Abstract:[Objective] The seasonal dynamics of soil enzyme activities on the rhizosphere of tropical cloud forests in Limushan National Nature Reserve were quantified in order to provide a scientific basis for improving the ecological functions of soil and water conservation in tropical cloud forests from the perspective of soil enzymology. [Methods] The activity of invertase, urease, catalase, and acid phosphatase in rhizosphere and non-rhizosphere soils was measured. Samples were collected using the shaking off method in the dominant tree species (Cyclobalanopsis championii, Castanopsis fabri, Eurya loquaiana) in tropical cloud forests. Relationships between the seasonal dynamics of soil enzyme activities and soil nutrients were also analyzed. [Results] ① The seasonal dynamics of soil enzyme activities in rhizosphere and non-rhizosphere soils of different tree species varied significantly with season, showed a single peak trend, reached a maximum in August of rainy season. The levels of soil enzyme activities in rhizosphere and non-rhizosphere soils of C. championii, and C. fabri were not significantly different, but were significantly higher than for E. loquaiana. ② The level of enzyme activities in rhizosphere soil were significantly higher than in non-rhizosphere soil for different tree species in tropical cloud forests. These results indicated a positive rhizosphere effect that followed the order of acid phosphatase > urease > catalase > invertase. The rhizosphere effects of acid phosphatase, urease, and invertase were not significantly different among different dominant tree species, while the rhizosphere effects of catalase in C. championii, and C. fabri were higher than in E. loquaiana. ③ The level of soil enzyme activities had a significant positive correlation with soil nitrogen(N), phosphorus (P), potassium (K), and had no significant correlation with soil water content and pH value. [Conclusion] Soil enzyme activities in rhizosphere soil and non-rhizosphere soil in different trees in tropical cloud forests exhibited seasonal dynamics, and the rhizosphere effect was significant. Rhizosphere enrichment occurred for dominant tree species. N, P, and K nutrient limitations may be the dominant controlling factors affecting soil enzyme activity and its seasonal variation.

Abstract:[Objective] The soil aggregate stability and soil erodibility in different vegetation types of exposed feldspathic sandstone regions in the Baojiagou watershed were studied in order to provide scientific guidance for vegetation construction and reducing coarse sand into the Yellow River. [Methods] Soil aggregate stability and soil erodibility in different vegetation types were evaluated by using the Le Bissonnais method. [Results] ① Under the conditions of the slow-wetting treatment, soil structure was dominated by 2 mm and larger aggregates. Under the conditions of the pre-wetting disturbance treatment, the proportion of 2 mm and larger aggregates was 14.79%~40.17%. Under the conditions of the fast-wetting treatment, the content of 2 mm and larger aggregates was 4.69%~15.11%. ② The destruction rate of soil aggregates was influenced by vegetation, and followed the order of bare land > grass land > Pinus tabuliformis forest > Prunus armeniaca forest > Caragana korshinskii forest > Hippophae rhamnoides forest. ③ The soil erodibility K value in the exposed soft rock area ranged from 0.045 to 0.092, and the disintegration rate of soil in different vegetation types ranged from 0.48 to 1.38 g/min. [Conclusion] H. rhamnoides and other artificial vegetation can significantly enhance the stability of soil aggregate structure, reduce soil erodibility, improve soil corrosion resistance, and thus effectively reduce erosion and sediment yield processes.

Abstract:[Objective] The effects of slope planting measures on soil moisture, runoff, and sediment yield in the karst area of Central Guizhou Province were assessed in order to provide a scientific basis for the prevention and control of soil and water loss on slopes in this area. [Methods] Based on field observation data from 2014 to 2018 in runoff plots of the Yangjichong soil and water conservation monitoring station in Longli County, Guizhou Province, the effects of rainfall and different planting measures on soil moisture, runoff, and sediment yield on slopes in the karst area of Central Guizhou were studied and analyzed by using correlation analysis and significance test. [Results] ① Soil moisture contents for different planting measures followed the order of bayberry > peach > raspberry > poplar > pear > poplar+Mexican cypress > grassland > Mexican cypress > corn (contour tillage). There was a significant positive correlation between soil moisture content and rainfall. ② The annual runoff and sediment yield on slopes were the largest with the poplar planting treatment in the contour tillage (corn) system in a soil and water conservation forest, and the soil and water conservation effects were the worst; soil and water conservation effect was the best for the fruit forest planting systems, among which peach planting was the best. ③ There was a positive correlation between runoff, sediment yield, and average rainfall intensity and maximum 30-minute rainfall intensity (I₃₀). Except for the poplar+Mexican cypress and bayberry planting systems, there was a significant positive correlation between runoff and sediment yield and rainfall under other seven planting systems (p<0.05). [Conclusion] Compared with sloping farmland, the farming systems using fruit-bearing forests, water conservation forests, and ecological restoration of grassland can increase soil moisture content, decrease runoff and sediment yield in different degrees, enhance soil erosion resistance, and effectively reduce soil erosion risk.

Abstract:[Objective] In order to scientifically evaluate the effect of ecological restoration of rocky desertification land, the dynamic changes and interrelationships of karst rocky desertification land and river sediment content in the Pearl River basin were studied. [Methods] Based on the third rocky desertification monitoring result data which were issued in 2018 and the 2000—2018 “China River Sediment Bulletin” data, mathematical statistics, chart functions, and correlation analysis were used to study dynamic changes in and interrelationships of rocky desertification land and river sediment content. [Results] ① The area of rocky desertification land in the Pearl River basin accounted for 34.1% of the country. Since the beginning of the 21st century, the area of regional rocky desertification land has continually decreased, the degree has been reduced, and the ecological environment has improved significantly. ② From 2001 to 2018, the inter-annual variation of the annual sediment transport at major hydrological stations was not obvious. The annual sediment transport, annual average sediment concentration, and multi-year average sediment transport modulus of rivers generally showed a downward trend. [Conclusion] There is an exponential positive correlation between the rocky desertification land area and river sediment content in the Pearl River basin. The amount of sediment transported by rivers and the area of rocky desertification land are exponentially negatively correlated with the comprehensive vegetation coverage and exponentially positively correlated with the area of arable land.

Abstract:[Objective] The influence of vegetation restoration on soil physical and chemical properties of shallow fissures and soil shear strength in karst-faulted basins in Eastern Yunnan Province was explored in order to provide a scientific reference for the mitigation of soil loss and the effective control of rocky desertification in this area. [Methods] The vertical variation characteristics of soil properties and soil shear resistance in the shrub crannies of a secondary forest of Pinus yunnanensis and Myrsine africanan shrub were analyzed by field sampling, indoor wet screening of soil aggregates and soil shear test. [Results] ① Vegetation restoration could improve the physical and chemical properties of fractured soil, but there were differences with changes in soil depth. Organic matter, sand content, and water stable aggregates (>0.25 mm) in the fissured soil of two different vegetation communities decreased with increasing soil depth, while the clay content and water stable aggregates (<0.25 mm) increased with soil depth. The contents of sand particles (55.46%), organic matter (19.63 g/kg), and water stable aggregates (>0.25 mm, 76.51%) in cracked soil of a secondary forest of P. yunnanensis were more than M. africanan shrub (50.16%, 11.31 g/kg, 67.57%, respectively). The contents of silt (17.55%), clay (26.99%), and small water stable aggregates (23.49%) were more than M. africanan shrub (22.56%, 27.27%, 31.43%). ② The cohesion of fractured soil in both communities increased with the increaseing water stable aggregates (>0.25 mm) (p<0.05), and the friction angle of soil decreased with decreasing aggregates of sand, organic matter, and water stable aggregates (<0.25 mm) (p<0.05). ③ The shear strength of the fissured soil in the two communities decreased with increasing soil depth, and the secondary forest of P. yunnanensis community was better than the shrub community in improving the shear strength of the shallow fissured soil, especially in the middle and deep fissured soil. The shear strength of the secondary forest of P. yunnanensis > M. africanan shrub fissure. The difference in shear strength of the fissured soil in the two communities was very significant (p<0.01). [Conclusion] In the rocky desertification region of the fault basin in Eastern Yunnan Province, the arbor community is more helpful in improving the physical and chemical properties of the middle and deep soil, improving soil shear strength, and alleviating the loss of shallow fissured soil.

Abstract:[Objective] The effects of Pinus armandii plantation canopy of different age on the dynamic characteristics of natural rainfall at Mount Mopan, Central Yunnan Province were explored in order to provide certain theoretical references for regional water and soil resource protection and forest structure adjustment. [Methods] 74 natural rainfall observations were obtained for Mount Mopan in Xinping County, Yuxi City, Yunnan Province from May to October 2019. These data included simultaneously observed rainfall and raindrops inside and outside of a middle-aged forest (15-year-old), a mature forest (40-year-old), and an over-mature forest (60-year-old) of a P. armandii plantation using the filter paper splash procedure. 11 representative rainfall events from among the data were selected, and the three forest stands for different rainfall conditions that impact the energy characteristics of raindrops were analyzed. [Results] ① The P. armandii forest had the effect of collecting and dispersing raindrops, and the middle-aged forest had the strongest effect on raindrop dispersion, followed by mature forest. The over-mature forest had the strongest collecting effect. ② The terminal speed of raindrops inside and outside the forest had a very significant positive correlation with the diameter of raindrops (p<0.01). The terminal speed of raindrops in the forest followed the order of middle-aged forest > mature forest > over-mature forest. ③ Increased raindrop diameter and rainfall intensity enhanced rainfall energy inside and outside the forest, and raindrop energy had a very significant positive correlation with both (p<0.01). Under different rainfall conditions, the rainfall kinetic energy and raindrop diameter can be fitted to a power function relationship. Raindrop energy in the forest followed the order of middle-aged forest < mature forest < over-mature forest. The weakening effect of middle-aged forest on raindrop energy was more obvious. ④ The buffering potential energy of middle-aged forest on raindrops was the best at 66.67%, accounting for 52% of the total rainfall potential, followed by mature forests at 31.58%, and over-mature forests at only 20.64%. [Conclusion] The influence of a forest canopy in reducing raindrop energy weakens as trees age. Therefore, for P. armandii plantations older than mature forests, timely harvesting and regeneration of forests should be carried out, and more attention should be given to the protection of understory litter to reduce soil erosion caused by raindrops under the forest canopy.

Abstract:[Objective] The effects of mechanical sand barriers on surface erodibility in sandy areas which experience windy conditions were clarified in order to provide a theoretical basis for the application of a sand barrier in sand prevention engineering. [Methods] Soil samples taken from biodegradable polylactide (PLA) sandbag barriers, Salix psammophila sand barriers and reed sand barriers laid in different years on the windword slope of the northern margin of Kubuqi Desert were used to analyze soil organic matter content, soil particle size composition and soil erodibility K value at the 0—20 cm depth. [Results] ① The laying of sand barriers increased soil organic matter content. The 2 m×2 m S. psammophila sand barrier had the best effect on the accumulation of soil organic matter, and the soil organic matter content on the windward slope was relatively small. ② Laying of sand barriers increased the content of clay, silt, and fine sand in the barriers, and those contents increased with increased laying time. The soil in 0—20 cm layer was dominated by fine sand. ③ Laying of mechanical sand barriers could reduce soil erodibility, and the soil in the lower barriers of the dunes had the best erosion resistance under various site conditions. Among the three types of mechanical sand barriers, the S. psammophila sand barriers had the highest erosion resistance. Barrier effectiveness increased with laying time, and soil erosion resistance also increased. Four years after installation of sand barriers, the risk of soil erosion within the 2 m×2 m laying specification was relatively small. The soil erodibility K value and the soil organic matter content were negatively (p<0.01) correlated. [Conclusion] The laying of sand barriers increases the content of soil organic matter, and is conducive to the accumulation of fine-grained substances, thereby enhancing soil anti-erodibility. It is an effective wind erosion control measure for controlling mobile sand dunes. It is recommended that when laying mechanical sand barriers on the northern edge of the Kubuqi Desert, a 1 m×1 m PLA sandbag barrier should be laid on the upper part of the windward slope, a 2 m×2 m sallow sand barrier should be laid in the middle part, and a 2 m×2 m PLA sandbag barrier should be laid on the lower part of the windward slope.

Abstract:[Objective] The regulating effects of soil bulk density and straw mulching on soil and water loss on slope cropland in the black soil region of Northeastern China were studied in order to facilitate further improvement and application of conservation tillage practices including no tillage and straw returning to fields. [Methods] Two levels of soil bulk density (1.2 and 1.3 g/cm³, representing the soil with conventional tillage and no-tillage practices, respectively) and four levels of straw mulching (0, 328, 656, and 984 g/m²) were considered in this study. For these treatments, simulated rainfall experiments were conducted. The starting times and rates of runoff generation as well as the amount of soil and water loss for each treatment were measured. [Results] ① Soil and water loss of the treatments with bulk density of 1.3 g/cm³ were significantly higher than observed for the treatments with bulk density of 1.2 g/cm³. Specifically, the starting time of runoff generation was reduced by 13.1%～49.9% by decreasing soil bulk density, and correspondingly the runoff and soil loss were increased by 0.4%～90.4% and 24.6%～302.8%, respectively, by the decreasing of bulk density; ② In comparision to the control (no straw mulching), straw mulching delayed the starting time of runoff generation by 1.2～2.9 times. Straw mulching also reduced runoff amount by 3.1%～38.9% and soil loss amount by 34.0%～97.9%. These decreases in runoff and soil loss were positively correlated (p<0.01, r=0.862) with straw mulching amount. The best performance of straw mulching in conserving soil and water would be obtained using 656 g/m² of straw mulch; ③ The soil and water loss on the black soil slope land was aggravated by increasing soil bulk density, but relieved by increasing straw mulching as a result of the straw returning practice. On average, no-tillage (increasing soil bulk density, 1.3 g/cm³) and straw mulching practices reduced runoff by 10.7% and soil loss by 74.2%. [Conclusion] In the black soil region of Northeastern China, no-tillage should be practiced in conjunction with straw mulching to prevent soil and water loss on slope cropland, and the optimum amount of straw mulching should be greater than 656 g/m².

Abstract:[Objective] The conditions and factors influencing soil water repellency (SWR) of Heilu soil was explored in order to provide a reference for research on the response of local rainfall infiltration behavior to water repellency under the background of climate change. [Methods] The experiment was conducted on farmland from Changwu County on the Loess Plateau. Measurements were made on soil samples from the 0—20 cm soil layer of a maize field and an alfalfa field. Soil samples from the two crop fields were brought to a laboratory and tested at four soil moisture contents, three bulk densities, and three levels of added octadecylamine (OCT). Water repellency tests were conducted by measuring drip penetration time. [Results] SWR increased with increasing soil moisture content (ranging from 0% to 6%), bulk density, and OCT addition. Soil moisture content, OCT addition, and soil bulk density exhibited multi-factor interaction effects on SWR. Stepwise regression analysis determined that the best model occurred with OCT and water content as regression parameters. Under a soil bulk density of 1.3 g/cm³ at 0% moisture content with 0.15% OCT addition, 2% moisture content and 0.10% OCT addition, the non-water-repellent Heilu soil would turn into slightly water-repellent soil. [Conclusion] More attention should be given to the impact of soil water content and accumulation of polar substances on water repellency risk under different land uses during the process of precipitation infiltration for a Heilu soil under low-water conditions.

Abstract:[Objective] The improvement degree of soil permeability in the artificial pure forest and mixed forest with different tree species conposition during the growth process was investigated, in order to provide a scientific basis for the selection of tree species during forest construction and during the tending and management of existing tree stands in this area. [Methods] Soil infiltration characteristics based on the double ring infiltration method, including initial infiltration, stable infiltration, average infiltration, and accumulative water quantity, were studied under five different forest types that included Platycladus orientalis, Populus alba var pyramidalis, Robinia pseudoacacia, P. orientalis+R. pseudoacacia, and P. alba var pyramidalis+R. pseudoacacia in the southern and northern mountains of Lanzhou City, Gansu Province. [Results] Soil infiltration characteristics decreased with increasing soil depth in the 0—80 cm soil layer. Soil infiltration characteristics under different forest types followed the order of P. alba var pyramidalis+R. pseudoacacia > P. orientalis+R. pseudoacacia > R. pseudoacacia > P. orientalis > P. alba var pyramidalis, indicating that infiltration characteristics of mixed forests were better than those of pure forests. A common empirical infiltration model provided the best estimates of infiltration processes for the five forest types, followed by the Horton, the Philip, and the Kostiakov models. Soil infiltration characteristics had extremely significant positive correlations with soil water content, total porosity, soil organic matter, soil total nitrogen, and mineral nitrogen. Additionally, soil infiltration characteristics had significant positive correlations with capillary porosity, and noncapillary porosity, and had significant negative correlations with soil bulk density. [Conclusion] These research results would be useful for providing a theoretical basis for the selection of tree species in the construction of artificial forests in the northern and southern mountains of Lanzhou City.

Abstract:[Objective] The remediation effects of biochar on eroded mollisols aggregates, define the influence mechanism of biochar on eroded mollisols aggregates were determined in order to provide a scientific basis for remediation of eroded mollisols. [Methods] Four experimental treatments were imposed to determine the effects of biochar on aggregates of an eroded mollisols: uneroded farmland as the control treatment (CK); uneroded farmland with biochar application (CK+BC); simulated eroded soil (RS); and biochar added to eroded soil (RS+BC). [Results] Biochar application increased the content of 0.25～2 mm size aggregates by 14.01% in CK+BC compared with CK. The content of 0.25～2 mm size aggregates in RS+BC treatment increased by 12.11% compared with RS. In addition, biochar increased the geometric mean diameter (GMD) and the contents of macro-aggregates (R_0.25), and the concentration of soil organic carbon (SOC) in bulk soil and aggregates larger than 0.25 mm. These results indicated that biochar improved the SOC content by increasing its macro-aggregates. GMD was positively and negatively correlated with the concentrations of SOC and exchangeable sodium, respectively. However, the function of SOC in aggregation was larger than function of exchangeable sodium in dispersion, resulting in improved aggregate stability. [Conclusion] Biochar improves the structure of eroded mollisols, promotes soil aggregation, and has a good remediation effect on the eroded soil, and is therefore an effective strategy to remediate eroded soil.

Abstract:[Objective] The niche characteristics of understory herbaceous plants in Pinus tabuliformis plantation forests in the feldspathic sandstone area were explored in order to provide basic data for local Pinus tabuliformis plantations to maintain biodiversity and community stability. [Methods] The types, quantity, average plant height, and coverage of various herbaceous plants were recorded by field investigation in a well-growing P. tabulaeformis forest area. Based on the survey data, the Shannon and Levins niche breadth index, Levins niche overlap index, and ecological response were used to analyze the niche characteristics of understory herbaceous plants. [Results] ① There were 35 species of herbaceous plants in the P. tabulaeformis plantation forest in the arsenic area. Among them, Stipa bungeiensis had the largest niche breadth indexes with better performance. Because of this species’s strong adaptability, its community was in an obviously advantageous position. ② The overall niche width and niche overlap index were generally not high, and understory herbaceous species were differentiated. ③ 37.15% of understory herbaceous species were developing species, and 62.86% of species were declining species. Among the 14 dominant species, 11 were developing species. The developing species with the largest resource occupancies were S. bungeana (0.188 5), Heteropappus altaicus (0.053 1), and Cleistogenes squarrosa (0.037 9). [Conclusion] Competition among understory herbaceous plants in P. tabulaeformis plantations in the arsenic area was weak, and the community species had poor utilization of resources and environment. Most of the dominant herbaceous species were in the developing stage, indicating that the P. tabulaeformis plantation community tended to be relatively stable at this stage.

Abstract:[Objective] The differences in soil erodibility between alpine grassland and alpine meadow in the Qinghai-Tibet Plateau were determined, in order to provide important reference for soil erodibility in alpine grassland. [Methods] 18 change factors were selected as potential influencing factors of soil erodibility for grassland and meadow. Principal component analysis, stepwise regression analysis, and path analysis were used to determine the main influencing factors of soil erodibility in order to select the key factors. [Results] The soil erodibility of alpine grassland was mainly affected by soil particle size and aggregate characteristics. Soil erodibility of alpine meadow was mainly affected by particle size and pore distribution, organic matter, aggregate characteristics, and permeability. The key factors of soil erodibility in alpine grassland were as follows: silt, mean weight diameter (MWD), aggregate size > 2 mm processing damage rate (PAD_>2), and aggregate size > 0.25 mm processing damage rate (PAD_>0.25). The key factors of soil erodibility in alpine meadow were as follows: silt, clay, aggregates size > 1 mm processing damage rate (PAD_>1), and soil saturated hydraulic conductivity. [Conclusion] Grassland and meadow soil showed great differences in particle mechanical composition, organic matter content, water content, and so on. The state of meadow soil was more suitable for vegetation development.

Abstract:[Objective] The water-sediment relationship and sediment transport in different glacial rivers and their responses to climate change were analyzed, and the sediment erosion intensity was assessed in order to provide a theoretical basis for the study of water and sediment dynamics of glacial rivers in alpine mountainous areas. [Methods] The Rongbu River and the Keqikar River were selected as the research objects. During the ablation period (from May to October in 2018), field observation and water sample collection of the glacier rivers were conducted. The hydrological model method was used to simulate the runoff of the Rongbu River, considering the effects of temperature and precipitation, combined with the suspended sediment rating curve, the sediment hysteresis loop, and regression model to analyze the suspended sediment transport and influencing factors of the glacial rivers. [Results] Temperature was the main factor affecting the transport of suspended sediment in glacial rivers in an alpine mountainous area. The runoff modulus values during the ablation period of the Rongbu River and the Keqikar River were about 7.36×10⁵, 6.82×10⁵ m³/(km²·a), respectively. The suspended sediment transport modulus was about 200 and 890 t/(km²·a). [Conclusion] The Rongbu Glacier is highly sensitive to climate change and has a strong ablation ability. Sediment mainly comes from the erosion of the bottom and slope of the river channel by melt water and rainfall. However, due to insufficient erodible sediment and hydraulic conditions, the sediment transport modulus of this area is lower than others. The Keqikar River is located in the arid area of Northwestern China, and sediment discharge is mainly determined by the source of sediment. As the temperature rises, a large amount of moraine material is transported downstream, and sediment erosion intensity is significantly higher than observed from most other glaciers.

Abstract:[Objective] The effects of forest canopy type on water quality of rainfall with different pH values were studied in order to provide a basis for studying the effects of acid rainfall on forest ecosystems in the Huoditang forest area of the Qinling Mountains. [Methods] A self-made artificial rainfall device was used to simulate rainfall on three main forest types (Pinus tabuliformis，Pinus armandii, and Quercus aliena var. acuteserrata). Changes in the concentration of rainwater chemicals in the canopy of each forest were analyzed by rainfall time and rainfall acidity. [Results] ① The concentrations of NH₄⁺, NO₃^-, K⁺， Ca²⁺， Mg²⁺, Pb, Zn, and Cd in the throughfall of the three forests canopies reached peak values after 10—20 minutes, and the concentration decreased and stabilized after 20—30 min of rainfall. The concentrations generally increased first, and then decreased and tended to be stable with the extension of rainfall time. ② The different leaf tissue characteristics of the conifer forest and the broadleaved forest affected the leaching amount of chemicals in forest canopies. With the same pH value, the concentrations of NH₄⁺, NO₃^-, K⁺， Ca²⁺， Mg²⁺, Pb, Zn, and Cd in the throughfall were higher in P. tabuleformis and P. armandii than in Q. acuminata. ③ Acid rain can promote the loss of chemicals in forest canopies. For the same tree species, with different pH values of leaching rain, the concentrations of NH₄⁺, K⁺， Ca²⁺， Mg²⁺, Pb, and Cd in canopy throughfall and the variation range of their concentrations generally followed the order of pH_4.0 > pH_5.0 > pH_7.0. [Conclusion] According to the dynamic change process of chemical substance concentration of canopy throughfall with rainfall time, the impact process of canopy on throughfall water quality can be divided into two stages: rainfall washing (rainfall of about 10—20 minutes) and rainfall leaching (rain starts to 10 or 20 minutes later). In the rainfall washing stage, the canopy has a great influence on the water quality.

Abstract:[Objectives] The degree of heavy metal pollution and ecological risks in the soil of vegetable greenhouses in Tianshui City, Gansu Province was evaluated in order to provide a scientific basis for the safe production of agricultural products in that area. [Methods] 362 soil samples were obtained from 21 villages and towns in the main greenhouse vegetable production areas of Tianshui City. We used ICP-MS to determine the contents of As, Ni, Cu, Zn, Cd, Pb, and Hg, and employed the Nemerow comprehensive pollution index and potential ecological risk index to evaluate the environmental quality and potential ecological risks of heavy metals in vegetable greenhouse soil. We used correlation analysis and principal component analysis to explore the sources of soil heavy metals. [Results] ① The average contents of As, Ni, Cu, Zn, Cd, Pb, and Hg did not exceed the soil risk screening value of the “Soil Environmental Quality Control Standard for Soil Pollution Risk of Agricultural Land (Trial)” (GB15618-2018). However, compared with the soil background values in Gansu Province, Cu, Zn, Cd, Pb, and Hg had generally accumulated, and were 1.9, 1.4, 3.1, 1.3, and 5.2 times of the background values, respectively; ② The average value of the Nemero composite pollution index was 0.508, and 9.9% of the points showed light and moderate pollution. The average value of the polymetallic potential ecological risk index was 289, and the contribution rate of Hg to the potential ecological risk index was 61.3%; ③ Three principal components of the seven elements were identified. [Conclusion] More than 90% of heavy metals in vegetable greenhouse soil samples were at a safe level, and the potential ecological risk was mild to moderate, with Hg being the largest potential risk factor. Sites with light and moderate pollution and sites with strong and very strong potential ecological risks were concentrated in cities and towns with intensive farming and along densely populated areas and traffic lines.

Abstract:[Objective] The soil moisture movement in grassland under the background of urbanization was studied in order to provide a scientific basis and technical support for improving the construction level of sponge city. [Methods] The study area was an artificial grassland at the hydraulic and hydro-ecological testing ground, located on the Yangzijin campus of Yangzhou University, Jiangsu Province. Observed rainfall data and soil moisture data were used to analyze infiltration depths under various rainfall events. Soil moisture variation processes at the study area were simulated using the HYDRUS-1D model. [Results] During light rain (<10 mm) and moderate rain (10~25 mm) events, rainfall infiltration depths at the grassland study area were not more than 15 cm and 30 cm, respectively. During heavy rain (25~50 mm) and torrential rain (>50 mm) events, rainfall infiltration depths were always more than 30 cm, and sometimes exceeded 60 cm. Root mean square errors of simulated results against observations ranged from 0.012 cm³/cm³ to 0.034 cm³/cm³. [Conclusion] Rainfall infiltration depths at the grassland area are clearly different under rainfall events with different magnitudes, and infiltration depth can generally increase with increasing rainfall amount. Additionally, the HYDRUS-1D model can accurately simulate rainfall infiltration depths under differing rainfall amounts for urban grassland areas.

Abstract:[Objective] The industrial ecological safety of Anhui Province was evaluated and predicted, in order to provide a scientific basis for the sustainable development of industrial ecological safety in Anhui Province. [Methods] Pressure, state, response framework and ecological, environmental, economic, and social framework were used to establish the industrial ecological safety evaluation index system. Clustering tools were used to classify safety levels, and combined the entropy weight method and the comprehensive index method to evaluate the industrial ecological safety level in Anhui Province from 2009 to 2018. A BP neural network model was employed to scientifically predict the industrial ecological safety level in Anhui Province from 2019 to 2025. [Results] ① From an overall perspective, the industrial ecological safety evaluation index of Anhui Province from 2009 to 2018 showed a fluctuating upward trend, and the safety level rose from “critical safety” to “safer”. ② From the perspective of each subsystem, the evaluation index of the pressure subsystem showed an upward trend from 2009 to 2018, and the evaluation indexes of the state and response subsystems first declined and then increased. ③ The overall situation of industrial ecological state in Anhui Province from 2019 to 2025 fluctuated and rose, and the safety level rose from “critical safety” to “safer”. ④ The main obstacles affecting the industrial ecological safety of Anhui Province included the ratio of employees in the secondary industry, the ratio of the secondary industry to GDP, and the ratio of centralized sewage treatment, forest coverage, and population density, which providing direction for future regulation. [Conclusion] The industrial ecological state in Anhui Province fluctuated noticeably during the study period, but showed an overall upward trend, and the industrial ecological state was significantly improved.

Abstract:[Objective] The topographic factors were effectively and scientifically quantified while accounting for the local and global self-similarity of ground objects, and the multifractal characteristics of slope topographic factors in different geomorphic areas of the Loess Plateau were summarized in order to provide a reference for subsequent research on topographic factors in the Loess Plateau. [Methods] The digital elevation modle (DEM) data from different areas of the Loess Plateau were selected, and the multifractal characteristics of slope data in each study area were tested by using the method of box dimension calculation multifractal spectrum. The multifractal spectrum and multifractal characteristic parameters of slope fractal body were calculated by multifractal calculation of slope factor. [Results] The variation range of the minimum slope singularity index was 1.82—2.90 in the Loess Plateau area and 1.92—2.43 in the mountain area, and the variation range was relatively large. The minimum slope singularity index ranges were 1.94—2.07 and 1.85—2.19 in the loess hilly region and valley plain region, respectively, with relatively small variation range and relatively uniform topography. The maximum value of the multifractal spectrum corresponding to the maximum slope singularity index was 1.63, and the minimum value was 1.57 in the valley plain area. These geomorphic unit with the smallest slope had the largest proportion in the valley plain area and the smallest proportion in the Loess Plateau area. [Conclusion] Differences in multifractal spectrums in different study areas can truly reflect terrain complexity. Compared with the statistical results of traditional quantitative methods, the multifractal feature parameters can objectively reflect the multifractal features of different terrain regions in the Loess Plateau.

Abstract:[Objective] The change characteristics of eco-environmental quality in the Shenfu-Dongsheng mining area during 1995—2020 were analyzed, in order to provide a scientific basis for improving the ecological environment of the region. [Methods] Principle component analysis was used to create the remote sensing ecological index (RSEI) based on dryness index (NDSI), greenness index (NDVI), heat index (LST), and humidity index (WET) obtained from Landsat 5 TM data and Landsat 8 OLI data (1995—2020). RSEI was divided into five grades by reclassification, and the center of gravity migration of RSEI grades Ⅰ—Ⅴ was analyzed according to the center of gravity migration method. The spatial change law of RSEI was analyzed in order to determine the dynamic monitoring and evaluation of eco-environmental quality of the Shenfu-Dongsheng mining area by using RSEI. [Results] ① The ecological environment of the Shenfu-Dongsheng mining area significantly improved from 1995 to 2020, and the area showing an upward trend accounted for 42.22% of the total area of the mining area. The greenness and dryness indicators had a greater impact on the eco-environmental quality of the mining area. ② Grassland and cultivated land were the main land use types of eco-environmental quality in the mining area, and the change in eco-environmental quality was greatly affected by the change of cultivated land and grassland area. ③ The eco-environmental quality of the mining area was based mainly on grades Ⅱ and Ⅲ. The migration ranges of grades Ⅰ, Ⅱ, and Ⅴ were relatively large, and the center of gravity migrated to the southwest and northwest of the mining area. [Conclusion] The eco-environmental quality of the Shenfu-Dongsheng mining area showed an overall upward trend from 1995 to 2020, and this trend was greatly affected by vegetation growth and human activities.

Abstract:[Objective] The influence of different admixtures on the hydrodynamic characteristics of vegetation concrete slope erosion under rainstorm conditions was analyzed to provide a scientific basis for the improvement of vegetation concrete formulations. [Methods] The erosion status of vegetation concrete slopes under four admixed conditions (no additives, polyacrylamide, biochar, palm fiber) with 60° slope and three rainfall intensities (60, 90, 120 mm/h) were analyzed by using outdoor simulated rainfall experiments. The relationship between slope hydrodynamic parameters and soil erosion was analyzed. [Results] The slope Reynolds number was always less than 500, and the slope flow was laminar. The slope Froude number without admixtures was always less than 1 and the slope flow was slow. The slope Froude number with admixtures was always greater than 1 and the slope flow was rapid. The slope surface with external admixture had a larger slope velocity and water flow power, and smaller water flow shear force, runoff depth, and resistance coefficient. The amount of soil erosion on the slope with biochar addition was significantly higher than without biochar addition. The amount of soil erosion on the slope with addition of polyacrylamide and palm fiber was significantly lower than that without addition. [Conclusion] Use of admixtures had a significant effect on the hydrodynamic parameters of a vegetation concrete slope. The amount of soil erosion was very significantly and positively correlated with Reynolds number and water flow power. Adding polyacrylamide and palm fiber can effectively reduce the amount of soil erosion on vegetation concrete slopes, and can be used in the ecological restoration of high and steep slopes.

Abstract:[Objective] The cultivated land use information was accurately extracted in order to provide theoretical support for farmland management and scientific use of cultivated lands. [Methods] Effective area of arable land in the Naoli River basin was determined using grey system theory and associated theoretical assumptions, mathematical models, mutation detection model, and empirical analysis. Data used in the study came from land use change survey data and the net cultivated land coefficient. [Results] Land use area showed significant grey characteristics. If accumulative treatments were applied to the area of the arable map within a certain area, the linear differential fitting equation could be used to predict the effective area of arable land in Naoli River basin. The grey system theory hypothesis could be applied for the accurate extraction of dryland and paddy fields. In 2018, the effective area of dryland and paddy fields was 1.06×10⁶ hm² and 3.87×10⁵ hm² in the Naoli River basin. The effective dryland coefficient and the paddy field coefficient were 97.65% and 98.07%, respectively. At the same time, the spatial distribution of effective arable land showed that more attention should be given to their actual utilization and development status in the downstream area of the outer Qixing River in the Naoli River basin, and in the northern part of Youyi County and the western part of Baoqing County. [Conclusion] Grey system theory was proposed for determining changes in effective area of arable land. Gray system theory was found to be feasible for extracting effective cultivated land and its coefficient.

Abstract:[Objective] The distribution predicting of landslide disasters in the Yangtze River basin were conducted to strengthen hidden danger investigation and risk assessment, and to improve disaster response capabilities. [Methods] Based on 1 211 landslide distribution points and 15 environmental variables, the MaxEnt model was used to predict the distribution of landslide-prone areas in Jiangxi Province. Then the Jackknife test was used to evaluate the importance of 15 environmental variables to the prediction results. Finally, the area and distribution of landslide prone areas with different risk levels and the main environmental variables affecting the occurrence of landslide disasters were determined. [Results] The extremely high, high, and medium landslide-prone areas in Jiangxi Province accounted for 29.6%, 36.5%, and 23% of the total area of the province, respectively. The probability of landslide occurrence gradually increased from the Poyang Lake plain (as the center) to the surrounding areas, and was concentrated in the western and southern mountainous and hilly areas of Jiangxi Province. Altitude, slope, normalized difference vegetation index (NDVI), average annual rainfall, and distance from rivers and roads were the main environmental variables affecting the occurrence and distribution of landslides, and the cumulative contribution rate was more than 83%. [Conclusion] The distribution of landslide-prone areas in Jiangxi Province has obvious spatial differences, mainly associated with areas of high altitude, complex geology, and developed joints and cracks in rock formations. Rainfall is the direct inducing factor for landslide occurrence.

Abstract:[Objective] The conflicts between water supply and demand, overexploitation of groundwater, and ecological water consumption in the Baiyang River basin in Xinjiang Wei Autonomous Region was evaluated, and the water supply areas of the basin were taken as the research objects to optimize the allocation of water resources for the basin in order to provide a reasonable basis for the healthy development of the economy and the allocation of water resources. [Methods] A comprehensive evaluation model of water resources was used to analyze the water resource carrying capacity of the Baiyang River basin, Daban District, and Tuokexun County. Thus, a multi-objective function model providing for the smallest water shortage, the largest economic benefit, and the best fairness was established. A second-generation non-dominated sorting algorithm (NSGA-Ⅱ) was used to solve the problem. Through the optimization of the results, the optimal water distribution plan was obtained. [Results] The comprehensive evaluation index of the Baiyang River basin was 1.0. After the planning year (2030) when the allocation of water resources was optimized, water consumption decreased by 23.7% (compared with the predicted results of the ARIMA model) and 9.9% (compared with the planned water distribution plan), and GDP increased by 10.5% and decreased by 1.4% respectively. The fairness of water distribution in the basin changed from a wide variation to an absolute average. [Conclusion] The water resources of the Baiyang River basin are currently on the verge being overloaded and slightly uncoordinated. Optimal allocation of water resources could produce the efficient use and reasonable allocation of regional water resources.

Abstract:[Objective] The law of landslide deformation was effectively studied in order to produce high-precision predictions of landslide deformation. [Methods] Using the results of landslide deformation monitoring, an optimized empirical model was used to decompose deformation data. The optimized radial basis function neural network and Markov chain were then used to complete the sub-item combination prediction of landslide deformation. Finally, the seasonal Kendall test was used to judge the landslide deformation trend to verify the reliability of the prediction results. [Results] The empirical model effectively decomposed landslide deformation information, and the decomposition effect was further improved through optimization. The decomposition effect of the complementary ensemble empirical model was the best. The average relative error of the prediction results was less than 2%. This high prediction accuracy verified the effectiveness of the prediction model. The deformation trend judgment results were consistent with the prediction results, indicating that the prediction process was reliable, and that landslide deformation was increasing continuously. [Conclusion] Because landslide deformation tends to increase over time and landslide stability tends to develop in an unfavorable direction, landslide disaster prevention and control should be carried out as soon as possible.

Abstract:[Objective] The effects of different soil substrates on the yield and nutritional components of Morchella fruiting bodies were studied in order to provide the practical cultivation techniques of Morchella in the mountainous area of Southern Ningxia Hui Autonomous Region. [Methods] Three soil treatments were used to cultivate Morchella and to determine effects on fruit body yield: ① raw soil and top soil (control group), ② raw soil + sheep manure (ratio 3∶1), and ③ raw soil + shiitake mushroom residue (ratio 3∶1). Agronomic traits and nutrient content were determined. [Results] The mushroom residue treatment group had the highest fruiting density and the highest yield (2 500 kg/hm²). There were significant advantages in stipe diameter, stipe length, cap diameter, and single mushroom weight with this treatment. The water content (18.56 g/100 g) and crude fiber content (35.65 g/100 g) of the fruit body was highest for the mushroom residue treatment. The contents of crude polysaccharides and crude fat were lower for this treatment, and the contents of essential amino acids (3.46%) and of flavored amino acids (2.76%) were highest. [Conclusion] The addition of lentinus edodes chaff to the cultivation of Morchella was beneficial for increasing the yield and nutritional value of Morchella fruiting bodies.

Abstract:[Objective] The model to optimize design of sponge city residential areas was established in order to provide beneficial support for the stormwater system design and construction such sponge city residential areas. [Methods] Based on discussions of outflow runoff coefficient, runoff pollution, and sponge facilities, and taking the minimum annual cost and maximum runoff pollution reduction rate as objective functions, a bilevel coupling optimization model of sponge city residential areas was established by nonlinear programming. Model validity was analyzed and verified by taking sponge city construction areas in a region of Hefei City as a case study. [Results] After optimization, the outflow runoff coefficients in communities A, B, and C were 0.257, 0.268, and 0.303, respectively. The total cost was 1.11×10⁷ yuan, and the annual cost was 9.87×10⁵ yuan. The runoff pollution removal rate was 70.06%, which significantly improved the economic and environmental benefits compared with the original design scheme. [Conclusion] The application of the bilevel coupling optimization model in the design of sponge city residential areas can effectively reduce the annual cost, increase the reduction rate of runoff pollution, and make sponge city design and construction more reasonable.

Abstract:[Objective] The natural resource space of Liuzhou City, which is located in Southern China with typical karst landform and relatively high development level and density of ecological corridors was accurately divided and a control method was proposed in order to provide a scientific reference for research in other karst areas. [Methods] Based on the spatial superposition method, the INVEST model, and the minimum cumulative resistance model, global scale ecological corridors were extracted, the regional ecological security pattern was constructed, and the precise spatial division of natural resources was determined. [Results] ① The ecological source region was dominated by large woodland with an area of 3 531.24 km², and exhibited an overall increasing trend of fields from the central area to the south and to the north; ② The structure of ecological corridors was distributed in a ring shape that was supported by the main corridors and connected by the minor corridors; ③ According to the finished construction of the ecological security pattern and the natural geographical characteristics of Liuzhou City, the natural resources of this city were divided into four controlling areas: areas where development and construction are forbidden, areas where development and construction are restricted, areas where development and construction were permitted, and areas where development and construction were a priority. Differentiated control methods were proposed in accordance with regional ecological environment problems and spatially dominant functions. [Conclusion] The natural resource space control zone was divided on the basis of the ecological security pattern. The development positioning and goals of each control zone were quite different. Differentiated control must be implemented to promote sustainable development of the region.

Abstract:[Objective] The spatial patterns of urban rainwater were explored, and the network structure and temporal and spatial distribution characteristics of surface runoff of Kunming City were analyzed in order to provide a targeted planning basis for sponge city construction. [Methods] The structure and spatial pattern of a surface runoff network in the central urban area of Kunming City were quantitatively analyzed by using an established GIS database combined with the minimum cumulative resistance (MCR) model and spatial autocorrelation analysis. [Results] ① Potential surface runoff in the study area was affected by the influence of the lateral resistance and local resistance, with a total of 1 274 and a cost ratio was 0.83. Network structures were complex, and the confluence process had significant directionality. ② Runoff connectivity threshold of the sub-catchments was 19.16, and when gravity exceeded a threshold value, runoff among sub-catchments was interrupted. ③ Unit density of the runoff path decreased with increasing gravity among sub-catchments. Potential runoff distribution under six different gravity conditions all showed significant aggregation, but decreasing gradually with increasing gravity. The greater the gravity between sub-catchment areas, the more likely it is that confluence was produced. [Conclusion] The combination of the MCR model and spatial autocorrelation analysis can intuitively reflect the confluence network and distribution characteristics of surface runoff in different rainfall stages.

Abstract:[Objective] The characteristics of future land use structure and spatial patterns under different scenarios were studied in order to provide a decision-making reference for the realization of optimal utilization of regional land spatial pattern and protection of ecology and environment. [Methods] Based on the Markov-DLS model and referring to the evaluation results of production-living-ecological functions of different land use, the characteristics of land use structure and spatial patterns under a balanced development scenario, a food security scenario, and an ecological priority scenario in Jiangxi Province in 2030 were analyzed. [Results] ① The accuracy of land use structure predicted by the Markov-DLS model in 2015 was more than 90%, and the accuracy of the spatial layout simulation was 96%. In addition, the kappa coefficient was more than 92%. ② Cultivated land increased only under the food security scenario, with an increase of 0.48%. Construction land showed a growth trend under the three scenarios, and the growth rate was the fastest in the balanced development scenario, reaching 1.15%. Ecological land (such as forest land, grassland, water area, and unused land) showed an overall downward trend in all three scenarios, but the decline was the smallest in the ecological priority scenario (only -0.36%). ③ The spatial patterns of forest land and grassland in the eastern, southern, and western mountainous areas of Jiangxi Province were relatively stable, while construction land showed a trend of development along shorelines of rivers and lakes, especially along the Ganjiang River, the Yangtze River, and the north bank of Poyang Lake. ④ On the whole, under the ecological priority scenario, the ecological space land (forest land, grassland, water area, and unused land) were protected, the area proportion was the largest of all the scenarios, and the relative decline rate was the smallest. [Conclusion] ① The Markov-DLS model has good applicability for predicting and simulating future land use changes at the provincial scale. ② Changes in land use structure in Jiangxi Province in 2030 under the balanced development scenario, the food security scenario, and the ecological priority scenario show obvious differences. ③ The spatial pattern of the land under the three development scenarios for Jiangxi Province in 2030 shows obvious characteristics of overall consistency and local differences.

Abstract:[Objective] The change in vegetation cover at different time and the spatial variability of vegetation cover change due to different terrain factors such as elevation, slope, and aspect were analyzed in order to provide reference and data support for the restoration and protection of the ecological environment of the national park of Qilian Mountains. [Methods] Based on remote sensing images of the Qilian Mountains in 2006, 2014, and 2019, the pixel dichotomy model was used to estimate vegetation cover, combined with the trend analysis method and the terrain area correction method in order to analyze the spatial distribution and variation characteristics of vegetation cover under different terrain conditions. [Results] ① Vegetation cover was low in the northwest and high in the southeast of Qilian Mountains. Most of the regions were covered with lower vegetation cover. Vegetation cover showed an increasing trend from 2006 to 2019. The increasing areas accounted for about 46.7% of the total area, and the decreasing areas accounted for about 33.3% of the total area. Vegetation recovery was good during this period. The area of low and lower vegetation cover decreased, while the areas of other cover levels increased to varying degrees. ② There were significant differences in vegetation cover at different elevation ranges: The low-middle elevation areas below 3 200 meters showed an increasing trend, and the low elevation areas below 2 200 meters increased significantly, while the middle-high elevation areas above 3 700 meters showed a decreasing trend. The decreasing trend was more obvious at higher altitudes. ③ As slope increased, the trend in vegetation cover change shifted from increasing to stable, and then turned to decreasing in the steep slopes. The vegetation cover change showed an increasing trend in the areas below 15° and a decreasing trend in the areas above 25°, and the decreasing trend was particularly obvious above 40°. For areas with slopes ranging between 15° and 25°, the distribution of types of vegetation cover change was relatively stable. ④ For the different slope aspects, there were no obvious distribution differences for different vegetation cover change types except in the flat land area. [Conclusion] The effects of elevation and slope factors on vegetation cover change were obvious. However, the effect of aspect factor was not obvious.

Abstract:[Objective] The degree of uncoordinated coupling between high-quality development and ecological protection was measured scientifically in order to promote the high-quality development and ecological protection of the Yangtze River Economic Belt. [Methods] A comprehensive evaluation index system was constructed for high-quality development and ecological protection for 108 cities in the Yangtze River Economic Belt. We used uncoordinated coupling, spatial autocorrelation, and other methods to explore the uncoordinated coupling relationship between high-quality development and ecological protection in the Yangtze River Economic Belt from 2005 to 2018. [Results] ① As time progressed, the gap in ecological protection between cities decreased, but the gap in high-quality development increased, and the degree of uncoordinated coupling between the two systems showed a fluctuating downward trend. ② Cities with a degree of uncoordinated coupling less than or equal to 0.5 were mainly concentrated in the downstream region and gradually spread to the middle and upper reaches of the Yangtze River. ③ The degree of uncoordinated coupling between high-quality development and ecological protection in the Yangtze River Economic Belt showed positive spatial autocorrelation, and the spatial agglomeration effect was significant. [Conclusion] There was a large difference in the degree of uncoordinated coupling between the high-quality development and ecological protection of cities. The key to breaking uncoordinated coupling based on ecological protection is to give full attention to the leading role of urban agglomerations and provincial capital cities.

Abstract:[Objective] The coupling and coordination between high-quality development and sustainable land resource utilization in Guangxi Zhuang Autonomous Region was explored in order to provide new ideas and case study references for regional coordinated development. [Methods] The spatial and temporal patterns of coordinated development between high-quality development and sustainable land resource utilization from 2009 to 2018 in Guanxi were quantitatively analyzed by using the entropy weight TOPSIS method, the coupling and coupling coordination degree model, and the spatial autocorrelation analysis method. [Results] ① The high quality development level of Guangxi maintained an upward trend. The sustainable utilization level of land resources fluctuated twice. The type of coordinated development roughly experienced four levels: reluctant coordination, primary coordination, intermediate coordination, and good coordination. ② The high quality development speed and the land resources sustainable use development rise rates were different in each city. The coordination degree of urban development gradually increased from west to east (inland to coastal). ③ During the study period, coordinated development among the 14 cities in Guangxi was not strongly influenced by region, and no city was greatly affected by the neighboring cities. [Conclusion] Over time, high quality development and sustainable land resource utilization level in Guangxi were improved, and the coupling coordination degree was not changed significantly. Across the region, the development speed of each city was not the same. The degree of spatial agglomeration or dispersion of coupling coordination degree was not obvious.

Abstract:[Objective] The most suitable granularity and scale for landscape analysis of the Yellow River Delta were determined, and spatiotemporal changes in landscape pattern vulnerability was analyzed in order to provide a theoretical basis for the sustainable use of land resources and environmental construction. [Methods] The landscape pattern index method and the coefficient of variation method were applied to Landsat remote sensing images from 2005, 2012, and 2018 to determine the most suitable spatial analysis granularity of the study area from the perspective of landscape level and type level. The grid method and geostatistical method were used to determine the most suitable spatial analysis scale. On this basis, the vulnerability indexes of the landscape pattern of the Yellow River Delta in the three study years were separately calculated, and the characteristics of their temporal and spatial evolution and spatial correlation characteristics were analyzed. [Results] ① During the two study periods (2005—2012, 2012—2018) construction land area in the Yellow River Delta increased by 10.1% and 10.0%, respectively, and unused land area changed by -7.7% and -9.4%; ② The most suitable granularity for the landscape analysis in the Yellow River Delta was 220 m, and the most suitable analysis scale was 3 km×3 km; ③ The vulnerability of landscape pattern gradually increased from the coastal area to the inland area. High-vulnerability areas were mainly located in the northern and eastern coastal areas, and the low-vulnerability areas were widely distributed across the central and southwestern regions; ④ Moran’s I coefficient increased over time, being 0.354, 0.365, and 0.399, in 2005, 2012, and 2018, respectively, indicating an increasingly obvious spatial aggregation of landscape pattern vulnerability. [Conclusion] During the study period, the vulnerability of the landscape pattern in the Yellow River Delta gradually deteriorated, and the spatial differences became more significant.

Abstract:[Objective] The spatial distribution patterns of cultivated land and the driving mechanisms of its evolution were studied in order to provide a reference for strictly observing the red line of cultivated land protection, and to formulate farmland resource protection policies and measures in order to optimize the pattern of farmland protection in the Ningxia Eco-economic Belt along the Yellow River. [Methods] Land change survey data and socio-economic data, in conjunction with methods such as nuclear density, spatial autocorrelation, land use dynamics, transfer matrix, and binary Logistic regression modeling were used to analyze the spatial distribution, spatio-temporal evolution, and driving mechanism of cultivated land in the study area from 2010 to 2018. [Results] ① The spatial distribution of cultivated land in the study area showed obvious differences. The overall distribution was mainly in the middle and low density areas, and the distribution evolved from low and high density areas to medium density areas. ② The spatial distribution of arable land was positive. The high-high clustering areas were mainly concentrated in the Yinchuan Plain, and the low-low clustering areas were located in the eastern part of Lingwu City, the central and western parts of Shapotou, and other ecologically fragile areas. ③ The two-way transfer of cultivated land in the study area was an ecological conversion system dominated by unused land-cultivated land-construction land. The amount of cultivated land had been steadily increasing. ④ Cultivated land dynamic changes had obvious spatial clustering that was proportional to the distance from the city and inversely proportional to the city size. ⑤ Natural condition factors were the main driving factors for increases in cultivated land, and socioeconomic factors were the main driving factors for decreases in cultivated land. [Conclusion] The protection of cultivated land in the Ningxia Eco-economic Belt along the Yellow River has basically achieved a dynamic balance. Cultivated land change is based on certain natural condition factors, and is a process of benefit selection under the comprehensive effects of economic, population, and other socio-economic factors.

Abstract:[Objective] The cultivated land changes in the Hehuang Valley were studied in order to provide a basis for the study of the current situation of land use, agricultural development planning, sustainable utilization of cultivated land, and ecological environmental protection in the Hehuang Valley, and to provide references for the study of global cultivated land changes. [Methods] Remote sensing image processing, spatial statistics, and ArcGIS spatial analysis were used to analyze the pattern of cultivated land in the Hehuang Valley from multiple angles. The spatial-temporal evolution law of cultivated land in the Hehuang Valley from 1990 to 2018 was obtained. The relationship between the spatial change of cultivated land and special factors such as altitude and slope were analyzed. [Results] There was a significant change in the pattern of cultivated land in the Hehuang Valley from 1990 to 2018, and the cultivated land area increased. The growth rate of cultivated land was relatively stable from 1990 to 2000. After 2000, the rate of cultivated land reclamation accelerated, and more sloping cultivated land was developed towards the high slope area. After 2010, the cultivated land continued to develop towards the high altitude areas, and the increased rate of sloping farmland cultivation had a tendency to slow down. [Conclusion] From 1990 to 2018, the newly added cultivated land in the Hehuang Valley was reclaimed towards the high-altitude and high-slope areas, and the center of cultivated land shifted to the northwest.

Abstract:[Objective] The relationship between the spatial-temporal variation characteristics of vegetation coverage and topography in Anhui Province was explored in order to provide a theoretical basis for local resource development and ecological environment construction. [Methods] With the support of GIS and RS technology, MODIS / NDVI data of Anhui Province from 2001 to 2019, land classification data from 2001 to 2019, and DEM elevation and aspect topographic data of Anhui Province were used to analyze the spatio-temporal variation characteristics of vegetation coverage and its relationship with topographic factors. [Results] The seasonal variation characteristics of vegetation coverage in Anhui Province were obvious. In January and October to December, the vegetation coverage of Anhui Province was low, and the mountain area was higher than the plain; from February to May, vegetation coverage of Huaibei Plain was high, and decreased rapidly in June; from July to September, the vegetation coverage of Anhui Province was high, with most of the areas greater than 0.8, and the smallest spatial differences observed in the mountain and plain areas. The annual change rate of vegetation coverage was 0.003 9/a, and this change rate was significantly correlated with time (R²=0.814 8). Differences in vegetation coverage in the four seasons were obvious at different altitudes. Vegetation coverage below 200 m was affected by underlying surface types and showed low values. Vegetation coverage increased sharply between 200 m and 350 m, and presented a downward trend above 1 250 m. Vegetation coverage during the four seasons followed the order of summer > autumn > spring > winter. The north and south slopes presented the maximum and minimum values, respectively. Differences of vegetation coverage in the south and north mountain areas showed a downward trend over time. The annual average vegetation coverage differences of south and north mountains were lowest in summer (0.009 3) and highest in autumn (0.014 2), while values in spring and winter were 0.013 9 and 0.012 5, respectively. [Conclusion] Altitude and aspect affected the dynamic variation characteristics of vegetation coverage significantly in Anhui Province. Considering these terrain characteristics is necessary for reasonable development and utilization of land surface resources, as well as for protecting the ecological environment.

Abstract:[Objective] The ecological carrying capacity of water resources in Beijing City was evaluated in order to provide a scientific basis for sustainable development of the region. [Methods] Based on the theory of ecological footprint, the model of ecological carrying capacity of water resources and data from 2010 to 2019 in Beijing City, ecological footprint, ecological carrying capacity, and load index of water resources were analyzed. [Results] From 2010 to 2019, the general trend of the ecological footprint for water resources in Beijing City was very stable, and values ranged from 0.28 hm²/person to 0.32 hm²/person. The per capita ecological carrying capacity of water resources ranged from 0.04 hm²/person to 0.12 hm²/person and was greatly affected by precipitation. The influence of precipitation on ecological carrying capacity of water resources decreased with the input of external water from the south to north water transfer project. The tendency of the ecological footprint of ten thousand-yuan GDP fluctuated up and down, and was consistent with precipitation. Water resources showed a significant deficit, and the load index of water was much higher than 10, with the ecological pressure of water resources being great. [Conclusion] The government of Beijing City has taken active measures to increase the efficient use of water resources in recent years, and some positive results have been achieved. However, the situation regarding water resources in Beijing City is still grim. Although water transfer from south to north has alleviated the serious water shortage in Beijing City to a large extent, the results for ecological carrying capacity have been limited due to the serious consumption of water resources stock capital. Reasonable adjustments to the industrial structure, and further improved use of water resources may become important measures to promote sustainable development in Beijing City.

Abstract:[Objective] The impacts of the driving force of land ecosystem service value in Nanjing City were analyzed in order to provide important evidence for scientific research on the ecosystem service value, ecological protection and construction, optimization of urban and rural spatial layout, and sustainable development of land. [Methods] The ecosystem service values of various land use types were estimated based on land use data from 1990 to 2018 in Nanjing City, Jiangsu Province. The spatiotemporal dynamics of the ecosystem service values were analyzed, and their responses to changes in land use and landscape pattern were demonstrated. [Results] The area of construction land in Nanjing City changed significantly from 1990 to 2018, and was followed by changes in the area of cultivated land. Construction land area increased by 105.67%, while cultivated land area decreased by 19.93%. However, little change was found for cultivated land, grassland, woodland, and water. Patch density of Nanjing City decreased from 0.589 0 to 0.512 5， indicating that the overall landscape fragmentation index continued to decrease. The total ecosystem service value of Nanjing City showed a falling trend, decreasing by 8.13%, while the most significant change existed for water. [Conclusion] Along with social and economic development of Nanjing City, population have a greater influence on the spatiotemporal change of the ecosystem service value than economic factors. Population has increasingly become the main driving factor affecting the ecosystem service value of Nanjing City.

Abstract:[Objective] The wetland ecosystem service value in Hubei Province was studied in order to provide a reference for decision-making regarding wetland protection and restoration, and for human sustainable development in the Yangtze River basin. [Methods] Based on principles of wetland resources, ecology, and economics, 12 indicators were selected to evaluate the wetland ecosystem service value in Hubei Province in 2019 by using market value, reflection engineering, and travel expense methods. [Results] The total value of wetland ecosystem service in Hubei Province reached 1.89×10¹² Yuan in 2019, accounting for 40% of the provincial GDP in 2019. Among the 12 indicators evaluated, the order of values ranked as follows: climate regulation (58.18% of the total value), flood control (16.49%), fresh water products (6.24%), oxygen release (5.50%), hydropower (4.04%), water supply (3.07%), carbon sequestration (2.68%), recreation (2.41%), shipping (1.16%), water quality purification (0.23%), production of raw materials (0.003%), and scientific research and education (0.001%). [Conclusion] Climate regulation, flood control, and fresh water products were the leading ecosystem service values (accounting for 80% of the total value), essentially reflecting most of the important ecological characteristics of wetland ecosystems in Hubei Province.

Abstract:[Objective] The surface water area changes in various cities of Inner Mongolia Autonomous Region were studied, and the correlation between the changes and natural factors and human activities was analyzed， in order to provide a basis for ecological environmental protection and restoration research and water resource management in Inner Mongolia. [Methods] Firstly, normalized difference water index (NDWI) was determined to extract surface water distribution range. Secondly, the initial threshold was determined from statistics of the spectral indexes of seven surface feature types. Finally, the surface water of Inner Mongolia during 2009—2018 was extracted under the optimal threshold, and the spatial and temporal variation characteristics and influencing factors were analyzed by statistical area. [Results] From 2009 to 2013, the surface water area of Inner Mongolia increased continuously (slope=247 km²/year); from 2013 to 2015, the surface water area decreased sharply (slope=150 km²/year); in 2018, the area rose to the highest point. During the study period, the change law and trend of the surface water area and the natural or human factors affecting the surface water area were different for different league (cities). [Conclusion] The variation of annual precipitation and of river runoff was one of the main reasons for the variation of surface water in some Inner Mongolia League cities, such as Alxa League and BayanNur City. Construction of reservoirs, landfill of rivers and cultivated land were the main causes of surface water changes in some cities, such as Wuhai City, Hohhot City, and Xilingol League.

Abstract:[Objective] The coupling and coordination status of various elements of the life community of regional mountains, water, forests, fields, and lakes were analyzed in order to carry out more accurate land space planning, ecological restoration, and comprehensive monitoring of natural resources. [Methods] An evaluation framework was constructed based on the indexes of comprehensive evaluation, coordination degree, coupling degree, and correlation index. Based on the PSR model, the evaluation index system was constructed from the five aspects of “mountain, water, forest, field, and lake”. The comprehensive evaluation model, the coupled coordination model, and the grey correlation model were used to explore the spatio-temporal differentiation characteristics and driving factors of the coupled coordination of the life communities in mountains, water, forests, fields, and lakes in Guangxi Zhuang Autonomous Region from 2005 to 2017. [Results] ① The comprehensive evaluation index of the life community of mountains, water, fields, and lakes rose from 0.918 in 2005 to 0.931 in 2017. Specific performance followed the order of water system > field system > forest system > lake system > mountain system. ② The coupling coordination degree of mountain, water, forest, field, and lake life communities decreased from 0.909 in 2005 to 0.861 in 2017. Although the coupling coordination status was considered good, it had experienced a downward trend. The highest combination coordination between two elements occurred for “water-field”. The highest combination coordination among three elements occurred for “water-forest-field”. The highest combination coordination among four elements occurred for “water-forest-field-lake”. ③ The main driving factor affecting the coupled and coordinated development of the life community in mountains, water, fields, and lakes was water, and the gray correlation degree was 0.723. The specific index factor was soil erosion control. [Conclusion] The life community of mountains, water, forest, field, and lake is an open conceptual category of “mountains, water, forest, field, and lake+”. According to the typical nature of each element, a coupling superposition recombination can be carried out, among which the water element is central to the coupling correlation of each element of the life community of mountains, water, forests, fields, and lakes, and soil erosion control is the key factor. Although the comprehensive level of the life community of mountains, water, forests, fields, and lakes in Guangxi has been improved, the coupling coordination is not likely to be good. Soil and water loss control should be taken as the starting point, and all elements of mountains, water, forests, fields, and lakes should be connected to carry out overall planning and ecological renovation. Integrated monitoring and a quality management system of natural resources needs to be developed in order to improve the state of coupling coordination and to realize sustainable, high quality development.

Abstract:[Objective] The spatial and temporal characteristics of human disturbance in the Guangdong-Hongkong-Macao Greater Bay Area (GHMGBA) was determined in order to provide reference data for solving a series of human-land relationship problems and sustainable development caused by rapid regional economic development. [Methods] The temporal and spatial characteristics of hemeroby from 1980 to 2018 were analyzed, and the spatial heterogeneity of hemeroby from natural and social driving factors was analyzed by using GeoDetector. [Results] ① Land use in the GHMGBA was classified mainly as forest land and cultivated land, but urban land and other construction land had increased by 4.25 times in the past 40 years. ② During the past 40 years, the GHMGBA was dominated by moderate hemeroby, but had developed towards severe and complete. The total intensity of hemeroby was higher in more developed cities and lower in under developed cities. The stability of hemeroby was generally highly stable, but the unstable area expanded rapidly during 2010—2018. ③ The spatial distribution of the total intensity of hemeroby was mainly affected by night light index, traffic density, annual average temperature, elevation, and slope. The factor interaction was mainly manifested as two-factor enhancement and nonlinear enhancement. The total intensity of hemeroby in core cities in the GHMGBA was mainly driven by socio-economic factors, and the total intensity of hemeroby in peripheral cities was mainly driven by natural environmental factors. [Conclusion] The hemeroby of the GHMGBA is expanding and increasing. Under the constraints of topography and geomorphology, the intensity of human activities drives the degree of hemeroby to expand with the city as the center and the sub-center.

Abstract:[Objective] The spatio-temporal variability for inhomogeneity of intra-annual precipitation distribution was analyzed in order to provide the basis for regional water resource management. [Methods] Based on monthly precipitation data during 1970—2019 at 113 stations in He’nan Province, spatio-temporal variability of the precipitation seasonality index (PSI) was evaluated. [Results] ① The spatial distribution of PSI showed that North He’nan Province had higher precipitation inheterogeneity, and more than 28% of precipitation occurred in July; ② He’nan Province could be divided into four sub-regions with different temporal variations in PSI (west, central-east, north, and south areas) by using principal component analysis; ③ After 1990, PSI in west, central-east, and South He’nan Province showed a certain upward trend, while PSI in North He’nan Province showed a stronger short-term oscillation; ④ The interdecadal changes of PSI in most areas of He’nan Province were mainly influenced by ENSO; ⑤ The inter-annual fluctuation of winter wheat yield was more sensitive to PSI than the yield of other grain and oil crops. [Conclusion] The spatial-temporal variability of intra-annual precipitation distribution in He’nan Province was strong, and there were significant regional differences in the correlation between intra-annual distribution and large-scale circulation signals.

Abstract:[Objective] The evolution of temporal and spatial patterns of cultivated land quality was explored in order to provide a basis for decision-making by land management departments at all levels to rationally use and protect cultivated land, and to provide a reference for improving the quality of cultivated land and optimizing the spatial layout of land. [Methods] Based on the evaluation results of arable land quality in Taihu County, Anhui Province in 2008 and 2018, research methods such as time series methods and spatial autocorrelation analysis with ArcGIS and GeoDa platforms were used to analyze the variation in temporal and spatial patterns of cultivated land quality in Taihu County over a ten-year period from global autocorrelation and local autocorrelation. Four types of zoning management plans: restricted construction areas, comprehensive improvement areas, moderate improvement areas, and key remediation areas were devised and formulated, as well as management and protection measures that would meet actual conditions for cultivated land. [Results] ① From 2008 to 2018, the total arable land area of Taihu County increased by 6 474.45 hectares; ② The coefficients of global autocorrelation Moran’s I in 2008 and 2018 were 0.419 478 and 0.288 328, respectively, and the Z scores were 8.677 693 and 5.527 830, respectively; ③ The positive correlation types of cultivated land quality in Taihu County mostly appeared in the form of cluster, while the negative correlation types had no obvious concentrated areas. [Conclusion] The area of cultivated land in Taihu County increased by 6 474.45 hectares over the ten-year period. The average annual change rate (P) of cultivated land resources was 1.65%, and the average grade of cultivated land quality increased by 1.68. The spatial distribution showed significant spatial autocorrelation characteristics and space gathering features.

Abstract:[Objective] The potential pollution risks from livestock and poultry manure on farmland soil and the environment were analyzed in order to provide a scientific basis for non-point source pollution control and resource utilization. [Methods] Livestock and poultry breeding data and crop yield from Anhui Province from 2009 to 2018 were quantitatively analyzed in conjunction with regional crop nutrient demand and nutrient supply from livestock and poultry manure. Combined with existing research results, the spatial and temporal evolution characteristics of the land carrying capacity of livestock and poultry were studied. [Results] The quantity of livestock manure increased from 6.19×10⁷ tons in 2009 to 7.09×10⁷ tons in 2015, and then decreased to 5.00×10⁷ tons in 2018. Pig urine emissions were the largest and cattle urine emissions were the smallest. The discharge of livestock and poultry manure and the supply of nitrogen and phosphorus in the entire province were both higher in the north and lower in the south. The proportion of different livestock manure in the nitrogen supply was balanced, but there was a large difference in phosphorus. The risk of livestock and poultry pollution over the entire province was mainly concentrated in Hefei, Huangshan, and Xuancheng cities located in the central and southern areas of Anhui Province. The land carrying capacity index of the entire province decreased in 2018, and there was still a certain accommodation space for livestock and poultry manure. [Conclusion] Due to pollution risks associated with livestock and poultry breeding in some areas in Anhui Province, it is necessary to strengthen fertilizer application planning and structure adjustment in key areas in order to promote sustainable agricultural development.