Abstract:[Objective] The response of vegetation changes to climate change and their relationship with runoff and sediment was studied in order to provide the basis for the environment policy adjustment of the Yellow River basin.[Methods] The global inventory modelling and mapping studies normalized difference vegetation index (NDVI), as well as temperature, precipitation, runoff, and sediment transport data, were used to study the spatial and temporal variation of NDVI in the Yellow River basin. The linear trend method and correlation analysis methods were utilized. The characteristics of the response of the spatial and temporal variation of NDVI in the Yellow River basin to temperature and precipitation, as well as the impact on runoff and sediment transport, were examined.[Results] ① From 1982 to 2015, the NDVI in the Yellow River basin and the upper and middle reaches of the river basin showed a significant linear increase trend. The middle reaches had the maximum growth rate and the maximum increase in area. ② The area of NDVI in the Yellow River basin was significantly positively correlated with annual average air temperature and annual precipitation, accounting for 22.39% and 21.99%, respectively, and concentrated in the central and northern regions. ③The annual runoff in the Yellow River basin and the upper reaches showed an increasing trend, and the sediment transport volume in the upper and middle reaches showed a decreasing trend, from 2000 to 2015. The relationship between water and sediment in the Yellow River basin was the result of a variety of factors.[Conclusion] Under the background of climate change, the vegetation in the Yellow River basin showed an improvement trend during 1982-2015, but it had evident spatial heterogeneity. The relationship between vegetation change and river runoff and sediment transport requires further study.

Abstract:[Objective] The characteristics of nitrogen (N) transformation in degraded alpine meadows and identify the effects of meadow degradation on the gene abundance of soil nitrogen-transforming microorganisms were studied thoroughly, in order to provide a basis for understanding the degradation mechanism and scientific management of alpine meadows.[Methods] A soil survey along a degraded gradient, including undegraded, lightly degraded, moderately degraded, and severely degraded meadows, in the Qinghai-Tibetan alpine region was conducted. The changes in soil physicochemical properties and genes in N transformation (including nifH, amoA-AOA, amoA-AOB, narG, nirK, nirS, and nosZ) were investigated by using real-time quantitative PCR method, and the drivers of these functional genes were clarified.[Results] ① The contents of soil organic carbon (SOC), total N, nitrate N, and ammonium N decreased along the degradation gradient. ② Degradation led to a significant reduction in the abundance of nifH, amoA-AOA, and amoA-AOB genes, whereas it caused an increase in the abundance of narG, nirS, and nirK genes, which was the maximum in the severely degraded meadow soils. ③ The abundance of the nifH, amoA-AOA, and amoA-AOB genes was significantly positively correlated with the contents of SOC, nitrate N, ammonium N, and soil moisture. The abundance of the narG, nirS, and nirK genes was significantly negatively correlated with the contents of SOC, nitrate N, and ammonium N, whereas it was positively correlated with the pH value.[Conclusion] The degradation of the alpine meadows had an important influence on the microorganisms involved in N transformation. The SOC, pH value, and moisture were the significant drivers of the functional genes in soil nitrogen-transforming microorganisms in alpine meadow soils.

Abstract:[Objective] The rainwater collection capacity of the rainfall collection and infiltration irrigation system of the red plum apricot economic forest in the Pengpu Town of Yuanzhou District, Guyuan City, Ningxia Hui Autonomous Region were investigated, in order to clarify the characteristics of rainfall distribution and provide a scientific basis for the quantitative study of rainfall collection and the development of rainwater-harvesting agriculture in the area.[Methods] The local red plum apricot was used as the research object. Based on the measured data of natural rainfall and artificial simulated rainfall, the rainfall collection process for the red plum apricot economic forest was observed and simulated.[Results] From July to September 2019, 19 rainfall data were observed at the red plum apricot base in Pengpu Town, and the number of rainfalls of less than 5 mm accounted for 83.3% of the total natural rainfall. The correlation coefficient between natural rainfall and artificial rainfall was 0.91, the total collection rate was 61.29%, the interception rate of the infiltration irrigation system was 27.12%, and the canopy interception rate was 11.95%.[Conclusion] The small rainfall frequency in the test field was high, the two rainfall methods had a high similarity, and the rainfall collection and infiltration irrigation system had a high collection efficiency. The rainfall collection of the infiltration irrigation system was linearly related to rainfall (R²=0.995 5), and the rainfall collection rate was logarithmically related to rainfall (R²=0.693 9).

Abstract:[Objective] The effects of rock fragment (RF) size and content on the development characteristics of surface shrinkage cracks in calcareous soil were studied to provide a reference basis for exploring the mechanism of soil erosion in karst areas.[Methods] RF size (2~5 and 5~12.5 mm) and RF content (0%, 10%, 20%, 30%, and 40%) were controlled, and digital-image-processing technology was used to study the effect of RFs on surface crack development in calcareous soil.[Results] ① The surface crack rate (SCR) of the calcareous soil without RFs was only 3.03%, whereas the samples with added RFs had a larger SCR. The maximum SCR of sample (5~12.5 mm, 40%) reached 8.66%. ② When RF content increased, the morphology of the crack network became small and dense, and small RFs made the crack network more complex. ③ The SCR of 5~12.5 mm RFs was positively correlated with the RF content, whereas the SCR of 2~5 mm RFs was negatively correlated with the RF content. ④ RFs can become the basis of fracture development, and each RF probably produce fracture around the RF or extend the crack network. Moreover, at the corner of an RF, it was easy to produce cracks extending outward.[Conclusion] The existence of RFs in calcareous soil could lead to the increase of the SCR and weaken the resistance of soil to erosion.

Abstract:[Objective] To provide scientific support for the disaster prevention and reconstruction of debris flow dams, an experimental study on the process of debris flow dam break under different factors was conducted.[Methods] Dam failure tests were carried out under different inflows, dam shapes, clay contents, dam heights, and initial water contents. The breaking process was divided into four stages:slope surface erosion process, scarp erosion process, lateral erosion process, and decline. The failure mechanism of the debris flow dam was analyzed, and the formula for calculating the critical opening condition for the downstream slope sediment was obtained.[Results] There was a nonlinear positive correlation between the outburst discharge and the inflow water flow. The peak discharge of the outburst increased with the slope degree of the backwater slope. The outburst peak discharge increased rapidly with the increase in the height of the dam, and there was a negative correlation between the clay content and the outburst flow. The peak discharge of the outburst flow decreased slowly with the increase in the initial water content of the soil, but the range of variation was not large.[Conclusion] Among the different factors of debris flow dam break, dam height and clay content have the greatest influence, followed by incoming water flow, backwater slope and initial water content have the least influence.

Abstract:[Objective] The spatial and temporal distribution of the rainfall erosivity, represented as R value, in Guizhou Province from 1966 to 2017 was analyzed to provide reference for evaluating the prevention and control of soil erosion due to rainfall. The goal was to formulate soil and water conservation and agricultural production development measures in the study area.[Methods] Based on the daily rainfall data from 33 meteorological stations in Guizhou Province during 1966-2017, Kriging, empirical orthogonal function (EOF), Mann-Kendall examination, and Morlet wavelet analysis were utilized to analyze the R value characteristics in Guizhou Province over 52 years.[Results] ① EOF analysis well-explained the spatial temporal distribution characteristics of rainfall erosivity. The cumulative contribution rate of the first two eigenvectors reached 52%, revealing two typical distribution modes of rainfall erosivity in Guizhou Province:the whole region pattern and the east-west reverse pattern. According to the analysis of the time coefficient corresponding to the feature vector, the erosive force of rainfall in Guizhou Province was mainly manifested in four ways:the erosive force of rainfall was relatively large during the entire year, it was relatively small during the entire year, it was relatively large in the east and and small in the west, and relatively small in the east and large in the west. ② From the perspective of the entire year, the R value in Guizhou Province was mainly affected by the rainfall in flood season, and the R value in all counties and cities in the province accounted for more than 60% of the entire year. ③ The R value had multiple mutations in its interannual variation. The mutation frequency was the maximum during 1971-1981. Through the cycle test, it was observed that the main cycle of the change was 28 years, and the subcycles were 12 years and 6 years.[Conclusion] The spatial distribution of rainfall and rainfall erosivity was similar in Guizhou Province. Rainfall erosion was generally small in the south and large in the north, and small in summer and large in winter. The rainfall erosivity should increase in the next few years.

Abstract:[Objective] Under the patterns of mulched crops, pasture, and abandoned lands, the effects of land use type on the physical and chemical properties of soil in terraced sloping land were studied to provide support for the optimization of agricultural production management in the terraced sloping land of loess areas.[Methods] Regions of terraced sloping land in the loess area of Longxi County were selected as study sites. Soil sampling was performed for five different land use types:a cornfield, an alfalfa field, land abandoned land for two years, land abandoned for four years, and barren grassland. The sampling was undertaken according to the different slope positions (cutting section, middle section, and filling section), and the physical and chemical properties of the 0-40 cm soil layer were analyzed.[Results] Under different types of land use, the soil moisture content and bulk density increased with increased depth of the soil layer, whereby the cornfield soil had the highest moisture content and the lowest bulk density. The mechanical compositions of the soils ranked as:fine sand > clay > powder > coarse sand. The soil moisture content, bulk density, clay fraction, and powder fraction all showed a trend with slope position as:cutting section > middle section > filling section, while the coarse sand fraction, fine sand fraction, organic carbon content, available potassium content, and hydrolysable nitrogen content, all showed a contrasting trend. The average change of the soil pH value was largest in the alfalfa field and smallest in the abandoned land; there was no significant difference in the analysis of variance (p>0.05). The average changes of soil organic carbon, available potassium content, and available phosphorus content were largest in the cornfield, and the soil hydrolysable nitrogen content was ranked as follows:alfalfa field > corn field > land abandoned for two years > barren grassland > land abandoned for four years.[Conclusion] The cornfield of plastic mulch exhibited better promotional effects for the soil moisture content, bulk density, and nutrient content than the other land use types, and the soil in the filling section was more fertile. During farming, the fertilization of the cutting section should be strengthened.

Abstract:[Objective] The differences in hydrological effects of litters in different vegetation ecosystems were investigated to provide support for the optimization of the ecological spatial pattern in Zhangjiakou region.[Methods] Based on field investigation and statistical analysis, the water-holding capacities of litters at the end of the growing season of three ecosystems (forests, farmland, and grassland) in Zhangjiakou region and its relationship to ecosystem biomass were analyzed.[Results] ① The maximum water-holding capacity (30.7 t/hm²), effective storage capacity (22.97 t/hm²), effective interception rate (187.49%), and water absorption rate (5.84 g/h) of forest ecosystem were superior to those of the other two types of ecosystems. ② The hydrological indicators of grassland were better than those of farmland. Its maximum water-holding capacity was higher than that of forests. ③ There was a significant positive correlation between litter biomass and its maximum water-holding capacity and effective storage capacity, whereas the proportion of litter in the total ecosystem biomass decreased with the increase in total biomass.[Conclusion] On condition that the afforestation method is appropriate, forest ecosystems could improve regional water conservation levels. Simultaneously, the water conservation capacity of grassland should not be ignored. The large-scale expansion of cultivated land in the city to grassland would directly affect the water conservation capacity of the region. In addition, the response relationship between the carbon sequestration capacity characterized by biomass and the water conservation capacity reflected by the litter storage had different performances at different scales of the ecosystem. When optimizing the regional ecological spatial pattern, it was necessary to clarify the water conservation capacity of litters in different ecosystem types at a specific scale, as well as its response to other ecological service functions, to achieve balanced development of each ecosystem.

Abstract:[Objective] The relationship between litter decomposition characteristics and soil nutrient characteristics of Abies georgei var. smithii forest in Southeastern Tibet under different habitat conditions, i.e., in forest (IF), outside forest (OF), and beside forest (BF) was studied to provide basic data for further understanding the material circulation process of the alpine forest ecosystem.[Methods] Based on field decomposition bag method and indoor analysis, in situ decomposition experiments were conducted on A. georgei forest litters in Southeast Tibet under three different habitats.[Results] The decomposition rate showed the characteristics of IF > BF > OF, and the variation coefficient of the monthly decomposition rate represented the characteristics of IF (34.83%) < BF(57.35%) < OF (72.09%). According to the simulation results of the Olson exponential decay model, the decomposition times of litters in different habitat conditions (IF, BF, and OF) were 2.11, 2.52, and 2.34 years, respectively, and 95% of decomposition times were 8.96, 10.01, and 10.84 years, respectively. Soil nutrients in the three different habitats were significantly different in space. The soil nutrient factors in the forest habitats with significant correlation with the litter decomposition rate were soil total organic carbon (TOC) content, N content, soil microbial biomass carbon content, soil microbial biomass nitrogen content, and W_C:W_N value. The soil TOC content was maximum correlated with the decomposition rate of litter in the habitats outside and at forest margins, followed by W_C:W_N value.[Conclusion] The difference of habitat conditions had a significant impact on the decomposition rate and nutrient release rate of litters, and different soil nutrient factors played a leading role in the decomposition of litters under different habitat conditions. The litter-soil biogeochemical cycle was closely related to complex interaction and a prominent habitat effect.

Abstract:[Objective] The effects of exogenous application of corn straw biochar on the soil enzyme activity and microbial community structure were studied to provide soil conditioner for ecological restoration of crude-oil-contaminated soil in Longdong area of the Loess Plateau.[Methods] Three treatments, namely corn straw biochar treatment (B), Calendula officinalis treatment (J), and Calendula officinalis plus corn straw biochar treatment (JB) were applied to the low-concentration (5%) and high-concentration (20%) crude-oil-polluted soil. The change of the soil total petroleum hydrocarbon (TPH) removal rate, the soil enzyme activity, and the soil microbial community structure was investigated by the conventional method.[Results] ① The maximum soil TPH removal rates for the low-pollution-concentration group (TPH=5%) were observed in JB₅ treatment (61.95%±1.39%), whereas the JB₂₀ treatment (56.44%±1.89%) demonstrated the maximum soil TPH removal rate, in the high-pollution-concentration (TPH=20%) group (p<0.05). ② Soil dehydrogenase and polyphenol oxidase activity significantly improved after the application of corn straw biochar. ③ When the crude-oil concentration increased from 5% to 20%, the difference in soil microbial community structure between JB₂₀ and B₂₀ treatments was relatively small. ④ Nonmetric multidimensional scaling analysis revealed that the difference in soil microbial community structure between the treatments of J₅, B₅, B₂₀, JB₅, and JB₂₀ and the treatments of CK₅, CK₂₀, and J₂₀ was caused by the changes of soil dehydrogenase activity, soil polyphenol oxidase activity, Chao1 index, and Shannon-Wiener index of the soil microbial community.[Conclusion] Application of corn straw biochar to crude-oil-polluted soil with low and high concentrations significantly improved the soil dehydrogenase and polyphenol oxidase activity, causing changes in the soil microbial community structure. Consequently, the soil TPH removal rate improved. Therefore, corn straw biochar can be used as a soil conditioner for ecological restoration of crude-oil-contaminated soil in Longdong area of the Loess Plateau.

Abstract:[Objective] The windbreak and sand fixation effects of Haloxylon ammodendron forest lands were analyzed to provide insights for local desertification control and reliable basis for ecological construction.[Methods] H. ammodendron woodland in the Mosuowan area on the southern edge of the Gurbantunggut Desert was taken as a study area. According to the distance from the sand source, four typical H. ammodendron sample plots were selected for soil collection, and the particle size distribution characteristics were analyzed.[Results] H. ammodendron forest located at the sand source had good uniformity and sorting of the sand source because of the dust coming from the Gurbantunggut Desert. The soil particle size was mainly affected by vegetation coverage, which increased the fine-particle composition on the sand surface. Under certain vegetation cover, the average grain size of the surface soil decreased with the increase of sand source distance, mainly because vegetation intercepts sand and dust substances, causing a difference in the particle size of the surface soil. The average particle size of the surface soil increased compared with the lower layer, and there was greater variation close to the sand source. However, the difference in kurtosis and skewness of soil particle size was not significant.[Conclusion] The difference in particle size characteristics of the surface soil reflected the influence of wind-sand activity intensity on H. ammodendron forests under different vegetation coverage. Natural vegetation zones and artificial H. ammodendron forests could effectively intercept and fix a large amount of wind erosion substances. However, because the growth condition of natural vegetation was not as good as that of artificial forest, the effect of the interception of wind-blown sand was weaker under vegetation degradation and wind erosion. Therefore, afforestation on the periphery of the natural vegetation zone played a vital role in blocking local wind-blown sand.

Abstract:[Objective] The stability of the Gaojiawan landslide in Qinghai Province was evaluated to provide insights for disaster prevention and control.[Methods] Based on the analysis of the basic characteristics of the landslide, the formation conditions were studied initially. Afterwards, the stability status quo was evaluated by using the transfer coefficient method and the Swedish arc method, and the deformation prediction model was constructed using the long-term and short-term memory neural network to obtain the stability prediction evaluation. Subsequently, comprehensive research on the stability was performed by combining the stability status quo evaluation results.[Results] The Gaojiawan landslide had the basic conditions for the formation of landslides, and it had the characteristics of a multistage giant scale, and hence prevention and control should be comprehensive. Simultaneously, the present scenario of the landslide was stable, but a local secondary landslide might cause loosing stability, and that stability could be further weakened under adverse conditions. In addition, according to the deformation prediction research results, the average relative error was less than 2%. The results showed that the deformation of the Gaojiawan landslide would continue to increase, and there was no sign of convergence.[Conclusion] The stability of the Gaojiawan landslide could further weaken and tend to develop in a disadvantageous direction. Necessary measures should be taken as soon as possible to ensure stability.

Abstract:[Objective] The sap flow dynamics of Sabina vulgaris and the influencing factors was studied in order to provide theoretical support for the protection of sandy land vegetation.[Methods] The dominant species of S. vulgaris on the Ordos Plateau, which was the typical natural sandy land vegetation in Inner Mongolia, was taken as a case. The sap flow dynamic of S. vulgaris was monitored by thermal dissipation probe technology. Its relationships with climatic factors were analyzed by correlation and regression analyses.[Results] The sap flow dynamics of S. vulgaris was a single-peak curve on sunny days, and a double-peak curve during drought; however, it was a single-or double-peak curve on rainy days. The daily maximal value of sap flow of S. vulgaris was 2.30-23.38 g/(cm²·h) on sunny days. There was a 1-4 days time lag in the response of the sap flow of S. vulgaris to rain. The sap flow was significantly positively correlated with photosynthetically active radiation, vapor pressure deficit, air temperature, and wind speed, but it was significantly negatively correlated with relative humidity and precipitation in the growing season.[Conclusion] The sap flow of S. vulgaris on the Ordos Plateau varied with weather. Solar irradiation and water were the main influencing factors for the sap flow of S. vulgaris. S. vulgaris shrub land should be protected to prevent vegetation degradation caused by excessive water consumption.

Abstract:[Objective] The soil aggregate stability of different species of Pinus yunnanensis in the karst mountain area of Eastern Yunnan Province was studied to provide a basis for soil cultivation, quality improvement, and soil-water conservation of karst fragile habitats.[Methods] Based on the field survey and laboratory analysis, five types of vegetation, namely P. yunnanensis pure forest, P. yunnanensis artificial mixed forest, P. yunnanensis natural mixed forest, shrub, and primeval forest, in the karst mountains of Eastern Yunnan Province were studied in terms of their characteristics of water-stable aggregate and organic carbon distribution in aggregate, which revealed the differences in the soil aggregate stability of different species of P. yunnanensis.[Results] ① The mass fraction of particle size <0.25 mm (5.77%~9.39%) of P. yunnanensis pure forest, artificial mixed forest, and natural mixed forest was significantly lower than that of shrub (20.92%) and primeval forest (27.47%) (p<0.05). The mass fraction of particle size >5 mm and 2~5 mm of artificial mixed forest and natural mixed forest was higher than that of pure forest. ② The proportion order of water-stable aggregate >0.25 mm (R_0.25) after wet sieving treatment was P. yunnanensis artificial mixed forest > P. yunnanensis natural mixed forest > P. yunnanensis pure forest > shrub > primeval forest. The mean weight diameter order was P. yunnanensis artificial mixed forest > P. yunnanensis natural mixed forest > primeval forest > shrub > P. yunnanensis pure forest. The geometric mean diameter order was P. yunnanensis artificial mixed forest > P. yunnanensis natural mixed forest > primeval forest > P. yunnanensis pure forest > shrub. The fractal dimension order was primeval forest > shrub > P. yunnanensis pure forest > P. yunnanensis natural mixed forest > P. yunnanensis artificial mixed forest. ③ The contribution rate of large aggregates (>0.25 mm) of P. yunnanensis pure forest, P. yunnanensis artificial mixed forest, and P. yunnanensis natural mixed forest to soil organic carbon was higher than that of small aggregates (<0.25 mm), and the content of organic carbon in soil aggregates with particle sizes of 5, 2~5, and <0.25 mm was significantly lower than that of shrub and primeval forest (p<0.05).[Conclusion] P. yunnanensis artificial mixed forest was observed to have the maximum soil aggregate stability, and its nutrient accumulation and carbon sequestration were lower than those of shrub and primeval forest but higher than those of pure forest. When the P. yunnanensis artificial mixed forest was planted as the main vegetation type for soil and water conservation in this region, it was necessary to avoid human interference for the purpose of improvement of soil nutrients.

Abstract:[Objective] The change of agricultural water consumption in the northwest arid region of China and its influence were analyzed to provide guidance for the future development of the Yutian oasis.[Methods] Using the meteorological data from 1980 through 2018 and the land-use/cover data from 1990 and 2018 in the Yutian County, Xinjiang Wei Autonomous Region, the water consumption characteristics of the Yutian oasis were analyzed.[Results] ① The climate change in the study area showed a clear warming and humidity trend. The land-use/cover change was mainly manifested in the increase of the cultivated land area of the oasis, whereas the water area showed a decreasing trend. ② The runoff of the Keriya River showed a significant upward trend in the Yutian oasis, with an annual average flow that was 6.00×10⁸ m³ higher than before, and the water consumption of agricultural green water also showed an increasing trend. It was 1.78×10⁹ m³ higher than that in 2000.[Conclusion] The increase of temperature resulted in an increase of crop evapotranspiration, and the increase of cultivated land area aggravated the water consumption, causing the total water consumption of Yutian oasis to increase annually.

Abstract:[Objective] The impacts of socioeconomic factors on soil erosion during 1990-2015 in Jiangxi Province were studied to provide a scientific basis for prevention and control of soil erosion according to regional development needs.[Methods] The spatial distribution of regional soil erosion obtained through the localized revised universal soil loss equation model was simulated. Subsequently, a socioeconomic indicator system based on the city unit (including four first-level indicators and 21 second-level indicators) was built. The impacts on soil erosion in 1999, 2000, and 2015 were identified by using the method of grey relational analysis.[Results] The average soil erosion modulus of regional soil erosion decreased. The values were 864, 663, and 281 t/(km²·a) in 1990, 2000, and 2015, respectively. From 1990 to 2015, the grey relational degree of socioeconomic factors and regional soil erosion showed an overall increasing trend, and the order of the indicators was dynamically changing.[Conclusion] From 1990 to 2015, the regional soil erosion in Jiangxi Province showed evident improvement. The impacts of socioeconomic factors on regional soil erosion were strengthened with social development. Rural development had a remarkable effect, especially for slope farmland. The importance of population level increased noticeably, and the impacts of the ecological conservation factors improved gradually.

Abstract:[Objective] The optimal vegetation coverage of the ecological green heart area of Changsha-Zhuzhou-Xiangtan urban agglomeration and the regional soil and water loss status in 2018 were studied to provide a theoretical basis for comprehensive management of regional soil erosion.[Methods] Using GIS and RS technology, based on rainfall, soil, terrain, land use and other data in the Changsha-Zhuzhou-Xiangtan area, the normalized difference vegetation index and USLE were adopted as the preferred models.[Results] The total area of the Changsha-Zhuzhou-Xiangtan green heart area was 52 287 hm², and the overall vegetation condition was above par. The high coverage (75%~100%) area was the largest, constituting more than half of the total area of the green heart area (26 869.79 hm²); the low coverage (30%~40%) area was the smallest, being only 8.61% of the total area (4 501.90 hm²). The total area of erosion (excluding microdegree) in the green heart area was 3 654.24 hm² (which was 6.99% of the total area). The proportion of erosion in Xiangtan City was the highest (8.51%), followed by Changsha City (6.67%) and Zhuzhou City (5.68%). The erosion area of construction land was 963.92, 310.74, and 735.11 hm² in the prohibited development zone, restricted development zone, and the controlled construction zone, respectively.[Conclusion] The coverage space of the ecological green heart area of Changsha-Zhuzhou-Xiangtan urban agglomeration appeared to be low in the west and high in the middle-east part, which might have resulted from man-made factors, urban construction, and industrial distributions. Engineering construction was the main reason for soil and water loss in the green heart area.

Abstract:[Objective] The relationship of the ecological environment and poverty was studied to provide scientific reference for the targeted poverty alleviation and sustainable development in ecologically fragile areas.[Methods] A typical ecologically fragile area, the Tibetan area in Sichuan Province, was taken as the study area. The coupling status of the ecological environment and poverty in the Sichuan Tibetan area was measured and analyzed by using a coupling degree model and coordination degree model from 2008 to 2017.[Results] ① The coupled development of the ecological environment and poverty in the Tibetan area was relatively stable at a low level from 2008 to 2017, and the coupling degree was mostly between 0.072 2 and 0.706 3. The variation trend of the coupling degree increased annually, but there were fluctuations in 2011. ② From 2008 to 2017, the ecological environment index of the Tibetan area showed an increasing trend annually, with a value between 0.009 5 and 1.000 0. The poverty index also showed an increasing trend annually, with a value between 0.006 3 and 0.995 4, but there was a fluctuation in 2011. ③ In addition to the fluctuation in 2011, the coupling coordination degree of the ecological environment and poverty in the Tibetan area increased annually from 2008 to 2017, and the value was between 0.035 9 and 0.839 4. The variation trends of coupling degrees and coordination degrees were similar from 2008 to 2017. ④ From 2008 to 2017, the coupling and coordination degree between the ecological environment and poverty of the Tibetan area had three different stages:low-level coupling development, coupling transition, and high-level coupling coordination of poverty lag.[Conclusion] In the future, ecological protection and poverty alleviation should be regarded as essential in the Tibetan area of Sichuan Province to achieve sustainable development of socio-economic and environment system in this ecologically fragile region.

Abstract:[Objective] The willingness of the public to participate in the land reclamation of abandoned mines was studied to understand the attitude of the public towards the reclamation of abandoned mine land and to explore the path of public participation in the reclamation of such lands.[Methods] From the perspective of individual behavior, 872 survey questionnaires from five main abandoned mining areas in Ganzhou City, Jiangxi Province, were taken as the study area. Four factors related to the willingness of the public to participate in the land reclamation of abandoned mines were investigated:public demand, behavior attitude, subjective norm, and perceptual behavior control.[Results] ① The coefficients of public demand, behavior attitude, subjective norm, and perceived behavior control for public participation in the land reclamation of abandoned mines were 0.86, 0.56, 0.34, and -0.62, respectively. Public demand was the most important factor that affected the willingness of the public to participate in the land reclamation of abandoned mines. ② Public demand, behavior attitude, and subjective regulation had a significant positive effect on the willingness of the public to participate in the land reclamation of abandoned mines, whereas the perceptual behavior control had a negative effect on it. ③ Among the factors influencing the willingness of the public to participate, there were significant correlations between public demand, behavior attitude, and perceptual behavior control. ④ The influence degrees of each measurable variable of public participation on the latent variable of abandoned mine land reclamation were quite different.[Conclusion] Public participation in the reclamation of abandoned mine land should be based on a solution of the public's own needs, the protection of rights, and the maintenance of fairness and justice.

Abstract:[Objective] The ecological environment quality of the Huangshan World Heritage Site was quantitatively evaluated to provide a scientific basis for relevant departments for making development and management decisions.[Methods] Taking the core area and buffer zone of Huangshan World Heritage Site as the study area, greenness, humidity, dryness, and heat index components were extracted based on Landsat satellite images, and the remote-sensing ecological index (RSEI) was constructed by principal component analysis. Geographic information system based spatial analysis and statistical methods were used to quantitatively evaluate the ecological environment quality of the study area.[Results] The value of the RSEI in the study area increased from 0.573 in 1992 to 0.638 in 2017, and the ecological environment quality of protected area showed a significant upward trend. In the three-year data analysis, the RSEI grades of good and medium reached more than 65%, which was dominant, and the overall ecological environment quality in the protected area was good. Among the lands with a poor and poorer RSEI grade, approximately 63.6% was converted into land with a high RSEI grade, and the ecological environment quality in the protected area was significantly improved.[Conclusion] The ecological environment quality of the Huangshan World Heritage Site steadily improved, and the protective measures of relevant departments achieved the initial objectives. It is necessary to further coordinate the balance between development and conservation to achieve sustainable development of Huangshan World Heritage Site.

Abstract:[Objective] The Qingshui River watershed in the upper reaches of the Haihe River is located in a fragile ecological region where climate varies from arid to semiarid. The spatiotemporal variation of land use in this region was studied for local decision making on ecological construction.[Methods] Based on land use data interpreted from Landsat remote-sensing images at four periods during 1990-2018, the land use changes of the Qingshui River watershed were analyzed and predicted by using the logistic-CA-Markov model under an optimal space scale.[Results] ① During the past 30 years, the land use of the Qingshui River mainly consisted of cultivated land, forest land, and grassland, and the total area of these three land use types accounted for more than 96% of the study area. The area of construction land increased, and its change intensity was the maximum. ② The receiver operating characteristic (ROC) value of each land type reached the best level at a scale of 100 m×100 m, which was obtained based on the goodness-of-fit tests for ROC curves. ③ The area of grassland and water area would decrease by 42.44 and 5.43 km², respectively, from 2018 to 2027. The areas of cultivated land, forest land, and construction land would increase by 16.51, 16.89, and 14.67 km², respectively.[Conclusions] ① The scale of 100 m×100 m was the suitable space scale for the prediction simulation on a typical small watershed, such as the Qingshui River watershed. ② The preparations for the 2022 Winter Olympics drastically accelerated the exploitation intensity of construction land, and they were the dominant driver of the land structure change in the Qingshui River watershed.

Abstract:[Objective] The dominant climatic and non-climatic factors of vegetation cover in Shaanxi Province were studied in order to provide a scientific basis for the construction of regional ecological civilization.[Methods] Based on the MODIS normalized difference vegetation index (NDVI) data from 2003 to 2017, the effects of climatic and non-climatic factors on the vegetation coverage were studied using trend analysis and geographic detector in Shaanxi Province.[Results] ① The NDVI in Shaanxi Province generally improved from 2003 to 2017. However, there were differences between vegetation types and ecological areas. ② In terms of climatic factors, the spatial distribution of vegetation coverage was mainly affected by the precipitation in Shaanxi Province, and other climatic factors had different influences on local vegetation cover. ③ The interaction of precipitation and temperature, sunshine, wind speed, and relative humidity had a leading role in the spatial change of vegetation coverage in Shaanxi Province, whereas the sole interaction between temperature and precipitation had significant effect on vegetation coverage. ④ In terms of non-climatic factors, the spatial distribution of vegetation coverage was mainly affected by vegetation type and the topography in Shaanxi Province. ⑤ Vegetation types and landforms were the dominant non-climatic factors affecting the spatial distribution of vegetation coverage in Shaanxi Province. However, the impact of population and gross domestic product on vegetation cover could only be seen through interaction with other factors.[Conclusion] The influence of climatic factors was greater than that of non-climatic factors. The combined effect of climatic and non-climatic factors could completely explain the spatial distribution of vegetation coverage.

Abstract:[Objective] Soil seed banks of different types of artificial forest land were studied in the Jinta desert of Jiuquan City, Gansu Province, to reveal the artificial vegetation distribution rule of soil seed banks, variety characteristics of species diversity, and relationship between the soil seed bank and the vegetation. The goal was to provide a theoretical basis for the restoration and reconstruction of the degraded plantation ecosystem in the Hexi corridor.[Methods] The analytical research was conducted through field vegetation survey, soil seed bank sampling, and soil germination experiment.[Results] ① There were 24 kinds of plants species. The numbers of soil seed banks of the Populus euphratica-Calamagrostis pseudophragmites community, the P. euphratica + Elaeagnus angustifolia-Tamarix chinensis + Hedysarum scoparium + Caragana korshinskii-Phragmites australis + Artemisia ordosica community, the Haloxylon ammodendron-Hexinia polydichotoma community, and the Tamarix chinensis-Karelinia caspia community were 18, 18, 14, and 3 species, respectively. The seed densities were 660.71, 267.85, 29.64, and 19.29 granules/m², respectively. The species and density of annual and perennial herbs were dominant, and the proportion of arbor, shrubs, and subshrubs was low. ② The analysis of species diversity showed that the Margalef richness index of soil seed banks of arboreal forest was larger than that of the shrubs. The variety trends of the Shannon-Wiener diversity index, Simpson diversity index, and Pielou evenness index of soil seed banks were almost the same as P. euphratica + E. angustifolia-T. chinensis + H. scoparium + C. korshinskii-P. australis + A. ordosica community > T. chinensis -K. caspia community > H. ammodendron -H. polydichotoma community > P. euphratica-C. pseudophragmites community. However, the ecological dominance index was in contrast. ③ The similarity in the arbor soil seed banks of arboreal forest and ground vegetation was higher than that of the shrubs.[Conclusion] The species abundance of the soil seed bank was low in artificial forest lands. Majority of them were herbs, the desert had a low restoration capacity, and the artificial arbor forests and shrubs were beneficial for the restoration and reconstruction of the arid desert area.

Abstract:[Objective] The water-holding capacity of litter and soil in Tiantai County, Zhejiang Province were investigate to provide a scientific basis for forest water conservation in the region.[Methods] The undergrowth litters and water-holding capacity of soil of eight forest types (Phyllostachys edulis forest, broad-leaved mixed forest, mixed broadleaf-conifer forest, coniferous mixed forest, Pinus massoniana forest, Cunninghamia lanceolata forest, Pinus thunbergii forest, and Schima superba forest) in Tiantai County were studied through field investigation and indoor soaking method.[Results] The litter volumes of the eight forest types were 8.05~23.84 t/hm². The maximum capacity range was 14.59~35.15 t/hm² (S. superba forest > mixed broadleaf-conifer forest > broad-leaved mixed forest > P. massoniana forest > C. lanceolata forest > P. thunbergii forest > P. edulis forest > coniferous mixed forest). Moreover, the litters had basically similar change laws of the water-holding capacity with soaking time. The water-holding capacity and soaking time showed a logarithmic function relation, whereas the water absorption rate and the soaking time had a power function relation. The soil bulk densities in the different types of forest were 0.83~1.21 g/cm³. The range of water-holding capacity of soil was 200.74~575.70 t/hm² (P. thunbergii forest > mixed broadleaf-conifer forest > S. superba forest > C. lanceolata forest > P. edulis forest > P. massoniana forest > broad-leaved mixed forest > coniferous mixed forest).[Conclusion] The broad-leaved forest and the forest-type litter with broad-leaved tree species, as well as the soil under the forest, had strong water-holding capacity, and the maximum water-holding capacity of soil was that of the P. thunbergii forest.

Abstract:[Objective] The vegetation recovery process of the co-seismic landslide at central area of Wenchuan earthquake was assessed in order to provide the basis for the ecological environment restoration, disaster prevention, and reconstruction after the earthquake in the study area.[Methods] Yingxiu Town of Wenchuan County, Sichuan Province was taken as a study area, and the dynamic changes of vegetation at landslide sites after the earthquake were analyzed based on multi-temporal images with a resolution of 30 m. The spatial distribution characteristics of vegetation recovery in the past nine years were analyzed based on the topographic factors.[Results] The vegetation of the landslides did not recover well from 2008 to 2011 in the study area, and 68% of the sites were below the "poor" level. During this period, the frequencies of rainstorms and debris flow activity remained high. After 2013, a better recovery level was reached overall, and the number of landsides below the poor level decreased to 32%. Then, it had been in a slow recovery process. In 2017, the landslides with a poor level of vegetation recovery were mainly located in the slope range of 30°-50°, the elevation range of 1 500-2 100 m, and a southeast slope aspect.[Conclusion] In the 9 years after the earthquake, the vegetation cover index increased to 0.74, and the average vegetation coverage index value was 0.08 less than that before the earthquake. Based on the statistical model, the vegetation cover index is expected to return to the pre-earthquake level in 2022. However, the population structure of vegetation with herbs and shrubs is different from that before the earthquake.

Abstract:[Objective] The relationship between population and construction land change in Guizhou Province areas was studied in order to promote the optimal allocation of land resources.[Methods] Using the data of urban and rural population and construction land in Guizhou Province from 2000 to 2017, the evolution process of urban and rural human-land relationship was studied using the decoupling model and GIS spatial analysis method.[Results] From 2000 to 2017, the urban population of Guizhou Province increased while the rural population decreased. Urban and rural construction land area also expanded during this time. From 2000 to 2008, the relationship between population change and construction land was strong negative decoupling. The relationship between rural population and rural construction land in Guizhou Province showed strong negative decoupling, while that between urban population and urban construction land showed expansive negative decoupling. With the decrease of rural population and increase of construction land, the relationship between rural people and land became unstable. Though both the urban population and urban construction land increased, the latter increased faster than the former.[Conclusion] The transfer of rural homestead land should be promoted actively in Guizhou Province so as to improve the level of intensive use of land for urban and rural construction. Integration of urban and rural areas should also be encouraged.

Abstract:[Objective] The spatial coupling relationship between the ecosystem service value and regional economy was analyzed to provide the basis for coordinated development of environmental protection and social economy in rocky desertification areas.[Methods] Based on the grid scale, the coupling coordination model was used to quantitatively evaluate the degree of coordinated development of ecological service value (ESV) and gross domestic product (GDP) in Panzhou City of Guizhou Province.[Results] ① The ESV "hot spot" area was mainly distributed in the minority villages and towns in the northeast, and the "cold spot" area was mainly distributed in the areas with rapid economic development and high urbanization rate. ② The spatial distribution of GDP in Panzhou City was characterized by its local high, and the high-value areas were mainly concentrated in industrial towns or economic and cultural centers, such as Shiqiao Town, the Yizi Subdistrict, and the Hanlin Subdistrict. ③ The overall distribution of ESV and GDP coupling coordination in Panzhou City was low, there was evident autocorrelation in the space, and the regions with low coupling coordination were mainly distributed in the southeast, north, and central parts of Panzhou City. ④ The type of coupling coordination between ESV and GDP in Panzhou City was mainly a severe imbalance type, accounting for 79.95% of the total area of the region.[Conclusion] Considering the low degree of spatial coupling of ESV and GDP in Panzhou City, balancing environmental protection and economic development would help to improve the coordination.

Abstract:[Objective] The ecological risk level and its temporal and spatial evolution processes based on the change in the landscape pattern in Yongchuan District, Chongqing City were analyzed to provide a scientific and theoretical basis for the optimization of land structure and ecological spatial development.[Methods] Taking an administrative village as the study area, the inflection-point method was used to determine the suitable spatial grain. Subsequently, the landscape pattern index was incorporated to develop an ecological risk index. Furthermore, spatial autocorrelation and "hot spot" analysis were used to study the temporal and spatial evolution of the landscape ecological risk in Yongchuan District.[Results] ① The suitable spatial grain of the landscape pattern analysis in Yongchuan District was 60 m. ② During the study period, the ecological security situation of Yongchuan District improved. The low-level risk areas extended southeast and southwest around Chashanzhuhai Street, and the high-level risk areas expanded outward around Wujian and Baofeng Town. ③ The Moran's I values of the spatial distribution of ecological risk were 0.447 2, 0.444 6 and 0.372 2, which indicated the clustering of research units with similar ecological risk. The high-high aggregation defined as the hot spots was distributed in the form of clusters in the northwest, southwest, and south of Yongchuan District and had expanded. The low-low aggregation defined as the "cold spots" extended southeast with Chashanzhuhai Street in bands.[Conclusion] Although the ecological security situation in Yongchuan District was improving, the ecological risk of towns near the urban perimeters and administrative boundaries has fluctuated greatly. Thus, these areas should receive more attention in future ecological governance.

Abstract:[Objective] The coal gangue mountains, the occupied land, and the surface vegetation destroyed by coal mining were analyzed to classify the types of coal gangue site properly. The objective of the study was to provide a basis for ecological restoration and reconstruction of mining areas.[Methods] The coal gangue in the Ningdong mining area was taken as the research object. Ten site factors were investigated and analyzed for microtopography, altitude, thickness of covering soil, and soil texture. Methods such as principal component analysis and cluster analysis were used to classify coal gangue mountain site types.[Results] The dominant factors were determined by principal component analysis as microtopography, thickness of covering soil, and soil texture. Afterwards, according to the dominant factors, the coal gangue mountains in the Ningdong mining area were classified into three site type groups, five site type subgroups, and eight site types through cluster analysis for various areas. The coal gangue platform had a large area, with slopes between 32° and 40°, and the thickness of the coal gangue overburden was > 30 cm. The soil field water capacity was between 16.82% and 34.85%, and the total K content was between 34.29 and 46.61 g/kg, which was extremely high. The total P content was between 0.31 and 0.62 g/kg, which was medium to low level. However, soil organic matter and total N content were at very low levels, and the soil of the coal gangue was more alkaline.[Conclusion] The reconstruction of gangue in Ningdong mining area should take measures according to local conditions. When gravel is less in overlaying soil, the arbor-shrub mixed pattern is selected with arbor based, or shrub pattern, or shrub grass pattern with shrub based. Whereas, the shrub grass pattern with grass based is selected when gravel is more. When the soil is light gravel, grass seeds are sown.

Abstract:[Objective] The water quality in the upper area of Qingshan Lake in Huangshi City, Hubei Province was monitored and analyzed to provide a basis for its ecological restoration.[Methods] Taking No.1 area of Qingshan Lake as a case study, using a comprehensive trophic status index, the state of eutrophication in upper area of Qingshan Lake was evaluated, and the nitrogen and phosphorus balance was estimated according to the material balance principle.[Results] ① The concentration of total nitrogen and total phosphorus reached 2.45 and 0.200 mg/L, respectively. ② The water quality of Qingshan Lake reached a level of moderate eutrophication. ③ The input of P and N mainly came from the upper stream. ④ The total input amount of N was 6 115.40 kg per year, and the total output amount of N was 1 939.51 kg per year. ⑤ The total input amount of P was 411.14 kg per year, and the total output amount of P was 198.21 kg per year. ⑥ The rates of retained N and P were 68.28% and 51.79%, respectively.[Conclusion] According to the results, to prevent the eutrophication of Qingshan Lake, an ecological floating bed for the upstream water should be adopted, which will simultaneously purify the water and improve the landscape. In the lake water area near the discharge outlet, high-efficiency in situ enhanced purification measures could be adopted.

Abstract:[Objective] The dynamic changes of soil erosion intensity and its spatial distribution in the source region of the Yellow River during 1999-2018 were studied to provide data for ecological environment construction and soil and water loss management in the region.[Methods] The dynamics of soil erosion in the region were analyzed based on the monitoring data in 1999, 2011, and 2018.[Results] Compared with 1999, the areas of soil erosion increased to 1.89×10⁴ and 1.01×10⁴ km² with an increase of 126% and 67.33% in 2011 and 2018, respectively, indicating that the area of soil erosion had increased in 2011 and then decreased until 2018. From 1999 to 2018, the area without any change in soil erosion intensity grade accounted for 77.97%, and the areas with decrease and increase in soil erosion intensity grade were 19.33% and 2.70%, respectively.[Conclusion] The increasing area of soil and water loss can be attributed to climate warming and drought, and grassland degradation was caused by unreasonable human activities. A number of major ecological protection, restoration and construction work should be carried out to improve the quality of degraded grassland and regional ecological environment.

Abstract:[Objective] To determine the technology requirements for an exclusive project of gully erosion control in a mollisol areas of Northeast China, the gully erosion control practices and models were investigated and summarized, in order to provide technical support for gully erosion control in the mollisol areas in Northeast China.[Methods] Sky and Earth integration and on-site investigation methods were used to obtain the morphological characteristic parameters, image data, and spatial information of gullies controlled by different periods. The gully erosion control practices and models and their effects were investigated.[Results] The gully erosion control practices in the mollisol areas of Northeast China were composed of three types:gully head protection, such as willow falling and stone masonry; gully bed stabilization practices, such as willow watercourse and gabion check dams; and arbors and shrubs providing mixed gully bank protection. The limitations of the existing control practices were identified and improved. The models of gully erosion control were divided into four categories:engineering assisted by vegetation, vegetation assisted by engineering, vegetation, and reclamation.[Conclusion] The current control methods of gully erosion in the mollisol areas of Northeast China achieved remarkable effects, forming mature control models and diversified control practices. However, the phenomena of unjustified models and inappropriate practices existed, and construction quality control and conservation after gully erosion control should be emphasized.

Abstract:[Objective] The advancement and practicality of wet-spraying vegetation-compatible concrete (VCC) were studied to provide a reference for ecological protection of engineering slopes.[Methods] The application of the new technology in the slope protection of a channel connected to Huama Lake in Ezhou City, Hubei Province, was presented. The effects of slope protection and soil and water conservation were observed. Furthermore, the plant coverage, plant density, average plant height, and species diversity index were tested on site.[Results] The technology could keep the slopes remained stable. The VCC substrate could adhere well to the slope surface, without forming gullies and slumps, with good soil and water conservation. The fundamental contradiction between the spraying of the VCC substrate and its adhesion to the slope surface was successfully solved. One month after the construction, the overall vegetation coverage of the slope reached more than 90%. The Shannon-Wiener diversity index, the Pielou evenness index, and the Simpson dominance index of the vegetation in the gentle-slope area were similar to those in the steep-slope area, but there were differences from the natural slope. The overall cost of the new technology (wet-spraying version) was 5%~15% lower than that of the old one (dry-spraying version).[Conclusion] As an upgraded version of dry-spraying VCC, this new technology shows significant advancements and can be used for ecological protection of engineering slopes.

Abstract:[Objective] Under the background of sponge city construction, building estates were studied to explore the control and utilization of the layout of a storage pool for rainwater runoff. The purpose was to provide technical guidance for the reconstruction of the old city sponge in the plain river network area, enhance the drainage and waterlogging prevention capacity, and improve the efficiency of rainwater utilization.[Methods] Taking the typical old estate of the Yanboyuan sponge reconstruction project in Jiaxing City as a case, a mathematical model of the drainage system was established based on storm water management model software. The optimal control water node was calculated by analyzing the relationship between the different rainfall recurrence periods and the water accumulation node in the study area. On this basis, the design rainwater control conditions were inputted, and the reasonable layout of the storage pool was explored.[Results] ① During the 5-15 years recurrence period, the distribution of the number of ponding nodes in the study area appeared to be in a stable period, and it reached the optimal level in the 9 years recurrence period. ② The ratio of the simulated volume to the storage pool between 20 and 100 m³ was 84%, and it had practical construction value. ③ After the suitable "low impact development plus storage pool" scheme was adopted, the effect of runoff control in the study area was evidently improved. The runoff peak reduction rate was more than 40%, and the coefficient of outflow runoff decreased by approximately 0.2. The miscellaneous water supply ratio was as much as 146.3%.[Conclusion] In the old urban areas in sponge transformation construction, we should pay attention to the rational layout and utilization of the storage pool to construct the runoff control system, combined with gray infrastructure and forestation, to attain efficient rainwater management.

Abstract:[Objective] The problems of vegetation degradation, difficulty in vegetation construction, poor water retention, and soil erosion in high and steep slope areas was studied to provide new ideas and reference for ecological restoration of high and steep slopes in semiarid regions.[Methods] Three types of vegetation construction technique were considered:anchorage frame planting bag tiling method (plot A), anchorage frame planting bag terrace method (plot B), and anchor cable frame terrace method (plot C). These three techniques were used to solve the problems of vegetation construction in the region and maintain the safety of construction and operation.[Results] ① The maximum vegetation coverage was 85% in plot A, and the plant species and number were highest. The coverages of plot B and plot C were 60% and 12%, respectively. ② The soil moisture content of soil layers between 0 and 20 cm was as follows:B (7.72%) > A (7.20%) > C (4.03%). At 0-2 cm layer, the soil moisture content followed A (5.82%) > B (3.95%) > C (2.88%), and at 2-10 cm and 10-20 cm layers, it was B > A > C. ③ The soil bulk density of soil layers at 0-20 cm was A (1.18 g/cm³) < B (1.24 g/cm³) < C (1.25 g/cm³). At 0-10 cm, it was B (1.23 g/cm³) > C (1.19 g/cm³) > A (1.15 g/cm³), and the bulk density was in a suitable state. At 10-20 cm, it was A (1.21 g/cm³) < B (1.25 g/cm³) < C (1.31 g/cm³), and the C area was in a tight state. ④ The order of soil erosion modulus was A (3 078 t/km²·a) < B (3 579 t/km²·a) < C (4 556 t/km²·a).[Conclusion] The construction technology of the anchorage frame planting bag tiling method can significantly improve vegetation growth, reduce soil erosion, and develop ecological restoration.

Abstract:[Objective] The effects of conservation tillage on soil wind erosion in an oasis irrigation area were studied. The role of conservation tillage of farmland in preventing and controlling soil erosion was evaluated to provide a theoretical basis for revealing related mechanisms.[Methods] Taking Minqin Integrated Desert Control Experimental Station in Gansu Province as a study area, based on field wind tunnel test, taking traditional tillage as the control, the effects of conservation tillage on the wind speed profile, sand flow structure (sediment discharge), and amount of wind erosion were analyzed.[Results] In conservation tillage, the wind speed near the surface decreased. At a high wind speed, the near-surface wind speed increased uniformly with the increase in height. This was different from the rapid increase in traditional tillage, preventing the sand flow structure from showing the "elephant nose effect." The decrease of sediment discharge was most evident at 0-20 cm, and the amount of soil wind erosion decreased. With the increase of the test wind speed, the decrease in the degree of wind erosion by conservation tillage was greater.[Conclusion] Conservation tillage could effectively prevent field soil wind erosion in oasis irrigation areas. The decreasing wind speed of standing stubble was maximum, and the sediment discharge and rate of soil wind erosion were low. The standing stubble method was easy to implement and is suitable for promotion and application.

Abstract:[Objective] The appropriate quantities of water and fertilizer were determined to understand their efficient utilization for walnut trees under drip irrigation in the Northwest Margin of Tarim Basin, which is a main production area of walnuts. The aim was to provide guidance for the extent of irrigation and nitrogen input to be used for drip irrigation for local dense planting of walnut trees.[Methods] The field experiment was conducted in the fruit trees experimental base of Xinjiang Agricultural University. Taking the nine-year-old dense planting of walnut trees (variety "Xinwen 185") as the research object, three irrigation levels (W₁:375 mm, W₂:435 mm, W₃:495 mm) and three fertilizer doses (F₁:2 250 kg/hm², F₂:4 500 kg/hm², F₃:9 000 kg/hm²) were arranged to study the effects of water-fertilizer coupling on walnut yield, walnut quality, and water and fertilizer utilization efficiency under drip irrigation. Mathematical models of the relationship between water-fertilizer investment and walnut indicators were established through multiple quadratic regression analysis.[Results] The effects of irrigation and fertilizer on the soil NO^-₃-N in the walnut tree growth periods of hard stone and oil conversion, on the walnut yield, quality, irrigation water use efficiency (IWUE), and partial factor productivity (PFP) reached significant levels (p<0.05). The interaction effects of irrigation and fertilizer on walnut yield, IWUE, and PFP reached significant levels (p<0.05). Hard stone and oil conversion periods were the key periods of fertilizer demand for walnut trees. The F₃ treatment resulted in the accumulation of soil nitrate nitrogen. There was no significant difference in the effects of W₂ and W₃ treatments on the quality, yield, and PFP of drip irrigation of walnut trees, which were significantly different from those of W₁. The effects of fertilizer application on the kernel yield, yield, IWUE, and PFP of walnut trees were significant.[Conclusion] Around Tarim Basin, the suitable ranges of water and fertilizer applications for the whole growth period of walnut trees were, 438 to 469 mm (including winter and spring irrigation) and 7 074 to 7 168 kg/hm², respectively, including 3 144 to 3 186 kg/hm² urea and 3 930 to 3 982 kg/hm² monoammonium phosphate.

Abstract:[Objective] This study quantitatively analyzed the specific situation of the infrastructure carrying capacity of Chinese national central cities from 2006 to 2017 to provide a scientific basis for promoting the development of national central cities.[Methods] The panel data of the infrastructure carrying capacity of national central cities from 2006 to 2017 were selected to construct an evaluation index system of the urban infrastructure carrying capacity from two levels:pressure and state. The entropy TOPSIS method and obstacle degree model were used to evaluate and diagnose the infrastructure carrying capacity and its obstacle factors for national central cities from 2006 to 2017. In addition, the status of the infrastructure carrying capacity was quantitatively measured and the obstacle factors were diagnosed based on the evaluation results of the infrastructure carrying capacity.[Results] From 2006 to 2010, the level of the infrastructure carrying capacity in national central cities generally increased significantly, and the growth rate of the infrastructure carrying capacity slowed down from 2011 to 2017. Specifically, the infrastructure carrying capacity in Beijing, Shanghai, Chengdu, Zhengzhou, and Xi'an cities increased significantly, whereas that in Guangzhou City was the smallest. The infrastructure carrying capacity also continued to increase as the population of the cities increased. The analysis using the obstacle degree model revealed that the main factors restricting the infrastructure carrying capacity in the national central cities were the per capita green space area, the per capita annual household water consumption, and the urban mobile phone penetration rate.[Conclusion] With the development of China's economy, the siphoning effect of central cities on the population is becoming increasingly intense. The per capita green space area, urban mobile phone penetration rate, and per capita annual household water consumption might be decoupled from a city's economy and population size, which would not be able to meet the daily infrastructure needs of the population.

Abstract:[Objective] The compatibility impacts of new sand-fixing materials on five typical herbaceous plants were studied to provide a theoretical basis for the ecological restoration and reconstruction of the Jiuzhaigou scenic area after an earthquake.[Methods] Based on the new sand-fixing materials of modified cellulose and typical herbaceous plants, matric suction analysis, vegetation simulation analysis, and relevant statistics were used to study the compatibility mechanism between sand-fixing materials of different proportions and herbaceous plants.[Results] The matrix suction of the sand-fixing material was stabilized at approximately 80 kPa, which could provide a stable water supply environment for plant root growth. Physalis alkekengi and Thalictrum aquilegifolium had germinated in two kinds of sand-fixing material, indicating that these two plants had good compatibility with the sand-fixing materials. From the distribution of the germination rate, T. aquilegifolium > P. alkekengi > Rubia membranacea, Rubia cordifolia, Prunella vulgaris, the germination rate of T. aquilegifolium reached 30%. A 1:3 liquid-solid mass ratio of sand-fixing material had a higher water content, and plant seedlings survived longer. The germination area of the seeds was at a position where the pores of the sand-fixing material were large.[Conclusion] The final matric suction of new sand-fixing material was within 80 kPa, the emergence rate of T. aquilegifolium with a 1:2 ratio of sand-fixing material was 30%, the average root diameter of P. alkekengi was 2 mm, and the sand-fixing materials with a certain porosity were more suitable for the growth of plant seedlings.

Abstract:[Objective] The dynamic changes of impervious surfaces were analyzed and monitored to provide a basis for urbanization and environmental quality evaluation.[Methods] Xi'an City was taken as the study area, and remote-sensing imagery of Landsat series in 1995, 2000, 2006, 2010, and 2016 were used to extract impervious surfaces by means of a linear spectral mixture analysis method. Subsequently, spatial-temporal changes of impervious surfaces during 1995-2016 and the driving forces were analyzed.[Results] ① The proportion of impervious surfaces in Xi'an City increased, with the average annual growth rate being the minimum from 2000 to 2006 and the maximum from 2010 to 2016. The maximum growth period in the main urban area was from 2006 to 2010. ② In terms of spatial changes, before 2006, the impervious surface was in a concentric pattern, with the main urban area as the core that radiated outward. After 2006, the impermeable surface of each district and county and the main urban area expanded greatly outward, showing one main center and multiple subcenter modes. ③ Population size, economic development, industrial structure, and planning policies were closely related to the increase of the impervious surfaces of Xi'an City.[Conclusion] The spatial-temporal changes of the impervious-surface expansion in Xi'an City basically reflected the planning requirements. In the future, the construction of a subcentral city should be strengthened, the ecological environment should be vigorously protected, and the relationship between urbanization and impervious-surface expansion should be handled properly.

Abstract:[Objective] A scientific and reasonable ecological security pattern was constructed in order to provide a reference for the coordinated promotion of sustainable development of regional land and space through ecological civilization construction.[Methods] Based on biodiversity, water resource security, and geological hazard avoidance, the importance of ecological land in Nanjing City of Jiangsu Province was quantitatively evaluated to identify ecological resources. A modified ecological resistance surface was constructed by considering the influence of PM_2.5 and nighttime light on species migration. A regional ecological security pattern was built by the minimum cumulative resistance model.[Results] The ecological resources of the 490.3 km² ecological land were identified, and the national and provincial nature reserves of Nanjing City were located within the ecological area. The identification results were reasonable. The revised resistance range of the ecological resistance surface was 0-43 854.6. The high-resistance area was located on the south bank of the Yangtze River, such as the Gulou, Qinhuai, and Eastern Jianye Districts. The low-resistance area was located in the center of Pukou, Xuanwu, and the northeast of Jiangning District. The revised resistance could characterize the differences of the regional ecological processes accurately. Relying on the core components of the ecological resource areas, buffer zones, and ecological corridors, the ecological security pattern framework ("one belt, three zones, and multiple axes") of Nanjing was established.[Conclusion] The improved method of constructing an ecological security pattern was effective, and the established ecological security pattern framework is consistent with the existing main function zone implementation plan of Nanjing City.

Abstract:[Objective] The changes and driving factors of the suitability of human settlement on the temporal and spatial scale were studied in order to provide theoretical basis for urban construction and improvement of living environment.[Methods] Jiangsu Province was selected as the research object. An evaluation index system composed of four dimensions:social, economic, ecological, and construction environment was constructed, and entropy, trend analysis, and geographical detector methods were used to quantitatively evaluate the suitability of living environment in 65 counties in Jiangsu Province in 2009, 2013, and 2017.[Results] ① The spatial differentiation of the suitability of human settlements in Jiangsu Province was significant, and was overall "locally contiguous" with a gradual decline from south to north. In terms of spatial change, the spatial stratification degree of the suitability of living environment declined significantly from south to north, and the trend of the contiguous distribution in the medium-high level, medium level, and low-level areas weakened. ② The average score and variation coefficient of the suitability of living environment in Jiangsu Province in 2009, 2013, and 2017 were 0.432, 0.475, 0.494 and 0.179, 0.192, 0.165, respectively. The score of suitability of living environment increased in 95.38% counties, and the regional difference in residential environment decreased at the end of the study. During the study period, the suitability of the living environment of the counties in Southern Jiangsu Province was relatively stable, while that of the counties in Middle and Northern Jiangsu Province fluctuated significantly. ③ Geographical exploration showed that the economic, social, and construction environment was the main driving factor behind the evolution of the suitability of living settlements in Jiangsu Province, while ecological environment was the secondary driving factor.[Conclusion] To improve the living environment, Jiangsu Province should expand the economic scale, stimulate the consumption level, promote the economic development and equalization. Meanwhile, the government should strengthen the construction of living environment by alleviating the aging crisis, strengthening the flow of regional population and resources, reducing the discharge of industrial pollutants, and improving the air quality.

Abstract:[Objective] The distribution of production, living and ecological space in Duyun City, Guizhou Province, was studied to provide theoretical guidance for the sustainable development, county-level land planning, and conservation of environment in karst areas.[Methods] Lorenz curves, Gini coefficients, and transition models were used for the comprehensive study of the production, living and ecological space in Duyun City from 2009 to 2018.[Results] ① In 2018, ecological space constituted 69.19% of the total area, followed by production space, which accounted for 26.87% of the total, and living space accounting for the smallest percentage, which accounted for 3.94%. ② From 2009 to 2018, the areas of production space and the ecological space showed a downward trend, whereas that of living space showed an upward trend. In terms of secondary space transfer, the increased areas of urban and rural living space came from agricultural production space and forest ecological space, and urban development occupied a part of forest land resources and agricultural resources. ③ In terms of Lorenz curves and Gini coefficients from 2008 to 2019, ecological space and production space were evenly distributed. Whereas, compared with the other two types, the curve of living space diverted farther away from the line of perfect equality, showing a concave curve. Gini coefficients from 2009 to 2018 were between 0.3 and 0.4, and the distribution of living space was basically reasonable. ④ From the perspective of location entropy, areas with an advantage of ecological space were mainly concentrated in the western part of the study area, areas with an advantage of living space were mainly concentrated in the central part of the study area, and areas with an advantage of production space were mainly concentrated in the southern and eastern part of the study area.[Conclusion] The three types of space were appropriately distributed in Duyun City, with ecological space as the dominant type. Future urban construction should be premised on the preservation of ecological space, with planning for urban development while limiting the use of ecological land.

Abstract:[Objective] The effects of parcel-border features (PBFs) on the calculation of the slope length factor and soil erosion rate of small watersheds in a black soil region were studied in order to provide a basis to improve the precision of soil erosion prediction in the region.[Methods] Two typical small watersheds were selected. Field survey and digital elevation model analysis were used to calculate the slope length factor considering the PBF, and the PBF was ignored.[Results] The slope length factor could be overestimated by 18% and the soil erosion rate by 31%, on average.[Conclusion] It is necessary to consider PBFs for the slope length factor and soil erosion rate calculations of small watersheds in black soil region. Similarly, under other factors, it would be necessary to consider PBFs when the slope gradients are larger and the intervals between cross-slope PBFs are smaller.

Abstract:[Objective] Considering the problems of uneven settlement, salinization, dam piping, and other disasters caused by the difficulty of new land reclamation and drainage in gully areas of loess hilly regions, the drainage design method of a channel land consolidation project was explored to provide reference for drainage design in related fields in the future.[Methods] The Yangjuangou subbasin in Yan'an City, Shaanxi Province, was taken as the study area, based on the design criteria of the stormwater in a small basin. Indoor experimental results were combined with related design specifications. The subsurface drainage method combined gravel and blind ditch, and it was verified by the engineering design through post prototype observation.[Results] ① The new land drainage design had three cross-sectional areas of 1 m×0.5 m, with lengths of 60, 30, and 30 m, and a slope of 6%-10% of the underground blind ditches. The blind ditches were filled with gravel with particle size of 50-80 mm and wrapped with nonwoven geotextile. Blind ditch drainage was collected by the retaining dam in the downstream leeches and was utilized.② Initial monitoring in the field indicated that, in the case of a subrainfall of 54.2 mm, compared with the new land without any engineering measures, the gravel blind ditch drainage project could reduce the increase in soil moisture content and conductivity of new land by 46.81% and 3.61%, respectively.[Conclusion] The drainage design using gravel blind ditch could effectively alleviate the water storage and salinization degree of new land soil in the channel, thereby improving the risk-response capability.

Abstract:[Objective] The growth and water utilization of dry farmland oats after the combined application of super absorbent polymer and microbial fertilizer were investigated, in order to provide an effective water-retaining and fertilizing measure for the crop production in Inner Mongolia of the Loess Plateau.[Methods] Four treatments, including no application of water retaining agent and microbial fertilizer (CK), single application of water retaining agent (A), single application of microbial fertilizer (M), combination of water retaining agent and microbial fertilizer (AM), were set up in the dryland area of the Loess Plateau, and the changes of soil water content, oat growth conditions, water consumption, yield composition and water use were analyzed.[Results] ① The combined application of super absorbent polymer and microbial fertilizer promoted the growth and development of oats. Taking the filling stage as an example, the plant height was increased by 3.27%-25.96%, the plant leaf-area was increased by 7.94%-23.06%, and the accumulation of aboveground dry matter was increased by 11.48%-21.88%. ② The combined application of super absorbent polymer and microbial fertilizer increased soil water content of 0-20 cm soil layer by 5.89%-11.50%, compared with no application. It significantly decreased soil water storage consumption by 7.70%-18.76% and reduced the total water consumption by 0.46%-1.26%. ③ The combined application of super absorbent polymer and microbial fertilizer promoted the formation of oat grains and biological yield, and thus promoted water use efficiency. The grain yield increased by 8.40%-20.12%, the biological yield increased by 10.80%-25.09%, and water use efficiency increased by 12.19%-26.80%.[Conclusion] The combined application of super absorbent polymer and microbial fertilizer can significantly promote the growth of oats in dryland, improve soil moisture status, conserve soil and water, and thus increase the yield of oats and improve the water use efficiency.