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Search Results: 1 - 10 of 29027 matches for " XIE Fu-Ti "
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Diurnal variations of soil evaporation δ18O and factors affecting it in cropland in North China

YANG Bin,XIE Fu-Ti,WEN Xue-Fa,SUN Xiao-Min,WANG Jian-Lin,

植物生态学报 , 2012,
Abstract: Aims The δ18O of soil evaporation (δE) is an important factor controlling the variations of atmospheric δ18O (δv), and it is also one of the key challenges of partitioning evapotranspiration into evaporation and transpiration components. δE is mostly simulated by the Craig-Gordon model, which is constrained by the δv of water vapor, the relative humidity (h), the equilibrium and kinetic factors and the δ18O of soil water (δs) at the evaporating front. Our objective is to investigate the diurnal variations of δE and factors affecting it. Methods We determined the δ18O of water vapor in a winter wheat-summer maize cropland based on the in-situ and continuous water vapor isotope ratio measurement system. We sampled soil water at different depths and analyzed it using the cryogenic vacuum distillation technique to acquire the δ18O of soil water at the evaporating front. Important findings During the growing period of winter wheat-summer maize, the diurnal variation of δE exhibited a bimodal pattern with peaks at 6:00 and 15:00. The h has a significant effect on the diurnal variation of δE in cropland ecosystems, and causes the Craig-Gordon model to be invalid under high humidity condition of h>95%. The in-situ and high resolution measurement of δv overcomes the uncertainty of using the local precipitation equilibrium method to evaluate δv, which improves the accuracy of δE. Different equilibrium factors have no significant influence on the accuracy of δE. Different kinetic factors, especially the canopy scale kinetic factor, influence the accuracy of δE significantly. The location of the evaporating front determines the h normalized to soil temperature and the δ18O of soil water directly and also influences the accuracy of δE significantly. Further research is needed to attain direct measurement of δE by combining isotope ratio infrared spectroscopy (IRIS) with the static chamber or dynamic chamber.
The Elastic and Thermodynamic Properties of Hafnium Nitride
LIU Fu-ti,CHENG Xiao-hong
Journal of Chongqing Normal University , 2012,
Abstract: The geometry structure of Hafnium Nitride was optimized by the first-principle plane-wave density functional theory super-soft pseudo-potential method, we obtained the lattice parameter which consistent with experiment. The elastic constants were calculated under 0 up to 150GPa pressure. The result show the structure is stable. Then through the quasi-harmonic Debye model, the thermodynamic properties of HfN was obtained in the temperature from 0 to 2 200K and pressure from 0 to 150 GPa. The heat capacity, thermal expansion coefficient and entropy are increasing with the rise of temperature or the decrease of pressure. Debye temperature is decreasing with the rise of temperature or the decrease of pressure.
Studies of Soil Seed Banks of Representative Karst Mountainous Region in Three Gorges Reservoir Region--Based on Chongqing Municipality
LI Yang-bing,XIE De-ti,WEI Chao-fu
Journal of Chongqing Normal University , 2009,
Abstract: In the use of method of "Replacing time by space", on the analysis of species composition, amount and distribution, ecological dominance as well as species similarity, and diversity, the properties of soil seed banks of different land use system located in different ecological evolution sequence, including natural forest, secondary forest, shrub grassland, cropland, artificial woodland, abandoned dry field are studied in Beibei, Wushan, Qianjiang and Jifo Mountain of Nanchuan. They are the representative karst mountainous region of the Three Gorges Reservoir region within Chongqing municipality. The results show that 68 species germinated in all of 24 plots. Most seeds in different land use system soil seed banks are herbage species, and have a abvious connection with above vegetations, indicating that vegetations are at the early stages of succession and serious degradation. The amount of seeds of xylophyta species decreased and that of herbaceous species dominated by farmland weeds have increased with the increase of land use intensity. The geographical compositions of herbaceous plants of thrub-grass plot's soil seed bank indicate that genera of cosmopolitan have a heavy percentage, indicating that the growth of herbaceous layer is affected significantly by human being's activities. Therefore, it is important to preserve rare tree species in existing karst vegetation for improving the karst thrub grass land's evolution successively. From abandoned cropland, shrub-grass land to secondary forest land ,the ecological dominance has declined and the diversity and richness indices have increased. After the karst slope being cultivated, the soil seed banks of it have been destroyed soon. Therefore, the changes of land use pattern are the main threat to the karst secondary vegetation and the soil need banks in Three Gorges reservoir region.
Land use change and its socio-economic driving forces in Dahong River Reservoir area

SHAO Jing-an,LI Yang-bing,WEI Chao-fu,XIE De-ti,

生态学杂志 , 2007,
Abstract: Based on the interview with farm households and the land use and socio-economic survey, this paper analyzed the land use change and its driving forces in Linshui reservoir area of Dahong River Reservoir constructed in the 1950s. The results showed that the land use change in this area was mainly represented in low-lying land submergence and migration requisition. The former changed the land use pattern, while the latter reconstructed the original land property and made the land over-fragmented. The cultivated land per capita was 0.041 hm2, which was below the cordon of cultivated land per capita enacted by the Food and Agriculture Organization of United Nations (FAO). Up to now, there were still 30.25% of farm households being short of grain in trimester of one year, and 35.27% of the people still lived under poverty line. The eco-environment in this area was quite poor, and the healthy and sub-healthy eco-environment only occupied a small proportion, which was composed of the shelterbelts around the reservoir and the paddy fields, economic forests and orchards. Rapid population increase was the key factor inducing the change of man-land relationships in the area, and the low level of rural economy was the crucial factor deciding the decision-making of production by the emigrants. The belief of emigrants affected the land use patterns in a certain extent, and was the inducing factor of keeping land use whether stable or not.
Effects of conservation tillage on soil organic matter in paddy rice cultivation

SHAO Jing-An,TANG Xiao-Hong,WEI Chao-Fu,XIE De-Ti,

生态学报 , 2007,
Abstract: In this study, the effect of conservation tillage on soil organic matter (SOM) in paddy rice cultivation after 10 yr was investigated. Four treatments, disk till-fallow (DTF), disk till-wheat (DTW), conservation till-fallow (CTF) and conservation till-wheat (CTW) were used. The results indicated that the combinative application of no tillage, ridge culture and wheat cultivation was a sound conservation practice in paddy rice cultivation. It not only significantly increased the concentration of SOM in the topsoil, but also further affected humic acids (HA) optical and pyrolysis characteristics through changing the composition and structure of SOM. At 0-10 cm, the greatest SOM content was in CTW, but declined sharply with depth, while in DTF, DTW and CTF was not as high at the surface as in CTW, but the SOM content did not decline as fast as in CTW. The oxidation stabilization of SOM was generally greater in no tillage and ridge culture than that of disk till. The HA optical density in CTW at wavelength 665 nm and 465 nm was 0.122 and 0.705, while in DTF was 0.062 and 0.321, respectively. E4/E6 ratios in CTW were higher than that of in the other treatments. The enthalpy capacity of exothermal peak (360-365 ℃) for HA DTA curve in no tillage and ridge culture was lower than that of in disk till, while the HA absorption peaks in 1000-1050 cm-1 presented the reverse trend. The oxidation stabilization coefficient of HA in no tillage and ridge culture was higher than those in disk till, indicating that polycondensation degree and aromatization of HA were stronger. Those findings suggest that it may be possible to manipulate paddy soils through conservational tillage and crop practices and thereby maintain adequate SOM concentrations, mitigate soil organic carbon loss from soil to atmosphere.
Farmers'' explanations of land transfer under the household responsibility system: The results from seven villages'' analysis in Chongqing

SHAO Jing-an,WEI Chao-fu,XIE De-ti,

地理研究 , 2007,
Abstract: Using a large data set gathered in household surveys conducted in Chongqing from December,2003 to April,2005,this paper examines some important aspects of agricultural land use under household responsibility system(HRS).The results indicate that the general trend is that the rate of land transfer is higher in the Yuxi economic corridor than in the metropolitan area,which,in turn,has a higher transfer rate than the Three-Gorges economic zone.Gradually,the mode of subcontracting has been accepted and adopted by the local farmers,and the modes of land renting and alienation in exchange of cash are beginning to appeal to some of the households.Land renting or leasing,is the chief form of land transfer in the metropolitan area,while most farm households in the Yuxi economic corridor and the Three-Gorges economic zone prefer the form of subcontracting,which does not terminate the original contract relations.The responses of land use patterns and land use environment to land transfer are noticeable in the sampling villages.Most of the transferred farmland in the metropolitan area is allotted to non-agricultural uses.In the Yuxi economic corridor and the Three-Gorges economic zone,only a small portion of the transferred land is used for non-agricultural uses and the intensiveness of land use is enhanced for most of it without major changes in land cover.The conditions of land tenure control the scope of land transfer without great inter-regional variation.The degree of development of the rural land market not only impacts the scope of land transfer in the region,but also constitutes the fundamental causes for the inter-regional variation in land transfer scope and in the evolution of transfer modes.Social security plays a decisive role in whether the farmers are willing to quit farming and in what way they will quit farming.Management of land transfer,which includes rights security management and land use management after the transfer,is essential for standardizing the behavior of the principal agents in land transfer,for reducing disputes in transfer and ensuring the smooth proceeding of land transfer according to law.Understanding the psychology of the farm households under the changing macroeconomic environment and their responses to the driving factors for land transfer is of tremendous significance to the establishment of a market law-abiding and human-oriented system for land transfer in China.
The Relationships between Farm Household''''s Income and Land Management Practices in Citrus Industrial Zone of Three-Gorgers'''' Reservoir Area

SHAO Jing-an,LI Yang-bing,WEI Chao-fu,XIE De-ti,

资源科学 , 2007,
Abstract: Three-Gorgers Reservoir Area is very suitable for citrus growth.Nowadays,it has been some scales in citrus production.The citrus can protect soil and water from loss,and has lower demand to relief conditions,compared to the other crops.Citrus,being one of the most important industries is the result of the coupling between natural select and farm household's behaviors.This study,using primary data covering a cross-section citrus growers involving Changsha of Kaixian,Zhuyi of Fengjie and 30 citrus gardens,examines the relationship between farm household's income and land management practices in citrus industrial zone of Three-Gorgers Reservoir Area,where citrus is the main competitor for land use.The results indicated that the scales of citrus plants induced the different inputs of land management practices,and resulted in the differentiation of farm household's income.In Changsha of Kaixian and Zhuyi of Fengjie,the income of citrus increased 9.25% and 10.52%,when the scales of citrus plants enhancing 1%.Under the different scales of citrus plants,farm households have different demand for technologies in terms of management of citrus gardens,fertilizing, irrigation,and control of diseases and pests.Thus,these lead to the difference in yield,quality and price of citrus.Farm household increasingly attended technique training and consultation,following the expansion of citrus plant scale.Farmers,possessing a number of citrus,presented strong aspiration for technologies.The scales of citrus determined the yield,which in turn the yield of citrus affected the farm household's income.However,the ratio of the income resulting from citrus to farm household's total income determined farm household's attitudes toward citrus,and further affected the additional inputs of farm household land management practices.The differences of land management practices among farm households,in turn,influenced the yield and quality of citrus,and further presented significant differences among farm household's income.Land management practices have played more primary roles in farm household's behaviors,and been critical factors determining their income.It is suggested that it is possible to provide micro-practical foundation for the industrialized production of citrus and corresponding inputs on land management practices,and to apply ground information for reconstructing appropriate strategy of citrus growth.
Response of CH4 emission of paddy fields to land management practices at a microcosmic cultivation scale in China
SHAO Jing-an,HUANG Xue-xi,GAO Ming,WEI Chao-fu,XIE De-ti,CAI Zu-cong,
SHAO Jing-an
,HUANG Xue-xi,GAO Ming,WEI Chao-fu,XIE De-ti,CAI Zu-cong

环境科学学报(英文版) , 2005,
Abstract: The terrestrial ecosystem may be either a source or a sink of CH_4 in rice paddies, depending, to a great extent, on the change of ecosystem types and land use patterns. CH_4 emission fluxes from paddy fields under 4 cultivation patterns (conventional plain culture of rice(T1), no-tillage and ridge culture of rice(T2), no-tillage and ridge culture of rice and wheat (T3), and rice-wheat rotation(T4)) were measured with the closed chamber technique in 1996 and 1998 in Chongqing, China. The results showed that differences existed in CH_4 emission from paddy fields under these land management practices. In 1996 and 1998, CH_4 emission was 71 48% and 78 82%(T2), 65 93% and 57 18%(T3), and 61 53% and 34 22%(T4) of that in T1 during the rice growing season. During the non-rice growing season, CH_4 emission from rice fields was 76 23% in T2 and 38 69% in T1 The accumulated annual CH_4 emission in T2, T3 and T4 in 1996 decreased by 33 53%, 63 30% and 65 73%, respectively, as compared with that in T1 In 1998, the accumulated annual CH_4 emission in T1, T2, T3 and T4 was 116 96 g/m~2, 68 44 g/m~2, 19 70 g/m~2 and 11 80 g/m~2, respectively. Changes in soil physical and chemical properties, in thermal and moisture conditions in the soil and in rice plant growth induced by different land use patterns were the dominant causes for the difference in CH_4 emission observed. The relative contribution of various influencing factors to CH_4 emission from paddy fields differed significantly under different land use patterns. However, the general trend was that chlorophyll content in rice leaves, air temperature and temperature at the 5 cm soil layer play a major role in CH_4 emission from paddy fields and the effects of illumination, relative humidity and water layer depth in the paddy field and CH_4 concentration in the crop canopy were relatively non-significant. Such conservative land use patterns as no-tillage and ridge culture of rice with or without rotation with wheat are thought to be beneficial to reducing CH_4 emission from paddy fields and are, therefore, recommended as a significant solution to the problems of global(climatic) change.
Pedodiversity in karst area of Chongqing, China

SHAO Jing-An,LI Yang-Bing,MENG Yue-Ling,WEI Chao-Fu,XIE De-Ti,

生态学报 , 2007,
Abstract: Different soil types figure the heterogeneities of soil landscape patterns. However, land use practices that exert on different soil types reconstruct original soil landscape patterns. The objective of this study is to identify the landscape characteristics of pedodiversity in karst area of Chongqing, China, using landscape indicators. The results indicated that the diversities of soil landscape and its spatial heterogeneities were very lower in karst area of Chongqing. The distributions of every soil landscape were not average. The mosaic patch of soil landscape presented complex geological shape. Yellow soil, limestone soil and yellow brown earth were primary soil types in karst area of Chongqing. There were mainly woodland and grassland landscape in mountain meadow soil, and woodland landscape in brown earth. The rest soil types possessed mostly cropland and woodland landscape. Cropland and woodland played more important role in the structure and function of spatial landscape patterns in karst area of Chongqing. Nevertheless, the ratio of cropland and woodland to each soil types occurred pronounced differences due to soil properties and soil distributions, respectively. Human activities induced the rapid increase of mosaic patch of cropland, and the augment of mosaic patch of residential and mining land, woodland,unused land as well. This study would supply information for land use decision-making, and deepen the understanding of pedodiversity in karst area.
Strategies for poverty reduction and eco-environmental sustainability in old reservoir regions: A case study of Linshui Reservoir in Sichuan Province
老库区反贫困与生态环境的可持续性 ——以四川省大洪河水库邻水县库区为例

QU Ming,NI Jiu-Pai,PEN Jing-Yun,WEI Chao-Fu,XIE De-Ti,

生态学报 , 2006,
Abstract: Reservoirs built and financed by the Government in(1950's1970's) contributed enormously to the national macroeconomic development and local people's livelihood during that period.However,the construction of those reservoirs has deteriorated the natural environment and resource supply,leading to massive poverty in associated regions that occurs today.Furthermore,the insufficient migrant aftercare and governmental subsidies have made it difficult for locals to rebuild their lives.Therefore,to reduce the poverty in those regions we need to develop integrated strategies to transform the current social,economical and ecological structures to a manageable and sustainable establishment.As a case study,we analyzed the problems related to the poverty and eco-environmental sustainability in the Linshui Reservoir Region of Sichuan Province and established a sustainable development model using the uncertainty multi-objective planning framework.The results showed that to achieve the objective for the poverty reduction and eco-environmental improvement it was necessary to emigrate 8711 people,and establish 3188.24 hm~2 terrace,85.47hm~2 artificial grassland and 1413.07hm~2 economic forests and orchards.The prediction provides an optimal land use structure at the regional level that could not only improve the eco-environment,but also allow locals to have sustainable economical gain.We believe that these strategies can be the key measures for poverty reduction and environmental improvement in all 'old reservoir' regions.
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