Abstract:Effects of slope length on detachment and transport processes on a 15° loessial hillslope were quantitatively studied by using simulated rainfall of different intensities.Results showed that runoff discharge increased with an increase in slope gradient.At the 50 and 75 mm/h rainfall intensities,the increment of runoff discharge with an increase in slope length was approximately the same.At the 100 mm/h rainfall intensity,the increment of runoff discharge decreased for the 5 m slope length,but for the 5 m slope length,runoff discharge remarkably increased with an increase in slope length.Sediment yield was fluctuated obviously for the 8 m slope length.Sediment regime was characterized by an alternation of detachment-transport dominated and detachment-deposition dominated.

Abstract:In the karst depression areas of Northwest Guangxi Zhuang Autonomous Region,grid sampling method(2 m×2 m) was adopted in the square area(10 m×10 m) and soil moisture content in 0—80 cm soil profiles at a 10 cm interval with two landuse types was measured in May,2005.The vertical variability construction and distribution pattern were analyzed by the geo-statistics method.Results showed that cropland and grassland had weak variability.Their vertical variability decreased and then increased along with increased soil depth but grassland had greater spatial variability.Both cropland and grassland had good semi-variance structure and strong spatial correlation and could be well expressed by spherical model.The ranges of the two landuse types were 66 and 49.1 cm,respectively.They both had obvious anisotropy in vertical soil layers and could be fit with exponential model.It was also found that the spatial variability of soil moisture in vertical depth had a close relationship with soil physical properties under both landuse types.Conclusions from the research help to maintain soil moisture and promote vegetation restoration in the depression areas after the grain-for-green project.

Abstract:Based on the fractal theory,soil fractal features of five types of vegetation in the Ziwuling forest area were studied on contrast to the 6-year abandoned farmland.Results show that the aggregate fractal dimension,the pore fractal dimension,and the mean weight diameter of aggregates can indicate soil structure stability.The aggregate fractal dimension and pore fractal dimension are highly correlated to the content of 0.25 mm aggregates,the content of soil organic carbon,and soil bulk density.So they can be used as the indexes to evaluate soil structure stability.The mean weight diameter does not have significant correlations with the content of soil organic carbon and soil bulk density and however,it has significantly positive correlations with the content of 0.25 mm aggregate and the content of 5 mm aggregates.The mean weight diameter can only be used as the index to evaluate the content of large soil aggregates.As contrasted to the abandoned farmland,soil structure is improved under other four types of vegetation.

Abstract:The typical severely degraded regions due to irrational utilization of water and land in the lower reaches of Tarim River were chosen as a study area. By using the germination method in the experiment on germination of soil seed bank,the dynamics of basic characteristics,density,and species of soil seed bank were analyzed.Vegetation restoration in the areas was also discussed in terms of potential role of the soil!seed bank.Results show that without taking the effect of graze into account,seasonal dynamics of the soil seed bank is quite obvious and density and species abundance of the seed bank in March is lower than that in August.In terms of species composition,annual herbaceous plant is dominant in March and the seeds of Populus euphratica Oliv and Tamarix L almost appear in August.With the aggravated degradation,density and species abundance of the soil seed bank decrease significantly.To activate the soil seed bank is feasible theoretically for vegetation restoration in the lower reaches of Tarim River,for density and species abundance of soil seed bank is further larger than those of standing vegetation.Taking account of vegetation restoration and regeneration,our study suggests that the best time for water transferring should be from August to November.

Abstract:Response of eco-physiological characteristics to CO₂ in Stipa bungeana,Artemisia sacrorum,Stipa grandis,and Aneurolepidium dasystachys leaves was studied.Results showed that with CO₂ concentration increasing,photosynthesis rate(Pn),intercellular CO₂ concentration,and water use efficiency(WUE) of the four species were increased and stomatal conductance and transpiration rate(Tr) were decreased.Photosynthesis characteristics of the four species varied with season.The order of the species,in terms of Pn and Tr,was: Stipa grandis Artemisia sacrorum Stipa bungeana Aneurolepidium dasystachys;and the order of the species,in terms of WUE,was: Stipa bungeana Artemisia sacrorum Stipa grandis Aneurolepidium dasystachys.Meanwhile,PSⅡ open proportion,conversion efficiency of primary light energy under light of PSⅡ,actual PSⅡ efficiency,and PhiCO₂ were linearly increased with CO₂ concentration.However,the non-photochemical quenching coefficient presented a decline trend.

Abstract:Characteristics of soil profile and vegetation distribution pattern in micro scale(a 32 m long transect) in sodic alkaline soil region were discussed.Results showed that soil distribution patterns along the transect from low land up to upland were sodic saline meadow soil,shallow columnar sodic alkaline soil,white crust sodic alkaline soil,and mid columnar sodic alkaline soil.Vegetation included Ranunculus cymbalaria Pursh /Polygonum aviculare L community,Potentilla anserina L community,Carex duriuscula C.A.Mey/Leymus chinensis Tzvel community,bare land,and Leymus chinensis Tzvel/Puccinellia tenuiflora Scrib.Et Merr./Chloris virgata Swarta community.The Ranunculus cymbalaria Pursh /Polygonum aviculare L community and Carex duriuscula C.A.Mey/Leymus chinensis Tzvel community were distributed around the shallow basin in ring-like pattern;bare land and Leymus chinensis Tzvel/ Puccinellia tenuiflora Scrib.Et Merr./Chloris virgata Swarta community were distributed in patch pattern.Bio-diversity and coverage of vegetation along the margin of shallow basin were maximal and its biomass was highest.Vegetation in micro flat upland was dwarf and with lower biomass.The salinity in bare land could reach as high as 3.38% and soil structure was extremely compacted.Therefore,the production of vegetation was restrained.

Abstract:A research on the growth status of Trifolium repens and it's influences on soil nutrients was performed through measuring its biomass and growth factor,as well as soil organic matter,total N,total P,total K,hydrolytic N,available P,and available K.The land without fertilizer application and with successive cutting within two years was selected,and each time,all Trifolium repens above soil was harvested for the experiment.The research indicates that with the increasing harvesting time,the fresh and dry weight of Trifolium repens,its average length,and its stem diameter were decreased by 14.34%,13.12%,5.20%,and 3.38% per year,respectively.As for the upper layer soil,its organic matter varied from 24.37% to 8.75%.Its total N,total P,and total K were not apparently affected,but its available P,available K,and hydrolytic N were greatly affected,which were decreased by 46.56%,43.63%,and 16.69% in the two years,respectively.As for the bottom soil,changes in organic matter,total N,total P,and total K were like those in the upper layer soil,but its available P was greatly decreased compared with hydrolytic N and available K.Comprehensive analysis demonstrates that increasing harvesting time may lead to the decreases of soil fertility and productivity.Therefore,for a sustainable development,it is necessary to apply a certain amount of compound fertilizer,phosphorus fertilizer,and potassium fertilizer to the soil after successive cutting.

Abstract:Investigation was carried out on the main plant communities in Yanchi sandy land by sampling method and soil water content was measured on each sample plot,as well as the seasonal change of soil water content in the different plant communities.Results show that plant communities on the flat sandy land with impermeable stratum below root layer,in terms of average soil water content in different plots,ranke in the ascendant order of Leymus secalinus community (4.91%),Oxytropis aciphylla community(7.42%),Caragana korshinskii Community(10.36%),Artemisia ordosica Community(12.55%),and bare sandy land(16.27%).In the same plant community,soil water content is different in different seasons.During vegetation construction on sandy land,we should select Caragana korshinskii and Artemisia ordosica as the main artificial vegetation species and control the density of plant in a reasonable range or distribute some proportion of bare sandy land to achieve a long-term stable state.

Abstract:Understory vegetation,one of the important parts of forest ecosystem structure,has some effects on material cycling,biodiversity,succession,and development of forest ecosystem.To study the structure and biomass dynamics of understory vegetation,investigations were conducted on the typical plantations of the mixed alder(Aluns cremastogyne) and cypress(Cupressus funebris) at 10,15,20,25,and 30 year cypress plantation succeeded from the mixed plantations in the hilly areas of central Sichuan basin.Results showed that species abundance in shrub and herb layers increased from 10th to 20th years.However,from 20th to 30th years,species abundance in shrub layer declined significantly,and in herb layer,it did not change significantly.Heights of shrub and herb layers increased significantly from 10th to 15th years and decreased slowly from 15th to 30th years.Spatial heterogeneity of shrub height in the samples at the same age was higher.Coverage degrees of shrub and herb layers increased significantly before 15th year and then declined sharply,but did not change significantly from 20th to 30th years.Coverage degree of herb layer was higher and its spatial heterogeneity was lower compared with shrub layer.Biomass of shrub layer increased significantly before 15th years,then decreased from 15th to 20th year,and eventually stabilized from 20th to 30th years.Biomass of herb layer fluctuated from 10th to 30th years and tended to decline with plantation age.The results indicate that structures and functions of understory vegetation tend to degenerate with growth and development of the mixed alder and cypress plantations.

Abstract:The distribution of diameter class,stand canopy,and undergrowth plant diversity in Robinia pseudoaeacia plantation with different densities in the hilly area of the Loess Plateau were analyzed.Results show that the breast diameter class of stands presents a normal distribution when density of young-aged stands is 2 800 trees per hectare and a nearly normal distribution when density of young and middle-aged stands is 700~900 trees per hectare.Under the condition of the same stand age and site,leaf area index increases,while transparency and diversity and evenness index of plant species beyond forest canopy decrease with increased stand density.

Abstract:The status of nutrient inputs and outputs on farmland of the Hexi corridor,Gansu Province was studied conclusively by a 24 year long-term location fertilizer experiment.Results showed that long-term continuous chemical fertilizer application made soil nitrogen(N) input—output change from a negative balance to a positive balance in the first period(1982—1990) and surplus rate was about 8.6%~19.1%.Apparent surplus rate was 29.0%~48.5% during the period with the largest balance value(1997—2005),but soil N input-output was in a negative balance after N loss was deducted.Phosphorus(P) fertilizer input—output was still in a positive balance and surplus rate was 57.4%~68.3%.Potassium(K) fertilizer input quantity was less than uptake quantity of crop,so K input—output was in a negative balance and averaged surplus rate was-58.7%.These indicated that N and K nutrient inputs were not enough by continuous chemical fertilizer application.The long-term combined application of chemical fertilizer and organic manure could make N and P input—output be in a positive balance and surplus rates of N and P were 56.3%~61.5% and 249.9%~265.7%,respectively.Even though N loss was deducted,N surplus was still 9.4%~10.9%.K input—output was in a negative balance and average deficiency was 19.9%.Under continuous organic manure treatment,K deficiency was 45.0%.Increasing K chemical fertilization,keeping N chemical fertilization level,and combining organic manure application are scientific balanced fertilizer application techniques.

Abstract:Pot experiment in outdoors was conducted by comparing 5 kinds of poplar(P.liaoyu 1,938-18,P.×gaixianensis,P.liaoyu 3,and"P.simonii×P.euphratica"×P.sp) to search for suitable tree species which can be adopted in the Cd contaminated region.There was no significant difference between treatments for seeding height and basal diameter.Moreover,there was no significant difference between treatments for biomass of 938—18,P.×gaixianensis,and"P.simonii×P.euphratica"×P.sp.However,biomasses of P.liaoyu 1 and P.liaoyu 3 were affected significantly by Cd.At the Cd contamination level of 150 mg/kg,their biomasses were significantly decreased.At the level of 5 mg/kg,seedling's biomasses of P.liaoyu 1 and P.liaoyu 3 were the heaviest,so the lower Cd density may increase seedling's biomass and the higher Cd density may repress seedling growth.There was no influence on the amounts of roots of 938—18 and "P.simonii×P.euphratica"×P.sp,but Cd 2+in soil may activate rooting of the rest kinds of poplar.

Abstract:In order to investigate the influences of thinning on soil quality in young Pinus tabulaeformis plantations and to provide a reference for reasonable thinning,a thinning experiment was conducted in the 18-year-old Pinus tabulaeformis plantation in lower hilly lands of Yingpan and Yanqing County,Beijing City.Four different thinning treatments(0,35.7%,49.2%,and 64.2% thinned) were carried out in the stands of 3130 tree/hm2 initial density.In 2005,the 3rd year after thinning,soil physical properties,chemical properties,and soil enzyme activities in the four sample plots were studied.Results showed that thinning has significant effects on soil quality in the 18-year-old Pinus tabulaeformis plantation.The thinning would improve capillary spaces and water-holding capacities.Along with the density decreasing,soil organic matter,available K,and available P increased significantly.The catalase,polyphenol oxidase,urease,and alkaline phosphatase activities increased along with the thinning increasing.Results from principle component analysis revealed that soil catalase,urease,and available P could be regarded as indicators to assess soil quality affected by thinning.In the plantations of decreased reserve density,the integrated fertility indexes of soil quality properties were-1.061,0.032,0.347,and 0.682,respectively,among which the 64.2% thinning intensity was the best.

Abstract:Grain-size can be applied to identify types of deposition environment and to determine ways of material movement.Based on the investigation on the beach of Weihe River in Xianyang section,and the analysis of grain-size for 53 collected samples,the characteristics of flood sediment were analyzed,including grainsize distribution,grain-size parameter,and grain-size frequency curve.Results showed that the thickness of modern time flood sediment in the Beibuzi section of Weihe River was about 2.16 m.For the grain-size composition,the content of medium size sand was the highest,its grain-size was in the thick range,and its size sorting was worse.Based on the analyzed material,the development of flood sediment was better over the past 30 years.

Abstract:Temperature in the Dongzhiyuan region has increased remarkably since 1990s,with the linear trend being 0.099 5 ℃/a.In terms of warming amplitudes and significance decreased,spring,winter,summer,and autumn were ranked in descending order.Annual precipitation varied like a V-type parabola.The middle and late 1990s was a dry period,especially in spring and autumn. The wet year and dry year changed with a cycle of about two years from 1998.Due to the increase in temperature and decrease in precipitation,soil moisture in winter wheat fields was reduced year by year during the growing season in spring.Soil moisture in tillage layer was reduced consistently year by year in early spring and soil moisture within 30 cm soil layer,in the period of late spring and early summer.Besides,soil moisture changed with precipitation amount in other periods.Although the inter-annual variation of soil moisture was different in different time,soil moisture in winter wheat fields varied like V-type parabola in each year.Soil water content was decreased to the lowest in June,which is the mature period of winter wheat,and then it was gradually increased in autumn.However,soil moisture changed as a linear trend in 1998 and 1999.Agricultural production is affected by soil water conditions(surplus or deficit) which are affected by climate change again.Results from the study also show that agricultural production changes with soil moisture conditions.

Abstract:Soil erosion by wind is one of the main natural disasters on the sandy land in West Jilin Province.Based on field investigation,tests,and indoor wind tunnel experiment,the mechanism of soil erosion by wind on sandy land is analyzed.Analyses indicate that soil erosion by wind constantly decreases with the increases in surface roughness,soil moisture content,and organic matter content.A negative exponential relation with surface roughness and soil moisture content and a negative relation with organic matter content are found.Wind is the main force driving soil erosion on the sandy land in the region.When wind velocity exceeds the critical velocity,soil erosion is proportional to the third power of wind velocity.Climate factor for soil erosion by wind is 155.2.Erosion in spring is the severest(76.2).Spatially, both erosive climate factor and erosive wind energy increase from west to east. Yutong County in the northwest part of the region has the greater values.

Abstract:In the light of the characteristics of cold plateau,we study the planting composition of tree species and the choice of tree and herbages species,as well as the techniques of site preparation,fighting-drought forestation coverage,and new fighting-drought materials in the low forest region of Datong County,Qinghai Province.As a result of the study,the integrated forestation technology suitable for the cold plateau and the low mountains of the loess hilly region is suggested.The technology can provide a technical base for the Project of Converting Slope Farmland into Forestland in both the region and other similar regions.

Abstract:Through the analysis of hydrological characteristics of watersheds in the upper reaches of Fenhe River,a distributed hydrological model at a catchment scale was constructed.The runoff yielding and sink flow model of SCS and the Muskingum method were firstly combined to determine discharge process in the area.Moreover,taking slope angle and slope orientation as the main indexes,a watershed was divided into sub-catchments by natural draining divide.To test accuracy of this model,the catchment of the Lanhe River in the area was chosen as a typical catchment.Results show that calculated runoff yielding and sink flow account for 70% and 80% of the observed dada,respectively,and simulated discharge process is basically coincident with observed discharge process.The model is suitable to modeling runoff yielding and sink flow in the area.

Abstract:Laboratory triaxial tests were carried out to obtain the stress-strain relationship of grassroots-reinforced soil(GRS).BP neural network constitutive models of soil and GRS reinforcement in mixing were established based on test data.The result from comparing predicted values and measured values shows that the network constitutive model has good fitting precision and good generalization ability and can fully describe the non-linear relationship of geo-materials. The shear strength indexes of GRS fitted by Mohr-Columb criterion may be used to analyze the mechanism of GRS protection of slope.The research results are of importance for establishing the constitutive model of GRS and understanding the mechanism of vegetation protection of slope.

Abstract:Soil water dynamics is one of the important indicators of reclaimed land quality.This paper is concerned about water dynamics in overlying soil with filling layers of different porosities by simulation experiment.Results indicate that water loss is faster when the filling layer porosity is slightly less than that of overlying soil.On the contrary,water loss is positively related to porosity when the filling layer porosity is greater than that of overlying soil.So,in order to keep more water in overlying soil in filling reclamation,filling layer porosity should be designed according to the porosity of overlying soil.

Abstract:Parameter determination is the prerequisite for the simulation of rainfall and runoff in a hydrological model. Model and parameter uncertainty should be considered during that procedure. This paper started with an introduction of the theory on the multi2objective complex evolution (MOCOM-UA) algorithm of excellent global and local optimization capability for dealing with the complex problem of hydrological model calibration. Based on the Xin’ anjiang model , different searching mechanisms between the multi-objective approach based method and genetic and simplex algorithm were respectively discussed by rainfall-runoff simulations for the Baohe watershed in the upper reaches of the Hanjiang River basin. With the application of the multi-objective genetic algorithm coupled with the simplex method as an optimal solution , the Pareto space of parameters and the prediction extent of the model were calculated and analyzed under four objective function conditions. The uncertainties of the model and its parameters were preliminarily investigated.

Abstract:Parameter determination is the prerequisite for the simulation of rainfall and runoff in a hydrological model.Model and parameter uncertainty should be considered during that procedure.This paper started with an introduction of the theory on the multi-objective complex evolution(MOCOM-UA) algorithm of excellent global and local optimization capability for dealing with the complex problem of hydrological model calibration.Based on the Xin'anjiang model,different searching mechanisms between the multi-objective approach based method and genetic and simplex algorithm were respectively discussed by rainfall-runoff simulations for the Baohe watershed in the upper reaches of the Hanjiang River basin.With the application of the multi-objective genetic algorithm coupled with the simplex method as an optimal solution,the Pareto space of parameters and the prediction extent of the model were calculated and analyzed under four objective function conditions.The uncertainties of the model and its parameters were preliminarily investigated.

Abstract:The LNG station-pipeline project is the typical linearization project. According to the characteristics of the project,monitoring scope of soil and water conservation,monitoring zone,monitoring-point layout,and monitoring content and means are described in detail.Results show that soil and water conservation measures have played an important role and soil erosion prevention and control reach the target value.By monitoring analysis,some suggestions are presented for the similar programming design of engineerings.

Abstract:In order to make an objective and holistic environmental evaluation of hydraulic engineering projects,the Yanshan Reservoir project,which is one of the key projects of Huaihe River harnessing,was taken as an example in this study.Principles and the method of impact scope and degree were analyzed based on the analysis of soil loss impacts on the construction area of the project.A comprehensive evaluation model of the impacts was preliminarily established.It can provide a holistic and quantitative result of impact evaluation for the project.By using this method,some shortcomings by using the single factor analysis method can be overcome.

Abstract:A field experiment under simulated rainfall was carried out to assess the characteristics of pollution and runoff yield at five different rainfall intensities on barren grassland slope in Qingshan catchment,Lin'an City,Zhejiang Province.Results showed that runoff volume was positively correlated with rainfall intensity and the correlation coefficient was 0.873 2.Sediment concentration in runoff was not significantly correlated with rainfall intensity.Pollutants ranked in the descendant order of COD,TN,TP,and water-soluble P in terms of concentration and the concentration became smaller and smaller with increased rainfall intensity,which means that rainfall can dilute pollutant concentration.The secondary pollutant modulus of different pollutants was positively correlated with rainfall intensity and the correlation coefficient was above 0.9,which showed that pollutant was bigger with the increased rainfall intensity.

Abstract:USLE is a better and widely used model for forecasting soil erosion.Rainfall erosivity and its distribution characteristics is the key to the application of USLE in soil erosion research in a large area.Based on the daily rainfall erosivity model,the average monthly and annual rainfall erosivity model for the Loess Plateau is established.Using the daily rainfall data from 235 weather stations from 1971 to 2000 on the Loess Plateau,we estimated the monthly rainfall erosivity and the annual rainfall erosivity,which were used to interpolate a spatial distribution map by the Kriging interpolation method.The spatial pattern of rainfall erosivity was also analyzed for different topographic regions.Results show that there is a descending trend from southeast to northwest in spatial pattern of rainfall erosivity on the Loess Plateau.Rainfall erosivity on the Loess Plateau is between 300 and 7 500,with an averaged value of less than 3 000.The topographic units,from large to small,are rock mountainous area,hilly gully area(Yan'an),high plateau gully area,hilly gully area(Yulin),and hilly gully area(Longxi).Rainfall erosivity is mainly concentrated in July and August.Cycle analysis indicates that there is a 2.7-year undulating period of rainfall erosivity in the entire region and the undulating range of rainfall erosivity is more than twice of annual average value.There are distinct differences among different regions.

Abstract:Investigation of sediment transport balance in the Guanting Reservoir watershed indicated that in the past fifty years,the total sediment yield resulting from soil and water loss was 4.565 billion tons.Soil and water conservation measures kept about 0.771 billion tons,16.89% of the total sediment yield.Water conservancy projects retained about 0.765 billion tons,16.76% of the total sediment yield.Irrigated lands intercepted about 0.965 billion tons,21.14% of the total sediment yield.River beds and courses accepted about 0.816 billion tons,17.88% of the total sediment yield.The reservoir trapped about 0.75 billion tons,18.02% of the total sediment yield.The reservoir discharged about 0.425 billion tons,9.31% of the total sediment yield.The amount of sediment retention by soil and water conservation from 1981 to 2000 increased about 26.27% in comparison with that from 1950 to 1980,which indicates that sediment retention has increased significantly in the recent 20 years.

Abstract:The pollution status of soil heavy metals(Cu,Pb,Zn,Cd,Cr,Hg,and As) under different landuse types and different soil types in Xiangtan City was investigated.Results showed that for the 54 samples,pollution by Cd and Hg was in a heavy stage,pollution by Cu and Zn reached a moderate stage,pollution by Cr was in a light stage,and pollution by Pb and As were still in a proximity clean zone.For different landuse types,pollution by Cd and Hg was most serious,which was between medium and heavy pollution stages,pollution by Pb stayed in a clean zone or proximity clean zone,and pollution by other metals was in a slight or proximity clean zone.For different soil types,pollution by Cd and Hg were heavy,pollution by Zn was moderate,pollution by Pb was in a clean or proximity zone,and pollution by other heavy metals was between slight and proximity clean zones.As a whole,pollution by heavy metals of Cd and Hg is heavy in Xiangtan City,which is probably caused by the "three wastes",automobile exhaust,fertilizer application,and sewage irrigation.

Abstract:Classification of soil erosion is an important topic in soil and water conservation.Since the classification standards,such as obvious demarcation lines,choice of factors,determination of weights,and the degree and range of soil erosion,are fuzzy,classification of soil erosion evaluation model is made by matter element analysis based on the subject function of fuzzy.Moreover,the specific application of the model is introduced in contrasting with fuzzy comprehensive evaluation model and actual examples.Results show that the model is rational and feasible.

Abstract:Through investigation and analysis,the importance of environmental regionalization for natural hazard prevention and treatment has been revealed.Based on the work,principles for highway flood hazard environmental regionalization,such as regional differentiation,similarity,integration of comprehensive analysis,dominant factors,and practicability,are put forward.According to the principles,the index system for highway flood hazard environmental regionalization in Chongqing City is studied systematically.Based on the causes of highway flood hazard,a two stage index system is established by using Delfei method.The weight of each indicator is determined in the light of its relation with highway flood hazard by using analytic hierarchy process.The classification system of the secondary indicator including 5 grades is set up based on the outcome of in-situ investigation and analysis of historical data.The value of the secondary indicator for each grade is also determined by using Delfei method and thus the methodology for calculating synthetically the value of highway flood hazard environmental regionalization is formed.The classification and corresponding criterion for highway flood hazard environmental regionalization are brought forward subsequently,which provide a basis for environmental regionalization work.

Abstract:In order to dynamically monitor soil erosion and determine the relationship between landuse and soil erosion in Baota District of Yan'an City,an analysis was performed using the data from TM images in the two periods of 1997 and 2004.Results show that soil erosion occurred in cultivated land,forestland,grassland,and orchard.The area of cultivated land decreased and the areas of woodland,grassland,and orchard increased from 1997 to 2004.The area of soil erosion decreased and its grade descended.Generally speaking,landuse and soil erosion control in the study area develop towards a good direction.

Abstract:This study focused on water quality in 11 typical sections of Shaxi River,Minjiang River basin and developed an attribute recognition model by applying attribute recognition theory and attribute recognition guild lines.Results showed that water quality in 8 sections was up to the third class of the national water quality standard of China,which may be considered as drinkable water resource.By contrast,water quality in other 3 sections did not reach the third class of the national water quality standard.The result was similar to that from the analysis of fuzzy membership function.It demonstrated that the method of attribute recognition model was suitable for assessing water quality.Finally,according to the absorbency values of 11 water samples under 254 nm,mineral matter was the dominant pollutant.

Abstract:Using grassland area,stock number,and productive expenditure as inputs and per capital annual net income,life expenditure,and grassland quality as outputs,we analyze 30 household pastures in Baiyinxile of Inner Mongolia by means of CCR,a model of data envelopment analysis(DEA),and get the improved values of indicators.Results show that production efficiency is correlated with the grassland area possessed by households.The area of grassland less than 200 hm2 has high production efficiency.Under the assumption of no change in grassland quality,the two-level DEA validity suggests that the three input indicators decrease by 22.28%,21.83%,and 28.62%,respectively,and the first two output indicators increase by 0.78% and 0.91%,respectively.Moreover,the 1st DEA validity shows the three input indicators decrease by 49.86%,47.29%,and 60.79%,respectively,and the first two output indicators increase by 33.50% and 7.06%,respectively.Optimizing management and enhancing production efficiency in household level may play an important role in mining the potentials of household pastures and improving eco-environmental construction of natural grassland areas.

Abstract:By taking a typical loess hilly-gully area—Zhaozhuang village in Yan'an City as a study area and selecting indexes such as dynamic degree of landuse,trend-state index of landuse,and landscape index of landuse,dynamic changes of landuse were analyzed quantitatively on village scale.Results showed that landuse in the study area changed to some extent during the past 6 years,which was characterized mainly by decreased farmland and increased unused land.Unused land,resident-construction land,forest land,and shrubby and grass land increased in varying degrees and their dynamic degrees were 43.92%,15.35%,0.33%,and 0.17%,respectively.Farmland,orchard,and water area decreased in different degrees and their dynamic degrees were 7.45%,3.79%,and 0.20%,respectively.The trends of farmland,orchard,and water area dropped,while the trends of unused land,resident-construction land,forest land,and shrubby grassland raised,which scales were increscent.Patch number and patch density increased.The dominance index and deviation index decreased while the indexes of diversity,evenness and fragmentation increased to some extent.

Abstract:Ecological footprint is an important indicator to evaluate the sustainable use of ecosystem.Based on the theory of ecological footprint,the ecological footprint and ecological capacity of the Yangtze River Delta during the period from 1996 to 2004 are calculated and analyzed using the method of variable world average yield.Results show that the ecological deficits continue to increase,which demonstrates that great human-environment conflicts exist.The Yangtze River Delta is in a state of unsustainable development.

Abstract:By using the related methods,soil conservation functions and service values of the afforested vegetation by enclosure at the Wufendigou experimental base in Huangfuchuan watershed were calculated.Results showed that the volume of controlled soil in the study area was 89.45 t/(hm2·a) and the total benefit of soil conservation was up to 77.09%.The sequence of vegetation type,in terms of the controlled soil volume from high to the low,was grassland,shrub woods,arbor woods,and bare land.The value of controlled soil per year was estimated to be as much as 856 780 yuan and the values of controlled soil nutrients,reduced land disuse,and reduced sediment were about 822 925,30 234,and 3 620 yuan,respectively.The sequence of vegetation type,according to the contribution of vegetation type from high to low,was shrub woods,bare land,grassland,and arbor woods.The value of controlled soil was 2 050 yuan/hm2 and the values of controlled soil nutrients,reduced land disuse,and reduced sediment were about 1969,72,and 9 yuan/hm2,respectively.According to the contribution of vegetation type from high to low,the sequence was shrub woods,grassland,bare land,and arbor woods.

Abstract:Based on field investigation,trace recording,and experimental data analysis,ecological economic principles are applied to study ecological economic benefit of fruit-pig-methane compound management mode in the southern loess hilly gully region.The results indicate that the mode can ameliorate soil in a certain degree and increase soil porosity and the contents of soil nutrients.It can also increase the percentage of excellent and commodity fruit and reduce the percentage of abnormal fruit and the times of diseases and pests.The mode can increase renewable biogas energy,so it can reduce fossil fuel demand and protect environment.The mode has a great economic value.It can increase rural people's incomes and the economic benefit of apple orchard.In a word,the fruit-pig-methane compound management mode has a great eco-economic benefit and may make great contributions in new rural reconstruction.

Abstract:Based on landuse change data obtained from TM images in 1986 and 2003 and the relative ecological values of corresponding landuse types,we evaluated ecological effects of returning farmland to forest or grass land in Wuqi County. Results show that landuse types in the county were in a significant change during 1986-2003.The total area of woodland and grassland has increased greatly while the area of farmland and unused land has significantly reduced.There was 63.55% of farmland transferred into woodland and grassland.Ecological environment has been significantly improved and overall environmental quality has been remarkably improved.Ecological contribution rate of returning farmland to forest is 40.96%. Projects of returning farmland to forest land in Wuqi County have achieved success and brought wonderful ecological effects.

Abstract:Guizhou Province is located in the karst mountain area and a large quantity of surface water leaks because of the karst environment.It is difficult to develop its water resources and thus its water resource availability rate is very small.It is known that the population and the GDP that water resource availability can carry are far beyond what the gross water resource can carry.The amount of gross water resource in the province is abundant,but the population that water resource availability can carry is far beyond its ability.The provincial economy can not satisfy the needs of people because of its underdevelopment.Population is a most important factor that restricts the development of Guizhou Province.The large population and the undeveloped economy matching with the karst environment lead to the unsuitable matching conditions of water resources,population,and economy.

Abstract:The Chaohe River basin,which accounts for 31% of the area of upper Miyun Reservoir catchment,was selected as the study area.Effects of soil and water conservation on reducing soil and water loss,improving ecological environment, and increasing local social and economic benefits were studied by analyzing the status of soil and water conservation,as well as soil and water loss.Some problems existing in soil and water loss control in the Chaohe River basin were expounded in order to provide policy enlightenments for comprehensive watershed management.

Abstract:Regional development evaluation is a complicated systematic project involving constructing evaluation index system,assigning index weight,standardizing data,designing evaluation index,grading standards evaluation,etc.By taking Ningxia Hui Autonomous Region as a case study,firstly,a framework for regional development evaluation was designed in the three aspects of comprehensive,coordinated,and sustainable developments.Secondly,basic indicators were selected by frequency-statistics method and correlation-analysis method.Thirdly,weights of indicators were assigned by improved analytic hierarchy process(9/9—9/1).Fourthly,the"standard figure" method was put forward in order to make the results comparable in the country-wide range.Fifthly,a set of indexes were designed to evaluate regional development from different perspectives and levels.Finally,the development of Ningxia Hui Autonomous Region since 1990 was evaluated using the evaluation system.

Abstract:The distribution,type,and salt characteristics of inland saline soil in the Hexi corridor were analyzed.Experiments of bioremediation and control were conducted with the alkali meadow grass planted in saline soil for 3 years.Contrasted with control group,topsoil desalination rate was up to 77.00%;pH value decreased 0.25 pH unit;soil bulk density decreased 0.14 g/m3;total porosity increased by 5.29%;soil aggregate structure increased by 23.14%;soil water content increased 70.30 g/kg;average triennial alkali grass yield was 36 000 kg/hm2(fresh weight).In addition,planting forage in saline soil as a medium and establishing a compound agro-forestry-animal system promoted the sound combination of planting industry,forestry,and livestock husbandry.Because of the reasons,utilization ratio of land reached more than 184.00%;the income of land increased from 16 300 to 35 500 yuan/hm2;average income per farmer in the controlling region increased by 66.00%,from 2 160.70 to 1300.80 yuan.