Abstract:[Objective] To explore the mechanism of seasonal responses of soil environmental factors to in-situ ecological remediation of crude-oil contaminated soil in Eastern Gansu Province of the loess plateau, in order to provide reference for the popularization and application of ecological restoration of soil plant microorganisms.[Methods] A combined remediation experiment using the indigenous crude-oil degradation bacteria agent and the native plant (Calendula officinalis) as materials had been conducted for in-situ ecological remediation of crude-oil contaminated soil for 285 days. The changes and seasonal responses to the in-situ ecological remediation of soil physicochemical property, enzyme activity and microbial-community property were investigated using conventional methods.[Results] (1) Soil TPHs degradation rate in summer (24.62%±3.96%) and fall (29.93%±1.94%) were higher than those in spring (3.82%±0.91%) and winter (9.24%±0.87%) during the process of in-situ ecological remediation. (2) There were obvious interactions between remediation treatment and seasonal variation with regard to soil physicochemical property and enzyme activity (p<0.05). Soil pH value, salt content and organic content were lower and soil nutrient were higher in fall in comparison with that of other seasons (p<0.05), respectively. (3) Evenness index of soil microbial community was less in spring (p<0.05), and its richness index was higher in summer (p<0.05), as well as the Shannon-Wiener index was higher in summer and fall (p<0.05). (4) Nonmetric multidimensional scaling analysis suggested that the seasonal difference of soil TPHs degradation rate was strongly affected by the richness index (r²=0.706 3, p=0.002) and soil available phosphous (r²=0.615 7, p=0.005). (5) Variation partitioning analysis revealed that the most important combined environmental factor to determine the degradation rate of soil TPHs in cold season (spring and winter) was the interaction between soil physicochemical properties and enzyme activity (54%). However, 74% of the soil TPHs variation in warm season was explained by soil physicochemical property, enzyme activity and soil microbial community property.[Conclusion] The low soil TPHs degradation rates in spring and winter were resulted from the low evenness index of soil microbial community and low soil enzymes activity; while richness index and the Shannon-Wiener index of soil microbial community, soil available P and ecological remediation effectiveness all resulted to the high soil TPHs degradation rate in summer and fall.

Abstract:[Objective] To analyze the mechanisms of vegetation degradation and stability maintenance during the process of desertification at the southeastern edge of Mu Us sandy land, and to provide scientific basis for the repairing and controlling of desertification.[Methods] The methods of field investigation, field sampling, indoor assay and statistical analysis were integrated to analyze the change of vegetation characteristics during desertification in the study area.[Results] The results of functional and structural characteristics showed that the vegetation coverage, density, richness and Simpson diversity index reduced; The aboveground biomass increased first and then decreased. The changing regularity of organic matter was not obvious, while the total nitrogen content decreased and C/N increased. Vegetation characteristics changed suddenly in the mild desertification stage which was the key stage for desertification repairing. Furthermore, the quantitative measurement of vegetation stability showed that the stability index decreased in the process of desertification, stable and basically stable in non-desertification stage and potential desertification stage, unstable in other stages.[Conclusion] The vegetation degrades and the stability indexes decrease with desertification deepens. Therefore, maintain the virtuous circle of plant-soil system is the key of vegetation restoration and desertification control.

Abstract:[Objective] The grain-size characteristics of suspended load sediments of the Xiangshui River situated in the western Korqin sandy land were investigated in order to better understand the characteristics of sediments in desert river and erosion sediment regularities, and to provide basic information and examples for the study of the interaction between rivers and sand dunes in the desert area.[Methods] Through field investigation, the suspended water samples of three typical sections in the Xiangshui River situated in the western Korqin sandy land were collected, and then the grain-size characteristics of sediments were studied in laboratory.[Results] (1) At the river section I and section Ⅲ, as laterally the mobile dunes on the concave bank of the curved river channel are eroded, the grain size of the sediments becomes thin, and sorting tends to be poorer. (2) At the section Ⅱ, as laterally the Q₃ fluvio-lacustrine strata of the steep slope is eroded, the effect of bend circulation scouring the concave bank is obvious and the silt grain size becomes coarser and sorting. (3) From the upper reaches to the lower reaches of the river, the grain size of silts in the river is significantly coarser, and the sorting becomes better.[Conclusion] The sources of the river derive mainly from the springs of the southern rocky denuded mountains and hills, and the lateral seepages of mobile dunes and Q₃ sandy fluvio-lacustrine strata along the river valley. With the whole drainage area increases, flow velocity and flow flux are continuously augmenting and rive erosion and sand carrying capacity are enhancing due to the increasing number of mobile dunes along the stream. The sediments of the upper and lower reaches of the river coming from the base of the sand dunes are eroded by the water and the sediments of the middle reaches of the river derived from the Q₃ fluvio-lacustrine strata in the collapse of the concave bank.

Abstract:[Objective] The effects of grain for green project on soil quality was explored in order to provide theoretical bases for revegetation and reconstruction of abandoned farmland in semi-arid loess hilly region.[Methods] Comprehensive evaluation of soil physio-chemical factors sampled in different revegetated farmlands was conducted by AHP method in the demonstration area at Zhongzhuang village of Pengyang County, Ningxia Hui Autonomous Region of loess hilly area.[Results] Soil moisture was the main factor that affected soil environment, its weighted value reached 0.210. Followed by soil total porosity and soil organic matter content, their weighted values reached 0.136 and 0.108, respectively. Meanwhile, soil capillary capacity, soil available nitrogen content and soil urease content had also played very important roles on the soil environment, their weighted values were 0.085, 0.071 and 0.064 respectively.[Conclusion] Through comprehensive evaluation on the environmental impacts in terms of soil chemical properties, physical properties and biological activity, to some degree, woodland, terraces, artificial and natural grassland have been improved regarding to soil environmental quality. Among which, terraced field was observed been improved as the greatest type.

Abstract:[Objective] The effects of land use on humus (humic acid, fulvic acid and humin) and four kinds of important soil enzymes in different yellow soil horizon under soil erosion condition were studied in order to provide some scientific basis for maintaining soil fertility.[Methods] Soil samples were collected in different soil horizon (0-10 cm, 10-20 cm and 20-30 cm) at each sample point by zigzag method. Then, soil samples of each layer were mixed evenly in situ and removing of redundant sample was performed by quartering in three times and the corresponding indicators were determined.[Results] (1) Scrub woodland and garden plot had better effect in maintaining soil fertility. However, cultivated land was extremely susceptible to erosion. Soil fertility was directly related with the content of humin of yellow soil. (2) Soil erosion may also affect humic acid content through the loss of water and nitrogen. Fulvic acid of soil in forest land, garden plot and cultivated land lost more easily. However, the grassland had only impact on maintain soil surface fertility. (3) Tillage had significantly adverse effect for activity of urease, alkaline phosphatase and catalase. Meanwhile, soil erosion also evidently affects soil enzymes through the change of soil pH value. (4) Correlation analysis showed that the content of humus component had close contact with the activities of the four kinds of soil enzymes and influenced each other.[Conclusion] The land use types of yellow soil have significantly different effects on humus and soil enzyme activity under erosion.

Abstract:[Objective] Wind speeds at different slope positions of Haloxylon Ammodendron forest were investigated on the northeast edge of Ulan Buh desert, in order to reveal the variation of windbreak effectiveness of Haloxylon ammodendron with plantation age and spatial pattern.[Methods] Forests of H. ammodendron at 3 a, 5 a and 8 a plantation ages were selected as research objects. The wind speeds at 10 cm, 20 cm, 50 cm, 100 cm, 200 cm heights above ground were measured respectively in the bottom, middle and top of windward slope and bottom of leeward slope for windbreak effectiveness analyzing.[Results] The wind speed near ground surface declined with the increase of plantation ages. Windbreak effectiveness of 3 years' shrub was mainly found in 0-100 cm height, the averaged value was 48.19%. At 100-200 cm height, wind speed rebounded to the CK value quickly. Good windbreak effect were found both in 5 years and 8 years forests at height 0-200 cm, and their windbreak efficiency were 69.72% and 71.93% respectively. Correlation analysis showed that there existed a significant correlation between plantation pattern and windbreak effect. The correlation coefficients between windbreak effect and forest coverage, height and crown width were 0.935, 0.930, 0.942 respectively.[Conclusion] Windbreak effects in the bottom of windward slope and leeward slope were better than those in the middle and top of windward slope of 3 years forest. It was contrary for the forests having 5 years and 8 years plantation ages.

Abstract:[Objective] To explore the variations of soil elements and their availabilities in different vegetation successional stages in karst region in order to provide a certain basis for the treatment of rocky desertification.[Methods] Method of investigation in different spatial sites instead of time-series sampling was used. Sites at five different vegetation stages as grass, grass-shrub, shrub, earlier arbor, arbor climax with the same geological backgrounds were investigated and sampled.[Results] The organic matter contents of five vegetation types in shallow soil are all higher than that in deep soil. The elements migration in the vertical direction showed that in shallow soil horizons are all higher than that in deep soil horizons at the early vegetation successional stage and indicate the opposite trend at the late stage. Meanwhile, the elements migration in the horizontal direction indicate the order of earlier arbor stage, climax arbor stage, grass-shrub stage, grass stage, and shrub stage. The soil organic matter showed wavy increase with the vegetation succession and reached the maximum value at climax arbor stage. The availabilities of Mn, Zn, Cu had positive correlations with soil organic matter. Therefore, the soil elements availabilities in shallow soil were higher than that in deep soil.[Conclusion] To deal with the rocky desertification, items of soil thickness, topography and soil element distribution characteristics should be concerned to select reasonable revegetation measures.

Abstract:[Objective] Based on the present popularising plantation of rice under drip irrigation with plastic film mulching, the integrate water and fertilizer technologies in cold region were studied, and an optimized water and fertilize scheme of high yield and high efficiency was put forward in order to provide technical reference and theoretical foundation of matching water and fertilizer management for widespread use of upland rice under drip irrigation with plastic film mulching.[Methods] Using Longjing 31 and Kongyu 131 as materials, the effects of water and fertilizer coupling on yield components and yield of rice under drip irrigation with plastic film mulching in cold region were studied using randomized block experiment design.[Results] Panicles per square meter of the two varieties were both increased in a treatment. Drip-watering volumetric low level of the treatment was 80% of the saturated moisture content, and applied fertilizers at tillering and panicle-growing stages were 87 kg/hm² and 15 kg/hm², respectively. Grain numbers per panicle of the two varieties in all treatments were not significantly different in drip irrigation with plastic mulching. The biomasses, harvest indexes and economic yields of the two varieties were both observed higher in the treatment using 80% of the saturated moisture content as drip-watering volumetric low level than that in the treatment using 60% as the low level. Economic yields of the two varieties were both the lowest in the treatment using 60% of the saturated moisture content as low watering level and simultaneously applying 70 kg/hm² and 12 kg/hm² fertilizers at tillering and panicle-growing stages. For Kongyu 131 variety, the appropriate water and fertilizer coupling pattern in regime of drip irrigation with plastic mulching was as follows:watering low level at 80% of the saturated moisture content, 87 kg/hm² and 15 kg/hm² fertilizers at tillering and panicle-growing stages. For Longjing 31 variety, it was:watering with low level at 80% of the saturated moisture content, 70 kg/hm² and 12 kg/hm² fertilizers at the two stages, respectively.[Conclusion] The responses of the two rice varieties to different treatments of water and fertilizer coupling were different. Water and fertilizer coupling in regime of drip irrigation with plastic film mulching had important effect on the rice yield in cold region.

Abstract:[Objective] To illustrate the comparative effects of salt and alkali stresses on antioxidases of willow, and to provide scientific basis for willow breeding.[Methods] A willow cultivar Salix psammophila (Yanliu yihao) was used in this study. The stress conditions were simulated by five levels of salinities and alkalities with 14 days duration. The salinities were simulated by two neutral salts (NaCl and NaSO₄) and alkalities were simulated by two alkaline salts (NaHCO₃ and Na₂CO₃). The two neutral and alkaline salts were both mixed in the molar ratio of 9:1. The concentrations ranged from 0 to 200 mmol/L both for salt and alkali stress.[Results] Under alkali stress, the activities of superoxide dismutase (SOD), peroxidase(POD) and CAT all presented a tendency of increasing at low concentration stress and then decreasing at high stress. The peak of SOD activity emerged when the willow was treated with 100 mmol/L, which was 1.48 times of the control's; the peak of POD and CAT activities emerged when it was treated with 150 mmol/L, which were 4.26 and 2.79 times of the control's values. Under alkali stress, the activities of SOD,POD and CAT all presented an increasing tendency. The peaks of SOD,POD and CAT activities all emerged at highest contrcentration of 200 mmol/L, they were 1.33,3.26 and 2.29 times of the control's corresponding values. The content of MDA of willow leaf was higher in alkali treatment than that in salt treatment. When the concentrations of neutral and alkaline salts were at 150 mmol/L, the difference of MDA content was biggest.[Conclusion] The alkali stress is different from salt stress, the alkali has stronger injury to willow than the salt stress has.

Abstract:[Objective] Exploring the effects of cattle manure application on soil biological characteristics and growth of poplar plantation, to provide theoretical basis for the establishment of soil fertility system and reasonable fertilization of poplar plantation.[Methods] A field experiment with four treatments, i. e. CK (neither urea nor cattle manure was applied), CF (100% of nitrogen was provided by urea), CM (100% of nitrogen was provided by cattle manure), and CM+CF (50% and 50% of nitrogen was provided by cattle manure and urea, respectively) was conducted to determine effects of different treatments on physicochemical properties, microbial populations, microbial biomass carbon, microbial biomass nitrogen, active organic carbon, carbon pool management index (CPMI) and growth of poplar plantation.[Results] In comparison to CF treatment, CM+CF treatment significantly increased the populations of bacteria, fungi and total microorganism, and the contents of microbial biomass carbon and microbial biomass nitrogen increase 42.20% and 43.75%, respectively. The contents of available nitrogen, available phosphate, available potassium and exchangeable Mg were significantly increased by CM+CF treatment, while the pH value was obviously decreased. Meanwhile, the maximum value of total organic carbon content was observed in CM treatment, whereas the contents of low-labile, moderate-labile and high-labile organic carbon, and CPMI were notably increased by CM+CF treatment, indicative of 52.76, 47.16 and 25.89 increases in CPMI over the values of CK, CF and CM, respectively. Additionally, the average volume growth rate in CM+CF treatment was 45.36%, which was significantly higher than those of other treatments. However, in CM treatment, fewer effects on soil and volume of poplar were observed in comparison with the one of CM+CF treatment.[Conclusion] Cattle manure co-applied with inorganic fertilizer was beneficial to improve soil biological characteristics and promote the growth of poplar plantation.

Abstract:[Objective] In order to select the appropriate biochar for soil improvement and remediation, the physical and chemical properties of biochar produced from chicken manure, the enteromorpha and straw were compared, and the effect of biochar on capacity of soil water holding was also compared.[Methods] The biochars were produced at 350, 500 and 650℃ under anoxic condition. To investigate the impact on soil and properties of biochar produced from three types of biowaste, the elements analysis and pot experiments were performed.[Results] The element contents in three types of material were obviously different. The contents of carbon, hydrogen and ash in straw were higher than those of others. However, it was found that nitrogen content was higher in chicken manure, and carbon content was lower in enteromorpha but oxygen content was higher. Carbon content and nitrogen content of biochar produced from chicken manure were higher than those of the other two feedstocks, and carbon content of enteromorpha was lower. The H/C mole ratio of biochar was obviously lower than that of feedstock, and it decreased with the increase of pyrolysis temperature. However, the C/N mole ratio increased slowly with the increase of pyrolysis temperature. Moreover, it was found that the pH value of biochar produced from different feedstocks increases with pyrolysis temperature. The pH values increased from 6.82~8.35 to 9.33~10.29. Furthermore, the pH values increased as ash content increased. The pH values of biochar increased variously with the increase of ash content, for the three types of biochar, the increase rate ranked:straw > enteromorpha > chicken manure. It was also found that the water holding capacity of biochar produced from three types of feedstocks gradually improved with the increase of pyrolysis temperature.[Conclusion] Biochar produced from chicken manure behaved better than others did in nutrients providing and water holding capacity.

Abstract:[Objective] The influences of different field mulching treatments on soil hydrothermal characteristics and grain yield of spring wheat were studied to provide theoretical basis for the selection of mulching materials and method of soil moisture conservation.[Methods] The experiment had six treatments:traditional flat planting (CK), three levels of wheat straw(straw mulching quantities were 1 500 kg/hm² (SW₁), 3 000 kg/hm² (SW₂), and 4 500 kg/hm² (SW₃)), whole field soil-plastic mulching (FT), and ridges were covered with plastic and the furrows received no mulching (RT).[Results] As compared with CK, RT could advance the seedling emergence, and shorten the growth duration days (103 d). Whereas, SW₃ could delay the emergence, postpone the growth duration (124 d). Treatments of FT and RT could increase soil temperature (0-5 cm) and soil water content (0-100 cm) at the seedling stage. The averaged soil temperature increment was 3.97℃ under RT in comparison with that of CK. Treatments of FT and RT could not increase soil temperature (0-5 cm) and soil water content (0-100 cm) remarkably at stages from jointing to maturity. SW₁,SW₂ and SW₃ decreased soil temperature (0-5 cm) and soil water content (0-100 cm) at the seedling stage, whereas increased soil temperature (0-5 cm) and soil water content (0-100 cm) at stages from jointing to maturity. Soil water content was higher under SW₃ treatment than those of others. Wheat yields under FT and SW₃ treatments were significantly higher than those of other treatments (SW₃, FT > SW₂ > SW₁ > RT > CK). In comparison with the yield of CK, the significant increase under SW₃ was 46.23%, water use efficiency increased by 67.67%, and total water consumption decreased by 18.53%.[Conclusion] Soil moisture and temperature conditions were both improved, wheat yield and water use efficiency were also increased, simultaneously total water consumption was decreased. If the problem of "white pollution" of plastic film mulching is considered, undoubtedly, the wheat straw mulching SW₃(4 500 kg/hm²) is appropriate for its environment-friendship, high-yielding management solution and ecosystem sustainability in dryland agriculture.

Abstract:[Objective] Exploring the effect of different fertilization measures on soil biological characteristics in the farmland of Dezhou City, Shandong Province, in order to provide theoretical basis for the fertilization of farmland and reasonable plantation of crops.[Methods] A field experiment including four treatments, i. e. CK (neither urea nor cattle manure was applied), CF (100% of nitrogen was provided by urea), CM (100% of nitrogen was provided by cattle manure), and CM+CF (50% and 50% of nitrogen was provided by cattle manure and urea, respectively) was performed. The study was conducted to determine the effects of different treatments on soil nutrients, microbial population, microbial diversity index, active organic carbon and carbon pool management index in the farmland of Dezhou City.[Results] CM+CF treatment significantly increased available nitrogen, available phosphorus, available potassium and trace element contents, but decreased the pH value in the farmland soil. The microorganism population and contents of microbial biomass carbon and microbial biomass nitrogen were obviously increased by the use of CM+CF treatment. For bacteria quantity, it increased by 91.22%, 65.47% and 17.11%, respectively, as compared with the treatments of CK, CF and CM. Meanwhile, the microbial diversity index was also found having the highest value in the CM+CF treatment, it had the same variation tendency as total microbial population had. However, the microbial diversity indices and microbial population had different variation tendency between CF and CK treatments. Additionally, the inertly organic carbon content and carbon pool management index in CM+CF treatment were also significantly higher than those of other treatments, indicating carbon pool management index increases by 69.52, 67.84 and 38.61, respectively, as compared with the treatments of CK, CF and CM. However, less effect on farmland soil in CM treatment was observed in comparison with the one in CM+CF treatment.[Conclusion] Cattle manure co-applied with inorganic fertilizer could significantly improve soil biological characteristics in the farmland of Dezhou City, which was beneficial to increase soil fertility and enhance nutrient supplying capability.

Abstract:[Objective] To demonstrate the effects of water-soluble organic carbon in biochar for crop growth and quality and to open up new pathway for the application of biochar.[Methods] Three wheat straw biochar samples at 400℃, 450℃, 500℃ were prepared in laboratory, and corresponding water-soluble organic carbons were extracted with KOH solution to obtain biochar extracts of W₄₀₀, W₄₅₀, W₅₀₀. Furthermore, the extracts were applied in potted garlic test and the effects on garlic growth, quality and soil were measured.[Results] (1) W₄₀₀, W₄₅₀, W₅₀₀ had no significant effects on the growth of garlic. (2) W₄₀₀ treatment increased the content of garlic soluble sugar by 27.53%, increased soil organic matter and available phosphorus by 37%, 26%. (3) Garlic vitamin C, allicin content in the treatment of W₄₅₀ was significantly increased by 34.9% and 8.2%.[Conclusion] Biochar extract has no effect on the growth of garlic, but it can improve the quality of garlic.

Abstract:[Objective] The aim of the study was to provide theoretical basis for the improvement of saline soils by evaluating the improvements in different spacing treatments of blind ditch in the northwest area. Whereby, the salinization prevailed in the widespread area of Northwest China was expected to be restrain and the lands were expected to be use efficiently.[Methods] Saline soil and Two years old Salix babylonica growing on it was used as the experimental materials. The effects of different blind ditch spacing (CK was control,T₁ was 3 m,T₂ was 6 m,T₃ was 9 m,T₄ was 15 m) on soil physical and chemical properties, the growth, leaf spectral photosynthetic characteristics of weeping willow were studied.[Results] (1) Soil water content, pH value and soil salinity of the four treatments were all lower than the corresponding values of the control. The water content of 4 treatments were significantly different from the control (p<0.05) except T₄. The soil salinity of T₃ treatment decreased the most. (2) All the growth indexes of weeping willow were improved in comparison with those of the control treatment. The effect of T₁ ditch spacing treatment is the best and T₄ treatment is the worst. The differences among T₁ and T₂ and T₃ treatments were not significant(p>0.05).(3) Four kinds of ditch spacing treatment significantly increased the leaf photosynthetic rate(P_n), transpiration rate (T_r), stomata conductance (G_s) and chlorophyll content of weeping willows. The differences among T₁ and T₂ and T₃ treatments were not significant (p>0.05). The effect of T₄ spacing treatment is less than the ones of other three treatments.[Conclusion] Therefore, the ditch spacing treatment can effectively discharge salt. When selecting the blind ditch spacing, T₃ ditch spacing treatment is the best solution for its low economic cost.

Abstract:[Objective] To study the relationships between water-consumption characteristics and stem xylem anatomical structures of Zizyphus jujuba and Vitex negundo var. heterophylla, in order to provide technical support for the selection of afforestation species in arid regions of North China.[Methods] The water consumption characteristics of Z. jujubavar and V. negundo. var. heterophylla were studied with the thermal dissipation probe (TDP), and then the xylem anatomical structures of their stem were observed with slicing method.[Results] (1) The water consumption characteristics were different for the two trees in different seasons. In dry season, there were more fluctuating changes both for the two trees as compared with the ones in wet season, and the averages of daily sap flow velocity and daily water consumption were lower. In dry season, the max of sap flow velocity and the average of daily sap flow velocity, and daily water consumption of Z. jujuba were all higher than the ones of V. negundo var. heterophylla. In wet season, these were vice versa. (2) As for xylem anatomical structure of stem, compared with the ones of V. negundo var. heterophylla, the shape and size of Z. jujuba vessel were more uniform. And the average of vessel diameter, vessel length, vessel area and the sapwood relative cross-sectional area of Z. jujuba were all lower than the ones of V. negundo var. heterophylla. Only the vessel density of Z. jujuba var. spinosa was higher than that of V. negundo var. heterophylla. (3) The relative conductivity and the vulnerability indexes of Z. jujuba were lower than the ones of V. negundo var. heterophylla. It showed that the water conduction efficacy of Z. jujuba was lower than that of V. negundo var. heterophylla, and the safety and drought resistance of Z. jujuba were all higher than those of V. negundo var. heterophylla. In wet season, their water-consumption characteristics were mainly determined by the efficacy of water conduction. In dry season, however, their water-consumption characteristics were mainly determined by the safety and drought resistance. These might be the reason that the difference of their water-consumption in different seasons.[Conclusion] Compared with V. negundo var. heterophylla, stem xylem anatomical structure of Z. jujubavar was more capable to transport sap as high as possible, which can made it grow normally. So Z. jujuba was more suitable for the afforestation in arid regions.

Abstract:[Objective] To study the response of seed germination and seedling growth of Lycium ruthenicum to PEG(polyethylene glycol)-simulated drought stress, and to provide a theoretical basis for artificial cultivation of L. ruthenicum.[Methods] PEG-6000 solution was used to simulate drought stress. Seed germination progress, germination percentage, germination potential, germination index, vital index, seedling growth, seedling osmotic adjustment substances, and chlorophyⅡ content under water stress were recorded. The effects of drought stress on seed germination and seedling growth of L. ruthenicum were studied.[Results] Drought stress was disadvantaged to seed germination of L. ruthenicum, and the severe drought stress will delay the fastigium of L. ruthenicum seed germination. Seed germination percentage and germination potential decreased with the increasing level of drought stress. Under -0.6 MPa treatment, germination percentage and germination potential decreased by 72.06% and 74.07% as compared to the one of control treatment. Germination index and vital index were restrained under drought stress, and the restraining degree increased with the increasing of drought stress. The moderate drought stress was beneficial to the growth of radicle and germ, however, it wasn't beneficial to the growth of germ under medium and severe drought stress. Proline and soluble sugar of seedling root and shoot increased with the increasing drought stress level. However, chlorophyⅡ content decreased with the increasing drought stress level.[Conclusion] Drought stress had important effect to the seed germination and seedling growth of L. ruthenicum, and the moderate drought stress was beneficial to the growth of L. ruthenicum seedling.

Abstract:[Objective] Clarifying the relationship between soil humus and Cd in different vegetation was supposed to provide a support for controlling cadmium activity in reclaimed soil.[Methods] The 7-year soil at coal gangue reclamation area in Datong District, Huainan City, was taken as research samples. The contents of humus and cadmium chemical speciation in this region were measured under three typical plant restoration patterns (A Syzygium aromaticum+Robinia pseudoacacia, B Photinia serrulata+Vicia hirsuta, C Ailanthus altissima+V. hirsuta). The chemical morphology of Cd and humus components were determined by tessier five-step extraction method and modified humus analytical method, respectively, and the relationship was illustrated by multivariate statistical analysis.[Results] (1) The humification degree of the C plant allocation pattern was higher than those of A and B in the reclamation area of the mining area; (2) The content of exchangeable Cd in the C plant allocation pattern of the reclaimed land was lower than those in the other two plant allocation patterns; (3) The positive correlation coefficient between available Cd and fulvic acid (FA) was significant in the reclamation area.[Conclusion] Not only can the appropriate plant restoration pattern C adjust the properties and forms of humus in reclaimed soils, but also can affect the potential bioavailability of cadmium.

Abstract:[Objective] To study the influencing factors and rules of loess strength under large strain condition in order to provide a theoretical basis for large deformation damages like landslide in loess area.[Methods] Large shear displacement test with ring shear apparatus were conducted to explore the influence of positive stress and shear modes on the residual strength of remolded loess at different water content levels.[Results] The results showed that the greater the effective normal stress, the greater residual strength was, and the smaller the required shear displacement would be. The residual cohesive force fluctuated slightly and the residual internal friction angle decreased with the increase of water content, and a reference formula between residual internal friction angle and water content was fitted. From the perspective of brittle index, strain softening of the remolded loess was not obvious, and the brittleness index decreased with the increase of effective normal stress and water content.[Conclusion] The responses of the peak strength and residual strength to water content and positive stress were similar. Thus the residual strength can be estimated by water content.

Abstract:[Objective] To explore the physicochemical characteristics of rhizosphere and non-rhizosphere soils under different typical types of vegetation in purple soil hilly region of central Hunan Province, and to provide theoretical basis for ecological restoration.[Methods] The physical and chemical properties of rhizosphere and non-rhizosphere soils from grass(G), grass-shrub(GS), shrub(S) and arbor-shrub(AS) were obtained by sampling and experimental analysis to reveal the coupling relationships with regard to the indexes of physical and chemical properties of between rhizosphere and non-rhizosphere soils.[Results] The contents of fine sand(0.25~0.05 mm) in G and S rhizosphere soils were 76.97% and 63.84% lower that of AS (p<0.05). Whereas, the silt contents were 38.48% and 37.66% higher. The content of 0.25~0.05 mm microaggregate in the AS rhizosphere soil was higher than those of others and the 0.02~0.002 mm microaggregate content of S rhizosphere soil was the highest. The organic matter contents of GS and S in non-rhizosphere soil, were 148.05% and 121.92% (p<0.05) lower than the corresponding ones in rhizosphere soil. Organic matter contents in S and GS rhizosphere soils were 84.28% and 92.08% (p<0.05) higher that of AS. The total nitrogen content in GS rhizosphere soil was 83.33% higher than that in non-rhizosphere soil. The available nitrogen in GS rhizosphere soil was 200.83% higher (p<0.05) than that of AS. Either in rhizosphere soil or in non-rhizosphere soil, phosphorous contents had no significant differences among all types of vegetation. For the same type of vegetation, soil total phosphorous content in rhizosphere soil was lower than that in non-rhizosphere. Soil available phosphorous content in AS was the lowest. In comparison with the ones of G and GS, the available potassium content in AS rhizosphere soil was 125.15% and 137.71% lower(p<0.05). There were closed relationships among the three groups of soil physicochemical indices, referring to the group of soil organic matter and total nutrient content, the group of 2~1 mm, 1~0.5 mm, 0.25~0.05 mm particles and the group of 2~1 mm,1~0.5 mm aggregates.[Conclusion] The coupled relations among soil nutrient, soil particle and soil aggregates should be applied to improve soil physicochemical properties and accelerate the ecosystem restoration in hilly region of central Hunan Province.

Abstract:[Objective] To explore the ecological stoichiometric characteristics of Loropetalum chinense rhizosphere soils and to find out its nutrient use regularity and limiting factors at different vegetation restoration stages of karst region. These works were expected to provide scientific basis for decision making of vegetation restoration and reconstruction in the karst region of Northwest Guangxi Zhuang Autonomous Region.[Methods] Based on the ecological stoichiometry theory, we tested the C:N:P ratios of L. chinense rhizosphere soils sampled at two typical vegetation restoration stages (shrubland and primary forest).[Results] Soil total carbon, nitrogen and phosphorus concentrations of L. chinense rhizosphere soils in shrubland were higher than those of primary forest; while the patterns of C:N, C:P and N:P ratios were on the contrary. The C:P and N:P ratios of L. chinense rhizosphere soils were significantly different among the lower, middle, and upper slopes at the same vegetation restoration stage. In addition, the rhizosphere soil organic carbon was positively correlated with soil N:P ratio (p<0.05); Both of the soil total nitrogen and phosphorus were positively correlated with soil C:N, C:P, N:P ratios (p<0.05); and the soil C:P ratio was positively correlated with C:N and N:P ratios (p<0.05).[Conclusion] The nutrient providing status of L. chinense rhizosphere soil was mainly limited by soil N in the earlier vegetation restoration stage (shrubland), while was mainly limited by soil P in latter vegetation restoration stage (primary forest).

Abstract:[Objective] This paper illustrated the influencing factors of water resource security and its evolution trend aimed to put forward some suggestions about the water resource security in Karst area.[Methods] Based on the data of Guizhou Province in the past ten years, this paper established a BP network model and applied the mean impact value(MIV) algorithm method to analyze the influencing factors of the water resource security in Karst area.[Results] The groundwater supply ratio, the industrial water use proportion, water use efficiency, per capital grain yield and water yield modulus were the obstacles to the development of water resources system. The influencing degree of water yield modulus was decreasing year by year, while the other four factors showed increasing trends. Comprehensive utilization rate of industrial solid waste, the attainment rate of the industrial waste water, the ratio of moderate rocky desertification area, water requirement per-unit GDP and exploitation degree of groundwater were the driving factors. In chronological order, the influence of water requirement of per-unit GDP and exploitation degree of groundwater were stable, while the ratio of moderate rocky desertification area was more and more pronounced. The impact of the attainment rate of the industrial waste water decreased year by year, while comprehensive utilization rate of industrial solid waste fluctuated greatly.[Conclusion] The MIV-BP model is feasible in studying influencing factors of water resource security in karst area.

Abstract:[Objective] To study the water consumption of industrial sectors of the national economy in Guizhou Province and find ways to improve the efficiency of water resources.[Methods] Based on the input-output table of Guizhou Province in 2012, this paper extended the scope of its application to the field of industrial water consumption by means of water resources input-output method, and made a quantitative analysis of the national economic water use in Guizhou Province. The traditional input-output table was combined with the consumption water phase of each department of national economy, and the water resources input-output table and the industrial water use model of Guizhou Province in 2012 was established. The direct water use coefficient, the coefficient of total water use and the coefficient of indirect water use were analyzed.[Results] The second industry department and third industry department were the main water demand departments in Guizhou Province. In addition to agriculture department, other departments also have concealment in water use to some extent. Water use multiplier of each department was high, and the potential improvement for future water use is large.[Conclusion] We should energetically develop modern agriculture and increase the water saving capacity of agriculture, and strengthen the cooperation among all sectors of the second industry, and focus on the development of green recycling industry economy. Follow up the development of "big data" in Guizhou Province and increase the proportion of high-tech industry and service industry.

Abstract:[Objective] To explore the interaction between water use and economic growth in order to provide some scientific basis and decision-making reference for the coordinated development of urban water resource utilization and economic growth in China.[Methods] The article based on decoupling theory, use Tapio elastic analysis to research the relationship between water use and economic growth in China's four municipalities from 2001 to 2014.[Results] (1) Water resource utilization and economic growth overall were in a weak state of decoupling. (2) Agricultural water decoupling was better than that of industry. In terms of agricultural water use, Beijing, Tianjin and Shanghai cities were strongly decoupled; Chongqing City was in weak decoupling state. For industrial water, Beijing and Shanghai City mainly were in strong decoupling, it was contrary for other two cities. (3) Decoupling state of water use and economic growth in Beijing City was best, followed by Shanghai City, Chongqing City was the worst.[Conclusion] Municipal water environment and economy has not yet reached coordinated and sustainable development. Especially, the development of Chongqing City is facing the greatest pressure, followed by Tianjin City. Beijing and Shanghai City should avoid the negative and weak decoupling development.

Abstract:[Objective] The aim of this study was to analyze the characteristics of soil water infiltration in Yaoba Oasis on the west side of Helan Mountains, and to provide theoretical basis for utilizing water resource efficiently and determining a reasonable way for field irrigation.[Methods] The double-ring infiltration experiments from 21 test spots were carried out. The three different infiltration formulas were used to fit the experimental data. And the soil water infiltration characteristics were analyzed using multivariate analysis and geostatistics methods.[Results] The correlation coefficient of fitting results of Horton formula was as high as 0.963, and the relative error and root mean square error were only 4.09% and 0.046 mm/min, respectively, indicating that the fitting accuracy of Horton formula was better than those of Philip formula and Kostiakov formula. Soil texture had a significant impact on infiltration process, great proportion of sand components in the soil had a faster infiltration rate and had relatively shorter time required to achieve stable infiltration. While the soil bulk density and initial water content had a certain influence on cumulative infiltration volume and initial infiltration rate, respectively. The maximum of stable infiltration rate was about 12 times than the minimum one and the coefficient of variation was up to 0.677. The spatial distribution plot showed a decreasing trend of infiltration rate from the northeast to the southwest of the oasis.[Conclusion] Horton formula could be used to describe the process of soil water infiltration in Yaoba Oasis. The difference of soil properties had a great influence on infiltration process, and the infiltration rate presented a strong spatial variability.

Abstract:[Objective] To study the characteristics of soil salinization and the distribution of soil salt ions in Yaoba Oasis of Alax Left Banner in Inner Mongolia Autonomous Region, and to provide a certain basis for the development of agricultural production and ecological environment protection.[Methods] We studied the distribution of soil salinization, the relationship between ion content and values of total alkalinity, salt ion content, as well as the relationship between salt amount and ion content by the means of sampling, GPS positioning and statistical methods. The testing results were analyzed with Excel software and SPSS software.[Results] The average pH value of the irrigation area soil is 8.13, it is alkaline soil. Land of Yaoba Oasis is high in salt content. The salt content of soil is mostly concentrate in 0-10 cm depth, which can reach 4.49%. Cations are mainly Ca²⁺ and K⁺+Na⁺, whereas anions are mainly SO₄^2-, Cl^-, HCO₃^- in the study area, having a rank as:SO₄^2- > Cl^- > HCO₃^-. Content of CO₃^2- accounts for few proportion. There are significant positive correlations between SO₄^2- and Ca²⁺ both in 0-10 cm soil layer and 10-60 cm soil layer, and their correlation coefficients are more than 0.95. Factor analysis showed that there are significant ties between SO₄^2- and Ca²⁺, and between anion Cl^- and cations of K⁺+Na⁺.[Conclusion] The salinized soils in the irrigation area are mainly sulphate and chloride saline soils, which are harmful to the growth of vegetation.

Abstract:[Objective] This study was aimed to provide a basis for decision-making in terms of ecological protection and land use planning in the loess hilly region through exploring the effects of land use pattern on ecological risks.[Methods] Land use pattern model and land use ecological risk index were adopted to quantitatively analyze the land use patterns and ecological risk evolution characteristics.[Results] At the start point of the investigation, the land use pattern model showed a depletion pattern, and the ecological risk was higher in the Shanghuang experimental area. During 1982-2000, the production capacity of the land was improved by carrying out the construction of basic farmlands, strengthening the management of agricultural production, and developing the garden economy. The land use changed from depletion to semi-intensive pattern. Meanwhile, the ecological risk index declined from high-risk to middle-risk class. During 2000-2010, because of the policy conduct of returning farmlands to forests and grasslands, land use further changed from semi-intensive to intensive pattern, and the ecological risk index also reduced from middle-risk to lower-risk class.[Conclusion] Scientific and technological factors are the key that promote the changes of decision-making for land use patterns and ecological risks, whereas the policy factors are the necessary supplements.

Abstract:[Objective] To analyze the types, characteristics, mechanism and main effects of farmers' soil conservation behaviors in the Three Gorges Reservoir area, and to provide a reference for decision-making regarding regional soil erosion control and ecological environment improvement.[Methods] We investigated 113 farmers inhabited in the region with serious soil loss in five counties of the Three Gorges Reservoir area (Chongqing section), using questionnaires and in-depth interviews. According to the survey data, we analyzed the types and mechanism of soil conservation behavior of farmers in the reservoir area.[Results] The farmers' soil conservation behaviors in the Three Gorges Reservoir area mainly include voluntary behaviors and policy-oriented behaviors. Voluntary behaviors are that farmers creatively adapt to the environment and protect farmland, to reduce investment and increase revenue. The farmers' motivation of soil conservation is elicited by farmers' needs. Under the impact of the motivation, farmers are willing to carry out soil conservation practices, including digging side ditches, turning sediments back to farmland, slope length cutdown and downslope tillage, contour ploughing, no-tillage, upslope ploughing, intercropping, planting hedgerow and herbicides weeding. Among them, four kinds of tillage behaviors, i.e., crop intercropping, digging side ditches, slope length cutdown and downslope tillage, and turning sediments back to farmland, are more popular in the Three Gorges reservoir area. Farmers are easily influenced by the national soil conservation policies and thus participate in soil conservation ecological environment construction. The policy-oriented behaviors are a combination of the national strategic needs and the actual needs of farmers, and it could further be categorized into three subtypes. The first one is labor fee. Famers participate in the soil conservation projects such as transforming slope into terrace and obtain remuneration. Secondly, it is economic compensation. Farmers respond to the national demand of soil conservation and take defarming actions and get some compensation. The third category is for government subsidies. Farmers build soil conservation facilities like ponds, roads, etc., for pre or post subsidies.[Conclusion] Farmers in the Three Gorges Reservoir area have rich experience in soil conservation. Many soil conservation behaviors bring positive effects and they are worth promoting among the small watershed management and other ecological construction projects.

Abstract:[Objective] Remote sensing technology was applied to monitor soil and water loss in Fujian Province, in order to provide certain scientific foundation for soil and water conservation in study area.[Methods] The quantitative computation of soil erosion in the study area based on universal soil loss equation (USLE) and remote sensing data of Landsat-8 OLI at 2014 can be inspected with the GIS spatial analysis and mathematical statistic methods to get the space distribution characteristics of soil and water loss in the field.[Results] The total area and rate of soil and water loss in 2014 of Fujian Province were 10 939.8 km² and 8.93%, respectively. Mild erosion played a dominant role and covered 82.3% of the erosive area. Areas having intensive erosion or more intensive level mainly concentrated in Ningde, Nanping, Zhangzhou and Longyan. The erosion area of 22 key soil erosion counties was 4 786.65 km² and the loss rate was 10.54%, accounting for 43.76% of the total erosion area in Fujian Province.[Conclusion] The total 8 954.35 square kilometers erosion area mainly located at altitude of 200~1 000 m and makes up 81.85% of the total erosion area. Slope gradient was found closely associated with soil and water loss, and soil erosion primarily happens in place of 8°~25 ° slope. The loss area on that slope was 69 871.71 km², accounting for 57.23% of the total erosion area. The bare land and forest land are prone to soil erosion, 30.99% and 9.47% of the two lands were in erosion.

Abstract:[Objective] The dynamic variation of net primary productivity of Pinus tabulaeformis forest in Shanxi Province was studied, and the potential for improvement of plantation forest was predicted to provide reference for improving quality of regional forest.[Methods] The regression equation was established using the stratification and harvesting method and the relative growth model. Cumulative method and Thornthwaite Memorial model were used to estimate the actual and potential productivity of the forest.[Results] The productivity of P. tabulaeformis forest increased with the increase of its age and decreased when it evolved into mature period. The actual productivity of P. tabulaeformis forest was 4.462 t/(hm²·a); The contribution of trees was 72.17% to the total productivity at young stand. With the increase of age, total biomass got increase, but in the sense of productivity, it got decrease when evolved into late near-mature period. The contribution of herb layer was 21.16% in the young forest stage, and decreased latterly. On the contrary, the contribution rate of shrub layer increased gradually, which was more than that of the herb layer in the early mature period, when it is critical for structural management. The average potential productivity of forest was 8.422 t/(hm²·a), implied that there was at least 32% potential room for improvement.[Conclusion] The potential room of P. tabulaeformis productivity was at least 32%, and the primary limiting factor of P. tabulaeformis forest productivity in Shanxi Province was rainfall.

Abstract:[Objective] The occurrence condition of geological hazards was analyzed in order to provide a scientific reference for the prevention and control of regional geological hazards in Rongxian County, Guangxi Zhuang Autonomous Region.[Methods] The occurrence and temporal-spatial distribution features were analyzed by adopting a statistical method based on the detailed data of field surveys over the past ten years.[Results] There were 4 types of geological hazard:landslide, collapse, unstable slope and debris flow. Their occurrence scales were small, and occurrence rates accounted for 40.57%, 26.87%, 32.30% and 0.26% of the total hazards respectively. The movement ways were tractive in the landslide, tractive and sliding in the collapse. The unstable slope manifested three types:partial collapse slope, partial erosive slope, and high steep slope. Geological hazards were significantly influenced by local heavy rainfall and typhoon rainfall, and concentrated in the period of June and August, having time lag effect and always happened suddenly in summer rainy season. The geological hazards distributed in the whole region but happened more frequently in some townships. Most of the hazards occurred in low hilly region and granite region, and presented a local linear distribution along the geological structural belt. However, the geological structure had no remarkable impact on these geological hazards.[Conclusion] The occurrence and distribution features are influenced by three aspects, including types of rock soil mass, rainfall and human engineering activity.

Abstract:[Objective] Systematical study the research trends of atmospheric nitrogen deposition in last decade in China, in order to provide reference basis for relevant research.[Methods] The scientific metrology and information technology were used to visualize the patterns and trends of atmospheric nitrogen deposition in last decade in scientific literature by Citespace software.[Results] In the last decade, the effect of nitrogen deposition in forest ecosystem has been focused on the subjects of litter decomposition and soil microbial properties. Researches on the response of grass ecosystem to nitrogen deposition got increase significantly during 2005-2010. Regarding to the research of different ecosystems or sub-ecosystems, grass glade was not attracted as much attention as grassland. In addition, processes of carbon and nitrogen cycles were concentrated on the temperate zone and subtropical zone, and the research content becomes more abundant at present, and the methods are expected to promote the developments of big data analysis and modelling. In respect of the observation of nitrogen deposition flux, most studies referred to aquatic ecosystems. Moreover, nitrogen deposition flux with non-point source pollution got more attention due to the environmental degradation and the development of research methods.[Conclusion] The interdisciplinary and systematicness of atmosphere nitrogen deposition in China were getting enhanced gradually. And the research contents and scale were gradually getting associated and widened. Grass ecosystem, characteristic of microbial community and coupling relationship among nitrogen deposition, global climate change and human activities had attracted more attention in the last decade.

Abstract:[Objective] To provide relevant suggestions for regional ecosystem protection and sustainable development based on topographic gradient via analyzing the spatial distribution of regional ecological system and the variation characteristic of it.[Methods] Topographic gradient index was referred to elevation level, topographic relief and slope variation rate. Distribution index was used to designate topographic gradient distribution and dominant position of cultivated land, waters and wetlands, forestland, grassland, settlement and desert and was analyzed using the data of ecosystem-type-based space distributions in the years of 1993, 2003 and 2013 which was acquired by remote sensing interpretation. Finally, the variations of each ecosystem service item in the years of 1993-2013 were analyzed to provide relevant suggestion for ecological protection.[Results] Cultivated land, waters and wetlands, settlement and grassland mainly distributed on low terrain gradient area; forestland distributed on high terrain gradient area; the distribution characteristic of desert ecosystem was not significantly influenced by gradient. In low terrain gradient area, the values of ecosystem service of cultivated land, waters and wetlands decreased while the values of grassland and settlement showed increasing trends. In high terrain gradient area, the value of ecosystem service of forestland increased as a whole but changed dramatically.[Conclusion] To make plan for regional ecological system of mountain land, the protection for the ecosystem at dominant position should be taken into consideration to prevent it from being replaced by those ecosystem service types having weak ecosystem service function, and to keep it sustainable and healthy in providing ecosystem service.

Abstract:[Objective] To systematically summarize the existing sampling methods, and to explore an optimized sampling strategy to balance the sampling intensity, analysis cost and research precision, which was expected to maximize the accuracy of experiments with minimum economic input.[Methods] On the basis of extensive review on the domestic and foreign literatures in recent years, the optimized sampling strategy for soil properties was summarized. The theory of optimal sampling strategy was elucidated in two parts:the reasonable sampling number and the sampling point layout. Three methods and four modes were introduced to determine the reasonable sampling number and sampling points, respectively, and the future research was prospected.[Results] Most of the sampling program design used in current methods was model-based, and of which the spatial correlation of samples was ignored and relevant information was unused, these all were responsible to the deviation of experimental results and wastes of labor and materials to some extent. In addition, most researches were county scale or and/or lower scale, and there was no unified evaluation system or standards to design a formal sampling program.[Conclusion] In the future, the priority for optimal sampling design should be strengthened.

Abstract:[Objective] To analyze the main characteritics of soil and water conservation (SWC) themes from Chinese newspaper reports, in order to provide a critical basis for understanding public focus, impelling public communication and public participation in China.[Methods] Under the supports of Citespace and NLPIR software, we analyzed the keywords of abstracts and titles of Chinese newspapers (CNKI database) from 20000101 to 20170423 by word frequency statistics.[Results] Reports of SWC increased after 2005, and got steady after 2011. The local newspapers and water industry newspapers contributed 80% of SWC reports. Keywords sprang up in 2000-2003, and among them, the 20% top frequency keywords displayed high frequency than others had, but their centrality in the network of keyword nodes was low. Top frequent keywords of abstracts and titles of 5 newspaper types were similar to each other's.[Conclusion] The SWC newspaper report amount in Chinese language relatively kept in a stable level in recent years, but lacked hot focuses, and showed homogenization. More details are required for the further research.

Abstract:[Objective] The tempo-spatial change characteristics of aerial and subaerial air relative humidity and its responses to temperature and precipitation were explored, to provide basis for the research of climate fluctuation process in Shandong Province.[Methods] Based on the radio sounding and land surface observation data of Shandong Province during 1960-2012, we used regression analysis, IDW, Mann-Kendall non-parametric statistical test and sensitivity analysis to analyze the change characteristics of relative humidity.[Results] The annual subaerial air relative humidity exhibited an obvious decreasing trend (p>0.05) from 1960 to 2012 at a rate of -0.23% per 10 a. In spring, autumn and summer, the values were -0.45%, -0.42% and -0.18% per 10 a, respectively. On the contrary, the relative humidity increased in winter with a rate of 0.10% per 10 a. In spatial, subaerial air relative humidity decreased from the eastern coastal area to the western inland area. However, with regard to the change rate, it is fast in eastern area and slow inland. The aerial air relative humidity had similar spatial change. From the costal to the inland, the decreases in mid and lower troposphere were more obvious than that in the upper troposphere. The seasonal variations could interpret the annual change with different proportions, having an order as:autumn > spring > winter > summer. For mid and lower troposphere, the seasonal contributions ranked as:autumn > winter > spring > summer; For upper troposphere, the rank was summer > autumn > winter > spring.[Conclusion] Sensitivity analysis showed that if drought index changes by 1% during 1960-2012, could induce aerial and subaerial air relative humidity to change by -1.55% and -1.96% respectively; accordingly, if temperature or precipitation changes by 1%, relative humidity will change by -0.15% to 0.09%.

Abstract:[Objective] To analyze the land use and landscape pattern evolution of Hongjiannao region in the past 25 years and to provide basic data and scientific basis for the protection of ecological environment, green mining of Northwest China and environmental management of desert lake.[Methods] Remote sensing images, i. e., TM in 1990, ETM⁺ in 2000, TM in 2005, TM in 2010 and OLI in 2015 were used as data source. Quantitative method of remote sensing and geographic information system technology and mathematical statistical analysis were used to illustrate the land use/land cover dynamic change and landscape pattern evolution characteristics.[Results] From 1990 to 2015, the cultivated land and sandy land area of Hongjiannao region increased by 3.56% and 21.87%; Grassland and water area were reduced by 23.85% and 2.25%, respectively. The water and vegetation shrank greatly, forest and grassland were mainly converted to sandy land and cultivated land. The landscape indexes like average patch area, total number of patch, patch shape index and diversity index all increased; Landscape fragmentation enlarged and landscape types increased.[Conclusion] In the upper reaches of lake, the construction of reservoirs and the exploitation of surface water, the application of returning farmland to forest and grassland, are the main driving influences of landscape pattern changes in Hongjiannao region.

Abstract:[Objective] To Investigate the relief degree of land surface in Hubei Province and illustrate its quantitative correlations with population and economy, in order to provide scientific grounds for the formulation of reasonable policy of population and economy, and the guidance of reasonable distribution of population and economy, as well as the governance of ecological environment.[Methods] The best statistical units for relief degree in Hubei Province were determined using neighborhood analysis, mean change point analysis. The relief degree classification map of Hubei Province was drawn according to the given classification criteria and the influence of relief degree on the distributions of population and economy were analyzed in the investigated region.[Results] The landform generally constituted by plains and hills in Hubei Province. Plains mainly distributed in Jianghan Plain, and the hills mainly distributed in Northern Huanggang, Xianning, Southern Huangshi, Northern Exi and most parts of Southern Exi. These two landforms cover 70% of the total area of Hubei Province. With the increase of the relief degree of land surface, county population density and economic density was both gradually decreased. The smaller the relief degree of counties was, the more vertically scattered of population density and economic density.[Conclusion] There was a negative correlation between the relief degree and population density and economic density, and the relief degree of land surface has strong negative impacts on the distributions of population and economy.

Abstract:[Objective] Temporal and spatial variations of vegetation and its links with temperature and precipitation in Baoji area of Shaanxi Province in the past 13 years during 2001-2013 were studied, in order to provide a strong support for regional agricultural development and ecological civilization construction work.[Methods] Based on the temperature and precipitation in Baoji area from 2001 to 2013, using MODIS NDVI data and 11 meteorological site data, combined with field investigation, univariate linear regression, standardized processing, correlation analysis and other methods were used to analyze the temporal and spatial variation of vegetation cover and its correlations with temperature and precipitation in Baoji area at seasonal scale and reference yearly scale.[Results] Summer vegetation NDVI had an obvious increasing trend, followed by the autumn one, winter vegetation coverage was the worst. The trend of seasonally normalized NDVI in Baoji area was similar to that of temperature and precipitation, the occurrence time of the maximum point was corresponding to that of temperature and precipitation. The correlation coefficients between NDVI and temperature of the four seasons were all higher than that between NDVI and precipitation of the same season (except summer). Correlation coefficient between spring NDVI and winter temperature (-0.592), summer NDVI and spring precipitation (0.640) were all significantly correlated, which implied that spring vegetation cover and previous winter temperature changed consistently in the past 13 years. Summer vegetation cover was coincided with spring precipitation, and NDVI had a lag of 0~3 months behind precipitation.[Conclusion] The average annual and seasonal NDVI in Baoji area showed an increasing trend over all from 2001 to 2013. The vegetation cover change of Baoji area in August was consistent with the change of precipitation, meanwhile precipitation affected vegetation cover stronger than air temperature did in August.

Abstract:[Objective] To monitor the slow/slight change in the loess plateau hilly region in the operation of silt dam and to detect the risk of dam breach in time by 3D laser scanning technology, to provide the bases for scientific monitoring of the silt dam engineering and for safety evaluation in the Middle Gansu loess hilly and gully area, and for silt dams safety in Northwest Loess Plateau as well.[Methods] The settlement, horizontal displacement and surface erosion of Nanwan and Bieduchuan backbone dam were termly scanned by Nove MS 50. The dam and river irregular shape were recorded by equally spaced point cloud and the deformation of silt dam body was analyzed accordingly.[Results] The comparison of two-stage monitoring results showed that there were 1 cm around changes near the road surface in Nanwan backbone dam map, and an obvious change also was found on the left reservoir bank. The change was about 0.8 cm, which might potentially resulted to small-scale collapses. In half year duration, Bieduchuan backbone dam had an about 1~2 cm decline in the right part. Our monitoring results were consistent with the routine monitoring results from the management department.[Conclusion] The accurate, comprehensive, intuitive monitoring data of dam and bank surface obtained timely from 3D laser scanning technology can make the deformation monitoring work more comprehensive, convenient and credible.

Abstract:[Objective] In order to provide the theoretical basis for protecting the ecological environment of Tarim River Basin, the spatial distribution of groundwater level and its effects on vegetation in Aeolian desertification areas was explored.[Methods] MODIS satellite remote sensing image data and combined method of remote sensing-mathematical-model were used. Field investigations of groundwater level, soil moisture, and other relevant information in desertification area in the middle reaches of Tarim River in Xinjiang Uygur Autonomous region were measured. Through the empirical model fitting between the measured soil moisture as independent variable and groundwater level as dependent variable, under the prerequisite condition when there is capillary supply in soil, a simple and effective remote sensing method was proposed, and it was verified that can be used to evaluate the distribution of groundwater level based on the MODIS image data.[Results] The correlation coefficient of the measured groundwater and the remote sensing retrieved water level was 0.896 9, and the error was small. The result proved that the model is applicable.[Conclusion] When groundwater depth is not more than 6 m, it is feasible to use MODIS multi band remote sensing data to monitor and evaluate the groundwater level and its spatial distribution in the desertification area.

Abstract:[Objective] To explore the construction method of sponge city in the principle of ecological water conservancy, in order to solve a series of water security problems, such as the shortage of water resources, frequent floods and deterioration of water ecology.[Methods] The scientific connotation of sponge city and its traditional construction methods were summarized, the limitation of small and medium scale rain management measures was analyzed, the prominent contradiction existing in the construction of sponge city was pointed out, and the feasibility and advantages of ecological water conservancy application in sponge city construction were put forward.[Results] Based on setting mission objectives, basic principles and overall structure, a series of key projects and non-engineering measures were put forward around the construction of ecological water conservancy support system of sponge city.[Conclusion] The application of ecological water conservancy theory to the construction of sponge city is a fundamental way to guarantee urban water security and to solve the urban water problems. The development strategy of ecological water conservancy should be established as the core of the sponge city construction.

Abstract:[Objective] Aiming to solve the problem in construction of foundation engineering in the field of water conservancy, water conservation and civil construction engineering that the steel cage processing platform has the disadvantages of high cost, inconvenient use, large material waste, poor standard and poor processing quality, based on the design idea of "systematization and modularization", a steel cage fabrication platform is designed.[Methods] The machining platform mainly consisted of a fixed support module and a fixed shaft module. The fixed frame module was composed of a pair of fixed supports and the fixed shaft module was composed of a high cage module, a middle cage module and a low cage module. The internal fixing axle module was connected with the external fixing shaft module through the inner rolling bearing. The outer surface of the outer fixed shaft module was provided with a plurality of main rib inserts. The main reinforcement plate was provided with a transverse main reinforcement groove and a longitudinal reinforcing hoop or a supporting hoop slot.[Results] The design could solve the problem that the dimension of reinforcing steel cage of various pile foundations was not universal, and to solve the problems of steel cage processing was not unified, not standard and the steel cage could only be used in a project once. This design could not only make the steel cage more conform to the standard requirements, but also could prevented contamination of the cage caused by soil and oil contamination in the production process. It could greatly improve the production and construction efficiency, and could save costs and protect the environment.[Conclusion] The improvement design of the steel bar cage processing platform is of great importance to the sustainable development of equipment and materials in different types of infrastructure projects. The design can further realize the cyclic application of building materials.

Abstract:[Objective] The experiments about the new materials of HDPE net and plant fiber net were conducted in Hangjin Banner, Duguitala industrial zone of Hobq Desert, in order to provide theoretical support for the sand-barrier optimization.[Methods] The Met One 014 A/024 A 8 channel anemometers (acquisition instrument CR200 X) were used to observe the 1 min-averaged wind speed at the heights of 20 cm, 80 cm, 150 cm and 200 cm, and the wind profiles under the effects of sand-barriers with different materials, specifications, heights of the checkboard barriers and the highly-set vertical sand barriers were comprised and analyzed.[Results] (1) The high parallel sand-barriers, HDPE and plant fiber net sand-barriers with different specifications all could significantly reduce the surface velocity, they also had good sand-fixing benefit. (2) The vertical wind variation range and regularity measured in the center of the checkboard barriers were found strongly related to the sand-barrier plane specification and the exposing height, no relation was found with the materials. Under the same test specification condition, the higher the exposed height was, the much the velocity was reduced. At the checkboards with the same exposure height, the reducing effect of velocity with small size sand-barrier was more obvious. (3) The determination of the sand-fixing effect of sand-barriers with different specifications should take a full consideration of the influences of the topography position, slope direction, slope gradient and surface conditions. Besides that, it also needs to observe the sediment transport intensity, sand-flow field and other factors of the bare land topography that is not within the measurement zone. All these are essential to obtain the effectiveness of the engineering barrier accurately.[Conclusion] The sand barrier of the new material used in the Hobq desert had excellent effects of reducing velocity, and it has great application prospect in the ecological field.

Abstract:[Objective] To find a kind of ecological management technology that can be adopted to solve the ecological problem existed in the Three Gorges reservoir area. Some appropriate ecological management technologies were researched to provide some reference for the restoration of ecological environment in the three gorges reservoir area.[Methods] To improve the foundation stability in the middle and steep soil slope of ecosystem, measure of open circulation of the reinforced concrete frame was adopted. To strengthen the vegetation coverage and soil fertility in the water-level fluctuation zone, measure of contour planted areal greening and geo-cell planted vertical greening were conducted. To increase the biodiversity and landscape level in the water-level fluctuation zone, some suitable plant arrangements at different slope levels in the water-level fluctuation zone were carried out, including "tree-shrub-grass-vine" (177~170 m), "shrub-grass-vine" (170~160 m) and "grass-vine" (160~145 m).[Results] The pattern helped to integrate the traditional concrete slope protection technology and modern ecological slope protection technology, and to integrate contour-planted areal greening and geo-cell planted vertical greening, is beneficial to gain high unity of biological measures and engineering measures, system stability and opening, vegetation coverage rate and landscape level.[Conclusion] The application of this pattern has reference value and application perspective for the ecological management in water level fluctuation zone of the Three Gorges reservoir to some extent.

Abstract:[Objective] Applying low altitude remote sensing to the acceptance of soil and water conservation facilities so as to extract vegetation information based on visible spectrum from remote sensing image, and to propose an accurate and objective method to calculate the coverage rate which is an indicator of the soil and water conservation facilities evaluation in the hope of reducing workload and improving effectiveness.[Methods] The spectral characteristics of low-altitude remote sensing images containing only visible spectral information were analyzed by five vegetation indices as RGRI (ration vegetation index), EXG (excess green),VDVI (visible-band difference vegetation index),NGBDI (normalized green-blue difference index) and NRGRDI (normalized green-red difference index). And the threshold of each vegetation index was determined by the maximum entropy method or bimodal histogram method. Furthermore, with the help of ENVI, the vegetation information was extracted and the vegetation coverage were then calculated and compared with references.[Results] The accuracy of vegetation information extracted from the visible-band difference vegetation index (VDVI) was as high as 95.32%, and the vegetation coverage was 54.43%, which was the closest to the actual value.[Conclusion] It is feasible to calculate vegetation coverage from remote sensing image based on visible band. The method can provide real-time data as supporting information for the acceptance assessment of soil and water conservation facilities with its advantage of few artificial intervention and high accuracy.

Abstract:[Objective] The study was conducted on the selection of organic nutrition-functional soil conditioners and the economic benefit of hybrid feeding sweet sorghum from application of it, in order to solve the bottleneck problem of grey brown desert soil that is characterized by weak water and fertilizer retention, low organic content and the successive low and unsustainable crop yield.[Methods] The ash brown desert soil in Suzhou District, Jiuquan City, Gansu Province was selected as experimental materials and field experiment was conducted.[Results] The amount of organic nutrition-functional soil conditioner was positively correlated with indices of porosity, aggregate, water holding, organic matter, available nitrogen, phosphorus and potassium, economic benefits and yield of hybrid feeding sweet sorghum, while was negatively correlated with soil bulk density and pH value. Soil bulk density and pH value decreased 4.10% and 8.27% as compared with that of conventional fertilizer. Total porosity, capillary porosity, non-capillary porosity, total water holding, capillary porosity water holding capacity and non-capillary porosity water holding capacity increased by 3.63%,3.60%,3.67%,3.63%,3.60% and 3.67%, respectively; organic matter, available nitrogen, phosphorus and potassium increased by 7.03%, 0.37%,0.33% and 0.29%; fungi, bacteria, actinomyces, sucrose, phosphatase and polyphenol oxidase increased by 121.42%, 34.69%, 20.00%, 61.79%, 45.37%, 36.00% and 63.23%, respectively. The grains per spike, grains weight, hundred-grain weight, yield, fertilizer profits and investment efficiency increased by 6.38%, 4.17%, 4.42%, 4.04%, 2 390 yuan/hm² and 0.40 yuan/yuan, respectively.[Conclusion] The grey brown soil physical and chemical properties can be effectively improved by the application of organic nutrition-functional soil conditioners in the Hexi Corridor of Gansu Province, and the water holding capacity, hybrid feeding sweet sorghum yield increased as well.

Abstract:[Objective] To find out suitable soil water conservation measures in arid and degradation mountain regions in North China, in order to provide scientific basis for the development of efficient water-saving forest industry in the northern arid degraded mountainous areas.[Methods] Two years old "Lüling" grafted walnut seedlings were used as materials to study the effects of different combinations of aquasorb, straw and plastic film mulching on soil environment and growth of newly planted young walnut trees. Principal component analysis was used for the comprehensive evaluation of water conservation measures.[Results] Seventeen indices of physical and chemical properties of soil, soil microbial quantity and newly planted tree growth status were used to construct the screening model of water conservation measures on newly planted trees in gneiss mountains. Using the standardized data, four principal components were extracted from 17 indices, which can explain 93.453% of the comprehensive effect of water conservation measures.[Conclusion] The plastic film mulching is the best water conservation measure for newly planted tree in gneiss mountains.

Abstract:[Objective] According to the low water and fertilizer use efficiency in the protected vegetable production, the influences of different fertigation treatments on the dry matter accumulation and nutrient absorption of greenhouse pepper were researched to provide scientific evidence for pepper sustainable production in Gansu Province.[Methods] Field testing was conducted. In which, normal furrow fertilizing was used as control (T₁), fertigation technology (T₂) was carried out to demonstrate its influence on dry matter accumulation and nutrients absorption of Long Pepper No.3 in a solar greenhouse.[Results] (1) Fertigation technology can promote pepper plant's dry matter accumulation significantly, dry matter accumulation increased by 9.21%, dry matter accumulations in fruits and roots increased by 22.47% and 7.29%. The first dry matter equilibrium was advanced by 30 days than normal, while 2nd equilibrium stage was postponed about 41 days. (2) In treatment T₂, the absorption accumulations of N, P₂O₅, K₂O increased by 18.23%, 30.73%, 19.76%, and the N, P₂O₅, K₂O proportion of fruits increased by 9.73%, 13.70%, and 13.00% respectively than the ones of treatment T₁. (3) In comparison with the ones in T₁, the N, P, K use efficiencies of treatment T₂ increased 51%, 43.3%, 71.2% respectively. Furthermore, the treatment T₂ can save 48.9% water, increase 22.1% yield, and increase 3.55×10⁴ yuan/hm² income than treatment T₁.[Conclusion] Fertigation technology can increase the dry matter and nutrients accumulation in pepper, and can increase the allocation proportion of them in fruits.

Abstract:[Objective] The risk of groundwater pollution was evaluated, in order to provide a simple and effective new method for groundwater pollution forecast and risk assessment of both similar construction projects and enterprises' independent environmental impact assessment.[Methods] A solute transport model based on the mathematical model of solute transport was established to predict the pollution levels of COD_Mn and Ni. And a risk assessment method for groundwater protection was developed to evaluate the groundwater contamination risk.[Results] After 100 d of a sudden accident, the maximum migration distance of COD_Mn was 11.6 m, for Ni, it was 10.8 m, having 8.8 m and 8.0 m spreads beyond the boundary of this factory, respectively. The monitor well W₂ was determined as higher pollution risk level, and W₃ as middle pollution risk level.[Conclusion] Pollutants such as COD_Mn and Ni in the groundwater diffuse rapidly, affect water quality seriously, so that track monitoring should be strengthened and the impermeability should be checked regularly.

Abstract:[Objective] The effects of solonchak-improved fertilizer on meadow solonchak and economic benefit of sugar beet was researched by applying it in Hexi corridor of Gansu Province, in order to provide technical support for the sustainable development of beet industry in this area.[Methods] The study was conducted on the meadow solonchak in Huajian Town, Suzhou District, Jiuquan City, Gansu Province through field experiment.[Results] The order of raw materials impacting sugar beet yield were solonchak agent, special fertilizer of sugar beet, organic carbon fertilizer. The formula components of solonchak amendment fertilizer were as following, the special fertilizer of sugar beet was 0.0586, solonchak agent was 0.0623, organic carbon fertilizer was 0.8791. The amount of solonchak-improved fertilizer was positively correlated with indices of porosity, aggregate, water holding, organic matter, available nitrogen, phosphorus and potassium, sugar beet agronomic trait, economic trait and yield; and was negatively related with soil bulk density, pH value and total salt content. Statistical regression showed that the optimum application amount for economic benefit was 39.64 t/hm², at that application level, yield of sugar beet roots would be 96.68 t/hm². The benefits from solonchak-improved fertilizer got 414.48, 946.10 yuan/hm² increases as compared with the benefits from two traditional ameliorants named Kangyanfeng and Wofenglong.[Conclusion] The application of solonchak-improved fertilizer can improve the physical and chemical properties of the meadow solonchaks and increase the soil enzyme activity and the yield of beet.

Abstract:[Objective] The growing coal mining scale and depth easily lead to the occurrence of coalmine water disasters. Consequently, to assure coal mining in a safe and efficient way, mine water discharge is needed to be fully understood.[Methods] According to the physiographic, geological conditions of the researched area and water abundance distribution as well, this paper acquired a full knowledge of the hydrogeological condition of mines. By applying the groundwater flow numerical simulation to the 3₁^# coal seam of the first mine area of the No. 2 coal mine of Nalinhe, this paper established a mine discharge forecast model and its sensitivity was analyzed by enumerating different hydrogeological parameters of the permeability media of all levels. Upon that, the amount of the mine discharge has been forecast.[Results] The groundwater table drop depths will be 32.30 m and 47.72 m respectively, the confined groundwater level drop depths will be 530.37 m and 564.63 m respectively, and the mine water yields will be 57 994 m³/d and 86 240 m³/d respectively at the ends of 5th and 11th year.[Conclusion] If the mine drainage in the first mining area is drained and the drop depth get more and more great, the selection of model parameters will have great influence on the prediction results.

Abstract:[Objective] The relation between landslide hazards and antecedent rainfall in 2008 to 2014 was analyzed. A meteorological early-warning model for the rainfall-induced landslide hazards was established and the weight coefficients of the model were optimized in order to provide an efficient reference for disaster warning.[Methods] Through statistical analysis of the antecedent rainfall based on the precipitation information, we adopted logistic regression analysis to calculate the weights of daily rainfall and optimize the weight coefficients of the model.[Results] The weights of disaster-occurring day rainfall, the 2-day and the 3-day rainfall before landslide disaster are 0.587, 0.220 and 0.189. The weight coefficients of the model for geological background and rainfall are 0.394 and 0.606. The previously occurred disasters were used to test and verify the model and the accuracy is 78.36%. The massively occurred disasters were also taken in July 10, 2013 as a single example to verify the model and the result is rather good.[Conclusion] The model has good early warning effect, so as to provide an efficient reference for the disaster prevention and mitigation.

Abstract:[Objective] To explore the dynamic changes of soil hydrothermal and salt in seasonal freezing and thawing period and its mechanism in order to provide some theoretical basis for soil salinization protection and administer in arid and semi arid areas.[Methods] Horqin meadowland was taken as a research area. Where the hydrothermal and salt observation data of meadow in the Aruga Eco-hydrological Experimental Station of Horqin left-wing post in November 2013-2014, were simulated and analyzed by SHAW model.[Results] The simulated results of soil heat and salt were better, and the root mean square error (RMSE) was 0.02~0.07. Due to the influence of meadow groundwater level, the model has a large deviation from the simulation results of water content, but its standard deviation and mean deviation are within allowable range.[Conclusion] The SHAW model can be used as the optimal model for the simulation of the study. It can compensate for the shortage of artificial observation data intermittent or missing, and can quantitatively predict the migration of hydrothermal salt in the vertical one-dimensional permafrost and free permafrost system under natural conditions.

Abstract:[Objective] Soil particle size composition and soil nutrients of the different forest patterns at arable layer in the Ili River valley were studied to provide scientific basis of cultivation and sustainable management of forest.[Methods] This study analyzed the relationships between soil particle size distribution and soil physicochemical characteristics of different afforestation patterns in the Ili River valley based on fieldwork and laboratory experiments.[Results] The sampled soils of 7 forest patterns were mainly composed of fine silt and coarse silt, and their soil textures were dominated by fine silt-coarse silt-clay, fine silt-coarse silt-very fine sand, and coarse silt-fine silt-very fine sand. Among them, soil nutrients of the fine silt-coarse silt-clay soil were better, and the soil nutrients of the soil with sand were low. Soil organic matter and available nitrogen were closely related to the contents of clay and fine silt, especially to fine silt. Available phosphorus had positive correlations with sand, clay and fine silt content. Available potassium was closely related to the content of clay and fine silt, and the content of available potassium increased with the increase of clay and fine silt content. Available potassium was negatively correlated with sand content; it decreased with the increase of sand content.[Conclusion] The soil nutrient status and the nutrients contents of the 7 forest patterns were different. The soil should be managed according to their nutrient status. The content of silt in soils of different forest patterns had the greatest proportion. According to the correlation analysis between the nutrient content and the particle size, soil fine particle proportion is closely related to soil nutrients.

Abstract:[Objective] To designate key control zones for soil and water loss at or above the county level, and to guide the scientific development of soil and water conservation measures and to improve the effectiveness of soil erosion control.[Methods] On the basis of dividing national and the key prevention regions of soil and water loss in Shaanxi Province, forest coverage, soil erosion intensity and soil erosion control degree were used as quantitative indexes. Headstream, water source and protective zone of basic farmland were used as qualitative indexes.[Results] Using GIS and RS technology, by explaining the remote sensing translation using town as a basic unit, through the combination of qualitative and quantitative methods, the research generated a division graph of key prevention regions of soil and water loss in Shaanxi Province. It was further modified using the qualitative indexes upon the rules of "fragment connected to area, key region outstood, and generalized appropriately. The classification and nomenclature of key prevention regions of soil and water loss focused on geomorphic type, and reference function of soil and water conservation.[Conclusion] This article divided Shaanxi Province into 6 soil and water loss prophylaxis areas and 6 soil and water loss control areas, which could provide a basis for the soil and water conservation planning of Shaanxi Province, being prepared and for standardizing soil and water conservation supervision work in production and construction projects, and also a reference for cities and counties division of soil and water loss prevention and control areas.

Abstract:[Objective] To realize the conservation planning of the high precision and high efficiency and current requirements, and to explore the application of remote sensing technology in foundation and prospects in the planning and design of soil and water conservation.[Methods] The Baojia Temple scenic spot in Hengshan District of Yulin City, Shaanxi Province was chosen to carry out the low altitude remote sensing experiment. Through the establishment of digital elevation model (DEM) and digital orthophoto model (DOM), this paper analyzed comparative advantage between low altitude remote sensing data and other data, and further explored the basic application of low altitude remote sensing in soil and water conservation planning.[Results] By comparison and application analysis, low altitude remote sensing not only has the advantages of good flexibility, good timeliness, high data accuracy and other basic advantages, but also can easily and quickly extract the status quo information and soil and water conservation management information such as basic information of soil and water conservation planning by using other geographic information system software. It can improve work efficiency greatly, and meet the requirements of soil and water conservation planning.[Conclusion] The application of low altitude remote sensing data to soil and water conservation planning has broad prospects.

Abstract:[Objective] This work was to examine several key issues of using the ¹³⁷Cs method to estimate soil erosion rates in order to improve and standardize the method.[Methods] Based on the comprehensive review and synthesis of a large body of published literature and extensive long-term research experience, several key issues in the application of the ¹³⁷Cs method were generalized.[Results] The core assumption that spatial distribution of ¹³⁷Cs inventories is uniform is invalid, and that the ¹³⁷Cs method cannot be used to estimate quantitative soil erosion rates using a single soil core sample. The author emphasized that there existed a random component in ¹³⁷Cs spatial variation, and showed that this spatial random component was the largest uncertainty contributor of the ¹³⁷Cs method using the previous results from a sensitivity and uncertainty analysis.[Conclusion] The erosion estimation error resulting from spatial random variation can be filtered out by using a mean ¹³⁷Cs inventory of multiple independent soil cores or samples. The spatial random component can be removed using appropriate sampling designs for taking independent samples based on geo-statistical properties. Although the ¹³⁷Cs erosion models have been widely used in the literature, none of them has been vigorously tested and validated due to the lack of measured long-term soil loss data, and most models still remain theoretical. Because extremely large differences exist between model estimates, model validation and evaluation are utterly important for successful application and acceptance of the ¹³⁷Cs method.