Abstract:[Objective] We studied the effects of vegetation restoration on soil physicochemical properties, enzyme activities, and fungal community of reconstructed soil in mining area of the Loess Plateau, to evaluate the effects of vegetation restoration on soil ecological restoration.[Methods] In Jungar Banner of Inner Mongolia Autonomous Region, three typical types of vegetation restoration (shrubs, arbors, and herbs) and unreclaimed land for sampling (0-20 cm) were chosen. The diversity and community of the soil fungi were analyzed using a high throughput, and the important factors affecting the community diversity of the fungi under different vegetation restoration managements were discussed in combination with the physicochemical properties of soil.[Results] ① Compared with unreclaimed land, the three typical vegetation restoration types, not only improved the soil physicochemical properties and enzyme activities significantly, but also improved the soil fungal operational taxonomic units (OUTs) and diversity index with significant differences, among which shrubs had the best effect. ② The relative abundance of the main phyla of fungi had a trend as follows:Ascomycota > Basidiomycota > Glomeromycota, and the sum of those phyla was more than 50% of the community. The community structure of the soil fungi remained stable among the four sampling sites. ③ The soil water content was the main factor affecting the structure of the fungal community.[Conclusion] Vegetation restoration affects the soil physicochemical properties, enzyme activities, and fungal community diversity. Ecological restoration in mining area of the Loess Plateau is a long process, in which shrubs should be planted to improve the ecological environment of the reconstructed soil.

Abstract:[Objective] The potential impacts of artificial vegetation reconstruction of desert steppe on regional evapotranspiration were studied in order to provide a theoretical basis for regional ecological restoration and reconstruction.[Methods] Based on the MODIS ET and NDVI products from 2001 to 2018, trend analysis, correlation analysis, and zoning statistics were used to study the effects of artificial vegetation reconstruction on regional ecosystem evapotranspiration, with the desert steppe in Yanchi County of Ningxia Hui Autonomous Region being used as an example ecosystem.[Results] ① The NDVI value in Yanchi County showed an upward trend from 2001 to 2018, with the growth rate reaching 0.006 0/a, and the growth area of the desert steppe in Yanchi County reached 98.55%. ② In 2001-2018, the average evapotranspiration (ET) was 266.73 mm, which showed that the ET in the southwest was higher than that in the northwest. The evapotranspiration in Yanchi County increased significantly over the past 18 years (p<0.01), with a growth rate of 6.27 mm/a. The ET has a noticeable upward trend in all pixels of Yanchi County. ③ The ET increased notably after large-scale artificial vegetation reconstruction in Yanchi County, and the ET and NDVI showed a significant positive correlation. The correlation between the changes in the ET and NDVI was 0.76 (p<0.01). ④ Vegetation structure change caused by vegetation reconstruction leads to greater evapotranspiration of the ecosystem, more water consumed in the desert steppe area of Yanchi County, and an accelerated growth rate of the ET.[Conclusion] The artificial vegetation reconstruction of the desert steppe has increased the NDVI value and enhanced the ET of the regional ecosystem in Yanchi County. The increased water consumption will affect the stability of the desert steppe ecosystem.

Abstract:[Objective] The soil nutrient status of dam land and terrace in a loess hilly area was studied to provide a scientific basis for the rational utilization of land resources, and restoration and improvement of the ecological environment.[Methods] The characteristic evolution of soil nutrients of dam land and terrace was studied in contrast to a barren slope in the Nianzhuang Gully watershed of Yan'an City, Shaanxi Province.[Results] The content of rapidly available phosphorus (AP), rapidly available potassium (AK), organic matter (OM), total phosphorus (TP), and total potassium (TK) was found in the order of terrace > dam land, whereas the total nitrogen (TN) content was of the order of dam land > terrace. AK and TK were found at medium variation levels, whereas the other soil nutrients were at higher variation levels. In the 80 cm section, the AP, AK, OM, and TN in the dam land and terrace displayed phenotypic characteristics, and the distribution of the TP and TK profiles was uniform. In the horizontal position, the nutrient content of the dam tail and uphill terrace was higher than that of the other positions, and fertilizer performance was better. With an increase of the years of utilization, the nutrients found in the terrace (except for TK content) showed a significant trend of a decrease at first and then an increase. The AP, TN, and TP content of the dam land showed the same trend of a decrease at first and then an increase, whereas AK, OM, and TK content of the dam land showed an increase trend at first and then a decrease. The critical year (45~50 years) of the degradation of soil nutrient change in the dam land lagged by at least 15 years that of the terrace (approximately 30 years).[Conclusion] At present, except for TK, the TP, TN, and OM content of dam land, terrace, and barren slope are in short supply. Thus, regular attention should be paid to the condition of soil nutrients close to the turning point and targeted supplementary fertilizer should be added promptly to extend the land use life via reasonable management measures and the promotion of the sustainable development of farmland. Compared with dam land and terrace, the soil nutrients in the barren slope were the highest, the fertilizer supply performance was the best, and the coefficient of variation was the smallest. However, the profile distribution was not uniform and required soil preparation.

Abstract:[Objective] Variations in the interannual and intra-annual runoff of the Pearl River basin from 1960 to 2017 were analyzed in order to provide reference for rational use of watershed resources.[Methods] We used the interannual variation coefficient (C_v) of the runoff, the M-K trend analysis and the Morlet wavelet to analyze the interannual variations in runoff. Meanwhile, we used concentration (period) and runoff contour method for runoff within a year.[Results] The interannual variability of runoff in the Pearl River basin was small and the runoff stability was high. The total runoff had not changed significantly. The change in runoff was coinciding with droughts and floods in the Xijiang and Dongjiang river basins were relatively uniform and the incidence was low, the Beijiang river basin was prone to flood disasters. The runoff in Xijiang, Beijiang, Dongjiang, rivers of the Pearl River basin was basically 25~32, 10~20, 4~10 years. The distribution of runoff in the Pearl River basin was extremely uneven during the year, and in the annual runoff concentration (RCD_year), the Xijiang river was slightly higher than Beijiang and Dongjiang rivers. In recent years, the RCD_year had decreased. The annual runoff concentration period (RCP_year) indicated that the maximum runoff of the Beijiang river alternated in May and June, and the maximum runoff of the Dongjiang river alternated in June and July, and the maximum runoff of the Xijiang river occurred mainly in July.[Conclusion] There is no obvious decline or upward trend of runoff in the downstream areas of the Pearl River basin from 1960-2017, but the interannual and intra-annual changes in runoff are still obvious. The main reason for the change is the vigorous human activities such as the construction of river basin reservoirs.

Abstract:[Objective] The soil reinforcement effect of root systems of Leucaena leucocephala and Coriaria sinnica was studied in Jiangjia gully, Dongchuan District, Kunming City, Yunnan Province in order to provide a theoretical basis and data support for the application of local biological and engineering methods to utilize the control benefit of debris flow.[Methods] The distribution characteristics of root systems were identified using the root digging method, the root tensile characteristics were analyzed with the root tensile test, and the added value of the root systems of the two plant species to the soil shear strength was calculated using the Wu-Waldron model (RWM).[Results] ① The root area ratio of both L. leucocephala and C. sinnica decreased with an increase in soil depth. ② The root configurations of L. leucocephala and C. sinnica were vertical type and transverse type, respectively. ③ The relationship between the tensile strength and root diameter of C. sinnica roots was a decreasing logarithmic function, whereas there was no obvious regularity between tensile strength and root diameter for L. leucocephala roots. ④ The added value of the shearing strength of both L. leucocephala and C. sinnica roots decreased with an increase in soil depth. The depth of soil reinforcement of L. leucocephala and C. sinnica roots was approximately 1.4 m and 0.6 m, respectively.[Conclusion] Both root systems of L. leucocephala and C. sinnica played a significant role in soil fixation. Because the root architecture, soil reinforcement depth, and soil reinforcement technique of these two plants were different, utilizing these two species together can improve slope stability and soil anti-scourability.

Abstract:[Objective] The change in the water content of meadow soils at different depths with different plow and straw returning methods was studied to provide a theoretical basis for formulating scientific/reasonable tillage and fertilizer technology according to local conditions during future production.[Methods] Based on field experiments, the soil water content, field water holding capacity, and bulk density of crop growth different stages and different soil depths were studied using three tillage and straw returning methods, which were no-tillage, shallow plow, and deep plow, each partnered with no straw and straw returning.[Results] The inter-annual variation in the soil water content had relationships with the annual precipitation and precipitation variability. In two consecutive years of no-tillage, the soil water curves were basically the same, the field water holding capacity in the 0-20 cm layer decreased by 13.62%, while the shallow and deep plow increased the field water holding capacity by 11.32% and 27.98%, respectively. The influence of the soil water content at the depth of 20-30 cm was higher than other soil layers, and along with the crop growth and increase of ground cover, the soil water in the three tillage systems decreased under the 40 cm soil layer. With straw shallow and deep returning, the water holding capacity of the 0-20 cm arable layer saw an average increase of 16.24% and 5.08%, respectively, and the soil bulk density decreased by 0.12 g/cm³ and 0.09 g/cm³, respectively.[Conclusion] Within the same plow systems, the soil water content with straw returning was higher than that without, and the less precipitation that was present the more obvious this difference was. Compared with no-tillage and straw mulching, the soil water increased with plow and straw returning, which increased the drought resistance of the crops and yields.

Abstract:[Objective] The adaptation mechanism and cost of Robinia pseudoacacia under different site conditions in the loess hilly and gully area of the Loess Plateau were studied to provide support for vegetation restoration in this area.[Methods] By investigating the variations in the functional traits and growth performance of R. pseudoacacia at sites with different slope aspects and positions, we analyzed the main factors affecting the growth of R. pseudoacacia in a heterogeneous environment in the loess hilly and gully area.[Results] ① The leaf nitrogen content, leaf phosphorus content, leaf organic carbon content, root phosphorus content, root organic carbon content, and root tissue density of R. pseudoacacia were higher on sunny slopes than on shady slopes. With a change in the position of the slope from a lower to a higher position, the leaf nitrogen content, leaf phosphorus content, leaf organic carbon content, root phosphorus content, root nitrogen content, specific leaf area, and leaf thickness decreased, while the root organic carbon content and leaf tissue density increased; ② Significant relationships were found between the functional traits of R. pseudoacacia and environmental factors, with the soil factors exerting the most influence. A trade-off between functional traits has been found, not only within the same organ, but also among different organs; ③ The plant height, diameter at breast height (DBH), ground diameter, and crown width of R. pseudoacacia was larger on sunny slopes than on shady slopes and decreased significantly with a change in the slope position from lower to higher. Meanwhile, a significant relationship was also found between the growth and functional traits of R. pseudoacacia.[Conclusion] On sites at lower positions with a south-facing aspect, R. pseudoacacia has a lower adaptation cost and can bring about greater ecological benefits.

Abstract:[Objective] The effects of vegetation root content on the shear strength of mountain red earth acquired from vegetated slope in Chenggong district, Kunming City of Yunnan Province were analyzed in order to provide theoretical basis for relevant research.[Methods] The shear strength tests were carried out by preparing roots-soil complex samples with four levels of root content:0 (no root samples), 0.467, 0.93, 1.4 mg/cm³, as well as five levels of soil moisture content (20%, 25%, 30%, 35%, and 40%).[Results] The vegetation roots were found to provide soil with additional shear strength and helps soil resist deformation, which can enhance its shear strength. Vegetation roots had obvious enhancement effect on the shear strength of soil, but this enhancement effect was limited. When the root content was 0.93 mg/cm³, the root system had the best enhancement effect on the shear strength of soil. With an increase in root content, the cohesion and the angle of internal friction always presented a negative correlation. In the case of low water content, the cohesion first decreased and then increased, while the angle of internal friction changed inversely with the change of root density. When the soil moisture constant and the root content was low (water content and root content less than or equal to 35% and 0.93 mg/cm³ respectively), the soil participated in the whole process of shear and they were the main object to be sheared, and the calculated cohesion and internal friction angle were both positive, which was consistent with Coulomb's law. When the soil moisture and root content was high(water content and root content was 35% and 1.4 mg/cm³ respectively or the root content was 45% and root content was greater than or equal to 0.467 mg/cm³), the shear object was mainly the root system, and the cohesion calculated by Coulomb's law was negative, which does not conform to Coulomb's law.[Conclusion] Coulomb's law is not applicable to the study of the shear strength of the root-soil complex which has high water content and vegetation density. When using vegetation for slope protection, it is necessary to carry out experiments to determine the optimal root and water content of the slope soil to produce the highest shear strength.

Abstract:[Objective] Identifying the variations in soil respiration and its influencing factors, to provide the basis for evaluating the carbon sequestration resulting from converting cropland to apple orchards on the Loess Plateau.[Methods] A field experiment was conducted in a mature apple orchard at the Changwu State Key Agro-Ecological Station, Shaanxi, China. Soil respiration, soil temperature, and soil moisture (θ) were periodically measured in situ for three years by an automated soil CO₂ flux system (Li-COR, Lincoln, NE, USA).[Results] Soil respiration exhibited very significant seasonal and annual variations. The highest values for soil respiration were 3.14, 3.98, and 4.71 μmol/(m²·s), which appeared during the rainy season (July to September); the lowest soil respiration value appeared in November, at 0.99, 0.88, and 0.69 μmol/(m²·s) for three years; and the coefficient of variation for the cumulative soil respiration was 21%. Soil respiration and soil temperature followed an exponential relationship, and the soil moisture significantly influenced the soil respiration and temperature sensitivity of soil respiration(Q₁₀) values. Soil respiration was 2.01 μmol/(m²·s) when θ< 11.12%, while it increased to 2.24 μmol/(m²·s) when θ ranged from 11.12% to 23.63%, and decreased to 1.38 μmol/(m²·s) when θ> 23.63%. The Q₁₀ value was 1.57, 1.63, and 1.38 when θ<11.12%, 11.12%<θ<23.63%, θ> 23.63% at the apple orchard.[Conclusions] Soil moisture significantly influences soil respiration and Q₁₀. This study is useful for estimating the soil carbon sequestration in orchard ecosystems on the semi-arid Loess Plateau.

Abstract:[Objective] The characteristics and relationships of hydrochemistry in soil infiltration water (SIW) were studied in order to reveal the relationship between the changing ratios of Ca, Mg, and Sr in the karst water and the climate outside the cave.[Methods] Regularly monitoring, sampling, and experimenting on the four cave water pots and the overlying three SIW points in Mahuang cave, Suiyang County, Guizhou Province. Then, statistical analysis methods and comparative analysis of various monitoring indicators by the element ratio method were used.[Results] ① The main hydrochemistry indexes of the SIW showed dry season > rainy season, whilst the cave water showed the opposite characteristics. ② The concentration of EC, Ca²⁺, Mg²⁺, HCO₃^-, and Sr²⁺ in the cave water was about 2~6 times higher than that of the SIW, which indicated that the karst process in epikarst had an important influence on the hydrochemistry elements in the cave. ③ The SIW had a positive response to surface rainfall and temperature changes, the large amounts of mineral elements retained in the soil during the dry season was the main reason for the high concentration of Ca, Mg, and Sr in the SIW in April. ④ The ratios of Mg/Ca and Sr/Ca in the cave water and their correlations reflected the synergy of the cave water by source, water-rock interaction, dewatering deposition of the cave water, prior calcite precipitation (PCP) process, and the main karst process of cave overlying. Therefore, the ratio changes can indirectly show the temperature outside the cave and changes in rainfall.[Conclusion] The hydrochemistry of the SIW and cave water have obvious characteristics of seasonal changes, there are differences between the monitoring pots, and there are significant differences between the monitoring points. The changes in the Ca, Mg, and Sr ratios of the two types of water and their correlations have positive responses to surface rainfall and temperature changes.

Abstract:[Objective] Chlorophyll fluorescence characteristics of Bothriochloa ischaemum in response to soil water periodical change were studied in order to provide a theoretical basis for the rational utilization of forest and grass measures for soil and water conservation in loess hilly regions.[Methods] Seven mixture ratios (B. ischaemum to Lespedeza davurica, 0:12, 2:10, 4:8, 6:6, 8:4, 10:2, and 12:0) and three soil water regimes[HW 80%±5% of field capacity(FC), MW 60%±5% of FC, LW 40%±5% of FC)] were set in the pot experiment, and soil water content was reduced separately from HW to MW (H-MW) or from HW to LW (H-LW) during the heading period, flowering period, and mature period, respectively. Chlorophyll fluorescence parameters of B. ischaemum were measured at 0, 2, 4, 6, and 8 days after soil water reduced.[Results] Maximum photochemical efficiency (maximam fluorescence/variable fluorescence, F_v/F_m), active photochemical efficiency (Ф_PSⅡ) and apparent electron transport rate (ETR) showed decreasing trends with the water stress decrease, and those values decreased much more under H-LW-3. F_v/F_m and Ф_PSⅡ in the heading period or the flowering period were signicantly higher than in the mature period, and the F_v/F_m was larger than 0.750. Non-photochemical quenching (NPQ) showed increasing trends in the heading period and flowering period, and decreasing trends in the mature period, but the photochemical quenching (q_p) showed opposite trends during the growth period. After 8 days of soil water reduction, F_v/F_m and Ф_PSⅡ in the mature period under H-MW were signicantly higher than under H-LW, and F_v/F_m, Ф_PSⅡ, and ETR in the 12:0 mixture ratio were signicantly lower than in others under most water treatments.[Conclusion] The application of mixture planting enhanced the PSⅡ photochemical activity of B. ischaemum when intercropped with L. davurica under periodically decreasing soil water conditions.

Abstract:[Objective] The profile distribution of purple soil humus:humic acid (HA), fulvic acid (FA), and humin (HM), and soil nutrients:total phosphorus (TP), available phosphorus (AP), total nitrogen (TN), and available nitrogen (AN), under six different vegetation types in Longchuanjiang River basin were studied to provide a scientific basis for the maintenance of soil fertility.[Methods] Soil samples were collected from different soil horizons (0-10, 10-20, and 20-30 cm) at each sampling point using the zigzag method. Then, soil samples of each layer were evenly mixed and the removal of redundant samples was performed by quartering three times and the corresponding indicators were determined.[Results] The content of TP, AP, TN, AN, humus carbon, HM carbon, HA carbon, and FA carbon decreased with soil depth under the six vegetation types. The litter layer content was significantly higher than that of the other layers (0-10, 10-20, and 20-30 cm). There was no significant difference in soils among the different vegetation types. The humus and its composition in the orchard soil were significantly higher than that in the Eucalyptus forest, which was characterized by orchard > deciduous broad-leaved forest > warm temperate coniferous forest > coniferous and broad-leaved mixed forest > shrub > Eucalyptus forest. Correlation analysis showed that the humus components had very significant positive correlations with soil organic matter, TP, AP, TN, and AN.[Conclusion] Soil humus and its components in orchards and deciduous broad-leaved forests are significantly higher than those in other vegetation types, and there is a significant positive correlation between humus and soil physical and chemical properties.

Abstract:[Objective] The effects of different root treatments on the growth performance of Pinus densiflora var. zhangwuensis were studied in order to provide a science-based method to boost afforestation in the Beijing City.[Methods] A completely randomized block experiment was conducted in Miyun District of Beijing City. The experiment was conducted to study the effects of different treatments on the survival rate, growth rate, leaf traits, dry matter content of 5-year-old Pinus densiflora var. zhangwuensis, including compound microbial agent, ABT-3 rooting powder and a 1:1 mixture of the two treatments.[Results] When applying the ABT-3 rooting powder alone, the ground diameter, underground biomass, afforestation survival rate and afforestation cost were the best; when applying compound microbial agents alone, seedling height, ground diameter, annual average growth, dry matter quality on the ground, the total dry matter quality, needle thickness, needle area and chlorophyll content were the best of all; The measured indexes of the mixed treatment were lower than the single treatment, but higher than the control treatment.[Conclusion] In the afforestation of Pinus densiflora var. zhangwuensis in Beijing City, in addition to the conventional tending management, the use of compound microbial agents may not only improve the survival rate of afforestation, but also promote the growth and development of seedlings, accelerate the pace of forestation, and improve the stand quality, and ultimately achieve the goal of improving the environment of the Beijing City.

Abstract:[Objective] The water conservation ability of the litter and soil layers of Alnus formosana mixed plantations was studied in order to provide a theoretical basis for the rational management and utilization of A. formosana in the Guangxi Zhuang Autonomous Region.[Methods] The entropy weight method was used to comprehensively evaluate the hydrological effect related factors. The mixed modes included A. formosana and Pinus massoniana, A. formosana and Eucalyptus grandis×urophylla, A. formosana and Castanopsis hystrix, and an A. formosana pure plantation as the control.[Results] ① The maximum water holding capacities of litter were largest in the mixed A. formosana and C. hystrix plantation with a 2:1 ratio and least in the mixed A. formosana and P. massoniana plantation with a 1:1 ratio. The effective retention rate of litter in the mixed A. formosana and C. hystrix plantation (with a 1:2 ratio) was the highest, the effective retention amount in the mixed A. formosana and C. hystrix plantation (with a 2:1 ratio) was the highest, whilst the effective retention rate and amount in the mixed A. formosana and E. grandis×urophylla plantation (2:1) were the lowest. ② The soil bulk density in the mixed plantations was significantly lower than that in the pure forest, however, the total porosity, capillary porosity, natural water content, maximum water holding capacity, and capillary water holding capacity of the soil were all higher in the mixed plantations. ③ The entropy weight method was used to calculate the weight value. The maximum water holding capacity of the litter was the largest, and the soil capillary porosity was the smallest. The comprehensive evaluation of the water conservation ability was ranked as follows:A. formosana and E. grandis×urophylla (1:2) > A. formosana and C. hystrix (2:1) > A. formosana and P. massoniana (1:2) > A. formosana and C. hystrix (1:1) > A. formosana and E. grandis×urophylla (1:1) > A. formosana and P. massoniana (2:1) > A. formosana and C. hystrix (1:2) > A. formosana and E. grandis×urophylla (2:1) > A. formosana and P. massoniana (1:1) > CK.[Conclusion] The water conservation ability of the mixed plantations of A. formosana was better than that of the pure plantation.

Abstract:[Objective] The effects of various soil physical and chemical properties on plant growth on canal slopes were studied in order to provide a scientific basis for grassland slope protection and standardized management of the central route of the south-to-north water transfer project.[Methods] The physical and chemical properties and change characteristics at different levels of the typical grass slopes of four different coverages were analyzed by taking the slope of the Xinzheng section of the central route of the south-to-north water transfer project as an example.[Results] ① The soil moisture in autumn was more suitable, with an average moisture content of 16.56% in the shallow layer and 16.91% in the deep layer; the vertical profile difference within the same sample plot was not significant, and the shallow layer difference of the different quadrat was obvious. ② The soil pH value was about 8.5 on average, and the soil was strongly alkaline. The average soil bulk density was about 1.37, and the soil bulk density in the shallow layers was lower than that in the deeper layers. ③ The average content of organic matter was 0.34%, and the average depth was 0.31%, which differed significantly (p<0.05) depending on coverage in the quadrat. The soil was found to be deficient in total nitrogen and phosphorus, and the total potassium content was relatively high.[Conclusion] There were obvious differences in soil characteristics, between different vegetation and degrees of grass slope protection, but all soil types were found to be of poor quality. Besides soil characteristics, the factors that affect the plant growth on canal slopes was also related to daily management and protection measures, such as lawn planting measures, the effects of long periods of extreme drought, and improper pruning.

Abstract:[Objective] Morphological characteristics, different orientation section profile characteristics, and erosion and deposition effects of concave surfaces of biodegradable poly lactic acid (PLA) checkerboard barriers with different sizes were analyzed to provide evidence on which to base the specification parameter selection of PLA checkerboard barriers.[Methods] The biodegradable sandbag checkerboard barriers laid on the edge of the Jilantai Salt Lake in the Inner Mongolia Autonomous Region were undertaken for research. The sizes of the checkerboard were 0.5 m×0.5 m, 1 m×1 m, 1.5 m×1.5 m, and 2 m×2 m. The shape of the concave surface was measured, pictures of the shape of the concave surface were drawn, and the parameters of the erosion and deposition after the wind period were calculated.[Results] A sand surface can form a stable concave surface for the four kinds of PLA checkerboard barrier. The center was lower than the surrounding parts in the PLA checkerboard barriers. The strengths of net deposition in the 0.5 m×0.5 m, 1 m×1 m, 1.5 m×1.5 m, and 2 m×2 m PLA checkerboard barriers were 17.29, 7.09, 0.61, and -8.2 g/cm², respectively.[Conclusion] Before the stable formation of the concave surface, the sand grains of the PLA checkerboard barriers of 0.5 m×0.5 m and 1 m×1 m were mainly deposition. The volume of erosion and deposition was close to equilibrium in the 1.5 m×1.5 m PLA checkerboard barriers. The sand surface was wind eroded at the initial stage in the PLA checkerboard barriers of 2 m×2 m, but when the sand surface formed a stable concave surface, the PLA checkerboard barriers could control wind erosion of the sand surface.

Abstract:[Objective] The measurement differences between an unmanned aerial vehicle (UAV) and traditional ground methods were analyzed, and the suitability of extracting the morphological characteristics of erosion gullies by UAV orthophotos in Tibet was studied in order to obtain the parameters of erosion gullies accurately and quickly, with the aim to provide basic information for the prevention and control of gully erosion in the area.[Methods] A total of 20 erosion gullies were selected from 6 research sites, to compare the lengths and widths of erosion gullies measured through field measurements and extraction from UAV orthophotos.[Results] Compared to the results from the field measurements, the mean deviation extent of the erosion gullies' length and width extracted by orthophotos was concentrated between 2%~5% and 0~40%, respectively. Additionally, when the measured width was in the range 400~1 000 cm, the deviation between the extracted and measured values was the lowest. Across the 6 research sites, there was no obvious relationship between the deviation extent of the erosion gullies' morphological parameters extracted by orthophotos and the location. The soil and vegetation near the gully shoulder lines and the grazing damage to the gully shoulder lines were the main factors affecting the extraction of the erosion gullies' morphological characteristics.[Conclusion] UAV remote sensing can provide a convenient and reliable data source for gully erosion monitoring in Tibet.

Abstract:[Objective] The use of a consumer unmanned aerial vehicle (UAV) was developed and evaluated to construct an engineering pile terrain model, that can provide data reference for urban soil and water conservation monitoring.[Methods] The consumer-level UAV DJI Elf 4Pro was used to perform vertical down photography and oblique photography of the land shape of a park under construction, and quickly construct a terrain model with different number of control points. Analysis of the relative accuracy was based on absolute accuracy, and a comparison of area and volume with approximate real values of two different aerial photography methods at different number of control points.[Results] ① The landform of the engineering pile with little terrain fluctuation was not suitable for 45° tilting aerial photography, it could increase the tilt angle to 70°; ② The overall accuracy of the vertical lower view aerial photography was better than that of the oblique cross aerial photography. The relative accuracy could reach the sub-meter level without the control point, and the earthwork measurement error was less than 5%; ③ Tilting aerial photography could improve elevation accuracy and earthwork measurement accuracy at rare control points, and the earthwork measurement error was less than 1% at five control points.[Conclusion] The construction of the engineering pile terrain model by the consumer UAV can achieve high precision with no control and rare control points. Quick, accurate, and 3D intuitive reflection of area and earthwork changes, it provides real-time and reliable data reference and decision-making basis for soil and water conservation program implementation and monitoring.

Abstract:[Objective] The temporal and spatial distribution characteristics and variation of soil salinity irrigated with magnetized water was explored in order to provide a theoretical basis for the magnetized water irrigation technology of coastal saline-alkali soil.[Methods] The coastal saline-alkali land of a Robinia pseudoacacia plantation in Dongying City was used as the research site to analyze the spatiotemporal distribution and evolution of soil salinity under four measures of freshwater irrigation (FW), magnetized freshwater irrigation (MFW), subsurface shallow brackish water irrigation (GW), and magnetized subsurface shallow brackish water irrigation (MGW).[Results] The two types of magnetized irrigation treatments (MFW and MGW) reduced the soil salinity in the coastal saline-alkali soil. The average salt content of the different irrigation treatments in the different soil layers followed the order:GW > CK(no irrigation) > FW > MGW > MFW and the soil salinity in the different soil layers decreased with an increase of soil depth.[Conclusion] ① Magnetization treatment significantly reduced the soil salt accumulation in the surface soil layer. Especially in the spring and autumn, the use of magnetized water irrigation can inhibit the return of salt to the soil, with the effect being more obvious in the 20-40 cm soil layer. ② Moderate irrigation by magnetizing subsurface shallow brackish water could save water resources for the region and effectively promote soil desalination in saline-alkali soils.

Abstract:[Objective] The return of Trifolium repens to an apple orchard was investigated to understand the effects on soil bacteria diversity in different degradation stages, and to provide theoretical basis for the utilization of T. repens in orchards and the promotion of pasture-planting in orchards.[Methods] Fresh T. repens was covered or buried in an apple orchard in Luochuan County, Shannxi Province. At 1, 3, 6 and 12 months of T. repens degradation, soil samples were collected, and high-throughput sequencing technology was performed to determine the diversity, richness and structure of soil bacteria.[Results] ① There were no significant differences in the diversity of preponderant bacteria after T. repens returning, but some richness was different. Acidobacteria, Euryarchaeota, Crenarchaeota, Spirochaetes and Nitrospira were found in the soil of the return treatment group. ② There were some remarkable differences in community distribution of soil bacteria (p<0.05), varying in different degrading period after the return of T. repens. The richness of Acidobacteria, Bacteroidetes and Proteobacteria increased, but that of Firmicutes decreased in soil samples from the two treatment groups compared with the control. ③ Over time, the richness of Gemmatimonas, Flavobacterium, Opitutu, and Arenimonas increased in groups in which T. repens had returned; however, the richness of Nitrospira, Neisseria, Pirellula, and Steroidobacter decreased.[Conclusion] Either covering or burying T. repens could optimize structure of soil bacteria community, increase probiotics abundance and improve the matter cycle in the microbial ecosystem.

Abstract:[Objective] The effects and interaction of nitrogen, phosphorus and water on the germination of a soil seed bank in vegetation restoration project were explored in order to provide valuable reference for the judicious utilization of topsoil and the control of key parameters on soil seed bank's vegetation recovery engineering.[Methods] The effect of three factors (nitrogen, phosphorus and water) on soil seed bank's germination and early seedling growth were studied using greenhouse germination experiments. Box-Behnken central composite design (BBC) combined with the response surface methodology (RSM) was used to explore the interaction effect of these three factors on the soil seed bank's germination and early seedling growth, and the optimal scheme of soil seed bank's vegetation restoration was obtained. Finally, the coupling effect of the three factors in the response surface model was verified by the dimension reduction method.[Results] ① With nitrogen, phosphorus and water content in the range of 5~20 g/m², 5~15 g/m², 10~30 mm respectively, the germination effect on the soil seed bank was the best in the single factor experiment; ② The quadratic model was selected in the response surface analysis, and the water had the most important influence on soil seed bank. The optimal conditions for the vegetation recovery was determined to be with levels of nitrogen of 13.54 g/m², phosphorus of 9.47 g/m², and water content of 30 mm respectively; ③ Plant uptake of nitrogen and phosphorus was relatively lower under low water content, in which the interaction of nitrogen, phosphorus and water content was not significant. In the case of higher water content, even if fewer fertilizers were applied, the germination effect on the corresponding soil seed bank was higher than that of the treatment with high fertilizer level but water stress. The water content was determined to be the most important factor in the research by the method of dimension reduction, which was consistent with the result of response surface analysis.[Conclusion] Optimal conditions may slightly different from the actual, but the research still has great reference value, and the interaction effect of nitrogen, phosphorus and water shows the promotion effect on soil seed bank's germination and early seedling growth.

Abstract:[Objective] We investigated the effects of different proportions of garden waste compost and bentonite for improving coastal saline soil. This was in order to formulate suitable amendments for solving the problems of high soil salinity and poor ecological environments in coastal areas.[Methods] Through field trials in a coastal area, changes in soil enzyme activity, microbial biomass carbon, and nitrogen in different treatment groups were measured, and their correlations with soil physical and chemical properties were analyzed. This was achieved by applying 68 kg/m³ compost garden waste (T₁) alone, 15 kg/m³ bentonite (T₂) alone, and a mixed application of compost garden waste and bentonite (T₃).[Results] The mixed application (T₃) had a more significant effect on increasing soil enzyme activity and microbial biomass carbon and nitrogen. Urease, sucrase, and dehydrogenase activities were 10.1, 9.0, and 4.5 times greater than the control, respectively. The soil microbial biomass carbon and nitrogen increased by 24.8% and 78.1%, respectively, compared to the control. In addition, mixed application could significantly improve the soil physical and chemical properties:soil salinity decreased by 62.7% and nutrient indicators increased by 57.2% to 101.4%. Inorganic amendments had less effect on soil enzymes and soil microbial biomass compared to organic amendments. The available potassium and available nitrogen were the main factors affecting soil enzymes and microbial biomass, whereas salt content and bulk density were negatively correlated with soil enzymes and microbial biomass.[Conclusion] The addition of garden waste compost played a decisive role in increasing soil enzyme activity and microbial biomass. The best application treatment group was 68 kg/m³ of garden waste compost with 15 kg/m³ of bentonite.

Abstract:[Objective] The effects of Bacillus and a plant growth regulator on the growth and development of moss biocrusts were studied in order to provide a scientific basis for improving the provenance propagation efficiency of moss biocrusts.[Methods] A two-factor complete experiment was designed to observe the coverage, height, and density of moss biocrusts under greenhouse conditions by selecting Bacillus(B. mucilaginosus/B. megaterium) and growth regulator (Thidiazuron, TDZ) as the two variables.[Results] ① The growth status was optimal after the addition of B. mucilaginosus, which increased the coverage (+18.9%), height (+0.85 mm), and density (+15.44 strains/cm) compared to the control group (no Bacillus and growth regulator). ② After the addition of B. megaterium, the density of moss biocrusts increased (+5.76 strains/cm²); however, the height decreased (-0.78 mm) and the coverage was not significantly changed. ③ Treatment with TDZ reduced the coverage (-11.78%) and height (-3.33 mm); however, it had no significant effect on the density of moss biocrusts. ④ The growth status of BSC was significantly affected by the interaction of Bacillus and TDZ. The combination treatment of B. megaterium and TDZ increased the density of moss biocrusts (+9.79 strains/cm²) and was higher than that of the treatment where only B. megaterium was added (+3.67 strains/cm²). Additionally, the combined treatment of B. mucilaginosus and TDZ increased the density of moss biocrusts (+4.3 strains/cm²); however, it weakened the positive effect of B. mucilaginosus (-11.14 strains/cm²).[Conclusion] The effects of functional microorganisms and a growth regulator on the growth and development of moss biocrusts are very significant, which should be considered during the practice of provenance propagation of moss biocrusts.

Abstract:[Objective] The effects of municipal sludge application on crop growth and quality were analyzed in order to provide a scientific basis for the direct land use of municipal sludge.[Methods] Using Zea mays as the experimental material, a field experiment was conducted with different modes of sludge applications (furrow application, spraying application, and application of sludge 20 cm below the surface soil) and dosages (30, 90, and 200 t/hm²) to investigate the effects of sludge application on maize growth and quality, and the accumulation of heavy metals in the soil.[Results] An appropriate amount of sludge can promote the individual growth of maize, plant height, biomass, and chlorophyll content in leaves, with the protein content of maize grain being significantly higher than that in the control when the dosage was 30 t/hm². Overall, the seed germination rate and grain yield were higher than those of the other two methods when the application of sludge occurred at 20 cm below the soil surface. When the dosage was 30 t/hm², the highest grain yield was 656.70 kg/667 m², which was 29.64% higher than that of the control. The concentrations of Cu, Zn, and Pb in the soil and the concentrations of Cu and Zn in the corn kernel increased gradually with increasing applications of sludge composts. However, there was no significant change in Pb content and the content of Cu, Zn, and Pb in the soil and corn kernel did not exceed the relevant national standards. Taking the concentration of heavy metals satisfying the soil environmental quality standard as the restriction condition, it was estimated that the ideal local municipal sludge application dosage was 30 t/hm², which could be applied continuously for 5 years.[Conclusion] The best environmental effect occurred when the sludge dosage was 30 t/hm²; thus, to reduce the stress effect caused by the local accumulation of sludge in soil, the application of the sludge 20 cm below the soil surface using the spraying application method was ideal.

Abstract:[Objective] A scientific basis for the development and utilization of water resources and ecological protection in the three northeastern provinces of China (Jilin, Heilongjiang, and Liaoning provinces) from 2012 to 2016 is provided to the scientific management of regional water resources and sustainable development of the economy.[Methods] This study focused on the three provinces in northeast China from 2012 to 2016. The factors examined included water resource conditions, socio-economic developmental level, ecological environment and three aspects of related data, selection of per capita water resources, utilization factor of water resources, modulus of water supply, GDP per capita and per capita domestic water consumption, 10 000 yuan of water consumption for industrial production, 10 000 yuan of water consumption for agricultural production, farmland irrigation rate, ecological water rate, and forest coverage rate. Using 10 major influencing factors of regional water resource carrying capacity as evaluation factors, a fuzzy comprehensive evaluation model was applied.[Results] The average comprehensive score of the three provinces from 2012 to 2016 was 0.468 6 in Liaoning Province, 0.684 0 in Jilin Province, and 0.550 2 in Heilongjiang Province.[Conclusion] The water resource development of the three provinces in northeast China has a certain scale. Although the water resource supply can meet the development needs of the provinces to a certain extent, there is still a shortage of water resources.

Abstract:[Objective] The overall ecological benefits achieved by the Danjiangkou reservoir area and upstream water and soil conservation project ("Danzhi" project) in the second phase of the five-year project (2011-2015) was quantitatively evaluated, in order to provide a reference for decision-making within China's soil and water conservation project and ecological benefit evaluation.[Methods] Based on the grey relational theory, this paper uses a combination of the entropy method and analytic hierarchy process (AHP) to determine the weight of the evaluation index. Based on this, an improved TOPSIS evaluation model was constructed, and the rationality of the results was verified by using "the soil erosion area" index in the project area.[Results] At the beginning of the "Danzhi" project, the various measures had not been perfected, the functions had been relatively lagging behind, and the ecological benefits were relatively low. With the gradual exertion of various functional measures, the ecological benefits of the soil and water conservation had been greatly improved, and the overall ecological benefits at the end of the fifth year have increased by 3.48 times compared with the initial period.[Conclusions] The overall ecological environment in the area of the "Danzhi" project is gradually developing in a benign way, which is consistent with the actual situation in the project area. Based on the improved TOPSIS evaluation model, it has strong applicability and reliability for the benefit evaluation of soil and water conservation project.

Abstract:[Objective] This study aims to explore the regional water stress state and their causes and provides a theoretical basis for the development and allocation of rational water resources.[Methods] A three-dimensional water footprint model was built to analyze the sustainability of water resources by using the sustainability index of water resource. The logarithmic mean divisia index (LMDI) factor decomposition model was also applied to quantitatively analyze the structural, technological, economic, and population effects on water resources in Anhui Province from 2007 to 2016.[Results] ① From 2007 to 2016, the water footprint of Anhui Province, in which the internal water footprints accounted for 97.88% to 98.73%, at first increased and then decreased. The consumption of water by agriculture among the internal water footprints was the highest and showed the same variation as the overall water footprint. In 2016, the per capita agricultural water use in Anhui Province decreased from north to south, meanwhile, the Yangtze River basin accounted for the highest proportion in the other types of water footprint. ② During 2007-2016, the footprint depth of the Anhui Province fluctuated within 2~4 and eventually declined from north to south. The results indicated that the overall sustainable use of water resources in Anhui Province increased from 2007 to 2016. ③ The driving factors of the water footprint in Anhui Province showed that the technical effect was a reverse driving, and the economic effect contributed the most to the positive driving.[Conclusion] The three-dimensional water footprint model used in this study can be a helpful tool to better reflect the actual situation of the water footprint in Anhui Province. Although of the use of water resources generally increased, optimizing the structure of the water resources utilization and accelerating improvements in the efficiency of water resource usage is necessary to alleviate the pressure on water resources resulting from economic development and population growth.

Abstract:[Objective] The susceptibility of regional debris flow was analyzed and an efficient and rapid analysis model proposed for the debris flow disaster prediction research Taonan area of Jilin Province.[Methods] Owing to the current shortcomings of most probabilistic statistical models that have low prediction rates, the random forest algorithm with obvious effect built on an artificial intelligence algorithm was used to study the northwestern mountainous area of Taonan City, Jilin Province. The elevation, slope, aspect, plane curvature, profile curvature, river, normalized difference vegetation index, topographic humidity index, land use, and lithology were selected. A random forest debris flow susceptibility assessment model for the study area was constructed using these factors. The frequency ratio method was used to model and compare with the random forest model. The model effect was verificated using a receiver operating characteristic curve and an area under the curve.[Results] Random forests were used to analyze the sensitivity of debris flow in the study area and were divided into five sensitivity areas by GIS. The disaster points above the high sensitivity area accounted for 82.3%. The success rate and prediction rate of the verification model were 88.4% and 90.4%, respectively, which was better than the success rate and prediction rate of frequency ratio (86.4% and 75.1%).[Conclusion] The sensitivity analysis of debris flow in the Northern Taonan City was performed using the random forest method and compared with the frequency ratio method. The random forest results were reliable and accurate.

Abstract:[Object] The characteristics of the plant growth promoting Bacillus spp. in a feldspathic sandstone soil were investigated in order to provide resources and technical information for feldspathic sandstone soil improvement.[Methods] Bacillus spp. was isolated from plants and feldspathic sandstone soil in a region of Inner Mongolia. The bacterium were identified by 16S rDNA sequence analysis. The ability of Bacillus spp. for producing indole acetic acid (IAA), siderophores, and biofilms were tested. Greenhouse experiments were conducted to evaluate the effect of Bacillus spp. on the quality of feldspathic sandstone soil, and on the growth of alfalfa (Medicogo sativa) and perennial ryegrass (Lolium perenne).[Results] Twelve strains of Bacillus spp. were screened and had different production of IAA, siderophores, and biofilms, which belong to B. halotolerans, B. atrophaeus, B. siamensis and B. zhangzhouensis. The isolated B. halotolerans P75 was able to significantly increase the content of soil organic matter (24.7%), available phosphorus (11.9%), and available potassium (21.0%) in the sandstone compared with the non-inoculated control. Soil invertase activity (58.8%) and the number of culturable bacteria (7.4 lg CFU in 1 g soil) also significantly increased after B. halotolerans P75 inoculation. Moreover, B. halotolerans P75 significantly increased the dry weight of alfalfa and perennial ryegrass grown on the feldspathic sandstone soil by 22.3%~81.5% in comparison to those of the control.[Conclusion] Our results suggest that the B. halotolerans P75, isolated from the alfalfa roots growing in feldspathic sandstone area, can increase the fertility of feldspathic sandstone soil and promote the growth of alfalfa and ryegrass, and has great potential for the phytoremediation and improvement of feldspathic sandstone soil.

Abstract:[Objective] The characteristics of land use change from 2009 to 2017 were analyzed, and the spatial pattern of land use in 2025 of Ningxia eco-economic belt along the Yellow River was simulated in oreder to provide guidance for land development, utilization and protection of the studied area, and to provide reference for the preparation of land space planning.[Methods] Based on the time scale and spatial scale, this study analyzed the changes in land use from 2009 to 2017, calculated the probability matrix for land transfer, and used the CA-Markov model to simulate the land use pattern in 2025 of Ningxia eco-economic belt along the Yellow River based on natural development, land planning, cultivated land and ecological protection scenarios.[Results] All kinds of construction and the cultivated land and other agricultural land exhibited a continuous increase in the Ningxia eco-economic belt along the Yellow River from 2009 to 2017, meanwhile, the garden land, forest land, grassland, water area, natural reservations were reduced. Except for water area and other construction land, the conversion probability of other types of land to urban and rural construction land were generally higher, especially the conversion probability of cultivated land to urban and rural construction land was the highest, reaching 10.65%.[Conclusion] Based on the three scenarios, the land use structure of the Ningxia eco-economic belt along the Yellow River in 2025 is still dominated by grassland, arable land and natural reservations. However, with the acceleration of urbanization and the continuous improvement of infrastructure, the increase in the land used for urban and rural construction, transportation and irrigation works is much more.

Abstract:[Objective] The soil-crop pollution characteristics and changes to the cultivated layer in a lead-zinc mining area of abandonment were analyzed, in order to explore the most reasonable phytoremediation system.[Methods] The distribution pattern and source of heavy-metal pollution in different areas of cultivated land were analyzed using the GIS-based Tominson load index method. The soil-crop pollution characteristics were studied by the enrichment factor method (BCF) and composite quality impact index method (IICQ).[Results] The contents of Cd, Zn, Pb, and Hg in the soil of the cultivated layer in the study area were 100, 45, 18, and 18 times of those of the background values of Guizhou Province, respectively. The levels of Cu, As, and Cr were basically the same as those of the background values. The planting areas of konjac were heavily polluted. The edible parts of stem-type crops had the strongest ability to enrich heavy metals, followed by rice, and the weakest melon crops. The local melon crops can be treated as the first plants to resist heavy metals.[Conclusion] Cd is the main control factor, and the konjac planting area is the main control area. According to the spatial distribution characteristics of heavy metals in the study area, it is recommended to use super-enriched plant restoration. Additional recommendations include the activators working together in heavily polluted areas, to plant anti-enrichment vegetables and block the pollution sources in the moderately polluted areas, and to use passivation measures to achieve the purpose of restoring the heavy metals in the tillage layer soil in the rice-growing areas of the light-polluted areas.

Abstract:[Objective] Some control principles and applicable soil and water conservation measures that should be observed during the ecological construction of a mountain landscape to conserve soil and water were proposed in order to provide reference for soil loss control in the process of mountain landscape construction in the future.[Methods] Taking Dongshan ecological construction project in Baoshan City, Yunnan Province as an example, soil and water loss and its influencing factors of mountain landscape and ecological construction were systematically analyzed.[Results] Aiming at the characteristics of soil erosion caused by mountain project construction, a set of common techniques for soil erosion control from slope surface (such as water interception, terraced land preparation, horizontal terrace preparation and fish scale pit preparation) to the channel for mountain landscape project construction was developed. And the rough calculation of the annual soil erosion amount that can be reduced after the implementation of the soil and water conservation technical measures is more than 5 200 t.[Conclusion] In the process of constructing a mountain landscape ecological project, the principle of protection priority, safety first, and overall consideration should be taken. Considering the economics and ecological characteristics of construction materials, we must also consider the aesthetic factors of the landscape to formulate a complete system of soil and water conservation measures for mountain construction projects.

Abstract:[Objective] This study seeks to assess flood risk to provide reference for regional disaster reduction and socio-economic development in upstream areas of the Ganjiang River.[Methods] The temporal and spatial features data of a rainstorm flood occurring under natural conditions were collected and analyzed. The weights of 14 indicators of 4 factors among risk of disaster-causing factors, sensitivity of disaster-bearing environments, vulnerability of disaster-bearing bodies and the capacity of disaster controls were determined using the analytic hierarchy process (AHP), and then risk factor analysis and comprehensive risk assessment were carried out in GIS.[Results] The floods were mostly concentrated from March to July in the study area. The rainstorms in spring and summer account for 80.4% of the whole year, while the floods accounted for 95.9%. The floods mainly occurred in the northeast. The hazard levels appear higher in the northeast and lower in the west. The sensitivity of the flood inducing environments bands from the northwest to the northeast. The sensitivity in the middle was a little higher than in surrounding areas. The vulnerability levels were higher in the central and western regions but lower in the surrounding areas. The anti-disaster capacity was decreasing from the southwest to the northeast, higher in the west and the south, lower in the east and the north. The comprehensive risk levels were higher in the north central and eastern regions, but lower in the southeast and west. Areas of each risk level was very different in the proportion. The extremely high and high risk accounted for 37.3%.[Conclusion] Floods in the upstream areas of the Ganjiang River are characterized by floods occurring in both the hilly and plain areas. There is a significant positive correlation between rainstorms and floods. These risk assessment results are consistent with the actual situations observed in the study area in most cases, which verifies indirectly the rationality of the indicators selected and the evaluation model.

Abstract:[Objective] Based on the improved unit area ecological service value and land cover data set, the evolution of the ecosystem service value of the Qinghai-Tibet Plateau from 1992 to 2015 was evaluated. Aims included providing spatial guidance for the ecological security of the Qinghai-Tibet Plateau.[Methods] We applied the improved value equivalent factor in combination with CCI-LC long-term sequence land cover data to assess ecosystem service values.[Results] ① The value of the ecosystem services on the Qinghai-Tibet Plateau increased form 1992 to 2015, with an increase of 1.62×10¹¹ yuan in 24 years. The values of services of different ecosystem types were ranked:grassland > water area > forest > farmland > wetland > desert. ② The highest value type was the ecosystem regulation service in 2015, which reached 5.53×10¹² yuan, whereas the values of support service and supply service were 1.33×10¹² yuan and 5.50×10¹¹ yuan, respectively, and the cultural service was of least value at 2.90×10¹¹ yuan. ③ The ecosystem service value was affected by elevation and slope, whereby the highest value was in the range of 4 000~5 000 m elevation and 5°~15° slope.[Conclusion] The total value of the ecosystem services in the Qinghai-Tibet Plateau increased from 1992 to 2015, and the value of different ecosystems and ecosystem service types varied greatly. Terrain conditions affected the value of ecosystem services.

Abstract:[Objective] The changes, influencing factors, and development trends of vegetation cover in Xilinhot City and Abaga Banner, Xilingol League, Inner Mongolia Autonomous Region were analyzed to provide a scientific reference for regional ecological and environmental protection and governance.[Methods] Landsat images in five phases were used to obtain the spatial-temporal evolution of vegetation coverage from 1977 to 2017, which was combined with climate and social-economic data as a means of exploring influencing factors. The CA-Markov model was also used to predict the vegetation coverage in 2025.[Results] ① In terms of time, the vegetation coverage showed a state of decrease from 1977 but then began to slowly increase after 2000. The median and high vegetation coverage area changed in two periods:-27 862.42 km² during 1977-2000 and 16 649.44 km² during 2000-2017. ② Spatially, the vegetation cover in the central part of the study area changed greatly, while that in the northern and eastern regions changed little. In a local ecological nature reserve, the vegetation cover changed little, whereas mining and other production activities caused the decline of surrounding vegetation cover, but urban land use and expansion of accommodation had little impact on the surrounding vegetation cover change. ③ Climate change was the basic driving force, and human factors were the main influencing factor. Ecological construction projects and livestock quantity control had positive effects, whereas livestock quantity overload and mineral exploitation had negative effects. ④ The predicted results for 2025 suggest that vegetation cover will increase and maintain a state of recovery, but that the degree of recovery was not very good.[Conclusion] People in the study area need to focus on the development concept "lucid waters and lush mountains are invaluable assets". An increase in construction efforts for providing ecological and environmental security services is needed to make Inner Mongolia an important ecological security barrier in northern China.

Abstract:[Objective] The temporal and spatial change characteristics and driving factors of land use/cover during 2000-2015 were analyzed to provide a scientific basis for the ecological environment construction and sustainable development of Nanchong City, Sichuan Province.[Methods] Based on Landsat images and QuickBird high-precision remote sensing data in 2000, 2010, and 2015, the direction and amplitude of land use/cover change and land use/cover condition index were calculated.[Results] ① Over the past 15 years, cultivated land and woodland have been the major land use/cover types in Nanchong City, accounting for approximately 80%; however, there were varying degrees of mutual conversion among land use/cover types. ② The area of woodland increased by 1 006.2 km², which was mainly converted from cultivated land and grassland, whereas the area of construction land increased by 965.4 km², which was mostly converted from water and cultivated land. The area of cultivated land, grassland, and waterbody were reduced by 1 549.8, 307.9, and 90.4 km², respectively. ③ Over the past 15 years, the change in the land use/cover condition index showed a good trend for the woodland and construction land (i.e., the condition index change rate of land use/cover was positive), whereas the cultivated land showed a slip trend (i.e., the condition index change rate of land use/cover was negative).[Conclusion] During the past 15 years, the land use/cover in Nanchong City has changed greatly. The major driving factors of land use/cover change in Nanchong City were topography, population, urbanization level, and returning farmland to forestry.

Abstract:[Objective] Spatiotemporal distribution characteristics of the climate change trends during 2015-2100 in the four seasons for the Loess Plateau were studied to provide a scientific basis for formulating adaptive strategies to cope with global climate change.[Methods] Based on the monthly climate datasets of 27 general circulation models (GCMs) from 2015 to 2100, the Delta method was used to process and evaluate the dataset of the Loess Plateau. At the same time, the Mann-Kendall trend test and Sen's slope estimator test were used to analyze the spatiotemporal distribution characteristics of the future climate change trends of this region in all seasons.[Results] ① Among the 27 GCMs used, NorESM1-M and GFDL-ESM2M were the most suitable climate models for simulating the downscaling data of the future monthly mean temperature and precipitation of the Loess Plateau in all seasons. ② There was no significant trend of the mean temperature over the Loess Plateau from 2015 to 2100 in the spring and autumn under the representative concentration pathways(RCP)2.6 scenario, and in the remaining scenarios, the temperature showed a significant upward trend. Precipitation during the four seasons showed a significant upward trend in the spring under the RCP4.5 and RCP8.5 scenarios, while there was no significant trend in the remaining emission scenarios. ③ Under the three kinds of RCP scenarios, the mean temperature of the four seasons increased in the beginning, middle, and end of the 21st century, compared with the climate average; however, the precipitation increased only in spring. ④ Under the three kinds of RCP scenarios, significant differences in the spatial distribution of the mean temperature and precipitation in all seasons were observed.[Conclusion] The climate of the Loess Plateau has a significant response to global warming, and further research is needed on the causes of climate change in the Loess Plateau region in a specific season in the future.

Abstract:[Objective] This study aims to determine the eutrophication status of Shahu Lake, Ningxia Hui Autonomous Region, and to calculate the environmental capacity of the lake for major pollution as a means of providing a basis for reducing the pollution load and improving the environmental protection of Shahu Lake.[Methods] Water samples were collected in January, April, July, and October during 2015-2017 to measure physical and chemical parameters. A comprehensive eutrophic state index was applied to assess the trophic status, and the Vollenweider and Dillon model was used to analyze the environmental capacity of permanganate index(COD_Mn), total nitrogen (TN), and total phosphorus (TP) of the lake under four different water quality target scenarios.[Results] During 2015-2017, Shahu Lake was mildly eutrophic in spring and winter, and moderately eutrophic in summer and autumn. In scenarios two and three of the water quality targets, the remaining environmental capacities for COD_Mn, TN and TP were zero. In scenario four, the remaining environmental capacity of the lake for TN was zero, whereas that for COD_Mn still had a remaining capacity. The environmental capacity of TN had a surplus in 2015, but this was reduced to zero in 2016-2017. On the basis of the water quality in 2017, to attain class Ⅲ water quality requirements, COD_Mn, TN, and TP should be reduced to 655.97, 39.27, and 1.41 tonnes, respectively, which correspond to reduction rates of 112.89%, 45.58%, and 37.60%, respectively. In order to attain class Ⅳ water quality requirements, the COD_Mn, TN and TP should be reduced by 0.0, 15.83, and 0.94 tonnes, respectively, which correspond to reduction rates of 0%, 18.37%, and 25.07%, respectively.[Conclusion] Shahu Lake has certain degree of pollution and has reached a state of eutrophication, the environmental capacities of COD_Mn, TN, and TP in the lake are greater than the target requirement, and should be managed and protected.

Abstract:[Objective] Based on the evaluation of sustainable development of urban agriculture in China and abroad, and considering the multi-function of urban agriculture, an evaluation index system for the sustainable development of urban agriculture was constructed to evaluate the sustainable development of urban agriculture in Changsha-Zhuzhou-Xiangtan urban agglomeration and provide theoretical support for the construction of an urban agglomeration.[Methods] First, the subjective weight of each index was determined using the analytic hierarchy process. Then, using the change of index data, the entropy weight of each index was obtained and the composite weight of each index was determined by subjective weight and entropy weight. Finally, the sustainable development level of urban agriculture in the Changsha-Zhuzhou-Xiangtan urban agglomeration from 2010 to 2017 was evaluated and analyzed based on the TOPSIS model.[Results] ① During 2010-2017, the degree of urban agriculture sustainable development in the Changsha-Zhuzhou-Xiangtan urban agglomeration increased from 0.306 5 to 0.523 9. ② The sustainable development level trend for each sub-function was different, but it was on the rise overall.[Conclusion] The sustainable development level of urban agriculture in the Changsha-Zhuzhou-Xiangtan urban agglomeration fluctuated and increased from "low level" to "medium level". The economic function of urban agriculture gradually weakened and became marginalized. Increasingly more urban agriculture showed its social function, ecological function, and demonstration education function. To promote the sustainable development level of urban agriculture in the Changsha-Zhuzhou-Xiangtan urban agglomeration, it is necessary to maintain a certain amount of data and scale of the urban agricultural landscape land during the construction planning of the urban agglomeration, ensure the integrity of urban agricultural ecosystem structure, and increase the proportion of economic functions and develop each sub-function in a more coordinated way.

Abstract:[Objective] Rocky desertification is an most important environmental problem that restricts the economic and social development of the karst area in Southwest China. The status and characteristics of ecological management of rocky desertification were summarized in order to provide references for formulating a more reasonable strategy for prevention and control of rocky desertification.[Methods] Through reviewing the literature reports and documents and books, the history and developmental stage of rock desertification rehabilitation measures in China were systematically summarized, and individual ecological measures and comprehensive rehabilitation models in use at present were listed.[Results] The measures of stony desertification management in China include 26 types in 7 classes of engineering technologies, 15 types in 4 classed of biotechnologies, 14 types in 3 classes of farming techniques, and other technologies as ecological migration. The types of comprehensive ecological rehabilitation mode include vegetation restoration, ecological agriculture, eco-livestock farming, soil and water conservation, eco-immigration, eco-tourism, integrated management, and others.[Conclusion] The suitability of ecological measures depends on the level of social and economic development and the purpose of management, its suitability varies over time. At present, control of rock desertification in China should begin with releasing population pressure, optimizing land use structure, and maximizing natural self-repair ability.

Abstract:[Objective] This study aimed at ascertaining the water environmental capacity and its changing trends to provide basis for prevention and control of water pollution in Yuehai Lake.[Methods] Water samples were collected in winter (January), spring (April), summer (July) and autumn (October) from 2015 to 2017, respectively. Three water quality control target (WQCT) scenarios were set, and existing models were used to evaluate the permanganate index (COD_Mn), chemical oxygen demand (COD_Cr), biological oxygen demand (BOD₅), total nitrogen (TN), ammonia nitrogen (NH₃-N), and total phosphorus (TP) of Yuehai Lake from 2015 to 2017.[Results] For WQCTs set at level Ⅱ, BOD₅ and NH₃-N have residual environmental capacity, COD_Cr needed to be reduced by 122.4%, 142.7%, and 169.6%, COD_Mn needed to be reduced by 190.7%, 243.8%, and 248.6%, TN needed to be reduced by 47.3%, 40.5%, and 47.1%, and TP needed to be reduced by 67.6%, 71.9%, and 71.0%. If the WQCTs were set at level Ⅲ, BOD₅, NH₃-N, and TN have residual environmental capacity, COD_Cr needed to be reduced by 0%, 4.4%, and 40.3%; COD_Mn needed to be reduced by 7.3%, 85.7%, and 94.1%; and TP needed to be reduced by 35.0%, 42.6%, and 41.8%. If the WQCTs were set at level Ⅳ, all the indicators meet the water quality standard. The surplus environmental capacity showed a trend of decrease over time. The concentration of TP, which was the chief pollutant in the Yuehai Lake, was currently at the level Ⅳ WQCT value.[Conclusion] The water quality of Yuehai Lake from 2015 to 2017 is currently classified as class Ⅳ surface water; certain indicators have a residual environmental capacity based on the WQCT scenarios, and there is a trend of water quality deterioration over time.

Abstract:[Objective] The objective of this study was to provide a theoretical basis for soil erosion control and ecological reconstruction of degraded grasslands, by studying the effects of different vegetation restoration modes on plant community composition, soil moisture content and soil erosion in the degraded desert steppe of Siziwang Banner, Inner Mongolia.[Methods] The characteristics of degraded grassland and soil erosion were used to analyze changes in the plant community, soil moisture, surface runoff and erosion under different vegetation restoration modes. The principal component analysis was used to evaluate the ecological benefits of soil and water conservation based on different vegetation restoration models.[Results] The plant species, total community coverage and aboveground biomass of the three vegetation restoration modes experimental plots in degraded desert steppe were higher than those in grazing natural grassland. The difference in above-ground biomass amounts between the two vegetation restoration modes of "enclosure+ shrub strip + fertilization for rejuvenation" and "enclosure+ loosening soil for re-sowing + grass seed coating" and the grazing natural grassland reached a significant level (p<0.05); The implementation of these three vegetation restoration models effectively controlled soil erosion, making runoff and soil erosion less than that occurring in natural grassland.[Conclusion] The vegetation restoration model of "enclosure+ loosening soil for re-sowing + grass seed coating" has the best ecological benefits for conserving water and soil resources and increasing the stability of communities.

Abstract:[Objective] We studied the dust retention capacity and air purification abilities of different forests (mixed broad-leaved forest, mixed coniferous and broad-leaved forest, mixed cypress forest, mixed coniferous forest and deciduous pine forest) in Chongqing City, which provides scientific basis for the protection and early warning about destruction of forest ecosystems in Chongqing City.[Methods] Spatial and temporal monitoring were carried out on the main forest types, which indicated that the forests providing negative oxygen ions, dust retention, and absorption and transformation of air pollutants in Chongqing City.[Results] The dust retention capacity of these forests was significantly (p<0.05) more than non-forested areas, and the average dust catching quantity was in order of mixed broad-leaved forest > mixed coniferous and broad-leaved forest > mixed cypress forest > mixed coniferous forest > deciduous pine forest. The foliar dust retention of particles in most was total suspended particulate (TSP), while PM₁₀ and PM_2.5 had a certain amount of adsorption. The dust relative content of PM_2.5, PM₁₀ and TSP in mixed broad-leaved forest was the greatest. The dust particle size adsorbed by different green plants ranged from 2.5 to 100 μm, most concentrated under 100 μm (more than 99%). The number of negative oxygen ions and positive oxygen ions produced was highest in the mixed broad-leaved forest > deciduous pine forest > mixed coniferous and broad-leaved forest > mixed coniferous forest > mixed cypress forest, and the value of dust retention, SO₂, HF and NO_x absorption was the greatest in the mixed broad-leaved forest > deciduous pine forest > mixed coniferous and broad-leaved forest > mixed coniferous forest > mixed cypress forest.[Conclusion] The dust pollution in the mixed broad-leaved forest in Chongqing City is serious, but at the same time,the mixed broad-leaved forest had a strong air purification capacity.

Abstract:[Objective] The particle size distribution and fractal characteristics of soil under low-efficiency poplar forests in Ordos region were studied to provide a basis for the cause analysis and transformation of low-efficiency poplar forests in this region, and to provide a reference and decision-making support for the scientific management of poplar plantations.[Methods] We used a Mastersizer 3000 laser diffraction particle size analyzer to measure soil particle size, and a fractal dimension model of soil particle volume to calculate the fractal dimension D, and measured soil nutrients.[Results] ① The main components of soil particles in the low-efficiency poplar forests were fine sand (42.33%), ultra-fine sand (15.72%), and medium sand (19.77%). The main soil texture type was sand and the fractal dimension D of the soil particles was in the range of 1.222 5~2.204 5, which was at a low level. ② The fractal dimension D of soil particles was positively correlated with the silt, ultra-fine sand, and fine sand content, but was negatively correlated with the medium sand, coarse sand, and ultra-coarse sand content. ③ With an increase of the soil layer, the soil particle content with particle size <250 microns increased, whereas the soil particle content with particle size >250 microns decreased. The fractal dimension D value of soil particles increased with an increase of the soil layer; however, the increase was not significant. ④ The relationship among the fractal dimension D of soil particles and the soil organic matter, total nitrogen, available nitrogen, and available phosphorus content was not significant, and the change of soil nutrient content had no significant effect on fractal dimension D.[Conclusion] Sand is the main component of soil particles in low-efficiency poplar forests in the Ordos area. The fractal dimension of the soil is low and the soil structure is very uneven. This type of soil structure is very harmful to the normal growth and development of poplar. This poor soil structure leads to the formation of low-efficiency poplar forests to a certain extent. The soil structure under the forest could be improved by prevention and transformation.

Abstract:[Objective] This study aimed to an investigation into the relationship between the dimensions of the concave cavity and the development of collapsed gullies and collapsed gully erosion in order to provide a scientific basis for the prevention of collapse and the engineering treatment of collapsed gullies.[Methods] The study focused on the collapse mound profile in Tongcheng County in Hubei Province. We calibrated the basic calculation parameters for each soil layer of the collapsed wall, through a series of indoor experiments and actual collapse conditions, introducing the "unit life and death method," which modeled the evolution of the concave cavity, and applied analytical methods to the stability of the caved wall. Initially, 2D finite (FE) numerical models of the collapsed wall-concave cavity were established, based on the ABAQUS software platform, which can be applied to quantitatively analyze the critical splash erosion pit depth value (D₀) required for triggering the collapse of the wall under natural conditions. The sensitivity of the main factors that lead to the failure of the collapsed wall was evaluated by means of the orthogonal experimental design; furthermore, this article selected a series of depths of the concave cavity (less than D₀). This study elucidated the quantitative relation between depths of concave cavity and the saturation threshold value that caused the collapse of the overlying red clay layer.[Results] The safety factor of the collapsed gully wall decreased linearly as the depth of the deep-cut hole increased. The water content of the red clay layer overlying the concave cavity was the most vital factor influencing collapse. In addition, the gradient of the collapsed wall had a significant impact on the stability of the collapsed wall. The relative depth of the concave cavity and the height of collapsed gully wall had little effect on the stability of the collapsed gully wall.[Conclusion] The possibility of collapse of gully walls depends largely on the size of the deep-cut hole and the moisture content of the soil above the concave cavity. Future research should apply this understanding to the prevention of collapse and to the engineering treatment of collapsed gullies.

Abstract:[Objective] We aimed to study and put forward methods for the dynamic monitoring and supervision of regional water erosion based on marked changes in soil erosion factors, this is for improving the mechanism and strengthen the means and strict accountability of their comprehensive supervision, in order to provide effective methods and fine data for formulating precise policies regarding supervision, law enforcement, inspection, supervision, and illegal investigation.[Methods] Based on a comprehensive analysis of the main work progress and existing problems in current soil erosion supervision, using high spatial accuracy and high-potential data, such as high-score remote sensing images, pre-design data of soil and water conservation control projects, and production and construction projects, we took soil erosion plots as units to accurately identify the marked changes in soil erosion factors, interpreted and recognized the marked changes in erosion factors, scientifically calculated the changes in soil erosion intensity and area, and determined the causes of the changes.[Results] The marked changes in erosion factors refer to the local change to a number of soil erosion factors in the region, which presents obvious identifiable and monitorable characteristics. The marked changes are mainly reflected in the changes in land surface gradient, land use type, soil and water conservation measures, vegetation coverage, and so on.[Conclusion] The present technology and methods for the dynamic monitoring of soil erosion based on marked changes in erosion factors are especially suitable for the interannual monitoring of soil erosion and its follow-up supervision and management.

Abstract:[Objective] We aimed to investigate the characteristics of soil erosion in extreme rainfall events to explore the problems related to soil erosion control, and provide the scientific basis for human beings to cope with extreme weather disasters.[Methods] Linqu County, Shandong Province, which was greatly affected by Typhoon Lekima on August 9, 2019, was chosen as the investigation area. By means of data analysis and field investigation, the slope erosion and road erosion characteristics of typical small watersheds in Zengjiagou and Gengjiagou were analyzed, as well as the scouring and silting of various river courses in the upper reaches of the Mihe River.[Results] During the crossing of Typhoon Lekima, the rainfall at the center of the rainstorm reached the 50-year recurrence interval. There was no rill erosion in the forest, grassland and abandoned farmlands, but this did occur in the sloped farmland. The erosion modulus was 4 560~19 500 t/km², and the rills on the terraced fields were concentrated in the position where the catchment above was carried out; the ridges of terraced fields protected by vegetation or stone ridges were intact, while the other types of ridges showed serious collapse. The landslide erosion modulus of the surveyed land was 301~36 321 t/km², and the collapse of ridges was the most serious. The riverbanks, especially at the top of the bend, were severely scoured, and the sediment amount was larger in the river return area, the junction of the two rivers, the barrage, and upstream of the bridge.[Conclusion] Soil and water conservation measures in small watersheds can reduce the soil erosion caused by rainstorms. It is suggested to design and construct suitable water storage and drainage, as well as soil conservation measures for different areas and used land. It may also be helpful to strengthen farmers' agronomic training of soil and water conservation, which could have positive effects on preventing soil erosion disasters caused by heavy rain.