检索结果-南通市图书馆

Analyzing Forest Effects on Runoff and Sediment Production Using Leaf Area Index

在线全文

学校读者我要写书评

暂无评论

Journal of Mountain Science 2014年第1期11卷 119-130页

作者： WU Xiao-Xia GU Zhu-Jun LUO Hao shi xue-zheng YU Dong-Sheng School of Bio-Chemical and Environmental Engineering Nanjing Xiaozhuang University Institute of Hydro-geophysical Prospecting Chongqing Research Institute of China Coal Technology & Engineering Group Corporation State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of Sciences

Quantifying the effects of forests on water and soil conservation helps further understanding of ecological functions and improving vegetation reconstruction in water-eroded *** on the effects of vegetation on water and soil conservation have generally focused on vegetation types or vegetation horizontal distribution ***,only a few studies have used indicators that consider the vegetation vertical *** study used the leaf area index(LAI) to investigate the relationship between forests and water and soil conservation in experimental *** 2007 to 2010,rainfall characteristics,LAI,and water and soil loss in 144 natural erosive rainfall events were measured from five pure tree plots(Pinus massoniana).These tree plots were located in Hetian Town,Changting County,Fujian Province,which is a typical water-eroded area in Southern *** polynomial regression models for LAI and water/soil conservation effects(RE/SE) were established for each *** RE and SE corresponded to the ratios of the runoff depth(RD) and the soil loss(SL) of each pure tree plot to those of the control plot under each rainfall *** transformation LAIs of the LAI–RE and LAI–SE curves,as well as the rainfall characteristics for the different water/soil conservation effects,were *** increasing LAI resulted in descending,descending–ascending,ascending–descending,and ascending trends in the LAI–RE and LAI–SE *** rainfall frequencies corresponding to each trend of LAI–RE and LAI–SE were different,and the rainfall distributions were not uniform per *** effects of soil conservation in the plots were superior to those of water *** of the RE and SE values presented a positive effect on water and soil *** main factor that caused different effects was rainfall *** heavy rains(e.g.,rainfall erosivity R = 145 MJ mm/ha h and maximum 30 min intensity I30 = 13 mm/h),the main effects were positive,wher

关键词： Water loss Soil erosion Pinus massoniana Soil conservation Transformation LAI

Equality Testing for Soil Grid Unit Resolutions to Polygon Unit Scales with DNDC Modeling of Regional SOC Pools

在线全文

学校读者我要写书评

暂无评论

Chinese Geographical Science 2017年第4期27卷 552-568页

作者： YU Dongsheng PAN Yue ZHANG Haidong WANG Xiyang NI Yunlong ZHANG Liming shi xue-zheng State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China University of Chinese Academy of Sciences Beijing 100393China College of Resource and Environment Fujian Agriculture and Forestry UniversityFuzhou 350002China

Matching soil grid unit resolutions with polygon unit map scales is important to minimize the uncertainty of regional soil organic carbon(SOC) pool simulation due to their strong influences on the modeling.A series of soil grid units at varying cell sizes was derived from soil polygon units at six map scales,namely,1:50 000(C5),1:200 000(D2),1:500 000(P5),1:1 000 000(N1),1:4 000 000(N4) and 1:14 000 000(N14),in the Taihu Region of *** soil unit formats were used for regional SOC pool simulation with a De Nitrification-DeC omposition(DNDC) process-based model,which spans the time period from 1982 to 2000 at the six map *** indices,namely,soil type number(STN),area(AREA),average SOC density(ASOCD) and total SOC stocks(SOCS) of surface paddy soils that were simulated by the DNDC,were distinguished from all these soil polygon and grid *** to the four index values(IV) from the parent polygon units,the variations in an index value(VIV,%) from the grid units were used to assess its dataset accuracy and redundancy,which reflects the uncertainty in the simulation of SOC *** soil grid unit resolutions were generated and suggested for the DNDC simulation of regional SOC pools,matching their respective soil polygon unit map *** these optimal raster resolutions,the soil grid units datasets can have the same accuracy as their parent polygon units datasets without any redundancy,when VIV ship between the optimal soil grid unit resolution(y,km) and soil polygon unit map scale(1:10 000x),the ratio(R?,%) of the optimal soil grid size to average polygon patch size(?,km^2) and the ?,with the highest R^2 among different mathematical regressions,*** knowle

关键词： soil organic carbon(SOC) soil grid unit resolutions soil polygon unit map scales DeNitrification-DeComposition(DNDC) model SOC pools

Variation of Sediment Concentration and Its Drivers Under Different Soil Management Systems

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2010年第5期20卷 578-585页

作者： ZHANG Wen-Tai YU Dong-Sheng shi xue-zheng TAN Man-Zhi LIU Liu-Song State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 (China) College of Geography Sciences Nanjing Normal University Nanjing 210046 (China) Graduate University of the Chinese Academy of Sciences Beijing 100049 (China)

In order to prevent soil erosion in southern China,a study was performed to determine the drivers of sediment concentration variation using simulated rainfall and four soil management systems under field *** soil management systems,i.e.,forest and grass coverage(FG),forest coverage with disturbed soil surface(FD),contour tillage(CT) and downslope tillage(DT),were exposed to two rainfall intensities(40 and 54 mm h-1) using a portable rainfall *** drivers of sediment concentration variation were determined by the variations of runoff rate and sediment concentration as well as their *** effects of the four soil management systems in preventing water and soil losses were compared using runoff rates and sediment concentrations at steady *** runoff initial stage,sediment concentration variation was mainly driven by rainfall and *** degree of sediment concentration variation driven by flow varied with different soil management *** best relationships between runoff rate and sediment concentration were identified,i.e.,reciprocal(CT),quadratic(FG and FD) and exponential(DT).At steady state,runoff rates of the four soil management systems varied slightly,whereas their sediment concentrations varied *** and CT were recommended as the best soil management systems for preventing water and soil losses.

关键词： runoff rate runoff steady state simulated rainfall soil erosion

Spatio-Temporal Variability of Soil Salinity in Alluvial Plain of the Lower Reaches of the Yellow River——A Case Study

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第6期21卷 793-801页

作者： LI Kai-Li CHEN Jie TAN Man-Zhi ZHAO Bing-Zi MI Shu-Xiao shi xue-zheng State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 （China） Graduate University of Chinese Academy of Sciences Beijing 100049 （China） Department of Geography Jiangsu Institute of Education Nanjing 210013 （China） School of Water Conservation and Environment Zhengzhou University Zhengzhou 450000 （China）

Soil salinity and hydrologic datasets were assembled to analyze the spatio-temporal variability of salinization in Fengqiu County, Henan Province, China, in the alluvial plain of the lower reaches of the Yellow River. The saline soil and groundwater depth data of the county in 1981 were obtained to serve as a historical reference. Electrical conductivity （EC） of 293 surface soil samples taken from 2 kin x 2 km grids in 2007 and 4{） soil profiles acquired in 2（108 was analyzed and used for comparative mapping. Ordinary kriging was applied to predict EC at unobserved locations to derive the horizontal and vertical distribution patterns and variation of soil salinity. Groundwater table data from 22 observation wells in 2008 were collected and used as input for regression kriging to predict the maximum groundwater depth of the county in 2008. Changes in the groundwater level of Fengqiu County in 27 years from 1981 to 2008 was calculated. Two quantitative criteria, the mean error or bias （ME） and the mean squared error （MSE）, were computed to assess the estimation accuracy of the kriging predictions. The results demonstrated that the soil salinity in the upper soil layers decreased dramatically and the taxonomically defined saline soils were present only in a few micro-landscapes after 27 years. Presently, the soils with relatively elevated salt content were mainly distributed in depressions along the Yellow River bed. The reduction in surface soil salinity corresponded to the locations with deepened maximum groundwater depth. It could be concluded that groundwater table recession allowed water to move deeper into the soil profile, transporting salts with it, and thus played an important role in reducing soil salinity in this region. Accumulation of salts in the soil profiles at various depths below the surface indicated that secondary soil salinization would occur when the groundwater was not controlled at a safe depth.

关键词： electrical conductivity groundwater table kriging salinization salt content

Environmental Factors Affecting Temporal and Spatial Dynamics of Soil Erosion in Xingguo County, South China

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2005年第5期15卷 620-627页

作者： WANG Ku shi xue-zheng YU Dong-Sheng shi De-Ming CHEN Jing-Ming XU Bin-Bin LIANG Yin LI De-Cheng State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences.Nanjing 210008 （China） Department of Geography University of Toronto Toronto M5S 3G （Canada） Department of Geographic Science Minjiang University Fuzhou 350011 （China）

By using soil erosion maps of four different time periods and a digital elevation model (DEM), in combination withthe remote sensing and GIS technologies, soil erosion dynamics in Xingguo County of Jiangxi Province in South Chinawere analyzed on both temporal and spatial scales in soils of different parent materials, altitudes and slopes. The resultsshowed that from 1958 to 2000 severe soil erosion was coming under control with a decreasing percentage of the land undersevere erosion. It was also found that the soils developed from Quaternary red clay, granite and purple shale were moresusceptible to soil erosion and that areas sitting between 200 to 500 m in altitude with a slope less than 3° or between7° to 20° where human activities were frequent remained to be zones where soil erosion was most likely to occur. Theseareas deserve special attention in monitoring and controlling.

关键词： GIS remote sensing soil erosion South China Xingguo County

National Scale Analysis of Soil Organic Carbon Storage in China Based on Chinese Soil Taxonomy

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2007年第1期17卷 11-18页

作者： YU Dong-Sheng shi xue-zheng WANG Hong-Jie SUN Wei-Xia E. D. WARNER LIU Qing-Hua State Key Laboratory of Soil and Snstainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 China Office for Remote Sensing of Earth Resources Penn State Institutes of the Environment Penn State University PA 16805-4900 （USA）

Patterns of soil organic carbon (SOC) storage and density in various soil types or locations are the foundation for examining the role of soil in the global carbon cycle. An assessment of SOC storage and density patterns in China based on soil types as defined by Chinese Soil Taxonomy (CST) and the recently compiled digital 1:1000000 Soil Database of China was conducted to generate a rigorous database for the future study of SOC storage. First, SOC densities of 7 292 soil profiles were calculated and linked by soil type to polygons of a digital soil map using geographic information system resulting in a 1:1 000 000 SOC density distribution map of China. Further results showed that soils in China covered 9 281×103 km2 with a total SOC storage of 89.14 Gt and a mean SOC density 96.0 t ha-1. Among the 14 CST orders, Cambosols and Argosols constituted high percentage of China's total SOC storage, while Andosols, Vertosols, and Spodsols had a low percentage. As for SOC density, Histosols were the highest, while Primosols were the lowest. Specific patterns of SOC storage of various soil types at the CST suborder, group, and subgroup levels were also described. Results obtained from the study of SOC storage and density of all CST soil types would be not only useful for international comparative research, but also for more accurately estimating and monitoring of changes of SOC storage in China.

关键词： Chinese soil taxonomy soil database soil organic carbon soil type storage

Recent Progress in Fabrication and Structural Design of Thermal Conductive Polymer Composites

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第3期42卷 277-291,I0004页

作者： Yuan-Kai Du zheng-xue shi Shan Dong Hui Jin xue Ke Pei Zhao Bing-Bing Jiang Feng You Hubei Key Laboratory of Plasma Chemistry and Advanced Materials School of Material Science and EngineeringWuhan Institute of TechnologyWuhan 430205China Key Laboratory of Green Preparation and Application of Functional Materials Ministry of EducationHubei UniversityWuhan 430062China Institute of Molecular Aggregation Science Tianjin UniversityTianjin 300072China

In recent years, the demand direction for electronic equipment has expanded into embedded and miniaturized devices. The heat radiation problem has become one of the most significant factors for hindering the development of electronic devices. Since heat radiation material is one of the important components in electronic devices, the demand for enhancing thermal conductivity is also increasingly urgent. Research on thermal conductive polymer composites has become a major direction for developing functional composites. This work reviewed the recent progress in the fabrication of thermal conductive polymer composites. Five different structures are presented, including the using of single fillers,hybrid fillers, double threshold percolation structure, segregated structure and other complex multiphase structures. Specifically, the preparation of high-performance thermal conductive polymer composites was introduced through the combination of various thermal conductive ***, the development direction of high thermal conductive polymer composites was briefly explored.

关键词： Thermal conductive polymer Hybrid fillers Polymer composite Thermal resistance

Effect of Soil Sampling Density on Detected Spatial Variability of Soil Organic Carbon in a Red Soil Region of China

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第2期21卷 207-213页

作者： YU Dong-Sheng ZHANG Zhong-Qi YANG Hao shi xue-zheng TAN Man-Zhi SUN Wei-Xia WANG Hong-Jie College of Geographical Sciences Nanjing Normal University Nanjing 210046 (China) State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008(China) Graduate University of Chinese Academy of Sciences Beijing 100099 (China) Xuzhou Normal Unsiversity Xuzhou 221116 (China)

Spatial variability of soil organic carbon (SOC) of different land use patterns and soil types was examined in a county-wide red soil region of South China,using six sampling densities,14,34,68,130,255,and 525 samples designed by the method of grid sampling in 6 different grid sizes,labeled as D14,D34,D68,D130,D255,and D525,*** results showed that the coefficients of variation (CVs) of SOC decreased gradually from 62.8% to 47.4% with the increase in soil sampling *** SOC CVs in the paddy field change slightly from 30.8% to 28.7%,while those of the dry farmland and forest land decreased remarkably from 58.1% to 48.7% and from 99.3% to 64.4%,*** SOC CVs of the paddy soil change slightly,while those of red soil decreased remarkably from 82.8% to 63.9%.About 604,500,and 353 (P < 0.05) samples would be needed a number of years later if the SOC change was supposedly 1.52 g kg-1,based on the CVs of SOC acquired from the present sampling densities of D14,D68,and D525,***,based on the same SOC change and the present time CVs at D255,the ratio of samples needed for paddy field,dry farmland,and forest land should be 1:0.81:3.33,while the actual corresponding ratio in an equal interval grid sampling was 1:0.74:*** indicated that the sampling density had important effect on the detection of SOC variability in the county-wide region,the equal interval grid sampling was not efficient enough,and the respective CV of each land use or soil type should be fully considered when determining the sampling number in the future.

关键词： coefficient of variation county-wide region grid sampling land use soil type

Modeling Carbon Dynamics in Paddy Soils in Jiangsu Province of China with Soil Databases Differing in Spatial Resolution

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2011年第6期21卷 696-705页

作者： XU Sheng-Xiang shi xue-zheng ZHAO Yong-Cun YU Dong-Sheng WANG shi-Hang ZHANG Li-Ming C. S. LI TAN Man-Zhi State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 （China） Graduate University of Chinese Academy of Sciences Beijing 100049 （China） College of Environmental and Resource Sciences Fujian Agriculture and Forestry University Fujian 350002 （China） Institute for the Study of Earth Oceans and Space Complex Systems Research Center University of New Hampshire Durham NH03824 （USA）

A number of process-based models have been developed for quantifying carbon(C)sequestration in *** DeNitrification-DeComposition(DNDC)model was used to simulate and quantify long-term(1980-2008)soil organic carbon(SOC)dynamics in the important rice-producing province,Jiangsu,*** in SOC storages were estimated from two soil databases differing in spatial resolution:a county database consisting of 68 polygons and a soil patch-based database of 701 polygons for all 3.7 Mha of rice fields in *** simulated SOC storage with the coarse resolution county database ranged between 131.0-320.6 Tg C in 1980 and 170.3-305.1 Tg C in 2008,respectively,while that estimated with the fine resolution database was 201.6 and 216.2 Tg C in 1980 and 2008,*** results modeled with the soil databases differing in spatial resolution indicated that using the soil input data with higher resolution substantially increased the accuracy of the modeled results;and when lacking detailed soil datasets,the DNDC model,parameterized with the most sensitive factor(MSF) method to cope with attribute uncertainty,could still produce acceptable results although with deviations of up to 60% for the case study reported in this paper.

关键词： 1:1 000000 soil map C sequestration rate DeNitrification-DeComposition (DNDC) greenhouse gas soil organic carbon (SOC)