strengthen the construction of water-saving cities, while cities with low domestic water standards should consider reducing their population in order to improve the water using experience and the quality of life of residents.

Abstract:[Objective] The spatial and temporal evolutionary characteristics of arable land in the Tumen River basin and the driving factors for changes in arable land area were explored, and changes in arable land area associated with the Land Spatial Planning of Jilin Province (2021-2035) were predicted in order to provide a decision support basis for the rational planning and utilization of arable land resources in the Tumen River Basin.[Methods] Spatial and temporal evolution characteristics of arable land were explored through an analysis of a land use shift matrix and a center of gravity shift analysis. Markov and PLUS models were coupled to predict the quantity and spatial changes of cultivated land area under different scenarios.[Results] ① The total area of arable land has been decreasing continuously since 1990, but the overall situation was under control. The total area had decreased by 440.42 km² by 2020, with arable land having been mainly transformed into forest land and construction land. ② There were obvious differences in the spatial distribution of arable land, with arable land concentrated in the middle and lower reaches of the river basin. The center of gravity of arable land gradually shifted to the southwest at a rate of 43.1 m per year. ③ Socioeconomic factors (GDP, road traffic, population) and natural factors (slope, precipitation) were the main drivers influencing arable land changes in the past. ④ The total amount of arable land for both scenarios decreased over time. The total area of arable land in 2035 in the goal-oriented scenario will be 128.57 km² less than in 2020. The reduction in arable land will be concentrated mainly in the planned development zones and protected areas.[Conclusion] Pressures on arable land in the study area have increased because of rapid socioeconomic development over the past 30 years, and the current trends are not conducive to achieving the land spatial planning goals. In order to protect arable land quantity, quality, and ecology, and to sustainably develop arable land resources, those resources in the upstream and western areas of the study area must be developed appropriately so that the scale and technology of original agriculture can be promoted. Additionally, goal-oriented scenarios are more conducive to the sustainable development of arable land resources in the Tumen River basin, and land spatial planning goals should continue to be implemented.

Abstract:[Objective] The characteristics and driving factors of landscape pattern changes and the spatiotemporal evolution of landscape ecological risk was analyzed in order to provide a theoretical basis for integrated watershed management, watershed ecosystem management, and sustainable development.[Methods] A landscape ecological risk assessment model was proposed using the landscape index method based on land use data in 2000, 2010, and 2020 from the Huangshui River basin. Spatiotemporal dynamic characteristics of landscape patterns and ecological risk were examined by coupling ArcGIS 10.6, Fragstats 4.2, and GeoDa 1.20. Factors driving spatially stratified heterogeneity of landscape ecological risk were identified using geographic detectors.[Results] ① Grassland and cropland were the dominant land use types in the Huangshui River basin. Land transfer mainly occurred between cropland, grassland, and construction land. Urban expansion was the main feature of land use/land cover changes over the past 20 years. ② From 2000 to 2020, landscape ecological risk in the Huangshui River basin initially increased and then decreased, and there was a negative correlation between ecological service value and landscape ecological risk. ③ Spatial distributions of landscape ecological risk in the Huangshui River basin mainly presented "high-high" and "low-low" agglomerations. Elevation was the main factor driving the spatially stratified heterogeneity of ecological risk. The interaction between driving factors had an enhancing effect on spatially stratified heterogeneity of landscape ecological risk. ④ Spatial distribution of landscape ecological risks had an obvious altitude gradient effect. According to the altitude gradient, the Huangshui River basin was divided into three ecological risk control zones:key control area, strict control area, and general control area.[Conclusion] Ecological governance and ecological restoration were the main reasons for the decline of the landscape ecological risk index in the Huangshui River basin. Different management and control strategies should be implemented for different ecological risk control zones. Land use optimization management and land use control should be primary concerns with respect to ecological risk control.

Abstract:[Objective] The supply and demand of water yield services in the Pakistan section of China-Pakistan economic corridor were analyzed, the risk areas for water yield services were identified scientifically, and the risk prevention measures were formulated reasonably in order to provide an important basis for the green development of the China-Pakistan economic corridor.[Methods] Based on remote sensing image data and socio-economic data for 2000, 2005, 2010, 2015, and 2020 from the research area (the Pakistan section of the China-Pakistan economic corridor), the InVEST model and the human-demand method were used to estimate the supply and demand of water yield services. The supply and demand index and trends were used to assess the supply and demand risks of water yield services and to delineate risk areas.[Results] ① Total water yield from 2000 to 2020 initially increased and then decreased. The water yield service supply capacity was high in the center of the study area and low in the north and south. The total demand for water yield increased by 58.44% over the past 20 years. ② From 2000 to 2020, the supply and demand index of water yield services had a weak trend and was generally stable. Severe deficit areas were mainly located in the Indus Plain and Western Balochistan, and high surplus areas were concentrated in Gilgit-Baltistan and Eastern Balochistan. ③ The high-risk areas accounted for 22.69% of the national area, and the type of supply and demand match was mainly low supply and low demand (47.57%).[Conclusion] Dynamically assessing water yield in the China-Pakistan economic corridor (Pakistan section), formulating regional water resource protection measures, and constructing an ecological compensation mechanism to balance the supply and demand of water yield services are conducive to promoting the green development of the China-Pakistan economic corridor.

Abstract:[Objective] The spatial and temporal changes of ecological environmental quality (EEQ) in response to climate and land use changes on the Loess Plateau were analyzed in order to provide a basis for the formulation of reasonable ecological protection measures and land development on the Loess Plateau that will promote high-quality development.[Methods] Based on an improved remote sensing ecological environmental index and climate and land use data, we determined the spatial and temporal characteristics of EEQ on the Loess Plateau from 2001 to 2020 using Theil-Sen trend analysis at the image pixel scale.[Results] ① During the study period, EEQ values on the Loess Plateau showed small fluctuations of rising, falling, and rising, and the fluctuations slowed down from 2010 to 2020 compared with the time period of 2001 to 2010. EEQ values generally showed a spatial pattern of "higher in the southeast and lower in the northwest". Compared with the period from 2001 to 2010, the period of 2010 to 2020 exhibited an area of significant increase in EEQ that shifted from the southeast to the north-central region, and an area of significant decrease in EEQ that shifted from the northwest to the east. ② Precipitation had an overall positive effect on EEQ, with a significant positive correlation from 2001 to 2007. Due to the interference of other factors in the later period, the driving force increased, and the influence was small in areas with less vegetation coverage. Temperature had a negative effect on EEQ in most areas, with less effect compared with precipitation, and greater effect in dense urban areas. ③ During the study period, large transfers of cropland to grassland, grassland to woodland, and unused land to grassland were the main driving forces for the steady to good pattern of EEQ in the study area, while the transfer of cropland to construction land and of grassland to unused land were important factors causing the decline of EEQ.[Conclusion] EEQ on the Loess Plateau was influenced by both climate and land use. The influence of precipitation on EEQ was greater than that of temperature, and land use shifts generally showed positive effects on EEQ but with spatial heterogeneity. Greater attention should be given to regional ecological conservation in urban clusters within the region in the future.

Abstract:[Objective] The spatial and temporal evolution patterns and driving mechanisms of multifunctional cropland were analyzed in order to provide support for ensuring food security and promoting the coordinated development of regional multifunctional cropland along with socio-economic development.[Methods] The entropy power method, hierarchical analysis method, comprehensive index method, GIS spatial visualization analysis, and geographic probe were used in this study.[Results] ① The comprehensive function of arable land in each county of Poyang Lake p lain generally increased from 2000 to 2020, and was significantly influenced by socio-economic development level. Specifically, improvement of the comprehensive function of arable land was given priority to areas with faster socio-economic development, such as Nanchang County, Anyi County, and other areas around Nanchang City. ② Different trends of multi-functional changes were observed for arable land in Poyang Lake plain during the 20 years of the study. Production and landscape aesthetic functions showed a growing trend, while ecological maintenance and social security functions show a decreasing trend. These patterns indicated that even though the production function of arable land in Poyang Lake plain improved, it was difficult to guarantee the growing food and economic demand, while the rapid development of secondary and tertiary industries gradually decreased the proportion of economic contribution that arable land can provide. ③ The multi-functional development level of arable land in Poyang Lake plain was influenced by both social and natural factors. The social factors could be regulated by policies such as improving the basic conditions of agricultural production, guaranteeing the minimum income of rural residents, and improving the medical welfare standard of rural residents, while the natural environment requires human intervention to protect and restore the ecological environment.[Conclusion] A variety of factors jointly influenced the level of multifunctional development of arable land in Poyang Lake plain, and the rational formulation of policies related to the protection and utilization of arable land and the protection of rural residents' living standards that have a facilitating effect on improving the level of multifunctional development of arable land.

Abstract:[Objective] The dynamic changes of vegetation and its response relationship with topography in Changbai Mountain were explored in order to provide scientific support for ecological environmental protection and management in this mountainous area.[Methods] Based on MODIS NDVI and DEM data, fractional vegetation cover in Changbai Mountain from 2000 to 2020 was estimated using a pixel dichotomy model. Spatiotemporal variations of fractional vegetation cover were analyzed in depth using Sen+Mann-Kendall trend analysis, spatial autocorrelation analysis, and a center of gravity migration model. At the same time, the differential effects of vegetation cover variations were quantitatively determined by combining the analysis results with the correction coefficient for topographic areas in this study in terms of elevation, slope, and aspect factors.[Results] ① In terms of spatiotemporal distribution, the fractional vegetation cover in Changbai Mountain increased at a rate of 0.023 7/10 yr (p<0.001) from 2000 to 2020 and underwent an obvious upward mutation in 2010, showing a distribution pattern of "high around and low in the middle", with an overall level of high. ② In terms of spatiotemporal variation, the area of vegetation improvement in Changbai Mountain was much larger than the area of degradation from 2000 to 2020, showing a significant clustering state dominated by a "high-high" pattern. However, the degree of clustering showed a fluctuating downward trend, and the center of gravity of vegetation cover generally migrated to the southwest during the 21-yr study period. ③ In terms of topographic differentiation, the fractional vegetation cover in Changbai Mountain increased and then decreased with the increase of elevation and slope over time. During different time periods, vegetation in the areas of elevation <600 m, ≥ 1200 m and slope <2°, ≥ 25° generally showed a degradation trend. The areas primarily showing improvement or stabilization over time had elevations of 600-1 200 m and slopes of 2°-25°. The trend of vegetation degradation was obvious in the flat land area, while little difference in the variation types was observed for other aspects.[Conclusion] The vegetation condition of Changbai Mountain has generally improved over the past 21 years. Spatial differentiation of vegetation variations under different elevations and slopes was obvious, while the effect of aspect on vegetation variations was not significant.

Abstract:[Objective] The international research situation, current research status, and trends in research hotspots in the field of gully erosion at home and abroad from 1991 to 2020 were analyzed, and the development trends of gully erosion measurement techniques and models were analyzed quantitatively in order to promote the in-depth development of gully erosion research and provide reference information for scholars in related fields.[Methods] We acquired 2 568 research papers dealing with gully erosion from the Web of Science from 1991 to 2020. We used a bibliometric analysis method and VOSviewer software to analyze the research situation of countries and institutions and the change trend of hotspots for gully erosion research.[Results] The number of papers published on gully erosion research presented an upward trend in the recent 30 years, and rose rapidly from 2011 to 2020. China (23.7% of papers) and the United States(20.8%) were the main countries conducting and publishing gully erosion research, with 44.5% of the word's publications, and close cooperation between the two countries. Among the top ten institutions conducting global gully erosion research, three institutions (the Chinese Academy of Sciences, Northwest University of Agriculture and Forestry, and Beijing Normal University) were located in China. This field of research involved many disciplines, most of which were related to geology. Influencing factors, measurement techniques, and gully erosion research models were the main research focuses in the field of gully erosion. The impact factors of runoff, land use, vegetation, rainfall and soil had always been the focus of gully erosion research. The impact of climate change, especially extreme rainfall, received greater attention in recent years. High precision 3D stereo measurement technology gradually replaced 2D plane measurement technology, and was widely used. Empirical models were applied early and widely. Estimation models based on quantitative analysis began to be established after 2000, and this devlopment improved the accuracy of gully erosion monitoring and prediction.[Conclusion] Future gully erosion research should focus on the formation of gully erosion under extreme rainfall after vegetation restoration, interaction of different factors on the gully erosion process, development of new methods for gully erosion monitoring, and developing prediction models of gully erosion processes.

Abstract:[目的] 分析安徽省2000年以来碳储量的时空变化及空间分布特征，为未来该区土地管理决策和生态系统碳库管理提供有效指导。[方法] 以安徽省为例，基于2000，2005，2010，2015，2020年5期土地利用数据，采用PLUS模型模拟2030，2040年不同情景下土地利用格局，并运用InVEST模型定量评估不同情景下陆地生态系统碳储量的空间变化。[结果] ①2000—2020年安徽省约有8.03%土地发生了转移，耕地与建设用地之间的转化是该省土地利用变化的主要特征。②2000—2020年陆地生态系统碳储量总体呈下降趋势，下降了1.01×10⁸ t。空间格局上呈现“南高北低”的特征，碳密度高值区主要分布在皖南、皖西山区。③2020—2040年自然发展情景下碳储量下降趋势明显，耕地保护情景下降速度有所减缓，生态保护情景下碳储量明显增加，增量为3.07×10⁷ t。[结论] 实施生态保护政策能够有效提高区域生态系统碳储量，增强生态系统服务功能。未来在进行土地利用管理决策时应统筹考虑生态保护和耕地保护，促进区域生态系统良性可持续发展。

Abstract:[Objective] The temporal and spatial characteristics of carbon storage in the Poyang Lake wetland ecosystem were analyzed in order to provide scientifically based recommendations to protect Poyang Lake wetlands in the future and to produce regional "carbon peak and carbon neutrality".[Methods] InVEST and GeoSoS-FLUS models were combined to calculate carbon storage of typical wetlands in the Poyang Lake region from 2000 to 2020, and to predict carbon storage changes in 2030 under natural development scenarios and ecological protection scenarios. The factors driving carbon storage changes were determined by means of the geographic detector model.[Results] ① The carbon reserves of typical wetlands in the Poyang Lake region in 2000, 2010 and 2020 were 2.42×10⁶ t 2.48×10⁶ t and 2.46×10⁶ t, respectively. ② The high carbon reserves were concentrated in the central and western forests, while the low carbon reserves were concentrated in the east, central, western and northern lakes. ③ Land use was the dominant factor affecting carbon storage transfer. The explanatory power of vegetative cover type with respect to carbon storage transfer followed the order of marsh grassland> marshland>forest land>cultivated land. ④ Compared with the natural development scenario, the change rate of carbon storage for the ecological protection scenario changed from -17.81% to -1.09% during the period from 2020 to 2030.[Conclusion] Reasonable ecological protection policies can effectively guarantee the carbon sequestration capacity of wetlands. Land use control practices should be strengthened and ecological protection measures should be implemented as as to guarantee improvement in regional carbon storage capacity.

Abstract:Objective The spatial and temporal distribution pattern and evolution characteristics of ecosystem carbon storage, its response to land use change, and the vulnerability of ecosystem carbon storage service in each county of Guizhou Province were analyzed in order to provide a scientific basis and reference for regional land use management decision-making and to realize the "dual carbon" goal. Methods The InVEST model and the potential impact (PI) index were used to analyze the characteristics of carbon stock changes and the vulnerability of ecosystem carbon storage services in Guizhou Province from 2000 to 2020. Results ① Land use type in Guizhou Province changed significantly during the last 20 years. 14.10% and 17.29% of the land changed type in the first 10 years and the last 10 years, respectively. Cultivated land was the main source of construction land expansion. ② Ecosystem carbon storage in Guizhou Province decreased by 0.24 billion tons in the past 20 years. Forest land reductions and construction land expansion were the main reasons for carbon storage reduction. ③ All Moran's I indices of ecosystem carbon stocks in Guizhou Province exceeded 0, indicating significant positive spatial correlation and agglomeration. The hot spot/cold-spot analysis showed that the distribution of carbon stock hot spots was relatively decentralized while the distribution of cold spots was centralized and stable. ④ The PI indices for Guizhou Province in the first and second 10-year periods were -1.27 and -0.15, respectively, indicating an improvement in vulnerability. There were spatial differences in vulnerability among counties, with significant negative effects in the peripheral counties. The vulnerability of 81.82% of the counties decreased in 20 years. Conclusion The transfer of forest land and the expansion of construction land in Guizhou Province had a significant impact on carbon stocks and the vulnerability of carbon stock services. In the future, land use structure should be optimized, and planning and management should be strengthened.

Abstract:[Objective] The spatial and temporal distribution characteristics of land use carbon sources/sinks in the Huainan mining area from 2000 to 2020 were analyzed, in order to provide a basis for Huainan City's territorial spatial planning and future low-carbon regulation policy formulation.[Methods] The study was conducted in the Huainan mining area. Grid-scale land use data in 2000, 2010, and 2020 were used to quantify the spatial and temporal patterns of carbon sources/sinks/emissions under different stages of land use change development. The spatial patterns of carbon sources/sinks/emissions were determined based on coldspots and hotspots.[Results] ① From 2000 to 2020, the land use type shifted from a single land use type to multiple land use types at the same time. The area of construction land increased, leading to an enhanced carbon source effect, a relatively weaker carbon sink effect, and a continuous increase in carbon emissions, with an annual increase in carbon sources of 2.76×10⁶ t, an annual increase in carbon sinks of only 130 t, and an annual increase in carbon emissions of 2.76×10⁶ t. ② The spatial distribution characteristics of carbon sources and emissions were basically the same, with the central built-up area and the northwest mining area being the main concentration areas of carbon sources and emissions. Carbon sinks were mainly concentrated in the eastern and western fringe areas and the western mining area. ③ The central built-up area of the study area was a significant hotspot area for carbon sources and emissions, dominated by significant hotspot change characteristics. Significant coldspots were mainly located in the eastern and western marginal areas of the study area and in the northwest part of the mining area.[Conclusion] Greater attention should be given to the carbon emission reduction and low carbon effect of the Huainan mining area in the large plain area of farm land in the north, as well as to controlling the mining of coal resources, to the development of construction land, and to rapid restoration of subsidized water areas. With the rapid increase of urbanization in Southern China, the area of productive carbon absorption capacity from forest land and grassland should be moderately increased to avoid unlimited expansion of construction land.

Abstract:[Objective] The carbon storage of the future green space patterns was predicted, and the impact of green space changes on carbon storage was analyzed in order to provide a basis for green space planning in Harbin City, Heilongjiang Province under the dual-carbon policy.[Methods] Based on the green space land cover data of Harbin City in 2010 and 2020, the dual-carbon industry driving factors were introduced into the FLUS model, and the changes in green space land cover under different scenarios in 2030 were predicted. The carbon storage values in 2010, 2020, and 2030 were calculated using the InVEST model. The spatial-temporal variation of carbon storage was compared and analyzed, and the influence of green space on carbon storage was discussed.[Results] ① After the dual-carbon industry factors were introduced into the FLUS model, the kappa coefficient increased by 1.30%, and the root mean square error decreased by 0.21% compared with the original model, indicating increased simulation accuracy of the improved model. ② From 2010 to 2020, carbon storage decreased by 5.14×10⁶ t, primarily as result of decreased cultivated land. Carbon was primarily stored in the aboveground biomass carbon pool and the soil carbon pool, accounting for 88.52% of the total carbon reserves. ③ Carbon storage under natural development, ecological protection, and economic development scenarios in 2030 were 2.58×10⁹, 2.58×10⁹, and 2.58×10⁹ t, respectively, showing a downward trend from 2020. The decline rate in the ecological protection scenario was the slowest of the three scenarios, and was 0.12 times the rate observed for the natural development scenario.[Conclusion] In the future, ecological protection and restoration measures should be strengthened to reduce the loss of cultivated land and forest land, and the expansion of non-green space should be controlled in order to improve carbon storage in Harbin City.

Abstract:[Objective] Soil erosion and its associated carbon loss in an alpine meadow on the Tibetan Plateau were quantitatively analyzed in order to provide a reference for comprehensively evaluating the impact of soil erosion and for implementing effective soil and water conservation measures.[Methods] We used ¹³⁷Cs tracing technology combined with the results of previous research studies to determine erosion rate and consequent carbon loss for an undisturbed alpine meadow soil on the Tibetan Plateau.[Results] The undisturbed meadow soil exhibited three distinct layers (A, B, and C) of physiochemical properties, and the distribution of ¹³⁷Cs declined exponentially with increasing soil depth. The recent erosion rate of the alpine meadow soil was about 77-230 t/(km²·yr), and was estimated to result in an average annual soil organic carbon loss of not less than 4.86 t/km².[Conclusion] Even though the overall soil erosion rate of the alpine meadow on the Tibetan Plateau was low, it's organic carbon loss due to erosion cannot be underestimated. Both increased human activities and reduced meadow growth due to decreased soil moisture under future global warming are likely to result in further soil degradation and soil organic carbon loss in alpine meadows.

Abstract:[Objective] The land use patterns and carbon storage distribution in Handan City, Hebei Province during the recent 20 years were analyzed, and the trends in land use changes under an ecological protection policy duirng the next 10 years were determined, in order to provide evidence for both increasing urban carbon sinks and realizing sustainable urban development.[Methods] Based on the PLUS model, natural and social driving factors were selected to analyze land use change patterns in Handan City in 2030 under the scenarios of natural development and ecological protection from 2000 to 2020. Carbon storage was also evaluated by the InVEST model in Handan City from 2000 to 2030.[Results] ① The spatial distribution of land use types in Handan City showed the characteristics of "woodland in the west and cultivated land in the east". The land use transfer between cultivated land and artificial habitats accounted for 96.58% of the total land use change. ② The spatial distribution of carbon density was characterized as "high in the west and low in the east" in Handan City. Carbon storage decreased over time. Excessive encroachment of cultivated land led to a dramatic increase in carbon loss in Handan City in 2010. Excessive encroachment of cultivated land was the main cause of carbon loss in Handan City. ③ Compared with the natural development scenario, land use change under an ecological protection scenario tended to be restrained. Although the potential for ecological land improvement was average, consumption of ecological resources was avoided due to limited human activities. ④ Under both the natural development and ecological protection scenarios, carbon storage from 2020 to 2030 in Handan City was simulated to decrease by 4.23×10⁶ t and increase by 2.16×10⁴ t, respectively. The risk of carbon loss was significantly reduced across the city, and the potential of carbon sinks in different areas of the city appeared to differ significantly.[Conclusion] The encroachment of cultivated land was the main cause of carbon loss over time. Implementation of ecological protection policies significantly reduced the risk of carbon loss in each district and county, and there are obvious differences among different districts and counties. Carbon loss was more likely to occur in the east-central plain region, while the districts and counties at the eastern foot of the Taihang Mountain in the southwest had strong carbon sink potential, therefore a flexible plan should be made according to location differences.

Abstract:[Objective] The synergistic relationship between land use carbon balance and human activity intensity were studied in order to provide a reference for regional collaborative carbon emission reduction planning in the Tuojiang River basin, and thereby meet the goal of "carbon peak and carbon neutrality" in China.[Methods] Using land use and socio-economic data from 2000 to 2020, carbon emission economic contribution coefficient, carbon ecological carrying coefficient, human activity intensity indicators, a coupled coordination model, and regression analysis, we calculated carbon emissions from land use in the Tuojiang River basin. We then analyzed the spatiotemporal evolution characteristics and synergistic relationship between land use carbon balance and human activity intensity.[Results] Carbon emissions in the Tuojiang River basin increased by 5.13×10⁷ t from 2000 to 2020, with construction land accounting for over 90% of carbon emissions. The small change in carbon absorption mainly resulted from forest land showing a change pattern of initially decreasing and then increasing. The growth rate of net carbon emissions showed a downward trend. The coordination of land use carbon balance in each district and county was improving, but more than 70% of the region was in a state of imbalance and decline. The overall intensity of human activities in the Tuojiang River basin was at a moderate level, with a spatial pattern of "low-high-low-high" from north to south.[Conclusion] There was a significant positive correlation between human activity intensity and per capita GDP and per capita carbon emissions. The negative correlation between land use carbon balance coordination and human activity intensity decreased with technological progress and increased energy utilization efficiency. Improving carbon sequestration capacity and carbon productivity is an effective way to improve the coordination level of regional land use carbon balance. The results of this study provide a reference for regional collaborative carbon emission reduction planning in the Tuojiang River basin.

Abstract:[Objective] The effects of different mulching methods on the distribution of organic and inorganic carbon in soil aggregates on the Loess Plateau, and the mechanism under which soil aggregates sequester carbon under mulched conditions were determined in order to promote efficient management of dryland farm soil.[Methods] The study was conducted on a long-term positioning experiment beginning in 2012. Soil characteristics were studied from plots on which spring corn ("Xianyu 335") was grown under three treatments:straw mulching (SM), film mulching (FM), and no mulching (CK). Carbon distribution and enzyme activities in aggregates of different particle sizes were determined by the wet sieve method.[Results] ① Organic carbon contents of aggregates of each particle size were significantly greater for SM than for CK (p<0.05), with the increases ranging from 4.8% to 18.2%. However, the organic carbon contents for each particle size were significantly decreased for FM (p<0.05) compared with CK, with the decreases ranging from 1.2% to 7.1%. For any given treatment, the organic carbon content of aggregates initially increased and then decreased with decreasing particle size. Organic carbon storage under SM was greater than under FM and CK. ② Inorganic carbon content in aggregates was significantly greater for FM than for CK (p<0.05), with the increases ranging from 4.3% to 5.9%. SM reduced inorganic carbon content compared with CK, but the difference was not significant. For any given treatment, the inorganic carbon content in each particle size of aggregates initially increased and then decreased with decreasing particle size. FM significantly decreased the inorganic carbon reserves of aggregates >2 mm in size, but significantly increased the reserves of aggregates 2 mm to 0.25 mm in size (p<0.05). ③ SM significantly increased the total carbon content of aggregates by 7.1% to 12.4%. Both FM and SM significantly increased the total carbon storage of particles ranging from 2 mm to 0.25 mm (p<0.05). ④ SM increased the activity of carbon cycling-related enzymes in aggregates, while FM decreased the activity compared with CK. Correlation analysis showed that there was a significant positive correlation between organic carbon and total carbon content and carbon cycling-related enzyme activities (p<0.05).[Conclusion] SM and FM significantly affected changes in the carbon pool of aggregates. SM was superior to FM in improving soil fertility and increasing soil carbon fixation.

Abstract:[Objective] The effects of climate change on the stability of organic carbon were revealed from the perspective of the molecular structure of organic carbon in order to provide a theoretical basis for clarifying the impact of future climate change on organic carbon stability and soil fertility in mollisols.[Methods] A long-term field experiment dealing with the simulation of climate change through the use of open-top chambers (OTCs) at the Hailun Agroecological Experiment Station of the Chinese Academy of Sciences provided data for this study. We analyzed the organic carbon content and infrared spectral characteristics of various aggregates and density fractions in the 0-20 cm topsoil of black soil under three treatments:① ambient temperature and CO₂ concentration (aTaCO₂); ② temperature elevated by 2℃ and ambient CO₂ concentration (eTaCO₂); ③ temperature elevated by 2℃ and CO₂ enrichment to (700±25) μmol/mol (eTeCO₂).[Results] Neither eTaCO₂ nor eTeCO₂ significantly affected organic carbon content of the bulk soil compared with aTaCO₂ (p>0.05). However, eTaCO₂ increased soil organic carbon (SOC) contents by 13.45% and 52.89% in the <0.053 mm size aggregates and occluded light fraction (OF), respectively, (p<0.05). eTeCO₂ increased SOC content by 46.89% in the free light fraction (LF) (p<0.05). Compared with aTaCO₂, both eTaCO₂ and eTeCO₂ treatments significantly influenced the SOC molecular structure of the bulk soil. The relative intensity of other functional groups was significantly affected, except for the aliphatic group (p<0.05). Moreover, eTeCO₂ weakened the aliphatic group of organic carbon in the bulk soil and the >0.25 mm size aggregate, but increased the -CH/C=C ratio of organic carbon in the 0.25-0.053 mm size aggregates (p<0.05). Alcohols, aliphatic, aromatic, and polysaccharides were the major functional groups affected by climate change. Furthermore, compared with aTaCO₂, eTaCO₂ and eTeCO₂ increased the -CH/C=C ratio in the LF and OF fractions, accelerating lipolysis in light fractions of organic carbon.[Conclusion] Climate change had no effect on the content of organic carbon in mollisols. Although increased temperature and CO₂ had different effects on the composition and proportion of organic carbon molecular structure, organic carbon storage remained stable in mollisols. Climate change may have little effect on soil organic carbon storage, and the fertility level of the black soil can still be maintained.

Abstract:[Objective] The spatial and temporal characteristics and influencing factors of soil organic carbon loss from sugarcane in a typical small watershed in the red soil area of Guangxi Zhuang Autonomous Region were determined, and the spatial and temporal changes of organic carbon from watershed sediment entering the river during different growth periods of sugarcane were analyzed in order to identify the factors influencing soil organic carbon loss under natural rainfall erosion.[Methods] The experimental area was located in the Nala sub-basin of the water source area of Kailan Reservoir at Fusui County, Chongzuo City, Guangxi Zhuang Autonomous Region. The watershed was divided into the lower sub-basin (S₁) and the upper sub-basins (S₂ and S₃). The organic carbon of incoming sediment and vegetation cover were monitored during four growth periods (seedling, tillering, elongation, and maturity) of sugarcane using UAV technology and an automatic runoff sediment monitoring-sampling system. Pearson correlation analysis was used to determine the relationship between organic carbon of incoming sediment and influencing factors such as rainfall runoff, vegetation cover, and fertilizer application.[Results] ① The organic carbon load of sediment into the river during the seedling stage of sugarcane accounted for 61.1% of the total loss during the entire growing season, and this value was significantly greater than values observed in the other growing periods. Organic carbon load followed the order of seedling stage (5.1 kg/hm²) > maturity stage (1.6 kg/hm²) > elongation stage (1.4 kg/hm²) > tillering stage (0.3 kg/hm²); ② rainfall runoff and vegetation cover were significantly correlated with organic carbon loss from incoming sediment, explaining 45% and 54%, respectively, of the variation in organic carbon loss from incoming sediment during the growing season. Fertilizer application and soil bulk density were significantly correlated with organic carbon loss from incoming sediment in the watershed, explaining 79% and 36%, respectively, of the variation in organic carbon loss from incoming sediment during the growing season.[Conclusion] Studies have shown that organic carbon loss from watershed sediments is mainly influenced by rainfall runoff, vegetation cover, fertilizer application, and soil bulk density. In small watersheds in sugarcane areas, increasing vegetation cover to reduce surface runoff and regulating the timing of fertilizer application can play an important role in reducing soil organic carbon loss.

Abstract:[Objective] The spatio-temporal differentiation and driving factors of farmland ecosystem carbon source-sink effects in Guangdong Province were analyzed in order to provide a valuable reference for the scientific and rational formulation of regional agricultural carbon reduction and carbon sequestration measures in the region.[Methods] Quantitative assessment of the spatial-temporal distribution of carbon source-sink effects in farmland ecosystems in Guangdong Province from 2010 to 2020 was conducted by using the parameter estimation method and GIS spatial analysis. The driving factors of spatial differentiation of the carbon source-sink effect in farmland ecosystems were determined by using the LMDI factor decomposition model.[Results] ① The level of carbon source-sink effects in Guangdong Province farmland ecosystems continued to maintain a good, positive development trend, and the effects of reducing emissions and sequestering carbon gradually became prominent. Specifically, the total carbon sequestration fluctuated and increased, and rice, sugarcane, and vegetables were the main carbon sources. Carbon emissions were effectively controlled, and the effect of reducing emissions was becoming increasingly evident. Rice planting and agricultural inputs were the main carbon sources. Moreover, the growth of carbon sequestration in farmland ecosystems effectively offset the growth of carbon emissions. ② The spatial heterogeneity of carbon source-sink effects of farmland ecosystems was obvious, and the overall distribution was relatively clustered. Zhanjiang was the main high-carbon source-high-carbon sink area, while low-carbon source-low-carbon sink areas were mainly found in the Pearl River Delta region. ③ Economic factors were the key driving force causing increased carbon sequestration in farmland ecosystems, while structural factors exhibited inconsistent responses and varied with their locations. Efficiency factors and labor force factors, on the other hand, had a restraining effect.[Conclusion] The carbon source-sink effect of farmland ecosystems in Guangdong Province exhibited a continuous increasing trend overall, but there were significant regional differences. Therefore, measures to reduce emissions and sequester carbon in agriculture should be tailored to local conditions, taking into account the differences in the driving effects of economic, structural, efficiency, and labor force factors in each region.

Abstract:[Objective] The land use change pattern and its carbon effect in the main grain producing areas were investigated in order to provide a basis for restructuring land use and for low carbon economic development.[Methods] We used multi-period land use status data supported by the grid sampling method, a land use dynamic attitude model, a carbon emission coefficient method, and a spatial autocorrelation analysis model to determine the spatial heterogeneity characteristics of land use change patterns and their carbon effect in the Dongting Lake basin since 1980.[Results] ① Land use in the Dongting Lake basin changed in stages, with a comprehensive dynamic attitude of 0.02% from 1980 to 2000. During this time, the largest dynamic attitude was construction land, followed by unused land. The comprehensive dynamic attitude increased to 0.18% from 2000 to 2020, with accelerated growth in the area of construction land. ② The net carbon effect was manifested as a carbon sink, from 5.93×10⁷ t in 1980 to 2.82×10⁷ t in 2020, while the carbon effect caused by land use change showed that the change in carbon emissions was greater than the change in carbon sinks, leading to an increase in net carbon emissions of 6.08×10⁵ t. High value net carbon emissions were distributed in an "H" shape, and the low value emissions area expanded gradually. ③ The spatial autocorrelation of net carbon emissions in the Dongting Lake catchment area was significant. The main aggregation types were high-high and low-low from 1980 to 2000. The low-high type was scattered, and the high-high type was more concentrated and contiguous from 2000 to 2020, while the low-low type was mainly found in the northern part of the Xiangjiang River basin.[Conclusion] In Dongting Lake basin, people should maintain the orientation of "increasing carbon sinks and reducing carbon emissions", maintain the stable state of carbon sinks in forest land, scientifically guide the development and use of land with high carbon emissions, and give attention to the "assimilation" of carbon emissions in different catchment areas according to the characteristics of spatial autocorrelation.

Abstract:[Objective] The response of soil aggregate stability and organic carbon before and after land reclamation using different land use types were analyzed in order to provide a scientific theoretical basis for wasteland reclamation, vegetation restoration, and agricultural production in the Ebinur Lake Wetland Reserve.[Methods] Five different land use types in the Ebinur Lake basin of Xinjiang were evaluated in this study:uncultivated natural forest land (CK), cultivated artificially planted lycium land, vitis land, cotton land, and alfalfa land. These land use types were selected to determine the response of soil structure and organic carbon content after land cultivation in a desert ecosystem.[Results] Land cultivation had significant effects on soil aggregate stability and carbon fixation in a desert area. After land cultivation, the content of macro aggregates (>0.25 mm) and the stability of aggregates of cultivated lands were significantly greater than those of CK. Cotton land had the highest content of force-stabilized macro aggregates (>87%). Lycium land had the highest content of water-stabilized macro aggregates (>79.7%). Different artificial tillage practices increased the content of macro aggregates. The particle size organic carbon contents in the aggregates of cultivated lands in the 0-30 cm soil layer were 5.91-15.46, 5.50-10.70, 8.12-16.11, and 6.90-13.67 g/kg, respectively. These values were significantly greater than the contents observed for CK (3.91-8.73 g/kg), mainly distributed in the 0.25-0.5 mm particle size. The organic carbon contents of soil aggregates increased significantly under all artificial land use practices, and the lycium land organic carbon content increased most significantly.[Conclusion] The cultivation practice of planting lycium barbarum after land cultivation was more conducive to increasing soil aggregate stability and improving organic carbon fixation than the other cultivation practices. Land cultivation can significantly increase soil carbon sequestration capacity and improve soil structure.

Abstract:[Objective] The spatial correlation characteristics of the amount and intensity of carbon emissions resulting from cultivated land utilization in an urban agglomeration in the middle reaches of the Yangtze River were analyzed in order to provide theoretical and practical guidance for achieving regional high-quality development.[Methods] The IPCC coefficient method, the overall coupling analysis model, and the bivariate spatial autocorrelation method were used in this study.[Results] ① The amount of carbon emissions resulting from cultivated land utilization in the study area showed a significant upward trend during 2010-2013, with an average annual growth rate of 2.0%. Carbon emissions showed a downward trend during 2014-2020, with an average annual decline of -2.6%. During the study period, the difference between the carbon emissions of each city tended to expand. ② The intensity of carbon emissions resulting from cultivated land utilization in the study area showed a fluctuating downward trend, with an average annual decline of -4.9%. However, due to the marginal decline effect, it was increasingly difficult to further improve the carbon emission intensity. ③ During the study period, the center-weighted distance between the amount and intensity of carbon emissions resulting from cultivated land utilization in the study area decreased from 0.571 km to 0.312 km. The included angle between their moving directions also showed a general declining trend, and the coupling situation continued to strengthen. ④ From 2010 to 2020, there was a significant spatial positive correlation between the amount and intensity of carbon emissions resulting from cultivated land utilization in the study area, and there was also spatial heterogeneity in this effect. The agglomeration situation was mainly manifested in the "high-high" and "low-low" area, which was represented by the Wuhan urban agglomeration and the Changsha-Zhuzhou-Xiangtan urban agglomeration, respectively.[Conclusion] Different regulation measures should be taken according to the spatial correlation pattern between the amount and intensity of carbon emissions resulting from cultivated land utilization. The "dual control" mechanism for the amount and intensity of carbon emissions resulting from cultivated land utilization is also an important consideration.

Abstract:[Objective] The distribution of soil aggregates and the characteristics of organic carbon content were analyzed to determine the influence of biological crust on slope stability and nutrient retention in order to provide a reference and guidance for the application of biological crusts in slope restoration engineering.[Methods] Taking a restoration slope with vegetation concrete substrates as an example, the soil dry screening method and the soil wet screening method were used to study aggregates in the crust (0-2 cm) and subsurface layer (2-7 cm) and organic carbon characteristics of crust-covered and non-crust-covered slope soil.[Results] ① The presence of biological crusts significantly affected the distribution of soil aggregates, mechanical stability, and R_0.25 content. Compared with the check treatment (CK, no crust-covered slope), the stability index of the crust covering layer increased by 27.42%-33.51% (MWD) and 21.66%-28.88% (GMD), and the content of large aggregates (R_0.25) increased by 10.68%. Moss crust had the most significant impact. ② Soil aggregate particle size of different crust types measured by the wet sieving method were mainly>0.25 mm. The water stability parameters MWD, GMD, and R_0.25 of the crust-covered slopes were between 1.93 and 5.33 mm, 0.85 and 3.16 mm, and 70.97% and 87.50%, with moss-covered slopes having the largest values. The D_d values were between 2.48 and 2.74, with the smallest values observed for moss-covered slopes. The water stability of aggregates was best for moss-covered slopes and worst for bare slopes. ③ The presence of crust promoted the accumulation of organic carbon in the soil, and the organic carbon content was more than twice that of the CK treatment. The effect on the organic carbon level for the surface soil was obvious, and the effect for the subsurface soil layer was low. ④ There was a significant positive correlation between soil organic carbon content and soil water stability parameters MWD, GMD, and R_0.25 (p<0.05). The level of organic carbon and the stability of aggregates were closely related and affected each other. Increasing organic carbon level played an important role in increasing aggregate stability.[Conclusion] The existence of a biological crust increases aggregate stability and organic carbon accumulation of repaired slopes. The crust has a certain effect on the stability of the ecologically repaired slope and on nutrient fixation. The strength of different crust types varies, with moss and mixed crusts having the best soil fixation and carbon sequestration effects.

Abstract:[Objective] The land use carbon emissions were measured, the decoupling relationship between land use and carbon emissions were determined, and the carbon emission pattern of land use change was revealed in order to provide a scientific basis for the formulation of resource protection and ecological civilization policies.[Methods] The study was conducted in Henan Province, a typical agricultural production center in China having a large population. The evolution characteristics of spatial and temporal patterns of land use carbon emissions and land use intensity at the county scale were determined based on remote sensing monitoring data of the current land use situation during the past 20 years. The decoupling relationship between land use intensity and carbon emissions was determined with the help of a theoretical framework of decoupling analysis.[Results] ① Carbon emissions during the study period showed obvious spatial heterogeneity. Carbon emission levels in central and Northern Henan Province were significantly greater than in other regions. Carbon emissions in the plain areas and areas around large cities were significantly greater than in mountainous and hilly areas. ② Land use intensity continued to increase during the study period, and land use intensity in the central region of Henan Province was significantly greater than in the southern region. The distribution of land use intensity in the northern region of Henan Province showed obvious spatial clustering. ③ The relationship between land use intensity and carbon emissions during the study period was mainly characterized as either expansion negative decoupling and strong decoupling. It is necessary to continuously shift from the double-high model of high resource consumption and high carbon emissions to the low-carbon development model of low resource consumption and low carbon emissions.[Conclusion] There were obvious differences in the degree of decoupling between land use intensity and carbon emissions at different stages and in different regions. Therefore, different control policies should be adopted to promote a coordinated and stable development relationship between ecological environmental protection and economic development.