Abstract:[Objective] The influence factors of artificial cyanobacterial crust on soil threshold wind velocity and wind erosion rate, and the effects of wind erosion prevention and control were analyzed, and the feasibility of using artificial cyanobacterial crust to prevent and control wind erosion on farmland soil was explored, in order to provide a new idea for farmland soil wind erosion prevention and control. [Methods] The effects of five inoculum amounts of cyanobacterial liquid, which were 400, 600, 800, 1 000, 1 200 ml/m², on the formation of cyanobacterial crust on farmland soil were investigated. The effects and feasibility of using artificial cyanobacterial crust to reduce soil wind erosion were tested and estimated using wind tunnel tests. [Results] Cyanobacterial crusts of different coverages could be formed under outdoor conditions by inoculating the soil with cyanobacteria liquid having different inoculum amounts. When the cyanobacteria inoculum amount was 1 200 ml/m², the coverage could reach 30% after 14 days of cultivation, and the coverage was greater than 60% after 50 days of cultivation. The biomass and thickness of the artificial cyanobacteria crust were 52 and 9 times of that of the control, respectively (p＜0.05). Artificial cyanobacterial crust significantly increased the threshold wind velocity for soil erosion and decreased the wind erosion rate. When the coverage of cyanobacterial crust was 30%, the threshold wind velocity (9 m/s) increased by 44% and the wind erosion rate decreased by more than 80%. [Conclusion] Inoculating farmland soil with cyanobacterial liquid can form a crust that can significantly change soil physical properties and enhance soil resistance to wind erosion. The formation of cyanobacterial crust on farmland soil by inoculation with cyanobacterial solution can be used as a rapid and effective method for prevention and control of soil erosion by wind.

Abstract:[Objective] The water-holding capacity of reclaimed grassland of different ages was studied in order to provide a scientific basis for water retention and soil and water conservation of reclaimed grassland in karst regions. [Methods] Reclaimed grassland of different ages (5, 10, 15, 20 yr) and cultivated land (CK) in a karst area in Anshui City, Guizhou Province was selected as the research objects, and the “space-time substitution method” was used to study litter storage, water-holding capacity, and water storage capacity. The change characteristics of soil profile bulk density, porosity, particle composition, water content, and water-holding capacity were determined for different ages of reclaimed grassland. [Results] ① The litter-layer storage capacity, maximum water-holding capacity, maximum storage capacity, and effective storage capacity followed the reclaimed grassland age order of 15 yr＞20 yr＞10 yr＞5 yr. The relationships of litter-layer water-holding capacity and water absorption rate with soaking time were characterized by a logarithmic function and a power function, respectively. ② The sand content and bulk density of the reclaimed grassland showed a trend of first decreasing and then increasing as age of reclaimed grassland increased. Changes in silt, clay, total porosity, capillary porosity, maximum water-holding capacity, and capillary water-holding capacity were opposite to the changes in soil bulk density. ③ The total water-holding capacity of the litter layer and the soil layer followed the order of 10 yr＞20 yr＞15 yr＞5 yr＞CK. The maximum water-holding contribution rate of the soil layer was more than 99%. [Conclusion] Reclaimed grassland of different ages not only increased the bioaccumulation, rainfall interception, and water-holding capacity of the litter layer, but also improved soil structure and pore status. The soil water-holding capacity gradually stabilized after 10 years. Therefore, it is recommended that planting deciduous trees after 10 years of farmland conversion to grassland.

Abstract:[Objective] The effects of Salix psammophila sand barrier decay on the composition and diversity of fungal communities were analyzed in order to provide a theoretical basis for further research on the ecological function of fungal communities in desert ecosystems. [Methods] S. psammophila sand barriers aged 1, 3, 5,and 7 years were observed, and newly laid sand barriers were used as the control. Field in-situ sampling, laboratory index determination, and Illumina MiSeq sequencing technology were used to determine the response relationships between fungal diversity and sand barrier components, soil properties, and enzyme activities during sand barrier decay. [Results] ① The relative abundance of Phialophora, Trichoderma, Knufia, Veronaea and Coniochaeta increased over time, while Didymella and Phaeococcomyces decreased over time. Fungal diversity and richness increased over time. ② Soil organic carbon, alkaline nitrogen, and dissolved organic carbon at seven years were 2.47, 1.83, and 1.71 times higher, respectively, than observed for the control. Activities of β-1,4-glucosidase and leucine aminopeptidase significantly increased by 139.36% and 35.16%, respectively. ③ Knufia, Parasola, Veronaea, and Coniochaeta were positively correlated with soil organic carbon, alkaline nitrogen, and dissolved orgainic carbon, but negatively correlated with cellulose and hemifiber (p＜0.05). The results of the redundancy analysis showed that cellulose and alkaline nitrogen were the main environmental factors that significantly affected the abundance of dominant fungal communities, and alkaline nitrogen and leucine aminopeptidase were the main factors that influenced the diversity index. [Conclusion] Both the dominant fungal genera and diversity were affected by a combination of factors during S. psammophila sand barrier decay. Alkaline nitrogen was the main influencing factor for both dominant fungal genera and diversity. Future studies should further explore the ecological functions of the dominant fungal groups in combination with the FUNGuild database.

Abstract:[Objective] The relationships between community characteristics, species diversity, and soil physical and chemical properties of Carex duriuscula in Hulunbeier steppe were analyzed in order to provide a scientific reference for the protection and restoration of grassland ecosystems. [Methods] Ninety-five sample plots typifying the Hulunbeier C. duriuscula steppe were studied. The relationships between community characteristics of four community types and species diversity and soil physical and chemical properties were studied. [Results] ① With regard to the community characteristics, aboveground biomass, species richness, and Shannon-Wiener index were significantly different among the four community types. The community of C. duriuscula-annual and biennial herbs was the highest. With regard to the soil physical and chemical properties, total nitrogen and total phosphorus were the highest in the community of C. duriuscula-rhizome herbs. ② Soil organic carbon, total nitrogen, and total phosphorus were significantly positively correlated with above-ground biomass and below-ground biomass in the C. duriuscula-clump herbs community and the C. duriuscula-forbs community. ③ Soil organic carbon, total nitrogen, and total phosphorus were significantly negatively correlated with the Shannon-Wiener index, Simpson index, and Pielou index in the C. duriuscula-rhizome herbs community and the C. duriuscula-annual and biennial herbs community. [Conclusion] There were differences in community characteristics among the four community types in the C. duriuscula steppe. Soil organic carbon, total nitrogen, and total phosphorus were the main factors affecting the differences in community characteristics and species diversity.

Abstract:[Objective] The classification of sediment particles and the accompanying distribution characteristics of carbon, nitrogen and salt in the process of soil thawing layer by layer under snowmelt runoff scenario were analyzed in order to identify the mechanism of soil freeze-thaw erosion and the induced micro-environmental effects on eroding slopes. [Methods] Soil samples were obtained from an eroding slope in the mollisol region of Northeastern China. Air-dried soil was used to fill columns that were subjected to three treatments: non-freeze-thaw, full freeze-full thaw, and gradual progressive thawing after freezing. The soil columns were completely immersed in a water bath so that thawing occurred from outside to inside. All soil samples were then fractionated by settling velocity, and the electrical conductivity (EC), pH value, soil organic carbon (SOC), and total nitrogen (TN) of each particle size were determined and analyzed. [Results] ① The freeze-thaw process reduced the proportion of the soil particles ＞500 μm and ≤125 μm, but increased the proportion of soil particles between 125 μm and 500 μm. Larger particles had higher EC, but lower SOC and TN. ② Across gradual progressively thawed layers, the outer layer (thawed earlier) had fewer particles ≤63 μm, and the inner layer (thawed later) had more particles between 125 μm and 500 μm. More specifically, EC, SOC, and TN were higher in the larger fractions from the outer layer. ③ Compared with the original soil, 64.8% of the dissolved solids were lost from the soil that experienced gradual progressive thawing, but the loss rate of SOC and TN was only 4.08% and 2.72%, respectively. The loss of dissolved solids and organic matter was greater from the inner layer than from the outer layer. [Conclusion] After freezing and thawing, the degree of fragmentation of the outer layer of soil was large, and the soil particles on the slope tended to become homogenized. Organic matter content varied significantly between particle size classes, and its distribution was more stable in small-grained soils. Salts and organic matter migrated from the inner layer of the soil to the outer layer during the freeze-thaw process, resulting in loss.

Abstract:[Objective] The change trend and main limiting factors of the ecological stoichiometric characteristics of soil and leaves in different saline habitats were analyzed in order to provide basic research data for the study of nutrient limiting factors and adaptation mechanisms in the growth and development of halophytes in arid areas, and to provide references for ecological conservation and restoration of desert plants. [Methods] The euhalophyte Suaeda microphylla and the pseudohalophyte Apocynum pictum were selected from Ebinur Lake Wetland National Nature Reserve. Soil pH value, water content, salinity, available phosphorus, ammonium nitrogen, organic carbon, total nitrogen, total phosphorus, plant leaf organic carbon, total nitrogen, and total phosphorus were measured in the selected halophytes. The relationship between the ecological stoichiometry of the leaves of the two plants and the soil of their habitats was analyzed to investigate the soil limiting factors on the ecological stoichiometry of plant leaves. [Results] ① Soil phosphorus decreased with increasing salinity, organic carbon, nitrogen, and stoichiometric ratio showed an increasing trend. Salinization degree had a significant effect on soil nutrient content; ② Leaf nitrogen for the two plants was significantly affected by soil salt, and showed a decreasing trend with decreasing soil salt content, which was consistent with the change trend of soil nitrogen content. The mean value of leaf N/P was less than 14, indicating that both plants in the study area were limited by soil nitrogen content. [Conclusion] There were differences in the coupling relationship of soil-plant ecological stoichiometric characteristics among different types of halophytes. The euhalophyte S. microphylla was mainly affected by soil pH value and water content, while the pseudohalophyte A. pictum was mainly affected by soil phosphorus and ammonium nitrogen content.

Abstract:[Objective] Nitrogen and phosphorus loss characteristics and soil fertility changes on a gentle slope of cultivated land were analyzed under optimal fertilization and cross-slope tillage in order to provide a basis for reducing nitrogen and phosphorus losses, achieving non-point source prevention and treatment, protecting cultivated land resources, and maintaining soil fertility level. [Methods] The study was conducted on a gentle slope area of the mountain and hilly area in Yunnan Province under natural rainfall conditions. A surface runoff monitoring area was established with three treatments: down-slope tillage+conventional fertilization; cross-slope tillage+conventional fertilization; and cross-slope tillage+optimal fertilization. The characteristics of nitrogen and phosphorus loss under different tillage and fertilization methods were continuously monitored from January 2019 to December 2021, and soil fertility level was analyzed by the gray correlation method. [Results] There was a significant linear correlation between nitrogen and phosphorus losses and rainfall and runoff (p＜0.01). Compared with down-slope tillage, cross-slope tillage reduced surface runoff by 20.46%—40.74%, total nitrogen loss by 19.12%—33.71%, and total phosphorus loss by 33.33%—60.08%. Compared with conventional fertilization, optimized fertilization reduced total nitrogen loss by 1.20%—51.71%. All soil fertility factors showed different degrees of improvement except that the contents of nitrate nitrogen and organic matter decreased. The gray correlation degree of each treatment showed different degrees of improvement, and the gray correlation degree of the cross-slope tillage+optimized fertilization treatment increased significantly (p＜0.05), with an increase of 26.63%. [Conclusion] Cross-slope tillage stopped surface runoff and reduced the loss of nitrogen and phosphorus. The application of cross-slope tillage and optimal fertilization application had the greatest effect on improving soil fertility level and reducing nitrogen and phosphorus losses.

Abstract:[Objective] The influences of plants on reducing ditch erosion and C, N and P loss were studied in order to provide technical support for the prevention of ditch erosion and pollution control. [Methods] The study was conducted on ditches of the Nala River basin in the intensive sugarcane growing area of Southern Subtropical China. Vetiver (Vetiveria zizanioides, a herbaceous plant) was planted at different vegetation coverage amounts 〔bare ground. vegetation coverage of 0% (BG); somewhat covered, vegetation coverage of 1%—40% (SC); mostly covered, vegetation coverage of 41%—80% (MC); completely covered, vegetation coverage of 81%—100% (CC)〕 in the ditches. Regular field investigation and monitoring of planted ditches were conducted after rainfall events from April to October, and the characteristics of erosion and nutrient loss under different vegetation coverage were quantified. [Results] ① From April to October, the width, erosion amount, and nutrient loss of ditches with different vegetation coverage gradually increased over time. Values for all three parameters followed the same order of BG＞SC＞MC＞CC; ② Compared with BG, the erosion amounts for SC, MC, and CC decreased by 37.01%, 71.60% and 75.04%; C loss decreased by 35.56%, 70.91% and 75.23%; N loss decreased by 35.89%, 71.01% and 74.39%, and P loss decreased by 34.22%, 70.59% and 77.01%, respectively; ③ Correlation analysis showed that the erosion amount for ditches was significantly negatively correlated with vetiver grass coverage and plant root density (p＜0.01), accounting for 91.94% and 89.23% of the erosion changes, respectively. [Conclusion] As vegetation coverage increased, ditch erosion and nutrient loss gradually decreased. There were no significant differences in ditch erosion and nutrient loss when vegetation coverage was between MC and CC. These results provide guidance for ameliorating ditch erosion and reducing pollutants in other water source areas.

Abstract:[Objective] The suitable configuration ratios for contour planting and replanted sugarcane on slopes were determined in order to provide technical support for reducing slope ditch erosion and nutrient loss, improving cultivated land quality and rational sugarcane planting in sugarcane planting area. [Methods] Three configuration ratios (high, medium, and low) for contour planting and replanted sugarcane were evaluated. Slope-gully erosion and nutrient losses were determined by field measurements and laboratory experiments at the growth stages of establishment growth (EG), vegetative growth (VG), grand growth (GG), and ripening growth (RG), and the factors influencing erosion and nutrient loss were determined. [Results] ① During the total growth (TG) of sugarcane, the total nitrogen (TN) and total phosphorus (TP) losses caused by gully erosion on slopes planted to sugarcane in the Nala River basin were 31.3—66.3 t/hm², 39.0—82.5 kg/hm² and 18.0—38.4 kg/hm², respectively. ② EG was the main stage of gully erosion and nutrient losses in the Nala River basin, accounting for 47.7%—57.7% of the total erosion and nutrient losses. ③ During TG, gully erosion and associated nutrient losses for higher contour ratios (H_C) were 33.03%—35.42% lower than for lower contour ratios (L_C) (p＜0.05), but the losses for medium contour ratios (M_C) were not significant compared with those of H_C and L_C. Gully erosion and nutrient losses of lower replanted ratios (L_Rp) were 27.41%—32.98% lower than those of higher replanted ratios (H_Rp), and 21.02%25.86% lower than those of medium replanted ratios (M_Rp) (p＜0.05). Litter cover and root density were the important factors affecting gully erosion and nutrient losses. ④ During TG, TN and TP losses on slopes accounted for 24.1%—39.5% and 107.0%—156.7% of the annual N and P application, respectively. [Conclusion] Planting sugarcane on slopes with a contour planting ratio of greater than 60% and a replanted ratio of less than 30% can effectively reduce soil and nutrient losses on slopes.

Abstract:[Objective] Mangroves are part of a wetland ecosystem found along tropical and sub-tropical coastlines. The soil active organic carbon composition, soil enzyme activity, and the interaction between them, under different plant community conditions was analyzed in order to predict the ecological structure and functional development trend of the mangrove area in Dongzhai Port, and provide a scientific basis for ecological restoration and protection of the mangrove wetland in Dongzhai Port. [Methods] Soil enzyme activity, active organic carbon content in the soil, and physicochemical properties of nine mangrove communities 〔Rhizophora stylosa (Type 1), Avicennia marina (Type 2), Ceriops tagal (Type 3), Bruguiera sexangula + C. tagal (Type 4), Aegiceras corniculatum + B. sexangula + Kandelia obovata (Type 5), B. sexangula + Lumnitzera racemose + A. corniculatum (Type 6), K. obovate + B. sexangula + L. racemose (Type 7), B. sexangula + Sonneratia apetala + A. corniculatum + K. obovata (Type 8), B. sexangula + S. apetala (Type 9)〕 were analyzed by field sampling. [Results] Soil organic carbon ranged from 6.57 g/kg to 74.87 g/kg in Dongzhai Port, with Type 7 and Type 1 communities having the highest and lowest soil organic carbon contents, respectively. Enzyme activity of wetland soil in each mangrove community followed the order of urease ＞ phosphatase ＞ catalase ＞ sucrase. Type 8 community had the highest urease activity, significantly higher than Type 1 to Type 6 communities. Moreover, Type 8 community also reported the highest phosphatase activity, which was significantly higher than phosphatase activity for Type 1 to Type 3 communities. On the other hand, catalase activity was highest in Type 5 community, and significantly higher than in the other communities, except Type 6 and Type 7. Type 9 community recorded the highest sucrase activity, which was significantly higher than Type 2, Type 5, and Type 8 communities. Furthermore, it was found that urease, phosphatase, and catalase activities had significant positive correlations with soil organic carbon content. Urease and phosphatase activities were significantly negatively correlated with soil pH value, and significantly positively correlated with total nitrogen (TN) and total phosphorus (TP). Catalase and sucrase activities also had significant positive correlations with TN and TP. The redundancy analysis results indicated that light fraction carbon, total organic carbon, particulate organic carbon, and microbial biomass carbon (MBC) were the main factors affecting soil enzyme activity of mangrove communities in Dongzhai Port. [Conclusion] There was a strong positive correlation between soil enzyme activity and the carbon content of active organic matter. Therefore, soil enzyme activity can be used to characterize the soil carbon pool activity in the mangrove area of Dongzhai Port.

Abstract:[Objective] The soil nutrient characteristics and influencing factors of surface soil gully erosion for low hilly terrain in the black soil area were studied in order to provide data and theoretical support for the rational use of land resources, accurate management of soil fertility, and restoration of degraded soil in the black soil area. [Methods] Surface soil gully erosion for different types of eroded ditches in Yanshou County, Heilongjiang Province was determined by measuring and analyzing soil samples from the 0—40 cm layer in each part of the erosion gully. [Results] ① The contents of soil organic matter, total nitrogen, total phosphorus, total potassium, available phosphorus, available potassium, and alkali hydrolyzable nitrogen were significantly different (p＜0.05) for different erosion gully types compared with the check treatment. As an erosion gully developed, soil organic matter decreased in the 0—40 cm layer, and the contents of total nitrogen, total phosphorus, total potassium, available phosphorus, available potassium, and alkali hydrolyzable nitrogen also decreased. These nutrient contents were significantly different (p＜0.05) in different soil layers. Soil nutrient contents decreased with increasing depth. Because of erosion deposition, the contents of soil organic matter, total nitrogen, total potassium, and alkali hydrolyzable nitrogen decreased dramatically at the head of the gully, and at the same time, the contents of soil organic matter, available phosphorus, and available potassium decreased slowly. ② The soil degradation index followed the order of CK＞A₂＞A₁＞A₃ in the 0—40 cm layer as erosion gullies developed, and the soil was gradually degraded. [Conclusion] Soil nutrients had an overall significant negative correlation with bulk density, and soil nutrients were positively correlated with water stable aggregates and clay content. Soil profile differences were the fundamental reason for the variation in soil nutrients. Erosion gully development was the secondary reason for nutrient changes. The contents of soil organic matter, total nitrogen, and total potassium were also affected by positional differences.

Abstract:[Objective] The Three-River-Source National Park (TRSNP) is considered to be the “water tower of China”, and is an important ecological security barrier in China. The soil erosion distribution law of TRSNP was studied to provide a basis for implementing ecological protection policy, soil and water conservation, and ecological civilization construction in TRSNP. [Methods] Based on the Chinese soil loss equation (CSLE), wind erosion model and freeze-thaw erosion intensity model, the soil erosion status and its distribution characteristics at different space and surface of TRSNP were analyzed by superposition analysis. [Results] In 2020, an area of 2.64×10⁴ km² suffered from soil erosion in TRSNP. Among the three sub-parks, the Yellow-River-Source Park exhibited the most extensive soil erosion, whereas the Yangtze-River-Source Park was subject to severe erosion comparatively. Soil erosion and its spatial distribution varied significantly at different elevations. Water erosion occurred mainly in the area with elevations above 4 900 m, which occupied 70% of the land area. However, 85% of the wind erosion occurred in zones with elevations less than 4 900 m. The wind erosion area with slopes between 0° and 5° accounted for 60%, which is the relatively concentrated distribution area of wind erosion. And three-quarters of water erosion areas were concentrated in regions where the slope ranged from 8° to 25°, all of which require urgent conservation measures. Grassland was the most important land cover in TRSNP, occupying about 80% of the area, with low and medium-low vegetation cover being responsible for significant soil losses. Additionally, sandy land and bare land were prone to high intensity soil erosion, which deserved special attention. [Conclusion] Two-thirds of water erosion areas were primarily located in zones where the elevation was above 4 900 m, slope gradients were between 8° and 35°, and grassland cover was below medium-low cover. Wind erosion was primarily located at elevations ranging from 4 200 m to 4 900 m, slopes were less than 5°, and grassland coverage was below medium-low cover.

Abstract:[Objective] The cultivation of safflower with micro rainwater harvesting technology on the hillslopes of the temperate desert grassland in Yili Valley was evaluated in order to provide technical support for dryland cultivation of safflower and for preventing water erosion and desertification. [Methods] The study was conducted from April to September 2021 at the Tiechanggou observation field in Yining City, Xinjiang Wei Autonomous Region. Five runoff plot treatments were set up: control, pit, horizontal terrace, square ridge, and contour ridge. Natural rainfall was observed, as well as runoff, soil loss, and safflower growth for each treatment. The soil moisture content in the 0—10 cm layer was monitored by time-domain reflectometry, and the potential evapotranspiration of safflower was simulated by the FAO Penman-Monteith model. [Results] The total rainfall during the study was 53.1 mm, and the potential evapotranspiration of safflower initially increased and then decreased. Runoff for the control treatment was the highest of all of the treatments (6.50×10^-2 mm), and safflower in this treatment did not emerge. Soil loss was greatest for the square ridge treatment (0.684 t/km²). The surface soil water content of the five treatments was the lowest in June, with a mean value of 1.50%. No runoff was observed for the pit treatment, and this treatment showed the highest plant survival number (16) and plant height at flowering (25. 3 cm). [Conclusion] Safflower growth at flowering for the five micro rainwater harvesting plots followed the order of pit＞horizontal terrace, square ridge, contour ridge＞control. Better conditions for safflower survival and growth were observed as total runoff declined.

Abstract:[Objective] The water quality of the main stream and main tributary monitoring sections of the North River in 2020 was analyzed in order to provide a reference and basis for monitoring and protecting the water environment of the North River. [Methods] The single factor evaluation method and principal component analysis were used to determine the spatial and temporal trends and driving factors of water quality for the North River. [Results] In 2020, the overall water quality of the North River monitoring sections was good. Only the sections of Shuichetou, Manshui River estuary, Huanglongshui Bridge, and Longgui met the standards for water quality grades Ⅲ—Ⅳ, and the other sections were determined to be grade Ⅱ. Water temperature and dissolved oxygen in the North River were influenced by the seasons. The water body basically remained weakly alkaline throughout the year, and the pollution levels of nutrients and organic matter were higher downstream than at upstream and midstream locations. [Conclusion] Spatial analysis showed that downstream water quality was worse than upstream and midstream water quality. The main influencing factors were nutrients and dissolved oxygen. pH value alone did not have a significant impact on water quality. The seasonal pollution degree followed the order of summer ＞ autumn ＞ spring ＞ winter. The dominant factor on water quality for the entire river was dissolved oxygen, while the dominant factors for the downstream river section were nutrients and organic matter.

Abstract:[Objective] Remote sensing technology is used to monitor and evaluate the change of urban ecological environment quality timely, dynamically and objectively, in order to provide reference for urban ecological environment planning and management. [Methods] Landsat TM/ETM⁺/OLS historical images of the same season from 2000 to 2020 were collected. The Google Earth Engine (GEE) platform was used to perform pixel-level cloud removal and chromatic aberration correction. The median value composite was used to calculate four remote sensing indicators including greenness, wetness, dryness, and heat. The remote sensing ecological index (RSEI) was constructed by principal component analysis (PCA) to evaluate the dynamic changes and spatial differentiation characteristics of urban ecological environmental quality in Nanning City with the help of the parallel cloud computing ability in GEE. [Results] The average value of RSEI was 0.615 in Nanning City, and its ecological environmental quality was observed to follow an overall fluctuating upward trend of “decreasing-increasing-stable”. The spatial heterogeneity of ecological environmental quality in Nanning City was obvious. The areas with better ecological environmental quality were mainly concentrated in the nature reserves, forest lands, grasslands and water areas, while the degraded areas of ecological environmental quality were mainly located in the cities, urban-rural transition zones and farming areas with frequent human activities and greater land use intensity. RSEI was positively correlated with greenness and wetness indicators, and negatively correlated with dryness and heat, and dryness index factor had the greatest influence on RSEI. [Conclusion] The ecological environmental quality of Nanning City was well characterized by RSEI, and the overall ecological environmental quality was at a good level from 2000 to 2020. The combination of GEE and RSEI could effectively improve the use of remote sensing images, and therefore could be used for long-term monitoring and assessing of ecological environmental quality in the urban region.

Abstract:[Objective] The spatiotemporal variation and distribution of cultivated land quality at Minhou County, Fujian Province over many years were analyzed in order to provide new ideas and new help for the study of spatiotemporal pattern evolution of cultivated land quality in complex geomorphic areas in the southeast hilly region. [Methods] The spatiotemporal statistical scanning method was introduced into multi-time series cultivated land quality monitoring, and combined with the traditional spatial analysis method to study the continuous change trend and spatial distribution of county scale cultivated land quality. Furthermore, the experimental results generated by the introduction of the spatiotemporal scanning model were compared with the results of a local autocorrelation model in the traditional spatial autocorrelation analysis method. [Results] ① The spatiotemporal scanning model was superior to the local autocorrelation model for mining high-value clustering features. ② The change amplitude and spatial distribution breadth of cultivated land quality grades at Minhou County from 2018 to 2019 were greater than in 2019—2020. ③ From 2018 to 2020, the overall cultivated land quality at Minhou County was stable from year by year, and showed an upward trend. ④ According to the variation of the spatial and temporal patterns of cultivated land quality at Minhou County, cultivated land was divided into five areas: high quality improvement area, low quality improvement area, primary key improvement area, secondary key improvement area, and moderate improvement area. [Conclusion] Replenishing nutrients, increasing water conservation, and balancing soil pH value are important practices to implement to prevent and reverse the deterioration of cultivated land quality and to maintain high quality and high yield of farmland. In addition, establishing cultivated land protection areas to prevent non-agricultural uses of cultivated land is also conducive to stabilizing and improving cultivated land quality.

Abstract:[Objective] The stability evaluation of an open-pit mining area was carried out in order to provide technical support for landform remodeling, ecological environment restoration, and soil erosion monitoring in a mining area. [Methods] The ArcHydro hydrological model and watershed self-similarity principle were used in this study. The stability of geomorphic forms in an open-pit mining area and in the surrounding undisturbed area was evaluated using the geomorphic information entropy evaluation index. The risk of soil erosion and erosion intensity in the mine area were also determined. [Results] The geomorphic information entropy of the Hesigewula open-pit coal mine area in Inner Mongolia was affected by a series of processes such as stripping, mining, transportation, and disposal, and was mostly concentrated in the index value range of 0.105—0.145. The geomorphic system development of the watershed in the mining area was mostly in the juvenile stage or middle-aged to juvenile stage. The risk of watershed erosion was high. Most of the information entropy of the original landform and undisturbed area was greater than 0.40, where the watershed geomorphic system was stable and strong, with flat terrain and small soil erosion modulus. [Conclusion] The risk of soil erosion gradually increased from south to north at the Hesigewula open-pit mine due to the original landform of the mining area, the mining sequence, and the location of the dump site. The results of this study can be used as the basis for landform reconstruction and ecological environment restoration of similar open-pit coal mines.

Abstract:[Objective] The relationship between soil column pore structure and soil erosion resistance for soil columns with Bahiagrass was analyzed in order to provide a scientific basis for the optimal arrangement of plants for soil and water conservation and to assess the benefits of planting Bahiagrass. [Methods] This study was conducted using long-term experiments of Bahiagrass grown in soil columns. Four pore indicators (pore length density, bulk density, surface area density, and pore number density) of Bahiagrass soil columns were quantified by CT scanning technology. Flushing tests using a flume with variable slopes were carried out to quantify soil erosion resistance at three slopes (10°, 20°, and 30°) and five runoff rates (0.8, 1.6, 2.4, 3.2, and 4.0 L/s). The relationships between pore structure characteristics and erosion resistance factors were then determined. [Results] Bahiagrass root system development increased during the growth period, but decreased with soil depth. The values of four pore structure indicators in 0—5 cm soil layer were much higher than those in 5—10 cm soil layer, and the average soil rill erodibility (0.026 s/m) and critical shear stress (7.0 Pa) in 0—5 cm surface layer were 0.33 and 1.54 times the values of those respective parameters in 5—10 cm lower soil layer. [Conclusion] The pore characteristics of plant root development indicated soil erosion resistance. The four pore structure indicators obtained by CT scanning were significantly related to factors such as rill erodibility. The pore surface area density was most closely related to the erosion resistance factors.

Abstract:[Objective] The dynamic characteristics of soil moisture under different land preparation measures were analyzed in order to provide a scientific basis for assessing the eco-hydrological benefits of slope land preparations and for promoting vegetation restoration in arid areas. [Methods] We used an in-situ controlled study of natural slopes, fish-scale pits, and reverse slopes of a Pinus tabulaeformis forest in a semi-arid loess area along with dynamic monitoring of soil moisture and rainfall events and HYDRUS-1D software simulations to quantify the effects of different land preparation measures on the vertical migration characteristics of soil moisture. [Results] ① The simulation accuracy of the one-dimensional unsaturated soil moisture transport numerical model for soil moisture in the 0—40 cm layer was greater than that of the 40—100 cm layer, which was suitable for the simulation of surface (0—40 cm) soil moisture. During the entire study period, under the same rainfall conditions, the soil moisture fluxes of the fish-scale pits and the reverse slope terraces were significantly higher than the soil moisture flux of the corresponding natural slope (p＜0.05). The soil moisture flux of the fish-scale pits was significantly higher than that of the reverse slope terraces (p＜0.05). ② Under individual rainfall conditions, the soil moisture fluxes of the fish-scale pits and the reverse slope terraces for the 0—40 cm layer were 9.07% and 4.02%, respectively, higher than that of corresponding natural slope plots. The average differences between the fish-scale pits, the reverse slope terraces, and the corresponding natural slope sample plots were the largest at 20 and 30 cm, which were 0.79% and 0.37%, respectively, exhibiting an overall trend of first increasing and then decreasing. When the rainfall was 5—10 mm, the maximum soil moisture fluxes of the fish-scale pits and the reverse slope terraces were 1.94% and 1.42%, respectively, at 30 cm and 40 cm. When the rainfall was more than 10 mm, the maximum soil moisture fluxes of the fish-scale pits and the reverse slope terraces were 0—20 cm, which gradually decreased with increasing rainfall. There was no significant differences in soil moisture fluxes between fish-scale pits and reverse slope terraces. ③ Under continuous rainfall, soil moisture fluxes of fish-scale pits and reverse slope terraces in 0—40 cm layer were 10.73% and 4.72% higher than the soil moisture flux of the control natural slope. The differences between fish-scale pits, reverse slope terraces and the corresponding control natural slope plots were the most significant within 0—20 cm layer (p＜0.05), and the average difference showed an overall decreasing trend. The differences between fish scale pits, reverse slope terraces, and corresponding control natural slope at each soil layer were the most significant when the rainfall was 10—20 mm (p＜0.05), and the maximum increment was at 10 cm, which was 1.35% and 0.53%, respectively. The average soil moisture flux in each layer of the fish-scale pits showed a decreasing trend, and the reverse slope terraces showed an increasing trend. Under different rainfall conditions, the depth of the maximum soil moisture flux of the fish-scale pits and the reverse slope terraces was different. When the rainfall was less than 20 mm, the fish-scale pits and the reverse slope terraces were at 10 and 20 cm, which were 1.58% and 0.72%, respectively. When rainfall was ＞20 mm, the values for both fish-scale pits and reverse slope terraces at 40 cm were 2.61% and 1.92%. There were significant differences in soil moisture flux between each layer of the fish-scale pits and the reverse slope terraces. When the rainfall was 5—10 mm, there were significant differences in soil moisture fluxes between each layer of the fish-scale pits (p＜0.05), and there were significant differences in soil moisture fluxes between 20—40 cm in the reverse slope terraces (p＜0.05). [Conclusion] The fish-scale pits and the reverse slope terraces had different effects on soil moisture. The fish-scale pits had better water retention under rainfall conditions.

Abstract:[Objective] The soil and water conservation effects of production and construction projects implemented during the construction period were determined in order to provide data support for the follow-up supervision and management of soil and water conservation of hydropower stations, and to provide a reference for the evaluation of soil and water conservation effects of production and construction projects. [Methods] The study was conducted at the production and construction project of the Lawa hydropower station in the Xizang Autonomous Prefecture of Garze, Sichuan Province. The system framework consisted of the focal points and technical regulations of soil and water conservation monitoring of production and construction projects. The analytic hierarchy process (AHP) and fuzzy comprehensive evaluation were applied to establish a soil and water conservation effect evaluation system that included 14 indicators from five aspects (red line disturbance, soil and water loss control, greening restoration, implementation of soil and water conservation measures, and soil and water loss hazards) to comprehensively evaluate the water and soil conservation effect during the construction period of the Lawa hydropower station. [Results] The comprehensive evaluation indexes of the Lawa hydropower station during 2017—2021 were 0.840 (excellent), 0.727 (good), 0.571 (average), 0.786 (good), 0.792 (good), respectively, indicating a trend of decreasing first and then increasing. The overall result was good. [Conclusion] Soil and water conservation work performed during the construction of the Lawa hydropower station (including red line disturbance, soil and water loss control, greening restoration, implementation of soil and water conservation measures, and soil and water loss damage) performed well overall, and achieved good benefits.

Abstract:[Objective] In view of problems such as unbalanced recharge, excessive ineffective evaporation, and limited water supply range in the current intermittent channel water transport exist in the lower reaches of the Tarim River, the spatial and temporal water transport modes during the growth and non-growth periods and the influence of improvements of water transport mode on the groundwater level were analyzed in order to further improve the ecological restoration system of rotary infiltration irrigation and to provide a theoretical basis for ecological restoration in the lower reaches of the Tarim River. [Methods] The study was conducted in Yingsu monitoring section of the lower reaches of the Tarim River. Groundwater depth was monitored during ten ecological water conveyances from 2012 to 2021. The Modflow model was used to numerically simulate two-dimensional flow movement of the groundwater profile in Yingsu section. The response data of ten intermittent ecological water deliveries in Yingsu section was fitted and analyzed. The process of groundwater level evolution and water quantity change during the growth period, the non-growth period, and in the artificial water channels in non-growth period were predicted and analyzed. [Results] ① Under the proposed schemes of water delivery during the growth period, non-growth period, and in the non-growth period with the artificial river channels, the groundwater levels on both sides of the artificial river channels were raised by 2.5, 0.7, and 3.2 m, respectively, compared with the current water delivery system. ② The area of groundwater depth less than 8 m in the study area was increased by 10.89%, 19.33%, and 26.17% under the three improvement schemes compared with the current water delivery system. ③ The groundwater storage capacity was increased by 10.97%, 11.88%, and 14.39% compared with the current water delivery system. [Conclusion] The artificial water channels in the non-growth period combined the advantages of both artificial water channels in the growth period and the non-growth periods, improved the utilization rate of downstream water discharge, solved the problem of difficult recovery of groundwater level under the current water delivery mode in the main river channel, and created conditions for the recovery of the inter-river ecological system and the establishment of a safe zone for downstream biodiversity.

Abstract:[Objective] The effects of environmental factors on the plant community of a slope during ecological restoration objective of Pai-Mo Highway in Qinghai-Xizang Plateau were analyzed in order to provide theoretical basis for ecological restoration plan of disturbed area in Southeast Xizang. [Methods] We studied an area of the newly constructed Pai-Mo Highway in Southeastern Xizang. We determined the relationships between community cover, species diversity indexes (Shannon-Wiener index, Simpson diversity index, Margalef richness index, Pielou evenness index), community weighted trait values (specific leaf area, leaf dry matter content, leaf nitrogen content, and leaf phosphorus content), and environmental variables (elevation, restoration measures) based on an investigation of the plant community of an ecological restoration area along a slope. [Results] ① Elevation significantly influenced the Margalef richness index and leaf dry matter content (p＜0.05); ② High-intensity measures significantly increased community cover, specific leaf area, and leaf nitrogen content (p＜0.05), but significantly decreased leaf phosphorus content (p＜0.05); ③ the SJP technique with high human intervention could significantly increase the leaf dry matter content of high-elevation plants and showed an overall greater efficacy. [Conclusion] The primary determinants of the regeneration of plant communities on slopes along the Pai-Mo Highway are elevation and restoration measures. The difficulty associated with natural vegetation restoration increases as elevation increases, and artificial restoration measures need to be intensified to prevent ecological degradation in alpine regions.

Abstract:[Objective] The urban land use in the future and corresponding waterlogging risk intensity was predicted, and the optimal control of the waterlogging risk and its implementation effects was explored in order to provide references for improving the prevention and control level of urban waterlogging and optimizing the layout of urban land use. [Methods] The study was conducted in Changsha City, Hunan Province. Urban land use layout and its waterlogging risk under a baseline scenario were predicted using the PLUS and SCS models. High-risk waterlogging areas were used as limiting conversion factors in the PLUS model to simulate the urban land layout and its waterlogging risk under a waterlogging control scenario by coupling the PLUS and SCS models. The implementation of the optimal management and control measures was verified by comparing the waterlogging risk differences under the two scenarios. [Results] The high-risk waterlogging area of construction land was predicted to be 96.47 km² in 2035 under the baseline scenario, and the total waterlogging risk area of the urban construction land under the waterlogging control scenario would be reduced by 36.94 km² compared with the baseline scenario without reducing construction land area. Furthermore, all high-risk areas in the new construction land would be avoided. [Conclusion] The waterlogging risk in urban land will increase significantly in the future. An optimization control method based on the PLUS-SCS model will help cities avoid waterlogging risk.

Abstract:[Objective] The spatial-temporal variation of terrestrial vegetation coverage in Lugu Lake Wetland Nature Reserve in Sichuan Province during 2000—2020 was analyzed in order to provide a reference for the construction and management of the reserve. [Methods] MODIS data from June to September of 2000—2020 for the Lugu Lake Wetland Nature Reserve in Sichuan Province was the data source. Correlation analysis methods such as pixel dichotomy and Theil-SenMedian trend analysis were combined to determine the spatial-temporal variation characteristics of vegetation coverage and their response to climate. [Results] ① The overall terrestrial vegetation coverage of Lugu Lake Wetland Nature Reserve in Sichuan Province slightly increased from 2000 to 2020, and increased at a rate of 0.09/10 yr. ② Vegetation coverage of the protected area was low in the lake area and the surrounding areas, and higher in the north and south areas. The spatial variation of vegetation coverage of the protected area increased overall but decreased locally. ③ The climate of the reserve (from June to September) tended to be “warmer and drier”, and fractional vegetation coverage was mainly positively correlated with temperature and precipitation. The influence of temperature was greater than that of precipitation. The specific influencing factors had spatial differences. [Conclusion] From 2000 to 2020, the vegetation coverage of the Lugu Lake Wetland Nature Reserve in Sichuan Province was good, and the vegetation coverage slightly increased over time. Temperature was the main climate factor affecting vegetation coverage. Topography and human activities, meanwhile, had some effects on the vegetation coverage of the reserve to a certain extent.

Abstract:[Objective] Plateau pika (Ochotona curzoniae) is a key species in the alpine meadow ecosystem of the Qinghai-Xizang Plateau. The coupling relationship between pika activity and meadow degradation was analyzed in order to further improve the observation system of plateau pika interference intensity and to provide more comprehensive and scientific investigation data of plateau pika activity. [Methods] An observation and grading system for alpine pika disturbance intensity (PDI) was constructed using observational data from an unmanned aerial vehicle (UAV) and deep learning methods. Spatial-temporal variation analysis was conducted using a landscape index and a coupling degree model to clarify the coupling relationship between pika and meadow degradation. [Results] ①The accuracy of the ResNet-101 model for extracting bald patches on pika mounds reached 92.7%. Slight and light pika disturbance areas accounted for 82.0% of the total area in 2019, and the moderate and high disturbance intensity areas accounted for 62.5% of the total area in 2021. The area with significantly increased PDI from 2019 to 2021 accounted for 43.0% of the total area. ②Alpine meadow vegetation was predominantly classified as moderately degraded in 2019 and 2021. From 2019 to 2021, 30.2% of the area shifted to moderately degraded to severely degraded, and 7.7% of the area experienced a significant decrease in vegetation cover. ③The landscape of the study area transformed to bald patches in a single direction, and the landscape type became more aggregated, regular, and homogenized. The dominance of bald patches in the landscape increased significantly. ④The coupling degree was increased in most regions increased from 2019 to 2021, and the interaction between plateau pika disturbance and alpine meadow degradation was enhanced from 2019 to 2021. [Conclusion] The intensity of plateau pika disturbance in the study area increased from 2019 to 2020, vegetation coverage decreased, and the landscape gradually transformed to bald patches. The alpine meadow degraded under plateau pika disturbance. The coupling effect between plateau pika disturbance and alpine meadow degradation has gradually increased, and it is therefore necessary to take more active prevention and restoration measures.

Abstract:[Objective] The ecological changes in Zhalong Nature Reserve since 2010 were studied accurately in order to provide data support and theoretical references for improving the ability to assess the value of wetland ecosystem services. [Methods] Based on remote sensing, meteorology, and ground-based observation data, the impacts of climate change on land cover, vegetation ecological quality, and net ecological productivity in Zhalong Nature Reserve were analyzed using the Carnegie-Ames-Stanford Approach (CASA) model, the Geostatistical Model of Soil Respiration (GSMSR) model, regression analysis, and other statistical methods. [Results] ① The main land cover type in Zhalong Nature Reserve was a water-bearing meadow, which accounted for 37.24% of the total area of the reserve, and was mainly located in the core area. This land cover type showed a downward trend over time in the area. ② Vegetation coverage showed a fluctuating growth pattern, with annual maximum vegetation coverage of 74.26%. ③ The vegetation ecological quality index showed an increasing trend and was characterized as being in the good level in 2019 and 2020. The average net ecological productivity (NEP) was 253.59 g/(m²·yr) (calculated in C), and showed a spatial distribution pattern of higher in the east and lower in the west. ④ The average carbon fixation during the growing season was 5.694×10⁵ tons/yr, and the oxygen release was 1.517×10⁶ tons/yr, both of which showed upward trends. ⑤ The impacts of air temperature on ecological monitoring indicators were greater than the impacts of precipitation. [Conclusion] Zhalong Nature Reserve is the most ecologically fragile area in Nenjiang River basin, and its vegetation productivity is greatly affected by climate. Therefore, it is necessary to strengthen ecological protection and restoration.

Abstract:[Objective] The spatiotemporal characteristics of soil erosion were analyzed in order to provide a reference for soil erosion control and evaluation of soil and water conservation benefits. [Methods] Based on the RUSLE soil erosion equation, the spatial-temporal evolution of soil erosion in the typical black soil region of Binxian County, Heilongjiang Province from 2000 to 2020 was analyzed with the support of RS and GIS. The effects of topographic factors and land use on soil erosion were also investigated. [Results] ① The average modulus of soil erosion in 2000, 2010, and 2020 was 893.02 t/(km²·yr), 499.84 t/(km²·yr), and 1 561.02 t/(km²·yr), respectively. The soil erosion intensity was mainly classified as slight and mild. ② The low intensity erosion was distributed across the entire region, and the high intensity erosion was mainly located in the southern mountainous area. ③ Erosion mainly occurred at elevations of 100 to 200 m. Soil erosion area was inversely proportional to slope. 0°—5° slope was the main erosion gradient zone. Soil erosion area in the direction of the north slope was larger than in the direction of the south slope; ④ The soil erosion modulus and the area of sloping farmland in the study area were larger. This area is the key area for soil erosion control in Binxian County, Heilongjiang Province. [Conclusion] From 2000 to 2020, the average soil erosion modulus initially increased and then decreased, showing a significant spatiotemporal differentiation. Topographic factors and land use change had significant driving effects on soil erosion in the study area. It can be used as a reference for soil erosion control and soil and water conservation benefit evaluation in black soil region.

Abstract:[Objective] The spatial and temporal evolution characteristics and driving factors of sand-dust weather in Inner Mongolia Autonomous Region from 1960 to 2020 were analyzed in order to scientifically understand the changes in regional sand-dust weather under the background of climate change and to provide a theoretical basis for ecological governance. [Methods] Daily data for floating dust, blowing sand, and sandstorms from 119 meteorological stations within the Inner Mongolia during 1960—2020 were analyzed to determine the spatial-temporal variation characteristics of sand-dust weather for this region using trend analysis, the M—K test, wavelet analysis, etc. [Results] ① The number and intensity of sand-dust storm days at each level exhibited a very significant (p＜0.01) downward trend in the Inner Mongolia Autonomous Region from 1960 to 2020. There was an abrupt decreasing point around 1990 for both the number of floating dust days and blowing sand days. There was no obvious change point in either the number of sand-dust storm days or the sand dust intensity index. ② The frequency and intensity of sand-dust weather was high in the western part of the region, and the high-value center was at the junction of the central and western parts of Alxa League and Wuhai City. The influence of sand-dust weather quickly weakened to the east, and regional differences were great. The weakening degree of sand-dust weather was significantly greater in the western region than in the eastern region. ③ The reduction in number of sand-dust days for the Inner Mongolia Autonomous Region resulted from (a) the decreasing number of windy days (10.1 d/10 yr，p＜0.01) and the increasing amount of precipitation in winter and spring (10.1 d/10 yr，p＜0.01) caused by significant warming, and from (b) increasing NDVI (0.036/10 yr，p＜0.01) and a better ecological environment owing to the government’s large-scale ecological governance. [Conclusion] Desertified land control is an effective way to suppress the frequency and intensity of sand-dust weather. It will be necessary to continuously promote the construction of the ecological environment and to minimize the sources of sand and dust. Moreover, we increase efforts to effectively develop and utilize water resources under the background of climate change, thereby promoting a virtuous cycle of ecological environment and reducing the harm caused by sand-dust weather.

Abstract:[Objective] The effect of growth and management of a Larix principis-rupprechtii plantation was analyzed in order to provide a reference for the scientific and rational management of L. principis-rupprechtii plantations by giving full attention to ecological functions and cost-effectiveness. [Methods] The methods used in this study included consulting archives, conducting interviews, and field investigations regarding the input costs and growth of stands of the main L. principis-rupprechtii under traditional forest management and under near-natural forest management in Yuanzhou District, Guyuan City, Ningxia Hui Autonomous Region located in the upper reaches of the Jinghe River basin. Measured parameters included input costs, average diameter at breast height, average tree height, stock volume per hectare, and aboveground biomass of per hectare. The fuzzy mathematics subordination function value method was used to quantitatively compare and evaluate the growth of trees. [Results] The growth of trees under different forest management models was significantly dissimilar. The average height, diameter at breast height, stock volume per hectare, and aboveground biomass per hectare at Huangjiagou and Diediegou under near-natural forest management were greater than under traditional forest management. The comprehensive evaluation of the growth effect of the many plantations of L. principis-rupprechtii under different management models in Yuanzhou District of Guyuan City was extremely obvious (p＜0.05). The stand growth effect followed the order (ranging from strong to weak) of Huangjiagou (0.995 8)＞Diediegou (0.628 8)＞Qingshixia(0.224 6)＞Hongzhuangliang (0.222 7)＞Madong Mountain (0.159 8)＞Chenger Mountain (0.048 6)＞Longdegou (0.000 0). [Conclusion] Tree growth under the traditional forest management model was poor. Therefore, implementation of multi-functional and near-natural target tree management measures is conducive to cultivating large diameter timber to accelerate the growth of forests.

Abstract:[Objective] Investigating the coupling relationship between the risk of soil erosion and the natural suitability of human settlements in Guyuan City, Ningxia Hui Autonomous Region provides theoretical support for the prevention and control of soil erosion in small watersheds, and thereby contributes more to the improvement of human settlements. [Methods] The PSR model and the human settlement index model were used to calculate the risk of soil erosion in a small watershed as well as the natural suitability for human settlement. The correlation and the coupling degree of the two factors were calculated to analyze their coupling coordination degree and the coupling coordination type. [Results] ① The small watersheds with moderate and high risk of soil erosion accounted for 28% of the area, and were located in the southwest and southeast. Small watersheds that were rated as unsuitable for human settlement accounted for 12% of the area, located in the southern of Xiji County and Northeastern Longde County. ② The correlation coefficient between soil erosion risk and natural suitability of human settlements was 0.61. 74% of small watersheds were found to have high coupling degree and benign resonance coupling areas, and 67% of small watersheds were found to be coordinated development and highly coordinated development areas. ③ There were 75, 36, 79, and 114 watersheds classified as coordination and synchronization type small watersheds, imbalance and co-loss type small watersheds, soil erosion lag type small watersheds, and human settlement lag type small watersheds, respectively. [Conclusion] ① Soil erosion and human settlement in Guyuan City had high correlation, high coupling degree, and significant mutual promotion effects. ② There were 79 small watersheds with lagging risk of soil erosion that needed to be controlled, and 36 dysfunctional co-loss type small watersheds should be treated and reconstructed according to the local conditions.

Abstract:[Objective] The characteristics of sand-driving wind and sand-transporting potential are the key indexes for evaluating the regional wind energy environment. The change characteristics of the wind regime and transport potential of sand-driving wind in the Northeast Bayan Wendur Desert were analyzed, the dynamic wind characteristics and the intensity of the wind energy activity near the ground were revealed, and the regional wind energy environment was evaluated, in order to provide a theoretical basis for the study of sand movement and scientific options for sand movement prevention and control. [Methods] Wind data were acquired from a meteorological station on the northeast edge of the Bayan Wendur Desert from 2017 to 2021, and the characteristics of the sand-driving wind and sediment transport potential in the region were analyzed. [Results] ① The annual average frequency of sand-driving wind was 43.70%, and the average sand-driving wind speed was 7.57 m/s, both of which were the highest in spring. The sand-driving winds in different seasons and the annual average were mainly westerly (W, WSW, SW) and southerly (S, SSE, SE). ② The annual average sediment transport potential (DP) was 68.36 VU. The composite sediment transport potential (RDP) was 29.39 VU. The wind direction variability index (RDP/DP) was 0.43. The composite sediment transport potential direction (RDD) was 91.33°. The DP and RDP in spring were significantly greater than in other seasons. ③ The influence of the average wind speed on the sediment transport potential in the study area was greater than the frequency of the wind speed. The intensity of sand movement was mainly determined by wind speed. [Conclusion] The northeast edge of the Bayan Wendur Desert generally belongs to a low wind energy environment. The surface sand material is transported eastward throughout the year. Spring is the most important period of wind and sand activity. June is the key period for the construction of artificial protective forests and aerial-seeding afforestation for sand control. We recommend that the direction of planting protective forest shelterbelts and for aerial seeding of forest seeds be perpendicular to the direction of sand transport potential so as to block the continuous eastward movement of sand.

Abstract:[Objective] The relationship between water adaptation and the distribution pattern of desert shrubs at the regional scale was studied and the process and mechanism of plant population response to environment in arid and semi-arid areas was analyzed in order to provide a basis for further understanding the co-evolution relationship between plants and environments. [Methods] The spatial distribution pattern and water use strategy of Reaumuria songarica populations were analyzed by using point pattern analysis and hydrogen and oxygen stable isotope tracing techniques. [Results] ① Under the complete spatial randomness model, the R. songarica population was uniformly distributed at ＜3 m scale, and aggregated at ＞32 m scale. The intra-population ecological relationship changed from competition to promotion. After habitat heterogeneity was eliminated, the population showed random distribution at ＞ 30 m scale, and the intra-population ecological relationship showed a weakening trend, indicating that habitat heterogeneity played an important role in the formation of the spatial distribution pattern of the R. songarica population. This result indicated that habitat heterogeneity played an important role in the formation of the spatial distribution pattern of R. songarica populations at large scales. ② As the multi-year average precipitation decreased, the water use depth of the R. songarica population deepened from 0—20 cm to 60—100 cm. The density of the R. songarica population showed a highly significant negative correlation with multi-year precipitation (p＜0.01). The change in vegetation cover at the sample site was mainly influenced by the herbaceous cover, and the change in R. songarica vegetation cover was not significant. [Conclusion] As multi-year average precipitation decreased, the distribution pattern of R. songarica populations was affected by environmental heterogeneity, and R. songarica adapted to environmental stress by increasing plant density and using deeper soil moisture.

Abstract:[Objective] Under total carbon emission control, an equitable and scientific allocation of carbon emission quota among provinces of China is a key approach for achieving the “dual carbon” goal, as well as an important cornerstone of the carbon emission trading system. The marginal cost of carbon emission reduction was analyzed under different scenarios with regard to the results of carbon emission quota allocation in order to determine the optimal carbon emission quota budget scheme at the lowest cost, thereby providing a theoretical basis for subsequent regional allocation work and a reference for the formulation of regional carbon emission reduction schemes. [Methods] An ecological index was introduced based on the carbon quota budget index established in previous studies. Four scenarios (including equity, efficiency, ecology, and balanced equity-efficiency-ecology) were evaluated. The slacks-based measure (SBM) dual model was used to calculate the regional marginal carbon emission reduction cost under different scenarios, and the optimal budget scheme was determined based on these results. [Results] Under the scenarios of equity, efficiency, ecology and balanced, the average marginal costs of carbon emission reduction were 0.295 million yuan/t, 0.312 million yuan/t, 0.291 million yuan/t, and 0.309 million yuan/t, respectively. When the ecological index was introduced, the emission reduction cost of the scheme was significantly lower, and it can be inferred that the carbon sink offsets a portion of the carbon emissions that are more difficult and costly to reduce. The cost of emission reduction under the balanced scenario was significantly higher than under the equity and ecology scenarios, indicating that improvement in carbon emission efficiency will lead to an increase in marginal carbon emission reduction cost. [Conclusion] The carbon emission quota under the ecology scenario was the best scheme for achieving the “dual carbon” goal with the lowest marginal carbon emission reduction cost. Attention should be paid to the formulation of regional carbon emission schemes and carbon trading mechanisms.

Abstract:[Objective] The spatiotemporal characteristics and factors influencing the value of forest carbon sequestration in Henan Province were analyzed in order to provide a reference for promoting the realization of “carbon peak and carbon neutrality”. [Methods] The value of forest carbon sequestration in Henan Province from 2010 to 2020 was evaluated through the stock expansion method and the afforestation cost method, and the temporal variation characteristics of forest carbon sequestration value were analyzed. The Moran index was used to explore the spatial aggregation characteristics, and an extended STIRPAT model was constructed to analyze the factors affecting the value of forest carbon sequestration. [Results] ① The value of forest carbon sequestration in Henan Province showed a continuous rising trend which increased from 4.18 billion yuan in 2010 to 6.71 billion yuan in 2020. Carbon sequestration values exhibited a pattern of “higher in the west and south, lower in the east and north” in Henan Province, and there was a significant positive spatial aggregation effect. The areas with significant high carbon sequestration values were located in Western and Southern Henan Province, while there were only two areas with significant low carbon sequestration values. ② In addition to the negative impact of carbon sink intensity on the value of forest carbon sequestration in Henan Province, the proportion of forest area, urbanization ratio, forestry industry ratio, and per capita GDP all showed positive impacts. The proportion of forest area was the most important factor promoting the growth of forest carbon sequestration values. [Conclusion] There is great potential for forest carbon sequestration in Henan Province, and the realization of forest carbon sequestration should be promoted regionally in the future.

Abstract:[Objective] The temporal and spatial variation of carbon emissions due to land use changes and the factors influencing carbon emissions in Yunnan Province were analyzed in order to provide a theoretical basis for optimizing land use structure and achieving the low-carbon development goal in Yunnan Province. [Methods] Carbon emissions for Yunnan Province were calculated based on land use and fossil energy consumption data in Yunnan Province in 2005, 2010, 2015, and 2020. Spatial visualization and spatial autocorrelation were used to study the temporal and spatial variation and spatial agglomeration characteristics of carbon emissions from 2005 to 2020. The influencing factors were analyzed by geographical detectors. [Results] ① From 2005 to 2020, the area of construction land in Yunnan Province increased the most, with a dynamic change of 7.90%. ② Regional net carbon emissions increased rapidly, with an annual increase of 6.5%. The spatial pattern of carbon emissions was characterized as “higher in the central region and lower in the surrounding area”. The carbon footprint increased significantly during the study period, and the carbon ecological carrying capacity was relatively stable, resulting in an increasing carbon ecological deficit. ③ Population size, economic level, industrial structure, land use, etc. promoted the increase in carbon emissions for cities and counties in Yunnan Province. [Conclusion] In Yunnan Province, measures should be taken in the future to protect or reasonably increase the area of carbon sinks (such as forest land) and to strengthen dynamic monitoring, control the area of construction land and total energy consumption, explore the carbon compensation mechanism, and employ the radiation effect of carbon sink areas.

Abstract:[Objective] The carbon sinks of soil and vegetation were monitored and evaluated in order to provide technology and methodology for implementing dynamic monitoring and evaluation of carbon sinks for soil and water conservation projects, and to provide theoretical and methodological support for soil and water conservation projects to participate in carbon emissions trading, and to research and formulate relevant rules. [Methods] The carbon storage capacity of the vegetation carbon pool and soil carbon pool in Luodihe small watershed at Changting County, Fujian Province during 2001—2022 was calculated through field sampling analysis and LiDAR collection of relevant parameters. Carbon sink capacity of various soil and water conservation management measures in the small watershed was evaluated. [Results] ① After 21 years of comprehensive management, various soil and water conservation measures in the study area have significantly improved the role and capacity of carbon sinks. The carbon storage of the small watershed increased by 3.97×10⁴ t, with an average annual increase of 1.89×10³ t/yr. ② The carbon storage of soil and vegetation carbon pools increased by 73.73% and 346.41%, respectively, during 2001—2022. The carbon sink of the small watershed reached 3.05×10⁴ t, of which 1.66×10⁴ t was attributed to the soil carbon sink and 1.39×10⁴ t was attributed to the vegetation carbon sink. ③ There were differences in the ability of various measures to increase the carbon sinks. Chestnut forest land and fertilized Pinus massoniana forest land increased carbon sink the most obviously, followed by coniferous and broad-leaved mixed forest, nursery and managed P. massoniana, horizontal grade land preparation of P. massoniana forest, and finally close management and bayberry forest land. [Conclusion] Various soil and water conservation measures had obvious effects on carbon retention, carbon sequestration, and carbon sink increase. The carbon sink capacity of forest land such as chestnut forest and fertilized P. massoniana forest land with land preparation, afforestation, and fertilization and breeding measures was even more significant. These practices provide an effective means for improving the efficiency of soil and water retention and for increasing carbon sink.

Abstract:[Objective] Land use change is one of the important driving forces for increasing carbon emissions and the environmental quality. The temporal and spatial pattern changes and effects of land use carbon emissions were analyzed in order to provide a theoretical basis for the formulation of low-carbon development strategies. [Methods] The internal relationships between land use changes and carbon emissions, carbon emission intensity and ecological effect were determined based on gray theory and ecological carrying coefficient by using land use and energy consumption data for 22 counties in Ningxia Hui Autonomous Region from 1980 to 2020. [Results] ① There was a close correlation between carbon emission changes and land use changes. The correlation between construction land and carbon emissions was the largest (0.95). ② Net carbon emissions of land use types in Ningxia increased by 5.24×10⁷ t and had a growth rate of 625.43% from 1980 to 2020. This pattern was associated with significant increases in construction land area and carbon emissions (average annual rates of 4.42% and 2385.85%, respectively) during the period of 1980—2020. Additionally, grassland area decreased by 2.95×10⁵ hm², and the carbon sink decreased by 5.80×10⁴ t. Forest land was the main carbon sink, accounting for more than 75% of the carbon sink in 2020, and increased with increasing area. ③ The carbon emission intensity of land use in Ningxia increased at an average annual rate of 0.25 t/hm² from 1980 to 2020, and the coverage area of moderate and above grades increased gradually. A spatial distribution pattern of carbon emission intensity for cities along the Yellow River developed higher than observed for the central and southern regions. ④ Due to differences in county economic level and natural environment, the spatial differences in ecological support coefficients of carbon emissions for the 22 counties in Ningxia was obvious, and the distribution pattern of carbon sink capacity was weak in the north and strong in the south. [Conclusion] The carbon emission intensity of land use in Ningxia gradually increased from 1980 to 2020. The carbon ecological capacity of counties along the Yellow River in the north gradually decreased. The carbon ecological capacity of counties in the central and southern regions increased, but the pressure of emission reduction was greater. We recommend optimizing the spatial pattern of construction land, increasing the area of mixed forests, and enhancing forest carbon sink capacity.

Abstract:[Objective] The influence of land use changes on carbon storage were studied under the expansion of urbanization in Hainan Island to reveal the spatial-temporal evolution pattern of carbon storage and to predict future development trends in order to provide scientific evidence for optimizing the spatial layout of the national territory and for protecting ecologically sensitive areas. [Methods] Based on land use data from 1980 to 2020, this research showed the spatial-temporal changes of carbon storage for Hannan Island. The data were used with the carbon storage module of the InVEST model. The FLUS model and the InVEST model were coupled to simulate land use and carbon storage changes for Hainan Island in 2030 under three scenarios: the natural development scenario, the rapid development scenario, and the ecological protection scenario. [Results] ① The main types of land use on Hainan Island were forest land and cultivated land. From 1980 to 2020, the areas of cultivated land, grassland, forest land, and unused land decreased to varying degrees. The area of construction land and water increased over that time period, with the fastest growth rate being 83.4% for construction land. ② Carbon storage for Hainan Island was generally characterized as “higher in the middle and lower in the surrounding areas”. Carbon storage changed slightly from 1980 to 2000, with a decrease of about 0.03%. From 2000 to 2020, the urbanization process on Hainan Island accelerated, and the loss of carbon storage also increased. The average annual loss was about 372 t, and the cumulative loss of carbon storage was 7 439 t. ③ The prediction results showed that construction land will continue to expand in the future, and carbon storage on Hainan Island in 2030 will decrease under the three scenarios. Under the rapid development scenario, the land use change of construction land was the largest, and carbon storage was the most vulnerable to loss, followed by the natural development scenario. The ecological protection scenario had the smallest change. [Conclusion] Land Use Planning for Hainan Free Trade Port in the future should focus on the protecting key ecological areas such as the central mountainous areas, strengthening the nature reserves of Hainan Island, optimizing the land use pattern, and strictly controlling the transformation of forest land, cultivated land, and wetlands into construction land. The efficiency of carbon sequestration should be improved, and forest carbon sinks should be increased to achieve regional sustainable development.

Abstract:[Objective] Ecosystem services value (ESV) is one of the important measures used to evaluate whether regional land use change is scientific. ESV is related to regional sustainable development. ESV and terrestrial carbon storage (TCS) changes in coastal cities were evaluated in order to provide a basis for economic development and ESV regulation in Dalian City, Liaoning Province. [Methods] Five periods of land use data and related data from 2000 to 2020 were analyzed in this study. Land dynamics, the equivalent factor method, a land transfer matrix, ESV contribution rate, TCS, and principal component analysis were used to calculate the land use change dynamics in Dalian City and their impacts on ESV, TCS, and terrestrial carbon storage value (TCSV). [Results] ① Construction land in Dalian City mainly encroached on farmland and forest land in the southwestern coastal area. ② During the four time periods from 2000 to 2020, ESV in Dalian City initially decreased and then increased, and the decline continued to intensify. The decrease in arable land area and the increase in construction land area had a direct impact on the maintenance of ecosystem service functions. ③ During the four time periods from 2000 to 2020, TCS and TCSV in Dalian City initially increased and then decreased, and the decline continued to intensify. The reduction of forest area directly affected the maintenance of TCS function. ④ In the land use transfer matrix for Dalian City from 2000 to 2020, farmland, forest land, and grassland were mainly transferred out, while construction land was mainly transferred in. The contribution of ecosystem services varied among different land use types, with contributions ranging from cultivated land, forest land, wetlands, water bodies, grasslands, and unused land. ⑤ The changes in ESV and TCS in Dalian City from 2000 to 2020 were mainly influenced by economic growth, adjustments to the three major industrial structures, and the development of urbanization level. [Conclusion] From the perspective of economic development, ESV improvement, TCS capacity improvement, and sustainable development in Dalian City, it is necessary to focus on the conflict between the expansion of coastal construction land and ecological and agricultural land, strengthen the protection of northern forest and grass ecological land, accelerate the ecological environment restoration work in coastal areas, enhance the carbon sequestration capacity of ecological land, and avoid unrestricted blind expansion of construction land.

Abstract:[Objective] The temporal and spatial differences of agricultural carbon budget and carbon compensation potential were analyzed based on the dual perspectives of carbon emission and carbon absorption in order to provide a theoretical reference for the comprehensive green transformation and coordinated development of agriculture in Hunan Province. [Methods] Exploratory spatial data analysis, absolute β convergence, parameter comparison, and GIS spatial analysis were used to empirically analyze the spatial and temporal differences of the agricultural carbon budget, spatial correlation and convergence characteristics of the carbon compensation rate, and regional differences in agricultural carbon compensation potential of counties in Hunan Province. [Results] The overall agricultural carbon emissions of counties in Hunan Province exhibited a structural form of “higher value areas in the center, and gradually decreased outwards”. Farmland soil was the main source of carbon emissions. The agricultural carbon emission intensity of counties exhibited a pattern of “higher in the southwest, lower in the northeast” and significantly decreased year by year. The overall agricultural carbon sequestration in the counties exhibited a spatial pattern of “higher in the east, central, and north regions, lower in the southwest”. Agricultural carbon sequestration capacity gradually increased across the region. Rice contributed the most to agricultural carbon sequestration, and agricultural carbon absorption intensity significantly increased and its spatial pattern significantly changed. The agricultural carbon compensation rate in the counties was a net carbon source, with significant positive spatial correlation and convergence, and the spatial clustering and correlation characteristics were obvious. The potential of agricultural carbon compensation in the counties showed a significant imbalance in space, with the proportion of medium and higher carbon compensation counties reaching 60.66%, indicating that the agricultural carbon compensation rates of counties in Hunan Province were lower, thous there was still a large potential for increasing carbon compensation. [Conclusion] Regional cooperation should be further strengthened, and green transformation should be jointly promoted by interested parties who should give full attention to the radiation driving effect of agricultural carbon compensation rate hot spots in order to maintain the development of excellent low-carbon agriculture in regions with higher agricultural carbon compensation capacity. The future work should focus on the development of green agriculture in regions with medium and high carbon compensation potential, and on narrowing the development gap of low-carbon agriculture in all Hunan Province.

Abstract:[Objective] The ecosystem carbon storage and its response to land use changes in Fujian Province were analysed in order to provide a reference for ecosystem protection. [Methods] Based on land use data and carbon density data, the InVEST model was used to simulate carbon storage in Fujian Province in 1980, 2000, and 2020. The spatiotemporal characteristics of carbon storage and land use were analyzed using the distribution of cold spots and hot spots, transfer maps, and a transfer matrix. The response of carbon storage to land use changes was analyzed. [Results] ① Carbon storage in Fujian Province was relatively high on the whole, and more than 82.5% of the region was above medium carbon storage (＞3 000 t), mainly located in mountainous and hilly areas, which were also hot spots of high carbon storage. Ares of high (hot spots) and low (cold spots) of carbon storage concentration transferred less. Total carbon storage fluctuated slightly from 1980 to 2020, and relatively more carbon storage transferred between different carbon storage levels from 2000 to 2020. ② Land use/cover in Fujian Province was mainly forest land (61.4%—62.9%), followed by cultivated land (16.9%—18.3%) and grassland (15.2%—17.2%). Land use/cover change was relatively stable from 1980 to 2000, and more intense from 2000 to 2020. ③ Total carbon storage values in forest land, grassland, and cultivated land were relatively high, while total carbon storage in water bodies, construction land, and unused land were relatively low. Total carbon storage in cultivated land decreased over time, while total carbon storage of construction land increased. The area of forest land and grassland both increased and decreased. The largest transfer of total carbon storage caused by land use/cover changes was observed in forest land, followed by grassland and cultivated land. The net transfer of total carbon storage was negative for forest land, and positive for the other land use classes. The largest carbon loss was observed for the transfer of forest land. [Conclusion] Cultivated land, forest land, and grassland were the main types of land use in Fujian Province contributing to higher carbon storage, and their mutual transfer resulted in carbon storage changes.

Abstract:[Objective] The changes in land use under different low-carbon scenarios were simulated, and the differences in carbon storage and carbon emissions under multiple scenarios were compared in order to provide relevant suggestions for the low-carbon development of Nanchang City, Jiangxi Province. [Methods] The land use structure in 2030 was optimized based on the maximum carbon storage scenario and the minimum carbon emission scenario. The FLUS model was used to simulate the spatial distribution characteristics of land use in Nanchang City under multiple scenarios. [Results] ① According to the optimization results of the quantity structure, the carbon emissions of land use under the maximum carbon storage and minimum carbon emission scenarios were smaller than under the natural development scenario, and carbon storage was greater than under the natural development scenario. Overall, the effect of quantitative structure optimization of land use under the scenario of maximum carbon sink was better. ② According to the spatial structure simulation results, construction land under the low-carbon scenario was relatively concentrated in spatial distribution compared with the natural development scenario. The areas of carbon emission reduction and carbon storage increase were mainly located in the central and southern regions. [Conclusion] It is suggested to optimize land use structure, implement ecological protection and cultivate land protection policies, limit excessive expansion of construction land, and strengthen the regulation of key areas, so as to achieve the goal of carbon peak and carbon neutrality of Nanchang City as soon as possible.

Abstract:[Objective] One of the main drivers of terrestrial ecosystem carbon storage is land use change. The spatial-temporal response relationship between land use and carbon storage evolution in Zhengzhou City, Henan Province was analyzed based on the logic of “past-present-future” in order to provide references for realizing ecological security and sustainable development. [Methods] The spatial-temporal distribution of carbon storage from 2005 to 2020 was quantitatively evaluated using GIS and the InVEST model. Then, combined with the PLUS model, the spatial-temporal changes of land use and carbon storage were simulated for 2050 under a natural development scenario and an ecological conservation scenario. The degree of spatial correlation was evaluated at the grid scale using Moran’s I and the Getis-Ord G_i^* statistic for hot spot analysis. [Results] ① From 2005 to 2020, cultivated land was continuously converted to construction land, with a cumulative transfer of 1 004.98 km², resulting in significant changes in the land use structure of Zhengzhou City. The decrease in ecological land area under the ecological conservation scenario was better than under the natural development scenario. ② The rapid expansion of urbanization in Zhengzhou City produced carbon storage in 2005 and 2020 of 6.59×10⁷ t and 5.67×10⁷ t, respectively. Over the past 15 years, the high-carbon-intensity land class was transferred, and the spatial distribution of carbon storage was characterized by a pattern of “higher in the west, lower in the east, medium in the north and south, and lower in the central region”. Under the scenarios of natural development and ecological conservation, the carbon storage decreased by 8.27×10⁶ t and 1.80×10⁶ t, respectively, and cultivated land played an important role as a carbon sink. ③ The spatial distribution of carbon storage was agglomerative, with an uneven distribution of cold and hot spots. The degree of fragmentation of hot spots was moderate under the ecological conservation scenario. Gongyi City and Dengfeng City were always the regions with a high degree of carbon storage agglomeration. [Conclusion] The spatial-temporal distribution characteristics of carbon storage were closely related to changes in land use structure. In future land use planning of Zhengzhou City, people should take appropriate ecological conservation measures to optimize the land use pattern and to enhance the carbon sequestration capacity of the ecosystem.

Abstract:[Objective] The spatial and temporal distribution pattern of carbon storage at Wuhu City, Anhui Province from 2011 to 2021 were analyzed, and the influence of ecological environmental factors, topographic factors, meteorological factors, and land use degree on carbon sequestration capacity were determined in order to provide a reference for land resource management and green agricultural development at Wuhu City. [Methods] The carbon storage module of the InVEST model was used to quantitatively determine the spatial distribution of carbon storage, to explore the effects of land use degree, topography, meteorology, soil erosion, and other factors, and to calculate the hot spots of carbon storage based on correlation analysis superposition using land use data from 2011, 2015, and 2021 at Wuhu City. [Results] ① Carbon storage at Wuhu City has declined by 4.15×10⁵ t in recent years due to land use changes, with an annually decreasing trend. The carbon sequestration capacity of grassland was lower than that of cultivated land. The carbon storage capacity of cultivated land was 7.41×10⁶ t, while that of forest land was 5 489.01 t/km². ② Land use type, elevation, slope, and land use degree were the most important natural factors determining the spatial distribution of carbon stocks, which increased gradually step by step with altitude and slope. The overall distribution of carbon stocks was “lower in the north and higher in the south.” ③ Carbon storage and soil conservation were significantly and positively associated, mutually reinforcing, and synergistic among ecological and environmental variables; yet, there was a trade-off with soil erosion. ④ Carbon storage in the south showed a pattern of “high-high accumulation”, accounting for 18.77% of the total carbon accumulation, whereas carbon storage in the north showed a pattern of low-low accumulation, accounting for just 2.73% of the total carbon accumulation. The hotspots of carbon storage declined over time as a result of the effect of resource development and usage, with 11.95% of the area classified as excellent concentrated in the southern mountain forest. Certain areas were found to be vulnerable and will need to be conserved and optimized. [Conclusion] From 2011 to 2021, the total amount of carbon sequestration at Wuhu City decreased year by year, and the carbon sequestration rate showed a trend of weakening over time, while carbon sequestration capacity was relatively stable. Carbon sequestration capacity in the northern part of Wuhu City was relatively weak, and could be increased through land management optimization.

Abstract:[Objective] The spatial-temporal characteristics and decoupling effects of agricultural carbon emissions at Xuzhou City, Jiangsu Province were analyzed in order to provide a theoretical basis and data reference for green, high-quality sustainable development of agriculture and the benign growth of the agricultural economy in Xuzhou City, and its surrounding resource-based cities in the future. [Methods] The total amount, intensity, and structure of agricultural carbon emissions at Xuzhou City from 2000 to 2020 were measured using the emission coefficient method, and their decoupling relationship with agricultural economic development was determine based on the Tapio decoupling model. [Results] ① The overall trend of agricultural carbon emissions at Xuzhou City could be described as M-shaped (rapid rise-fluctuating rise-rapid decline) from 1.61×10⁶ t in 2000 to 1.69×10⁶ t in 2020. The contributions of factors affecting agricultural carbon emissions followed the order of arable land use (46.44%), crop cultivation (31.90%) and livestock breeding (21.66%), with chemical fertilizers being the most important carbon source; ② Agricultural carbon emission at Xuzhou City varied significantly among districts (counties and cities) and had undergone a long-term evolutionary process from rising to falling, with a spatial distribution pattern of “higher in the middle and lower in the surrounding areas”, with Pizhou City being the most prominent; ③ Xuzhou City’s agricultural carbon emissions and agricultural economic development have generally undergone a process of “weak decoupling—strong negative decoupling—expansion of negative decoupling—strong decoupling”, and has mainly manifested as strong decoupling since the 13th Five-Year Plan. [Conclusion] Xuzhou City’s agricultural carbon emissions are becoming more and more reasonable as the concept of low-carbon emission reduction continues to deepen. Agricultural economic development has also achieved clear and convincing effects.

Abstract:[Objective] The effects of ecological engineering restoration technology on soil aggregate stability and organic carbon distribution were analyzed in order to provide a scientific basis for improving soil structure stability and carbon sink function of different ecological restoration slopes at Xiangjiaba Hydropower Station. [Methods] Four different ecological restoration slopes at Xiangjiaba Hydropower Station were studied: vegetation concrete (CBS), thick base material spraying (TB), frame beam covering soil (FB), and external soil spraying (SS). The distribution and stability of soil aggregates and the characteristics of organic carbon content were determined by the wet sieve method for two natural restoration slopes: natural forest (NF) and abandoned land (AS, used as the control). [Results] ① The soil for each slope was dominated by large aggregates ＞0.25 mm. The macroaggregate content in natural forest was the highest (81.83%). The vegetation concrete and thick base material slope had the second highest macroaggregate contents, and the macroaggregate content of waste residue land was the lowest (55.19%). The MWD and GMD values of the four artificial ecological restoration slopes were lower than the values of the natural forest, and higher than the values of the waste residue land. The values of the thick substrate slope were the highest (2.96 mm and 1.47 mm), respectively. The fractal dimension (D) of the soil spray seeding and slag field was significantly higher (p＜0.05) than observed for the other four slopes. ② The organic carbon contents of macro aggregates with particle size ＞0.25 mm were the highest in all ecological restoration slope measures. In addition to soil spray seeding and waste residue land, other restoration measures and natural forests had the largest contribution rate of ＞2 mm soil aggregates. ③ Correlation analysis showed that SOC was significantly positively correlated with MWD, GMD, and R_0.25 (p＜0.01). Aggregates of size ＞5 mm and 5—2 mm were significantly positively correlated with soil MWD, GMD, R_0.25, and SOC (p＜0.01), and significantly negatively correlated with D (p＜0.01). [Conclusion] In the study area of Xiangjiaba Hydropower Station, thick substrate spraying technology and vegetation concrete ecological restoration technology improved soil structure and organic carbon pool similarly to natural forest. The improvement effect of external soil spraying technology was poor.

Abstract:[Objective] The response of soil labile organic carbon components and enzyme activities to natural forest conversion was analyzed in order to provide a scientific basis for predicting regional soil health evolution and environmental change. [Methods] A native evergreen broad-leaved forest and a converted conifer plantation, an orchard, a sloping tillage area, and a paddy with similar geographical background and clear land use history were studied. The responses of labile organic carbon fractions and enzyme activities in topsoil to native forest conversion were investigated using various physical, chemical, and biochemical techniques. [Results] The native forest conversion to an orchard, a sloping tillage area, and a paddy significantly reduced the soil organic carbon content, labile carbon fraction contents, and enzyme activities by 42%—67%, 47%—88%, and 36%—89%, respectively. Notably, the readily oxidizable organic carbon, microbial biomass carbon, and invertase activity experienced the greatest reduction compared with the native forest conversion, sensitively indicating the reduction in soil organic carbon content and its lability. Readily oxidizable organic carbon was, therefore, considered to be a practical index. Reductions in soil labile organic carbon fractions and enzyme activities were lower for the conversion of native forest conversion to plantation than for the native forest conversion to orchard and sloping tillage area, showing the preservation capacity of soil labile carbon in the plantation. The ratio of labile organic carbon to total organic carbon in soil was significantly reduced after the native forest conversion to plantation, sensitively reflecting the reduction in soil carbon quality. [Conclusion] Native forest conversion led to substantial reductions in labile organic carbon quantity, carbon quality, and related enzyme activities in soil, suggesting a degradation of soil biological health and a decline in soil quality.

Abstract:[Objective] The spatial differences and dynamic evolution of carbon ecological security level were analyzed to optimize the overall plan of carbon ecological security in the Yellow River basin (an important “energy basin” in China) in order to objectively reflect the current status and evolution trend of carbon ecological security, and to provide a reference for optimizing the carbon ecological security pattern. [Methods] An evaluation index system for carbon ecological security in the Yellow River basin was constructed under the framework of driving-pressure-state-impact-response (DPSIR) analysis. The technique for order preference by similarity to ideal solution (TOPSIS) model was used to evaluate the level of carbon ecological security, and the spatial-temporal evolution characteristics were analyzed by the kernel density estimation method. [Results] ① Carbon sinks and carbon emissions increased from 2012 to 2021 in the Yellow River basin, and the growth rate of carbon emissions was faster than that of carbon sinks. Carbon sinks were spatially characterized as “higher in the west and lower in the east”, while carbon emissions were “lower in the west and higher in the east”. ② The carbon ecological security level in the Yellow River basin increased over time, from 0.356 in 2012 to 0.639 in 2021. In terms of spatial distribution, the carbon ecological security level in the upstream region was higher than in the middle and downstream regions, and was characterized as “upstream leading, midstream catching up, and downstream surpassing”. In addition, the level of carbon ecological security tended to be good. ③ Based on the kernel density estimation results, the differences in carbon security levels among different regions in the Yellow River basin were gradually narrowing, and were decreasing in the upstream region faster than in the middle and downstream regions. [Conclusion] Based on the current status of carbon ecological security in the Yellow River basin, carbon sink capacity in the upstream region is expected to increase over time, while clean energy industries and technology-intensive industries with high added value should be developed to promote green GDP growth in the middle and downstream regions. In addition, a carbon ecological compensation mechanism should be established to coordinate and resolve cross-regional security issues, and to improve the carbon ecological security level of the entire basin.