Abstract:[Objective] The morphological characteristics and influencing factors of a gully head in a typical agricultural watershed in the rolling-hill black soil region of Northeast China were studied in order to provide basic data and theoretical support for controlling gully erosion in a mollisols region. [Methods] The study was conducted for gully heads of a typical agricultural watershed in Hainan Township, Hailun City, Heilongjiang Province. The morphological characteristics of the gully heads, soil type, and soil configuration were investigated in the field. The correlation between gully heads morphological characteristics and internal causes (soil characteristics) and external environmental factors were analyzed. [Results] ① At Hainan Township small watered the soil types of the cut gully head were typical black soil, meadow black soil, and alluvial soil. The soil structure consisted of mainly humus layer (A) + illuvial layer (B) + parent material layer (C) type, supplemented by humus layer (A) + parent material layer (C) type and humus layer (A) + parent material layer (C) + buried layer (Ab) type. ② Correlation analysis showed gully morphology was complicated by internal and external factors, and the single morphology was affected not only by internal and external factors, but also by its own morphology. ③ Redundancy analysis showed that the slope, soil configuration, and catchment area of the gully head were the main factors affecting gully head morphology, and were positively correlated with gully head morphology. The vegetation coverage of the gully head, the distance between crops and the gully head, the angle between the ridge and the gully head elevation were negatively correlated with gully head morphology. [Conclusion] The morphological characteristics of gully heads are complex, and the soil vertical difference is the fundamental internal factor. Gully head morphology is affected by both internal and external factors.

Abstract:[Objective] The hydrological and ecological traits, and the water-holding characteristics of a forest after stand reconstruction were analyzed in order to provide a reference for ecological management, vegetation restoration, and tree species allocation in red soil erosion areas in Southern China. [Methods] This study was conducted at an Aleurites montana stand that was established after pine forest reconstruction in an erosion area of Changting County, Fujian Province. Differences in litterfall water retention indicators were compared between the A. montana stand and a grassy slope (CK). The soil physical properties of the 0—60 cm soil layer under the A. montana stand were measured, and the water retention performance of the stand was comprehensively evaluated by the subordinate function method. [Results] The water retention of the litter in the A. montana stand was always higher than that of CK, which was 1.15 times the value of CK before immersion and 2.10 times the value of CK after immersion for 24 hours. The water absorption rates of the litter in the A. montana stand and CK were 1 723.64 and 700.8 mm/h, respectively, after immersion for 0.25 h. The cumulative amount, maximum water-holding capacity, and effective storage amount of litter in the A. montana stand were significantly higher than those in CK. The soil bulk density of the 0—10 cm soil layer was significantly lower than that of other soil layers, while the maximum water-holding capacity, capillary water-holding capacity, field water-holding capacity, capillary porosity, and total porosity were significantly higher than those of other soil layers. The soil effective water storage and effective water reserve were significantly lower in the 0—20 cm layer than in the 20—60 cm layer. The comprehensive evaluation of the stand showed that the evaluation value of soil capillary porosity was higher, while that of soil natural moisture content was lower among all the indicators. [Conclusion] The A. montana stand had high water-holding capacity in the litter, as well as favorable aeration and water permeability characteristics in the soil. The comprehensive evaluation of the A. montana stand suggested that soil porosity, especially capillary porosity, played an important role in improving the water-holding performance of the stand.

Abstract:[Objective] The effects of different irrigation methods and irrigation amounts on soil water, soil salt changes, and oat growth characteristics were explored to provide a scientific reference for improving crop production efficiency and soil water management in saline-alkali land. [Methods] Pot experiments were conducted with three irrigation treatments: conventional irrigation, fixed unilateral root-zone irrigation (FURI), and alternate partial root-zone irrigation (APRI). Three irrigation amounts were evaluated: W₁ (60% θ_f—70% θ_f, θ_f is field water-holding capacity), W₂ (70% θ_f—80% θ_f), and W₃ (80% θ_f—90% θ_f). Conventional irrigation was used as the control. Therefore, there were a total of nine treatment combinations. [Results] ① Under the different irrigation treatments, the change trend of water content in each soil layer was basically the same. As irrigation amount increased, the effect of salt leaching was more significant. The deep water content of conventional irrigation was generally higher than that of the other two irrigation treatments. ② Plant height, relative chlorophyll content of leaves, and oat quality increased with increasiong irrigation amount. The contents of crude fat, crude protein, and β-glucan in oat were 7.02%, 3.76%, and 6.06%, respectively, greater under the W₂ irrigation level than under the conventional irrigation level, but the SPAD values of oat leaves were lower under W₂, which affected the photosynthetic capacity of oat. ③ Soil salinity showed different degrees of accumulation as oat growth progressed, and the salt accumulation rate with alternate partial root-zone irrigation was the lowest. At the same time, soil salinity had a significant effect on oat root growth, water use efficiency, and yield. Total root length, total root surface area, and total root volume increased by 6.75%, 6.92%, and 12.5%, respectively. Water use efficiency increased by 17.32% compared with conventional irrigation with the same irrigation amount (W₂). [Conclusion] The medium irrigation amount (W₂) under alternate partial root-zone irrigation was beneficial for improving the production efficiency of oat and was better at controlling salt accumulation.

Abstract:[Objective] Maximum flood peak flow is the decisive factor leading to flood disaster. The correlation between precipitation frequency, management level, and flood peak flow and flood disaster loss in a small watershed was studied to provide a scientific basis for soil and water conservation, disaster reduction, and prevention. [Methods] The water transfer benefits of soil and water conservation measures in two adjacent basins of Caijiamiao and Yehugou from 1981 to 2022 were analyzed by using both regression analysis and comparative analysis, as well as the effects of precipitation factors and soil and water conservation measures on flood peak flow. [Results] ① The benefit of water conservation measures in a small watershed increased with increasing management level, and decreased with increasing precipitation frequency. ② Annual maximum daily precipitation had a highly significant positive effect on the change of flood peak flow (p＜0.01), and the contribution rate coefficient was 0.707. Management level had a negative impact on the flood peak flow, and the contribution rate coefficient was -0.237. ③ The disaster loss intensity of 30-year flood peak flow (frequency of 3%) and 50-year flood peak flow (frequency of 2%) reached 1.74×10⁵ yuan/km² and 3.13×10⁶ yuan/km², respectively, with the latter value being 16.95 times greater than the former value. [Conclusion] The main factor affecting the change of flood peak flow was the annual maximum daily precipitation. Soil and water conservation measures had a significant impact on the reduction of flood peak flow. The higher the degree of watershed management, the more obvious the effect of reducing flood peak flow, and the greater the ability to reduce the economic loss of flood disasters.

Abstract:[Objective] Dust retention of typical shrublands in a desert-oasis ecotone was quantified, in order to provide a basis for the evaluation of dust retention benefits of regional windbreak and sand-fixing tree species and the construction of oasis protection systems. [Methods] Field investigations and sampling, indoor washing filtration, and other methods were used to determine the temporal and spatial variation characteristics of dust retention amount and particle size of three shrub species (Holoxylon ammodendron, Tamarix chinensis, and Nitraria tangutorum) in the desert-oasis transition zone along the 4-km range from desert to oasis in early March (winter state) and late June (summer state). [Results] The amount of dust retention gradually decreased from desert to oasis. In early March, the average decreases in dust retention of Haloxylon ammodendron, Tamarix chinensis, and Nitraria tangutorum were 20.74%, 16.13% and 14.72%, respectively. In late June, the average decreases were 14.37%, 9.23%, and 26.54%, respectively. In early March, Haloxylon ammodendron had the largest amount of dust retention, about 172.36 g/plant. In late June, Tamarix chinensis had the largest amount of dust retention, about 345.16 g/plant. In the first ten days of March, the dust particle size for the three shrubs mainly ranged from 20 to 50 μm, accounting for about 41.00% of the dust that was trapped. A small amount of dust trapped by Haloxylon ammodendron had particle sizes of 500 to 1000 μm, accounting for about 15.00% of the total. In late June, the particle size of the dust ranged from 100 to 200 μm, and a small amount ranged from 5 to 10 μm. [Conclusion] In March and June, the dust retention of the three shrubs showed a decreasing trend from desert to oasis. The dust retention and dust retention particle size of shrub plants were affected by time, space, and plant leaf surface characteristics.

Abstract:[Objective] The effects of a long-term Caragana korshinskii plantation on the stability of soil aggregates and erodibility on loess hilly slopes were determined, in order to provide theoretical support for artificial vegetation construction and ecological restoration in the Loess Plateau region. [Methods] A barren grassy slope was compared with C. korshinskii plots of different plantation ages (15, 25, 35 years) along similar slope contour lines. the characteristics of changes in soil aggregate stability and erodibility due to a long-term C. korshinskii plantation was analyzed, as well as the main influencing factors. [Results] ① The soil aggregate stability indicators 〔i.e., mean weight diameter (MWD), geometric mean diameter (GMD), and the content of aggregates ＞0.25 mm (WR_0.25)〕 generally followed the order of 15-year C. korshinskii plantation ＞ barren grassy land ＞ 25-year C. korshinskii plantation ＞ 35-year C. korshinskii plantation. In terms of slope position, the order was bottom slope ＞ top slope ＞ mid-slope ＞ upper slope. Conversely, the soil erodibility K factor exhibited an opposite trend. ② As C. korshinskii plantation age increased compared with barren grassy land, soil aggregate stability indicators initially increased and then decreased, while the stability of barren grassy strips continuously declined. The difference between the two became more pronounced after plantation age exceeded 15 years, especially at the bottom slope. ③ Soil organic carbon and slope position were the main factors influencing soil aggregation stability and erodibility on the slope, explaining 38% and 4.1% of the variation, respectively, followed by plantation age and altitude. [Conclusion] Strip planting of C. korshinskii on loess hilly slopes affected the distribution of soil organic carbon, thereby influencing soil aggregate stability and erodibility. Plantations of less than 15 years contributed to an increase in soil aggregate stability and a reduction in erodibility, but a reverse trend gradually emerged with older plantations, particularly at the bottom slope locations.

Abstract:[Objective] The annual runoff changes and leading factors in Qingshuihe River basin and Baihe River basin were comprehensively analyzed, and the actual runoff changes and influencing factors in the two river basins were further revealed, in order to provide theoretical basis for water resources planning and management in Zhangjiakou region. [Methods] Based on Budyko model, the study was conducted for the Qingshui River basin in the upper reaches of the Yongding River and the Baihe River basin in the upper reaches of the Chaobai River. Coupled water-heat balance equations for the basins were constructed. Sensitivity coefficients of potential evapotranspiration to major meteorological factors were accurately calculated, and then elasticity coefficients of runoff to major meteorological factors from the sensitivity coefficients were calculated. Finally, the contributions of climate change and human activities to runoff changes were calculated. [Results] ① The elasticity coefficients of meteorological factors in the Qingshui River basin and the Baihe River basin showed increasing trends in recent years, indicating that the increasing climate-hydrology coupling in these two basins and the hydrological processes in the Qingshui River basin were more sensitive to climate change than the coupling and processes in the Baihe River basin. ② Human activities dominated changes in the runoff of the Qingshui River basin and the Baihe River basin. The contribution rates of human activities to runoff changes in the Qingshui River basin and the Baihe River basin were 65.37% and 83.90%, respectively. ③ Compared with the Fu, Choudhury-Yang, and Wang-Tang formulas, the Zhang formula had better applicability in Qingshui River basin and the Baihe River basin. Actual evapotranspiration from the basins was modeled better, with the R² value reaching 0.97. [Conclusion] The contribution of human activities to runoff changes in the study area ranged from 65.37% to 83.90%, and the contribution of climatic factors ranged from 16.10% to 34.63%. In the future, the impact of climate and human activities should be considered at the same time. Continued efforts should be made to strengthen research on the mechanisms and processes of runoff and evapotranspiration in water limited environments, therefore to ensure the security of water resources.

Abstract:[Objective] The effects of Tetraena mongolica shrub decline on the nutrient and sedimentary characteristics of nebkhas in the West Ordos National Nature Reserve were determined, in order to provide a theoretical basis for the study of shrub decline and the nutrient accumulation effect of nebkhas in arid desert areas. [Methods] Taking Tetraena mongolica shrubland as a study area, soil samples from Tetraena mongolica shrubland areas with different degrees of shrub decline were collected, and the effects of shrub decline on sand piles were determined by analyzing the grain size of surface sediments and nutrient characteristics of sand piles. [Results] ① The surface sediments of the sand piles of the Tetraena mongolica shrub in the Ordos National Nature Reserve were mainly fine sand. The fine sand content of the surface sediments of the Tetraena mongolica shrub in each decline degree exceeding 60%. With decreasing shrub decline, the content of fine sand and coarse sand in shrub surface sediments increased. The grain size of the surface sediment of the sand pile of the Tetraena mongolica shrub was approximately a single peak, and the peak particle size was between 15.07 and 447.95 μm. The bare sandy land showed obvious double peaks at 12.35—494.94 μm and at 546.86—1482.94 μm. ② There were significant differences (p<0.05) in soil nutrient content between the sand dunes and the interdune space (areas with Tetraena mongolica shrub decline greater than 60% had higher nutrient content). ③ The nutrient content of sand piles in Tetraena mongolica shrubland was significantly higher than that in interdune open space, which had a positive effect on nutrient accumulation, and there was a “fertilizer island” effect. The enrichment ability of AN was the strongest, and the enrichment ability of SOM was the weakest. Except for Tetraena mongolica shrublands with decline degrees between 30% and 60%, the recession degree of other Tetraena mongolica shrublands on the sand nutrient enrichment effect difference was not obvious. [Conclusion] On the whole, the greater the decay degree of the sand pile in the study area, the smaller the content of fine sand and coarse sand in the surface sediment, and the higher the nutrient content under it.

Abstract:[Objective] The tensile and flexion mechanical properties and stress-strain characteristics of roots of Pinus massoniana were studied to enrich the mechanical properties of tree roots, in order to provide a reference for soil stabilization and soil erosion prevention in planting areas of Pinus massoniana. [Methods] The 0—1, 1—2, 2—3, 3—4 and >4 mm root diameter roots of Pinus massoniana were taken as the research object. STS5000 universal tensile machine was used to conduct single root test to analyze the tensile and flexion mechanical properties and stress-strain characteristics of different root diameter roots of Pinus massoniana. [Results] Both the tensile strength and flexural strength of a single root of Pinus massoniana increased with increasing root diameter in accordance with the polynomial relationship of y=ax³+bx²+cx+d, having respective R² values of 0.91 and 0.69. Both the tensile strength and flexural strength decreased with the increasing root diameter according to y=ax^-b, having respective R² values of 0.50 and 0.35. The root tensile elongation rate increased with increasing root diameter according to the equation y=ax³+bx²+cx+d (R²=0.17), while the root flexural elongation rate had no significant correlation with increasing root diameter. Both the tensile elastic modulus and flexural elastic modulus of the root system decreased with increasing root diameter according to y=ax³+bx²+cx+d, having respective R² values of 0.22 and 0.18. The root tensile and flexural stress-strain curves of Pinus massoniana showed four stages: elastic deformation, elastic-plastic deformation, strain hardening, and peripheral (fracture) failure. The tensile stress-strain curve generally showed an “upward convex” shape, while the bending stress-strain curve generally showed a “downward concave” shape. The tensile and flexural fracture stages were divided into peripheral fracture and overall fracture modes, both of which were influenced by the peripheral and vascular tissues and had two types of fracture. [Conclusion] The flexural mechanical properties of the root system of Pinus massoniana with a root diameter of <3 mm were superior to the tensile mechanical properties, while the tensile mechanical properties of roots with diameters of >3 mm were superior to the flexural mechanical properties. Planting Pinus massoniana in slope areas can effectively increase soil erosion resistance.

Abstract:[Objective] The shield-shaped movable sand barrier is a new type of sand fixation barrier. The barrier is made according to bionic principles and composed of a shield-shaped iron mesh screen supporting the stems and leaves of the sand fixation shrub, Oxytropis aciphylla. The sand fixation effects of shield-shaped movable sand barriers were determined to choose the optimized type of sand fixation barrier to reveal the wind break and sand fixation mechanisms of shield sand barriers, in order to provide theoretical references for the selection and formulation of sand control measures in field projects. [Methods] A wind tunnel simulation experiment was conducted. The wind speed and flow field of the shield-shaped sand fixation barrier were measured at four wind speeds of 6, 10, 14, and 18 m/s. The wind erosion experiments were conducted on the sand fixation barriers at three wind speeds of 10, 14, and 18 m/s. Comparative analysis was conducted on the windbreak and sand fixation effects of in-situ natural and different size bionic barriers. [Results] ① When the airflow passed through the shield-shaped movable sand fixation barrier, its velocity weakened, forming a significant deceleration zone. At 6 m/s, the deceleration settlement zone reached 20 H (H means the height of barriers, H=11 cm ). As wind speed increased, the deceleration settlement zone decreased. At 10 and 14 m/s wind speed, the deceleration settlement zone was 15 H. At 18 m/s wind speed, the barrier also maintained a deceleration settlement zone of 15 H. ② Under the three wind speeds, the average sediment transport capacity of the new type of shield-shaped movable sand fixation barrier was 13.8% (10 m/s wind speed), 21.1% (14 m/s wind speed), and 23.4% (18 m/s wind speed) of the sediment transport capacity without sand barriers. [Conclusion] The shield-shaped movable sand fixation barrier with a complete structure and a largest diameter had the best wind and sand prevention effect. The shield-shaped movable bionic sand fixation barrier had good wind and sand prevention effects, and can be moved, combined, and mechanically woven. It has a broad application potential in the field of desertification prevention, and wind and sand fixation.

Abstract:[Objective] The characteristics of “non-grain conservation” farmland, and the supply and demand situation of farmland and the influencing factors of “non-grain conservation” farmland in Kashgar region were determined, in order to propose regulatory countermeasures and suggestions. The study was conducted from the perspective of food security. [Methods] The spatial-temporal characteristics of “non-grain conservation” cultivated land were determined. The profit and loss of cultivated land supply and demand and the safe interval of“non-grain conservation” cultivated land in Kashgar region were determined from 1995 to 2020 based on field investigation and statistical data using the grain supply and demand balance method. An indicator system for the influencing factors of “non-grain conservation” farmland was constructed, and a binary Logistic regression model was used to analyze the degree of influence of each influencing factor on “non-grain conservation” farmland. [Results] ① From 1995 to 2020, the spatial-temporal evolution trend of the “non-grain conservation” rate and “non-grain conservation” region of cultivated land in Kashgar region was almost the same, and exhibited a fluctuating upward trend from 1995 to 2014, and a fluctuating downward trend after 2014. The spatial evolution characteristics showed a distribution pattern of higher in the northeast, and lower in the southwest and northwest. ② During the study period, only Kashgar City was in a long-term deficit of cultivated land supply. Ta County experienced a deficit of cultivated land supply in 2010, and other counties and cities experienced a surplus of cultivated land supply. The “non-grain conversion” rate of cultivated land in Kashgar City had seriously exceeded the safe range, and the rest of the Kashgar region was within the safe range. ③ The influence of family agricultural labor force, the degree of concurrent employment of farmers, the change of agricultural resource price, and the effect of grain subsidy policy on “non-grain conservation” cultivated land was significant, while the other influencing factors had no significant influence on “non-grain conservation” cultivated land. [Conclusion] The level of “non-grain conservation” farmland in the Kashgar region was high, and the supply of farmland was unbalanced. It will be necessary to improve the protection policy of regional farmland, formulate differentiated management strategies, and curb the spread of “non-grain conservation” farmland, therefore to realize the sustainable development goal of food security and farmland security.

Abstract:[Objective] The effective promotion of ecological compensation policies will play an important role in ecological and environmental protection and high-quality development of the Yellow River basin. The sorting and scientific evaluation of ecological compensation policies in the Yellow River basin were conducted to further optimize and improve ecological compensation policies. [Methods] Based on 170 ecological compensation policy texts promulgated by nine provinces (districts) in the Yellow River basin from 2001 to 2022, a social network graph and quantitative evaluation index system of ecological compensation policies were implemented using the data analysis software ROSTCM and the policy modeling consistency (PMC) index model. Nine ecological compensation policies served as research objects. Text mining and content analysis methods were used to evaluate each dimension of the selected policies through the PMC index measurement, the depression index calculation, and PMC surface drawing. [Results] The overall quality of the nine ecological compensation policies evaluated in the Yellow River basin proved to be higher. Six of the evaluation results were excellent, and three were good. All nine policies scored high in terms of policy nature, policy measures, policy evaluation, and policy guarantee, but scored lower in policy design, policy objectives, and policy content. [Conclusion] The design and content of ecological compensation policies in the Yellow River basin need to be improved, and the important role of policy objectives in ecological governance has been overlooked. Further optimization should be made in terms of formulating a policy plan that combines long and short periods, exploring diversified compensation methods, and increasing attention to both compensation standards and fund supervision.

Abstract:[Objective] Resource-based cities are important guaranteed cities for national resource and energy security. Their transformation and development mode should be promoted in the direction of high quality. The change of land use structure under the background of transformation of resource-based cities was studied and the prediction and simulation were carried out to provide new ideas for the territorial space optimization of resource-based cities in the new era. [Methods] Based on the concept and connotation of the transformation and development of resource-based cities, the systematic impacts of five dimensions of economy, society, population, science and technology, resources and environment are analyzed, and correlated with spatial layout, a system dynamics model was built. Historical data for Tongling City, Anhui Province from 2005 to 2020 was used as a reference, and datasets from 2021 to 2035 were used in a simulation scenario to carry out a multi-contextual land use structure trend prediction analysis. [Results] ① The current situation of land use and economic development in Tongling City laid the foundation for development that was used as the basis of setting the conditions for transformation and reasonable prediction of changes in land use structure. ② As a systemic concept, the transformational development of resource cities has formed a hierarchical framework of “system-indicator-element”, which is not only interrelated and inextricably linked, but also transmits its effects on different land types and influences the land-use system. ③ Differences in the development of land use trends between 2021 and 2035 in Tongling City were similar, i. e., the decrease of arable land, forest land, water area, grassland, and unused land decreased from economic development, social progress, and comprehensive development, and the area increased slightly under the scenario of resource and environmental protection. In contrast, the increase rate of construction land decreased with economic development, social progress and comprehensive development, and the expansion rate was controlled to a certain extent under the scenario of resource and environmental protection. [Conclusion] The new-era transformation of resource-based cities should not only integrate the intrinsic elements into a systematic concept but also enhance the attention of the land-use system and emphasize structural rationality and development coordination.

Abstract:[Objective] The landscape ecological pattern of the Jialing River basin was analyzed to enhance ecosystem service functions and stabilize the ecosystem to reduce ecological risks, thereby providing a scientific basis for promoting regional sustainable development. [Methods] The study was conducted for the Jialing River basin, an important ecological barrier in the upper reaches of the Yangtze River. The dynamic equivalent ecological service value model (ESV) evaluation results were used to identify ecological sources based on the optimal spatial scale of the ecological risk index model (ERI) evaluation results to determine the ecological resistance surface. These results were combined with the minimal cumulative resistance model (MCR) to extract an ecological corridor construction landscape network. [Results] ① From 2005 to 2020, ESV in the Jialing River basin was high in the north and low in the south, with a fluctuating growth trend. In total, ecosystem service value increased by 2.10×10¹⁰ yuan, and the contribution rate of woodland was the highest (50%), with contribution rates of 25% for grassland and 14% for farmland. ② The particle size and amplitude for suitable analysis in the Jialing River basin were 150 m and 750 m, respectively. From 2005 to 2020, ERI showed a pattern of higher in the northwest and lower in the central and south, with a decreasing trend over time. ③ The entire ecological network distribution presented a northwest-southeast direction. Eleven ecological sources were identified, with a total area of 36 297.19 km², 365 potential ecological corridors, and 133 ecological nodes. Among them, there were 47 important ecological corridors and 39 important ecological nodes. ④ Key ecological protection areas should be constructed as new ecological sources, and development in the Jialing River basin should be restricted. There are six road-type ecological corridors, three green-type ecological corridors, 13 river-type ecological corridors, and 24 ecological nodes were identified. [Conclusion] After optimization, the ecological network density of the Jialing River basin increased, running through the full range of ecological sources, and the overall connectivity was improved. These results could provide new ideas for the pattern of ecological watershed restoration, and strategies for ecological protection and sustainable development.

Abstract:[Objective] Net primary production (NPP) of vegetation at the Dongtan wetland in Chongming District, Shanghai City was estimated, and methods for NPP estimation in small-scale wetland areas were determined, in order to provide data support for the effective assessment of carbon sequestration capacity in wetland ecosystems. [Methods] The study focused on Dongtan wetland, and used Sentinel-2B satellite remote sensing data and ground-based meteorological data. Monthly, seasonal, and annual-scale NPP estimates were made for 2017—2021 using the CASA model. Correlation analyses were performed to examine natural factors influencing the spatial-temporal variation in NPP. [Results] ① Mean NPP values (calculated by C) for the study area from 2017 to 2021 were 390.22±155.68, 426.74±102.40, 575.25±445.51, 539.29±201.87 and 611.81±464.88 g/(m²·yr), respectively, with total amounts (calculated by C) of 1.56×10¹⁰, 1.96×10¹⁰, 2.54×10¹⁰, 2.70×10¹⁰, and 2.94×10¹⁰ g/yr, showing a clear increasing trend. ② High NPP areas continuously expanded towards the sea, with Phragmites australis accounting for 54.73%—70.03% of the total NPP in the study area, followed by Spartina alterniflora and Scirpus mariqueter. ③ Monthly mean NPP values exhibited a normal distribution, and NPP values showed significant spatial variations with the seasons. Average NPP values and total NPP were notably higher in summer and autumn, with less pronounced changes in spring and winter. [Conclusion] Monthly average temperature was identified as the primary factor influencing monthly mean NPP values. The wetland vegetation classification results was obtained by using high spatial resolution remote sensing images， the authenticity of estimation results could be improved by localizing estimation model parameters.

Abstract:[Objective] A landscape ecological risk assessment for Xiangjiang River basin were conducted, and an ecological security pattern were established, in order to provide guidance for the implementation of regional ecological conservation and restoration efforts in the area. [Methods] Eleven indicators were selected from the three perspectives of natural environment, human society, and landscape pattern to construct Xiangjiang River basin landscape ecological risk evaluation indicator system. Based on this system, spatial principal component analysis was applied to evaluate the landscape ecological risk, and then, a comprehensive ecological resistance surface was constructed. The InVEST model, morphological spatial pattern analysis, and landscape connectivity analysis were combined to identify ecological sources. Circuit theory was then applied to identify ecological corridors, ecological pinch points, and barrier points area. [Results] ① Human society had the greatest impact on the landscape ecological risk of Xiangjiang River basin. Areas of high landscape ecological risk extended outward from multiple high-value centers located in urban agglomerations and various prefecture-level cities, while areas of low landscape ecological risk were primarily located in the southeastern and southern forest regions. ② A total of 32 ecological sources were identified, covering an area of 20 415.89 km², accounting for 22% of the total basin area, and 64 ecological corridors were identified with a total length of 1 888.25 km. 50 ecological pinch points and 41 ecological barrier points were identified, accounting for 0.8% and 0.6% of the total basin area. ③ Ecological protection areas, ecological improvement areas, ecological restoration areas, and critical ecological areas were delineated, with different ecological protection and optimization measures formulated. [Conclusion] Rationalizing ecological security patterns is crucial for the sustainable development of the eco-economy. Based on a landscape ecological risk analysis of Xiangjiang River basin, corresponding measures and policies should be adopted for ecological source areas, ecological corridors, and key nodes to carry out ecological restoration and protection to maintain ecological security.

Abstract:[Objective] An improved remote sensing ecological index model suitable for high vegetation area was constructed to better monitor and evaluate the ecological quality of hilly areas, and the influencing factors of ecological quality were explored, in order to provide scientific support for the balance between development and ecology at Taojiang County, Yiyang City, Hunan Province. [Methods] To address the saturation limitations of the normalized difference vegetation index (NDVI) in densely vegetated areas, the improved remote sensing ecological index (MRSEI) was used to quantify the temporal variation in the ecological environment quality of Taojiang County from 2000 to 2021. Additionally, a geographic detector model with optimized parameters was utilized to analyze the driving forces behind six influencing factors, including vegetation coverage, precipitation, temperature, land use, elevation, and population density. [Results] ① Compared with the RSEI model, the MRSEI model more effectively addressed the issue of NDVI saturation in areas with high vegetation cover, enabling a more precise monitoring of the ecological environment in Taojiang County. ② The average RSEI values for the five periods from 2000 to 2021 in the study area were 0.77, 0.84, 0.83, 0.75, and 0.79, respectively, indicating a satisfactory performance in ecological environmental quality with a trend of improvement-deterioration-improvement. ③ From the analysis of the factors influencing ecological environmental quality, land use emerged as a key determining factor in the study area. In the interactive factor detection analysis, the interaction between land use and elevation was the strongest. [Conclusion] The improved RSEI model could accurately evaluate the eco-environmental quality in high-vegetation areas. The eco-environmental quality of Taojiang County was generally at a good level and showed an upward trend from 2000 to 2021. The change of eco-environmental quality was mainly affected by both natural and human factors.

Abstract:[Objective] The spatial differentiation characteristics of the ecological value of cultivated land in river basins and regions within river basins were clarified, and a differential calculation model of the ecological compensation standard for cultivated land was established to improve the ecological compensation mechanism for cultivated land protection, in order to provide a reference for the formulation and implementation of ecological compensation policies for cultivated land protection in river basins. [Methods] The payers and beneficiaries of ecological compensation for cultivated land was defined, and the spatial differences in the ecological value of cultivated land in Liaohe River basin in Jilin Province were analyzed. On this basis, the ecological spillover benefits and boundaries of cultivated land were measured. Based on key factors such as regional cultivated land resource endowment and socio-economic development stage, a differentiated ecological compensation standard calculation model for cultivated land was established, and the ecological compensation standards and quotas for cultivated land in the research area were formulated. [Results] ① In 2020, there was an overall ecological surplus in the cultivated land of the research area, which belongs to the ecological compensation area. Except for Tiexi District, Longshan District, and Xi’an District, which belong to the cultivated land ecological payment area, the sustainability of cultivated land ecological services in other areas was good, and they had a strong carrying effect on the ecological consumption of cultivated land in the region, all of which belong to the cultivated land ecological compensation area. ② The cultivated land in the research area had an important ecological value, and its spatial differences were significant. The ecological spillover value of cultivated land reached 8.732 billion yuan, providing important ecological products and services for other regions, among which Gongzhuling City and Lishu County were the main areas of ecological spillover value of cultivated land. ③ The ecological compensation standard for cultivated land in the research area was 5 191.16 yuan/ha, with a total compensation amount of 5.976 billion yuan. Due to differences in ecological value, ecological profit and loss area, protection responsibility, and development stage of cultivated land, there were significant differences in compensation standards and amounts among different regions. [Conclusion] The research results scientifically identified the relevant stakeholders of ecological compensation for cultivated land and determined the ecological spillover benefits of cultivated land while considering spatial scale and regional reality, thereby achieving differentiated ecological compensation for cultivated land. The significance of the study is that it improves the mechanism of ecological compensation for cultivated land and enhances ecological compensation.

Abstract:[Objective] The health level of ecosystems in Gansu section of the Yellow River basin was evaluated, in order to provide a theoretical reference and decision-making basis for the ecological protection and high-quality development of the river basin. [Methods] Based on panel data from 2011 to 2021, the PSR model was used to build an ecosystem health evaluation index system in Gansu section of the Yellow River basin. The entropy method, comprehensive index method, and GM-ARIMA prediction model were used to comprehensively evaluate and predict the health level of ecosystems in the river basin. [Results] ① From 2011 to 2021, the comprehensive index of urban and state ecosystems showed an upward trend. In the important water supply ecological functional area of Gannan Yellow River, the health level of the Gannan ecosystem was “inferior”, and the health level of the Linxia ecosystem had changed from “inferior” to “poor”. In the Loess Plateau, the health level of the Lanzhou ecosystem had changed from “medium” to “good”, and the health level of the Tianshui, Dingxi, and Pingliang ecosystems had changed from “inferior” to “poor”. The health level of Baiyin and Qingyang ecosystems was “inferior”. In the sandstorm comprehensive preventions and control area, the health level of the Wuwei ecosystem was “inferior”. ② The comprehensive ecological environmental index from 2022 to 2031 is predicted to increase, but the ecosystem health level will not change significantly. [Conclusion] The overall health level of ecosystems in the Gansu section of the Yellow River basin is not high. Current ecological protection and environmental improvement measures have not fully solved the challenges faced by the ecological environment in the region. In the future, it will be necessary to further strengthen supervision and management to improve the health level of ecosystems in the region.

Abstract:[Objective] The effects of ridge and furrow planting on crop water use efficiency (WUE) and yield were systematically evaluated, and the main driving factors that affect the yield increase effect of ridge and furrow planting were studied, in order to provide scientific basis and theoretical basis for the promotion and reasonable application of ridge and furrow planting in arid and semi-arid rainfed agricultural areas in Northern China. [Methods] Using flat cultivation as a control and ridge-furrow cultivation as the treatment, a systematic analysis was conducted of 68 published studies from 1980 to 2023. The Meta-analysis methods was utilized to quantitatively analyze the effects of three typical ratios of ridge width (R) to furrow (F) (the higher with R/F > 1; the medium with R/F=1; the lower with R/F < 1) on crop WUE and yield. The comprehensive impact of the main driving factors of ridge-furrow cultivation on crop WUE and yield was also investigated, with considering climatic factors (i.e., annual average precipitation, annual average temperature), soil factors (soil density, soil nutrients), and human management factors (fertilizer use, crop types). [Results] Compared with traditional flat cultivation, all three ridge-furrow ratios significantly increased crop WUE and yield, with significant differences observed among the different ratios. Under high, medium, and low ridge-furrow ratios, crop WUE was significantly increased by 34.9%, 27.48%, 32.4%, respectively, and yield was increased by 39.94%, 25.98%, 34.93%, respectively. The high R/F ratio (>1) was applicable in regions with an annual average rainfall of less than 400 mm and an annual average temperature of less than 8 ℃, while the low R/F ratio (<1) was more effective in increasing crop WUE and yield in regions with an annual average rainfall of more than 600 mm and an annual average temperature above 10 ℃. The high R/F ratio (>1) had a higher yield-increasing effect under conditions of low soil bulk density and high soil total nitrogen (TN) content, while the low R/F ratio (<1) was more suitable under conditions of high soil bulk density and low soil available nitrogen (AN) and available phosphorus (AP) content. Intensive fertilizer input significantly reduced the yield-increasing effect of ridge-furrow cultivation, whereas low fertilizer application rates (nitrogen fertilizer application rate of 0 to 150 kg/ha, phosphorus fertilizer application rate of 0 to 75 kg/ha) resulted in the most significant increases in crop WUE and yield. [Conclusion] The increase in crop WUE and yield due to different ridge-furrow ratios was influenced by a combination of climatic factors, soil factors, and human management factors. Ridge-furrow cultivation was more suitable under natural conditions of scarce rainfall and low soil fertility. Applying low amounts of chemical fertilizers can optimize the yield increase and water conservation benefits of ridge-furrow cultivation.

Abstract:[Objective] The spatiotemporal evolution characteristics and driving factors of land use in Tanzania from 2000 to 2020 were analyzed in order to provide a reference for the formulation of effective land use policy and cooperation in resource development and utilization between China and Tanzania. [Methods] Based on the global 30 m spatial resolution land cover dataset, the spatial and temporal evolution and driving factors of land use in Tanzania from 2000 to 2020 were analyzed by using a variety of land use indicators and GIS spatial analysis methods such as standard deviation ellipse analysis, hotspot analysis and geodetector. [Results] ① The land use dynamic degree in Tanzania decreased (with a significant decrease in the provinces of Zanzibar Islands), while land use diversity and land use degree increased. ② The spatial distribution of cultivated land, forest land, grassland, and artificial surface presented a “northwest-southeast” trend. The center of cultivated land was constantly shifting southward, and the development gap between the north and the south gradually narrowed. The spatial distribution of artificial surface varied greatly from east to west, and was the most dispersed. ③ Cultivated land increased and was more concentrated in the previous period, mainly in the central and western zones, while the growth rate decreased and became more dispersed. The concentration of forest land decreased in the previous period, with the most significant reduction in the central, western, and southern zones, and the decrease rate became less in the later period. The growth rate of artificial surface was relatively small in the previous period, and was mainly concentrated in the eastern coastal area, and the growth rage accelerated in the later period. ④ The degree and significance of the impact of natural environment and socio-economic factors on changes in different land use types varied. Natural factors had a greater impact on changes in cultivated land than social factors, while artificial surface changes were mainly influenced by socio-economic factors. [Conclusion] The evolution characteristics of different land use types in different areas of Tanzania varied. Faced with issues such as insufficient development of cultivated land, continuous reduction of forest land, and disorderly expansion of artificial surface, it will be necessary to formulate land use development policies tailored to local conditions to enhance the pertinence and feasibility of the policies.

Abstract:[Objective] The function evolution and ecological effects of productional-living-ecological space in scenic spots were explored, in order to provide reference and decision-making basis for the spatial function optimization and ecological environment protection of productional-living-ecological space of scenic spots in Guizhou Province. [Methods] The study was conducted for Guizhou Province as an example, and used land use status data from 2009 and 2021 to construct the productional-living-ecological space. The data were analyzed by combining the productional-living-ecological space spatial transfer matrix, ecological environmental quality index, and ecological contribution rate methods. [Results] ① From 2009 to 2021, scenic areas in Guizhou Province were mainly characterized by ecological space, with an increase in living and ecological space and a decrease in production space. ② During the research period, the overall ecological environmental quality of scenic areas in Guizhou Province increased from 0.59 to 0.61, showing a spatial pattern of “higher in the east and lower in the west”, with a significant increase in high-quality and higher quality areas, which was mainly related to a series of ecological protection and restoration engineering programs implemented in Guizhou Province in recent years, as well as carrying out work such as resource protection and forestry reform. ③ The ecological environmental quality of scenic areas in Guizhou Province has significantly improved from 2009 to 2021, mainly due to the conversion of agricultural production land and grassland ecological land to forest ecological land. [Conclusion] The ecological environment quality of scenic spots in Guizhou Province has been significantly improved. In the follow-up planning and management, it is suggested to strictly control the growth of construction land and strengthen the ecological environment advantages of scenic spots.

Abstract:[Objective] Soil erosion in the Yellow River basin of Gansu Province was quantitatively analyzed and its driving mechanism was discussed in order to provide reference for soil and water resource management in this area. [Methods] The revised universal soil loss equation (RUSLE) model was used to quantify regional soil erosion in the Yellow River basin of Gansu Province from 1980 to 2020. The Theil-Sen slope was used to test the interannual variation of soil erosion, while spatial statistics were applied to determine soil erosion intensity and distribution under different underlying conditions. Additionally, geographical detector methods were used to investigate the main driving factors of soil erosion. [Results] ① The average soil erosion modulus (A) was 37.38 t/(hm²·yr) in the Yellow River basin of Gansu Province from 1980 to 2020, featuring an overall erosive intensity below the moderate level, with an area ratio of 70% to the total. Regionally, most of the Gannan Plateau was dominated by the slight level of erosion and presented a decreasing trend of A value during the statistical period. Longzhong and Longdong Loess Plateau were dominated by the light and moderate level of erosion, and both showed increasing trends. ② In terms of the land use/cover types, the highest A value and the largest amount of erosive volume were both found in the arable land, while the lowest A value and the smallest amount of the erosive volume were found in wetlands and the closed forest, respectively. Specifically, affected by the area of the distribution, in the Gannan Plateau, greater soil erosion was observed in the grassland, while in the Longzhong and Longdong Loess Plateau, remarkable erosion amounts were found in the arable lands. Topographically, higher A value was mainly located in zones with an altitude below 1 000 m above sea level, or within a slope range of 10° to 20°. ③ Mechanically, soil erosion was controlled and influenced more by the topographical factor of slope in the Gannan and Longdong Plateau, while soil erosion was significantly affected by soil texture in the Longzhong Plateau. The driving factors for soil erosion were multi-dimensional in tributary basins of Yellow River in Gansu Province, and the explanatory power of factor interaction was stronger than the explanatory power of individual factors regarding the variation of A value in space. High-risk zones for soil erosion were generally located in the steep terrain areas with greater precipitation and sparse vegetation. [Conclusion] The causes of soil erosion are different due to climate change and various underlying conditions. Serious soil erosion problems exist in Longzhong and Longdong loess plateau in tributary basins of the Yellow River in Gansu Province. In order to control regional soil erosion and facilitate better water and soil conservation, people should pay more attention to the improvement of land surface ecology in areas of rainfed farming land and grassland with low vegetation coverage.

Abstract:[Objective] Gannan Prefecture, Gansu Province, is an important water source conservation and supply area in the upper reaches of the Yangtze River and Yellow River, and it is also a crucial ecological security barrier of China. The spatial distribution pattern, temporal trend, and driving factors of water source conservation in Gannan Prefecture were studied to provide references and bases for regional water resource management and for promoting the development of healthy ecosystems. [Methods] The spatiotemporal characteristics of water source conservation in Gannan Prefecture from 2005 to 2020 were quantitatively analyzed based on the InVEST model, and an analysis of its driving factors was conducted using the geographic detector model. [Results] ① The average annual water source conservation depth and total conservation volume in Gannan Prefecture were 25.77 mm and 9.45×10⁸ m³, respectively. The overall spatial pattern showed higher values in the southern part and lower values in the northern part of the study area. Grassland and forestland dominated the water source conservation function, accounting for 65.92% and 29.43%, respectively, of the total water conservation capacity. ② Over the 16-year study period, water source conservation showed an overall increasing trend, with an average growth rate of 1.10 mm/yr. In terms of administrative divisions, areas with high water source conservation values were mainly located in the southern part of Maqu, the southern part of Diebu, and Zhouqu. In terms of topographic factors, high values were mainly concentrated in the elevation range of 3 000—4 000 m and in the slope range of 8°—25°. ③ The geographic detector analysis found that precipitation was the main factor affecting the temporal variation of water source conservation in the study area, while precipitation and land use were the dominant factors influencing the spatial distribution of water source conservation. [Conclusion] Water source conservation in Gannan Prefecture exhibited obvious temporal evolution laws and spatial distribution patterns. The dual influence of natural factors (mainly precipitation) and human activities (mainly land use) was the main driving force affecting spatiotemporal changes in water source conservation.

Abstract:[Objective] The evolvement characteristics of multifunctional tradeoff and synergistic relationship of cultivated land use were analyzed, and countermeasures and suggestions for regional optimization were put forward， in order to provide support for ensuring food security and promoting sustainable use of regional cultivated land. [Methods] Partial correlation analysis and spatial autocorrelation analysis were used to determine the spatiotemporal evolution characteristics of multifunctional trade-offs and collaborative relationships among cultivated land, and the systematic clustering method was used to partition cultivated land functions. [Results] ① During the study period, the production function of farmland in the Great Nanchang metropolitan area increased, the overall social security function decreased, and the ecological function showed a fluctuating upward trend, with little change in the landscape aesthetic function. ② The synergistic relationship between the production function of arable land and the social security function weakened over time, mainly in the eastern and southern parts of the study area. The production function and ecological function showed a balanced relationship, and the balance intensity also weakened over time, mainly in the western part of the study area. ③ Cultivated land in the study area was divided into four functional zones, among which the leading production zone should promote the centralized and large-scale management of the leading industrial production areas. The leading landscape-oriented area should develop leisure and sightseeing agriculture to achieve integrated development of agriculture and tourism. The leading ecological area should focus on green ecological agriculture and create standardized production bases. The balanced development zone had no obvious advantageous functions and could serve as a potential supplementary area for arable land functions. [Conclusion] These study results revealed the multifunctional trade-offs and synergy of cultivated land use in the Great Nanchang metropolitan area. The study area was divided into different types of areas, and suggestions were put forward for differentiated utilization of cultivated land, and therefore to provide decision-making support for giving full attention to the advantages of cultivated land in each region, making up for functional shortcomings, and promoting the diversification of cultivated land functions.

Abstract:[Objective] The temporal and spatial evolution characteristics of cropland area and grain prodution was determined in Guangdong Province, in order to provide scientific references for the formulation and implementation of policies regarding cropland protection and food security in the region. [Methods] The methods of change intensity index, center of gravity migration trajectory, and sensitivity analysis model of cropland and grain yield were used to determine the spatial and temporal change characteristics of cropland area and grain yield, and the sensitivity degree of grain yield to cropland area changes at the county scale in Guangdong Province from 2000 to 2020. [Results] ① 88.71% of the counties in Guangdong Province experienced a decrease in cropland area from 2000 to 2020. The counties with decreasing trends in cropland area developed from a concentrated distribution in the Pearl River delta region to a contiguous distribution throughout the entire province. ② 78.23% of the counties had a decrease in grain yield, and counties with significant decreases in grain production were mainly concentrated in the Pearl River delta region. ③ The centers of gravity of cropland area and grain yield both showed movement trends of “southward and westward”. The contribution of cropland area and grain yield in Western Guangdong Province played increasingly important roles in Guangdong Province. ④ The number of counties where grain yield was sensitive to changes in cropland area gradually increased over time, and the sensitive counties were increasingly concentrated in the Pearl River delta region and Eastern and Northern Guangdong Province. [Conclusion] Cropland area and grain yield in Guangdong Province had been decreasing over time, and the regions where grain yield were sensitive to changes in cropland area had been continuously expanding. These results suggest that Guangdong Province should focus on the temporal and spatial changes of cropland area and grain production for policy formulation. Based on changes in grain production, more attention should be paid to regions with higher grain yields. However, classified measures should be implemented to protect cropland, monitor grain production, and increase enthusiasm for grain cultivation.

Abstract:[Objective] The spatial differentiation characteristics of non-agriculture and non-grain cultivated land in Yanshan County, Shangrao City, Jiangxi Province, and their driving mechanism were determined, and the land use change pattern for early warning was simulated, in order to provide a scientific basis and decision-making support for the strict implementation of cultivated land use control measures. [Methods] Based on the land use data of Yanshan County in 2017 and 2021, the spatial econometric model was used to identify the driving mechanism of farmland non-agriculture and non-grain conversion, and the cultivated land change was predicted by the PLUS model, and the warning level was further defined according to the forecast results. [Results] ① The spatial differentiation characteristics of non-agriculture and non-grain cultivated land in Yanshan County was obvious. The areas with high values of the overall rate of cultivated land change and the rate change of non-grain cultivated land were clustered in the valley plains in the north of the county and in Wuyi Mountains in the south. The low-value areas were located on the east and west sides of the county. The distribution of the high-value areas of rate of change of non-agriculture cultivated land was more fragmented, and the low-value areas were relatively continuous. ② Cultivated land utilization grade and per capita cultivated land area were important factors inhibiting the non-agriculture of cultivated land. Urban-rural gradient and road density were positively correlated with the rate of non-agriculture and non-grain. Per capita cultivated land area and cultivated land reserve resources had a positive effect on the rate of non-agriculture. ③ The results of the multi-scenario simulation showed that the expansion of construction land led to a significant reduction in the amount of cultivated land in the natural development scenario. The contiguity of cultivated land increased in the cultivated land control scenario. There was a situation in which forested land squeezed the cultivated land resources in the ecological protection scenario. ④ Administrative villages with the moderate warning level for non-agriculture cultivated land were mainly clustered in townships in the southern part of the county, and the areas with high values of the warning level for non-grain cultivated land were generally concentrated in townships in the northern part of the county. [Conclusion] In the future, we should actively promote the construction of high-standard farmland, establish a compensation mechanism for cultivated land protection, improve the degree of land intensification and conservation in townships, carry out comprehensive land improvement in the entire region, improve the system of cultivated land transfer, and implement the control measures for the use of cultivated land with a balance between “occupation and compensation” and “balance between import and export”.

Abstract:[Objective] The spatiotemporal variation characteristics of different magnitudes of rainfall erosivity in Xiangshui River basin of Southern Jiangxi Province were determined, in order to provide an important scientific basis for soil erosion prevention and ecological environmental management in the basin. [Methods] Taking Xiangshui River basin in Southern Jiangsu Province as the research object, the Zhang Wenbo daily rainfall model was used with comparative analysis of rainfall erosivity to select the optimal interpolation method among ordinary Kriging interpolation (OK), inverse distance weighted interpolation (IDW), and radial basis function interpolation (RBF). The spatiotemporal variation characteristics of rainfall erosivity was analyzed in Xiangshui River basin. [Results] ① IDW was more suitable than OK and RBF in Xiangshui River basin. ② The spatial distribution differences of rainfall erosivity and annual rainfall erosivity of different magnitudes in Xiangshui River basin from 1984 to 2021 increased with the increase of magnitude, and both showed an overall trend of higher values in the north and south, and lower values in the central region. ③ The coefficients of variation of the erosion force of annual rainfall, moderate rain, heavy rain, and rainstorm in Xiangshui River basin from 1984 to 2021 were 0.26, 0.15, 0.25, and 0.47, respectively, all of which were classified as moderate variations, and the interannual variation trend was not significant. The magnitude of rainfall erosion force of different magnitudes, the proportion of annual rainfall erosion force, and the interannual change rate increased with the increase of magnitude. The oscillation cycles were basically the same, all of which were 3~4 oscillation cycles. [Conclusion] The northern part of the basin is a region with high possibility of soil erosion. Strengthening soil and water conservation measures in this region according to local conditions will help prevent and control soil erosion in the Xiangshui River basin.

Abstract:[Objective] The eco-environmental effects and spatial differentiation mechanism of the transformation of productional-living-ecological space were determined, in order to provide a scientific basis for coordinating the efficient use of land and the sustainable development of social ecology. [Methods] Taking the upper reaches of the Yangtze River as the research object, a land use transfer matrix and eco-environmental quality index were used to quantitatively analyze the spatial differentiation characteristics of the productional-living-ecological space transfer law and the eco-environmental effects in the upper reaches of the Yangtze River from 1990 to 2020. The geographical detector model was used to identify the driving factors of spatial differentiation of eco-environmental quality. [Results] ① The productional-living-ecological space pattern in the upper reaches of the Yangtze River was significantly different, and the ecological space was widely distributed in the western and southern regions of the basin. The production space was mainly concentrated in the Chengdu Plain and the intermountain basins scattered in the dense river network that was conducive to farming. The living space was scattered in the central cities such as Kunming, Chengdu, and Chongqing. ② The eco-environmental quality was generally stable and dominated by high quality. The spatial pattern of ecological environmental quality was lower in the central regions and higher in the surrounding areas. The low quality areas were distributed in clumps and strips in the Sichuan Basin and the north side of the Hengduan Mountains. The medium and high quality areas were mainly distributed in the periphery, southwest, and south portions of the upper reaches of the Yangtze River. ③ The conversion of agricultural production space into forest land production space and water ecological space, and the conversion of grassland ecological space into forest land ecological space were the main land conversion types that promoted the improvement of eco-environmental quality. In contrast, the deterioration of eco-environmental quality was closely related to the transformation of forest ecological space into agricultural production space, grassland ecological space, and industrial production space. ④ Topographic relief, slope, population density, and land use intensity were the main driving factors affecting the spatial differentiation of eco-environmental quality. The interaction between natural factors and social factors affected the eco-environmental quality in the upper reaches of the Yangtze River. [Conclusion] The eco-environmental quality of the upper reaches of the Yangtze River remains relatively stabilized in general, but the trends of local ecological deterioration should not be ignored. With regard to future policy formulation, the land use structure of the productional-living-ecological space should be optimized according to the natural conditions of each region, the main function positioning, the actual situation of the eco-environment, etc.

Abstract:[Objective] The spatiotemporal evolution characteristics and driving forces of land use changes in Lüliang City of Shanxi Province was determined, in order to provide a reference for land management and sustainable development. [Methods] Land use data from 2000 to 2020 in Lüliang City were used to determine the spatiotemporal evolution characteristics of land by using a land use transfer matrix, dynamic degree, stability degree, and standard deviation ellipse. Additionally, the PLUS model was used to determine the natural and social driving factors of land use change. [Results] ① Land use types in Lüliang City were dominated by cropland, forest land, and grassland. From 2000 to 2020, the cropland area decreased by 396.1 km², the construction land area expanded by 540.6 km², and the water area increased. The transfer of land between cropland and grassland, and between cropland and construction land dominated. Cropland was concentrated and reduced in the southeastern plain, with scattered changes in forest. Construction land expanded in clusters along valleys and roads. ② The period from 2010 to 2020 was a period of intense land use changes, with reductions in cropland, forest land, and grassland, expansion of construction land, rapid changes, and poor stability. The overall rate of land use change significantly accelerated over time. ③ Elevation had the highest contribution to land use change, followed by slope. Factors such as temperature, precipitation, population density, GDP, and distance from roads affected land use transfer. [Conclusion] From 2000 to 2020, the expansion of construction land in Lüliang City was significant, with a decrease in cropland. Heterogeneity was observed in the spatial distribution of land use, and the rate of change gradually accelerated. Controlling the encroachment of construction land on cropland, and strengthening the protection of forest resources in mountainous areas will be beneficial for sustainable regional development.

Abstract:[Objective] The effects of different fertilization modes on the vegetation diversity, development, and stability of soil aggregates and recovery of the organic carbon pool under a sea buckthorn forest were studied in order to provide a basis for the reconstructing of open-pit mine vegetation, improving soil quality, and recovering the aggregate carbon pool. [Methods] The study was conducted on the sea buckthorn demonstration base at a dumpsite of an open-pit mine of Heidaigou, Inner Mongolia. We analyzed the effects of the combined action of fertilizer modes such as inoculation with arbuscular mycorrhizal fungi (AMF) and other treatments (added weathered coal and green fertilizer) on the stability of soil aggregates and organic carbon recovery in the early vegetation restoration area of the open-pit mine dumpsite by investigating vegetation populations and collecting soil aggregate samples. [Results] Under the six fertilizer treatment modes, the experimental group inoculated with AMF, applied green fertilizer, and added weathered coal (sand, green, wind) had the best effect on the improvement of understory vegetation diversity, and the diversity index was significantly improved compared with the control treatment. The experimental group inoculated with AMF and applied with green fertilizer (sand, green) had the most significant effect on the development and stability of aggregates. The analysis of the effect of organic carbon and total nitrogen in aggregates showed that the organic carbon and total nitrogen in aggregates for the sand and green treatments were significantly higher than those in the experimental group inoculated only with AMF. [Conclusion] Different fertilization modes had positive effects on vegetation diversity, soil aggregate development, stability, and organic carbon pool restoration under sea buckthorn forest. Inoculation with AMF, application of green fertilizer, and added weathered coal should be used to increase the content of soil organic carbon and to promote the development of aggregates during vegetation reconstruction in open-pit mine dumpsites.

Abstract:[Objective] The succession of vegetation communities in the process of grassland encroachment by shrubs affects the soil organic carbon (SOC) pool, and these changes are quickly reflected by the active components of SOC. The effect of shrub encroachment on the active components of SOC in an alpine meadow was analysed to provide data support for the study of changes in the SOC pool and carbon sequestration in grasslands of the Qinghai-Xizang Plateau against the backdrop of global climate change. [Methods] Taking the Caragana erinacea shrub meadow in the Qinghai-Xizang Plateau as the research target, changes in the soil physical and chemical properties, carbon cycle enzyme activities, and SOC active components in the 0—10, 10—20 cm, and 20—40 cm soil layers at different shrub encroachment stages (non-shrub, moderate-shrub, and heavy-shrub meadow) were analysed. [Results] ① The soil water content (SWC) in the 0—20 cm layer decreased significantly by shrublading. Moreover, the SOC content in all soil layers was the highest in the heavy-shrub meadow. Additionally, the soil pH value increased significantly in the moderate-shrub meadow. ② The soil amylase activity (SAA) in the moderate-shrub meadow was significantly lower than that in the non-shrub meadow, and the soil sucrase activity (SSA) in the 10—40 cm soil layer was also significantly lower. SSA in the heavy-shrub meadow was significantly higher than that in the non-shrub meadow. ③ The readily oxidizable organic carbon (ROOC) contents in the 0—10, 10—20 cm, and 20—40 cm layers in the moderate-shrub meadow were 16.79%, 21.73%, and 31.11% lower than those in the non-shrub meadow, respectively. The dissolved organic carbon (DOC) and microbial biomass carbon (MBC) contents in the 0—10 cm layer also decreased significantly. The particulate organic carbon (POC) and ROOC contents in the 0—10 cm layer were 24.37% and 29.54% higher than those in the non-shrub meadow, respectively. The MBC and DOC contents in the 10—20 cm layer were 12.96% and 10.38% higher than those in the non-shrub meadow, respectively. The MBC and DOC contents in the 20—40 cm layer were 57.62% and 22.10% higher than those in the non-shrub meadow, respectively. ④ SOC active components were significantly positively correlated with TN, SWC, SOC, and carbon cycle enzyme activity, and ROOC was strongly negatively correlated with pH value. [Conclusion] The content of SOC active components decreased during the early stage of C. erinacea shrub encroachment in the study area, whereas SOC and its active components underwent accumulation during the later stage of shrub encroachment. This may have a positive effect on the accumulation of SOC and the improvement of soil quality in this area.

Abstract:[Objective] The effects of snow removal on soil organic carbon (SOC) compositions and carbon pool stability during the freezing-thawing period in Bayinbuluk alpine wetland were analyzed in order to provide scientific data to help the alpine wetland in coping with future climate change and to formulate a regional carbon neutrality strategy. [Methods] A field experiment was conducted in September 2022 with two treatments: snow removal and natural snowfall. Soil samples were collected during the initial freezing period (November), the freezing period (March), and the thawing period (July). Soil water content (SWC), electrical conductivity (EC), pH value, SOC content, very unstable organic carbon (F₁), unstable organic carbon (F₂), stable organic carbon (F₃), and inert organic carbon (F₄) were measured. [Results] ① There was no significant difference in SOC content after snow removal during the initial freezing, freezing, and thawing periods, but there was a decreasing trend. The SOC content after snow removal decreased by 2.87%, 6.65%, and 4.49% during the initial freezing, freezing, and thawing periods, respectively. ② There were significant differences in the SOC contents of F₁ and F₂ after snow removal in the initial freezing period (p<0.05), and these values were 8.72% and 12.26%, respectively, lower than with the natural snowfall treatment. There were significant differences in the F₃ contents among different treatments in the freezing period (p<0.05), which were reduced by 25.57% after snow removal. There were significant differences in the F₁, F₂ and F₃ contents in the thawing period (p<0.05), among which F₁ and F₃ were reduced by 22.10% and 25.57%, respectively, after snow removal, while F₂ was increased by 34.92%. There were no significant differences in other components. ③ The carbon pool activity in the initial freezing, freezing, and thawing periods was 5.99%, 9.71% and 20.39%, respectively, greater after snow removal than with the natural snowfall treatment. The SOC exhibited a decreasing trend after snow removal, but the stability of the soil carbon pool exhibited an increasing trend. With the freeze-thaw process, SOC content showed a trend of first decreasing and then increasing, while the stability of the soil carbon pool showed a trend of first increasing and then decreasing. [Conclusion] The short-term observation results showed that freeze-thaw cycles and snow cover removal had no significant effects on the SOC content and carbon pool stability, but the effect of snow cover removal on soil was greater than the effect of freeze-thaw cycles. Additional long-term observation studies will be needed in the future to better serve the scientific management of alpine wetlands and to help implement a regional carbon neutrality strategy.

Abstract:[Objective] The spatio-temporal evolution pattern and influencing factors of low-carbon utilization efficiency of cultivated land in the Songnen Plain region of Heilongjiang Province were determined in order to provide a scientific basis for ensuring national food security and low-carbon emission reduction, and to realize sustainable agricultural development. [Methods] This study used the super-efficiency SBM model to measure the low-carbon utilization efficiency of cultivated land in 33 counties (cities) in the Songnen Plain region of Heilongjiang Province from 2005 to 2020. Spatial autocorrelation and kernel density methods were used to analyze the spatiotemporal evolution characteristics and pattern of low-carbon utilization efficiency of cultivated land in various counties (cities). A geographically weighted regression model was use to determine the influencing factors of low-carbon utilization. [Results] ① During the research period, the low-carbon utilization efficiency of cultivated land in the Songnen Plain region of Heilongjiang Province exhibited an increasing-decreasing-increasing pattern, with an average value of 0.80, which did not reach the value needed for the most effective production; ② There was a significant positive spatial correlation with regard to the low-carbon utilization efficiency of cultivated land, and there were strong clustering distribution trends of high and low values in some areas. Multi-core polarization of hot spots was significant, mainly located in the northern and southern regions. Over time, the low-carbon utilization efficiency of cultivated land exhibited varying degrees of polarization characteristics, and the internal differences showed a gradual narrowing evolution trend; ③ From the perspective of influencing factors, the per capita sown area, the amount of fertilizer used per unit of cultivated land, the per capita disposable income of rural residents, and agricultural expenses had positive impacts on the low-carbon utilization efficiency of cultivated land. The multiple cropping index, the amount of machinery used per unit of cultivated land, and the urbanization rate had negative impacts on low-carbon utilization efficiency. The per capita GDP had different degrees and directions of impacts on the low-carbon utilization efficiency of cultivated land in different years. [Conclusion] The overall low-carbon utilization efficiency of cultivated land in the Songnen Plain region of Heilongjiang Province is on the rise, and there are significant differences between regions. In the future, it will be necessary to optimize resource allocation efficiency and to establish regional synergy mechanisms to promote the improvement of low-carbon utilization efficiency of arable land in various regions. The demonstration role of hot areas should also be encouraged.

Abstract:[Objective] The carbon emission characteristics and driving factors of agriculture and animal husbandry in Qinghai Province were analyzed in order to provide theoretical and empirical evidence for Qinghai government on how to promote the scientific and orderly development of green and low-carbon development of agriculture and animal husbandry. [Methods] Carbon emissions from agriculture and animal husbandry in Qinghai Province during 2000—2021 were calculated from consumption of agricultural materials, livestock and poultry breeding, and crop growth. The methods of log-mean Dietrich index (LMDI) and Tapio decoupling models were used to examine the driving factors and decoupling state of carbon emissions from agriculture and animal husbandry, and the future development tendency from 2022 to 2035 was predicted. [Results] ① Carbon emissions from agriculture and animal husbandry in Qinghai Province showed a fluctuating upward trend during 2000—2021, with an average annual growth rate of 1.61%. Intestinal fermentation and manure management during livestock and poultry breeding were the main sources of carbon emissions, accounting for 94.94% of total emissions per year. ② The effect of the level of agricultural economic development and agricultural structure could increase the amount carbon emissions, with annual contribution rates of 39.40% and 16.53%. The effects of agricultural production technology and agricultural labor force could inhibit carbon emissions, with annual contribution rates of -37.45% and -6.63%. ③ On the whole, the decoupling state between carbon emissions and economic growth of agricultural and animal husbandry in Qinghai Province was characterized as weak decoupling. Agricultural production technology and agricultural labor force scale had weak decoupling effects, while agricultural structure had no decoupling effects. ④ From 2022 to 2035, the carbon emissions from agriculture and animal husbandry will show an increasing trend, with an average annual growth rate of 1.23%, and 0.38% lower than observed from 2000 to 2021. [Conclusion] Qinghai Province should increase carbon sequestration capacity of farmland soil, reduce the intensity of intestinal methane emissions from livestock and poultry products, strengthen the leadership of carbon reduction and fixation technology in agriculture and animal husbandry, and cultivate high-quality talents in agriculture and animal husbandry, and therefore to achieve low-carbon development in agriculture and animal husbandry.

Abstract:[Objective] The influences of multi-level watershed forest changes on carbon stock changes were analyzed and the future trend of multi-level watershed carbon stock changes were predicted in order to provide a scientific basis for the sustainable development of regional forest land and the implementation of carbon neutral policy at the watershed scale. [Methods] The study was conducted for Chongqing City. We analyzed the spatiotemporal dynamic changes in forest land and carbon storage from 2000 to 2030 at the multi-level watershed scale by use of the PLUS model, landscape pattern indices, biomass expansion factor method, and gray correlation degree. Additionally, we determined the correlation between forest land pattern changes and carbon storage under natural development scenarios. [Results] ① Between 2000 and 2020, forest area increased by 3 404.55 km², primarily due to the conversion of cultivated land. The forest landscape pattern in the first-level watershed showed a tendency towards clustering and regularity, with a relatively reduced degree of fragmentation. There were distinct differences in the historical patterns and future trends of forest landscape pattern changes in the second-level watershed’s “district and group”. ② In the initial two decades, the carbon storage of forest land exhibited an increasing-decreasing trend, resulting in an overall increase. The Dongting Lake system in the first-level watershed experienced the highest increase in carbon storage, and the high-value area of carbon storage increment in the second-level watershed shifted from north to south. ③ Total carbon storage was predicted to increase by 2030, and the increase was strongly correlated with the irregular index. [Conclusion] The correlation between the forest landscape pattern index and carbon storage varied at different watershed scales. In the future, effective measures should be developed from a watershed perspective to improve carbon sink benefits and achieve carbon neutrality.

Abstract:[Objective] The temporal and spatial evolution and influencing factors of regional carbon emission in Qingdao City, Shandong Province were analyzed in order to provide a theoretical basis for promoting low-carbon development and carbon emission reduction. [Methods] Based on land use data, nighttime light data, and social and economic data of Qingdao City from 2000 to 2020, carbon emissions from land use were calculated. By constructing a fitting model between carbon emissions and nighttime light values, the spatial distribution difference and trend of carbon emissions of different land use types in Qingdao City were revealed. The decoupling status between carbon emissions and economic development in Qingdao City was analyzed using the Tapio decoupling model. The contribution degree of various influencing factors of land use carbon emissions was analyzed by using LMDI models. [Results] ① The net carbon emissions from land use in Qingdao City generally showed an increasing trend from 1.31×10⁷ t in 2000 to 3.65×10⁷ t in 2020, amounting to an increase of nearly 1.79 times. ② The overall carbon emissions in Qingdao City presented a spatial distribution pattern of “higher in the middle and lower in the surrounding areas”. Industrial energy consumption was the main source of carbon emissions from construction land, with high carbon emission areas mainly concentrated in the Jiaozhou Bay area. ③ The relationship between economic development and carbon emissions in Qingdao City had undergone a transition from “expanding connections” to “weak decoupling”, then “strong decoupling”. ④ The factors that promoted growth of carbon emissions in Qingdao City were population size and economic effect, and the factors that inhibited growth of carbon emissions in Qingdao City were energy structure and energy intensity. [Conclusion] In the future, it will be necessary to further adjust the industrial structure, accelerate the development of a low-carbon economy, and reduce carbon emissions from sources through measures such as technological innovation and energy structure adjustment.

Abstract:[Objective] Check-dams are used to directly intercept sediment and control soil erosion, which could significantly change the lateral migration process of soil organic carbon (SOC). The spatial distribution of SOC at a check-dam site and the impact of watershed land use on the distribution of SOC in the shallow soil layer (0—200 cm) of the check-dam site was analyzed in order to provide a scientific basis for the coordinated development of check-dam construction and watershed ecological environment. [Methods] Three small watersheds with significant differences in the proportion of grassland, sloping farmland, and terraced land in the Chabagou catchment were investigated. A combination of remote sensing interpretation, field sampling, and indoor testing was used to study the spatial distribution characteristics of SOC in check-dams and their response to land use. [Results] ① In the vertical soil profile, SOC content was highest in the surface soil (0—20 cm), and rapidly decreased with increasing soil depth. The variation of SOC content in the deep layer was relatively small, fluctuating around 3.5 g/kg. ② In the downstream direction of water flow, due to the influence of soil erosion and sedimentation characteristics, the SOC content was relatively higher in the middle and later sections of the check-dams. In the direction parallel to the check-dams, the SOC content on both sides was relatively higher. ③ The B check-dam with a high proportion of terraced fields in the watershed had a significantly higher mean SOC (4.4 g/kg) than both the A check-dam (3.9 g/kg) and C check-dam (3.5 g/kg). ④ The SOC content of terraced fields in the watershed was the highest, and the construction of terraced fields affected the soil particle size of eroded sediment, resulting in a significant positive correlation between the proportion of terraced fields in the watershed and the SOC content of the soil layer on the check-dam surface. The surface SOC content of grassland was relatively lower, resulting in a negative correlation between the surface SOC content of the check-dams and the grassland. The SOC density of sloping farmland was positively correlated with the SOC content on the surface of the check-dams. However, due to the small area of sloping farmland, its proportion was not significantly correlated with the SOC content on the surface of the check-dam fields. [Conclusion] Due to soil erosion, SOC sources, and mineralization characteristics, the SOC content in the surface layer of check-dams was the highest, and SOC content rapidly decreased and tended to stabilize with increasing soil depth. The high level of SOC and the erosion characteristics of finer particles in terraced land led to the highest SOC content at the B check-dam site, which had the highest proportion of terraces. The positive response of terrace construction in watersheds to SOC content of check-dam sites in the loess hilly and gully area. Terraces and check-dams not only reduce soil erosion in watersheds, but can also significantly increase SOC content and improve the microenvironment.

Abstract:[Objective] The composition and activity of soil organic carbon pools in typical vineyards in the eastern foothills of the Helan Mountains were analyzed, and the potential carbon sequestration capacity of the vineyard ecosystem in the region was quantified, in order provide a scientific basis for exploring the carbon sequestration capacity and calculating the carbon sequestration value of vineyards. [Methods] Soil organic carbon (SOC) was sampled and analysed at the park scale in a typical Xinhuibin vineyard in the eastern foothills of the Helan Mountains to study the characteristics of SOC content, density, and composition. [Results] ① The average SOC content in the 0—100 cm profile of the vineyard was 4.65 g/kg, and the SOC density was 64.5 t/hm². Although the SOC content was low and nutrients were scarce, SOC was still the main component of the carbon pool in the vineyard ecosystem. ② The soil organic carbon content in the vertical profile decreased with the deepening of the soil layer, and there was a significant difference in the SOC content between the 0—40 cm surface layer and the 40—100 cm deep layer. The SOC enrichment coefficient of the surface soil was > 1, indicating a stronger ability to fix organic carbon. ③ There was spatial heterogeneity in SOC content within the park; the spatial heterogeneity of surface soil organic carbon was constrained by differences in grape varieties and fertilisation among different fields. In contrast the spatial heterogeneity of deep soil organic carbon was mainly constrained by the formation background of the original soil. ④ The ratio of soil organic carbon activity and neutral and inert components was approximately 1∶2∶5, with a high proportion of inert components and low carbon pool activity, indicating strong stability. Although the content of inert organic carbon determined the level of total organic carbon, changes in the content of neutral organic carbon can also affect the content of total organic carbon and total carbon. [Conclusion] The soil carbon pool activity and SOC content of vineyards at the eastern foot of the Helan Mountains are low. Grape planting will eventually increase soil carbon storage and enhance the carbon sink capacity of the ecosystem.

Abstract:[Objective] The farmland ecological compensation amounts were calculated from the perspectives of food security and “double carbon”. The geographical space and economic contribution degree of the upper, middle, and lower reaches of the basin were comprehensively considered to divide the ecological compensation areas, in order to provide a theoretical reference for the construction of high-standard farmland, low-carbon agricultural development, and improvement of the benefit compensation mechanism in the basin.[Methods] We measured the profits and losses of farmland in 60 cities within the Yellow River basin from the perspective of food security, established a standard for farmland ecological compensation based on the opportunity cost method, calculated carbon emissions from agricultural resources used in production and crop growth across these cities, estimated total carbon absorption through photosynthesis during crop growth, and determined the net carbon sink of farmland in this region by considering both sources and sinks. The average carbon trading price in 2021 served as the compensation standard for calculating regional farmland ecological compensation from a “dualcarbon” perspective. Finally, by calculating farmland ecological compensation amounts separately under perspectives of food security and “doublecarbon”, we obtain comprehensive figures for dual-perspective ecological compensation within the Yellow River basin. [Results] Most cities in Qinghai and Henan provinces, where the Yellow River flows, accept certain compensation levels. Provincial capitals such as Xi’an, Zhengzhou, and Taiyuan City need to pay higher amounts due to their significant urbanisation level, industrialisation progress, and robust economic development. These findings highlighted a more pronounced conflict between local farmland security and food and ecological security. [Conclusion] In constructing high-standard farmland, carbon emissions and carbon absorption in the agricultural production process should be considered to ensure food security and to make farmland ecological compensation more reasonable, to achieve the goal of “dualcarbon” in China and to help the construction of powerful agricultural country.

Abstract:[Objective] The spatiotemporal differentiation of agricultural carbon emissions in Beijing-Tianjin-Hebei region was analyzed, and the optimal path of carbon emission reduction was explored in order to provide a decision-making reference for low-carbon agricultural development. [Methods] Agricultural carbon emissions were calculated based on the IPCC guidelines. Trend analysis was used to determine the linear changes in agricultural carbon emissions in Beijing-Tianjin-Hebei region. ArcGIS breakpoint analysis and the kernel density method were used to analyze the spatial evolution trends of the six major agricultural regions in Beijing-Tianjin-Hebei region. [Results] Overall carbon emissions and carbon intensity of agriculture in the Beijing-Tianjin-Hebei region showed a downward trend over time, especially carbon emission intensity that had been rapidly decreased since 2005. Although the proportion of total agricultural carbon emissions was small in this region, the carbon emission intensity was higher than the national level, with the highest carbon emission levels in the Bashang agricultural zone and the Jinan agricultural zone. From a spatial perspective, the northern part of the Bashang agricultural area, far from Beijing and Tianjin, as well as some counties in the central plains and Southern Hebei agricultural areas, had higher carbon emission intensity. However, the suburban agricultural area of Beijing and Tianjin, as well as the southern part of the adjacent Bashang agricultural area, maintained a light and low emission status. In addition, according to the results of nuclear density analysis, the overall carbon emission intensity of the six major agricultural regions was decreasing, with a greater degree of internal differentiation in carbon emission intensity between the Beijing-Tianjin suburban agricultural region and the Hebei central plain agricultural region. [Conclusion] The six major agricultural regions in Beijing-Tianjin-Hebei region should be engaged in regional cooperation with regard to carbon reduction and sink enhancement based on agricultural positioning and resource endowments. In the future, further consideration should be given to cross industry agricultural carbon reduction cooperation.

Abstract:[Objective] The spatial-temporal variation of carbon emissions from cultivated land for the urban belt along the Yellow River in the Ningxia Hui Autonomous Region from 2011 to 2020 was analyzed, and the ecological efficiency was evaluated in order to provide support for the construction of a low-carbon agricultural model, the promotion of agricultural carbon emission reduction, and the promotion of high-quality agricultural development in the region. [Methods] A model to estimate carbon emission from cultivated land and ArcGIS calculations were used to analyze the temporal and spatial characteristics of carbon emissions from cultivated land in the urban belt along the Yellow River in Ningxia. The unexpected output super-efficiency SBM (slacks-based-measure) model was used to evaluate the ecological efficiency of cultivated land. [Results] ① Total carbon emissions from cultivated land in the urban belt along the Yellow River in Ningxia showed an overall downward trend from 2011 to 2020. Chemical fertilizer and agricultural diesel were the primary sources of carbon emission from cultivated land. ② Carbon emissions from cultivated land in the urban belt along the Yellow River in Ningxia showed a spatial distribution pattern of higher in the north and south and lower in the middle. Pingluo and Zhongning County were the largest cultivated land carbon emission cities. ③ The trend of carbon emission intensity of cultivated land in the urban belt along the Yellow River in Ningxia was similar to that of cultivated land. ④ The ecological efficiency of cultivated land use in the urban belt along the Yellow River in Ningxia fluctuated in general, and the ecological efficiency of cultivated land in the Litong area was low. Therefore, it is necessary to adjust the input factors in the agricultural production process. [Conclusion] The spatial and temporal distribution of carbon emissions from cultivated land in the urban belt along the Yellow River in Ningxia Hui Autonomous Region is uneven, and the eco-efficiency could be unstable. Further exploration and consolidation of emission reduction measures are needed.

Abstract:[Objective] The temporal and spatial characteristics of net carbon emissions from agriculture at county scale in Fujian Province were analyzed in order to provide references for the formulation of carbon emission reduction countermeasures in Fujian Province and in other provinces and municipalities. [Methods] We constructed an accounting inventory of agricultural carbon emissions based on 12 carbon sources in plantation and livestock industries, and measured the total agricultural carbon emissions by using the carbon emission factor method. We selected seven major crops to calculate carbon uptake by combining with the agricultural characteristics of Fujian Province. We analyzed the spatial and temporal characteristics of the net agricultural carbon emissions in Fujian Province from 2001 to 2020 by using the exploratory spatial analysis method. [Results] ① During the study period, the net carbon emissions showed an inverted “V” trend of first increasing and then decreasing. In terms of carbon sources, carbon emissions from agricultural land use accounted for a larger proportion. In terms of carbon sinks, rice, vegetables, and sugarcane contributed more to carbon sequestration. The intensity of agricultural carbon emissions at most counties (cities) showed a decreasing trend, but the average annual decline was small. ② There was a significant global spatial positive correlation of carbon emissions at counties in Fujian Province, showing spatial agglomeration characteristics. The agglomeration pattern was dominated by high-high and low-low agglomeration. The spatial distribution pattern of the intensity of agricultural carbon emissions changed considerably, with an overall decreasing trend, in which about half of the counties (cities) were in the lower intensity zone. ③ The spatial class distribution pattern of counties (cities) in Fujian Province from 2001 to 2020 had changed to a certain extent, with an increase in the number of medium-emission zones and medium-low-emission zones, and a decrease in the number of high-emission zones, medium-high-emission zones, and low-emission zones, and the polarization was alleviated. [Conclusion] During 2001—2020, most counties in Fujian Province have showed a decreasing trend in agricultural carbon emissions and carbon emission intensity, and carbon emission reduction has achieved certain results, but the decline has not been large enough. In the future, policy incentives and measures should be taken to optimize industrial structure, therefore to strengthen emission reductions and to promote the transition to low-carbon agriculture.

Abstract:[Objective] The spatial and temporal evolution characteristics of carbon storage in Guiyang City, Guizhou Province, in the historical and future time series were analyzed in order to provide a scientific basis for the promotion of regional sustainable development. [Methods] ArcGIS was used to assess the spatial and temporal evolution characteristics of land use changes and carbon stocks in Guiyang City from 2000 to 2020. The coupled PLUS-InVEST model was used to predict the spatial pattern of land use, and the carbon stock change under different development scenarios in 2030. [Results] ① From 2000 to 2020, land use changes in Guiyang City came from the conversion of arable land and grassland into water areas and construction land. The area of arable land decreased by 190 km². The area of grassland decreased by 188 km². The water area increased by 43 km². The area of construction land increased sharply by 367 km². ② The total carbon storage of Guiyang City from 2000 to 2020 was characterized by the spatial evolution of carbon storage in different development scenarios. The total carbon storage of Guiyang City during 2000—2020 initially increased and then decreased, with a total decrease of 2.197×10⁶ t. The spatial distribution pattern was characterized as high in the north and low in the south, and the northern region was the main carbon sink functional area of Guiyang City. The expansion of the construction land area was the main factor decreasing carbon storage in the study area. ④ Under the natural, arable land protection, and ecological protection scenarios for 2030, the area of construction land expanded by 279, 193, and 175 km², respectively, with increases of 51.48%, 35.61%, and 32.29%. ④ The total carbon storage under the natural, arable land protection, and ecological protection scenarios for 2030 were 1.400×10⁸, 1.398×10⁸, and 1.410×10⁸ t, respectively, and these values had decreased from the values in 2020. The carbon storage always showed a spatial distribution pattern of high in the north and low in the south. The ecological protection scenario was more conducive to slowing down the declining trend of carbon storage in the study area. [Conclusion] In the future, Guiyang City should continue to strengthen the policy implementaion of returning farmland to forest land in order to restore the carbon storage level in terms of the ecological environment. In terms of urban development, a more reasonable and comprehensive development strategy should be formulated to take into account ecological protection while developing the economy.