Abstract:Climate change will have considerable impacts on soil erosion on the Loess Plateau and assessing the possible impacts may provide useful information for agriculture production.The objective of this study was to simulate the response of slope erosion(5°and 10°) on the loess tableland during 2010-2039 based on HadCM3(Hadley Centre Coupled Model,version 3)and WEPP(Water Erosion Prediction Project)model.GCMs predicted a 1.8% to 17.5% increase in annual precipitation,0.5℃ to 0.9℃ rises in maximum temperature,and 2.0℃to 2.3℃rise in minimum temperature for the region.Compared with the present climate,the runoff and soil loss of May and August to October will increase greatly.Percent increases,as averaged for each emissions scenario and slope,ranged from 51% to 117% for annual runoff and 31% to 170% for annual soil loss.Climate change will exacerbate soil and water loss in hillslopes on the Loess Plateau and some countermeasures are necessary to mitigate the adverse effects of climate change.

Abstract:Organic carbon change and distribution of soil aggregates were analyzed under different land uses such as arable,garden plots,woodland,and abandonment land by field investigation and indoor analysis.Results indicated that by the percentage,the size groups of soil aggregates were in the order of>5,2～5,0.5～1,1～2,<0.25,and 0.25～0.5 mm and by the organic carbon content,the size groups were in the order of>5,2～5,1～2,and 0.5～1 mm in the>0.5 mm size groups.In the <0.5 mm size groups,the organic carbon change was relatively complicated.The organic carbon content in arable land,woodland,and abandonment land was the highest in <0.25 mm fraction of soil aggregates.The organic carbon content in the garden plot was the highest in 0.25～0.5 mm fraction of soil aggregates.The difference was the largest in>5 mm fractions of soil aggregates among the four land uses and the difference decreased with the increasing aggregate size.Under different land uses,the proportion of the organic carbon and total organic carbon for the <0.25 and 0.25～0.5 mm soil aggregates was lower than that for 2～5,>5,and 0.5～1 mm soil aggregates.

Abstract:LI26400 portable photosynthesis measurement system and its soil respiration fitting 6400209 are employed to measure and analyze the soil respiration rate of the Cupressus funebris forests,shrubs,mixed broadleaf,mixed conifer and broadleaf,and Pinus massoniana forests in the karst areas of central Guizhou in winter.Results indicate that there are differences in the diurnal change range among the different forest types and different months.The diurnal change range of shrubs in February is the highest,from1.65 to 2.37 μmol/(m²?s),and that of the Cupressus f unebris forests in December is the lowest,from 0.41 to 0.53 μmol/(m²?s).The maximum soil respiration rate is 1.2 to 1.5 times as much as the minimum respiration rate of most of the forest types in different months.The general features of soil respiration of the 5 forest types are that the soil respiration rate of the 5 forest types is the smallest in January,the middle in Decem2 ber,and the biggest in February ; the maximum soil respiration rate is 1.46 to 2.85 times as much as the minimum respiration rate ; and there is a great difference in soil respiration rate among different months of the same forest type and among different forest types in the same month.There are significant positive exponential correlations between soil respiration rate and the soil temperature at the 5,10,and 15 cm depths.Relations between soil respiration rate and soil volumetric moisture at different soil depths for all the forest types are considerably complex.The contribution percentages of litter to the total soil respiration rate arre from 6% to 36%,with that of January being the smallest,February,the middle,and December,the biggest.

Abstract:Based on indoor experiment under simulated rainfall,the characteristics of splash erosion by rain2 drops in typical soil and water loss regions of China are analyzed and the relationships between splash erosion and soil physical and chemical properties are discussed.Results show that splash erosion amount is affected obviously by soil physical and chemical properties.The splash erosion amount of black soil samples is the lowest because of their high aggregate content and aggregate stability.The splash erosion amount of loess soil samples collected from Dongsheng City,Inner Mongolia is the highest because they contain high content of sand particles easily to be splashed.The other loess soil samples,red soil samples,and purple soil samples correspond to the medium splash erosion amount because of the majority of silt particles or high content of micro-aggre-gates.Except for black soil sample and loess soil samples collected from Dongsheng City,Inner Mongolia,soil crust is developed in other soil samples under simulated rainfall,so,raindrop splash rate fluctuates with time.

Abstract:Infiltration is a key step to transform rainfall into soil water.Infiltration capacity in three typical soil and water conservation projects (88542 level furrow site preparing,fish-scale pit site preparing,and level terrace) in the loess hilly regions of Southern Ningxia Hui Autonomous Region is studied by means of double ring method.Results showed that infiltration capacity was significantly improved after implementing the soil and water conservation projects.By the capacity,the order of the three engineering measures was 88542 level furrow>fish-scale pit>level terrace.The infiltration models for the engineering measures were all accord with power-exponent equation.The changes in soil bulk density and soil porosity was the main cause of the change in infiltration capacity.The improvement degree of soil bulk density and porosity by the three measures has a high concordance with the change of infiltration capacity.

Abstract:In order to explore the effects of species configuration measures on the nature of soil hydrology in the project of conversion of cropland to forest land,soil porosity and the capacity of water-holding for 10-year-old Robinia p seudoacacia,Platycladus orientalis,and Pinus tabulaef ormis are determined using forest ring in the loss hilly region.Results show that (1) a variety of stands have significantly improved the capacityof water-holding,i.e.,the performance to reduce soil bulk density and increase soil porosity and soil water-holding.The greatest improvement is by Robinia pseudoacacia,the second is by Pinus tabulaef ormis stand,and the third is by Platycladus orientalis.(2) Increase in the amount of residual water of soil( non-capillary porosity) by various stands is greater than the degree of(capillary porosity) water retention.(3) The vertical spatial variability of forest soil is obvious.With the increase in soil depth,soil bulk density is increased,but soil porosity and water storage are reduced.

Abstract:The characteristics of runoff and dissolvable nitrogen and phosphorus losses from a Pinus elliottii stand were studied in Foshan City.The annual amount of runoff from the Pinus elliottii stand was 16.7 mm,which was mainly observed in summer.The relationship between rainfall and runoff in the stand could be described by a binomial equation.A logarithmic relationship existed between runoff and N concentration.Annual dissolvable N loss from the stand was 221g/(hm²?a) and in spring and summer,it reached its peak with above 80% of annual dissolvable N loss.Annual dissolvable P loss from the stand was 7.0g/(hm²?a).The greatest monthly dissolvable P loss occurred in May and June,2008,accounting 59% of its annual P loss.

Abstract:Effects of forest vegetation and small watershed ecological recovery on water and sediment variations in Beiluo River basin were studied.Results showed that forest vegetation could reduce runoff and sediment by 62.4% and 94.9%,respectively.Meanwhile,it regulated the annual distribution of runoff and released 20%～30% of runoff from flood season to nonflood season.However,flood sediment in forest region increased drastically under the effect of storm flood when forest was destroyed.In view of the effects of ecological recovery on water and sediment variation,the ecological recovery had a certain role in reducing water and sediment.

Abstract:The changes of soil nutrients and three community types(bushes,grass,and Robinia pseudoacacia)in the low mountain and hill district of Taihang Mountains are studied.By Shannon-Wiener index and the richness of the three community types,the communities are in a sequence of grass>shrub bushes>Robinia pseudoacacia and by the total coverage,the sequence is grass>shrub bushes>Robinia pseudoacacia.The contents of Zn,Mn,Na,Mg,and Fe in the three community types have no significant differences.Under the shrub bushes,the contents of Mn,Na,Mg,and Fe in subsoil are more than those in topsoil,but the differences are not significant except Zn.Under grass,the contents of Mn,Zn,and Na in subsoil are more than those in topsoil.Zn,Mn,Na,Mg,Fe,and organic matter are not significantly correlated.Mn and other nutrient elements,Fe and other nutrient elements(Na is significant correlated),as well as Mg and Na are all in extremely significant correlation.

Abstract:The natural chinese pine forest is an important vegetation type in vegetation protection and restoration of the Loess Plateau.To further understand its status and functions during its development process,the three main microgroups and the main functional groups of soils were investigated using the method of plate cultivation and MPN method.Besides,the soil microbial biomass carbon( MBC) was determined by the method of chloroform fumigation.Results showed that there was an increasing trend for the amounts of microorganisms and bacteria in the forest with the growth years from 10 to 25 and after that,they begun to reduce.Meanwhile,the amount of bacteria hold an absolute predominance over the total microorganism amount and the rest two types of microorganisms,fungi and actinomycetes,were fewer.The amounts of ammonifying bacteria and cellulose-decomposing microorganisms appeared in the forest with the growth years of 10 and after that they showed a decreased trend.The azotobacter amount showed an increasing trend in the forest with the growth years from 10 to 25,then decreased until 40 years forest,and after that showed a stable trend.There was no significant variation in nitrifying bacteria for the forest with the growth years from 10 to 40,but its amount significantly increased after that.Meanwhile,the comprehensive indexes of soil microorganism (Shannon) Wiener) and the MBC showed an increasing trend from 10 to 70 years.All above results demonstrate that there are a unique principle and the reasons of variation in soil microorganism composition in the natural chinese pine forest.This study may offer a guidance and reference significance to the protection and management of the natural chinese pine forest on the loess plateau based on soil microbiology.

Abstract:The effects of Seabuckthorn plant on gully soil improvement were studied by measuring soil organic matter data and employing the methods of comparison and statistic analysis.Field soil and water conservation experiment on Seabuckthorn plant flexible dam was conducted in the east2one2branch valley in the representative soft rock region of Zhungeer County,Erdos City,Inner Mongolia.Results showed that gully soil fertility can be markedly boosted and the growth environment of plant community can be strikingly improved by Seabuckthorn plant.The plant is very significant for the restoration and reestablishment of the region’s ecoenvironment.Idiographic conclusions are as follows:(1)The important resource of gully soil organic matter is the humus made of the multiple earth surface deadwood and defoliation from Seabuckthorn plant flexible dam and metabolism secretion of Seabuckthorn roots.(2)The mean organic matter in surface soil layer of 0-30 cm in gully with the Seabuckthorn plant flexible dam is 1.25 times over that of contrast gully.(3)The soil organic matter content has an increasing tendency from upstream to downstream in the east2one branch valley with Seabuckthorn flexible dam.(4) The mean soil organic matter content of all typical gullies with Seabuckthorn flexible dam in soil profile direction is about 1.8 times that of contrast gully.(5) The organic matter distribution in the soil profile direction is evidently changed by the growth of Seabuckthorn plant and this distribution can benefit the growth and restoration of Seabuckthorn plant and the attached gully plant community in soft rock region.

Abstract:Properties of humus and soil structure of five typical dark brown soil profile in“Three Parallel Rivers Area”were studied in the lab and through field survey as well to gain a better knowledge to protect the land resources in the view and provide a favorable basis.Results show that the content of humus and the distribution rule of organic carbon is the same,that is humus layer>leached layer>deposition layer>parent layers.Humin takes the major part in the Humus composition.HA have a higher degree of molecular complexity and chemical stability strong.The degree of soil humus and the complexity of the FA molecules and the chemical stability is the same,with the increase in annual rainfall decreases,followed by Haba Snow Mountain>Qianhu Mountain>Meili Snow Mountain>Yunling>Gaoligongshan.The content of water-stable aggregate are mostly content of 1～0.5 mm diameter,and the size of content and humic acid levels were elevated with the annual average temperature decreases,followed by Gaoligongshan>Meili Snow Mountain>Qianhu Mountain>Haba Snow Mountain>Yunling.Surface organic carbon is related to the content of the 1～0.5 mm size,humic acid and fulvic acid are also significantly related to particle size of 1～0.5 mm,0.5～0.25 mm content.

Abstract:The water holding characteristics of litter in the six young broadleaved stands of Cinnamomum camphora,L igustrum lucidum,Tsoongiodendron odorum,Elaeocarpus sylvestris,Manglietia yuyuanensis,and Michelia chapensis were studied.By the water holding capacity of litter,the stands was in the order of M.yuyuanensis woodland>M.chapensis woodland>L.lucidum woodland>T.odorum woodland>C.camphora woodland>E.sylvestris woodland.By the proportional water holding capacity as a percentage of the litter dry weight,the stands were in the order of T.odorum woodland>M.yuyuanensis woodland>M.chapensis woodland>C.cam phora woodland>E.sylvestris woodland>L.lucidum woodland.The total water holding capacity and proportional water holding capacity of litter increased logarithmically with increasing time immersed in water.Water absorption rates of litter in all plantations decreased with increasing time immersed in water by a negative exponential relation.

Abstract:Based on simulated rainfall experiment,the processes of soil erosion dynamic variation on the loess hillslope were studied and the following results were obtained:(1)Soil erosion rate was increased with rainfall process under different rainfall intensities and it could be described with a logarithmic and linear combined equation.15 min and 35 min after rainfall beginning were the turning points of soil erosion rate with rainfall process.(2)Soil erosion rate was increased rapidly with the increase of rainfall intensity at different slope gradients and it could be described with linear equation.(3)Soil erosion rate varied with the increase of slope gradient at different rainfall intensities,having a trend of increase to decrease,and it could be described well with a logarithmic and linear combined equation.The critical slope gradient was about 25°.(4)Soil erosion rate varied with the increase of slope length at different rainfall intensities,having a trend of increase to decrease,and it could be described well with a logarithmic and linear combined equation.80 cm of slope length is the turning point of soil erosion rate.(5)Effects of rainfall intensity,slope gradient,and slope length on soil erosion could be described with a ternary linear equation.The influence of rainfall intensity on soil erosion is more significant than slope gradient and slope length and slope gradient is more important than slope length.

Abstract:Litter storage and its water capacity are studied in the artificial black locust(Robinia Pseudoacacia)forest of different densities and ages in Tuqiaogou watershed of Fangshan County,Western Shanxi Province.Litter storage and characteristic parameters,such as water holding capacity and water absorption speed,are determined.Results show that by the litter amount,the artificial black locust forests of different ages are in the order of 9 years old forest>15 years old forest>20 years old forest.The quantity ranges from 1.89 to 9.30 t/hm2.By the maximum water holding capacity and the maximum rate of retention,the artificial black locust forests of different ages are in the order of 20 years old forest>15 years old forest>9 years old forest.Water holding capacity for the density of 3333 stands/hm² is the greatest and for the density of 1111 stands/hm²,the least.Undecomposed and half2decomposed litters absorb water very fast in the beginning 0.25 h;between 0 and 2h,water absorption speed drops quickly;and the speed slows down gradually and approaches to 0 after immersed for 24h.In the hilly and gully area of the loess plateau of Western Shanxi Province,the suitable stand density of artificial black locust forest is 1667 stands/hm².

Abstract:Erosive rainfall plays an extremely important role in forecasting and evaluating soil erosion by water.Erosive rainfall and rainfall erosivity (R) in Northern Jiangxi Province are studied based on data observed from 2001 to 2006.Results show that the rainfall amount standard and intensity standard of erosive rainfall events are 11.20 mm and 0.88 mm/h,respectively.The best equation for calculating rainfall erosivity factor in Northern Jiangxi is R=∑E.I₃₀.By calculation,the mean annual rainfall erosivity is 8695.43 J.mm/(m².h),maximum annual rainfall erosivity is 15140.64J.mm/(m².h),and minimum is 5601.10 J.mm/(m².h).The seasonal distribution of R value is mainly concentrated in summer.Through the simple algorithm of R proposed in the paper,percent change in annual rainfall erosivity is greater than percent change in total precipitation.

Abstract:The growth indexes of artificial black locust forest with different densities in the hilly and gully area of Western Shanxi Province are studied.The purpose is to provide theory and practice evidences for plantation management in the area.Results show that in the same stand age (20a),the values of various growth indexes in higher density forest is lower than those in lower density forest,such as tree height and crown width.However,the value of canopy density is higher than that in lower density forest.The DBH (diameter at breast height) of higher density forest is generally smaller and the DBH increases gradually with the decreased forest density.In the shrub layer and herb layer under different stand densities,plant average height,vegetation coverage,biomass,and species richness all decrease as the stand density increases.Soil water content in the undergrowth vegetation is higher in lower density than that in higher density.In the hilly and gully area of the loess plateau in Western Shanxi Province,the suitable stand density of artificial black locust forest is 1 667 stands/hm².

Abstract:The effects of salt stress on the characteristics of growth and protective enzymes were studied using Limonium bicolor (Bunge) Kuntze.seedlings.Five treatments were arranged:0,50,100,200,and 300 mmol/L.Results showed that (1) At 100 and 200 mmol/L salt stress,the roots length and leaves number of Limonium bicolor were 1.3 and 1.67 times of those of the control,respectively.Fresh weight and dry weight of roots (leaves) were significantly higher than those of the control.Fresh weight of roots and dry weight of leaves were the highest at 100 mmol/L salt stress,which were 1.35 and 1.6 times of those of the control,respectively.At 300 mmol/L salt stress,roots length and leaves number were 0.78 times those of the control and fresh weight and dry weight of roots (leaves),0.67(0.79) and 0.85(0.69) times of those of the control.The effects of salt stress on aboveground biomass were not significant.(2) With increased salt stress,the three protective enzyme activities of superoxide dismutase (SOD),peroxidase (POD),and catalase (CAT) of Limonium bicolor increased,which were the highest at 300 mmol/L salt stress and were 2.12,1.83 and 2.57 times those of the control.T he content of malondialdehyde (MDA) was 1.6 times of that of the control at 300 mmol/L salt stress.(3) The preliminary result showed that Limonium bicolor was a strong salt-tolerance plant and could grow at the salt concentration of 300 mmol/L.

Abstract:Triaxial shear tests were conducted to measure stress-strain curves under the consideration of loess structural differences in different regions.Three different typical loess areas of Luochuan,Lanzhou,and Yangling were selected.Based on Duncan2chang hyperbolic model,a simple way was adopted to determine structural parameters,which is better to reveal the changes and factors of structural parameters.The change in the structural parameters of the three regions was found.Results showed that unsaturated loess structural parameters firstly decreased with the increase in shear strain and then remained at a stable level.Water content and consolidation stress had significant influences on structural parameters.Under the same pressure condition,the lower the moisture content,the greater the structural parameters of loess and under the same moisture condition,the smaller the pressure,the greater the structural parameters of loess.As far as different regions are concerned,the strongest structural characteristic of loess under the same conditions was Yangling loess and it was followed by Luochuan loess.Lanzhou loess structure was the weakest.

Abstract:By taking the ecological slope protection of Ji'nan - Laiwu expressway located in the semi2arid region of middle Shandong Province as a research object,the vegetation restoration of rocky slope by external-soil spray seeding technique is investigated based on the ecological slope restoration observations.Results show that the succession process of secondary vegetation restoration is more rapid than natural vegetation restoration.By calculating and measuring the important value,niche breadth,and niche overlap of species,rocky slope has gradually evolved into the grass2shrub vegetation with importance value,such as alfalfa,tall fescue,amorpha,perennial ryegrass,and indigofera pseudotinctoria,which range from leguminosae grass to leguminosae and gramineae grass and from multi-grass type to grass-shrub vegetation.The weak competition among species for resources proves that plants during one and a half year's vegetation restoration period remain in the primary stage of succession process.

Abstract:The structural characteristics and species status of the Pinus armandii community widely distributed in the phosphorus mineral area of Fuxian lake watershed are analyzed for the reasonable vegetation structure with stable system.Results show that the quantity,structure,and growth of the Pinus armandii community are perfect,so it is a good vegetation community in the phosphorus mineral area for vegetation restoration.The optimum species disposition plan of Pinus armandii community is then developed.In the plan,the Pinus armandii,Lithocarpus dealbatus,Rhododendron siderophyllum,Ternstroemia gymnanthera,and Ficus ticoua in Pinus armandii community are used as dominant species and the local species resistant to leanness soil are used as the associated species for vegetation restoration in the area.

Abstract:Soil and water loss has become one of the usual issues of the environment in mountain tourism region.The mountain tourism destination is divided into tourism landscape functional zone,prelude space functional zone,eco2environmental protection functional zone,and mixing mountainous landscape functional zone.The different types have the different characteristics of soil erosion.The paper puts forward four patterns of soil and water conservation,i.e.,the pattern of tourism area,the combined pattern of agriculture and tourism of prelude space,the natural pattern of eco2environmental protection function zone,and the agriculture based economic pattern of mountainous function area.The study may provide a reference to rational ecological construction in soil and water conservation.

Abstract:By considering the three objectives of ecology,economy,and society in soil and water conservation,the two principles of guaranteeing regional grain self2sufficiency and increasing vegetation coverage,as well as the current status of soil and water loss in the Chaohe River basin in 2005,the three allocation plans of food grain security plan,eco2priority plan,and comprehensive plan are established,as soil and water conservation measures.Impacts of the three allocation plans for soil and water conservation on annual runoff of the Chaohe River are simulated and analyzed based on the water reduction norm of level terraces and forest-lands under different precipitation schedules.Results show that if all the soil erosion areas are converted to artificial woodland,the impact to annual runoff reduction is greater,with the reductions in wet year,normal year,and dry year being 8.27 %,8.28 %,and 11.13 % of the annual average runoff,respectively.Adopting comprehensive allocation plan may affect annual runoff greatly and the reductions in wet year,normal year,and dry year are 11.42 %,8.38 %,and 13.21 % of the annual average runoff,respectively.The impact of grain security allocation plan on annual runoff reduction is littler and the reductions are 7.59 %,6.03 %,and 9.11 % of the mean annual runoff during wet year,normal year,and dry year,respectively.

Abstract:Under the arid conditions,transpiration of plants can cause substantial loss of water.Semi-arid loess areas are the key areas for the returning farmland to forest and eco-forestry projects.In these areas,however,potential evapotranspiration is stronger and precipitation is less than other areas.Artificial afforestation is confronted with great difficulties.Spraying the new anti2transpiration foliar fertilizer may provide the necessary nutrients,inhibit transpiration,improve plant water potential,and to some extent,improve the viability of plants.The study uses Rhus ty phina,Robinia pseudoacacia,and Ulmus pumila to investigate the effects of the three foliar fertilizers.It is found that the best formulation is self2made A or self-made B +Ulmus pumila + 300～1 200 times diluted + 10 %～25 % soil moisture.

Abstract:Wind-sand hazard is a common natural disaster in northwest region of China.Minqin,Gansu Province and Yanchi,Ningxia Province,which are the typical areas of wind erosion,were selected to investigate wind prevention by the northwest shelterbelt.The wind prevention of the schistose shelterbelt in farmland with different heights from ground and in different structures were observed and moreover,the windbreak and sand-fix forest that may influence ground roughness were studied.The methods of sample area survey,statistical analysis,and regression model were used in the investigation.We found that the wind prevention of shelterbelt increased along with raising height from ground in valid windbreak distance ; the degree of porosity belt with its wind prevention presented a very significant negative correlation and the related coefficient was 0.941 ; and ground roughness increased with the raising crown density of windbreak and sand2fix forest.Moreover,the function of ground roughness and the crown density of forest was given.Some simple discussions were made according to the above mentioned results.

Abstract:Several suggestions are presented through the analysis of plantation production situation of artificial locust and its updating and succession processes in Wangdong watershed.The construction of locust forest should be combined with its updating during the forest2grass vegetation construction in the gully area of the loess plateau.The measures like clear-cutting and rootsprout and preferred thinning-cutting should be taken to update it.Cutting and reasonable use of locust forest should be based on second-generation locust forest growth and water use situation.At present,it is not adequate to cultivate the third generation.It is better to preserve herb and shrub plants so that it is replaced by a natural herb community firstly.The roles of vegetation in preventing soil erosion should be played at the same time in order to improve the ecological environment.

Abstract:Diurnal changes of photosynthetic rate(P_n) and transpiration rate(T_r) were measured using Li-6400 portable photosynthesis system to study the characteristics of physiological ecology of the apple trees in full fruit period under different soil management models.The relationships of photosynthetic rate(P_n) and transpiration rate(T_r) with environmental factors and physiological factors were analyzed by correlation analysis.Results showed that the diurnal changes of photosynthetic rate(P_n) presented the double-peak curve for clean tillage treatment and growing grass treatment.The diurnal changes of photosynthetic rate(P_n) in film mulching,straw mulching,and gravel mulching presented the one-peak curve.The diurnal changes of the transpiration rate(T_r) presented the one-peak curve.The relationships of photosynthetic rate(P_n) with photosynthetically active radiation (PAR),air temperature(T_a),and leaf temperature(T_l) were the quadratic curve.Photosynthetic rate(P_n) was significantly positively correlated with atmospheric relative humidity (RH) and stomatal conductance(G_s),respectively,and was significantly negatively correlated with intercellular CO₂ concentration (C_i).The relationship of transpiration rate(T_r) with photosynthetically active radiation (PAR) was power exponent and with atmospheric relative humidity (RH),was the quadratic curve.transpiration rate(T_r) was significantly positively correlated with air temperature(T_a),leaf temperature( T_l),and stomatal conductnce (G_{s),respectively,and was significantly negatively correlated with intercellular CO2 concentration(Ci).Photosynthetic rates(Pn) for gravel mulching and straw mulching were the highest and there were little difference in the average diurnal change of transpiration rate(Tr) under different soil management models.The photosynthetic characteristics showed a significant correlation with environmental factors and physiological factors,respectively.}

Abstract:The difference between conventional permeability test and triaxial permeability test is studied and the characteristics of saturated loess permeability affected by stress field by confining pressure are analyzed.The loess samples from the four typical loess areas of Lanzhou,Luochuan,Yangling,and Gongyi were fully saturated to make conventional variable-head permeability test and triaxial permeability test.Results show that with the increases in confining pressure and dry density,the permeability coefficient of saturated loess decreases.In general,when dry density changes from 1.45 g/cm3to 1.65 g/cm3and confining pressure,from 100 to 400 kPa,the permeability coefficient by triaxial permeability test is almost 0.881 to 0.161 times less than the test result of conventional permeability.

Abstract:Using the entropy model and grey correlation analysis and taking Langzhong City,Sichuan Province as an example,this paper analyzes the structure of landuse changes and the response mechanisms in the city.The grey correlation analysis indicates that the information entropy of landuse structure in Langzhong City was stable during the last decade.From 1997 to 2002,landuse structure entropy was closely related to per-land GDP,road density,retail sales of consumer goods,proportion of non-agricultural population,land economy density,ratio of non-agriculture and agriculture,and the correlation degree of above 0.70.The entropy was moderately related to per-capital GDP,with the correlation degree being 0.657 69.However,between 2003 and 2006,landuse structure entropy was moderately related to all the above seven factors,with the correlation degree ranging from 0.35 to 0.70.Further research suggests that socio-economic factors and government action are two main driving forces to the changes in landuse structure.

Abstract:Based on data observed from the automatic meteorological station near runoff plots and measured soil loss data from field runoff plots at Binxian Experimental Station in 2008,runoff and soil loss from the plots in black soil zone,Northeast of China were simulated.The simulation results were compared with measured values and the applicability of WEPP model was assessed.Results showed that Nash -Sutcliffe model efficiencies of event runoff simulation on different slopes by WEPP were 0.47,0.03,and-5.9,respectively.Nash - Sutcliffe model efficiencies of event soil loss simulation were 0.58,0.72,and 0.60,respectively.It indicated that event simulation result of soil loss was better than event simulation result of run-off.WEPP model was sensitive to the change of slope.Nash - Sutcliffe model efficiencies of event runoff simulation to soybean,Dallis grass,alfalfa,and elm were 0.81,0.71,0.83,and 0.94,whereas Nash-Sut-cliffe model efficiencies of event soil loss simulation were 0.81,0.71,0.83 and 0.94,respectively.This show that simulation results of alfalfa and soybean were better,compared with simulation results of grass and elm and simulation results of bare land on different slopes.From the above results,WEPP can be used to simulate event runoff and soil loss under different soil and water conservation measures and event soil loss at different slope gradients on bare land,but it is not suitable to simulate event runoff at different slope gradients on bare land.

Abstract:In order to make the division of geological disaster susceptibility in Yaozhou District of Tongchuan City,4 most representative townships were chosen and the main influence factors to geological disaster susceptibility were determined.The factors were types of rock and soil mass,physiognomy,annual rainfall,and human engineering activity strength,which were verified using fractal and fractal dimension theory.The relational degrees between each influence factor and susceptibility obtained by the grey relational analysis were taken as the evaluation weights of the MAPGIS spatial analysis.By superposition of different layers,the regionalization map of geological disaster susceptibility was finally completed.Result showed in the map was basically consistent with real situation.

Abstract:Slope protection components made of sandy soil,cement,and a stabilizer named SY were investigated.Unconfined compressive strength and freeze-thaw cycle tests were carried out by samples with maximum dry density.Results present that all the engineering properties of the stabilized soil samples are improved significantly and SY stabilizer,cement,and sandy soil have coordination.From SEM pictures and mechanism analyzes,it can be proved that for sandy soil which has more pores in micro-structure,AFt Crystals,SiO2 gel,and C-S-H gel fill pores well,which makes the micro-structure denser and the expansion of AFt Crystals.They all benefit macro-engineering properties of stabilized sandy soil.SY solidified soil components satisfy the quality requirements in slope protection engineering and have high economic,social,and ecological values.

Abstract:Through secondary development of estimating average rainfall in artificial precipitation operation regions,the rainfall distribution of different attribute precipitations by various interpolation algorithms and the rainfall distribution in different grid intervals by the same interpolation algorithm were studied using interpolation algorithms of Surfer 8.Results showed that the first selected interpolation algorithm for rainfall amount of convectional precipitation was radial basic function method and for mixed precipitation,the least curvature method was best.The interpolation grid intervals for the rainfall distribution of convectional and mixed precipitation were 0.1° ×0.1°.The estimated value of average regional rainfall by inverse distance square method was unaffected by grid interval,markedly lower than that by arithmetic mean method.For convectional precipitation,when the gridinterval was0.1° × 0.1° or even smaller,the estimatedvalues by other four kinds of interpolation algorithms were lower than that by arithmetic mean method,while for mixed precipitation,the valueswere basically unaffected by grid intervals and equivalent to that by arithmetic mean method.

Abstract:Riparian zone,an ecotone between land and river,is an important component of a river.It is also very significant to human’ s production and livelihood.Based on a variety of domestic and foreign evaluation systems and combined with the water characteristics and field instigation of the Andamu River,16 indicators are selected for the naturalness evaluation index system that matches both in structure and functions by using the methods of hierarchical analysis and vague integrated appraisal.Under the comprehensive consideration of the geological features and community characteristics of a balanced riparian ecosystem,the nearnatural levels of a riparian zone can be classified into four grades:natural state,nearnatural state,degrading state,and degraded state.The evaluation results of the Andamu River by using the naturalness evaluation index system match the actual conditions.The naturalness evaluation index system may be applied as a suitable evaluation system for the riparian zones in Beijing sunburn.

Abstract:The Three Gorges Reservoir area is prone to the occurrence of geohazards.Reservoir impoundment will reduce slope stability and result in the active geohazards,such as landslides and rockfalls.The future geohazard activities in the area after reservoir impoundment can be divided into following stages:increasing stage,intensive stage,decreasing stage,and quasi stable stage.The harmfulness is not only related to the size,location,and activity of geohazard body,but also to the importance,damage pattern,and treatment difficulty of the affected objects.Surges in the reservoir trigged by large landslides and rockfalls may cause severe second hazards in the bank area.Based on the activity tendency,damage characteristics,affected object importance of geohazards in the facing slope zone to the reservoir and by considering the uncertainties of understanding geohazards and the social and economic development level in the area,a mitigation principle of “taking actions that suit affected objects,giving first place to avoidance and second place to engineering work,”and the related measures to the principle are proposed.

Abstract:The models evaluating the benefits of runoff and sediment reductions by single soil and water conservation measure under the configuration conditions of different control measures are constructed based on more than 40 years’ observation data in major hydrology stations in different regions,coupling the observation results of soil loss under different soil and water conservation measures for different hydrological year types in the regions with large quantity of sediment on the loess plateau.Using modern information technology,an evaluation system is established to estimate the benefits of runoff and sediment reductions by soil and water conservation measures on the loess plateau.The system can be applied to evaluate the benefits of run-off and sediment reductions by soil and water conservation measures for different hydrological year types in a quantitative way and provide a scientific basis and the decision support for soil and water conservation and the construction of eco2environment on the loess plateau.

Abstract:Ecological city is the development direction of future city.Qinhuangdao City is regionalized in order to enforce ecological city construction preferably and achieve the sustainable development of regional economy.By making use of 3S technology and combining ecological function regionalization with the main function regionalization,the city is divided into 3 main function regions,7 ecological subregions,and 29 ecological function regions.The regionalization work is based on the assessment of ecological environment and the integration of the regional resource distribution with social economical development indicators.The main ecological function and development direction are put forward for every function region.At last,the feasible advises are put forth in order to realize ecological function regionalization.

Abstract:Experiment was conducted to study the effects of Bromus riparius on soil and water conservation on the slope with calcareous cinnamon soil in Beijing by analyzing the relation to main biological characters and soil and water loss for a year.Bromus riparius turned green in April and its cover was over 85% in July.In August,their overground and underground biomasses at the highest plant density were 2 322.6 and 5 623.0 kg/hm²,respectively,and the root amount in 0? 10 cm soil layer was important to prevent soil and water loss.T he main form of soil erosion on the slope with the calcareous cinnamon soil in Beijing was surface runoff.Rainfall and biological characters were two major factors to soil erosion on the slope.T he order of factors was surface runoff> rainfall> rainfall intensity> slope degree> vegetation cover> vegetation height> tiller density according to their effects to soil erosion.After one year Bromus rip arius,the physical properties of the calcareous cinnamon soil were significantly improved.Soil bulk density was deduced by 2.4% ~ 9.8%,soil compaction was decreased,and infiltration capacity was promoted.T he yearly amount of surface runoff loss and soil erosion modulus on the slope were reduced to 13.5 mm and 105.2 t/(km²? a) and the capacity of soil and water conservation reached 65.4 % and 98.1%,respectively.Grass planting on the slope with the calcareous cinnamon soil has great significance in soil and water conservation.

Abstract:The project of converting slope farmland into forest and grassland has greatly influenced evolutionary trend in the agricultural eco2economic system of Wuqi County.The income structure of crop farming:animal husbandry∶parergon∶forestry changed from 31.5∶7∶10.5∶1 in 1990 to 3.4∶3.2∶3.4∶1 in 2006.The landuse structure of cultivated land ∶forest land ∶artificial grassland evolved from 1∶2∶5 in 1999 to 1∶14∶10 in 2006.Based on the above result,the 8 indexes of population,crop farming income,forestry income,animal husbandry income,industry income,per capita net income,yield of grain,and forest coverage were chosen.Cluster analysis method was used for the discussion on the evolvement stage of agricultural eco2economic system of Wuqi County.Results show that 1990 - 1996 was the incipient stage of the second stage ; 1997 - 2002 was the mid2latter of the second stage ; and 2003 - 2006 was the initial stage of the third stage.In view of the existing problems,it is necessary to adjust forest structure,develop forest (grass)and related industries,train labor service,and increase labor output for the purposes of promoting the sound interaction in the agricultural eco2economic system and realizing agricultural resources and industrial optimization coupling.

Abstract:The landuse information was extracted from the remotely sensed imagery in the years of 1986,1997,and 2006,automatically.Based on the thematic maps,the quantitative change over last 20 years was analyzed.At the same time,the indexes of the relative rationality of the landuse structure,mean patch area,patch particle fraction structure,and patch area standard deviation were used to analyze and evaluate the patch changes of the cropland,grassland,and forest.Analyses indicate that (1) cropland has decreased since 1986 and the decreased range was larger during the period from 1997 to 2006.On the other hand,grassland,forest,residence,and industry increased and the change range was larger from 1997 to 2006.(2) Landuse structure was improved,but the general pattern did not change.More cropland was distributed on the slope greater than 25 degrees.(3) The cropland fragmentation was continuously rising and its distribution was more dispersed.Otherwise,the distribution of grassland was more concentrated and more continuous.The small and middle patch numbers of forest largely increased,which resulted in the more obvious difference in the patch quantity structure.

Abstract:By field survey and follow-up investigation on famers,the technology on the comprehensive management in Wuguan small watershed in the lower reaches of Jinsha River is studied,including biological measures,engineering measures,farming practices,and other complementary measures.The ecological,economic and social benefits are further analyzed.Results showed that forest and grass coverage rate was improved from 25% to 81%,an increasing of 56% ; the average annual amount of soil erosion was reduced from 26 700 to 6 500 ton,a decreasing of 75.77% ; grain yield was increased from 3 645 to 9 330 kg/hm²,an increasing of 156% ; per capita food production was increased from 282 to 416 kg,an increasing of 47.52% ;agricultural output value was increased from 4.15 @ 10⁵to 4.40 @ 10⁶thousand yuan,an increasing of 960.13% ; and per capita net income was increased from 184 to 1 660 yuan,an increasing of 802.17%.In the end,the paper summarized the successful experience of the comprehensive control in Wuguan small water-shed and the referenced significance to other small watersheds in the Jinsha River region.

Abstract:Road construction brings social and economical benefits,but meanwhile seriously destroys the structure and disturbs the functions of ecosystem.Thus it becomes a threat to ecosystem health.The ecological effects of road construction are analyzed in terms of the components,structure,and functions of ecosystem,which appears a cascade response process.The method used to analyze such ecological effects is mechanism discussing.The variability of ecosystem structure in space and time scales under the disturbance of road construction is discussed,such as the changes of hydrology pattern,vegetation succession,and wildlife distributing structures.Road construction also disturbs the continuity of the process of ecosystem cycle,energy flow,and information transmission.Ecological measures to mitigate the ecological effects during the programming,constructing,and running period are raised,which involve ecological programming,ecological restoration,and ecological compensating.The ecological theories and methods are used to guide the construction of roads in order to find a way of harmony development among social,economic,and ecological benefits and eventually achieve sustainable development.

Abstract:In order to investigate the effects of farming and anthropogenic activities on underground river during fertilization period in karst area,we collected 102 water samples in the upriver,downriver,and paddy fields of Qingmuguan underground river in Chongqing in May,2008.According to the ions change in the upriver,downriver,and paddy fields of the underground river in the monitoring period and the molar ratios of Na⁺,SO^2-₄,NO^-₃ to Cl^-,the water quality in the upper and lower reaches of the underground river is closely related to agricultural and industrial activities and SO^2-₄,NO^-₃ and Cl^-in the underground river respond well to the fertilization activity.The springs in the downriver are the main water resource of living and production for local residents,so,study of the water quality in the period may have a certain role and significance in the guidance of water security.

Abstract:Most of cities in China have developed with a high speed since 1980s and more and more groundwater resources are over-pumped every year.Because 60 %of water sources are groundwater in Tai' an City,the degradation of the city' s groundwater environment occurs with the high-speed development,including degradation of groundwater dynamic force field,groundwater pollution,and geological hazards.Research results show that there is a significant correlation between city' s high-speed development indexes and groundwater environment degradation indexes.Meanwhile,the fitting curve and fitting function also indicate that there are some obviously driving actions to the degradation of groundwater environment caused by city' s high-speed development.

Abstract:In order to deeply grasp households'awareness and attitude toward the grain for green policy,we investigate more than 100 households of Yangjiagou Township,Mizhi County,Shaanxi Province and then seriously deal with questionnaire with the help of Spss software tool.Analysis indicates that about 97.17 %households have a positive attitude toward the Grain for Green Policy and however,they do not really understand its aim according to our inquiry.Through correlation analysis,we find that it is farmers' age,knowledge level,the area of returning cultivated land,family size,the number of labor force,the area of cultivated land,economic income,etc.that significantly affect households'awareness and attitude toward Grain for Green Policy.The former 3 factors are the ones that influence more dominantly those families whose income is mainly from crop and domestic animal,while the economic income exerts more impact on those families who make money mainly by their labor forces.

Abstract:Through investigation and interviews,the interaction between household types and agricultural types in Gaoxigou Village,Mizhi County,Shaanxi Province is explored by using the multi-correspondence analysis(MCA) and hierarchical clustering analysis( HCA).Analyses show that(1)there are close relationships between household types and agriculture landscape change types.( 2)The combination of the HCA and MCA is helpful to reveal the interaction mechanisms between household land use behavior and landscape type change.( 3)This article determines the main household type that influences the landscape change in the area and provides a basis for regulating landuse behavior of households.

Abstract:Based on landscape pattern data in 1986 and 2000,terrain gradient characteristics of landscape pattern change in Guyuan County in the upper reaches of Jinghe River were quantitatively analyzed and discussed by using terrain niche index and transformation probability among the landscape types.Results showed that the whole landscape spatial pattern along terrain gradient was subject to little change during the late 20th century.Grassland and forest mainly occupied high terrain niches and other landscape types occupied low terrain niches.Meanwhile,there was regular variation in their distribution index values in different terrain niche zones because of the conversion and competition among the landscape types to a certain extent.The dominance degree of construction land on low terrain niches increased and the dominance degree of farmland decreased reversely,while the dominance degree of grassland on high terrain niches ascended and the dominance degree of forest descended correspondingly.Conclusively,human' s reconstruction on landscape patterns in Guyuan County focuses on low terrain niche areas so that the effects are not obvious and the unreasonable landscape structure being formed previously does not change significantly.

Abstract:Debris flow can be divided into three types according to its outbreak frequency:high-frequency( one or many times in a year),medium-frequency(one time in several to 30 years),and low-frequency(one time in more than 30 years).Low-frequency debris flow often burst fiercely without any anticipation and cause serious harm.Based on the analysis of the data from debris flow gullies with different outbreak frequencies,the characteristics of low-frequency debris flow are summarized.Watersheds with Low-frequency debris flow are characterized by high vegetation coverage and a small number and small-scale of adverse geological phenomena.The groove bed scour of low-frequency debris flow is dominant and erosion rate and sediment transport capacity are high.Understanding the characteristics of low-frequency debris flow has important significance in guiding debris flow prevention.

Abstract:The assessment of ecological risk is currently one of the foremost leading subjects in academic community.The feature of ingredient landscape characteristics is the information easily preserved.In virtue of landscape structure and its dynamic change feature,it can display the comprehensive trend and distributional scope for ecological impacts.This research,based on constituting comprehensive index in ecological risk assessment and utilizing spatial analysis of GIS,assesses the spatial features of ecological risk in Shandong Province.It show s that the mean ecological risking index in Shandong Province is 0.36,which implies that it belongs to mid-degree risk type.Within all risk types,fairly low risk type is the most common one.From the viewpoint of landuse type,the regions under construction and people' s living have high ecological risk and on the contrary,the ecological risk of forestry land is correspondingly the lowest.Finally,the measurements against the ecological risk are presented.

Abstract:Soil erosion in the Libo World Natural Heritage has different strength classes and partly accompanies rocky desertification.Based on GIS and RS technologies,the article analyzes the spatial distribution and features of soil erosion and probes its driving forces.The area is mainly controlled by factors like ecological environment,soil materials,soil erodibility,environmental heterogeneity,and the historical relationship between human and land.The study provides a reference basis for integrated soil loss control,reasonable soil utilization,and local industrial structure adjustment and is helpful to ecological environment protection and sustainable development in the Libo World Natural Heritage.