Abstract:Runoff and sediment yield on plot,eroded sediment composition,specific surface area(SSA),and nutrient loss were investigated under field simulated rainfall for two typical shrubs,Caragana korshinkii.and Sophora viciifolia,in the loess gully area.Results showed that both of shrubs can significantly reduce the loss of runoff and sediment.Clay contents,SSA,and nutrient contents decreased with rainfall duration.The organic matter(OM) contents had significant changes with rainfall duration but total phosphorus(TP) contents did not.Clay and nutrient contents in sediment from the two shrub lands were higher than those from the bare lands(CK),and clay and nutrient contents from the Caragana korshinkii lands were higher than those from the Sophora viciifolia lands,which may be resulted from the influence of vegetation including above-ground and below-ground parts.In addition,sediment could enrich clay and nutrients,and the enrichment ratios increased with vegetation coverage but decreased linearly with runoff time.The enrichment ratios of OM in all the plots were greater than 2.5,while the averaged enrichment ratios of TN and TP were 2.13 and 1.23,respectively.The nutrient contents in sediment correlated positively with the content of clay particles(less than 0.002mm) and the SSA,because soil nutrients are mainly carried by fine particles.The SSA can embody the changes of particle size distribution and soil nutrients.

Abstract:Puding County is one of the most serious regions suffering from soil and water loss in Guizhou Province.The area of soil and water loss in the county is 60.8% of the total land area and the soil erosion modulus is 4422.3t/(km²·a).The development of karst fissure,sinkhole,and underground river is found to be the main factor of soil and water loss through analyzing the field data,topographic characteristics,lithologic features,and hydrological condition.The models of soil and water loss and karst leakage are generalized and the relationships among raindrop splash,slope erosion,sinkhole leakage,and underground river transport in the processes of soil and water loss are studied.The mechanisms of soil and water loss in karst area are analyzed as well.The study has a certain signification to prevent soil and water loss in this area.

Abstract:The research area is a typical karst catchment subject to rocky desertification in Huajiang Gorge,Guizhou Province.One representative soil sample was collected in each plot of strong,medium,slight,or latent desertification grade.The research focused on active soil organic carbon(ASOC) in the processes of rocky desertification.Results elucidated that the characteristics such as soil microbial biomass carbon(SMBC),light fraction organic carbon(LFOC),mineralizable carbon(MC),and microbial quotient(qSMBC) had a decreasing trend,while microbial metabolic quotient(qCO₂) had an increasing trend,which acted in accord with the direction of rocky desertification.The above biological characteristics could embody the essence of soil degradation in the processes of rocky desertification.The turn over speed of active SOC in reclamation sequence was higher than that in wood chopping sequence,while the decreased speed of SMBC in reclamation sequence was faster than that in wood chopping sequence.With the long period of accumulation,the wood chopping sequence kept higher SOC content than the reclamation sequence even with high amount of biological return.The biological characteristics such as SMBC,LFOC,MC,labile organic carbon(LOC),qSMBC,and qCO₂ were influenced both by anthropogenic disturbing ways and by the vegetation productivity and could embody the development direction of soil quality.Meanwhile,they were sensitive indexes of estimating soil quality degradation and restoration in the processes of karst rocky desertification.

Abstract:Taking the hilly area of the Loess Plateau to sandy beach as example,this paper analyzes the spatial diversification of soil moisture content in the arid and semi-arid regions using methods of laboratory analysis,and discusses the ways to ecological construction in the area.The study shows that :(1) The soil moisture is increasing alone with north to south orientation,and the main cause is the precipitation character.The drier of soil moisture in the area is,the more instability of soil moisture is.(2) With different types of vegetation,grassland soil moisture is higher,and increases with the depth.Woodland soil moisture is lower,and decreases with the depth,developing dry soil layers extensively.The degree of variability of grassland soil moisture lower than woodland soil moisture,and the soil moisture are more stable.(3) Yulin samples are at environmental conditions of an ancient lake,the soil moisture content is higher than that in semi-arid regions.In the process of ecological restoration of arid and semi-arid areas,it is not desirable to forest in large area,and the right way should be ecosystem-based grass-building,in some special geological conditions such as ancient lake,we can make forestations partly.

Abstract:The eco-hydrological effects of north subtropical secondary bamboo forests(Phyllostachys edulis) were observed and studied in the forest ecosystem station of the Yangtze River delta.Results showed that(1) the ranges of canopy interception,stemfall,and throughfall were 0.21-4.55,0-105.88,and 0-2.8mm,respectively;the ranges of canopy interception ratio,stemfall ratio,and throughfall ratio was 1.3%-100%,0-96.3%,and 0-11.8%,respectively;annual canopy interception,annual stemfall,and annual throughfall were 171.7,864.78,and 74.3mm,respectively;annual canopy interception ratio,annual stemfall ratio,and annual throughfall ratio were 15.5%,77.9%,and 6.7%,respectively.(2) The canopy interception(ratio),stemfall(ratio),and throughfall(ratio) all had correlation with rainfall amount and rainfall intensity to different degrees and rainfall characteristics had the greatest influence on each link of rainfall redistribution.(3) The differences among rainfall redistribution effects of bamboo forest were significant in the different levels of rainfall amount and rainfall intensity.

Abstract:Agricultural activities in riparian directly influence fluvial hydrology and ecology.Since the Yellow River was dammed up by the Xiaolangdi hydro-junction in 1997,72% of the 1 955hm² riparian wetlands have been appearing perennially in Kouma floodplain of Mengjin County,which offers the primary motivation for local agricultural development.The land use type changed remarkably in the past 10 years.28.8% of riparian wetlands changed into the created wetlands,for example,fish ponds or lotus fields and 39.8% of riparian wetlands changed into dryland farms for wheat or cotton cultivation.328hm² remained natural wetlands have been degrading and shrinking severely because of agricultural activities.Based on the field experiments,the characteristics of nutrient loss by runoff in Mengjin riparian dryland farming are analyzed.Results show that rainfall erosivity(R) is an important factor to the amounts of runoff and nutrient loss.Under the condition of low rainfall erosivity,runoff is generated from overflow mostly and however,under the condition of R>19.00,runoff is generated from over-infiltration mostly.There are conic relationships between nutrient loss and rainfall erosivity.Under the condition of moderate rainfall intensity(R=10.0-45.0),nutrient loss may be severe due to the characteristics of infiltration in Kouma floodplain.So,soil and water conservation in riparian should be strengthened imperatively.

Abstract:Soil properties and the contents of its heavy metals in the 20 and 60 age apple orchards of Luochuan County were studied and its environment quality was evaluated.Results show that all the soil samples collected from the orchards were loamy soil with the maximum content of CaCO₃ being 141.71 g/kg,the average content of organic matter being more than 1.26%,and pH value being 7.95~8.62.The soil basically meets the requirements of green apple production.The contents of soil heavy metals in the orchards were higher than its background values.The maximum average content of As was 14.4mg/kg;Cr,84.4mg/kg;Cu,31.7mg/kg;Pb,24.8mg/kg;Ni,33.1mg/kg,and Zn,144.5mg/kg.However,single-factor indices of all the soil samples were below 1 and synthetic pollution indices of soil heavy metals were below 0.7.Soil environment quality in the orchards of Luochuan County is evaluated to be good,reaching the "clean" level.

Abstract:Discharge recession process is an important component of rainfall-runoff process.Analysis of recession process of overland flow under simulated rainfall on cropland of purple soil has been carried out.Results show that slope gradient and rainfall intensity have notable effects on recession flux and inverse recession duration.Recession flux increased as rain intensities increased,and reduced as slope became steeper.Recession flux and time varied significantly under different surface treatments.Under downslope cultivation,recession duration is the shortest and recession flux is the least.Recession process holds longer time and greater flux is produced on bare land.For contour cultivation,recession process lasts the longest but recession flux is less than that on the bare land.The Manning's roughness coefficient for the cropland of purple soil is then calculated by using Retention Curve method.In terms of the coefficient,the order of the three treatments are bare land(0.028)< downslope cultivation(0.065)< contour cultivation(0.071).

Abstract:Six plots(grass slope,grass-cut slope,plowed grass slope,shrubby slope,shrub-cut slope,and plowed shrubby slope) in the Yan'gou watershed were constructed and infiltration data for thirty simulated rainfall events were analyzed.Results showed that the average infiltration rate on vegetable slope was 1.2 times greater than that on shrub-cut slope and 2.0 times greater than that on plowed slope.For the soil bulk density of 1.27 or 0.99 g/cm3 on grass slope or shrubby slope,the average infiltration rate varied with rainfall intensity as a parabolic function at a slope of 7 degree.When rainfall intensities for grass slope,grass-cut slope,shrubby slope,and shrub-cut slope were 1.62,2.21,2.49,and 1.71mm/mim,the maximum averaged infiltration rates were 1.17,0.97,1.67,and 1.51mm/min,respectively.In contrast,when rainfall intensities for plowed grass slope and plowed shrubby slope were 1.36 and 1.68mm/min,the minimum averaged infiltration rates were 0.379 and 0.382mm/min,respectively.In conclusion,the Horton's model better simulates the infiltration process under the condition of the different land uses.

Abstract:Using Landsat TM remotely sensed images captured in 1987,1994,2000,and 2005 as data source,land use/cover change(LUCC) information of Xuzhou City is obtained by decision-tree classification,urban thermal area distribution and thermal environment change are described by land surface temperature which is retrieved through mon-window arithmetic from thermal infrared bands,and then vegetation coverage change is quantitatively depicted by soil adjusted vegetation index(SAVI).Based on information on land cover,land surface temperature,and vegetation coverage,the relationships among vegetation coverage,urban expansion,and urban thermal environment change are comprehensively analyzed.Results show that using decision-tree algorithm is an effective method to obtain the data on land use and land cover.It is appropriate to use land surface radiance bright temperature for the analysis of urban heat environment change.The factors such as SAVI are significantly correlated with urban heat environment and can be used to quantitatively describe urban expansion and eco-environmental response.Research outcomes can be used for the protection of urban environment and the optimization of urban human settlement.

Abstract:A field experiment was conducted to study the spatiotemporal variation of soil moisture in an oasis cotton field with different tillage modes.Results showed that in 0-120cm soil layer,the maximum soil moisture content was observed for no-tillage with mulching stalk;the medium,for no-tillage with standing stubble;and the minimum,for conventional tillage and tillage with film mulching.Soil moisture contents for no-tillage with mulching stalk and no-tillage with standing stubble were higher than those for conventional tillage and tillage with film mulching in 0-20cm soil layer,being significantly different in 0-5cm soil layer and no difference in 20-120cm soil layer.There was an obvious gradient of soil moisture content in the depths for the three tillage modes.Soil moisture contents for the three tillage modes decreased significantly with time before irrigation.The difference between no-tillage and tillage was greater at the early stage than the later stage.High soil moisture content was observed in tilled field after irrigation.Soil moisture in top soil layer was steady for no-tillage with mulching stalk and tillage with film mulching and remarkably varied for no conventional tillage and no-tillage with standing stubble.

Abstract:A special loess gully type,soft-rock loess gully,is distributed in the border area of Shanxi,Shaanxi,and Inner Mongolia,in which water loss and soil erosion are serious.In the study,soil moisture characteristics in the soft-rock loess gully were measured and analyzed.The main results are as follows:(1) In midsummer(July),the averaged soil moisture content of the various parts of the gully was obviously different.The order of landform units from high to low,in terms of soil moisture content,was the bottom of gully(14.44%),the top of sunny slope(9.29%),the top of shady slope(9.01%),the middle of shady slope(8.25%),and the middle of sunny slope(6.36%).While in late autumn(October),the order was the bottom of gully(9.96%),the top of shady slope(9.81%),the middle of sunny slope(9.48%),the middle of shady slope(9.09%),and the top of sunny slope(8.06%).(2) The averaged soil moisture content of soft-rock appeared no obvious seasonal change,but an obvious seasonal change in the averaged soil moisture content was found in loess materials.(3) Water content of mudstone was significantly higher than sandstone along the profile of soft-rock.Moreover,water storage capacity of soft-rock on gentle slope was greater than steep slope.(4) An obvious phenomenon of dried soil layer appeared in the loess profiles.Under low precipitation in summer and autumn,soil moisture seriously was decreased,which was a negative compensation.So,the thickness of dried soil layers was increased.Therefore,dried soil layer is a natural phenomenon in the soft-rock loess gully area of semiarid region and its growth and declination follow the changes of rainfall.

Abstract:采用固定点动态监测的方法,对黄土丘陵区吴起县合家沟流域阳坡和半阳坡各微地形土壤水分进行了对比研究。结果表明,微地形对土壤含水量具有显著影响,阳坡各微地形土壤水分顺序为:切沟>平缓坡>切沟沟头>陡坡>极陡坡;半阳坡各微地形土壤水分顺序为:平缓坡>浅沟>陡坡>极陡坡。0-20cm土层土壤水分变异系数最大的是切沟,最小的是切沟沟头。最后指出在植被恢复过程中,应根据不同微地形的土壤水分分布特征,结合"适地适树,适林适草"的植被恢复原则,合理配置乔、灌、草的营建模式。

Abstract:The vertical variations of different types of soil moisture in Yan'gou watershed in the hilly and gully area of the Loess Plateau are analyzed.Results show that the variation of soil moisture content in different layers is great under the condition of designed experiment.Soil moisture contents on dam,terrace,and slope are consistent with the seasonal change of rainfall.Soil moisture content of 100-200cm layer in orchard fluctuates significantly with the seasonal change of rainfall.The variation of soil moisture content is different in extent not only under the different land types,but also under the same land type.The variation coefficient of soil moisture content is the biggest at 10cm depth and is gradually reduced with increased soil depth.According to the analysis of the variation coefficient,the vertical distribution of soil moisture content under different land types may be divided into vertiginous layer,active layer,subactive layer,and relatively stable layer.Regression equations of the variation coefficient are also found for the soil layers of different land types.

Abstract:The effects of land use and soil properties on the concentrations of total and available Zn in soils were investigated.The ANOVA analysis showed that land use had a significant effect on the concentrations of total and available Zn in agricultural and industrial areas;the concentration of total Zn in vegetable land,dry land,paddy field,and wood land had significant differences except tea garden and orchard;and the content of available Zn in the 6 agricultural land use types did not show significant differences.Moreover,the relationships between the Zn content and soil properties were respectively constructed for agricultural and industrial land use.Results showed that total nitrogen,organic matter and pH had significant influences on the total Zn content.Available phosphorus,available potassium,and the total Zn content had significant effects on the concentration of available Zn in agricultural area.Soil properties did not have significant influences on both the total and available Zn contents in industrial area,and the available content only had strong correlation with the total content.Risk assessment of available Zn using indicator Kriging demonstrated that most of the study areas were in low risk probability for arable activities,and 5.56% of the study areas and 5.99% of the arable land were in high risk probability(>0.100).

Abstract:According to the engineering characteristics of reinforced embankment on soft soil, the characteristics of stability of reinforced embankment on soft soil at different times are determined and the sensitivity of stability to layers of reinforcement, inner friction angle of stiffing, and module of ground are analyzed fromtw o aspects of safety and potential sliding surface by means of strength reduction method and finite difference method. It is found that the more layer of reinforcement, the greater inner friction angle and module of ground are, and the more stable reinforced embankment on soft soil is. However, when some stage exceeds, the effect is no longer apparent . Results presented in the text will have an important reference value to practical engineering of reinforced embankment on soft soil.

Abstract:Transpiration of Stipa bungeana in Huangfuchuan watershed was measured using isolated weighing method.Synchronous environmental factors such as incident solar radiation,air temperature,relative air humidity,wind speed,and soil temperature at depth of 10cm were recorded continuously using automatic weather station.Leaf transpiration rate and leaf stomatal conductance were also measured using LI-6400.The data were then processed using Excel 2003,Visual C⁺⁺ 6.0,and SPSS 13.0. The individual transpiration model was developed by analyzing the correlation between transpiration and environmental factors along with plant characteristic factors.The model is evaluated to be good based on the performance indices.The mathematical model of daily transpiration for S.bungeana in Huangfuchuan watershed was developed based on the model of hourly transpiration.

Abstract:In view of the fact that flush flood and debris flow disasters occur frequently in the upper stream of Miyun reservoir,the theory of Bayes discriminatory analysis is firstly applied in predicting the natural disasters.System science and debris flow prediction theory are adopted to analyze internal elements and external environmental conditions of the system which influences the occurrence of flush flood and debris flow in the area.Accumulated precipitation of the preceding 15 days and intraday precipitation are introduced as model indexes and a set of prediction models is then established.By checking the model with oneself validation and cross validation,the accuracy for judging is 82.4%,which meets the requirement of Bayes discriminatory analysis that the accuracy of judged model should be more than 80%.Two validation results are consistent with each other and the model is stable.Therefore,the established model is credible and can be put into practical use.The research offers a simple and quick way for predicting flush flood and debris flow in the area and provide a support for the prevention and control of flush flood and debris flow in Miyun County,so as to reduce the loss caused by the two types of disaster.

Abstract:In this paper,a composite model based on regression analysis and time series analysis is constructed to improve forecast accuracy and deal with problems of data deficiencies in mid-to-long-term precipitation forecast.Generally speaking,hydrologic time series may be split into the trend,cyclic,and random components.Under this guideline,firstly,precipitation sequence is split into the three components mentioned above by using regression analysis and time series analysis methods;three submodels are respectively constructed for the three components;the independent random sequence is stabilized to modify traditional model structure;and the three submodels are added by linear superposition to establish a new precipitation forecast model(the 3rd type).Later,the paper gives accuracy assessment indexes.Results show that errors of the modified model are lower in rain spell,i.e.,its accuracy is higher than other two models.So,using historical data,the model can work well in precipitation forecast and get a proper accuracy.It is proved to be a practical model for forecast.

Abstract:The paper focused on the soil profile characteristics and soil physico-chemical properties of different degradation grades in the northwest of Sichuan Province.Results showed that the meadow layer of soil profile became smaller,vegetation coverage was declined,and good pasturage was gradually decreased in variety and quantity with increased steppe degradation grades.The contents of organic matter and humic acid showed a downtrend and meanwhile,FA/HA increased gradually.Among soil nutrient substances,the contents of total nitrogen,available nitrogen,total phosphorus,available phosphorus,and available potassium showed a declined tendency.The content of total potassium showed a slight uptrend,but the change was not obvious.Soil pH value also showed a slight uptrend and the pH value of surface layer was less than the value of subsurface layer.

Abstract:Changes in the contents of aqueous and exchangeable selenium in Fluvo-aquic soil were studied by indoor simulated experiment.Calcium dihydrogen phosphate and sulphur were added to the soil.Experimental results showed that the variation of aqueous selenium content was not significant in the soil with the addition of calcium dihydrogen phosphate and sulphur.The proper addition of calcium dihydrogen phosphate increased exchangeable selenium content,but the addition of sulphur showed a weaker effect.The content of exchangeable selenium in soil increased effectively if 0.12% calcium dihydrogen phosphate was added,or 0.12% calcium dihydrogen phosphate and 0.011% sulphur were added.The results were significant of the utilization of selenium-rich soil resources and the development of selenium-rich food.

Abstract:According to mass balance model and the assumption that before ¹³⁷Cs in plow layer was mixed for a uniform distribution,the surface of cultivated soil would form a surface enrichment layer,a quantitative model was developed to relate the amount of ¹³⁷Cs enrichment from the cultivated soil profile to soil deposition rate.During the construction of the model,the depth of surface enrichment layer,the ¹³⁷Cs depth distribution pattern in enrichment layer,the ¹³⁷Cs decay constant,the ¹³⁷Cs input fraction,the depth of plow layer,and sampling year were considered.Results from the model construction prove that the relationship between the rate of soil deposition and ¹³⁷Cs enrichment is neither linear nor logarithmic.

Abstract:In order to understand the extent of soil salinization in the Luohui Trench Irrigation District,63 soil samples and 71 groundwater samples were collected in situ in 2004.Soil salt content,degree of alkalization,anion and cation content,and chemical composition of groundwater were measured respectively.The present situation of soil salinization and the status of groundwater quality were analyzed.Results show that soil salinization in the irrigation district is considerably serious.Saline soils may be classified as the two categories of saline soil and alkali soil.The main salinity composition is consisted of sulfate of sodium(potassium),calcium,and carbonate.The chemical characteristic of groundwater is in the category of sodium chloride-sodium sulfide,basically.It can be inferred that most of groundwater in the irrigation district has an adverse effect on irrigated crops according to its sodium adsorption ratio and magnesium coefficient calculated and has a threat of further alkalization to soil.Hence,an effective control of soil salinization is an important measure to control groundwater table in the irrigation district.Such factors as the concentrations of soluble salts of different districts and the salt-alkali tolerance of crops should be taken into account as well.It is suggested that the measures of engineering,biology,and chemistry should be combined to get twice the achievement with half the effort.

Abstract:Wuqi County is a major county to implement the grain for forest and grass(GFG) project in China,with the percentage of the GFG area reaching as much as 38.3%.So,how to sufficiently guarantee the amount of grain production and continue practicing the GFG is extensively concerned by people.The study is based on the statistical data of Wuqi County from 1999 to 2005.The GFG project affects the relationship between the volume of grain output and demands.It is believed that the GFG project can keep on performing.On the assumption that all conditions are same in the future years,predicting models of total output,population,unit area output,and grain consumption per capita are constructed by using grey predicting method GM(1,1).Using these models,the suitable area for the GFG project from 2008 to 2012 is calculated,which provides a scientific basis for the development of Wuqi County.

Abstract:In order to compare various landslide control schemes and find an integrated control scheme,an optimization approach is established based on entropy weight.Such factors as geological information,practical condition,engineering economy and environmental influence are incorporated.According to the opinion of experts,a comparison matrix is set up.Entropy of decision-making is used to determine the "ideal point".The order of schemes is determined by calculating the close-degree and the distance between the four schemes and "ideal point".Results show that the second scheme is the best one.Entropy of decision-making is a feasible and quantitative selection method,which ensures the objectivity of calculation process and results.

Abstract:Through the analysis of monitoring data in cotton growing period,change in soil salinity with different irrigation norms in the different conditions of drip irrigation are studied.Results show that the quantity of irrigated water has significant influences on soil salinity.The soil salinity after irrigation is significantly lower than the initial soil salinity and the more water,the more obvious effect of washing salt is.The suppression salt treatment of seven-day irrigating cycle is better than 3.5-day irrigating cycle.Soil salinity is increased with emitter distance.The decreased trend of soil salinity is significant under emitter and the salt accumulation has no change within 50cm from emitter in horizontal direction.Through the quantitative analysis of soil salinity around the main root of cotton,the optimal mode of salt washing is the seven-day irrigation cycle with the 3900-4500m³/hm² of irrigation norm.

Abstract:Landuse may change the original vegetation types and their coverage and micro-topography and thus affects soil erosion processes.Landuse type is an important indicator of soil erosion gradation.In this study,the characteristics of soil erosion under the different types of landuses in Dabie Mountain area from 1995 to 2000 are analyzed by selecting the 2000 landuse plan and the map of soil erosion types of 1995-2000 and using the software technique of ArcGIS.The basic features of regional landuse/land cover changes and the change processes of soil erosion under the different types of landuse change are revealed.Result from the study may provide a basis for soil erosion control projects and technical measures.

Abstract:This study takes advantage of modern information means to study the spatial distribution of the intensive use of cultivated land on a certain level.Modern information means play a very important role in promoting farmland management at regional scale and reducing the gap of the intensive use of farmland.The study takes 64 counties as evaluation units to study and analyze the level of spatial distribution of the intensive use of cultivated land by adopting entropy and aggregative index number method and using GIS and geo-science model.Results show that the intensive landuse level in 64 counties appears 4 grade distributions.The intensive use of cultivated land in southeast is higher than northwest.The global Moran index I is 0.23,indicating that the intensive use level of cultivated land appears an aggregated trend in each county,but the aggregated level is not very high.It is not obvious for the high intensive use level region to diffuse its effects.

Abstract:Regional evaluation of debris-flow danger degree is an important part of environment protection and disaster reduction.Based on immune evolutionary algorithm and by collecting typical and complete samples,the projection pursuit cluster model(PPC) is established and applied to treat the multi-factor evaluation of danger degree of debris flow.Projection pursuit can project high dimensional data to low dimensional space.Through studying the main characteristics in the 1-D space,the key information in original data can be obtained,which can not only eliminate the subjectivity of the weight of each factor,but also reveal its impacts on the evaluation according to its actual mean contribution rate,based on the classification of different regional danger degrees of debris flow.In this way,the key factors can be clearly selected.The study further deepens the quantitative understanding of the evaluation factors determining regional danger degree of debris flow.

Abstract:The effects of four soil amendments (PAM, β-cyclodextrin, Wote super absorbent, and humic acid) on soil water retention capacity of Loessial soil are studied in a soil column experiment. Results show that the effects of the amendments on Loessial soil all conform to the equation for soil water content and soil suction. Under the condition of a single amendment, a value is increased with the amendment concentration in the range of 0.05%-0.4%. After 3 weeks or 2 months, a value also changes with the same amendment concentration in the amendment order of PAM > Wote super absorbent > β-cyclodextrin > humic acid. After 4 months, the order is PAM > Wote super absorbent > β-cyclodextrin > humic acid if concent ration is < 0.2% and the order becomes PAM > Wote super absorbent > humic acid > β-cyclodextrin if concentration is 0.2%- 0.4%.

Abstract:Soil nutrients of shrub sand-fixation forest in the Yulin sandy area were measured in this study.Results showed that shrub sand-fixation forest had a significant effect for soil improvement.Soil organic matter in windbreak and sand-fixation forest was increased obviously in the area and the soil nutrient status was improved considerably.Soil organic matter,total N,available P,and available K were increased by 2.2 to 20.6 times,2 to 22 times,0.7 times,and 41%,respectively.However,the pH of soil did not change significantly and presented an alkalescent condition.The study indicates that soil improvement in sandy land is a very slow process and soil nutrients of Yulin sand land still present a lean soil condition as a whole.

Abstract:The conventional road greenbelt pattern focused on landscape benefits and the roles against damage functions and actually neglected the shade stress to farmland.By the study of the shade stress to the plain farmland area in Beijing City,a formula for calculating the minimum road greenbelt width is found.Four improved greenbelt patterns are proposed,which are of practical significance to solve contradictions between road construction and agricultural production.

Abstract:Experiments were conducted indoor and outdoor to study the technology of artificial cultivation of biological soil crust(BSC).Infiltration rates for the soil with and without biological soil crust were measured and runoff coefficients of biological rainwater harvesting plots were determined.Results showed that after treated reasonably,a continuous BSC with > 90% coverage could be formed under 13%-20% relative air humidity,13%-20% substrate humidity,25℃-35℃,and 2500-12000 lx light intensity in 20-30 days.The cultivated BSC growing on an even,smooth,and soil-compressed slope can form an intact biological rainwater harvesting plot.Infiltration rate for the BSC was reduced by 50% compared to the CK and the rainwater harvesting coefficient of BSC rainwater harvesting plot was up to 60%.Moreover,the technology of the BSC cultivation can be used in the propagation of BSC to avoid the damage to environment caused by the over-collection of natural BSC in the establishment of a biological rainwater catchment.

Abstract:Based on the data obtained from landuse change investigation in Dezhou City from 1996 to 2006,changes of landuse structure were described and spatiotemporal variations of regional landuse were analyzed by using the models of change intensity index,relative change rate,landuse dynamic degree and location entropy.Results showed that the change of cultivated land was not significant;scales of urban construction land,traffic land,and forest land were further increased;scale of unused land was reduced fast;and the difference of landuse structure in each county of Dezhou City was evident.Landuse changes in Dezhou city were driven by natural,economic and social factors.Finally,the causes of landuse structure changes were analyzed and some suggestions were put forward.

Abstract:Taking the Baota district of Yan'an City and seven townships(towns) of Ansai County for example,this paper discussed the evolution of regional agro-ecological economic system and the corresponding changes in its ecological and economic benefits.We recognized the major contents of agro-ecological economy and its main influencing factors,and predicted the per-capita income in the following 5-15 years,and the population,per-capital basic farmland,orchards and sheep in the next 30-40 years in its typical watershed region.By the method of system analysis,the main 20 specific indexes from the indexes system were further recognized,which can be categorized into eco-environment,economic benefit and sustainable development,we worked out to construct the eco-agricultural economic indicators evaluation system that are suitable for the loess hills and gully region.

Abstract:The protection countermeasures for the ecological environment of highway construction project in mountain area are investigated in order to minimize the disadvantageous effects of highways construction on the ecological environment along the line.By taking the Ankang-Hanzhong highway construction project for an example,the effects of each function section in highway construction,such as main work,bridge project,tunnel project,service project,and temporary floor area,on the ecological environment along the line are analyzed,and then the environmental protection countermeasures for the different construction stages,such as designing period,construction period,and operating period,are studied.The environmental protection countermeasures,which are reasonable and feasible in practice,are proposed.A better environmental protection measure system of highways construction project is established.

Abstract:Based on field investigation in the typical areas,the gradation of potential soil erosion danger is carried out by using GIS technology.Compared with the index of soil erosion potential danger(SEPDI) of two different periods in 1990 and 2005,purple soil erosion potential danger in Wanzhou District,Chongqing City is analyzed.Results show that by the guideline with Ministry of Water Resources' classification standards,the potential danger of soil erosion may be divided into three grades.The SEPDI in 1990 year is 2.05 and the SEPDI in 2005 is 2.07,which indicates that the SEPDIs of two different periods do not have a remarkable change.By analyzing soil erosion potential danger in the two periods under such influence factors of soil erosion as land use type,vegetation cover,gradient level,and soil thickness,the spatial distribution of soil erosion potential danger is evaluated.At last,the paper summarizes that the causes of soil erosion are the local geographical features,large scale migration,and irrational measures of soil and water conservation.

Abstract:Based on the images in 1998 and 2005,the variations of quantity,inner structure,type,and spatial distribution feature of Shiyang River basin in seven years were analyzed by using RS and GIS and the driving forces of the land use/cover change(LUCC) were further discussed.Results indicated that during the seven years,the areas of grassland,Gobi,sandy land,woodland,dryland,and saline-alkaline land in Shiyang River basin were decreased and alpine,residential area and irrigable land were increased.The most significant increase is the irrigable land and its increased area is 89485.22hm²,which was mainly converted from woodland,saline-alkaline land,residential area,sandy land,and Gobi.The land use dynamic degrees of artificial woodland,saline-alkaline land,and irrigable land were 4.14%,3.48%,2.23% and 2.56%,respectively.The driving forces of the LUCC in Shiyang River basin were the economic development,the pressure of increasing population,and ecological policies.

Abstract:The important water-supply ecological function area of Yellow River in South Gansu is located along the northeast edge of Qinghai-Tibet Plateau.It has the total area of 3057000hm² and is a sensitive change zone of ecological environment in arid territory.The Maqu wetland,once honored as "the reservoir of the Yellow River",tends to be dry up and its ecological environment becomes very fragile.Based on the present ecological situation and the distribution of natural pasture,an appraisal system of ecological frangibility in the area is established by using the related ecological fragility appraisal method and analyzing the meadow ecological environment.The ecological function area can be classified as a medium or serious fragile region.Finally,the causes of ecological fragility are analyzed.It is expected that the study may provide a reference to ecological environment protection.

Abstract:According to statistics from 1991 to 2005 in Tongwei County,factors which impacts modern agricultural development were analyzed by the principal component analysis.The results can be grouped into three aspects: agricultural modern level,the population quality and quantity and land productivity.At the same time,the grey correlative degree was used to analyze these factors.We brought forward some countermeasures,e.g.,increasing investment in agricultural science and technology,rational utilization of chemical fertilizers,and promoting the level of agricultural modernization;the protection of arable land,increase the sown area of crops and cash crops;strictly controlling population growth,vigorously developping,science and technology,and education,etc.

Abstract:According to ecological environment and apple production situation in Ansai County,the hilly and gully area in the middle part and the secondly forest region in the south of Ansai County are suitable to the production of fine table apple.However,the Baiyushan region in the north Ansai County is not suitable to the production of fine table apple on account of low precipitation and low temperature.1.667×10³hm² table apple orchards should be built in the hilly and gully area in the middle and secondly forest region of Ansai County from 2007 to 2010 every year.The total area of apple orchards in Ansai county may be reached 1.667×10⁴hm² in 2010.

Abstract:Taking Heilongjiang Province for an example and using analysis model and grey forecast model,we analyze and forecast the carrying capacity of livestock-breeding environment.Some conclusions can be drawn as follows: The carrying capacity of livestock-breeding environment in the province is strong,but it has appeared a decreasing tendency.According to the present breeding model and the speed of development,the carrying capacity will be below the security line by 2015,if we do nothing for animal excrement.If we take some measures to change 70 percent of animal excrement into energy,feed and fertilizer,the carrying capacity will be below the security line by 2017.For Heilongjiang Province being a big livestock husbandry province with rich natural resources,we should still pay great attention to animal excrement pollution.

Abstract:The paper introduces the construction status,supporting conditions and main implementation approaches of the National Key Project for Soil and Water Conservation of Shanxi Province.Based on the completed project construction practice,construction benefits,existing problems,and some successful experiences in the project are analyzed.The remarkable achievements of the project implementation show that the project mechanism innovation,organization roles and joint efforts of the departments involved in land management,agriculture,forestry,and others,and policies supporting measures can effectively overcome the problems such as unidentified subject and lagged management during the ecological construction.

Abstract:This study was based on dynamic measurement of deserted land in Chaidamu Basin,Qinghai Province,from 1959 to 2004.Results showed that the area of deserted land in the basin increased from 5800000hm² in 1959 to 10254000hm² in 1994,with an increased percentage of 2.13% per year on average.With the implementation of forest policies,the area of deserted land in the basin descended from 10254000hm² in 1994 to 9495000hm² in 2004,with a yearly-dropping percentage of 0.67%.The trend of desertification is still aggravated in some regions.The main factors for the expansion of deserted land were studied as well.Finally,some prevention countermeasures were proposed on the basis of the above study and analysis.