Abstract:[Objective] The current status of soil erosion in the Eastern Qaidam Basin was investigated in order to provide a scientific basis for the prevention and control of soil erosion in this region, and for effective environmental management of Qinghai-Tibet Plateau.[Methods] The investigations were conducted in July 2019, 2020,2021 in the Eastern Qaidam Basin, along Delingha, Golmud City, and Dulan County. 77 investigation plots were selected to investigate vegetation, soil, characteristics of soil erosion, and soil and water conservation measures.[Results] Qaidam Basin was dominated by wind erosion. During the crop growing season, there was no obvious wind erosion phenomenon on cultivated land, indicating that the soil and water conservation of crops was remarkable. The average soil wind erosion rates of different land use types followed the order of sandy land> cultivated land> abandoned land> shrub land. Gully erosion was mostly found on the grassland of piedmont alluvial fans and hillsides. Gully erosion on alluvial fans was more serious than on hillsides. Nebkhases were widely distributed and exhibited a diverse mix of species. Nebkhas volume had a strong correlation with plant canopy, and their sand blocking effect was obvious. The main existing problems were soil erosion and rising groundwater level caused by over irrigation of cultivated land, inadequate management of sandy land for planting wolfberry, imperfect soil and water conservation measures, and insufficient investment in soil and water conservation.[Conclusion] The types of soil erosion in Qaidam Basin are complex and diverse. It is recommended that soil and water conservation practices be strengthened, irrigation system maintenance be improved, and soil salinization management and sandfield conservation be strengthened. Thus will effectively ensure the sustainability of land resources in Qaidam Basin.

Abstract:[Objective] The release characteristics of surface sediments in shallow lakes of a city and the influence of organic matter on nitrogen and phosphorus release were analyzed to provide a theoretical basis for eutrophication control of shallow lakes.[Methods] The release characteristics of ammonia nitrogen (NH₄⁺-N) and soluble reactive phosphorus (SRP) were studied in a shallow lake through a release kinetics experiment and a release potential experiment. Results were compared with the release characteristics after organic matter was removed by H₂O₂.[Results] The release rate of nitrogen and phosphorus before and after the removal of organic matter initially slowed down from a faster process, and finally stabilized to reach the maximum release rate. After the removal of organic matter, the release equilibrium time of NH₄⁺-N was shortened, while SRP was almost unchanged. After removing organic matter, the maximum release of NH₄⁺-N was significantly positively correlated with the organic matter content, while SRP had no significant correlation with organic matter.[Conclusion] Various factors influence the release of nitrogen and phosphorus in sediments. Areas rich in higher aquatic plants have a significant inhibitory effect on the release of phosphorus. The higher the content of organic matter in sediments, the higher the maximum release of nitrogen from sediments. The maximum release of phosphorus is affected by factors such as organic matter content, activity, composition, and adsorption, and the combined effects of iron, aluminum, and phosphorus content.

Abstract:[Objective] The effects of aquatic plant remediation technology on rural domestic sewage characteristics were studied in order to provide ideas and reference information for comprehensive and ecological treatment methods in rural areas.[Methods] Using simulated indoor controlled tests, wetland plants of six different ecological types were selected for measurement and analysis of plant biomass, and removal rate, plant accumulation, sediment adsorption capacity of nitrogen and phosphorus. Purification efficiency and removal characteristics of different plants for combinations of nitrogen and phosphorus in wastewater were also studied.[Results] Both single species and combinations of plant species used as an aquatic plant system resulted in a good level of purification of TN, NH₄⁺-N, and TP from sewage. The average removal efficiencies of hydrophyte systems for TN, NH₄⁺-N, and TP were 96.6%, 93.2%, and 95.9%, respectively, and these values were significantly higher than the values observed in the control group. Thalia dealbata in single-crop cultivation grew best. The ratio of aboveground to underground biomass of Iris tectorum was the largest. The relative growth rates of Canna indica in combination planting and Pontederia cordata in single planting were the lowest. Emergent plants had better absorption of nitrogen, and Vallisneria natans had better absorption of phosphorus. The proportion of nitrogen and phosphorus uptake by plants in the total removal capacity of the system was 4.5%-17.1% and 4.1%-13.6%, respectively, and the proportion of nitrogen and phosphorus accumulated by sediment was 11.6%-26.2% and 26.3%-68.4%. Microorganisms and the indirect effects of other plants were the most important mechanisms of nitrogen and phosphorus removal in plant systems.[Conclusion] T. dealbata, I. tectorum, and V. natans and their mosaic combination were ideal wetland plants for purification of rural sewage in Huaibei Plain. Optimizing the combination, number of species, and timing of aquatic plants will be useful for purification of sewage in rural areas.

Abstract:[Objective] The effects of drip irrigation on the distribution of fine roots of five and six years old "107" poplar clones (Populus×euramericana "Neva") in Daxing District forest farm in Beijing City was investigated in order to provide theoretical support for plantation construction under arid sandy land conditions.[Methods] Differences in fine root biomass in different directions, different horizontal distances, and different soil depths due to drip irrigation compared with conventional irrigation were determined from root samples collected by drilling.[Results] The spatial distribution pattern of fine roots was not changed by drip irrigation. Within 50 cm from the trunk (in the horizontal direction), and within the 0-40 cm soil layer (in the vertical direction), fine roots were distributed intensively. In different directions, fine roots were distributed in the following order:between plants > diagonal direction > between rows. Growth and distribution of fine roots were mainly affected by the range of the wetting zone of drip irrigation. The distribution of fine root biomass in the inter-plant direction was significantly different from the diagonal direction and the inter-row direction. The biomass of fine roots under drip irrigation was significantly different from the biomass under conventional irrigation (p<0.01).[Conclusion] There were more fine roots in poplar plantations under drip irrigation than under conventional irrigation. The increased number of fine roots can make full use of underground resources, promote the growth of trees, and improve forest land productivity.

Abstract:[Objective] The influence of litters on the hydrological effect of sandy land in the wind-water erosion crisscross region of the Loess Plateau was explored in order to provide a theoretical basis for the evaluation of eco-hydrological benefits after the implementation of the ‘Grain for Green’ project in this area.[Methods] Litter-covered sites of Populus simonii, Caragana korshinskii, and Bothriochloa ischaemum were selected as the research objects, and bare sandy land was taken as the control in order to reveal the effects of litter cover on water conservation capacity in sandy land by using the entropy weight method.[Results] ① The maximum water holding rate, maximum retention rate, effective retention rate and maximum hygroscopicity rate of litter followed the order of B. ischaemum > P. simonii > C. korshinskii. The water holding capacity and retention capacity of litters followed the order of P. simonii > C. korshinskii > B. ischaemum. ② Litter cover reduced the soil bulk density, but increased total porosity, saturated water holding capacity, capillary water holding capacity, and mean infiltration rate. ③ The comprehensive evaluation value of water conservation capacity followed the order of litter-covered sites of C. korshinskii (0.889) > litter-covered sites of P. simonii (0.484) > litter-covered sites of B. ischaemum (0.228) > bare sandy lands (0.038). ④ Stable infiltration rate, soil effective water holding capacity, and soil non-capillary porosity accounted for the highest water conservation function weights, which accounted for 15.3%, 14.8%, and 14.8%, respectively.[Conclusion] Litters effectively improve the hydrology of sandy land. The results of this study suggest that shrubs be planted to optimize water conservation capacity, and that trees and herbs can be planted together.

Abstract:[Objective] The response of soil water content to the change of the flow rate and fine roots of Hippophae rhamnoides in the feldspathic sandstone area was studied in order to provide reference for the rational cultivation and management of H. rhamnoides in the arid and water-deficient area.[Methods] The stem sap flow of H. rhamnoides plantations in Wenshui Township, Zhungeer Banner, Ordos City was monitored by using Granier stem sap flow measurement system for a long time, and the fine roots of plants and the soil moisture around the fine roots were measured at the same time, and the response of stem fluid flow and fine root changes to soil moisture in the growing season (September and October) of the H. rhamnoides plantation were analyzed using correlation analysis.[Results] ① The soil water content and the flow rate of H. rhamnoides were lower in the early period (June to July), increased in the middle and late period (July to September), and decreased rapidly in the late period (September and October). The growth rate of fine roots of seabuckthorn was higher in the middle and late period, and lower in the early and late period. ② The variation trend of soil water content and sea-buckthorn fluid flow rate in each month during the growing season was consistent, and the descending order was as follows:August >July >September > June >October. ③ There was a significant positive correlation between the change of soil water content and the flow rate of sea-buckthorn (p<0.01). With the increase of soil water content, the flow rate of sea-buckthorn gradually increased. The growth rate of fine roots of sea-buckthorn was positively correlated with the flow rate of sea-buckthorn (p<0.05). The faster the growth rate of fine roots of sea-buckthorn was, the higher the flow rate of sea-buckthorn was. On the contrary, the slower the growth rate of fine roots of sea-buckthorn was, the lower the flow rate of sea-buckthorn was. There was a significant positive correlation between soil water content and fine root growth rate (p<0.01). With the increase of soil water content, the fine root growth rate of seabuckthorn gradually increased.[Conclusion] The change of H. rhamnoides sap flow is the main factor affecting the change of soil moisture in feldspathic sandstone area, and the change of fine root of H. rhamnoides also affects the change of soil moisture. Relatively speaking, the change of sap flow of H. rhamnoides is greater than that of fine root of H. rhamnoides. Transpiration is the main factor affecting soil moisture in feldspathic sandstone area.

Abstract:[Objective] The impact of vegetation restoration on the water cycle of Beichaun River basin was studied and the evolution trend of water resources in the basin under the conditions of vegetation restoration was analyzed in order to provide data support for guiding scientific vegetation restoration in arid and semi-arid areas.[Methods] The evolution trend of water cycle elements at the basin scale was analyzed based on the vegetation cover change and long-term meteorological and hydrological data at Beichuan River basin in Qinghai Province. The influence of vegetation restoration on the evolution of key water cycle elements was analyzed.[Results] Vegetation coverage in the hills and mountains of Beichuan River basin had increased rapidly since the 1980s, with an average increase of 14.98% and a maximum increase of 52.2% from 2000 to 2019. From 1956 to 2019, the annual precipitation in the basin was relatively stable, but the annual runoff showed a small decreasing trend, with an average decrease of 0.16 billion m³/10 yr. Increasing ecological water consumption caused by vegetation restoration was the main reason for decreasing runoff. Vegetation restoration had changed the spatial and temporal distribution of precipitation in the basin. In space, more precipitation was used for ecological consumption in the basin, which reduced the water supply to downstream regions. In time, more precipitation participated in the soil water-groundwater cycle, and prolonged the drainage period outside the basin. Vegetation restoration significantly reduced meteorological factors such as surface wind speed, water evaporation, and drought index.[Conclusion] Runoff in Beichuan River basin has decreased due to the influence of vegetation restoration. Additionally, ecological water consumption and the proportion of water in the cycle of precipitation-soil water-groundwater has increased, water conservation capacity has continued to increase, and semi-arid climate conditions have improved.

Abstract:[Objective] The ability of a salt lake protection system to protect against wind and sand damage quantitatively and the changes to surface erosion and deposition induced by the system were described in order to reveal the wind-proof and sand-resistant action law of the protection system. The purpose of this study is to provide data support for the evaluation of the protection effect of the Jilantai Salt Lake protection system, and to provide a theoretical basis for sand damage control in the sandstorm area and desert salt lake in Northwest China.[Methods] The Jilantai Salt Lake protection system was chosen as the research object. Sand transporting (at 0-30 cm height) and surface erosion sediment intensity (monthly) were observed in situ by field positioning monitoring in different parts of the Jilantai Salt Lake protection system.[Results] ① The wind speed at 2 m height from the moving sand ridge to the center of the salt lake passed through three phases (attenuation, rapid attenuation, recovery). The wind speed from the Nitraria tangutorum shrub to the saline-alkali beach decreased by 70%~90% compared with the moving sand ridge. ② The sediment discharge from N. tangutorum to the center of the salt lake passed through three states (sharp decrease-decrease-slow increase), and was 83.89%~94.90% lower than the sediment discharge of the moving sand ridge. ③ The effect of the protection system on wind prevention and sand resistance from the two main harmful wind periods was obvious. Wind speed and sediment discharge decreased by 98.71% and 91.79%, respectively, compared with the moving sand ridge. In addition, the effect on wind and sediment prevention for the northwest wind direction was better than that for the southwest wind direction. ④ The surface showed sedimentation from N. tangutorum to the center of the salt lake from June to September, and the net erosion intensity could be reduced by up to a maximum of 157.04% compared with the moving sand ridge.[Conclusion] Although the protection system was affected by season and wind direction, the windbreak and sand-blocking effects still maintained a good state, and its blocking effect on wind-sand flow can change the state of the surface from wind erosion to sedimentation, thereby reducing wind speed and sediment discharge by more than 90%, and thus effectively avoiding sand accumulation on the salt lake surface.

Abstract:[Objective] Groundwater recharge beneath a village pond in the loess tableland was quantitatively studied to provide a theoretical basis for the sustainable utilization of groundwater resources in the study area.[Methods] Soil moisture, and stable hydrogen and oxygen isotopic composition of soil water in deep loess profiles (DLP) beneath a village pond and cropland in Changwu loess tableland were measured. The isotopic tracing technique was used to estimate groundwater recharge beneath the village pond.[Results] ① The average soil moisture of DLP beneath the village pond was 25.5%, which was greater than that of cropland (20.6%). ② The values of δD and δ¹⁸O of soil water were -117.83‰~-56.66‰ and -16.63‰~-7.72‰, respectively, beneath the village pond, and -81.76‰~-52.03‰ and -10.64‰~-6.35‰ beneath the cropland, respectively. The effect of evaporation on soil water beneath the pond was weaker than it was in cropland, and the stable isotopes of soil water were more negative with larger variation in isotopic composition. ③ The isotope profile of soil water beneath the village pond retained the isotopic signals of large precipitation events, indicating that groundwater was recharged by piston flow beneath the village pond, and had an infiltration velocity of 0.26 m/d. The mean annual recharge rate of groundwater was 134 mm/yr in the pond catchment, accounting for 23.1% of the annual precipitation.[Conclusion] Village ponds are an important recharge source for groundwater in the Loess Plateau. Thus, efforts should be made to strengthen the protection, restoration, and reconstruction of ponds to ensure the continuous recharge and utilization of groundwater in the Loess Plateau.

Abstract:[Objective] Effects of different plants and improvement methods on the nitrogen conversion rate of reconstructed soil were studied in order to provide a theoretical basis for improving the available nitrogen content of reconstructed soil at mining areas.[Methods] Stripping material from the Zhahanur open pit coal mine in Tongliao City, Inner Mongolia was used as the matrix to prepare reconstructed soil. Chicken manure and self-made amendments were used to improve the soil. Four types of plants were selected to study the effects of these two factors on the existing form of inorganic nitrogen, net mineralization rate, net ammonification rate, and net nitrification rate.[Results] Nitrate nitrogen was the main form of inorganic nitrogen in reconstructed soil. The effects of modifiers, plants, and their interactions on the net mineralization rate, net ammonification rate, and net nitrification rate of reconstructed soil nitrogen were very significant. The content and net nitrification rate of ammonium, nitrate, and nitrite nitrogen in reconstructed soil was improved significantly by self-made amendments. Medicago sativa significantly improved nitrate nitrogen content and the net mineralization rate of nitrogen in reconstructed soil. The net mineralization rate of nitrogen in reconstructed soil was the highest at 90 days.[Conclusion] Within 90 days after planting, the existing form of inorganic nitrogen in reconstructed soil was transformed from ammonium nitrogen to nitrate nitrogen. Adding self-made amendments improved the content of inorganic nitrogen in reconstructed soil, and increased net ammonification rate, net nitrification rate, and net mineralization rate of nitrogen in reconstructed soil at mining areas.

Abstract:[Objective] The hydrogen and oxygen isotope characteristics of plant water under different water gradients were analyzed and compared in order to provide a theoretical basis for the selection of suitable species for ecological protection, erosion control, and sand control in the Yellow River basin.[Methods] Using hydrogen and oxygen stable isotope technology, based on the HYSPLI4 air mass trajectory model and the Bayesian mixed model MixSIAR, the potential water utilization efficiency of dominant plants under different water gradients along the banks of a major tributary of the Yellow River, was analyzed, and water utilization strategies of different plants were then proposed.[Results] The atmospheric vapor was mainly affected by the local evaporation air mass and northwest monsoonal transport during the sampling period. Shallow soil water (0-30 cm) was the main water source for plants in the floodplain. On terraces of the river valley, herbaceous plants mainly used shallow and middle soil water (0-70 cm), while shrubs and tall herbs used water from deeper soil layers (70-100 cm). The phenomenon of ecohydrologic niche separation between plants was apparent.[Conclusion] When water is scarce, shrubs are more competitive because of their water use patterns. Shrubs are suitable species for ecological protection, erosion control, and sand control in the Yellow River basin.

Abstract:[Objective] In order to provide a scientific basis for more effectively guiding the sustainable development of soil resources and ecological environmental protection in the loess region of Southern Ningxia Hui Autonomous Region, soil particle size characteristics under different vegetation recovery patterns were studied.[Methods] Field standardized soil samples (0-100 cm) were collected, and 216 samples from nine different vegetation restoration methods (Prunus armeniaca forest, Amygdalus davidiana forest, Hippophae rhamnoides forest, Caragana korshinskii forest, C. korshinskii×P. armeniaca forest, P. armeniaca×H. rhamnoides forest, dam land, alfalfa land, and abandoned land) were measured with a Mastersizer 3000 laser particle size analyzer. The average particle size (M_Z), standard deviation (δ), skewness (SK), and kurtosis (K_G) were calculated by the Fokker and Ward formula.[Results] ① Under different vegetation recovery patterns, the main particle size components were silt (0.002~0.05 mm) and very fine sand (0.05~0.1 mm), and the proportion of silt content in each particle size classification was the largest. The contents of clay, coarse sand, very coarse sand, and medium sand in different vegetation restoration methods tended to be stable, and changed little with increasing soil depth. The content of silt, very fine sand, and fine sand fluctuated greatly with increasing soil depth, and each layer showed different trends. ② The variation of the coefficient of variation of each particle size was basically the same under different vegetation restoration methods. The coefficient of variation of clay was the highest, followed by sand and silt. ③ The average soil particle size followed the order of P. armeniaca×C. korshinskii forest > H. rhamnoides forest > A. davidiana forest > C. korshinskii forest > P. armeniaca forest > alfalfa land > P. armeniaca×H. rhamnoides forest > abandoned land > dam land. The sorting ability of abandoned land, A. davidiana forest, and C. korshinskii forest was better than that of other sites, with H. rhamnoides forest being the worst.[Conclusion] Soil particle size distribution in different vegetation restoration methods was mainly affected by utilization mode, vegetation type, and human activity disturbance.

Abstract:[Objective] Variation of soil hydraulic characteristics under different forest types were studied to provide a scientific basis for regional ecological landscape construction and selection of water resource conservation forests.[Methods] Different forest types (bamboo forest, chinese fir forest, mixed forest) and terraced fields were selected as the research objects at a Longji terraced field in Guangxi Zhuang Autonomous Reion. The main soil properties were measured in different soil layers (10, 20, 40, 60 cm) to sduty soil hydraulic characteristics and their influencing factors.[Results] ① The soil texture of Longji terraces was silty loam. The clay content of the soil had significant differences, but the silt and sand content had no significant differences in different layers. ② Soil bulk density differences in different layers of chinese fir forest and mixed forest were not significant, but the soil bulk density in the lower layer of bamboo forest and terraced field was significantly higher than that in the upper layer. The soil capillary porosity, total porosity, and field water holding capacity followed the order of mixed forest >chinese fir forest > bamboo forest > terraces. ③ The soil permeability of bamboo forest was the greatest, followed by chinese fir forest and mixed forest, and was lowest in the terraced fields. ④ Under the same soil suction, the volumetric soil moisture content of mixed forest and chinese fir forest were similar, and the soil water holding capacity was greater than that of bamboo forest and terraced field. Soil bulk density and porosity (capillary porosity and total porosity) were the main factors influencing soil permeability and water holding capacity. The saturated water conductivity had a significant negative correlation with soil bulk density and a significant positive correlation with porosity. The soil water characteristic curve fitting parameter θ_s was significantly negatively and positively correlated with soil bulk density and porosity (capillary porosity and total porosity), respectively, and α was significantly positively correlated with soil porosity.[Conclusion] Bamboo forest had the greatest soil permeability, but the lowest soil water-holding capacity. Both chinese fir forest and mixed forest had large soil water-holding capacity, and can be instrumental in promoting good water conservation.

Abstract:[Objective] The effects of optimizing fertilization on improving soil quality and crop yield of newly cultivated land were studied in order to provide a theoretical basis for the establishment of reasonable optimized fertilization recommendations and the sustainable development of newly reclaimed cultivated land in the Loess Plateau.[Methods] The improvement effects of organic fertilizer (OF), organic fertilizer combined with chemical fertilizer (NP), and conventional fertilization (CF) on soil organic matter (SOM), soil aggregate distribution, structure stability, and corn yield in newly reclaimed cultivated land were evaluated using pot experiments.[Results] SOM content of newly reclaimed cultivated land was the lowest (7.08 g/kg) under CF, with low aggregate content and poor structural stability. OF and NP significantly increased SOM content of the newly reclaimed cultivated land (p<0.05) compared with CF. The particle size>0.25 mm aggregate concentration (R_0.25) and aggregate stability were also significantly improved. The OF treatment had the greatest effect on improving the quantity and stability of soil aggregates. In the 0-10 cm soil layer, the SOM content under OF and NP treatments was 12.67 g/kg and 11.79 g/kg, respectively, which was 46.2% and 36.1% higher than SOM under CF. Moreover, the mean weight diameter (MWD), geometric mean diameter (GMD) and R_0.25 values of water-stable aggregates under OF were 62.5%, 21.4%, and 148.3% higher, respectively, than those values under CF, and the fractal dimension (D) was 1.7% lower than under CF. Meanwhile, the MWD, GMD, and R_0.25 values under NP were 18.8%, 3.6%, and 40.9% higher, respectively, than those values under CF, and the D value was 0.4% lower than under CF. In the 10-20 cm soil layer, the SOM content and the quantity and structural stability of soil aggregates under OF and NP were also increased to a certain extent. The MWD, GMD, and the SOM content showed significant positive correlations (p<0.001).[Conclusion] Optimizing fertilization is an effective measure for improving soil structure stability, fertility retention characteristics, and land productivity in newly reclaimed cultivated land.

Abstract:[Objective] The restoration of soil and plant communities in a mining area after the implementation of ecological restoration measures was investigated in order to provide a basis for the evaluation of restoration measures in the mining area.[Methods] The study was conducted in the gold mine ecological restoration area at Ungulated Wildlife Nature Reserve in the Kalamaili Mountain of Xinjiang Wei Autonomous Region. The vegetation characteristics, plant community diversity, and soil physical and chemical properties were investigated and analyzed through sampling methods and laboratory experiments.[Results] Soil pH value, electrical conductivity, organic matter, total nitrogen, and total potassium in the gold mine ecological restoration area were generally lower than in the primary control area. There were fewer plant species, and the Chenopodiaceae plants from human sowing were dominant. The plant community diversity index was low and was closely related to the diversity index in the native control area. The plant community was mainly affected by the contents of soil organic matter, available phosphorus, and rapidly available potassium.[Conclusion] The soil physical and chemical properties and plant communities of Qinghe Dashagou and Fuyun Dashagou improved significantly after the ecological restoration measures, and the restoration effect was significant. Due to the short time available for recovery observations in this study, there were few plant species, low community stability, and generally low content of soil physical and chemical properties at all gold recovery areas. Therefore, these areas require still more time to recover.

Abstract:[Objective] The spatio-temporal dynamic changes of vegetation in Tongren City, Qinghai Province (located at the westernmost end of the Loess Plateau and the bordering Qinghai-Tibet Plateau) were studied in order to provide references for ecological protection and management of the transition zone between the two plateaus.[Methods] The characteristics of dynamic vegetation changes in space and time from 2000 to 2019 were investigated using linear trend regression and the Hurst index based on MODIS-NDVI data. Also, a preliminary analysis of relationships between NDVI changes and land uses and altitudes was conducted, and future trends in NDVI variation were predicted.[Results] ① NDVI values in Tongren City showed a growth rate of 0.027/10 yr over the past 20 years. Areas with high NDVI values increased significantly, and were mainly located in the eastern and western mountainous areas. The areas with NDVI values varying between 0.8 and 1.0 increased from 388.63 km² in 2000 to 1 066.92 km² in 2019. ② NDVI increased over an area of 2 925.21 km², accounting for 84.42% of the city's area. This area was widely distributed in the Longwu River valley and the surrounding mountainous area, including 626.13 km² of forest land and 2 094.11 km² of grassland. ③ The area where NDVI decreased was 539.79 km², accounting for 15.58% of the city's area. Most of this area was located in the high-altitude area in the western and southern mountainous area, while a small part of the area was in the Longwu River valley. Taking the lowest altitude of freezing and thawing erosion (3 583 m) as a limit, the area of decreasing NDVI was located above 3 583 m, and accounted for 70.93% of the total area that showed decreasing NDVI. ④ In the future, NDVI will generally continue to increase, with the area of increasing NDVI accounting for 79.17% of the city area, while the area where NDVI will decrease will account for 13.13% of the area of the city.[Conclusion] During the past 20 years, NDVI has generally increased in Tongren City, with high-coverage vegetation increasing significantly. The areas where NDVI decreased were mainly located in high-altitude areas. In the future, NDVI values for Tongren City will continue to increase as a whole, but some areas will still show decreases in NDVI.

Abstract:[Objective] The spatial distribution of soil erosion in the rich and coarse sediment areas of the Yellow River basin was studied in order to provide data support and scientific suggestions for soil erosion control, ecological environmental protection, and high-quality development in the Yellow River basin.[Methods] Dynamic changes of soil and water loss in rich and coarse sediment areas of the middle reaches of the Yellow River basin were analyzed based on dynamic monitoring of soil erosion in 2020 and the results of the national remote sensing surveys of soil erosion in China in 1985 and 1999.[Results] ① The area of regional soil and water loss decreased by 43.22%, the area of high-intensity soil and water loss decreased by 90.80%, and the status of soil erosion has been improved significantly over time. The changes in 1985-1999 were relatively small, while the changes in 1999-2020 were relatively large. ② The intensity of soil and water loss decreased in both periods. The decrease in 1999-2020 was significantly greater than in 1985-1999, and high-intensity soil erosion decreased significantly. In 1985-1999, the area of severe erosion mainly decreased, while in 1999-2020, the areas classified as intensive, extremely intensive, and severe erosion decreased significantly.[Conclusion] The main driving forces for the improvement of the ecological environment in the study area were the strengthening of the supervision and management of regional soil and water conservation, coordinated promotion of preventive protection and comprehensive management of soil and water conservation, economic and social development, environmental protection, and ecological policy guidance. Although the increasingly serious conditions resulting in soil and water loss in the Loess Plateau have been controlled, the region is still considered to be under the most severe soil erosion threat in China. It is still necessary to continue to take appropriate measures for the protection of the ecological environment.

Abstract:[Objective] The distribution characteristics of non-point source pollution in the Zhaohe small watershed in different periods were studied in order to identify the key source areas in order to provide a reference for pollution control and clean small watershed construction.[Methods] The distribution characteristics of non-point source pollution of the basin in the current year and planning year were simulated by establishing a watershed non-point source pollution control model. At the same time, the load per unit area index method (LPUAI) was used to identify the key pollution sources in the basin, and the reduction effects of different non-point source pollution control measures on main pollutants were predicted.[Results] In the absence of non-point source pollution control measures, the nitrogen and phosphorus non-point source pollutants in the planning year of the basin increased by 45.3% and 8.0%, respectively, compared with the current year. Xianhe River, Shicao River, Peihe River, Shengqiao River, and Huanwei River sub-basins were the key areas of non-point source pollution in the basin. Non-point source pollution can be effectively controlled by setting reasonable engineering measures and farming management measures.[Conclusion] Appropriate non-point source control measures can help to reduce the nitrogen and phosphorus pollution load in the watershed. Cultivation management measures plus engineering measures are the best management measures, which can effectively control the non-point source pollution of total nitrogen and total phosphorus in the watershed.

Abstract:[Objective] Runoff responses to climate changes in Lanjiang River basin were analyzed in an effort to provide a scientific basis for improving sustainable water resources, flood control, and drought resistance.[Methods] The applicability of the HEC-HMS hydrological model in this basin was determined by calibrating the processes of daily rainfall and runoff, in addition to six processes of rainstorms and floods from 2015 to 2018. Based on the statistical downscaling model (SDSM), the climate data of three climate change scenarios (RCP 2.6, RCP 4.5, and RCP 8.5) under the CANESM2 model from 2030 to 2100 were downscaled for generating future daily precipitation time series at six meteorological stations in Lanjiang River basin in order to predict the runoff in response to future climate changes.[Results] The average correlation coefficients of the HEC-HMS model for floods and daily runoff simulations were 0.89 and 0.77, respectively. The average efficiency coefficients of the HEC-HMS model for floods and daily runoff simulations were 0.86 and 0.76, respectively. Precipitation in the study area under the RCP2.6 scenario decreased by 0.82% compared with the base period (2015-2018), and increased by 6.18% and 18.17% under the RCP4.5 and RCP8.5 scenarios, respectively. Average annual runoff under the RCP2.6, RCP4.5, and RCP8.5 scenarios increased by 17.00%, 26.22%, and 41.93%, respectively, compared with the base period.[Conclusion] The HEC-HMS model is applicable for runoff simulation in the Lanjiang River basin. In the future, runoff in the Lanjiang River basin will show a significant upward trend, and increase synchronously with the enhancement of radiation forcing. When radiative forcing increases to 8.5 W/m², runoff will increase by 49.49 m³/s every 10 years, and predictably, the average annual runoff will reach 1 101 m³/s at the end of the 21st century. Additionally, annual runoff will fluctuate sharply, runoff in the flood season will account for a higher proportion of the year, and drought and flood events will tend to be frequent.

Abstract:[Objective] The spatial and temporal variation characteristics of rainfall erosivity were analyzed in order to provide data support for regional soil loss monitoring and soil and water conservation.[Methods] Based on daily rainfall data from 71 rainfall stations in Yimeng Mountain region and its surrounding areas from 1980 to 2018, the temporal and spatial variation trend of rainfall erosivity was analyzed using the daily rainfall formula, M-K test, geostatistical analysis, and so on.[Results] ① Rainfall and erosive rainfall had a moderate monthly concentration (FI>53, CI>0.17), rainfall erosivity had a high monthly concentration (FI=399.88, CI=0.24), and the annual variation curve was unimodal, with the peak occurring from July to August. ② The annual average rainfall in the study area was 744 mm, and the annual average rainfall erosivity was 3 657 MJ·mm/(hm²·h·a), showing a spatial distribution trend of low in the north and high in the south, low in the west and high in the east. ③ The interannual variation of rainfall erosivity was moderate, and the overall trend was not significant. Spatially, there was a significant upward trend in the northwest (z>1.96) and an insignificant downward trend in the south (z<0.05).[Conclusion] The increase in rainfall erosivity will increase the risk of regional soil and water loss. Therefore, comprehensive prevention and control of soil and water loss should be strengthened so as to realize the sustainable development of the ecological environment and economic society.

Abstract:[Objective] Change characteristics of the primary ecosystem services in Horqin sandy land under the implementation of ecological construction projects were studied in order to provide a scientific basis for future ecological protection and construction in this area.[Methods] The temporal-spatial changes of carbon sequestration, water source conservation, and soil conservation in this region from 2001 to 2018 were evaluated by using existing ecosystem service assessment methods.[Results] ① The land use types in Horqin sandy land were mainly farmland, forestland, and grassland. During the implementation of the ecological construction project, the area of forestland and farmland increased by 8 448 km² and 3 280 km² respectively, but the area of grassland decreased by 12 639 km². ② Carbon sequestration in this region increased steadily. Carbon sequestration of forestland and farmland increased, while that of grassland decreased. However, carbon sequestration of grassland was still the highest. ③ The amount of water conservation of this region first increased and then decreased slightly, but the amount of water conservation in forestland continued to increase. ④ The amount of soil conservation in Horqin sandy land increased continuously, with an increase of about 1.38×10⁷ t, with forestland showing the largest increase. The spatial distribution of soil conservation was obviously limited by the terrain, with the total amount of soil conservation being highest in the west and lowest in the east.[Conclusion] The ecological construction projects in Horqin sandy land have produced good effects and significant ecological benefits.

Abstract:[Objective] By optimizing the spatial allocation of land resources, the efficiency of land use can be improved, and the rational distribution of various industries and infrastructure can be promoted in order to provide a theoretical basis for the comprehensive development of the regional social economy.[Methods] The study was conducted at Kaysone Phomvihane City in Laos. GIS spatial analysis technology, logistic regression analysis, and the CLUE-S model were combined to carry out the research on the spatial optimization of land resources. Under the constraints of spatial suitability and quantity structure, model calculations were performed on the basis of land demand, limiting factors, conversion rules, and spatial characteristics to optimize the spatial allocation of land resources in Kaysone Phomvihane City.[Results] The urban construction land and paddy fields expanded to suitable areas on the original basis. The relatively sparse forestry land was developed and utilized, resulting in a moderate reduction in area. Other land types had small changes in quantity and space.[Conclusion] Urbanization and agricultural development can provide the foundation and support for the economic development of Kaysone Phomvihane City. At the same time, ecological protection should be taken into account to promote coordinated and sustainable use of land resources.

Abstract:[Objective] The temporal and spatial characteristics of soil erosion in the Yellow River alluvial area of Northeast He'nan Province in 2019 were analyzed in order to provide reference data for regional soil erosion control, ecological environment construction, and economic and social development.[Methods] The study was conducted in Lankao County. The multi-source remote sensing images were used as the basic data to calculated wind erosion and water erosion modulus using a wind erosion model and the CSLE model. Soil erosion and its influencing factors for each half-month in 2019 were studied, and the characteristics of soil erosion in 2019 were comprehensively analyzed.[Results] ① The half-month U values changed over time, following an "M" shape. The values were higher during the 3rd-9th and the 21st-22nd half-month periods. The half-month value of W showed a "wave-like" change, where values were higher during the 13th-18th half-month periods. The values of R and the average values of B with respect to forest, garden, and grass first increased and then decreased with time during 2019; the former had higher values in the 9th-16th half-month periods, and the latter had higher values in the 12th-18th half-month periods. ② The half-month wind erosion modulus in Lankao County showed a "wave-like" shape. Wind erosion was strong in the 4th-9th and the 21st-22nd half-month periods. The cumulative wind erosion modulus for the entire year was in the range of 0-5 186.31 t/(km²·yr), with an average value of 153.26 t/(km²·yr). The wind erosion modulus of Yifeng Township and Zhangjun Tomb Town was relatively high, and these high values were mostly located on irrigated land and mining land. ③ The half-month water erosion modulus in Lankao County first increased and then decreased with time. During the 12th-18th half-month periods, water erosion was relatively strong. The annual cumulative water erosion modulus ranged from 0-8 028.86 t/(km²·yr), and the average value was 9.54 t/(km²·yr). There were strong water erosion areas in Dongbatou Township and Chengguan Town, mainly on mining land. ④ Soil erosion in Lankao County in 2019 occurred in 17 half-month periods, accounting for 70.83% of the year. During the 4th-9th half-month periods, Lankao County had the largest soil erosion area, and all of the erosion in this area was wind erosion. The area of soil erosion was 271.66 km² in 2019, accounting for 24.34% of the county's area. Erosion was mainly due to mild wind erosion, accounting for 96.83% of the area of soil erosion. Wind erosion mainly occurred in Yifeng Township, Zhangjun Tomb Town, Guying Town, and Dongbatou Township. Water erosion mainly occurred in Yifeng Township.[Conclusion] Soil erosion in Lankao County in 2019 mainly occurred in the 4th-9th and 21st-22nd half-months, and was mainly in the form of mild wind erosion, mainly distributed in Yifeng Township, Zhangjun Tomb Town, Guying Town, and Dongbatou Township. Future efforts to monitor and prevent soil erosion should focus on erosion occurring on irrigated land and mining land during these time periods.

Abstract:[Objective] Representative purple soil and zonal yellow soil in Southwest China were selected to analyze their spectral information and to estimate soil moisture content in order to provide a method basis for rapid soil moisture monitoring in Southwest China.[Methods] Different soil moisture content levels were established in two soil types in the laboratory, and spectral reflectance was measured by using a ground surface spectrometer. The hyperspectral characteristics were compared and analyzed, and the characteristic bands were extracted by various mathematical transformations and correlation analysis. Hyperspectral estimation models of soil moisture were then constructed by stepwise multiple linear regression (SMLR) and BP neural network (BPNN).[Results] ① The spectral reflectance of both purple soil and yellow soil decreased as soil moisture content increased, and the spectral reflectance of purple soil was lower than that of yellow soil under the same soil moisture content. ② The effect of soil moisture content on the reflectance of infrared wavelengths (760-2 500 nm) was stronger than the reflectance of visible wavelengths (380-760 nm), and there were obvious water absorption valleys near 1 400, 1 900 and 2 200 nm. ③ There was a strong correlation between spectral reflectance and soil moisture content of purple soil and yellow soil after mathematical transformation. ④ The soil moisture prediction model based on BPNN was superior to SMLR.[Conclusion] The BPNN model was the best model for estimating soil moisture content of purple soil and yellow soil in Southwest China. The BPNN model can quickly and accurately obtain soil water status of purple soil and yellow soil.

Abstract:[Objective] The evolution characteristics of social-ecological-production landscape resilience in areas along the mainstream of the Yellow River in He'nan Province from 2000 to 2018 was quantitatively determined in order to guide the coordinated development of social life, ecological resources, the environment, and agricultural production activities in this region.[Methods] We constructed the social-ecological-productional landscape resilience (SEPLR) assessment framework to quantitatively study the evolution characteristics of the social-ecological-productional landscape resilience in He'nan Province along the mainstream of the Yellow River from 2000 to 2018. An ordered weighted average method was used to set up scenario preferences and to draw a map of resilience prediction under the guidance of various policies.[Results] ① Based on the overall characteristics, the SEPLR value of the areas along the mainstream of the Yellow River in He'nan Province from 2000 to 2018 varied from 0.47 to 0.52, presenting an upward trend. The spatial differences between cities kept expanding gradually. ② From the perspective of evolution characteristics, social system resilience and ecosystem resilience increased slowly, fluctuating between 0.14~0.65 and 0.08~0.30, respectively, and the production system resilience slightly fluctuated between 0.12~0.31. In terms of space, SEPLR and its subsystems overall presented a distribution pattern of "being strong in the center and weak on both sides", and the hierarchical structure was concentrated.[Conclusion] For cities along the Yellow River in He'nan Province, the resilience of "ecology first" was the highest of the four policy scenarios of "maintaining the status quo" "ecology first" "development first" and "agriculture first". In the future, the high-quality development of the Yellow River basin should be guided by the"ecology-first" policy.

Abstract:[Objective] The leading functions of forest ecosystem services in Liaoning Province were evaluated, and their significance and feasibility as a nature-based solutions were analyzede in order to provide a theoretical basis for exploring nature-based solutions (NbS) suitable to conditions in China.[Methods] Based on the second-category survey data of forest resources in Liaoning Province in 2017, in accordance with the National Standard of the People's Republic of China "Specifications for assessment of forest ecosystem services" (GB/T38582-2020), the distributed measurement method was used to assess and evaluate the four leading service functions (i.e., green reservoir, green carbon pool, environmental oxygen bar pool, and biodiversity gene pool), and their contributions to solving social challenges were discussed.[Results] The monetary values of the four leading functions of the province were 1.71×10¹¹,8.24×10¹⁰,3.40×10¹⁰,and 9.69×10¹⁰ yuan/year, respectively. The distribution pattern of the services was mountainous areas in Eastern Liaoning>Northwestern Liaoning>coastal areas of central and Southern Liaoning. Dandong, Fushun, and Benxi had higher service functions, and Shenyang, Jinzhou, and Panjin cities had lower service functions.[Conclusion] In the context of global climate change and the increasingly urgent time to achieve the sustainable development goals, the connotation of NbS coincides with the contribution of ecosystem services to human well-being. The full use of various ecosystem services provided by forests can help solve problems related to climate change, biodiversity loss, and environmental degradation.

Abstract:[Objective] The temporal and spatial distribution of impervious surface ratio was analyzed in order to determine the development potential of the city, in order to provide a reference for urban plannings, such as soil and water conservation, and subsequent development.[Methods] Eighteen Landsat 3/5/7/8 images of Shenzhen City during nine periods from 1979 to 2020 were selected and used to extract the proportion information of impervious surface as the reference data. The spatiotemporal distribution of impervious surface in Shenzhen City was analyzed based on the mean center of impervious surface, standard deviation ellipse, and landscape pattern index.[Results] ① The percentage of impervious surface in Shenzhen City from 1979 to 2020 showed an increasing trend. The rate and intensity of growth was highest from 1990 to 2010, and then gradually slowed. ② Due to the unbalanced development of Shenzhen City, from 1979 to 2000, the development center moved to the northest. From 2000 to 2010, the center moved to the northwest. After 2010, the center moved in the east-west direction. In general, the development direction of Shenzhen City was mainly from east to west. ③ The change of landscape pattern showed that the landscape distribution of impervious surface at different levels was becoming more and more balanced, and the distribution trend gradually moved from fragmentation to higher and higher concentration. Connectivity gradually increased over time.[Conclusion] Different stages of impervious surface growth exhibited different temporal and spatial distribution patterns, and impervious surfaces of different densities had their own characteristics. Reducing the degree of aggregation of high-density impervious surfaces has a positive impact on future development of the city.

Abstract:[Objective] The health of the ecosystem of the Yangtze River economic belt, one of the major strategic development regions of China, was diagnosed in order to provide a scientific basis for promoting the coordinated development of the regional ecology and economic society.[Methods] ① The urban agglomerations of the Yangtze River economic belt were taken as the research area. Starting from the five dimensions of vitality, organizational structure, resilience, ecosystem services, and population health, an ecosystem health diagnostic index system for the Yangtze River economic belt was constructed. ② According to ecosystem health standards, the area was divided into the following five levels:sickness, unhealthy, sub-healthy, healthy, and very healthy. Diagnostic index weights were then determined based on the entropy weight method. ③ A normal cloud model was constructed to comprehensively diagnose the health of the ecosystem of the Yangtze River economic belt in 2000, 2009, and 2018.[Results] From 2000 to 2018, the ecosystem health level along the Yangtze River economic belt had been improved at both the overall level and at the provincial and municipal levels. At the end of 2018, the ecosystem health status of the entire study area had generally tended to the sub-health level.[Conclusion] Population density, per capita disposable income, per capita arable land area, and per capita regional GDP were the main factors affecting the ecosystem health of the Yangtze River economic belt. Therefore, it is particularly important to give attention to population development planning, increase per capita disposable income, strictly observe the red line of arable land, give attention to the scientific and healthy expansion of cities, and couple the relationship between economic development and ecological protection.

Abstract:[Objective] The synergistic development of the regional water-energy-food nexus (WEFN) system was studied in order to promote the sustainable utilization of regional water, energy, and food.[Methods] Based on the theory of complex adaptive systems, an evaluation index system of regional WEFN collaborative development was constructed from three aspects of water, energy, and food. A comprehensive collaborative development model was proposed based on the conditions of various elements and the interaction mechanism based on a co-evolution algorithm and gray correlation. Taking Heilongjiang Province as an example, the collaborative development degree of WEFN and the development degree and collaborative degree of its subsystems from 2009 to 2018 were calculated to evaluate the collaborative development status.[Results] ① The development degree of each subsystem was medium, and the gap was small. The collaborative degrees had a large gap, but all showed a fluctuating upward trend. Among them, the collaborative effect of water resources on energy and food, and energy on food was obvious. ② The collaborative development of WEFN was moderate, consistent with the trend of various subsystems, and remained stable after rising fluctuations. The collaborative development of the food subsystem was the highest. ③ Poor collaboration between subsystems was the reason for the low level of WEFN coordinated development. The efficient application of water and energy in agricultural production should be used as a breakthrough to promote the coordinated development of subsystems.[Conclusion] The comprehensive collaborative development model can be effectively used to evaluate the collaborative development status of regional WEFN, and is helpful for regional sustainable development decision-making.

Abstract:[Objective] The effects of ecological engineering construction and afforestation at the initial stage in arid and semi-arid regions was evaluated quantitatively, in order to provide practical guidance for screening out more suitable afforestation treatment technical measures in this region.[Methods] In a Pinus sylvestnis var. mongolica plantation, five treatments were implemented:film mulching and watering (FW), film mulching but no watering (F), watering but no film mulching (W), pruning (P), and check (CK, no watering, no mulching, no pruning). Three evaluation indicators (survival rate, average annual growth, and afforestation cost at the initial stage) were measured, compared, and evaluated by using the membership function value method in fuzzy mathematics.[Results] Survival rate of the five treatments followed the order of FW(96%)>F(95%)>P(92.3%)>W(91.3%)>CK(89.3%). Preservation rate followed the order of FW(94.6%)>F(94%)>W(87.3%)>CK(80%)>P(77%). Average annual growth followed the order of FW(14.6 cm)>F(13.5 cm)>W(11.5 cm)>P(10.6 cm)>CK(9.7 cm). Afforestation cost followed the order of FW (14 037.5 yuan/hm²)>F(11 712.5 yuan/hm²)>W(10 450 yuan/hm²)>P(8 750 yuan/hm²)>CK(8 125 yuan/hm²).[Conclusion] Differences in the initial effect were obvious between the five afforestation treatments according to the comprehensive evaluation, and the overall order was F(0.674 4)>FW(0.666 7)>P(0.508 1)>W(0.425 6)>CK(0.333 3). Therefore, the technology of film mulching and no watering (F) provided the best overall effect and had the greatest potential for promotion and application.

Abstract:[Objective] Flooding is the most fundamental cause of check dam damage. Discussion regarding the analysis and calculation method used for designing check dams to withstand flood damage was conducted in order to provide a useful reference for further development.[Methods] Current calculation methods for designing check dams to withstand flood damage were reviewed, and the applicable characteristics of various methods were compared and analyzed. The applicability of a theoretically strong reasoning formula method for a flood design calculation applicable to check dams was determined. The physical meanings of various parameters were summarized, and then the main points of their application were put forward. A typical example was selected to study and compare the calculation characteristics and applicability of two methods.[Results] The flood survey method was reliable and feasible, but limited by the conditions of flood data. The accuracy and application of the empirical formula had regional limitations. Neither of the methods were suitable for large-scale application. The reasoning formula method had a certain theoretical basis and calculation accuracy, and was simple and practical to implement. For a specific application, attention should be given to the characteristics of check dams located in very small watersheds. For the calculation of the basin eigenvalues L and J, the part of the slope in the furthest flow should be determined. The value of point rainstorm n₁ should be selected from the range of 10 minutes to 60 minutes for the calculation of rainstorm decline index n. μ was too large and m was too small for the runoff generation and confluence parameters, and the corresponding slope values should be selected within a reasonable range.[Conclusion] The reasoning formula method should be the preferred method for the analysis and calculation of flood design characteristics for check dams. Attention must be given to the characteristics of check dams located in very small watersheds in order to grasp the key points in applying the reasoning formula method.

Abstract:[Objective] Soil erosion characteristics and prevention countermeasures in the Yellow River basin were studied in order to provide a scientific reference for comprehensive control of soil and water loss and high-quality development of the ecological environment in the region.[Methods] Soil and water loss data of 2020 were used to determine the area, distribution, and characteristics of soil erosion in the ecological protection and high-quality development planning area of the Yellow River basin. Comprehensive prevention and control measures for soil and water loss in this region were subsequently recommended.[Results] Areas of soil erosion accounted for 33.97% of the total land area. Areas of soil and water loss were mainly concentrated in the sandy region of the middle reaches of the Yellow River, the desert steppe sandy region of Tenggeri-north foot of the Yinshan Mountain, the loess hilly region of the Huangshui-Taohe River basin, and the highland grasslands region in the source area of the Yellow River. Sandy land, dry land (with slope greater than 6°), natural pasture, and other grasslands were the primary locations for soil erosion. Soil erosion presented the characteristics of wide area and large amounts, concentrated distribution, diverse erosion types, and large areas of high erosion intensity.[Conclusion] Soil erosion is still one of the main ecological problems in the ecological protection and high-quality development planning areas of the Yellow River basin. Prevention and control of soil erosion should be combined with the characteristics of regional soil erosion, scientific layout, and various carefully configured measures to promote the green development of soil and water loss control in the planned area.

Abstract:[Objective] The coordination level and spatiotemporal heterogeneity between multifunctional agricultural land use and rural development in China were analyzed in order to promote rural revitalization.[Methods] The multi-functional agricultural land use and rural development index system were reconstructed. The TOPISIS model was used to measure the multi-functional agricultural land use and rural development index in China from 2009 to 2018. Coupling coordination degree model and spatial autocorrelation model were introduced to analyze the coordination level, spatiotemporal evolution characteristics, and agglomeration degree of the two indexes.[Results] ① The multifunctional index of agricultural land use and the level of rural development in China continued to rise over time, and their spatial distribution showed that the distribution characteristics followed the order of "east>middle>northeast>west", and implied a trend of balanced development. ② The coordination level of multi-functional use of agricultural land and rural development in China had improved slightly over time, and all provinces had been optimized from the near-imbalance type to the primary coordination type. Additionally, the distribution characteristics of coupling coordination types were "high in the east and low in the west with Hubei Province as the high value in the central part". The geographical characteristics of primary coordination types in the west changed from a scattered layout to a centralized arrangement, and the optimization trend was significant. ③ Moral's I of coupling coordination among provinces in China had always been positive with a high degree of spatial agglomeration. Jiangxi, Anhui, and He'nan Province in Central China had become the regional polarization center, while the western and northeastern regions were mostly low-low (L-L) type.[Conclusion] The level of coupling and coordination of multi-functional agricultural land use and rural development in China has obvious regional differences. As implementation of rural revitalization accelerates, there has been a trend towards gradual equilibrium. Promoting the comprehensive improvement of rural land, carrying out ecological management and restoration, and optimizing industrial layout are the important means for promoting multi-functional use of agricultural land and high-quality coordinated development of rural areas, as well as shortening of the regional gap.

Abstract:[Objective] The coupling degree and coupling coordination degree of China's rural water resources poverty index and economic poverty index were calculated in order to provide a theoretical basis and policy enlightenment for alleviating rural water poverty and economic poverty.[Methods] Spatio-temporal distribution characteristics and influencing factors of the coupling coordination degree of rural water resource poverty and economic poverty from 31 provinces (cities and districts) in China during 2001-2017 were used with the analytic hierarchy process (AHP), the entropy method, the system coupling coordination degree model, and the spatial Dublin panel data model.[Results] ① On the whole, although the coupling coordination degree of rural water resource poverty and economic poverty in China was not high, it was generally on the rise, and the coupling degree was greater than the coupling coordination degree of 31 provinces (cities and districts) in China. ② From the spatial perspective, the coupling coordination degree of rural water resource poverty and economic poverty in China was spreading from southeast to northeast and southwest. Jiangsu Province and Zhejiang Province in the eastern coastal region, Fujian Province and Guangdong Province in the southern coastal region, and Hu'nan Province in the middle reaches of the Yangtze River had the highest coupling coordination degree. ③ There was a significant negative spillover effect between the coupling coordination degree of rural water resource poverty and rural economic poverty. Fiscal expenditures on agriculture, forestry, and water conservancy play a significant role in promoting the development of agricultural products, while excessively high prices of agricultural products and the proportion of secondary and tertiary industries will inhibit their development.[Conclusion] Countries should increase or maintain financial support to the rural original, give full play to the government and market in the allocation of resources and adjust action. While reasonably adjusting the price of agricultural products, we should increase the input of agricultural technology, strengthen regional division of labor and cooperation, and promote industrial upgrading, so as to ensure the coordinated development of rural water resources and rural economy.

Abstract:[Objective] The evolution process of rural landscape tourism patterns and the response of ecosystem services value were studied in order to provide a scientific basis for the rational planning of rural landscape resources.[Methods] Five remote sensing images of Mashan Peninsula, Taihu Lake National Tourism Resort in Wuxi City, Jiangsu Province from 1984 to 2020 were selected for landscape classification. Land use dynamic degree, transfer matrix, and landscape pattern indexes were calculated. The ecosystem services value (ESV) was evaluated based on the equivalent factor method. The coefficient of sensitivity for each landscape type was calculated. Additionally, correlation analysis and regression analysis between ESV and landscape pattern indexes were carried out using SPSS.[Results] ① From 1984 to 2020, the landscape pattern of Mashan Peninsula changed significantly, and the various types of landscape changed frequently. The area of construction land and shrubs and grass increased over time. In contrast, the area of broad-leaved forest land, bodies of water, bare land, and other land decreased. The landscape patterns tended to be fragmented and complicated, and connectivity weakened over time. ② Mashan Peninsula water system and broad-leaved forest land had the largest proportion of ESV, and contributed the most to regional ESV. ESV declined over time, with a cumulative reduction of 7.08×10⁵ yuan. The value of each individual ecosystem service decreased, and the reduction in value of regulating service was the most significant. ③ ESV was strongly correlated with the landscape pattern index in Mashan Peninsula, but the degree of influence for each index was different.[Conclusion] With the development of tourism, the landscape pattern and ESV of Mashan Peninsula have changed significantly, and the correlation between the two was significant. Ecosystem service benefits can be improved by adjusting key landscape pattern characteristics.

Abstract:[Objective] Spatial-temporal changes of normalized difference vegetation index (NDVI) in the Yellow River basin were analyzed and its response mechanism to climate change and human activities was investigated in order to provide references for appropriate ecological engineering and guarantee ecological protection and high-quality development in the Yellow River basin.[Methods] In conjunction with MODIS NDVI, precipitation, and temperature data, we used unary linear trend analysis, Hurst index, partial correlation analysis, and residual analysis methods to analyze the spatial-temporal changes of NDVI in the Yellow River basin between 2000 and 2018. The NDVI's dual response mechanism to climate and human activities was discussed.[Results] ① NDVI in the Yellow River basin showed increased volatility over time with an overall growth rate of 6.8%/10 year. The NDVI was higher in the southeast and west, and lower in the north and northwest. The NDVI decreased from southeast to northwest. The NDVI was highest in the downstream region, intermediate in the midstream region, and lowest in the upstream region. NDVI also had a V-shaped distribution bounded by the East Asian monsoon eco-geographical area, the northwest arid eco-geographical area (Erdos-Maowusu Sandy Land-Qingyang-Pingliang-Dingxi), the Qinghai-Tibet Plateau eco-geographical area and zone bounded by the northwest arid eco-geographical area, and the East Asian monsoon eco-geographical area (Xining-Gannan-Dingxi); ② The overall trend of the NDVI showed improvement. Its anti-continuity was stronger than continuity with great weak continuity. The improvement area accounted for about 62.32% of the total area, and was distributed as a strip-shaped area in the middle and upper reaches of the Ordos-Mowsu Sandy Land-Qingyang-Pingliang-Dingxi-Xining-Gannan, Taiyuan Basin-Linfen Basin-Guanzhong Plain, and the zone bounded by Yuncheng Basin-Sanmenxia. The degraded areas were dominated by the middle and lower reaches with scattered distribution; ③ The NDVI was positively correlated with precipitation and air temperature, and the intensity of the partial correlation with precipitation was slightly larger than that of air temperature. The NDVI residuals in about 76.7% of the basin were increasing. The overall impact of human activities on NDVI was positive, and was greatest in the midstream region, followed by the upstream region, and finally the downstream region.[Conclusion] NDVI changes in the Yellow River basin are influenced by climate and human activities and exhibit spatial heterogeneity. Appropriate ecological engineering and agricultural production activities play an important role in vegetation restoration.

Abstract:[Objective] The geomorphic characteristics of Laoshan Nature Reserve in Yunnan Province and its impacts on land use were studied in order to provide support for resource and environmental management and biodiversity conservation in this area and in similar nature reserves.[Methods] The study was conducted at the Laoshan Nature Reserve in Southeast Yunnan Province. Field geological and geomorphic survey data were combined with digital topographic analysis using DEM data with 12.5 m resolution. Elevation, relief, slope, aspect, hypsometric index and topographic profile were selected as parameters to characterize the geomorphic features of the area. Quantitative indexes such as topographic potential index and distribution index were selected to discuss the influence of geomorphic features on land use types.[Results] ① There were three mountain elevation types, six slope grades, six basic geomorphic types, and the distribution characteristics of slope direction with north-south difference. These topographic factors were further differentiated on the lithologic basis of carbonate rock and granite; ② Under the comprehensive action of topographic factors, structure, and lithology, the hypsometric integral of each sub-basin in the reserve ranged from 0.279 to 0.763, and the average hypsometric integral was 0.501, indicating that the reserve was in the early stage of geomorphic evolution. At the sub-basin scale, the reserve showed a spatial pattern of diverse coexistence of juvenile, mature, and old geomorphic stages; ③ As elevation, slope, and topographic index gradient increased, and as slope changed from sunny to shady, the land use type dominated by human factors gradually lost its dominant position and was replaced by the land use type dominated by natural processes.[Conclusion] Unique geomorphic spatial patterns and abundant habitat types are not only important supports for biodiversity, but also important reasons for the formation of spatial allocation of land use types.

Abstract:[Objective] The flood risk related to cultural relics on protected sites was evaluated in order to provide a scientific basis for improving flood control measures and disaster reduction ability for heritage sites.[Methods] The study used data from 311 cultural relics protection units in Chengdu City, Sichuan Province to determine the distribution law of flood risk for cultural relics protection units. A PSR-SPA model was constructed, and the spatial distribution characteristics of flood risk were determined by spatial autocorrelation analysis.[Results] The flood risk of cultural relics protection units in Chengdu City was high in the west, low in the east, high in the north, and low in the south. Flood risk was higher in the urban area than in the suburbs, and higher in the plain than in the mountains. The flood risk level was positively related to the heritage level. The national key cultural relics protection units had a high risk of flood disaster. The cultural protection units with above medium risk were mainly ancient buildings, important modern historical sites, and tipical buildings. Most of these units were in the areas associated with the Song, Yuan, Ming, and Qing Dynasties. The areas with high flood risk were Qingyang, Wuhou, Jinjiang cities, and other primarily urban areas. There was a weak positive correlation in the spatial distribution of flood risk in cultural and social protection units, and there was a certain spatial agglomeration.[Conclusion] National cultural relics protection sites are vulnerable to disasters, and their ability to withstand disasters should be improved. Attention should be given to flood risk prevention and control for ancient buildings, important modern buildings, and cultural relics protection units in areas associated with the Song, Yuan, Ming, and Qing Dynasties, and give full attention to the early warning, prevention, and control of disasters. Districts and counties threatened by floods should further strengthen the construction of flood control information.

Abstract:[Objective] In order to provide a scientific basis for capacity construction and risk management of flood hazards, the social vulnerability to flood in He'nan section of the Yellow River basin was studied.[Methods] Seven prefecture-level city and one provincial (administrated) city along the southern reaches of the Yellow River basin were chosen as the basic assessment unit, and 16 indices were identified from two aspects:sensitivity and social response to flood hazards. The weights of indices were determined using coefficients of variation, and the sensitivity, social response level, and social vulnerability index were calculated using the social vulnerability model.[Results] ① According to the level of sensitivity and social response capacity, social vulnerability was classified as one of three types in He'nan section of the Yellow River basin:low sensitivity-low response capacity (Puyang, Sanmenxia, Jiyuan, and Jiaozuo cities); high sensitivity-low response capacity (Kaifeng, Xinxiang cities); high sensitivity-high response capacity (Luoyang, Zhengzhou cities). ② The social vulnerability level for flood disasters in Kaifeng and Puyang City belonged to level Ⅲ, Luoyang and Zhengzhou cities belonged to level Ⅰ, and other cities belonged to level Ⅱ. ③ From the perspective of spatial distribution, the areas of high social vulnerability were mainly distributed in the lower reaches of the He'nan section of the Yellow River. In the areas of the middle and upper reaches, Luoyang and Zhengzhou belonged to the low social vulnerability classification, and other areas belonged to middle social vulnerability classification.[Conclusion] Areas with high social vulnerability to flood hazards were mainly caused by the low social response capacity and insufficient investment in disaster prevention and mitigation capacity construction.

Abstract:[Objective] The spatial agglomeration characteristics of coupling coordination in He'nan Province were explored, and relevant development suggestions were put forward to provide a scientific reference for the sustainable urban development in He'nan Province.[Methods] An urbanization and ecological environment evaluation system and an improved coupling coordination degree model were used to study the level of urbanization and eco-environmental development and coupling coordination in He'nan Province from 2008 to 2018, and to analyze the spatial-temporal pattern of coupling coordination degree for 17 prefecture level cities in He'nan Province.[Results] From 2008 to 2018, the coupling degree values were all above 0.9 and were in the high coupling level. The coupling coordination degree exhibited a fluctuating upward trend. The urbanization level of most cities was lower than the level of ecological environment. The coupling coordination degree of urbanization and ecological environment in each city could be characterized as basically uncoordinated, basic coordination, coordination, or advanced coordination. There was a spatial positive correlation between urbanization and ecological environment coupling coordination, with clustering characteristics of high coupling coordination in the western and central regions and low coupling coordination in the southeast.[Conclusion] The overall urbanization process of He'nan Province is accelerating, and the economic urbanization and ecological environment pressure are having an important impact on the two major systems of urbanization and ecological environment. It will be necessary to strengthen the development of the central city of in Zhengzhou City and to promote the development of other cities in Southeast He'nan Province.

Abstract:[Objective] Coupling development between the natural ecosystem and the social economy system in the mountainous area of the Southern Ningxia Hui Autonomous Region was studied in order to provide a scientific basis for its sustainable development.[Methods] The mountainous area of Southern Ningxia was chosen as the research area, and an index system for the natural ecosystem and the social economy system was constructed using basic ecological and economic indicators for the region. Then the entropy method was used to determine the weight of each index, and this weight was used to calculate the comprehensive development index of the natural ecosystem and the social economy system. The model of coupling degree and the model of coupling harmony was used to analyze the coupling coordination state and the variation trend between the natural ecosystem and the social economy system.[Results] ① During 2000-2017, the level of social and economic development of each county increased gradually, and the comprehensive development index of the natural ecosystem showed a fluctuating downward trend. ② The coupling degree of the study area showed an initial rising trend that subsequently decreased slightly. However, the overall range remained at 0.89-1.00, which was a high level. ③ The coupling coordination degree of the mountainous area of Southern Ningxia belonged to the coordinated development type. From 2015 to 2017, the degree of coordination in Yanchi County decreased, while the degree of coordination in Tongxin County increased slightly, and the degree of coordination of other counties maintained an upward trend.[Conclusion] With the increase in economic level in recent years, the contradiction between ecology and economy has gradually been revealed because the carrying capacity of the ecological environment in the mountainous area of Southern Ningxia has gradually been unable to adapt to the rapid development of the social economy. The model of coupling coordination degree can well reflect the development process of the interactive stress between the ecological environment and the social economy in the mountainous area of Southern Ningxia, thereby providing the basis for correctly understanding the coupling development law for the ecological and economic systems.

Abstract:[Objective] The temporal and spatial evolution and influencing factors of productional-living-ecological functions of Shanxi Province were analyzed in order to provide a basis for territorial and spatial planning.[Methods] Based on land use type data and statistical data of 107 counties in Shanxi Province in 2005, 2010, and 2018, the spatial and temporal differentiation pattern, evolution process, and influencing factors of the productional-living-ecological functions were determined by using a comprehensive index model, dynamic degree, and a spatial measurement model.[Results] ① The spatio-temporal differentiation feature of the productional-living-ecological functions was obvious in Shanxi Province from 2005 to 2018. The production function and living function were similar, showing a pattern of high in the plains and low in the mountains. The distribution of the ecological function was opposite to that of the production function and the living functions, and the spatial pattern was stable. The comprehensive productional-living-ecological functions improved dramatically, leading to a landform featured by higher in the south and middle, lower in the north, east, and west. ② The production and ecological functions changed slowly, showing a trend from 2005 to 2018 that first increased with time and then decreased. The living function was in a stage of rapid improvement, and it had improved significantly. The comprehensive functions of productional-living-ecological continued to improve, but it was in a stage of slow improvement. The coordination of functions of productional-living-ecological was improved, but the degree of functions simplification was higher. ③ The spatial and temporal differentiation of the productional-living-ecological functions was the combined effects of the natural geographic environment, natural resource endowments, and socio-economic factors. The productional-living-ecological functions were subject to natural geographical conditions. Natural resource endowment was the foundation and guarantee of the productional-living-ecological functions. Socio-economic factors were the main driving force of the productional-living-ecological functions.[Conclusion] All counties in Shanxi Province need to promote the respective enhancement and coordination of productional-living-ecological functions under the constraints of natural geographical conditions and economic and social transformation and development. On the basis of clarifying the positioning of their respective main functions, county planners need to adapt measures to local conditions, and develop measures rationally. Relying on their own regional advantages and endowment of resources, they could establish an interest linkage mechanism and promote the overall coordinated and sustainable development of Shanxi Province.

Abstract:[Objective] The cooling effect of city parks on the urban thermal environment in Yinchuan City, Ningxia Hui Autonomous Region was studied in order to provide guidance for policy-making to improve cooling of the urban thermal environment.[Methods] Land surface temperature (LST) was retrieved from Landsat 8 remote sensing data, and 17 city parks in Yinchuan City were selected to determine the influence of spatial characteristics of the parks' patch characteristics and landscape spatial structure on the internal thermal environment of the city. The cooling effect distance of city parks to the surrounding thermal environment was analyzed, and its affecting extent was quantified. Further research on the thermal environment effect of a typical urban park water area landscape was carried out using landscape pattern and the buffer analysis method.[Results] ① The landscape patch characteristics were significantly different, and the impact on the internal temperature of the park was significant. The internal temperature was significantly negatively correlated with area and perimeter, but significantly positively correlated with perimeter area ratio. ② The internal temperature of the park was closely related to landscape composition, patch morphology, and landscape spatial distribution. The cooling effect was negatively correlated with the area of green space, waterbody, landscape shape index, green landscape shape index, impervious surface shape index, and water aggregation index. ③ The cooling effect of the 17 park landscapes on the surrounding thermal environment was significant, with the maximum cooling distance mainly distributed between 200 m and 300 m. The cooling effect was most obvious within 100 m. ④ Water patches could effectively reduce LST around the water area, and had a better cooling effect on the urban heat island effect than linear water.[Conclusion] During the planning and design of city parks, designers should comprehensively weigh the impact of park patches and landscape spatial structure characteristics on their cooling effects, focus on the area of park green spaces and water bodies, and try to appropriately increase the complexity of boundary shapes of parks and water patches in order to better improve the cooling effect of the urban thermal environment.

Abstract:[Objective] The trend and influencing factors of ecological security in the Three Gorges Reservoir area were studied in order to provide a scientific basis for promoting the development of ecological security in this area.[Methods] Based on pressure-status-response (PSR) model, an ecological security index system was established, and the ecological security status during 2015-2019 was evaluated by the entropy method and the analytic hierarchy process. According to data from the Three Gorges Reservoir area during 2015-2019, the dynamic changes of ecological security in this area were revealed by quantitative evaluation, and verification was performed using the grey clustering method.[Results] ① From 2015 to 2019, the correlation degree of ecological security in the reservoir area was greater than 0.7 for factors such as the application amount of pesticides per unit land area, the amount of topsoil loss caused by vegetation reduction, the ecological service index, and the environmental protection investment ratio. ② From 2015 to 2019, the comprehensive evaluation index of ecological security in some areas of the reservoir area showed an upward trend, while the comprehensive evaluation index of some areas decreased slightly. ③ The agglomeration characteristics of the PSR index in the Three Gorges Reservoir area did not change significantly with time. The high-high agglomeration area was mainly concentrated in the main urban area, which was in line with the general law of economic development. The low-low agglomeration areas were mainly concentrated in Yiling, Zigui, and other counties in the marginal areas. The low-high and high-low agglomeration areas were mainly distributed in the counties surrounding the low-low and high-high agglomeration areas.[Conclusion] The ecological security of the Three Gorges Reservoir area was significantly affected by some indicators. Ecological security construction of the Three Gorges Reservoir area should be promoted based on the important impact factors, and there are great differences between the districts and counties in the Three Gorges Reservoir area. Giving full attention and consideration to the leading role of some districts and counties is the key to the construction of an ecological security system in the Three Gorges Reservoir area.

Abstract:[Objective] The water resource carrying capacity in Hu'nan Province was evaluated in order to provide a theoretical reference for the regional formulation of coordinated development policies of water resources, socio-economic development, and ecological environment.[Methods] The spatio-temporal evolution process of the coupling coordination development of water resources, social economies, and ecological environmental systems in Hu'nan Province from 2009 to 2018 was analyzed by constructing a coupling coordination development model and a comprehensive evaluation index system.[Results] ① The water resource carrying capacity of all cities in Hu'nan Province (except Xiangtan City) from 2009 to 2018 showed an upward trend, and at the same time, showed a U-shaped in space. ② Coupling coordination development showed a fluctuating growth trend as state changed from primary to intermediate. ③ Coupling coordination development from the spatial dimension showed regional differences, from high to low appearing in the west area, east area, and central area. However, the overall imbalance gradually turned to overall coordinated development, with Zhangjiajie City being the best, Changde City being the fastest growing, and Xiangtan, Hengyang and Shaoyang cities being at a low level.[Conclusion] The coordinated development trend of water resource carrying capacity and coupling in Hu'nan Province were in a good condition, but there were significant differences in time and space. In order to improve the carrying capacity of water resources and achieve high-quality sustainable development, the policy support, aiming to improve the carrying capacity of water resources and achieve high-quality sustainable development, could be issued by Hu'nan Province. Which will be respectively enhanced from the perspectives of industrial structure optimization, investment in water conservation and pollution discharge science and technology, the transformation of resource advantages, and green ecological agriculture development.

Abstract:[Objective] Issues related to rural eco-environmental quality assessment in the Jinghe River basin of Gansu Province were studied in order to provide references for rural eco-environmental protection and high-quality development research.[Methods] Based on the pressure-state-response (PSR) model, a rural eco-environmental quality evaluation index system for the Jinghe River basin in Gansu Province was constructed. The eco-environmental quality level was evaluated using the entropy method and the comprehensive index method. The model was predicted by using gray GM (1,1).[Results] The grade change trend of the comprehensive index of rural eco-environmental quality from 2010 to 2019 was "bad-poor-medium", but the overall trend was increasing. The pressure index exhibited a V-shaped change pattern, and the state index and response index increased year by year, indicating that the implementation of environmental governance policies were effective. The index was expected to reach a good level by 2021.[Conclusion] In the future, it is necessary to increase investment in rural environmental protection funds and policies in order to improve local environmental protection systems and measures, and to enhance public awareness.