Abstract:For a certain initial state of the Yunnan laterite and a certain slope, slope length,the effect of the physical and chemical properties of the Yunnan laterite on the erosion on slope under the f rainfall conditions is studied by using artificial simulated rainfall test method. The results indicated that:(1) The content of clay particles in the group of laterite is the most significant for slope erosion under rainfall effect. When laterite content increased about 8.1%, the erosion modulus increased by 25.8 g/(m₂.h);(2) The more the initial water content of laterite is deviated from the optimum water content, the erosion modulus of laterite became bigger. When the initial water content of laterite increased from 24.6% near the optimum water content to 30.5%, the erosion modulus increased from 110.4g/(m₂.h)to 121.3g/(m₂.h). (3) Under the conditions of initial dry density 1.0g/cm₃、1.1g/cm₃、1.2g/cm₃、1.3g/cm₃、1.4g/cm₃, the laterite erosion modulus was the change trend of the two curves which firstly increased and then decreased. At the initial dry density of 1.2g/cm₃, the erosion modulus reached a maximum of about126 g/(m₂.h).(4)The content of Fe₂O₃ and Al₂O₃ decreased by the effect of rainfall on the slope. The content of Fe₂O₃ decreased from 8.143% in the initial state to 8.591% and the content of Al₂O₃ decreased from 22.242% in the initial state to 20.967% on the surface of the slope foot. The content of Fe₂O₃ and Al₂O₃increased with depth in the slope. The content of Fe₂O₃ increased by 0.407%, and the content of Al₂O₃ increased by 0.861%. The changes of iron and aluminum oxide content will lead to the changes in the resistance to erosion of laterite .

Abstract:The soil-rock mixed colluvial slope was selected to study the feature of sediment yield that was affected by four gravel contents(0%，20%，40%，60%) and four discharges(2 L/min ，4 L/min，8 L/min，16 L/min) in indoor artificial runoff experimental condition．The results showed that: the process of sediment yield indicated that the sediment yield overall increased first, and then decreased, reached a steady finally with erosion duration. Sediment volume increased with increasing discharge, whereas sediment concentration decreased with increasing discharge; sediment volume and sediment concentration firstly decreased and then increased with increasing gravel content at the discharges of 2 L/min and 4 L/min, existing critical gravel content (20% - 40%), but sediment yield and sediment concentration increased with increasing gravel content at the discharges of 8 L/min and 16 L/min. According to the relationship between sediment yield rate and sediment concentration, it was indicated that the effect of gravel content on sediment yield existed critical gravel content (20% - 40%). Gravel content and discharge could be used to predict sediment yield rate of soil-gravel mixed colluvial slope correctly, but prediction for sediment concentration was poorer. The effects of discharge were higher than gravel content.

Abstract:To investigate the effect of biochar on dehydrogenase activity and iron reduction in paddy soil, twoSkinds of paddy soil in different areas were anaerobically incubated under the addition of biochar with different partical sizes. Changes of dehydrogenase activity, Fe(II) concentration and pH were determined during incubation. Results showed that biochar promoted dehydrogenase activity and microbial Fe(III) reduction. Dehydrogenase activity and iron reduction potential in paddy soils increased with the decrease of the biochar practical sizes. Dehydrogenase activity was 3.13 and 2.60 μg/(mL.g.min), and Fe(II) concentration was 8.07 and 7.44 mg/gwithout adding biochar in two paddy soils, respectively. With adding biochar, dehydrogenase activity arrived at 4.35 and 4.18 μg/(mL.g.min), and Fe(II) concentration was 9.01 and 8.18 mg/g. CCA showed a significant correlation between initial pH of paddy soils and iron reduction potential, which indicated that the effect of biochar on iron reduction was different due to the disparity of soil property. Dehydrogenase activity and Fe(II) concentration showed a significant correlation, and both of them promoted each other during incubation.

Abstract:In the paper, 22 typical watersheds were selected in the MCSR of middle reaches of Yellow River to probe the fractal characteristics of CJs. The ASTER GDEM was used as the basic data sources, and the box dimension (BD) and correlation dimension (CD) were used to measure the difference of the spatial patterns of the CJs. In addition, the meanings and the influence factors of BD and CD were discussed. Finally, a cluster analysis was performed based on BD and CD to investigate the difference of soil erosion. (1) The results shown that the fractal characteristics of CJs were clear, while the dimension value changed with the measure methods. Among the 22 watersheds, if one’s BD was bigger than others, so did it’s CD. (2) The results also shown that the CJs’ fractal characteristics were relevant with the geomorphologic types of Loess Plateau. Although the value of BD and CD was different in different watersheds, while the sorted groups always remained the same, which were sorted as Loess Ridge-hillock gully, broken Loess plane, Loess Ridge gully, Loess plane, Loess hill, Loess Hillock-ridge gully and wind erosion Loess sand dunes. (3) When BD and CD were used as the main input parameters in the procedure of cluster analysis, the results shown that the 22 watersheds can be divided into 4 groups. The groups can be classified into 4 different erosion ones, namely serious erosion regions, strong erosion regions, medium erosion regions and light erosion regions. All in all, the results shown that the fractal dimensions can be used to depict the different patterns of CJs in Loess Plateau, and that maybe can be regarded as the indicators of erosion of loess gullies.

Abstract:Land use has a significant impact on spatial soil moisture patterns, particularly in sensitive and poorly managed regions such as karst grassland of Guizhou. This study identified the factors that control soil moisture patterns under different grazing intensities in the pasture grazing system of Guizhou. Three different levels of goat grazing intensity were sampled for various soil moistures including no grazing, moderate grazing and heavy grazing. The data were analyzed using correlation and geostatistical analysis. The results indicated that obviously trend were showed on the average and spatial heterogeneity of the pasture soil moisture as the changing of grazing intensity and soil profile. Under different grazing intensity, soil moisture content of 0-10 and 10-20 cm layers were for NG > HG > MG, soil moisture content of 20-30 cm were for MG > NG > HG, coefficient of variation were moderate variation (10% < CV < 100%), high soil moisture variation was during medium level of the average water content. Moran"s I autocorrelation analysis show that soil moisture had strong autocorrelation, and the correlation was mainly affected by grazing. Semi-variance analysis showed that spatial distribution characteristics of soil moisture was gathering distribution. The C/(C₀ C) values of soil moisture were varied b during 0.500 to 0.817, which suggested that soil moisture had moderate or strong spatial correlation. The variation region of soil moisture under different grazing intensity were from 2.77 to 15.61 m, which suggested that the ecological process affected by soil moisture was altered under different grazing intensity. The Kriging map further showed a great spatial heterogeneity of the soil moisture content. Moreover, the soil moisture spatial variability in this region mostly contributed to grazing intensity.

Abstract:In this study, we aimed to investigate the effect of different amounts of residual plastic film on soil water horizontal diffusion process. By using the horizontal soil column simulation investigation, Six kinds of residual plastic film(0,80,160,320,640 and 1280kg/hm2) were designed with triplicate. The water wetting front transport distance, the accumulative infiltration amount and soil water content were determined, then we could calculate the Boltzmann coefficient and water diffusivity by using iterative method. The results showed that the migration rate of horizontal wetting front, the accumulative infiltration amount and volumetric soil water content gradually declined with the increase of residual plastic film amount. When residual plastic film amount was more than 160 kg/hm2, the migration rate of horizontal wetting front and the accumulative infiltration amount would dramatically reduce. There were extremely significant positive correlation relationship between the amount of residual plastic film and retardation coefficient. When the amount of residual plastic film ranges from 80 kg/hm2to160kg/hm2, increase rate of retardation coefficient reached up to 251.15%. The distance from stronger retardation region to infiltration point was enlarged with increase of residual plastic film. However, Boltzmann coefficient and water diffusivity were gradually declined, driving force of soil matric potential on soil water diffusion and soil water holding ability wore off. The horizontal diffusion process of soil mixed with residual plastic film still conforms to single parameter model of soil water diffusivity. Our results suggest that the residual plastic film as soil pollutant would reduce migration rate of horizontal wetting front, accumulative infiltration amount and soil water diffusivity, the retardation effect of residual film on soil water diffusion will enhance with residual plastic film amount increasing.

Abstract:The Gurbantünggüt Desert, located in Junggar Basin in north Xinjiang, is the second largest desert in China, fixed and semi-fixed dunes are the main types in the desert. In this paper, 0-100cm above-ground sand were collected by sand traps, which sited perpendicular to the main wind direction at May to September 2015, at the same time, using a portable weather station recorded wind speed, wind direction, atmospheric pressure and other meteorological data. Sand flow characteristics such as sand transport profile, particle composition, particle size parameters and average saltation height of sand were analyzed. Results showed that within 0-100cm, as the altitude (H) increases, the sand transport profile (Q) with a negative power function(Q=a×H-b) decrements, the fitting equation has a high correlation coefficient, 73.7%～97.9%of sand movement mainly in near-surface of the range of 0-40cm. according to the American of system of soil texture standard, the main texture was fine sand(0.1-0.25mm) followed by medium sand (0.25-0.5mm), the mean grain-size(M) which calculated by graphical method of Folk and Ward between 120~250μm. With the growth of height, the content of very fine sand increased,medium sand content reduced,The mean grain-size was showing a decreasing trend. The different of wind speed and local vegetation distribution caused the variation of sand flow structures, average saltation height of sand was positively correlated with wind speed, and the change of wind direction also due to the difference of distribution of average saltation height between each sand traps, the main reasons for this phenomenon may be the difference land surface pattern of both side of monitoring point.

Abstract:Returning agricultural waste is the important way of developing circular agriculture and low-carbon economy. In maize growth season, this study adopts the static method, such as NPK keep weight (N 240 kg/hm2, P2O5 100 kg/hm2, 120 kg K2O/hm2) conditions, straw, cow muck, chicken manure and chemical fertilizer was studied with soil and its influence on soil CO2 emissions and carbon fixation. The results show that the fertilizer promoted the soil CO2 emissions, 100% straw crushing returning NPK fertilizers (S1) promoting effect of soil CO2 emissions is most obvious, the average emission flux of 389.0 mg/m2?h; Followed by chemical fertilizer fertilization (S4). S1, S2, S3 and S4 handling in 6, 7, 8, three month average CO2 emission flux performance for S4 > S1 > S3 > S2, accounted for 80.1% of total emissions throughout the growing season, 78.9%, 78.8% and 78.9%, showed that fertilization of chemical fertilizer treatment (S4) in the maize growth season CO2 emission flux of up to 624.9 mg/m2?h. Various fertilizer treatments on maize growth season two CO2 emissions peak stage, is closely related to the two nitrogen fertilizer (urea) topdressing, twice topdressing nitrogen after CO2 flux values of performance for S4 > S1> S3 > S2, that use agricultural waste of nitrogen instead of nitrogen fertilizer, can reduce CO2 emissions. 50% cattle manure organic nitrogen application in the field with 50% nitrogen fertilizer (S2) can obviously increase soil organic carbon content. 50% chicken manure organic nitrogen application in the field with 50% nitrogen fertilizer (S3) can obviously improve the maize organs and plant carbon content, among them, the S3 processing plant carbon content up to 9.59 t/hm2, promoted the corn carbon fixation; While 100% straw crushing returning NPK fertilizer nitrogen (S1) does not improve maize organs and plant carbon content, and even lower than that of single chemical fertilizer (S4).

Abstract:Take the long-term grazing point on Stipa breviflora desert steppe in Inner Mongolia plateau as the research object, randomized blocks were adopted with 0.93 (LG), 1.82 (MG), 2.71 (HG), 0 (CK) sheep/hm2 and the wind tunnel test of undisturbed soil samples were carried out in order to study the quantitative relationship between grazing intensity and wind erosion rate, and to estimate the total amount of wind erosion under different grazing intensities in Desert Steppe. The results indicated that the community structure characteristics of different grazing intensity treatments were significantly different (p < 0.05), but the soil crust and change of soil particle size composition in 0~5cm depth were not significant (p > 0.05). The equation of wind velocity and wind erosion rate in different grazing intensity treatment areas has a better fit index, however, the equation fitting coefficients R2 of HG and MG are larger than that of LG and CK, and the parameter B for characterizing wind speed sensitivity increased from 0.15 in CK to 0.21 in HG region with the increase of grazing intensity, it showed that the wind erosion rate was more sensitive to the increase of wind speed under grazing condition. Wind erosion rate had a very significant positive correlation with wind speed and grazing intensity（r=0.601 and r=0.563, p<0.01), and highly significant negative correlation with coverage and height（r=-0.544 and r=-0.535, p<0.05). Based on the two years’ data of small meteorological station and the equation of soil wind erosion, the annual wind erosion amount was between 110-680 t/km2.year on Stipa breviflora desert steppe, the annual average amount of wind erosion per unit area increased gradually with the increase of grazing intensity, the average annual wind erosion amount was 115.24 t/km2.year in CK treatment area, it was about 17% of HG area wind erosion amount that was 648.95 t/km2.year, MG area and LG area were 60% and 23% of HG area, respectively.

Abstract:By the method of artificial rainfall in hall, analysed the difference of effects on runoff and sediment reduction between Quercus variabilis with litter layer and no litter layer under different slope gradients and rainfall intensity conditions. The results showed that: (1) Compared to the slope with Quercus variabilis alone, The undergrowth litter of Quercus variabilis can effectively reduce the runoff on the slope,and the effect of runoff reduction was best under 60mm/h rainfall intensity and slope of 10°, up to 25%. (2)The undergrowth litter of Quercus variabilis significantly improved the sediment reduction efficiency and the efficiency was highest under 90mm/h rainfall intensity and slope of 10°, up to 125%. (3) The time of the slope initial runoff generation was delayed and the speed of runoff was reduced with the existence of litter layer, the litter can also reduce the total runoff yield(6.60-28.17%)and sediment yield(11.08-65.08%) . (4)Litter layer has a better effect on reducing sediment than reducing runoff．

Abstract:Better understanding of ecosystem organic carbon change after forest restoration on red eroded wasteland is essential to the carbon stocks recovery of the ecosystems with low carbon density. We investigated above- and below-ground carbon pools in wasteland on a slightly eroded red soil (HD), four artificial plantations, Schima superba and Pinus massoniana mixed forest (MM) , Broad-leaved forest (CK), Citrus reticulata forest (GJ) and closed forest(FY) that had been established on HD in 1984 in the subtropical China. The ecosystem carbon pool in MM(267.22 t/hm₂)、KY (233.48 t/hm₂)、FY (112.01 t/hm₂) was significantly higher than in HD (27.04 t/hm₂),but there was no significantly difference between GJ(84.16 t/hm₂) and HD(P＜0.05). The plant carbon pool in MM(187.88 t/hm₂)、KY (164.17 t/hm₂)、GJ(15.24 t/hm₂)FY (61.75 t/hm₂) was 43.56、38.06、3.53、14.32 times as that in HD(4.31 t/hm₂) respectively. The soil carbon pool in MM(79.34 t/hm₂) 、KY(69.31 t/hm₂) 、GJ(68.93 t/hm₂)、FY(50.26 t/hm₂) was significantly higher than in HD(22.73 t/hm₂) (P＜0.05). The annual fine root biomass in MM(112.15 g/m₂)、KY(88.71 g/m₂)、GJ(257.70 g/m₂)、FY(211.21 g/m₂)was 1.21、0.96、2.79、2.29 times as in HD(92.33 g/m₂)separately,which was significantly correlative with soil organic carbon density in the same soil horizon(P<0.05).The mean accumulation rates of ecosystem, above and below ground carbon pools in different restored forests range 2.04-8.58、0.39-6.56、0.98-2.02 Mg C/(hm₂?yr₁)respectively. Our results indicate that forceful artificial intervention maybe successful management practices to achieve rapid carbon accumulation on red eroded wasteland.

Abstract:A rainfall simulation study was conducted to examine the sediment particle dynamic distribution characteristics in splash and sheetwash process. In order to reveal the surface soil aggregate mechanical breakdown, the experimental treatments included three rainfall intensities (30, 60and 90mm/h) of representative rainfalls, two slope gradient (5°、15°) and three average vegetation coverage (0%, 30%, 75%). In our experiment, sediment samples detached by raindrops splash and transported by runoff flow were collected separately. The results showed that sediment particle size mainly concentrated in the 0.1~0.05 mm and 0.05~0.02 mm. For the splash sediment, sand particlesS(2-0.05 mm) content is higher than sheetwash sediment, and silt (0.05-0.02 mm) and clay particles (<0.002 mm) is lower. The MWD value of spalshed is greater than the MWD value of washed. With regard to sediment size variation characteristics in erosion process, the coarse sand (2-0.25 mm) and fine sand (0.25-0.05 mm) decreased and silt (0.05-0.02 mm) and clay particles (<0.002 mm) increased with rainfall duration to sediment particles by splashed. The sheetwash sediment particles size mainly includes silt (0.05-0.02 mm) and clay particles (<0.002 mm).The relationship of the each particles size by splashed and washed with slope runoff flow and water depth indicates slope erosion process is closely related to the hydrodynamic factors. Meanwhile, the fractal dimension of sediment particles size distribution (D) and relative mechanical breakdown index (RMI) of soil aggregates has better fitting, and reflection mechanical breakdown degree of slope splash and sheetwash sediment particles with rainfall duration. The experiment results can provide a theoretical reference for agricultural water-soil engineering and slope erosion process prediction model of Rocky Mountain Area.

Abstract:The large deviation of engineering accumulations erosion prediction by the model of USLE is due to the unit plot and the soil erodibility factor cannot be directly used to erosion prediction of engineering accumulations . This study aims to define the gradient and slope length of engineering accumulations unit plot according to the survey of engineering accumulations from six water erosion area in China, analysis the improvement method of engineering accumulations erodibility factor according to relative research achievements and prove the feasibility of this improvement method by published data. Survey results show that the gradient, slope length and surface composition of engineering accumulations from six water erosion area is large different from the unit plot of the model of USLE. So, we choose the mode 35° of gradient and the mean 5m of slop length of engineering accumulations from six water erosion area as the gradient and the slop length of engineering accumulations unit plot. In order to distinguish soil erodibility factor K from engineering accumulations erodibility factor, we give engineering accumulations erodibility factor a name of soil and rock factor (Tr). Bring the index of unit volume soil-rock mixture"s total surface area of rock (Cs) into soil and rock factor, building a function of Tr with soil erodibility factor K. Verification results show that this improvement method of engineering accumulations erodibility factor is reasonable. In conclusion, the defining of the gradient and slope length of engineering accumulations unit plot and the improvement method of engineering accumulations erodibility factor is significant to enhance the accuracy of engineering accumulations erosion prediction by the model of USLE.

Abstract:The effect of mining subsidence on soil bulk density, water moisture content, field capacity, saturated hydraulic conductivity and soil disintegration rate were studied based on field survey, sample collection and lab analysis in mining area of the Loess Plateau. The results showed: bulk density, water moisture content and field capacity of subsidence soil showed low to moderate CV, but saturated hydraulic conductivity and soil disintegration rate were high; soil bulk density was increased caused by mining subsidence, but the impact was little and there was not obvious rule on water moisture content; field capacity saturated hydraulic conductivity and soil disintegration rate significantly affected by the collapse (P<0.05), where field capacity decreased from 6.2% to 15.5% compared with undamaged areas; no significant difference was detected between reclaimed soil and undamaged soil (P>0.05), and differences among depths was also not significant(P>0.1).

Abstract:In order to reveal mechanism of nutrient transfer ,two plant (alfalfa and green foxtail), four plant density (0, 80, 120,160 plants square metre), two treatment（complete plantlet and underground biomass）was carried out by simulated rainfall experiment. The results showed that: grass could control erosion effectively, which the effect of plant to reduce erosion was related to the underground biomass closely and the effect of aboveground biomass was not significant. Nutrient Loss with erosion of bare slope was 1.49～5.90 times (total nitrogen), 1.24～8.61 times (total phosphorus), 1.17～1.82 times (available potassium) than vegetated slopes, however, concentration difference of nutrient loss with erosion between bare slope and vegetated slopes was not obvious. Grass controlled nutrient loss with erosion by reducing the amount of sediment mainly, which underground part of foxtail was more effective than alfalfa and aboveground biomass of alfalfa was more effective than foxtail. Meanwhile the role of underground part to reduce nutrient loss was gradually significant with the plant density increased. Grass could reduce the nutrient loss with runoff effectively, and the total nitrogen loss ratio of slope with underground biomass and complete plants was 1.02～1.05 (green foxtail), 1.10～1.14 (alfalfa), indicated grass control nutrient losses with runoff mainly by underground parts, which underground biomass of foxtail was more effective than alfalfa. With the plant density increase, effect on controlling total nitrogen and total phosphorus loss with runoff by underground biomass gradually strengthened but the available potassium didn’t have significant change. The dynamic change of runoff nutrient concentration decreased, than remain stable, which the power function best fit. The change process of total nitrogen and total phosphorus were related to plant situation closely, and total phosphorus changed with plant was not obvious.

Abstract:This study aimed to optimize the tillage system and realize the effect of maize production and efficiency increased under the completely film mulched alternating narrow and wide ridges with furrow planting for one film used two years, stable-increasing grain yield and protecting soil quality in The experiments were conducted on the effect of tillage system including subsoiling tillage - no tillage, no tillage - no tillage, rotary tillage - no tillage, and traditional tillage- no tillage (as the control) on maize yield, water use efficiency (WUE), economic efficiency, soil physical characteristics under the completely film mulched alternating narrow and wide ridges with furrow planting under one film used two years, the results showed that the system of subsoiling tillage - no tillage could significantly increased the grain yield, WUE, harvest index, total output value and output ratio, which increased by 22.8%, 22.0%, 15.0%, 17.4% and 17.4%, respectively, compared to that of the control under the completely film mulched alternating narrow and wide ridges with furrow planting. Meanwhile,the system of subsoiling tillage - no tillage could reduce the soil surface bulk density and soil compaction, increase soil total porosity, the content of large mechanical stability aggregates and waterstable aggregates. Above of which indicated that the maize yield and incomes were promoted and soil physical characteristics were protected used the tillage system of subsoiling tillage - no tillage under the completely film mulched alternating narrow and wide ridges with furrow planting, it should be widely extended in maize production in hilly and gully region on loess plateau.

Abstract:Using Granier-type thermal dissipation probes, sap flow velocity (V) of two species (Cunninghamia lanceolata, Symplocas setchuensis) were monitored in three depths (10mm, 30mm, 50mm) of xylem from July to September, 2015, at Jinyun Mountain of Chongqing to analyze the radial variations of V and estimate trees transpiration accurately. The results showed that the radial pattern of V for Cunninghamia lanceolata was: V30～50mm＞V10～30mm＞V0～10mm. V30～50mm was 1.65 times of V0～10mm and V10～30mm was 1.12 times of V0～10mm. The radial pattern of V for Symplocas setchuensis was: V10～30mm＞V0～10mm≈V30～50mm. V10～30mm was about 2.6 times of V0～10mm and V30～50mm; There were significant liner relationships between every two depths; The daily variations of V in three depths of xylem displayed unimodal or bimodal curves; The value of V was highest in July and the transpiration was stopped in noon. There were temporal and spatial differences in start time and peak time of sap flow, which was earlier in July than in August and September. The start time was earliest and the peak time was latest at the plot where V was maximal in radial xylem. The daily transpiration of Cunninghamia lanceolata and Symplocas setchuensis were 7274.815g and 12481.494g, estimated by different V in different depths. The error by omitting radial variations in V were 9.83%～17.89% for Cunninghamia lanceolata and 42.41%～66.88% for Symplocas setchuensis, its coefficient of variation (CV) were 26%～45% and 19%～26%.

Abstract:The content of soil stone is rich in the rocky mountain area of North China, which has an important influence on the macropores and water transport. The study was carried on Miyun reservoir in Beijing, in order to explore the relationship among stones, macropores and the soil saturated hydraulic conductivity. The results showed that: (1) Volume content of stone is in the range of 7.10%~22.05%, while mass percent is range from 10.76% to 38.20%. Stones in the size of 5~10mm has highest content in soil. The percentage composition of stone with the slope aspect has regulation as follows: adret slope > semi shaded slope> shade slope; (2) The macropore density of equivalent pore >1.5mm showed very significant correlation relationship with stone content (P<0.01).The volume content of stones with the size >5mm has a significant correlation relationship with macropore density (P<0.05). It illustrate that stones mainly affect macropores with large size, and stones in size of >5mm have a key influence on the formation of macropores. (3) The amount of equivalent pores with size >1.5mm only accounted for 1.41% of the total macropores, but determined the 54.44% of the saturated conductivity. The hydraulic conductivity and the amount of equivalent pores with size >1.5mm has a linear relationship. Exploring the relationship among stones, macropores and saturated hydraulic conductivity can provide a comprehensive understanding of forest soil and water conservation mechanism and hydrological adjusting process. It can also provide theoretical basis to the water resource utilization and protection in Rocky Mountain, and the establishment of hydrological process model.

Abstract:The soil is natural resources for human survival, and land use is the most important and most direct activity of human intervention. The effects of different land use patterns on soil nutrient content can provide a basis for the rational use of land resources and the efficient production of crops. This study selected Heze city of the Yellow river alluvial plain area as the study area. There are four land use types: vegetableSland, irrigableSland, orchard, and forestSland, and 13 kinds of nutrient data: N, P, K and organic matter, etc. By using the software of SPSS ANOVA single factor variance analysis method, effects of different land use types in plain area of Yellow River on soil nutrients was studied. The results showed that: The soil pH value of forestSland and orchard was relatively high while the value of irrigated land and vegetable land was relatively low, but they were all weakly alkaline; the contents of soil organic matter, available K, available P and total N were greatly influenced by land use, and the ranking of content from high to low was vegetableSland, irrigableSland, orchard, and forestSland, but the effect of land use on the slowly available K was not significant; The ranking of available s content from high to low also was vegetableSland, irrigableSland, orchard, and forestSland, same as organic matter; Higher content of available Zn and available Cu and available Fe were in irrigated, while available Mn, available Mo and available B in forestSland was higher, and the content of microelement in the vegetable land was generally low. The research results will provide scientific basis for soil fertilization and utilization management in Yellow River Alluvial Plain Area, and it has positive guidance for rational utilization and protection of land resources in this area.

Abstract:In order to study the characteristics of soil seed banks of soil slope and soil-rock slope in mountainous area of Beijing, species composition, density and the relationship between soil seed banks and the above ground vegetation were analyzed. Field surveys backed with indoor germination experiments were conducted in three different areas of Beijing, Jiufeng Forest Park, Mount Baihua and Mount Yunmeng. There were found 54 species, which belonged to 26 families,53 genera, in which there were 23 herbs,18 perennial herbs, took the percentage of 78.2. The density of seed was between 16166.67±2165.16~20612.50±2717.32 seed/m2. There was no significant difference of seeds between 0-5cm and 5-10cm for soil depth. Some vertical trends were found for the seed distribution. The density of seed was higher in 0-5cm of soil depth than 5-10cm of soil depth. There was no significant relationship between seed and above-ground vegetation. Similarity coefficient of species composition between soil seed banks and above-ground vegetation were no high, which were between 0.390~0.492.From this study we found that various seed located in the study area. In addition, high diversity of species helps seed to grow under proper conditions. It can be considered to play a role in the environmental restoration of slope in Beijing area as soil replacement.

Abstract:In this study, our goal is to estimate the water regulating ability of terraces ,which is one of the most important soil and water conservation measures in the Three-Gorge Reservoir Region,as well as the south China.Six testing fields at the different height were selected ,which with two kinds of land use types including abandoned land and slope farmland,and then we analyzed the storage capacity of yellow soil and the impact factors of soil reservoir after terracing in Jinyun Mountain ,Chongqing.The results showed as follows:(1)In the test area,soil reservoir storage was mainly affected by the thickness of the soil layer,and land use types before terracing were also related;(2)Soil property changes,especially soil porosity and soil texture changes caused by terracing ,also had an important impact on soil reservoir characteristics;(3)Under the designed once-in-a-century rainstorm in this area,terraces could reduce more than 30% of the storm runoff theoretically simulated by simplified runoff formation model,so terraces would play an important role in drought or waterlog prevention.

Abstract:The Pinus massoniana – Quercus acutissima mixed forest in low mountain and hilly areas of western Zhu madian, Henan Province was selected as research object, soil organic carbon ( SOC ), soil dissolved organic carbon ( DOC ) and dissolved organic nitrogen ( DON ) contents and their response pattern to exposures, soil depths ( 0—10 cm and 10—20 cm ) as well as basal area was detected. The results showed that exposure and basal area have a significant impact on the storage of SOC and DOC ( P<0.05 ). Furthermore, the influencing factors for SOC, DOC and DON storages were different under sunny and shady slope. For example, in sunny slope, the major factor for SOC content is available potassium, while it is total nitrogen in shady slope. Soil total nitrogen is the main factor for DOC and DON contents in both exposures. Moreover, soil depth also has a significant impact on SOC, DOC and DON storage ( P<0.05 ), which tended to decrease with the increase of soil layer, showed surface enrichment phenomenon. From correlation analysis, SOC, DOC and DON storages showed significant correlations with soil physical properties, i.e. soil moisture content, soil compactness and particle composition. Moreover, SOC, DOC and DON showed a positive correlation with each other, and had positive correlations with soil total nitrogen, effective nitrogen ( nitrate-nitrogen, ammonium-nitrogen and available nitrogen ), available phosphorus and available potassium ( P<0.01 ), indicating that soil nutrients are vital factors for the spatial distribution of soil organic carbon storage and soil dissolved organic matter in Pinus massoniana – Quercus acutissima mixed forest.

Abstract:The characteristics of 26 geochemical elements and their environmental significance in Luyang Lake sediments (0—280 cm) for last 30,000 years in Guanzhong basin were discussed based on the element contents determinated by fluorescence spectrometer and plasma emission spectrometry, the OSL dating results and the R—type cluster analysis. Results show that: geochemical elements in Luyang Lake sediments can be divided into four categories: the first include Si, Zr, Hf, Na, indicating the decreased exogenetic clastics and the lake shrink after 4.6 ka B.P.; the second include Ga, U, Sr, indicating the arid climate at 4.6 ka B.P. and 2.0 ka B.P.; the third include Cu, Hg, Mn, Mg, indicating the increasing lake salty since 4.6 ka B.P.; the fourth contains 15 elements, including Ti, Sb, Pb, V, Th, Co, Fe, Bi, Cs, Zn, Ni, Rb, Ga, K, Al, indicating the increaseing lake salinity and the human activities around the lake. Different behaviors of geochemical elements in Luyang Lake show that: the sedimentary environment in Luyang Lake was stable between 33 ka B.P. and 10.4 ka B.P., then the lake salinity decreased in the early Holocene (10.4—4.6 ka B.P.) while increased after 4.6 ka B.P. accompaning with the reduced exogenetic clastics, the drying process at 2.0 ka B.P. caused a lot of salt formation, then the climate turned relatively wet, however, the increasing human activities accelerated the lake disappearance.

Abstract:To evaluate the water conservation capacity of Pinus tabulaeformis forest with different ages quantitatively, water balance method and comprehensive water storage method were used to investigate the rainfall redistribution, litter water-holding capacity, soil water storage capacity of three Pinus tabulaeformis stands with different ages in Liaohe source region. The results showed that: (1) During the observation, a total of 112 times rainfall were observed, cumulative rainfall was 902.2 mm, the average rainfall was 8.1mm; the light rain, moderate rain, heavy rain and torrential rain accounted for 25.2% 35.5%, 26.4% and 12.9% of the total rainfall, respectively. (2) The percentage of crown canopy interception, forest precipitation and sap flow of Pinus tabulaeformis forests in total rainfall were 24.1%, 72.9% and 3%; there was a significant positive linear relationship between forest precipitation inside and outside; with the increase of forest age, the capacity of crown canopy interception increased, and the sap flow increased first and then decreased; (3) The maximum moisture capacity of litter, the maximum of moisture absorption ratio and effective interception amount increased with the increase of forest age; (4) With the increase of forest age, the soil bulk density reduced, but the total porosity, soil infiltration rate and storage capacity increased; (5) The water conservation capacity of Pinus tabulaeformis forest with different ages performed : mature forest > nearly mature forest > middle-aged forest. In different aged Pinus tabulaeformis stands, the ability of rainfall distribution and retention capacity and water conservation capacity increased with the succession.

Abstract:Evapotranspiration is the important component of ecosystem hydrological and energy-balance. This study analyzed the evapotranspiration feature over flat underlying surface based on eddy covariance in Badaling Forest Farm in Beijing. We analyzed the evapotranspiration components via PT-Fi model and response to meteorological factors. The results of typical daily evapotranspiration variation in non-uniform underlying surfaces showing that the whole day were divided into 4 stages, 0:00 to 5:00 and 20:00 to 24:00 (night)was stable stage, 5:00 to 12:00 was increasing gradually stage, 12:00 to 14:00was fluctuant stage and 14:00 to 20:00 was decreasing stage. 24h averaged evapotranspiration in one month show that evapotranspiration monthly variation was accordance with the change of daily variation, expect the curve was smoother. According to the seasonal variation, evapotranspiration increased slowly from April to May, from June to September, the evapotranspiration arranged in the fastigium, while the evapotranspiration decreased rapidly from October. Total evapotranspiration during study period was 532.92mm, the components of ET--vegetation transpiration and soil evaporation were 394.48 mm and 138.44mm respectively, and the proportion were 74.02% and 25.98% respectively. The correlation between evapotranspiration and meteorological factors indicates that: correlation of solar radiation and evapotranspiration shows that: sunny day in summer (0.9484)>sunny day in spring (0.7909)>sunny day in autumn (0.6917), sunny day in summer (0.9484)>cloudy day in summer (0.8828). Correlation between evapotranspiration and temperature shows that: sunny day in summer (0.6735)>sunny day in autumn (0.4222)>sunny day in spring (0.1826)>, sunny day in summer (0.6835)>cloudy day in summer (0.647). Quantified the influence of meteorological factors on evapotranspiration, effect of solar radiation: sunny day in summer（0.3585 W﹒m-2/ W﹒m-2）>sunny day in spring（0.0474W﹒m-2/ W﹒m-2）>sunny day in autumn（0.0525W﹒m-2/ W﹒m-2），sunny day in summer（0.3585W﹒m-2/ W﹒m-2）>cloudy day in summer（0.2510W﹒m-2/ W﹒m-2）. Temperature：sunny day in summer（19.5535 W﹒m-2℃-1）>sunny day in spring（2.3224W﹒m-2℃-1）>sunny day in autumn （1.3516W﹒m-2℃-1），cloudy day in summer（21.0650W﹒m-2℃-1）>sunny day in summer（18.0420W﹒m-2℃-1）.The correlation analysis of evapotranspiration and rainfall shows that rainfall played negative effect on evapotranspiration, but there was a critical rainfall amount, that was to say the evapotranspiration would decrease until rainfall reached a certain amount. Analysis on combined effect of meteorological factors on evapotranspiration indicated that the maximum effect factor was temperature with the contribution rate of 40%~60% during research period. Contribution rate of solar radiation and relative humidity varied in different seasons.

Abstract:SBased on the soil desiccation and water shortageSproblems inSthe semi-arid Loess Plateau in China, the soil water and temperature ofS0-1000Scm soil layers in a dense jujube plantation was measured duringS2012 to 2015 in order to investigate the mechanism of soil water loss in jujube plantations in the region.SThe results of our analysis showed thatSevaporation is the main reason of the soil water loss in non-growth period: the soil water moved toward the upper soil layer and eventually converted to water vapor when near the soil surface, then diffused into the atmosphere. The soil water loss in the non-growth period is serious: the amount of soil water loss in 0-200 cm soil layerSwasSup to 85.64-92.34 mm, which is about twice as much as contemporaneous rainfall. BothSthe water loss amount and the net flux of soil water vapordecreased with the increase of soil depths in the 0-540 cm soil profile. The most active layer of soil water loss is 0-11 cm.

Abstract:By the method of substituting temporal serial with spatial serial，and taking six sandy grasslands with different habitat types (H1, hard sierozem，H2, sandy sierozem，H3, fixed sand dune，H4, emifixed Sand dune，H5, semimobile Dune，H6, mobile sand dune) in desert steppe region as test objects，this paper studied the response of plant community succession on sandy grassland desertification process by analyzing the composition of its soil particles and grassland plant community structures and features, the results showed that: the species richness was 9，12，9，9，9 and 5 respectively in the communities, of which the desertification succession was from hard sierozem to mobile sand dune. For life form composition of all communities along the desertification succession, the dominant species were the perennial herbaceous plants from hard sierozem to sandy sierozem, and the dominant species were the annual herbaceous plants from fixed sand dune to emifixed Sand dune, then, the dominant species were semi-shrubs from semimobile dune to mobile sand dune. Species number of Gramineae in the community was the highest dominant species in the semi-mobile sandy stage. Species number of Chenopodiaceae is stable after sandy sierozem. Species number of Compositae and Leguminosae disappeared or decreased continuously along the fixed and semi-fixed sand sandy succession gradient and their importance in community also decreased gradually. The species diversity was the highest in Sandy sierozem, and decreased then in fixed sand, and increased again in Mobile sand dune. Along with succession, the ecological dominance and species diversity which performed the opposite trend. However, the community evenness showed decreases firstly and then increased gradually again. There was a high degree of similarity between two adjacent communities along with succession. The content of clay silt reduced significantly , as well as soil particle fractal dimension in 0-10cm soil layer(P<0.01), but the content of gravel increased significantly. There was a significant negative correlation among annual herbaceous plants dominance, silt and clay soil and soil particle fractal dimension (P <0.05), while it showed a significant positive correlation (P <0.05) between Leguminosae dominance and silt, and soil fractal dimension, and then there was a significant positive correlation between species diversity and the content of silt (P <0.01), and had a significant positive correlation (P <0.05) between species diversity and fine sand content, soil fractal dimension.