Abstract:A preliminary study on hydrological effects of litter and soil layers in natural Pinus tabuliformis forest was carried out at four different altitudes(751, 890, 1 012 and 1 211 m) in the Songshan Mountains in Beijing City. Results showed that:(1) The total storage capacity, maximum water holding capacity and maximum water holding rate of litter increased firstly and then decreased with increasing altitude. (2) The total storage capacity of litter was about 9.03~27.75 t/hm². The maximum water holding capacity of litter was about 26.66~90.54 t/hm² and had a visible logarithmic correlation with immersion time(R>0.93). The maximum water holding rate of litter was about 287. 62%~296.73% and had a power relation with immersion time (R>0.99). (3) The soil bulk density decreased with increasing altitude in the range from 1.38 to 1.66 g/cm³. The total soil porosity decreased firstly and then increased with altitude. (4) The initial infiltration rates of soils were largely different and the steady infiltration rates varied from 1.95 to 7.06 mm/min. The infiltration rate had power function correlation with infiltration time(R>0.70). Generally, Pinus tabulaeformis forest at low altitude has a stronger water conservation function.

Abstract:As affected by the local topographical condition, soil moisture and thermal properties in the Daxingan Mountains varied largely, and soil types and vegetation in the region appeared to be the typical high-cold forest wetland with middle scale landscape feature. There were four types of soils from the local watershed divide to the low flood plain, i.e., sedge meadow soil, gray forest soil, Baijiang soil and dark brow forest soil. Obvious freeze-thaw process occurred in the forest wetland of the Daxingan Mountains, whereby the soil moisture content and phase varied significantly. Large soil moisture storage was observed merely in the surface horizon of forest soil in high relief during the freezing period, whereas obvious change in soil moisture content and phase was observed in the meadow soil in low relief. The water retention curve of Baijiang soil is very smooth, suggesting minor water change. The thin soil horizon developed in the mountain ridge and foot leads to a weak water retention capacity, except the litter layer(O horizon). When the litter layers are destroyed by human disturbances, serious soil erosion will occur.

Abstract:A new database was established, including the indexes such as different mycorrhizal types, net primary production(NPP) and average annual precipitation(MAP) of forests, based on the global forest database. The new database was used to study the responses of NPP of the forests to MAP change. Of all forests dominated by six different mycorrhizal types, the total NPP, aboveground NPP and tree leaf NPP increased with increasing MAP. However, the belowground NPP, stem NPP, and fine and coarse NPP presented a trend of either increase or decrease with the enhancement of MAP in the forests. As far as the responses of forest total NPP to MAP change concerned, the highest explanation(31.79%) of MAP change to the variation of total NPP was observed in the forest dominated by arbuscular mycorrhiza+ecto-mycorrhiza type. Contrarily, the MAP change only explained the 4.85% of the variation of total NPP in the forest dominated by ecto-mycorrhiza+ectendomycorrhiza type, which was the lowest explanation in all the six forests. We conclude that different mycorrhizas affect the extent of response of forest NPP to MAP change. Mycorrhizal type is an important index for accurate prediction of future change of forest NPP with change of precipitation.

Abstract:Spontaneous combustion of coal gangue hill is one of the main environmental pollution sources in mining area. To seal and afforest the coal gangue, a covering layer with a certain air barrier property is needed. The covering layer is made of soil materials by rolling compaction and thus the performance of air barrier depends on rolling quality. The compaction effect in relation to rolling tool and the rolling conditions of field coal gangue was studied by combining on-site compaction test for coal gangue dump governance in the Yangquan 3rd coal mine. Based on the rolling compaction experiment on the loess of various thicknesses, soil rigidity and dry density were measured to illustrate the rolling effect and the reasonable rolling parameters were analyzed under the condition that the degree of compaction(85%) was used as the compacted quality control standard. By utilizing the self-made grinding roller(4 t) for flat rolling, results show that shallow soil was more sensitive to rolling frequency in comparison with deep soil, and its corresponding depth was about 15-25 cm. The suggested construction proposal and rolling parameters are that moisture content is close to the optimum rate of water content (between±2%), loose paving thickness is 20-40 cm, and the material is compacted by 3~5 times rolling.

Abstract:It is an emerging measure of soil and water conservation to add polymers in soil. Clarifying its effects on soil erosion can provide a scientific basis for controlling soil erosion and selecting measures on loess slope. A simulated rainfall experiment was conducted to study the regulating effect of new chemical materials Jag C162 on infiltration on loess slope. Results showed that:(1) After dry spreading Jag C162, infiltration rate showed a decreasing trend with increasing rainfall time, whose decrease rate was less than bare soil. During rainfall, infiltration into bare soil reached a steady infiltration stage, while infiltration rate did not reach a steady state after dry spreading Jag C162. Initial runoff time was postponed correspondingly. (2) For the slope with different rainfall intensities and the rainfall intensity with different slopes, infiltration rate had significantly increased after dry spreading Jag C162. The stable infiltration rate of bare soil and average infiltration rate after dry spreading showed an increasing trend with increasing rainfall intensity and decreased with increasing slope. (3) Infiltration capacity for dry spreading Jag C162 was significantly higher than bare soil. With different doses, the infiltration capacity presented a general incremental trend with rainfall intensity increased, and infiltration capacity was decreased with slope increasing. (4) After dry spreading Jag C162, infiltration rate was increased and surface runoff and soil erosion were reduced.

Abstract:To examine unreasonable plantation and severe soil and water and soil loss on sloping land in Yunnan Province, a research was conducted on the benefits of soil and water conservation under sweet maize intercropped with green pepper and grass strip. In June, July and August, runoff under intercropping treatment decreased by 29.08% and soil erosion, by 52.36%, as compared with sole cropping; total runoff for the treatment B(sweet maize+grass) decreased by 85.05% as compared with the treatment D(green pepper mono-cropping), and total soil erosion, by 62.58% and 63.34%, respectively, as compared with the treatments C(sweet maize mono-cropping) and D; and during rainfall of the highest intensity, runoff for the treatment B decreased by 75.29% as compared with the treatment D and soil erosion decreased by 81.36% and 98.34%, respectively, as compared with treatment C and D. The result shows that sweet corn intercropped with grass strip is an effective measure for sustainable use and protection of soil and water resources in a mountainous area.

Abstract:In combination of field investigation with laboratory analysis, changes of plant community and soil characteristics were studied under different degrees of desertification in Yanchi desertification grassland to investigate the responses of vegetation and soil to desertification. Vegetation composition changes with the increased degree of grassland desertification. Perennial species gradually gave place to psammophyte annuals. Diversity index increased from mild desertification to moderate desertification grasslands. From moderate to extreme desertification grasslands, diversity index first decreased and then increased, which shows that the stage of moderate desertification is an important turning point for changes in plant community characteristics. Soil water content, organic matter and nitrogen content were reduced with increased sandy desertification on grassland; available P and available K content were the highest in extreme desertification stage, and changes of pH value and salt content did not show an obvious trend.

Abstract:Located in the Three Gorges Reservoir area, the Jinyun Mountains of Chongqing City is the national natural reserve. Due to the topographic characteristics, soil erosion and shallow landslides are easy to occur on slope. Therefore, effective disaster prevention without destroying original ecological environment is the key control work in this region. Pinus massoniana Lamb as Coniferous species and Gordonia acuminate as broad-leaf species, with the same root architecture, were selected, and their relative effects on the increment of soil shear strength were compared. Effects of crucial factors, e.g., root area ratio, shear zone root diameter level, spectrum of root position and angle distribution, on the shear strength were further discussed. Results show that the soil reinforcement effect for coniferous species was greater than those for broad-leaf species. The greater averaged tensile strength of coniferous tree led to a larger increment of soil shear strength. The coniferous species, presenting better steadiness on slope, had a larger spectrum of root position distribution and a greater amount of roots at an angle of 60° with shear direction. Effect of the root area ratio to soil shear strength is not notable.

Abstract:In order to understand the sandbag barrier's influence on sand flow and vegetation, wind speed, plant species, density, height and coverage were investigated through the ways of field testing and sampling. Transported sediment samples in 0-30 cm layer were collected and windbreak efficiency, surface roughness, transport rate and vegetation in 1 m×1 m, 2 m×2 m, 3 m×3 m sandbag barriers were studied. Results showed that sandbag barrier can improve wind efficiency and increase surface roughness effectively and meanwhile, wind efficiency and surface roughness were decreased with the sandbag barrier size increasing. Sandbag barrier sizes of 1 m×1 m, 2 m×2 m, 3 m×3 m had the different surface roughness values of 5.79, 2.38 and 2.12 cm that were 91.31%, 78.88% and 76.26% higher than CK, respectively. Sandbag barrier could effectively reduce sediment discharge which made sediment transport rate in every layer of 0-30 cm smaller than that of CK significantly. Compared with sediment transport rates for the three sandbag barrier sizes, the order was:1 m×1 m> 2 m×2 m> 3 m×3 m. After sandbag barriers were laid for 1 year, plant species of sandbag barrier was one more than that of CK, and the average height, density and coverage were 91.5%, 71.1% and 125.4% higher than that of CK. The average height, density and coverage of vegetation were increased with the sandbag barrier size increasing.

Abstract:Three kinds of herbs Vetiveria zizanioides, Pennisetum purpureum Schum and Miscanthus floridulus were selected for an experiment of soil and water conservation in the red soil hilly region of Southern China. Observations of soil physiochemical properties, runoff and soil erosion were made in runoff plots for nearly three years. Results show that compared with Vetiveria zizanioides and Pennisetum purpureum Schum, Miscanthus floridulus has obvious advantages on increasing surface coverage, improving soil physiochemical properties, reducing and retaining surface runoff, improving micro-landform, controlling and reducing soil erosion, and improving ecological environment. Furthermore, Miscanthus floridulus are widely distributed, the seeds can be obtained easily, and the cost of planting is very low. Therefore, Miscanthus floridulus is a good grass for soil and water conservation. Miscanthus floridulus should be selected firstly in projects of soil and water conservation in the ed soil hilly region of Southern China.

Abstract:Combined with the actual utilization of sloping farmland in the black soil area of Northeast China, surface runoff and soil loss from natural slope under natural rainfall condition were monitored and the benefits of soil and water conservation and their dominant driving factors were analyzed for three different soil tillage systems on 5° and 8° sloping farmlands of dark brown soil. Results showed that:(1) Surface runoff was greatly affected by soil tillage systems in corn field. These tillage systems were in the order of 8° ridged cross slope> 8° ridged cross slope with straw returning> 5° ridged cross slope> 5° ridged cross slope with straw returning> 8° ridged cross slope with straw returning and field bund with plants> 5° ridged cross slope with straw returning and field bund with plants. (2) The trends of runoff and sediment from different plots were similar, i.e., the more runoff, the larger sediment, but no line relationship appeared. (3) The largest runoff was found in the plot of 8° ridged cross slope. I₃₀ could be used to determine whether surface runoff occurred or not. There was 91% probability of runoff yielding when I₃₀ ≥ 6 mm/30 min, and the minimum rainfall for runoff yielding was 6 mm. (4) Rainfall intensity, not rainfall amount, greatly affected whether or not runoff occurred in the two plots of 8° and 5° ridged cross slope with straw returning and field bund with plants.

Abstract:Combing field investigation with laboratory analysis, we studied soil organic carbon(SOC) content in topsoil(0-20 cm) with different ages of the Stipa bungeana and Bothriochloa ischaemum grassland communities and presented the correlations of SOC content with geography, soil and vegetation characteristics of the communities in the loess hilly region, in order to proclaim soil carbon sequestration characteristics and notable influencing factors in the natural grassland restoration process. For the Stipa bungeana grassland, average SOC content dramaticlly increased from the 14 a to 18 a, with an average annual increment of 0.295 g/kg. The average SOC content gently increased first from the 18 a to 26 a, with an average annual increment of 0.186 g/kg, and then gradually decreased from the 26 to 45 a. The average SOC contents in 33 a and 45 a were 8.92% and 3.18% lower than that in the 25 a, respectively, but the difference was not significant. For the Bothriochloa ischaemum grassland, average SOC content gently increased from the 25 a to 40 a, with an average annual increment of 0.054 g/kg. The average SOC content obviously increased from the 40 a to 45 a, and the average SOC content in the 40 a was only 29.38% of that in the 45 a, and the difference was significant(p<0.05). SOC content in 0-10 cm soil layer was higher than that in 10-20 cm soil layer. Correlation analysis indicated that average SOC contents for Stipa bungeana and Bothriochloa ischaemum grasslands increased with the increases in restoration year, aboveground biomass, underground biomass and soil total nitrogen, and decreased with altitude and soil bulk density. Therefore, topsoils of Stipa bungeana and Bothriochloa ischaemum grasslands show the obvious function of carbon sequestration. Altitude, restoration year, aboveground biomass, underground biomass, soil total nitrogen and soil bulk density are the significant factors.

Abstract:The objective of this experiment is to study changes of antioxidant enzyme activity in Amorpha fruticosa L. Seedlings grown under combined drought and lead(Pb) stress. Pot experiment was carried out in a rain-proof shed to investigate the effects of drought stress(soil relative water contents were 100%, 80%, 60% and 40%), Pb stress(Pb contents were 0, 1000, 2000, 4000 and 6000 mg/kg), and the combined stress on the superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT) activities in the leaves of A. fruticosa L. seedlings. Results showed that SOD and CAT activities in the leaves of A. fruticosa L. seedlings first increased and then declined, but POD activity increased with the increase of the Pb content in soil under Pb stress. With the decrease of soil relative water content under drought stress, SOD and POD activities first increased and then declined, and CAT activity first declined and then increased. SOD and POD activities significantly increased under the combined drought and Pb stress, and CAT activity increased under the combined stress when the Pb content in soil was equal to or less than 2000 mg/kg. In conclusion, A. fruticosa L. seedlings have a strong tolerance to the combined effects of drought (soil relative water content≥40%) and Pb (Pb content≤2000 mg/kg) stress.

Abstract:A field experiment with two treatments, i.e. FI (flood irrigation) and BI (border irrigation), was designed and performed for the purpose of exploring a more effective irrigation mode based on traditional mode. The study was conducted to determine the effect of different irrigation modes on soil water content, soil water potential and vertical distribution characteristics of poplar root system and nitrate transport pattern in 0-100 cm soil layer. Results showed that BI decreased the soil water content and water potential in 0-40 and 60-100 cm layers with increased soil depth, indicating the weakened water deep seepage in the BI treatment. Root biomass decreased along with increased soil depth. Additionally, most of the roots concentrated in the 0-40 cm soil layer. Compared with the FI treatment, the BI treatment decreased root biomass in the 0-20 cm soil layer by 8.28%, whereas that in the 20-80 cm increased by 35.87%. Besides, the BI treatment increased the total root biomass in 0-80 cm soil layer by 5.52%, resulting in a higher extinction coefficient (β). As a result from BI, additionally, the nitrate content in 0-40 cm soil layer significantly increased, whereas that in 60-100 cm significantly decreased. Hence, border irrigation benefited the poplar root distribution. In conclusion, the BI treatment encouraged reasonable poplar root distribution, benefited water and nutrient absorption, and reduced nitrate leaching, which are important for the increased fertilizer use efficiency, environment protection and potential productivity of poplar.

Abstract:Soil evaporation (Es) is considered to be an important component of evapotranspiration (ET). In dry land of North China, the amount of water loss from soil through evaporation can take up to 50% or more of precipitation in the same period and during wheat growing season, evaporation can take up to 66% of field evapotranspiration. Research on soil evaporation and how to reduce soil evaporation is significant to find an approach to an efficient use of water resources. This preliminary study was conducted to examine the influences of different treatment measures on soil evaporation using a weighing lysimeter system. Results show that straw mulching and high stubble can restrain soil evaporation after irrigation when soil water content is high. In clear weather, soil evaporation intensity reaches the maximum at about 10:30 am, but straw mulching and high stubble can make it later. Loosing soil when soil water content is high cannot restrain soil evaporation, but it can significantly restrain soil evaporation when water content is reduced to a certain degree.

Abstract:Water conserving forest in the Laotudingzi Natural Reserve of Liaoning Province was investigated. Based on the important values of population, a study was performed to discuss the interspecific relationships among 16 main tree species by χ²-test, Ochiai association index, Pearson's correlation coefficient and Spearman's rank correlation coefficient. Results showed that the connection degree of most species-pairs did not reach a level of significance and the proportion of species-pairs which had highly significant or significant correlation was less, indicating that the interspecific relationships among forest tree species were loose and did not form a significant overall association, so the community was relatively stable. Compared with χ²-test, Ochiai association test and Pearson's correlation coefficient test, Spearman's rank correlation coefficient test was sensitive. According to the analysis results and combined with the tree species population biology and ecological adaptations, the 16 main tree species in the water conserving forest can be divided into three ecological species groups. The ecological requirements and resource use patterns of tree species within the same ecological species group are similar, exhibiting a close connection between the tree species and however, there is a loose coupling between different ecological species groups.

Abstract:Changes of soil factors and undergrowth vegetation species diversity indices, as well as their relationship, in the Eucalyptus industrial raw material forests of Yunnan Province are studied through filed investigation and laboratory analysis. Results show that species richness of herb layer is the highest, while Simpson index, Shannon-Wiener index and Evenness index of shrub layer are the highest. Meanwhile, soil moisture contents in different soil layers under the E. grandis×E. urophylla plantation show the order of parent material horizon> illuvial horizon> humus horizon. However, organic matter content, hydrolytic nitrogen, and available phosphorus and potassium decrease with depth and show the order of humus horizon> illuvial horizon> parent material horizon. Correlation analysis shows that species richness, biodiversity index and evenness index of shrub and grass layers are not significantly correlated with soil moisture and organic matter content in any soil layer. The K content of humus layer and Simpson diversity index of herb layer are significantly correlated. It is also true for the relationship between the K content of illuvial horizon and Simpson index of shrub layer. And there is a notable correlation between the N content and diversity index-based evenness index of shrub and herb layers. The soil factors of parent material and the diversity indices of herb and shrub layers are not correlated. The findings from the study may provide a theoretical basis and scientific evidences for the sustainable management of Eucalyptus industrial raw material forests.

Abstract:To explore the effects of conservation tillage on soil productivity, a field experiment with the five treatments of no-tillage with 20 cm(NS₂₀) and 40 cm(NS₄₀) standing stubble, no-tillage with 20 cm(NPS₂₀) and 40 cm(NPS₄₀) pressed stubble and conventional tillage, and conventional tillage(CT) were carried out to study the changes of soil organic matter(SOM), soil microbial biomass carbon(MBC), soil microbial biomass nitrogen(MBN), crop yield and water use efficiency(WUE) in the Heihe River Basin. Results showed that SOM, MBC and MBN in 0-20 cm soil layer under conservation tillage, which decreased with increasing soil depth under conservation tillage, were higher than that under CT. MBN significantly accumulated in surface soil under conservation tillage. Correlation analysis showed that MBC was remarkably correlated to SOM(r=0.85 and p<0.05), while there were no significant correlation between MBN and SOM(r=0.47 and p>0.05). Conservation tillage improved grain yield and WUE compared to CT. NPS₂₀ and NPS₄₀ had the best yield effects, increasing grain yield by 53.08% and 46.59% compared to CT, respectively. WUEs in NPS₂₀, NS₄₀, NPS₄₀ and NS₂₀ were increased by 58.02%, 43.40%, 47.27% and 23.78%, respectively.

Abstract:Populus allba and Calligonum mongolicunl farmland shelterbelt was planted in a moving sandy land outside newly reclaimed farmland in Hotan region. HOBO anemoscope, hygrograph, thermograph and sand sampler were set in the front and back of the shelterbelt, and the apparatus were conducted to determine the protection benefits of the farmland shelterbelt. The study was expected to provide a theoretical basis for building the outside protection forest and rationally exploiting and utilizing land resources in the deserted area. Results showed that wind-break potency of the shelterbelt decreased with the height. When wind velocity was greater than 6 m/s, wind-break potencies for the Populus alba belt and Calligonum mongolicunl belt at the height of 0.5 m were 67.2% and 94.5% and at the height of 3 m, 31% and 33%, respectively. Wind-break potency decreased with wind velocity and the Populus alba belt's effect was more obvious. Farmland shelterbelt played an important role in decreasing wind velocity and reducing wind erosion, and sand transportation in the shelterbelt was about 10% as compared with mobile sandy land. Besides, radiation and temperature were decreased, and humidity was increased sharply under the shelterbelt. Farmland shelterbelt plays an effective role in decreasing wind velocity, fixing mobile sandy land and optimizing the microclimate.

Abstract:The desertification combating areas around Qinghai Lake were selected in the study. The number and characteristics of soil microbe were examined through field survey and sampling and laboratory test. (1) The areas, in order of decreasing soil microbe gross, were semi-fixed dune in sand island, the lowland between sandy dunes in Ketu, shrubs in Ketu, shrubs in sand island, straw checkerboard barriers zone in Hudong sheep stud, mobile dune, straw checkerboard barriers zone planted with Hippophae thibetana Schlechtend. in Ketu, straw checkerboard barriers zone planted with Populus cathayana Rehd. in Ketu and straw checkerboard barriers zone recently set in the demonstration area. (2) In early combating areas, the vegetable coverage was high, the vertical distribution of soil microbe showed that the amount in topsoil(0-10 cm) was much more than subsoil layer(10-30 cm), and the content of soil microbe was richer than other sample plots. (3) In the mobile dunes and straw checkerboard barriers combating areas, soil microbe was very few, and its number in lower layer was a little higher than the upper layer, due to the better situation of soil water content in the lower layer of mobile dunes.

Abstract:Topsoil samples were collected from unmulched cropland, abandoned cropland and continuous watermelon cropland at different times. The samples were analyzed for soil microbial population and catalase, amylase, polyphenol oxidase and dehydrogenase activities. Then the dynamic characters of soil enzyme activities in crop growth period were studied. The soil microbial population of cropland with gravel-sand mulch was at a low level, the number of fungi decreased significantly, and both of the number of bacteria and actinomycetes in mulched cropland were between those in unmulched cropland and abandoned cropland. Dynamic characters of soil enzyme activities in different treatments were significantly different in crop growth period and however, most of soil enzyme activities reached a maximum value in vining stage or fruiting period. The crop growth and gravel-sand mulch had strong effects on soil enzyme activities. The results can provide a theory basis for the sustainable utilization and scientific management of the gravel-sand mulch cropland.

Abstract:In order to enhance the resources sharing among agriculture, forestry and animal husbandry and promote the development of ecological agriculture, researches on the change and interrelation of soil nutrients and the amount of microbes were separately conducted under six forest economy modes in Rongchang County, Chongqing City. Results show that soil nutrients were differently influenced by the under-forest economy modes. Organic matter and total potassium increased the largest in the raising poultry mode under Dendrocalamas, while total phosphorus increased the largest in the raising poultry mode under eucalyptus. Total nitrogen, available nitrogen and available potassium increased the largest in the raising poultry mode of Masson pine. In view of total microorganism biomass in soils, the poultry mode showed highest ratio in Eucalyptus, followed by the bacteria mode in Eucalyptus, and then the least one is bacteria mode in Dendrocalamas. The raising poultry mode under Dendrocalamas behaved the most, and the bacteria mode in Eucalyptus behaved the least in humus layers. The amount of microbes is directly correlated with the amounts of organic matter, available nitrogen and available phosphorus in soils. As the variation tendencies of soil nutrients and microbe quantity are different, the two should be combined in the study of under-forest economy processes.

Abstract:Choice of wetland use pattern to minimize the impacts on soil carbon fixation and CO₂ gas emission is the key for reasonable utilization of wetland and reduction of greenhouse gas emission. Wetland soil respiration is affected not only by environmental conditions, but also by soil traits. By a positioned experiment in Wanjing region, CO₂ emission flux, air temperature, surface soil temperature of soils in natural wetland and different reclaimed lands during the non-cropping season were measured and their soil TOC contents were analyzed. The land use types, in order of decreasing CO₂ emission flux, were paddy field[700.70 mg/(m²·h)], dry land[433.80 mg/(m²·h)] and natural wetland[302.66 mg/(m²·h)]. The soil TOC content of natural wetland was significantly higher than that of reclaimed dry land and paddy field (0-30 cm depth), indicating that the contribution of natural wetland to atmospheric CO₂ concentration was the lowest. Therefore, compared to dry land and paddy land, wetland is capable of storing more carbon. The correlation between CO₂ emission flux and temperature was also discussed. It follows from the discussion that CO₂ emission flux of the three land types is positively correlated with both of atmospheric temperature and surface soil temperature.

Abstract:In order to study soil quality of riparian zone in the upper reaches of the Hunhe River, a field investigation combined with laboratory analysis was employed to determine soil microbial quantity and enzyme activity characteristics of natural shrub grassland, secondary forest, artificial pine forest and corn field. The four vegetation riparian zones, in order of decreasing soil microbial quantity, were natural shrub grassland and secondary forest, artificial pine forest, and corn field. Bacteria occupied the most in the soil microbial groups, with proportions of 99.87%~99.94%. The activities of soil invertase, urease, phosphatase, polyphenol oxidase and catalase were 12.95~76.43 mg/(g·d), 0.35~1.80, 1.32~6.39, 0.35~1.61 mg/(g·d) and 0.93~3.27 ml/(g·20 min), respectively. The four riparian zones, in order of decreasing activities of the five soil enzymes, were natural shrub grassland and secondary forest, artificial pine forest, and corn field. By correlation analysis, the quantity of bacteria had a significantly positive correlation with the activities of the five enzymes, the quantity of actinomyces had a significantly positive correlation with the activities of the soil enzymes except hydrogen peroxide enzyme, and the quantity of fungi had significantly positive correlation with the activity of sucrase, phosphatase and polyphenol oxidase. In the four vegetation riparian zones, natural shrub grassland and secondary forest had the greatest microbial quantity, highest soil enzyme activity, and best soil quality and therefore, they are very good forms of riparian zone.

Abstract:A field experiment with three litter removed(10%, 50% and 70%) and four litter added(15% and 25% Bambusa intermedia, and 15% and 25% Cunninghamia lanceolata) treatments was conducted to study soil organic carbon in Dendrocalamus affinnis forest as affected by changeing litter input. Results showed that soil organic carbon content in the forest significantly decreased after litter was removed(p<0.05). The more the litter removed, the larger the decrease in soil organic carbon content was. Litter adding can significantly increase soil organic carbon content(p<0.05). Higher soil organic carbon content was detected in the 15% litter added treatment as compared with the 25% litter-added. Moreover, adding B. intermedia litter was more beneficial to soil carbon accumulation than adding C. lanceolata litter. This study suggests that the appropriate mixed species and proportion, as well as the protection of litter layer, can play important roles in maintaining soil organic carbon in D. affinnis forests.

Abstract:A pot experiment was conducted to determine the effects of four treatments, i.e., CK (neither urea nor vermicompost was applied), CF (100% of nitrogen was provided by urea), VC (100% of nitrogen was provided by vermicompost), and VC+CF (two 50% of nitrogen were provided by vermicompost and urea, respectively), on the soil microorganism population, enzyme activities, root construction and physiochemical properties in rhizosphere soil of poplar seedlings. Results showed that the VC+CF treatment was beneficial to coordinate the soil C/N ratio, and the application of inorganic fertilizer could supplement the consumption of nitrogen in the soil. Besides, the microorganism population and the activities of urease enzyme, catalase enzyme, polyphenol oxidase enzyme and invertase enzyme significantly increased. As compared with the CK, CF and VC treatments, the bacteria population in the VC+CF treatment increased by 165.99%, 67.34% and 31.73%, and the invertase enzyme increased by 90.37%, 45.31% and 32.34%, respectively. Vermicompost application had a beneficial effect on the fine root growth, and the aerial part was influenced by vermicompost greater than the under-ground part. Additionally, the VC+CF treatment obviously reduced soil pH value and significantly enhanced the efficiency of nutrient ions in the rhizosphere soil. Compared with the VC+CF treatment, the VC treatment had little effect on soil biological characteristics of one-year poplar seedlings. vermicompost co-applied with inorganic fertilizer had better effect on ecological environment in rhizosphere soil of poplar seedlings.

Abstract:Through field survey, systematic soil sample collection from surface soils and deep soil layers in the area, effects of land use type, altitude, slope degree and slope aspect on spatial distribution of soil organic matter are studied using variance analysis and buffer analysis methods. Results show that soil organic matter content on the two side areas is low overall, with an uneven distribution and large variability, and gradually declines with decreasing soil depth. Land use type, altitude, slope degree, slope aspect and the distance to the river have significant effects on soil organic matter only within 20 cm of soil surface. Land types, in order of decreasing organic matter content, are farmland, woodland, grassland and orchard wasteland. Organic matter content increases gradually with increasing altitude. Organic matter content on shady and semi-shady slopes is higher than that on sunny slope. Organic matter content increases away from the river bank, but gradually declines with increasing soil depth.

Abstract:Selection of covering materials on ground parking lot, as an important urban underlying surface, affects urban ecological environment. The study aimed at providing reference on the heat respect for the selection of ground parking lot's surface material. Based on the observed 12-month data of surface temperature, air temperature and direct solar radiation for four frequently-used surface materials, i.e., asphalt, cement, concrete ground brick and grass brick, the variation characteristics of surface and air temperature and their influencing factors were analyzed, and the analysis of the correlation between surface temperature and meteorological factors was made. Results show that:(1) The covering materials, in order of decreasing temperature, were asphalt, concrete ground brick, cement and grass brick. (2) The surface temperature had positive correlations with air temperature and direct solar radiation, of which air temperature makes more contribution. (3) Linear regression model about meteorological factors was established to provide a better theoretical support for the service of meteorology. The model can be used to calculate real time surface temperature.

Abstract:Evolutional characteristics of forest landscape structure and its internal driving mechanisms in Jinzhai County, Eastren Anhui Province from 1985 to 2011 were studied by taking TM images of 1986, 1996 and 2011 as data sources and using landscape indices analysis based on GIS and RS technology. Results showed that Jinzhai's woodland area continued to grow, arable land continued to decrease, and other landscape types increased or decreased by different amplitudes in the past 25 years. From 1986 to 1996, patch density, fractal dimension and Shannon evenness index changed negatively, the speed of landscape heterogeneity accelerated, and landscape pattern was in the severe situation of complex and fragmentation. From 1996 to 2011, after the "Grain for Green" project, the indicators changed positively, the situation of landscape fragmentation was effectively curbed, and landscape pattern turned to equalization and regularization. As a result, landscape structure has been optimized obviously. Natural geographical environment and the implementation of the "Grain for Green" project are the main driving forces for the formation of the evolutional characteristics of forest landscape pattern.

Abstract:The northeast black soil region, an important grain production area in China, is suffering from serious productivity degradation since long term conventional cultivation. It is helpful to develop an easy and practical productivity assessment method for black soil resources conservation. Soil samples were taken and analyzed for selected fields in the Hebei watershed, located in the north part of typical black soil region of Northeastern China. The quantitative relationship between top soil thickness and soil productivity was established and applied to assess soil productivity. Results showed that there was a logarithmic relationship between top soil thickness and soil productivity, which increased with increasing soil depth. However, the increasing rate varied and the rate was faster for soils at depth less than 40-50 cm than that at depth greater than 40-50 cm. Both long-term soybean yield and local land quality classing certified the rationality of the method, especially for assessing the spatial variation of soil productivity. In the studied watershed, tillage had significantly effects on the spatial distribution of soil productivity, which increased from slope top to toe generally. However, little variation existed within the field for contour cultivated fields, but obvious difference existed for up-down slope cultivated fields. It is necessary to practice conservation tillage.

Abstract:The land desertification characteristics in the kern oasis area of the lower Heihe River basin were analyzed using remote sensing image data with support of GIS technique. The studied results showed that desert area steadily increased in recent 20 years, reaching about 31 km²; saline-alkali land area was 465.97 km² in 2001, increased by 82.29 km² compared to 1990; and since the water transfer project was implemented in 2002, the saline-alkali land area started to decrease, but increased again in 2010. In recent 20 years, sandy land area steadily increased, but forest land and grassland area continuously decreased and their inter-conversion was frequent. Among different land cover types, the forest land, grassland, saline-alkali land, sandy land and water bodies varied greatly. Socioeconomic and population factors have a significant influence on the land desertification in the study region. Under the background condition of natural factors, the effects of human factors on the spatial-temporal distribution of water resources decide the evolution direction of the oasis in the study region.

Abstract:Based on long-time series data of annual runoff and sediment at key stations along the Xiangjing River from 1951 to 2011, evolution characteristics and laws of annual runoff and sediment were revealed by means of Mann-Kendall, wavelet analysis and average difference T methods, and its driving forces were analyzed. (1) The amount of annual runoff showed a slightly increasing trend and the amount of annual sediment, an obviously decreasing trend. (2) Temporally, runoff process did not show any mutation characteristic and annual sediment process, some mutation characteristics in 1997. After 1997, however, annual sediment declined significantly. (3) Wavelet analysis indicated periodicities of 20 years and 7 years for annual runoff and sediment processes, respectively. (4) The annual runoff series of the Xiangjing River can be divided into two plentiful phases of 1951-1954 and 1992-2002 and two drought phases of 1955-1991 and 2003-2011. Analyses of concentration ratio and period of annual runoff and sediment indicated that the inhomogeneity of inter-annual sediment distribution was more obvious than runoff, which mainly concentrated in June every year. (5) Significant reduction in annual sediment transportation was mainly contributed from sand controlling by water resource engineering and soil and water conservation engineering measures.

Abstract:Landslide developed under the unique environment of Western Sichuan Plateau is characterized by strong concealment and hence is a kind of extremely serious disaster because of its less evident sliding indication before occurrence. This kind of landslide often occurs suddenly due to freeze-thaw action, even in the absence of earthquake and rainfall, and then is transformed into debris flow. During its high speed movement, the landslide is capable of transporting and stripping loose materials on slope and therefore shows some movement and accumulation characteristics differing from common landslide by gravity. By taking the Zhaoma landslide in Zhongzhake Town, Dege County, for an example, development characteristics and failure process of the landslide are analyzed. According to the division and dynamic characteristics of landslide, its failure process is generalized as the three stages of gestation, high-speed movement and debris flow, and accumulation. Results show that the maximum movement speed of the Zhaoma landslide is as high as 75 m/s and intensive freeze-thaw action and the unique geological structure of the study area are the primary causes for its high-speed remote movement. Result from the study may provide a theoretical base for prevention and reduction of the landslide disaster induced by freeze-thaw action on the Western Sichuan Plateau.

Abstract:Due to irrational landuse, grassland has degraded severely and wind erosion occurs remarkably in recent years. By employing sand sampler and mobile wind tunnel, an observation for 6 years was made to analyze the mechanisms of wind erosion in Xilamuren grassland, the center of North Yinshan Mountains. Results show that:(1) Vegetation is the decisive factor for controlling wind erosion and the inhibiting effect of vegetation height on wind erosion is greater than that of vegetation coverage. (2) Wind erosion modulus in the initial period of enclosure reaches 1 313.7 t/(km²·a) and with the improvement of the grassland vegetation, wind erosion decreases year by year. (3) The deflation content gives priority to fine sand particles that account for more than 60%. For every 1000 kg soil eroded by wind, 15 kg organic matter, 227 g available nitrogen, 262 g available phosphorus and 120 g available potassium lose in the region at the same time, being a tremendous fertility loss. Therefore, the protection of base grassland and restoration of degraded grassland are two fundamental approaches to control wind erosion on the grassland.

Abstract:Northwest China lies in the Eurasia hinterland, which is one of the driest regions as compared with the areas in the same latitude. If drought persists, it will have a severe impact on social and economic development of the northwest region. Therefore, study of drought characteristics in Northwest China is of great significance to the eco-environment improvement and the promotion of economic development in the region. Standardized precipitation evapotranspiration index(SPEI) combining the influence of temperature on evapotranspiration is a new ideal indicator in the research on drought under the background of global warming. The data from 149 representative meteorological stations in Northwest China in 1959-2011 were used to analyze the temporal and spatial variation of drought. Results showed that drought was a universally existed fact in the northwest. From the inter-annual perspective, the region showed a drought trend with an abrupt change in 1996. Form the seasonal changes, the weather became drought in spring, summer and autumn, and had a humid tend in winter, which is not obvious. Worsening trend occurred in spring, summer and autumn, but was not obvious in winter. Spatially, most regions had a drought trend in spring and summer and a humid tend in winter. Compared with almanac data, SPEI, as a drought index, is confirmed to be applicable in Northwest China.

Abstract:Based on meteorological observation data from 1961 to 2012 at Huajialing, Anding and Tongwei stations and forest resources inventory data of Gansu Province, climate characteristics of the Huajialing over the past 50 years and its influences on the protective forest construction were analyzed using trend analysis and accumulative anomaly analysis methods. Results showed that decreasing rate of annual mean precipitation in the region over the past 50 years was -2.467 mm/a, increase rate of annual mean temperature was 0.024 2℃/a, and regional climate showed a typical development trend to warm and dry. Lack of precipitation was an important natural factor for the formation of inefficient protective forest in the Huajialing, while warm and dry climate change exacerbated adverse effects of arid climate on the local rainfed forestry and ecological environment construction.

Abstract:The study used remote sensing images and DEM data of 1985, 2000 and 2011 to calculate various factors for soil and water loss in the upstream area of East Wuliangsuhai coast based on GIS. Soil and water loss in the three years was classified according to the calculated result. A quantitative study was performed for temporal-spatial variations of soil and water loss area, as well as dynamic conversion of various types of soil erosion degree. Dynamic changes of soil and water loss were predicted with the Markov model. Results indicated that from 1985 to 2000 and 2000 to 2011, soil and water loss increased year by year. For 27 years, the slightly losing area decreased by 717.43 km², and the strongly losing area increased by 389.23 km². The intensified soil and water loss area mainly concentrated on East Wuliangsuhai coast, central pastoral area and sandy area. By contrast, soil and water loss gradually decreased in the regions of Ural Mountains, Serteng Mountains and Zhashitai Mountains. Predictably, from 2011 to 2022, the slightly and mildly losing areas will continue to decrease, and meanwhile the strongly and heavily strongly losing areas will increase accordingly. The evolution of soil and water loss in the upstream area of east Wuliangsuhai coast was fully discussed for better understanding of temporal-spatial variations of soil and water loss. The study provides a scientific basis for soil and water conservation and ecological construction.

Abstract:Debris flow is one of the most common geologic disasters in the southwest area of China, due to its tectonic structure position and unique topographic characteristics. Bengtuao debris flow, with strong mobility, is located in the diamond land block of Sichuan and Yunnan Provinces where is near the east fracture branch of the Anning River. Based on internal causes like topography, stratum lithological characters and neo-tectonic activity and external causes like rainstorm, characteristic indexes of the debris flow are obtained quantitatively in accordance with analyses of occurrence degree, activity patterns and hazarding ways, so that the definite controlling targets and project management program are put forward in detail. Most of debris flow disasters in this area occur on the same or similar geological background, especially the widely distributed Xigeda formation clay in the Anning River Basin, which are the main material source composition of debris flow and the governing factor and controlling object.

Abstract:Effects of different fertilization proportions of N and P on dry-land wheat yield in gully region of the Loess Plateau in the condition of normal rainfall were studied based on the long-term experiment in Changwu, Shaanxi Province. A trend surface model of dry-land wheat yield in the gully regions was constructed using trend surface analysis. Fertilization proportions for higher wheat yield were found and the fertilization proportions for the highest yield were N=178.169 kg/hm² and P=198.405 kg/hm². The maximum wheat yield was 6 152.6 kg/hm². Wheat yield with different N and P proportions in the condition of normal rainfall can be predicted by the trend surface model, which provides a theoretical basis for the actual agricultural production.

Abstract:Regarding the county territory units situated in 4 hydrologic basins as the research object, the paper explores the effects of arable land scale, the quantity and rate of non-agricultural arable land, and arable land non-agriculture on grain production in different research periods, from the two perspectives of county territory arable land and county territory arable land per capita in Henan Province. The main conclusions are as follows. Firstly, the scale and spatial distribution of arable land in the 4 hydrologic basins were associated with the area and landform of relevant hydrologic basins. Change trend and spatial pattern of county arable land in every basin were different. Secondly, change rates of arable land quantity in most of the counties were negative and concentrated in space in the former research period (1994-1999). However, change rates of arable land quantity in most of the counties were positive and dispersed in the space distraction in the latter research period (1999-2004). Thirdly, the quantity of county territory arable land per capita in four hydrologic basins was reduced, but the reduced amplitudes of arable land quantity per capita were different in the two research periods. Finally, arable land non-agriculture in the province and its four hydrologic basins were given priority to medium yielding field. Grain losses caused by arable land non-agriculture in the 4 hydrologic basins were great.

Abstract:Vegetation condition after implementation of the returning farmland to forest/grassland project in Huining County of Gansu Province was analyzed based on the analysis of MODIS NDVI data and field investigation in the study area. The vegetation conditions have been improved in recent years, with four facts as below:(1) Vegetation coverage has increased significantly due to the implementation of the project, closing hillsides for livestock grazing and other measures, and the area for increased NDVI index was 4404.75 km² in 2011 in comparison with the year of 2000, accounting for 77.74% of the total area of Huining County. (2) Vegetation type showed a stable and increasing tendency in the region after implementation of the project. (3) Soil erosion has been curbed, and the number of mountain torrents obviously decreased from 2000 to 2011, with the corresponding decline of discharge and destructive power. The average value for mountain torrents was 3 times for 50 drainage ditches in 2011, which declined by nearly half as compared with the case before the implementation of the project. (4) The majority of farmers have approved of soil and water conservation benefits after implementation of the project, and their economic income also showed an increasing trend.

Abstract:In view of the farmers' perceptions of climate change, we discuss the effectiveness or the lack of adaption behaviors which will be in a better position to provide scientific methods and decision-making on the district-level policies for combating climate change. According to the investigated data from 600 farmer households in Yutian County, Xinjiang Wei Autonomous Region, the article quantitatively analyzed the influencing factors on the farmers' perception and the preferences for the adapting behaviors of climate change by building the Heckman model. Results show that some variables have significant impacts on the farmers' perception of climate change, including the gender of householder, time length of engaging in agriculture, annual household net income, social networks, trust in information sources, nearness to water sources and climatic factors. Further, the variables such as the head of household gender, time length of engaging in agriculture, annual household net income, lending capacity, social networks, nearness to the water sources and climatic factors have significant impacts on the adapting behaviors. It is proposed that the local government must play a district-level leading role in the process of policy making and policy implementing. At the same time, the local government should make a variety of relevant policies to cultivate the farmers' self-development ability to combat climate change and ultimately achieve the comprehensively sustainable development of ecological, economy and society.

Abstract:The contradictions between resource and economic development have become increasingly prominent. Resource saving and its intensive use from the perspective of low carbon is a fundamental approach to enhance the ability of sustainable development. Taking Wuhan City as a study area, By literature referring method, the low-carbon perspective was combined with the land use characteristics of urban agglomeration to establish a sustainable land use evaluation index system. Integration of CSDEA(indicators coacervation) with entropy method was used to analyze each index value and get comprehensive evaluation result. An improvement program was obtained by further calculations. Results show that Huangshi, Huanggang, Xianning, Qianjiang Cities are relatively effective in the CSDEA of sustainable land use, while Xiantao, Tianmen, Xiaogan, Wuhan, Ezhou Cities are ineffective, with comprehensive evaluation values of 0.9849, 0.9791, 0.9725, 0.9574, 0.8082, respectively. The evaluation value is the lowest for Ezhou City that has nine big shortage indicators such as agricultural production. Indicators for Ezhou City needed to be reduced include the rural Engel coefficient, garbage transport volume and other five indicators, of which carbon emissions should be reduced to 97.33t/hm². Overall, Ezhou City should be greatly improved in sustainable land use. The evaluation results objectively reflect the status and lack of urban agglomerations land use and improvement program. In economic development, more attention should be paid to environmental protection and intensive and economical resource utilization and continuously improve the capacity for sustainable development.

Abstract:Taking Ciha Gorge as the research area and using GIS, the terrain factors such as altitude, slope, and aspect were extracted and overlaid with vegetation type map. Combined with indicators of diversity index(H), evenness(E) and others, the relationships between the spatial pattern of vegetation and the terrain factors were explored. Results showed that spatial vegetation pattern had a close relationship with terrain factors. The optimal growth range for subalpine dark coniferous forest on shady slope was in 3290~3880 m altitudes and 25°~45° slope degrees; for mountain Sabina chinensis forest on sunny slope, 3880~4470 m, the same slope degrees as on shady slope; and for coniferous and broad-leaved mixed forest and alpine deciduous broad-leaf forest, 2700~3290 m, 15°~25° on shady slope and 2995~3290 m on semi-shady slope, respectively. Alpine shrub and grassland had a relatively wide distribution in terms of slope degree and slope aspect.

Abstract:Based on GIS and RS, landuse variation features in the Shaanxi loess platform region from 1985 to 2010 were analyzed by a series of landuse change indexes. Results are as follows:In 2010, cultivated land, grassland and built-up land occupied 984 337.30, 143 030.47 and 105 871.35 hm², whose percentages over the total area of the loess platform region were 77.89%, 11.32% and 8.38%, respectively. During the research period, cultivated land, grassland, forestry land and water area decreased by 20 866.61, 11 065.22, 1 186.44 and 748.96 hm², respectively, accounting for 2.08%, 7.18%, 4.60% and 11.64% of each of land types in 1985, while built-up land increased by 33 902.8 hm², which took up 47.11% of built-up land in 1985. There were 26 668.8 hm² cultivated land changed into built-up land, accounting for 96.26% of the total area changed into built-up land, and 18 923.9 hm² grassland changed into cultivated land, accounting for 93.24% of the total area changed from grassland. The land system was relatively stable during 1985-1990 (synthetic dynamic index was 0.52), and the landuse change was active during 1990-1995 (synthetic dynamic index was 0.36). Since then, the synthetic dynamic index gradually decreased, the land system tended to be stable, and the value of synthetic dynamic index decreased to 1.16 from 2005 to 2010. In space, cultivated land changed into construction land was tremendously distributed around cities and towns, the mutual transformation between the cultivated land and grassland mainly occurred in the eastern part of Weinan platform region, the northern part of Xianyang and Baoji platform region.

Abstract:Based on the meteorological data of temperature and precipitation at 62 stations on the Tibetan Plateau from 1961 to 2008(date for the Pulan and Gaize Stations is from 1973 to 2011), the trend of snow disaster and its spatial characteristics were analyzed by using statistics and Kriging spatial analysis method. Results show that in the recent 51 years, the average of annual snow disasters increased and the number of station at which snow disaster occurred grew, especially after 1990. Snow disaster emerged mostly in early spring, secondly in former winter, and least in latter winter. The spatial distribution of snow disaster was uneven. Snow disaster occurred more frequently in the central plateau and southeastern plateau edge, in which higher frequencies of mild, moderate and heavy snow disasters were observed.

Abstract:This paper analyzed the correlations between normalized differential vegetation index (NDVI) and different climate indices (annual mean temperature, annual precipitation, aridity index, biological heat index and biological humidity index) in North China from 1982 to 2006. Results showed that temporal change of NDVI presented an overall upward trend, especially in farmland and bush land. Mean annual temperature and biological heat index increased significantly, while annual precipitation, aridity index and biological humidity index decreased. Overall, the NDVI was significantly negatively correlated with aridity index in corresponding period and positively correlated with temperature in previous period. The NDVI for grassland had a significantly positive correlation with mean annual temperature and precipitation and a most significantly negative correlation with aridity index. The NDVI for farmland and bush land was significantly positively correlated with mean annual temperature. In addition, there were significant spatial differences in the correlation between NDVI and climatic indices in North China.

Abstract:Based on Landsat TM images of 1990, 1999, 2006 and 2010, the oasis of Jiuquan-Jinta Basin was selected as a case to study the spatial and temporal variation of land use type and evaluate the ecosystem service value. Results showed that land use in the oasis of Jiuquan-Jinta Basin changed greatly between 1990 and 2010. The areas of farmland, forestland, grassland, urban and residential land increased gradually, while water area and unused land declined greatly. The ecosystem service value of oasis of Jiuquan-Jinta Basin was 2.453 billion RMB per year in 1990, 2.699 billion RMB per year in 1999, 2.984 billion RMB per year in 2006 and 3.016 billion RMB per year in 2010. Although performing a trend of gradual growth, its growth rate decreased by 10.04%, 10.54% and 1.09%, respectively. Analysis of single ecosystem service value showed that service value was greater than value of productivity. Change trend of ecosystem service value in the study area was in accordance with ecological risk index. Therefore, there is strong need for rational development and management of water and land resources to lower the ecological risk of oasis system and provide better service for sustainable development.

Abstract:Soil erosion has seriously affected black soil quality and food production in Northeast China. Based on GIS and RUSLE, a digital land-block map for decision making and management of soil erosion is made and the early warning and information decision making for erosion control with support of GIS is accomplished, by using remote sensing images, field sampling and farmer survey as data sources. Through this system, different control measures and suggestions can be provided according to erosion degrees in different land types, and digital management can be implemented for early warning of soil and water loss and decision making of soil and water conservation at field scale. In this way, information management model is established for comprehensive control of soil and water loss in Northeast China.

Abstract:In order to monitor the dynamic variation of vegetation in Qinghai Province, based on the MODIS-NDVI data from 2000 to 2009, characteristics of spatial and temporal variation were analyzed using statistical methods such as linear trend analysis and standard deviation. Results show that:(1) From 2000 to 2009, vegetation of the study area was improved progressively, with a linear tendency of 0.018/10 a which was faster than the growth rate of the Three North Shelter Forest Program(0.007/10 a) from 1982 to 2006. (2) Vegetation restoration experienced several stages, a rapid increase in vegetation coverage during the first five years of "Grain-for-Green" project and a significantly fluctuated decline after 2005. (3) Slight improvement(32.66%) accounted for the largest proportion of vegetation restoration, followed by moderate improvement(13.32%), and the significant improvement area was mainly distributed in the southeast edge of the Qaidam Basin, Qinghai Lake basin, Chaka-Gonghe basin, Hehuang Valley and the south Yellow River lowland. (4) The proportion of degradation tendency was 18.40%, which was distributed in the three rivers headwater and the eastern section of the Qilian Mountain. (5) Vegetation stability manifested significant regional difference, which was low in southeast and temperate zones, but high in northwest, frigid and sub-frigid zones. The changing magnitude was most obvious in the low mountains, hills and basins in eastern Qinghai Province.

Abstract:Rainfall and the concentrations and variations of total nitrogen (TN), nitrate, nitrite and N transformation in the headwater area of Taizi River watershed were studied by filed monitoring. Results showed that:(1) Rainfall from May to September in the watershed accounted for 81.8% of the total annual rainfall, which is the principal period for non-point source nitrogen output. (2) The mean concentration of TN had a waving trend in different monitoring sites. The landuse types, in order of decreasing TN content, were chicken farm, village, dry land and woodland, which was consistent with the soil background value. (3) From May 7th to June 10th, the early rainfall after a long term drought increased the TN content in dry land, village and chicken farm in comparison with rainy season. From June 10th to September 30th, TN content firstly decreased and then increased due to the increases in rainfall amount and frequency. In addition, the interaction of extraction and dilution caused by rainfall also increased the TN content. (4) The concentrations of nitrate and nitrite nitrogen in each site had a significant positive correlation with rainfall amount (p<0.05). Nitrate was the main form of total nitrogen output and accounted for about 69.2%, 63.4%, 61.4% and 63.8% of TN for woodland, dry land, village and chicken farm, respectively. Although vegetation cover had benefits in reducing soil erosion and the loss of TN, it increased the loss of soil soluble nitrogen.

Abstract:Using the temperature and precipitation data from 117 stations in the three-north shelter forest program areas from 1960 to 2011, we compared the characteristics of climate change in the areas before and after the implementation of the project. (1) Temperature in the project areas during the years showed a significantly increasing trend with a warming rate of 0.346°C/10 a. The years from 1960 to 1977 were a relatively low temperature period; temperature increased from 1978 to 1995; and the years from 1996 to 2011 were a significant warming period. The warming trend generally manifested the north-south difference, and the areas for notable increasing temperature mainly concentrated in northern regions such as Inner Mongolia Plateau, Songnen Plain in Heilongjiang Province and Plain of Western Jilin Province. (2) The annual precipitation of the project areas overall showed a declining trend with a decreasing rate of 3.554 mm/10 a. Precipitation was less than normal before the implementation of the project. In the beginning of implementation, there was a slight increase, but after 1996, precipitation performed an obviously decreasing trend. The tendency rate of precipitation distribution showed an apparent east-west difference. Precipitation in eastern regions decreased, while in western regions it showed a widespread increase and in eastern regions like Heilongjiang Songnen Plain and Inner Mongolia Yinshan Mountain area there was a notable increase of precipitation. (3) Spatial variation of climate change was obvious. The main climate changing trend in western regions like Altay Region and Qaidam Basin, and in the east regions of Inner Mongolia, Hetao Plain and Songnen Plain was warming and wetting, while in other regions, such as Hulun Buir prairie, Daxingan Mountains and Nenjiang Plain in Liaoning Province, the trend was warming and drying.

Abstract:In the improved index system, underground coal mining is chosen as the research object. Such conditions as natural environment, mining and coal mine occurrence constitute the constrained layer and eleven impact factors, such as terrain slope, land exploitation planning and coal seam thickness, constitute the index layer. Delphi and analytic hierarchy process (AHP) methods and YAAHP(V6.0)software are employed to determine the weight of each index. The weight comparison shows that in order of decreasing weight, the three compared conditions are the coal mine occurrence, mining and natural environment; the coal mine occurrence conditions are the coal seam thickness, dip angle of coal seam and ratio of crack depth; the mining conditions are the roof management method, coal mining technology and mining degree; and the natural environment conditions are the land exploitation planning, effective thickness of soil layer, precipitation, soil texture and slope of the terrain. The improved index system lays a foundation for determining the modified coefficient of the reclamation cost for the land destroyed by underground coal mining.

Abstract:The WXGEN weather generator is a component of the soil and water assessment tool (SWAT), which is applied as a hydrological model at catchment scale and applied to forecast weather condition and fill the missing weather data. This paper analyzes and assesses the precision of the daily and monthly weather data based on the comparison between the data simulated by the WXGEN and the daily observed data according to 5 national meteorological stations in the upper Yangtze River. Results indicate that the WXGEN generated data are generally in consistence with those from the five stations. The errors of daily data simulated by WXGEN are significant, while the monthly data are more accurate than those of daily data. In conclusion, WXGEN has better simulation of the distribution of monthly weather data and hence it is more suitable for the simulation of monthly weather data in the Upper Yangtze River. Yet the errors of the simulated monthly weather data demonstrate significant seasonal changes. The simulated monthly precipitation and temperature are lower than the observed values, while the average monthly solar radiation is above the observed value.

Abstract:According to the geological environment conditions of the study area and the characteristics of the Yun nickel tailing pond, population, assets and resources are selected as the evaluation indexes of geological disaster vulnerability. Delphi method and analytic hierarchy process (AHP) are used to determine the weight value of evaluation indexes and establish a generalized mathematical model. Using computer programming language C⁺⁺, combined with GIS system development platform for quantitative evaluation of vulnerability of geological disasters, this article gets graded partition map of geological disasters vulnerability. Geological disaster vulnerability of the Yun nickel tailing pond may be divided into the four grades of extreme vulnerability, high vulnerability, moderate vulnerability and low vulnerability. The research results not only provide a reference for studies of geological disaster vulnerability in other similar tailings, but also provide a scientific basis for regional planning and construction suitability evaluation by governments.

Abstract:The standardized precipitation index(SPI) was calculated based on monthly precipitation data observed at the nine weather stations in Ningxia Hui Autonomous Region from 1959 to 2011, and the spatial and temporal variation of drought was analyzed using the methods of drought station proportion, drought intensity, climate trending rate and the inverse distance weighted interpolation in ArcGIS. Results showed that annual SPI in Ningxia in recent 53 years decreased with an average rate of-0.131/10 a, which was the largest increase in the 21st century. As for the seasonal change of the SPI, drought in spring, summer and autumn was becoming heavier slightly, while in winter, it was becoming lighter. In view of the scope and drought intensity, the heavy drought expanded slightly in the study area, and yet the light and medium drought declined slightly both in scope and intensity. In the four seasons, drought intensity in winter increased slightly, but its scope shrunk; in spring, both drought intensity and scope increased; and in summer and autumn, drought intensity decreased and its scope shrunk. Continuous seasonal drought occurred from spring to autumn had the greatest impact on agricultural production. Spatial differences of annual and seasonal SPI were obvious. From north to south, drought was gradually aggravated, especially in the southern mountains, the most sensitive to change of regional drought.

Abstract:The sensitivity coefficients of daily reference evapotranspiration(ET₀) to average temperature, wind speed, relative humidity and sunshine hours in the Shiyang River basin during 1959-2011 were calculated by using Penman-Monteith equation recommended by FAO, based on daily meteorological data provided by the China Meteorological Administer. Moreover, temporal variations of the sensitivity coefficients were analyzed. Results show that relative humidity was the most sensitive factor of ET₀ in the Shiyang River basin, wind speed and temperature were in the second place, and sunshine hours had the lowest sensitivity. Because of climate factors contrast and significant spatial difference of the sensitive coefficients, the sensitive coefficient of relative humidity formed high value area in the upstream area of the Qilian Mountains. Meanwhile, the sensitive coefficient of temperature was relatively large. But the sensitive coefficient of wind speed was the largest in the downstream area of the Minqin basin. The sensitive coefficient of sunshine hours had no significant difference in all the areas. The sensitive coefficient of each of the meteorological factors showed a certain degree of volatility. Wind speed was high in winter, but low in summer; temperature and sunshine hours were all high in summer; and the absolute value of relative humidity continued to rise to the maximum in fall. The sensitive coefficient of relative humidity fluctuated in the past 53 years, absolute value showed a significant upward trend, but the wind speed, sunshine hours and temperature had no obvious trend in the last 20 years.

Abstract:Effect of CCS technology for CO₂ leakage on C₄ crops seed germination is simulated so as to provide basic information for the potential effect of CCS technology for CO₂ leakage on environment. With the help of artificial CO₂ climate chamber, the impacts of CO₂ on the percentage, potential and the average days of germination of 4 C₄ corps like corn, sorghum, millet and broom corn millet were studied under the condition of normal, 10000, 20000, 40000, and 80000 mg/kg CO₂ concentration by simulating the environment of high CO₂ concentration resulted from CCS technology for CO₂ leakage. The high CO₂ concentration has little effect on germination percentage of corn, while the germination percentages of sorghum, millet and broom corn millet reach the maximum values at 10000, 20000, 20000 mg/kg CO₂ concentration, respectively. High CO₂ concentration also has no significant impact on the germination potential of corn, while all the germination potentials of sorghum, millet and broom corn millet reach the maximum values in 20000 mg/kg CO₂. High CO₂ concentration has little effect on the average germination days of four kinds of C₄ crop, in which the effect toward broom corn millet is more significant than others. Various CO₂ concentrations have the functions of promotion and inhibition toward the germinating percentage of C₄ corps and however, the effect is not very obvious, in which the promotion range is about 1%~5% and the inhibition range is about 1%~4%. High concentration CO₂ plays more significant role in promoting C₄ crop seed germination potential, in which the promoting range is 9%~16%. High CO₂ concentration has little effect on the average germination days of four kinds of C₄ crop.

Abstract:Disaster-pregnant environment and watershed morphology are the base of the development and activity of debris flows and therefore, clearly recognizing the disaster-pregnant environment and watershed morphology characteristics has an important realistic meaning to disaster prevention and mitigation. Based on the analysis of the spatial distribution patterns of debris flows in the Bailong River basin, a further study of the characteristics of the disaster-pregnant environment is made from the aspects of regional tectonic environment, topography and geomorphology, formation lithology, precipitation and so on. The coupling relationships between these factors and debris flow distribution are explored. Meanwhile, as to 250 debris flow gullies along the mainstream of the Bailong River, the basin area, length of the main gully, relative relief of debris flow gully and other important parameters are analyzed using mathematical statistics, and the characteristics of basin form in relation to debris flows along the mainstream are identified.

Abstract:In order to define soil type in the main tobacco producing areas of Shaanxi Province, this study selected three typical soil profiles in the suitable planting areas(Luonan, Longxian and Xunyang Counties) and separately carried out field observation and indoor test to collect basic soil physical and chemical properties in each horizon. Based on the study of the formation conditions and characteristics of soil samples, the diagnostic horizon and diagnostic characteristics of each soil sample were characterized, as well as the identification in Chinese soil taxonomy system, according to the Chinese Soil Taxonomy(3rd edition). Results show that the identifications of the profiles are typic Ferri-udic Argosols in Luonan County, typic Calci-ustic Isohumosols in Longxian County and typic Hapli-udic Argosols in Xunyang County. In order to facilitate the extension and utilization of soil taxonomy system in the Shaanxi tobacco planting areas and provide scientific basis for soil planning in the Shaanxi tobacco planting base and international academic communication, comparison between Chinese soil taxonomy and Chinese genetic soil classification was made.

Abstract:Soil moisture plays an important role in arid ecological system, and soil moisture content is an important parameter in determining soil drought. We analyzed the relationship between the spectral characteristic parameters of emissivity and the soil moisture content that were measured in field and laboratory, and extracted the best sensitive band of inversed soil moisture content by the parameters from spectral characteristic analysis. it was found that the wave length were in 9.480 2~9.7901 μm and the soil moisture content was the most sensitive to its emissivity. Based on the scope of the most optimal sensitive waveband, the thermal infrared wavebands of MODIS, ASTER and HJ-1B Satellites were simulated, a regression analysis was made for waveband, waveband ratio and soil moisture content, and a linear model of waveband ratio was ultimately constructed, which can effectively deduce soil moisture content. The model was verified so as to find the linear relation of soil moisture content with the emissivity of thermal infrared bands 12 to 14 (simulated ASTER satellite sensor). The inversion is so precise that an inversion model applicable to the relation of infrared emissivity and soil moisture content in the studied area was established.

Abstract:The areal data for each type of natural vegetation in 1987, 2000 and 2010 in the Shiyang River Basin were obtained using remote sensing method with the aid of ArcGIS 9.3 software statistics. Accordingly, the ecological water requirements of natural vegetation in different counties and areas of the basin were estimated. By using Avi Lubyanka estimation method, it turned out that the suitable ecological water requirements for natural vegetation was 2.43, 2.34, 2.06 billion m³ in 1987, 2000 and 2010, respectively. The counties, in order of decreasing water requirement, were Sunan County, Tianzhu County, Yongchang County, Minqin County, Gulang County, Liangzhou area and Jinchuan area. The ecological water requirement for each of woodland and grassland in the basin basically took up half the total water demand. However, it is obvious that there was a sharply different percentage for the ecological water requirements of woodland and grassland in different areas, and the water using efficiencies of natural vegetation were between 2.74 and 16.55 kg/(hm²·mm). Through the study of the ecological water requirements of nature vegetation in three different periods, it is found that the water requirement of nature vegetation showed a decreasing trend both in the total water requirement and the coverage degree of natural vegetation. So the determination of the suitable ecological water requirement for natural vegetation has a significant meaning to the rational allocation of water resources and the scientific schemes worked out for ecological restoration.

Abstract:The control and protection of urban riparian wetlands have great significance for urban ecological environment, and monitoring vegetation coverage is an important way to study wetland vegetation conditions. By taking the Yellow River wetlands in Zhengzhou City as the study area, the equal density model was used to inverse wetland vegetation coverage based on the TM remote sensing images of the Yellow River wetland between 1999 and 2011. Combined with precipitation data and field survey, vegetation coverage changes in the wetland were analyzed. The ecological environment in the wetland was fragile; the average vegetation coverage decreased from 60% to 40% during the study period; and typical vegetation of the Yellow River wetland has been destroyed. Differences in precipitation obviously impacted vegetation coverage, while more and more human activities were an important factor leading to continuous reduction of vegetation. Result from the study may serve for regional ecological restoration planning and enhance the ecological and economic values of the Yellow River wetland.