Abstract:Change of soil organic carbon under no-tillage paddy—upland rotation was studied through filed investigation and laboratory analysis.Results showed that with the increasing years of no-tillage,the maximum soil organic carbon occurred 5 to 6 years after water-cultivation and dry-cultivation.The content of soil organic carbon under no-tillage was significantly different from that under conventional tillage.The content of soil organic carbon within 5 cm of the surface soil was obviously higher than that in other soil layers,suggesting a certain surface accumulation phenomenon.The ontent of fulvic acid was found to be higher than the content of humic acid after water-cultivation and dry-cultivation.Ratios of soil carbon to nitrogen were from 10 to 16,which is favorable to nutrient release during organic matter decomposition.Change in organic carbon density was the same as that in soil organic carbon.The study may clarify the effect of no-tillage practices on the content of soil organic carbon and provide a theoretical basis for building a reasonable crop rotation model and a scientific guidance for promoting the use of farming methods.

Abstract:The relations of erosion and sediment yield with their impact factors on the Loess Plateau of China have been a research focus.A relation model based on BP neural network model is constructed by taking 23 small watersheds on the Northern Shaanxi Loess Plateau as test areas.In the relation model,six impact factors are selected as input variables and erosion and sediment yield modulus,as output variable.The weighted matrix is employed to express the interface for input variables and hidden layers and the interface for hidden layers and output variable.Results show that the model can effectively distinguish the correlativity between the six impact factors and erosion—sediment yield modulus.From strong to weak,the six impact factors can be ordered as: soil anti-erodibilitynibble degreegully densityaverage annual precipitationNDVIthe ratio of silt to clay.Finally,the validity of the relation mode is verified by randomly selecting 3 small watersheds and employing BP neural network model.This study may be helpful to improve the methodology of the analyses of erosion and sediment yield in a watershed.

Abstract:In order to study the impacts and hazards of debris flow disaster on the Linzhi—Jiacha section along the Yarlung Zangbo River in Tibet,remote sensing and geographical information systems techniques are used to extract information on the material sources in the debris flow origin areas along the Linzhi—Jiacha section and analyze the distribution characteristics of the material sources.Results from the study showed that the distribution of the material sources in the debris flow origin areas is not uniform due to the influences of formation lithology,altitude,and topographic slope.After glacier melting and glacier type mudflow,the material sources are more developed and the accumulated loose materials are more abundant,which further stimulates the material sources and produces a large amount of new material sources in the debris flow origin areas.Consequently,the frequency of debris flows along the river is raised and the scale of the debris flows is enlarged.

Abstract:Water retention and supply for four types of vegetation in Gangcha County were analyzed through the determination of soil physical properties and soil water characteristic curve.Results indicate that soil water characteristic curves for four types of vegetation are well in accordance with Van Genuchten model and the values of R2 are greater than 0.99,which indicate that Van Genuchten model may exactly describe the relationship between quantity and energy of soil moisture.The contents of physical clay are in the decreasing order of rape landtall grass landgrass and bush land;soil bulk densities,tall grass landgrass and bush landrape land;and soil total porosities,rape landgrass and bush landtall grass land.The result shows that soil physical properties for rape land are better than those for other two lands.Soil water retention increases with the increased soil suction and presents a trend of abrupt decrease in first stage to gentle change in latter stage.Soil water retentions for different vegetation types are in the decreasing order of tall grass landgrass and bush landrape land.Soil water retention can be effectively enhanced with the practices that improve soil physical properties by improving soil structure,increasing soil bulk density and reducing soil total porosity.Soil water supply decreases gradually with increased soil suction.Soil water supply at low soil suction for dense grass and bush land and tall grass land is obviously better than that for rape land and thin grass and bush land,while soil water supply at high soil suction for dense grass and bush land and rape land is obviously better than that for tall grass land and thin grass and bush land.These show that the vegetation on tall grass land and thin grass and bush land is easily threatened by drought.

Abstract:Temporal and spatial changes of monthly/annual precipitation in the upper reaches of the Hanjiang River were analyzed by using empirical orthogonal function,moving average,and linear regression analysis.Results showed that annual precipitation manifested a decreasing trend during the last 50 years on the whole.Monthly precipitation varied with a major decrease in April and September,but a slight increase in June and August.A major climatic shift occurred in the upper reaches of the Hanjiang River from 1980 to 1988.The shift caused a change in atmospheric circulation pattern with a decreased intensity of southwest monsoon in spring and autumn and an increased intensity of southeast monsoon in summer.Southwest monsoon could induce rainstorms and floods from June to early-middle July and in September.In the periods,reduction in precipitation possibly caused a reduction in the occurrence of flood.Southeast monsoon could cause rainstorms and floods in the late July and August,in which the enhanced monsoon possibly cause an increase in the occurrence of rainstorm and flood.These findings are of great importance in water resources and energy development and flood mitigation in the upper reaches of the Hanjiang River.

Abstract:Genesis properties and taxonomic classification in different types of topography and under different degrees of vegetation coverage are studied through the investigation of a 2 500 hm² unused land and the analysis of soil samples at different depths in the Bandengtan resettlement area of Dingbian County,Shaanxi Province.In the study area,soil genesis layers are not complete,and profile differences in soil color,soil structure,and soil nutrients are not distinct.Soil organic matter content is rather low,with a maximum content of 1.787 1 g/kg and a minimum content of 0.201 7 g/kg.There are no distinct eluviation and deposition of soil calcium carbonate and no distinct deposition layer in the profile.Sand(2~0.02 mm) is the main particle composition.The CEC concentrates at 2.5~5 cmol/kg,indicating a poor soil fertility.From the diagnostic horizons and their characteristics analysis,soils in the area belongs to 1 soil order,1 suborder,2 groups,and 4 subgroups,in which Ⅱ₁ belongs to Parasalic Aqui-Sandic Primosols;Ⅱ₅,Sodic Aqui-Sandic Primosols;Ⅲ₄,Calcaric Aqui-Sandic Primosols;and Ⅵ₄,Calcaric Usti-Sandic Primosols.The results can be used as a reference to comprehensive soil resources evaluation,soil suitability evaluation,and the rational layout of agriculture,forestry, and animal husbandry.

Abstract:An orthogonal experiment was conducted to investigate the effects of different concentrations of Ni²⁺,Cu²⁺,and Co²⁺,as well as different temperatures and light combinations,on seed germination features of Peganum harmala L and provide a basis for vegetation rehabilitation and ecological restoration in tail mining area.Results showed that low concentration of Ni²⁺,Cu²⁺,and Co²⁺ mixture solution was helpful to improve the Peganum harmala L germination potential,germination rate,and germination index and high concentration of the mixture solution showed significant inhibition.Peganum harmala L seedling growth was influenced by heavy metal ions concentration in the mixture solution in different extent,no matter the concentration was high or low.However,inhibiting effect of low concentration was not significant.In the treatment with 5 mg/L Ni²⁺,800 mg/L Cu²⁺,400 mg/L Co²⁺,25 ℃ temperature,and 12 h illumination,Peganum harmala L seeds germinated fast and germination rate was relatively high.Compared with different conditions,the optimum condition for Peganum harmala L seedling growth was found to be 100 mg/L Ni²⁺,100 mg/L Cu²⁺,50 mg/L Co²⁺,25 ℃ temperature,and 12 h illumination.

Abstract:The effects of different fertilizations on the content,distribution,and stability of soil aggregates were studied by a long-term fertilization experiment in a greenhouse soil.Results showed that the greatest size of wet stable aggregates of the greenhouse soil with organic fertilizer was in the 0.125~0.25 mm fraction,while the greatest size of wet stable aggregates of the greenhouse soil without organic manure was in the 0.053~0.125 mm fraction.The content of wet stable aggregates in 0.25 mm fraction was significantly lower than that in the 0.25 mm fraction.In the 0.125 mm fraction,the contents of wet stable aggregates with organic fertilization(AN0) and the combined organic and inorganic fertilization(ANPK) were higher than those with(BNPK) and without(BN0) inorganic fertilizer.The long-term application of organic fertilizer could enhance the formation of wet stable aggregates from macro-aggregates to micro-aggregates.The stability index of soil aggregates in different treatments was in the order of ANPK BNPK AN0 BN0.Fractal dimension(D),geometric mean diameter(GMD),and mean weight diameter(MWD) were all suitable to evaluating wet stable aggregates of the greenhouse soil.

Abstract:By taking the composite of the roots of Sabina vulgaris and soil around the roots as a research object,the effects of different root diameter classes and root layouts on shear performance of the root-soil composite were investigated through laboratory shear tests.Results showed that under different normal stresses,shear strength for the root—soil composite with roots was significantly greater than that for the disturbed soil without root.As for the root—soil composite,shear strength contributed by vertical roots was greater than that by horizontal roots.Under the condition of the same number of roots contained,shear strength for the composite was not proportional to the size of root diameter,but presented an increasing—fallback—rebounding trend with the increased root diameter.The study may provide some technical parameters and a theoretical support for the future plantation of Sabina vulgaris as a soil and water conservation measure.

Abstract:The effects of different treatments on Cupressus chengiana seedling growth were studied by a pot experiment with 2 N-fertilizer levels and 4 moisture gradients.Results showed that at the 15% and 25% moisture gradients,N-fertilizer restrained the height of seedlings and low N-fertilizer level had more significant influence;at the 5% moisture gradient,low N-fertilizer level slightly reduced the height and however,high N-fertilize level slightly increased the height;and at the 30% moisture gradient,the height increased with the increased quantity of N-fertilizer.At all the moisture gradients,N-fertilizer significantly increased the basal diameter of seedlings and high N-fertilizer level had more significant influence.N-fertilizer reduced the the height-diameter ratio of seedlings;at the 5% and 15% moisture gradients,high N-fertilizer level had more significant influence;and at the 25% and 30% moisture gradients,low N-fertilizer level had more significant influence.High N-fertilizer level reduced the root-shoot ratio of seedlings at all the moisture gradients;low N-fertilizer level reduced the ratio at the 5% and 30% moisture gradients,while increased the ratio at the 15% and 25% moisture gradients.At the 5% moisture gradient,N-fertilizer slightly increased the quality index of seedlings and the low N-fertilizer level had more significant influence;at the 15% moisture gradient,low N-fertilizer level slightly increased the index and high N-fertilizer level slightly reduced the index;and at the 25%,30% moisture gradients,the index increased with increased quantity of N-fertilizer.

Abstract:The effects of farmland management on soil physicochemical properties in an inland saline-alkali land were studied through household survey and indoor experiment.Results showed that there were the five crop planting modes of wheat—maize rotation,wheat—cotton rotation,melon—cotton interplant,maize—soybean interplant,and spring maize monoculture.The average contents of soil organic manure,alkali-hydrolyzable nitrogen,available phosphorus,and available potassium under the five planting modes were 20.1,60.1,106.2,and 170.2 mg/kg,respectively.The differences between the planting modes were significant and the soil nutrient contents were the highest under the melon—cotton interplant mode.Under the different planting modes,the highest content of soil alkali-hydrolyzable nitrogen was only 70.2 mg/kg,which suggests that nitrogen fertilizer should be added;the average content of soil available phosphorus was 15 mg/kg higher than what the plants need,which implies that phosphorus fertilizer should be reduced;and the average content of available K was 170.2 mg/kg,which implies that K fertilizer should be controlled according to the needs of crops.

Abstract:Taking Dongguan City as the study area and applying satellite images of the Landsat TM/ETM+ in five different times,authors discussed characteristics of land use changes in the three aspects of the quantitative change,centric migration,and spatial differentiation of land uses and analyzed its driving factors from natural and human perspectives.Results from the study showed that(1) from 1988 to 2005,the overall land use change was the greatly decreased farmland and rapidly expanded urban land;(2) gravity centers of all the land uses moved far away and centric migration of farmlands was basically opposite to that of urban land;(3) spatial autocorrelation for farmlands was deceased and that for urban lands was enhanced;(4) economic development and population growth were the main driving factors for land use changes in the study area and land uses in the area with low altitude and gentle slope changed more rapidly because of topographical conditions.

Abstract:Level terracing is a common forestation practice in the semiarid hilly-gully area of the Loess Plateau in China.To study the impacts of the practice on artificial forests,soil moisture and nutrient condition in a 20-year-old dense artificial Pinus tabulaeformis forest was evaluated.The average soil moisture content at the end of rainy season was found to be 6.94% in the 0—60 cm layer and 4.53% in the 60—160 cm layer,while it was 5.43% in the whole soil profile(0—160 cm).This indicates that the soil moisture level is not replenished significantly during rainy season.Alkali solution N,available P and K,organic matter,and total N were significantly concentrated within 10 cm of soil surface,while total P and K showed insignificant surface accumulation.The pH values at all sites were higher than 8.The average contents of total P and K and available P and K in the 0—100 cm layer were all in middle level,but the average contents of organic matter,total N,and alkali-solution N were low or very low.Result from the study suggests that in the semiarid Loess Plateau with insufficient precipitation,dense artificial forest may lead to soil moisture and nutrient condition deteriorating and that artificial thinning is an important work in later stage management of artificial forests.

Abstract:In order to investigate the photosynthetic characteristics of Onobrychis viciaefolia seedlings and the main environmental factors directly influencing photosynthesis of the seedlings,the photosynthetic characteristics of Onobrychis viciaefolia seedlings and the diurnal variations of the factors were measured using Li-6400 photosynthesis system by a pot experiment.Meanwhile,the effects of the factors on photosynthetic rate(P_n) were analyzed using correlation analysis and stepwise multi-regression analysis.Results showed that the diurnal variation of the P_n presented a feature of single peak curve with its peak value appearing at 12:00 am,about 27.63 μmol/(m²·s).The daily average P_n over the observation time was calculated to be 22.33 μmol/(m²·s).Besides,according to correlation analysis,photosynthetically active radiation(PAR) was found to be the main environmental factor directly influencing the daily P_n of Onobrychis viciaefolia seedlings and the PAR had a highly significant positive correlation with the P_n.

Abstract:By taking Caijiachuan watershed on the Loess Plateau of Western Shanxi Province,as the study object,the relationship between rainfall and runoff and the water balance in the experimental watershed were studied using statistical methods such as multiple comparison and regression analysis for the data of precipitation and runoff measured in the watershed from 2004 to 2009.Results showed that the percentage of yearly water consumption was 90% more than yearly rainfall.Water consumption appeared to be the main water output in the water cycle of the experimental watershed.The yearly runoff coefficient ranged only from 1.6% to 2.66%.Runoff and peak discharge for a single rainfall event changed evidently with changes in the magnitude order of rainfall amount(P) and the maximum 60-min rainfall intensity(I₆₀) in a jump mode.Specifically,runoff volume and peak discharge for P≥30 mm rainfall were about 8.31 and 6.52 times of those for the 0~10 mm order of rainfall amount,respectively.Runoff volume and peak discharge for I₆₀≥20 mm/h rainfall intensity were about 3.35 and 16.87 times of those for the 0~10 mm/h order of rainfall intensity,respectively.Regression analysis of runoff,peak discharge,and rainfall indexes under different types of rainfall showed that the contribution of rainfall intensity to peak discharge was highest(47.12%) under A-type rainfall(stom events with short duration and high intensity) as compared to that under B-type rainfall(storm events with long duration and high intensity,44.62%) and C-type rainfall(storm events with long duration and low intensity,32.51%),while the contribution of rainfall amount to runoff was highest(28.5%) under C-type rainfall as compared to that under A-type rainfall(26.69%) and B-type rainfall(3.15%).

Abstract:In order to investigate soil erosion processes for the Eucalyptus grandis×E.urophylla industrial plantations and other land use types,a comparative study of the characteristics of runoff and sediment yields from various slopes was made by runoff plot experiment.Results showed that E.grandis×E.urophylla plantations could better adjust runoff and reduce soil erosion.Among the three land use types investigated,runoff yielded from grassland was the most,which was 1.1 times of that from shrubland and 1.9 times of that from the E.grandis×E.urophylla plantations.Land uses,in terms of runoff yield,ranked in the descending order of grassland,shrubland,and E.grandis×E.urophylla plantations.Runoff yield between the E.plantations and grassland was very significantly different,while runoff yield between E.grandis×E.urophylla plantations and shrubland,significantly different.However,sediment yielded from shrubland was the highest,which was 1.3 times of that from grassland and 2.9 times of that from E.grandis plantations.Land uses,in terms of sediment yield,was in the descending order of shrubland,grassland,and E.grandis×E.urophylla plantations.There was very significant difference in sediment yield between the E.grandis×E.urophylla plantations and shrubland and significant difference in sediment yield between the E.grandis×E.urophylla plantations and grassland.Runoff yield from E.grandis×E.urophylla plantations was 47.83% less than that from grassland and sediment yield,55.90% less.There was no linear relation between runoff yield and sediment yield from different land use types.The results from the study provide not only more scientific and objective assessments for the relationship between runoff yield and sediment yield from E.grandis×E.urophylla plantations and the benefits of soil and water conservation,but also a theoretical basis and scientific evidences for its sustainable management.

Abstract:The variation of time sequence for cultivated land resources in Fuyang City are analyzed based on the statistical data of socioeconomic development and cultivated land conversion in 1995—2008.Meanwhile,the driving factors of cultivated land conversion are studied by applying general grey correlation analysis method.Results show that agricultural development is the basis and premise of cultivated land conversion.Population growth or urbanization level rises are closely correlated with the relative speed of cultivated land conversion.The effects of economic gross growth and industrial structure adjustment on cultivated land conversion are contributed by the driving force resulted from the intrinsic aims of itself economic development.The main factors such as government benefits promotion,investment craze,real estate craze,and export oriented economic trend play a minor role in cultivated land conversion in Fuyang City,though they accelerate cultivated land conversion in many large cities.

Abstract:Different tillage measures of soil and water conservation,such as ridge tillage,subsoiling,cross-slope cultivation,and no-tillage seeding,are taken to control serious soil erosion on sloping farmland in the arid areas of Northern China.In 2010,the effects of different conservation tillage measures on surface runoff,soil erosion,and rainfall infiltration were studied on a 5° farmland in Dongxing Village,Qiqihar City,Heilongjiang Province.Results showed that all the conservation tillage measures had a certain effect on the reduction in runoff and soil erosion.Cross-slope tillage had the most obvious effect,with which surface runoff and soil erosion were reduced by 92% and 90%,respectively,and stable infiltration rate was increased by 41.2% as contrasted with conventional tillage.Changes in runoff coefficient,sediment concentration in runoff,runoff generation,and sediment yield under the different conservation tillage measures were all consistent with the order of cross-slope no-tillage cross-slope cultivation subsoiling and ridge tillage ridge tillage less tillage and subsoiling no-tillage conventional tillage bare land.

Abstract:Based on the analysis of estimation methods for vegetation coverage at home and abroad,a technological route of model application is designed to estimate vegetation coverage in the upper reaches of Huaihe River.The study is conducted by using binary pixel model and "Beijing-1" micro-satellite multi-spectral data under consideration of the situation of the study area.Then the estimated results are validated and analyzed by using ocular method and photographic method.Results show that the model correlation coefficient is 0.818.The average vegetation coverage in the study area is 58.1% and presents a γ-type spatial distribution which is low in the north and high in the south.

Abstract:Based on the investigations of vegetation and soils,changes of vegetation recovery at different inter-belt distances and soil nutrients after different recovery years in a belt-type artificial forest of Aohan Banner,Chifeng City,Inner Mongolia are studied to reveal the promotion effects of belt-type sand fixation forest in the inter-belt vegetation recovery and soil development.Results show that(1) belt-type poplar plantation can significantly improve in inter-belt vegetation recovery and soil development.(2) Inter-belt distance can affect the effects of vegetation recovery and soil development.The recovery effect is in the order of 24 m inter-belt distance 18 m inter-belt distance 12 m inter-belt distance.(3) Difference of inter-belt distance has an important influence on niche breadth of species.(4) Gaussian model can be used to describe the effect of inter-belt vegetation recovery.According to the model,sand fixation forest belts can best promote inter-belt vegetation recovery if inter-belt distance is between 28 and 40 m.

Abstract:Through runoff plot experiment on slope,runoff,erosion and nutrient loss in Heibeishan watershed from May to August in 2009 and 2010 were studied.Results indicated that runoff,erosion,and nutrient loss from runoff plots under natural rainfall condition had a certain similarity.They were in the decreasing order of bare land,ridged-furrow,contour listing,film mulching,and equal-height deep loosening.Compared with the bare area,the conservation tillage could reduce runoff by 29.8%~63.3%,soil erosion by 64.6%~96.6%,nitrogen loss by 54.0%~89.5%,and total phosphorus loss by 49.4%~92.2%.This suggests that conservation tillage can play very good roles in conserving soil and water and reducing nutrient loss.

Abstract:Soil amelioration effects resulted from salt reduction by the three plantations of pure Robinia pseudoacacia,pure Populus liaoningensis,and mixed P.liaoningensis and R.pseudoacacia were studied in raised fields established by soil preparation engineering measures in saline-alkali soils along muddy seacoast of Northern China.Results showed that the three plantations were almost closed after 11 years.The reservation rates were 63%~72% and shade densities were 0.6~0.7.The height and DBH of the mixed plantation were higher than those of the two pure plantations.The desalination effects of the three planting patterns were observed within 70 cm of soil surface and soil nutrient deficiency was formed between 50 and 70 cm below soil surface.The mixed plantation increased soil organic matter content on the forest land.Within 100 cm of soil surface,the distribution rhythms of total N in soil profiles were similar to those of organic matter.The variation of the contents of total P in the three plantations was not significant.On the whole,the total amount of phosphorus was deficient and its efficiency was low.Factor analysis indicated that soil amelioration effects for the mixed plantations of P.liaoningensis and R.pseudoacacia were better than those of pure plantations,which could enhance the fertility status of saline-alkali soils along the muddy seacoast and might be applied in practice as a promising afforestation model.

Abstract:By taking small watershed on the 1∶10 000 scaled topographic map of Qingshuichuan basin in the coarse sand source area of the Loess Plateau as a basic cell,terrain factors for regional soil erosion,including surface relief,variance coefficient,and contour line density,are extracted from 1∶250 000 scaled digital elevation model.The terrain factors calculated from the 1∶10 000 scaled map are regarded as truth values to fit the calculation method of terrain factors for soil erosion in each region.Results showed that only the contour line density is an appropriate index of terrain factors for regional soil erosion.The method has been applied in the lower reaches of Huangpuchuan River,with the deviation less than 10%.Such a good simulation result indicates that the method can be used as a reference to index determination in the calculation of regional terrain factor for soil erosion.

Abstract:Based on the spatial landuse database of Pucheng County in Shaanxi Province,fractal dimension and stability of landuse types are studied by using GIS technology and fractal theory.The landuse is classified into 6 types: cropland,garden plot,woodland,grassland,industrial and residential areas,and other lands.The fractal dimension for the patches of the landuse types is analyzed.Results showed that all the landuse types have fractal characteristics and the fractal dimension(D) values vary from 1.344 to 1.522.In terms of the landuse stability given by the fractal dimension,the order of the landuse types from high to low is woodland,industrial and residential areas,other lands,cropland,grassland,and garden plot.Complicated geomorphic type is of importance to the fractal dimension of landuse type and the fractal dimension values may better indicate landuse structure and stability.Fractal dimension can be used as an effective index in the researches on landuse structure in Pucheng County.

Abstract:Soil samples were taken from Kelamayi to Elm Ditch along provincial road No.201 in Xinjiang Wei Autonomous Region and the main factors influencing the expansion characteristics of carbonate saline soil were studied through laboratory test.The effects of the natural vertical distribution of saline soil layers on the expansion of saline soil were discussed at first.The expansion ratio was found to vary with soil sampling depth and the expansion was most significant between 25 and 75 cm below soil surface.By taking seasonal variation and temperature variation into consideration,the characteristics of saline soil in freeze-thaw cycle studied and temperature was found to have little effect on the expansion characteristics of carbonate saline soil.Expansion test was made with specimens containing salt 0.5%,1.0%,1.5%,and 2.0% in weight to analyze how salt content affects the expansion characteristics of the soil.Results show that the maximum expansion ratio increased from 10.0% to 22.5% as salt content increased from 0.5% to 2.0%.

Abstract:Photosynthesis and water utilization efficiency of wild bitter bamboo(Pleioblastus amarus) were measured using portable photosynthetic analyzer LI-6400TX in order to provide a scientific basis for the management of Bitter Bamboo.Results showed that the curves for diurnal changes in net photosynthetic rate and stomatic conductance of Bitter Bamboo exhibited two peaks and the obvious phenomena of midday depression.Stomatic conductance had a significant linear relation with net photosynthetic rate.Stomatic conductance was found to be a key limiting factor for the photosynthesis of Bitter Bamboo and therefore,the midday depression was mainly regulated by the stomatic factor.Water utilization efficiency of Bitter Bamboo was relatively low,indicating that it is poor in water-saving and drought resistance.Light compensation point and light saturation point of Bitter Bamboo leaves were 8.10 and 1 198.66 μmol/(m²·s),respectively,indicating that Bitter Bamboo is a shade-tolerant species and can adapt to a wider lighting condition.

Abstract:Extracting river network characteristics based on digital elevation model(DEM) is a hotspot in digital hydrology research.By taking Binzhou River basin in the black soil region of Northeast China as an example and using 5-meter resolution DEM as the data for study,river network features were extracted by applying Arc Hydro Tools in ArcGIS 9.2 version.Results showed that when different drainage networks were extracted by setting drainage area threshold value to be 0.75,1.25,2,2.5,3.75,and 5 km²,respectively,different threshold values had very little effect on spatial position of the main stream network,but extracted river network features of the digital watershed changed greatly.A method for setting a suitable threshold value was proposed based on the relation of source density/drainage density with drainage area threshold.It was found that when drainage area threshold was 2 km²,extracted river network features were basically consistent with actual drainage net features,with prediction accuracy reaching 95%.Therefore,automatic extraction of watershed features based on Arc Hydro Tools is feasible.

Abstract:In order to estimate soil solidification performance of EN-1 solidifying agent,saturated hydraulic conductivities for four types of soils collected from Yangling,Ankang,Ansai,and Jingbian in Shaanxi Province were investigated by indoor simulation test with different solidifying agent contents and curing ages.Results indicated that traces of EN-1 solidifying agent added in the tests can considerably reduce saturated hydraulic conductivities of yellow brown soil and Lou soil.The saturated hydraulic conductivities decreased rapidly with the increased curing age and dropped to zero when curing age was more than 14 days.Saturated hydraulic conductivities of loessal soil and sandy soil decreased not only with the increased addition of the solidifying agent,but also with the increased curing age.The saturated hydraulic conductivities of loessal soil and sandy soil were the lowest at the 1% EN-1 solidifying agent after 28 days curing.

Abstract:In order to address the ecological fragility and economical backward in rocky desertification areas of Chongqing City,five varieties of Honeysuckle were introduced from He′nan Province,Shandong Province,Hu′nan Province,and Chongqing City for a comparative study.It follows from comparison,observation and analysis that due to germplasm and the geologic base system,both variety "Yu Lei 1" and variety "Meng Jin 1" were good in shoot and leaf growth and flower bud development,as well as in yield and quality.Especially,the yield of "Yu Lei 1" was as high as 2 070 kg/hm²,and the main drug ingredient chlorogenic acid and flavonoids of the genuine variety "Meng Jin 1" actually reached 7.39% and 3.04%,respectively.By comprehensive evaluation,both of the varieties are suitable for the promotion in the region.

Abstract:Large scale drought monitoring based on remote sensing plays an important role and however,only a few studies of the spatial adaptability about a variety of remote sensing drought indexes in different regions were conducted.Normalized difference vegetation index(NDVI),anomaly vegetation index(AVI),vegetation condition index(VCI),and temperature condition index(TCI) were separately calculated based on MODIS images of He′nan Province and its drought situation in the latest decade was analyzed in combination with traditional meteorological drought index.Results showed that droughts occurred at different extents in six years between 2000 and 2009 and the northern and western parts of He′nan Province were more prone to suffer from severe droughts.Result from remote sensing monitoring for drought was consistent with the meteorological drought index.After analyzing the correlation between remote sensing drought index and meteorological drought index in different periods and regions of He′nan Province,four indices were found to have spatiotemporal adaptability.The research provides a technological support for drought monitoring.

Abstract:Through the investigation of the vegetation restoration and soil properties on an artificial-repaired slope in Qingfeng quarry,the relationships among soil physicochemical properties,soil enzyme activities,and vegetation restoration on slope,as well as the dominant factors affecting soil quality were explored so as to provide a theoretical basis for rocky slope protection and eco-restoration.Results showed that with regard to species diversity,plant community structure,and its stability or soil quality,the artificial restoration slope did not rapidly reach the natural state in a short term.There existed different degree correlations among soil properties and the plant indexes of Margalef,Shannon—Wiener,and Pielou when the indexes were applied in the herb and woody layers on the vegetation restoration slope.Species diversity in herb layer had greater impacts on soil water content and the activities of acid phosphatase and protease,while species diversity in woody layer mainly affected total phosphorus and protease activity.Factors like soil available nutrients,soil enzyme activities,and soil organic matter were the dominant factors affecting soil quality.

Abstract:Based on the situation of agricultural eco-economy in Minqin County,select the period from 1994 to 2003,when Minqin County was typical in the damages to ecosystem in the region,using energy value method investigate and analyze the components and their indicators related to energy flow within the agro-ecosystems in that 10 years.In the period,the annual energy inputs in agricultural eco-economic system of the county was 1.51E +21 sej,of which contribution of environmental resources was only 22.47% and renewable environmental resources,only 15.00% of the total energy input,while industry supplemental energy in socio-economic inputs reached as high as 57.20% of the total energy.By comparative analysis,Minqin energy density was found to be in a lower level.In view of the environmental loading ratio(ELR),the agricultural ecosystem of Minqin County presented a typical characteristic of petrochemical agriculture in the Hexi region.In view of the energy-based sustainability index(ESI),the sustainability of the agricultural ecosystem development of Minqin County in the 10 years was not only poor,but also showed a declining trend year by year.

Abstract:This study aims at providing valuable references for soil and water conservation in the future through analyzing the comprehensive soil ad water loss control and evaluating its benefits in Jiangsu Province.By analyzing the characteristics and current situation of soil and water loss in Jiangsu Province,comprehensive control systems of hill,river,field,forest,and road for small watersheds in the hilly areas and river,ditch,embankment,fields wood,and road for small regions in the sandy plain areas have been established.The plans for key engineering measures distribution and their engineering amount in the areas are formulated.Based on the control systems,index system and the corresponding calculation model for the benefits evaluation of soil and water conservation were established to measure and analyze ecological,economical and social benefits of the planned measures.Results showed that all the control measures reduced soil erosion 1.384 6 million tons and water interception and storage 127.452 2 million cubic meters in the year when the measures became effective.Besides,50.590 5 million RMB economic benefits were turned out significantly at the final stage of plan implementation and farmers′ average per capital income increased by 552.18 RMB.

Abstract:Historically,many paleochannels formed along the current main stream of Tarim River due to frequent migrations.Research on the grain size characteristics in surface sediment of the paleochannels is helpful to determine the sedimentary environments and hydrodynamic conditions during the surface sediment formation.Through systematic samplings and grain size analysis for surface sediment of the paleochannels,we find that:(1) silt is the dominated grain fraction in surface sediment of paleochannels and the secondary grain composition is obviously different between the south and north paleochannels along the current main stream;(2) the grain size for surface sediment of the paleochannels is smaller than that for surface soils in the floodplain of Tarim River,which suggests that hydrodynamics was relatively weak in the late period of paleochannels formation;(3) there are eolian sand layers in surface sediment of some paleochannels on the south bank of Tarim River,which implies that the sedimentary environments were influenced concurrently by wind and water.

Abstract:River health has great influences on the rise and decline of human society.The assessment of river naturalness can easily tell us whether a river is healthy or not.By taking Tanghe River as an example,the river naturalness was assessed from geographic,ecological and hydrological aspects by using analytical hierarchy process(AHP).The naturalness assessment is made based on the division of the river channel by establishing a river naturalness assessment system composed of 22 qualitative and quantitative indicators.By the final assessment result,the naturalness can be classified as four grades: natural state,near-natural state,degraded state,and artificial state,which coincide with the result from clustering analysis.Analysis of the data indicates that Tanghe River is in the near-natural state on the whole,but some portions of the watershed have been seriously degraded.The naturalness assessment system established in the study may serve as a reference for the assessment of rivers in Beijing suburb and the result from the assessment may provide a basis for future ecological construction of Tanghe River.

Abstract:By taking the northern slope of Tianshan Mountains as the research object,water footprint in the area is calculated by using an improved method.Then the relationship between desertification and water footprint is established based on the analyses of the spatiotemporal variation of water footprint and the desertification patterns.Moreover,the processes and mechanisms of oasis and desertification on the northern slope of Tianshan Mountains are analyzed from the water footprint perspective.Results showed that(1) from 1960 to 2007,water footprint in the area tended to increase obviously and meanwhile,water footprint structure changed significantly;(2) the productive water footprint had obvious spatial variation for the cities and counties in the area;(3) there was a significantly negative correlation between the deserted area and water footprint on the northern slope of Tianshan Mountains;(4) the adjustments of regional production structure(especially agriculture) and the improvement of the regional people′s consumption patterns are favorable to reduce the pressures on water resources in arid areas,which have an important strategic implication for the early warning and prevention of desertification in arid areas.

Abstract:From the economic value perspective,economic values of water conservation function in the Qinling National Ecology Function Zone(QNEFZ) were estimated by using shadow project approach and market value method.From the estimation,the total water conservation value for the QNEFZ in 2010 was about 31.7 billion Yuan,being equivalent to the gross domestic product(GDP) of Ankang City and 5.7 billion Yuan higher than the GDP of Shangluo City.Water conservation value for the QNEFZ in 2010 was 8.8 billion Yuan more than that in 2002,about 1 billion Yuan increase per year,which indicates a significant improvement in water conservation function.However,the current economic value of water conservation function is just a potential value.In the future,it is important to establish the ecological compensation mechanisms to fit market economy for promoting the transformation of the potential value to real value.

Abstract:Guangxi Zhuang Autonomous Region is a typical subtropical karst region with severe rocky desertification in China.Based on the SPOT-VEGETATION images used as the main data source,the distribution of rocky desertification in Guangxi Province in 1998,2003,and 2007 is inversed by combining maximum value composites(MVC) method and dimidiate pixel model with geology,landform,and landuse map.Additionally,in FRAGSTATS platform,the evolutionary characteristics of rocky desertification in the 10 years are analyzed by selecting some landscape pattern indexes,such as Shannon Diversity Index(SHDI) and Contagion(CONTAG),and using spatial analysis method of landscape.Results from the research show that the overall landscape level of rocky desertification in the region was characterized by high inner homogeneity and low landscape heterogeneity.The total rocky desertification area decreased by 177 283 hm2,indicating a good effect of management.The change in light rocky desertification was most significant and the area for this type of rocky desertification is the important and prime objective of management.

Abstract:By taking 2007TM images and 1∶250 000contour maps of Bazhong City as data sources and using GIS spatial analysis functions,landuse database of Bazhong City is established and the DEM,slope,and terrain niche index chart are produced.Then,slope gradient,elevation gradient,and terrain gradient are respectively overlaid with landuse landscape data.The distribution characteristics of different landuse landscapes at different terrain gradients are discussed by introducing the dimensionless distribution index.Results showed that the forest land mainly distributes in the place with higher elevation,steeper slope,and greater terrain niche.Farmland and rural residential land are located in the place with low altitude,gentle slope,and low terrain niche due to the effects of climatic conditions and water distribution.Unused land is in the vast and distribution trends of the landuse landscapes.

Abstract:Water quality assessment plays an important role in water environmental protection and management.Traditional methods have some limitations in dealing with the uncertainty in assessment and massive information.A Bayesian network model can effectively express and analyze uncertain problems and combine qualitative analysis with quantitative analysis.Based on the mornitoring data for nearly ten years in Xiang-shan harbor of Ningbo City,a Bayesian network model expressing the relationships and interactions between different water quality indexes and water quality levels was constructed by Bayesian network approach.The model structure indicated that ammonia nitrogen,COD,inorganic phosphorus,nitrate,and chlorophyll had direct effects on water quality level,whereas there was an indirect causality between other water quality indexes such as nitrite and inorganic nitrogen and water quality level.The results of the model validation using 200 monitoring data showed that the predictive precision reached 94.8% and the Kappa was 0.892,which suggests the Bayesian network is feasible for assessment and prediction of water quality.

Abstract:Flood disaster is one of the world′s main natural disasters.The study of vulnerability assessment is greatly helpful to regional flood control.After considering natural conditions,socioeconomic situation,and disaster prevention/reduction measures in the 13 districts of Tianjin region,a flood vulnerability assessment index system was firstly established.In order to reduce the subjectivity in the assessing process,a combination idea was adopted to optimize traditional comprehensive assessment model and then assess the flood vulnerability in the region.Results from the assessment showed that Tianjin region was overall in a high level of flood vulnerability and vulnerabilities in different districts had significant difference.For all the assessment units,Tanggu,Hangu,Ninghe,and Dongli districts or counties in the eastern area of Tianjin region had the highest flood vulnerability.This conclusion may provide a theoretical support for Tianjin region to formulate economic development planning and carry on flood control works.

Abstract:To solve the over-fitting problem of Hopfield neural network,Hopfield neural network model with factor analysis was proposed based on factor analysis combined with Hopfield neural network model.Taking Dongliao River for an example,the model determined seven water quality evaluation factors using factor analysis method,created a 5×7 Hopfield neural network to evaluate water quality comprehensively,and compared the results from single Hopfield neural network and traditional Nemero Index method.Results showed that the factor analysis Hopfield neural network is much better than single Hopfield neural network.It not only makes up for the defect that factor analysis does not achieve the classification of water quality in practical applications,but also effectively reduces the extent of over-fitting of Hopfield neural network.The evaluation results are more reasonable and the model provides a new approach to comprehensive water quality evaluation with some excellent prospects.

Abstract:Land use/coverage characteristics and diversity indexes under different elevations,slopes,aspects and relief amplitudes in Danjiang River basin of Shaanxi Province were studied using RS and GIS techniques through the format conversion and identity between vector data and grid data.Results indicated that in Danjiang River basin,grassland was dominated in all the landuse types.The distributions of landuse types except water surface presented significant peaks with increased elevation.The areal proportion for cropland,forest,and grassland at the elevations from 800 to 1 200 m was the largest;the areal proportion of landuse types on 15°~25° slopes was the largest;slope aspect had little effect on the landuse distribution;and 200~300 m altitude was the common critical interval of relief amplitudes for forest and grassland.Result from the study not only reflects the landuse changes and the influence of natural driving factors,but also favors the further study of landuse structural adjustment and soli and water conversation planning in Danjiang River basin.

Abstract:The trends and characteristics of temperature and precipitation on north and south slopes of Qinling Mountains were analyzed based on temperature and rainfall data from 1959 to 2009 collected from 39 meteorological sites in Qinling Mountains.Results showed as follows:(1) Temperature presented an increasing trend over the last 50 years.The temperature tendency rate was 0.24 ℃/10 a for the north slope and 0.15 ℃/10 a for the south slope.After the middle of 1980s,the annually averaged temperature appeared an obvious climbing trend and the temperature tendency rate for the north slope,in particular,reached up to 0.74 ℃/10 a.After 1993,Qingling region witnessed an apparent climate warming trend.(2) Over the 50 years,the average temperature in the study area presented a very remarkable rising trend in spring,autumn,and winter,with a slight downward trend in summer(p0.01).Particularly,the rising trend of the average temperature was more notable in winter and spring.Temperature in summer showed an increasing trend in the 27 years from 1983 to 2009.(3) In the past 50 years,the annually averaged precipitation on the north slope increased,while it decreased on the south slope,which led to the reduction in the precipitation difference between the north slope and the south slope.However,in the last 15 years,both of the average precipitations on the north and south slopes increased slightly,with a faster pace on north slope of Qinling Mountains(230.4 mm/10 a).This indicated that the climate over the north slope of Qinling Mountains possessed a warming and wetting trend.

Abstract:Based on the practical investigations in Wuhan City,ecological compensation criteria for agricultural land in view of the minimum farmers′ willingness to accept(WTA) are estimated by using willingness survey method.Results from the statistical analysis of 182 questionnaires show that firstly,farmers have generally recognized the essentials of farmland environmental protection and 74.45% of them have a positive attitude toward the WTA.Secondly,under the different restrictions on pesticide and fertilizer uses,farmers′ acceptance percentage decreases with the enhanced restriction and the acceptance percentage varies from 69.66% to 85.25%.Moreover,the minimum farmers′ WTA in farmland environmental protection rises with the enhanced restriction.The values for farmers′ WTA under the eight modes are between 3 866.55 and 7 624.43 RMB/hm2.In the case of the same restriction,farmers′ WTA for pesticides is higher than that for fertilizers.Lastly,farmers′ WTA is obviously correlated with their sexes,ages,and farming experiences.

Abstract:By the representative field sampling investigation and laboratory analysis,the classification and evaluation of depredated Robinia pseudoacacia plantation in the Yellow River Delta region were studied based on the 14 indexes of tree morphology(tree height,diameter at breast height,timber volume,canopy density) and soil physicochemical property(soil bulk density,soil porosity,organic matter,initial infiltration rate,stable infiltration rate,pH value,and salt content).Results indicated that the tree age of R.pseudoacacia plantation in the region was relatively single.The low quality and low-benefit classificatory criteria only by forest growth procedure and structure were unsuitable for the depredated R.pseudoacacia plantation in the region.The classification and evaluation of R.pseudoacacia plantation should combine the forest growth indexes with soil physicochemical properties.Principal component analysis showed that the main factors affecting the low-quality and low-benefit R.pseudoacacia plantation were in the order of soil bulk density soil porosity forest canopy density timber volume soil organic matter salt content.Cluster analysis indicated that the R.pseudoacacia plantation could be classified as the five types of potential type,slightly low-benefit type,medially low-quality and low-benefit type,extremely low-quality and low-benefit type,and badly low-quality and low-benefit type.According to the mean cluster value,the main features of the different types of forest,causes for the low-quality and low-benefit forest,and management measures were all evaluated.

Abstract:A comprehensive evaluation system for land eco-environmental quality is built based on land ecological risk and ecosystem service value.By taking Qianjiang City in Hubei Province as an example,the spatial control division of construction lands in the new general landuse planning(2006—2020) is evaluated according to the result from the evaluation of land eco-environment quality.Results show that high ecological risk occurs mainly in the southwest part of Qianjiang City and construction lands and lakes are faced with relatively high ecological risk.Ecosystem service value in the whole area is quite low and land with low ecological service value accounts for 52.24% of the whole city.Land eco-environmental quality of the study area is relatively uniform and has remarkable spatial distribution characteristics.The land with low ecosystem service value and medium ecological risk widely distributes around Fanwan Lake in the southwest.The spatial control division of construction lands coordinates well with land eco-environmental quality,which meets the needs in preventing the expansion of construction lands and protecting the ecological environment.However,there still exist such problems as land requirement-oriented supply and lack of classification evidences in the spatial control division.

Abstract:Spatiotemporal distribution of coordinated development degree for urban intensive landuse and ecological environment in China since 1995 was analyzed by constructing an evaluation model for coordinated development.Results from the study showed that temporally,grade for coordination degree changed from primary coordination into good coordination.In recent years,however,coordination degree exhibited a downward trend and coordinated development degree,on the whole,gradually increased year by year.Spatially,there was obvious regional disparity in coordination degree and coordinated development degree of China′s provinces.The overall coordinated development level in most provinces of the eastern China is higher than that in the middle and western China.There was a stronger correlation between coordinated development degree and economic development level.In accordance with coordination degree and coordinated development degree,the 31 provinces of China could be divided into seven categories in order to reveal the differences in economic development,natural environment,policies factors,and so on.Coordinated development between urban intensive landuse and ecological environment should be effectively promoted by improving the level of urban intensive landuse,enhancing ecological environment protection and construction,carrying out urban ecological planning,and establishing environment-friendly landuse pattern.

Abstract:Xichong River in Sichuan Province,a tributary of Jialing River,has been polluted seriously.In 2009,water quality of Xichong River was assessed to be the bad fifth grade through monitoring and analysis.The main contaminants in the river are ammonia nitrogen,chemical oxygen demand,total nitrogen,total phosphorus,and fecal coliform.By taking the Nanchong segment of Xichong River as the research object,the data from water quality monitoring at Leidashi and Laladu observation sites from 2003 to 2009 are analyzed based on blind number theory.As for the water environment capacity at the two sites,CODCr is found to be 637.01 kg/d and NH₃—N,0.76 kg/d.Chemical oxygen demand(W_CODCr) and ammonia nitrogen(W_NH3—N) exceeding the standards at the two sites are 874.59 and 116.34 kg/d,being 1.37 times and 153 times of the allowed value,respectively.In order to reach the third grade of national water quality standards,it is urgent to control the pollution of Xichong River.

Abstract:The Zhujiang River Delta is one of the rapidly developed regions in China.Based on dynamic remote sensing data of land use in 1990,2000,and 2006,spatiotemporal variations of land use and landscape pattern were analyzed with the help of the spatial analysis function and landscape pattern index in GIS.Results showed that from 1990 to 2006,the changed land of 13 580.81 km² in the region accounted for 32.93% of the total land area.Change speed in the later 6 years was faster than that in the former 10 years.The areas of urban land,rural residential land,and other construction lands expanded quickly and water bodies increased intensively,while paddy-fields,non-irrigated farmland,and forest decreased evidently.The number of patches increased remarkably,the landscape became smaller pieces,and the heterogeneity increased.Nearly round indexes of paddy-fields,non-irrigated farmland,forests,water bodies,and urban land were rather low and the shape of the patches was complicated.Fractal dimension ranged from 1.26 to 1.44 and land use types were complicated due to the continuous intense intervention by humans.Separation degree of forests essential to the total land was the lowest,while separation degrees of paddy-fields,urban land,non-irrigated farmland,and water bodies were relatively low and showed pieces-link distribution.

Abstract:According to the characteristics of urban rivers,a vulnerability assessment system for urban rivers are established so as to provide a reference for the use and protection of urban rivers.By taking Chanba River as the research object,the vulnerability of the river is analyzed by choosing several appropriate evaluation indexes,using entropy method to determine the weights,and applying fuzzy comprehensive evaluation.Results show that the area below Maduwang and Changjiawan has the highest vulnerability,whereas other places have low vulnerability.The established system can systematically reflect the vulnerability of urban rivers and make some develpment in the research on the vulnerability of water resources.The method of fuzzy comprehensive evaluation is simple and can objectively reflect the current and potential vulnerabilities of rivers.Therefore,the method can be used for vulnerability assessment of urban rivers.

Abstract:By taking Ganzhou District in Gansu Province,a typical region in the arid inland river basin of Northwest China,as a study object and constructing comprehensive ecological security index and its assessment method,environmental impact assessments before and after land use planning were performed based on GIS techniques.Results showed that there was no extremely insecure area in the study region after performing land use planning.The ecological security index in the region was 2.453 on average,corresponding to a relatively secure statue.Result from the assessment may depict the spatial characteristics of environmental impacts by land use planning and can be used to identify the spatial variation and the problems influencing ecological environment,which implies that the comprehensive ecological security index and the evaluation method developed in the study are feasible basically.

Abstract:Drought disaster is one of the main natural disasters in Shaanxi Province,which is often called "9 droughts out of 10 years".It impacts the people′s lives and social production to different extents.Therefore,it is of great significance to scientifically analyze and assess drought disaster for all levels of government to develop prevention and mitigation measures.The precipitation and other meteorological data from the 96 weather stations of Shaanxi Province in the period of 1981—2010 were used for analyzing drought disaster features by the means of the percentage of precipitation anomaly drought index in detail.The following conclusions are drawn.(1) Drought disasters in Shaanxi Province distributed extremely unevenly,and basically,more in Northern Shaanxi Province and less in Southern Shaanxi Province.(2) There were both widespread drought disasters over all the province and regional drought disasters in Shaanxi Province and the frequencies of regional drought disasters in Northern Shaanxi Province and Guanzhong area were higher than that in Southern Shaanxi Province.(3) The seasonal variations of drought disasters have the significant differences in Northern Shaanxi Province,Southern Shaanxi Province and Guanzhong area.The seasonal variation of drought disasters was the greatest in the North Shaanxi Province,followed by in Guanzhong area and Southern Shaanxi Province in turn.(4) Some of persistent drought disasters occurred in the same season and some persisted for two seasons.On the whole,the occurrence of drought disasters was more in spring,autumn or in the periods from spring to autumn and from autumn to winter.The persistent drought disasters were less in Southern Shaanxi Province.

Abstract:According to the evaluation principle of dam system planning and the analytical hierarchy process (AHP),three hierarchies and nine indicators are selected as an evaluation system of dam system planning. Calculation method for each index in the evaluation system of dam system planning is obtained by analyses, weighted value of each index is determined,and finally a comprehensive index of dam system in small watershed is calculated.The computational results show that the greater the comprehensive index in small watershed, the better the economic,social and ecological benefits are.Therefore,the greatest comprehensive index may be selected as the best solution in the schemes for dam system planning in small watershed.The approach can be recommended for practical uses.