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| 1 | Spatiotemporal variations of vegetation cover on the Chinese Loess Plateau(1981―2006):Impacts of climate changes and human activities显示文摘Spatiotemporal variations of Chinese Loess Plateau vegetation cover during 1981-2006 have been investigated using GIMMS and SPOT VGT NDVI data and the cause of vegetation cover changes has been analyzed, considering the climate changes and human activities. Vegetation cover changes on the Loess Plateau have experienced four stages as follows: (1) vegetation cover showed a continued increasing phase during 1981―1989; (2) vegetation cover changes came into a relative steady phase with small fluctuations during 1990―1998; (3) vegetation cover declined rapidly during 1999―2001; and (4) vegetation cover increased rapidly during 2002―2006. The vegetation cover changes of the Loess Plateau show a notable spatial difference. The vegetation cover has obviously increased in the Inner Mongolia and Ningxia plain along the Yellow River and the ecological rehabilitated region of Ordos Plateau, however the vegetation cover evidently decreased in the hilly and gully areas of Loess Plateau, Liupan Mountains region and the northern hillside of Qinling Mountains. The response of NDVI to climate changes varied with different vegetation types. NDVI of sandy land vegetation, grassland and cultivated land show a significant increasing trend, but forest shows a decreasing trend. The results obtained in this study show that the spatiotemporal variations of vegetation cover are the outcome of climate changes and human activities. Temperature is a control factor of the seasonal change of vegetation growth. The increased temperature makes soil drier and unfavors vegetation growth in summer, but it favors vegetation growth in spring and autumn because of a longer growing period. There is a significant correlation between vegetation cover and precipitation and thus, the change in precipitation is an important factor for vegetation variation. The improved agricultural production has resulted in an increase of NDVI in the farmland, and the implementation of large-scale vegetation construction has led to some beneficial effect in ecology. | XIN ZhongBao1,2, XU JiongXin1 & ZHENG Wei1, 2 1 Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 2 Graduate University of the Chinese Academy of Sciences, Beijing 100049, China | 2008 | Science China Earth Sciences2008，51，1： | 112 |
| 2 | Paleoclimatic significance of grain size of loess-palaeosol deposit in Chinese Loess Plateau显示文摘Particle size analysis for samples from three last glacial cycle loess_palaeosol profiles along a northwest_southeast transection on the Chinese Loess Plateau has been carried out. The paleoclimatic significance of grain size indices has been obtained by analyzing the fraction content variations and their comparisons with global ice volume and solar radiation variations. The results show that (i) paleoclimatic significance of the grain size indices of loess_palaeosol deposit is different with grain size fraction content and sampling points in Chinese Loess Plateau; (ii) the sub_coarse grain fraction is a good proxy index of East Asia winter monsoon strength and therefore can be used to detect the global climate changes; (iii) the content of sub_fine and fine grain fractions is influenced by both the input of sub_coarse grain fraction and pedogenesis; (iv) the sub_coarse fraction exhibits a negative relationship with the sub_fine and fine fraction. | 鹿化煜 安芷生 | 1998 | Science China Earth Sciences1998，41，6： | 47 |
| 3 | Eolian evidence from the Chinese Loess Plateau: the onset of the Late Cenozoic Great Glaciation in the Northern Hemisphere and Qinghai-Xizang Plateau uplift forcing显示文摘On the basis of a newly-constructed record of magnetic susceptibility (SUS) and the depositional rate change of eolian loess-red clay sequences in the last 7.2 Ma BP from the Loess Plateau, together with a comparison of a record of δ18O values from the equatorial East Pacific Ocean and eolian Quartz flux variations from the North Pacific Ocean, the evolutionary process of the Late Cenozoic Great Glaciation in the Northern Hemisphere can be divided into three stages: the arrival stage around 7.2—3.4 Ma BP, the initial stage at about 3.4—2.6 Ma BP, and the Great Ice Age since 2.6 Ma BP. The evolution of the East Asian monsoon is characterized by paired winter and summer monsoons, and it is basically composed of the initial stage of weak winter and summer monsoons, the transitional stage of simuhaneous increase in intensity of winter and summer monsoons, and the prevailing stage of strong winter and weak summer monsoons, or weak winter and strong summer monsoons. The Late Cenozoic global tectonic | 安芷生 王苏民 吴锡浩 陈明扬 孙东怀 刘秀铭 王富葆 李力 孙有斌 周卫健 周杰 刘晓东 鹿化煜 张云翔 董光荣 强小科 | 1999 | Science China Earth Sciences1999，42，3： | 39 |
| 4 | Loess in the Tian Shan and its implications for the development of the Gurbantunggut Desert and drying of northern Xinjiang显示文摘Eolian loess is widely distributed on the various geomorphic surfaces between 700-2400 m a.s.l. on the northern slope of the Tian Shan. It is formed in a synchronous manner with dust transported from the Gurbantunggut Desert in the Junggar Basin. The thickest section of loess was found in the Shawan and Shihezi regions. Paleomagnetic and climatic proxy analyses of over 71 m of a loess-paleosol sequence on the highest terrace of the Qingshui He (River) in the Shawan show that the paleomagnetic Bruhues/Matuy-ama (B/M) boundary lies at the bottom of paleosol S8, at a depth of 69.5 m, and the bottom of the sequence was estimated to be -0.8 Ma. This implies that the extremely dry climatic conditions in the Junggar Basin and the initial Gurbantunggut Desert were present at least by 0.8 Ma. High-resolution grain size series demonstrate that this area and desert expansion experienced two dramatic periods of desert expansions that occurred at -0.65 Ma and 0.5 Ma, respectively; and the subsequent continuous | FANG Xiaomin SHI Zhentao YANG Shengli YAN Maodu LI Jijun JIANG Ping’an | 2002 | Chinese Science Bulletin2002，47，16： | 33 |
| 5 | The effect of land use structure on the distribution of soil nutrients in the hilly area of the Loess Plateau,China显示文摘The irrational land use is one of the main reasons for the soil erosion and nutrient loss in the loess hilly area of China. In this project, 4 types of typical land use structure of sustain ment for about 15 years in the loess hill slope are selected to study the effect of land use structure on the distribution of soil nutrients. From hill bottom to hill top, the patterns of land use types are:, grassland-slope farmland-forest, slope farmland-grassland-forest, terrace-grassland-forest and slope farmland-forest-grassland. By measuring the contents of the total N, total P, available N, available P and organic matter of soils, the results show that the land use structure types of slope farmland-grassland-forest and terrace-grassland-forest have a better capacity to maintain the soil nutrients. | Bojie Fu Keming Ma Huafeng Zhou Liding Chen | 1999 | Chinese Science Bulletin1999，44，8： | 32 |
| 6 | Soil water depletion depth by planted vegetation on the Loess Plateau显示文摘Evapotranspiration of much planted vegetation exceeds precipitation, and this can deplete soil water and cause a deep dry layer in the soil profile, which is a serious obstacle to sustainable land use on the Loess Plateau, China. This study aimed to determine water depletion depth of planted grassland, shrub, and forest in a semiarid area on the Loess Plateau. Soil moisture of five vegetation types was measured to >20 m in depth. The vegetation types were crop, natural grasse, seven-year-old planted alfalfa (Medicago sativa L.), 23-year-old planted caragana (Caragana microphylla Lam.) shrub, and 23-year-old planted pine (Pinus tabulaeformis L) forest land. Through comparing moisture of planted alfalfa grass, caragana shrub, and pine forest to crop and natural grassland, the depth and amount of soil water consumed by grassland, caragana brush and pine forest was determined. The depth of soil water depleted by alfalfa, caragana brush, and pine forest reached 15.5, 22.4 and 21.5 m, respectively. | WANG ZhiQiang LIU BaoYuan LIU Gang ZHANG YongXuan | 2009 | Science China Earth Sciences2009，52，6： | 29 |
| 7 | The carbon isotope composition of C3 herbaceous plants in loess area of northern China显示文摘d 13C of 367 C3 herbaceous plants was measured in loess area in northern China. Their d 13C values vary between -21.7 and -30.0, with a mean of -26.7. In the center of Loess Plateau (semimoist area) with annual precipitation of 400─600 mm, the d 13C values of C3 herba-ceous plants range from -24.4 to -28.5, with a mean of -27.5. In the west of Loess Plateau (semiarid and arid area) with annual precipitation less than 400 mm, they range between -21.7 and -30.0, with a mean of -26.2. Annual precipitation is the main factor that makes d 13C val-ues of C3 herbaceous plants in the west greater than those in the central Loess Plateau. The composition of d 13C in C3 plants increases with deceasing annual precipitation, and the mean change is -0.49/100 mm. | 王国安 韩家懋 刘东生 | 2003 | Science China Earth Sciences2003，46，10： | 26 |
| 8 | Two pedogenic models for paleoclimatic records of magnetic susceptibility from Chinese and Siberian loess显示文摘The magnetic susceptibility (MS) of Chinese loess showing a general proportional relationship to pedogenic grade has been widely recognized and used for reconstruction of paleoclimate by Quaternary scientists. The in-situ pedogenic enhancement of ferrimagnetic content is normally believed to be the main reason for the increase of susceptibility in soil units. However, this pattern of high magnetic susceptibility in palaeosols, and low values in loess, are not replicated in some loess deposits. Siberian loess deposits display a completely opposite susceptibility behavior: high values in loess and low values in palaeosols. This inverse relationship has been explained by the idea that magnetic susceptibility is reflecting the magnitude of an aeolian ferrimagnetic component of consistent mineralogy, the grain size of which is related to average wind velocity. Our magnetic study of Siberian samples in this paper suggests that there are notable differences in magnetic properties between Siberian loess and developed palaeosols, not only in magnetic grain-size and concentration but also in magnetic mineralogy. This evidence is difficult to explain fully through variation in wind strength alone, but implies that the low magnetic susceptibility values in the Siberian paleosol units are a reflection, at least in part, of the alteration of the ferrimagnetic content by post-depositional processes. The Loess Plateau is a very arid area where potential evaporation is always higher than precipitation; pedogenesis occurs under dry oxidising conditions. The Siberian Kurtak region is located on the edge of the tundra where it is always wet and saturation during interglacials will lead to a reducing pedogenic environment. Ferrimagnetic minerals under this condition will be destroyed, resulting in lower magnetic susceptibility. Therefore, great care should be taken when using susceptibility values for paleoclimatic reconstruction. | Paul HESSE Jiri CHLACHULA | 2008 | Science China Earth Sciences2008，51，2： | 25 |
| 9 | Carbon isotopic composition of modern soil and paleosol as a response to vegetation change on the Chinese Loess Plateau显示文摘The relationship between the carbon isotopic composition of paleosols and paleovegetation on the Loess Plateau is still unclear. One of the main reasons is that we are short of knowledge about the characteristics of the carbon isotopic composition of modern soil in this area. A preliminary investigation of the carbon isotopic compositions of the modern soil and the loess/paleosol sequence on the Loess Plateau shows that the carbon isotopic composition of modern soil is consistent with the distribution of modern plants on the Loess Plateau, where the ecosystem is dominated by a mixture of C4 and C3 plants. Comparing theδ13C values of modern soil and loess-paleosol sequences from the Xunyi profile, we conclude that C3 plants dominated the landscape during loess sediment stages, while C4 plants expanded during paleosol stages. | LIU Weiguo NING Youfeng AN Zhisheng WU Zhenghai LU Huayu CAO Yunning | 2005 | Science China Earth Sciences2005，48，1： | 24 |
| 10 | A sedimentological proxy indicator linking changes in loess and deserts in the Quaternary显示文摘From Yulin, which is located in the transitional zone between the Loess Plateau and the Mu Us desert, to Weinan in the southernmost part of the Loess Plateau, 9 loess sections were studied. Grain size analyses show that the advance-retreat changes of the deserts in northern China may be the most important factor controlling changes in the sand particle percentage of the loess-soil sequences during the last glacial-interglacial period. It is thus suggested to use the sand grain content of loess deposits as a proxy indicator of desert variations. Applying this indicator to the last glacial loess deposits in the northwestern part of the Loess Plateau reveals that there were many millennial-scale cycles of the desert environments. | 丁仲礼 孙继敏 刘东生 | 1999 | Science China Earth Sciences1999，42，2： | 24 |
| 11 | The incorporation of thermal methods in mineral magnetism of loess-paleosol sequences: a brief overview显示文摘The advantages of thermal methods for mineral-magnetic research of loess/paleosolsequences are illustrated in an introductory overview. When applying thermal methods, magnetiteand maghemite can be distinguished, something which is difficult with field-dependentmeasurements at room temperature. Also, variable low-temperature oxidation that is related toclimate may be quantified. Thirdly, grain-size estimates pertaining to the whole superparamagneticrange can be inferred from LT warming experiments and to a lesser extent from variable chemicalalteration during heating. Application of mineral-magnetic techniques may lead to thedevelopment of quantifiable proxy parameters for paleoclimate. | A.J.VanVelzen M.J.Dekkers | 1999 | Chinese Science Bulletin1999，44，S1： | 24 |
| 12 | History of the temperature-dependence of susceptibility and its implications: Preliminary results along an E-W transect of the Chinese Loess Plateau显示文摘An investigation of rock magnetic properties using the temperature-dependence ofsusceptibility (TDS) and the coercivity of different IRM components was conducted on samples ofthe Malan loess (L1) and the last interglacial soil (S1) along an E-W transect of the Chinese LoessPlateau. We find that the behavior of the TDS is useful in identifying maghemite (γ-Fe2O3) in bothloess and paleosol, and that it can be used as a new proxy of the degree of pedogenesis, which isclosely linked to climatic conditions. Based on results from the TDS, we conclude that (1) thedetrital magnetite grains predominate in the L1 unit to the west of Liupan Mts, where theweathering and pedogenetic processes were weakest; (2) a comparable degree of pedogenesisexists in the L1 at the east of the Liupan Mts and the S1 at the west of the Liupan Mts; (3) a higherconcentration of maghemite is found in the S1 unit at the eastern sections, suggesting that the localclimate was warmer and more humid in this interval. In addition, we propose that TDSmeasurements can be used as a rapid means of determining the reliability of the paleomagneticsecular variation (PSV) record in loess/poleoso/sequenees. | ZHU Rixiang LIN Mian PAN Yongxin 1) Institute of Geophysics. Chinese Academy of Sciences. Beijing 100101 2) Institute of Mechanism. Chinese Academy of Sciences, Beijing 100080 | 1999 | Chinese Science Bulletin1999，44，S1： | 24 |
| 13 | History and variability of Asian interior aridity recorded by eolian flux in the Chinese Loess Plateau during the past 7 Ma显示文摘Eolian flux in the Chinese Loess Plateau was reconstructed by measuring the dry bulk density and CaCO3 content of the late Cenozoic loess-paleosol-red clay sequences in the Lingtai profile. Comparison of eolian flux variation between the Lingtai profile and the ODP sites 885/886 in the North Pacific shows a significant wet-dry variability in addition to a gradual drying trend in the dust source regions in interior Asia. Especially, the increase of eolian fluxes from both continental and pelagic eolian sediments indicates a sharp drying of the dust source regions between 3.6 and 2.6 MaBP, which might be attributed to the tectonic uplift of the Tibetan Plateau, which cut down the moisture input to the interior Asia. The average value and variability of eolian flux are higher after 2.6 MaBP than before, which may be related to the Quaternary climatic fluctuations on the glacial-interglacial timescale after the commencement of major Northern Hemisphere Glaciations. The eolian fluxes of the Lingtai profile and Core V21-146 in northwest Pacific show a synchronous variation on the 104-105 a timescale, indicating that the flux variations from both continental and marine records are closely correlated to the Quaternary climatic fluctuation forced by the ice volume changes on a global scale. | 孙有斌 安芷生 | 2002 | Science China Earth Sciences2002，45，5： | 23 |
| 14 | Geochemical studies on the intensity of chemical weathering in Luochuan loess-paleosol sequence, China显示文摘Major and trace element analyses of the Luochuan loess paleosol sequence in China were performed in order to understand the chemical weathering processes occurring on the Loess Plateau during the last 600 ka. Results reveal that most elements in the loess remain immobile during chemical weathering. The typical stable elements are Al, K, Ti, Rb and REE, while the main mobile elements are Ca, Sr, P, Mg and Na. Loess and paleosol experience the incipient stage of chemical weathering characterized by acid leaching and carbonate dissolution. Alteration of silicates in the sequence seems to be limited. Features of less chemical weathering of the loess and paleosol could be indicators for the dry cold climate dominated on the Loess Plateau during the Quaternary. | 陈骏 季峻峰 仇纲 鹿化煜 | 1998 | Science China Earth Sciences1998，41，3： | 22 |
| 15 | Research on the slope spectrum of the Loess Plateau显示文摘A new concept dealing with digital analysis of loess terrain,slope spectrum,is presented and discussed in this paper,by introducing its characteristic,represen-tation and extracting method from DEMs. Using 48 geomorphological units in dif-ferent parts of the loess as test areas and 5 m-resolution DEMs as original test data,the quantitative depiction and spatial distribution of slope spectrum in China's Loess Plateau have been studied on the basis of a series of carefully-designed experiments. In addition,initial experiment indicates a strong relationship between the slope spectrum and the loess landform types,displaying a potential importance of the slope spectrum in geomorphological studies. Based on the slope spectrums derived from the 25 m-resolution DEM data in whole loess terrain in northern part of Shaanxi,13 slope spectrum indices were extracted and integrated into a compre-hensive layer with image integration method. Based on that,a series of unsuper-vised classifications was applied in order to make a landform classification in northern Shaanxi Loess Plateau. Experimental results show that the slope spec-trum analysis is an effective method in revealing the macro landform features. A continuous change of slope spectrum from south to north in northern Shaanxi Loess Plateau shows an obvious spatial distribution of different loess landforms. This also proves the great significance of the slope spectrum method in describing the terrain roughness and landform evolution as well as a further understanding on landform genesis and spatial distribution rule of different landforms in the Loess Plateau. | TANG GuoAn,LI FaYuan,LIU XueJun,LONG Yi & YANG Xin Key Laboratory of Virtual Geographic Environment,Nanjing Normal University,Ministry of Education,Nanjing 210046,China | 2008 | Science China(Technological Sciences)2008，51，S1： | 22 |
| 16 | Loess magnetic properties in the Ili Basin and their correlation with the Chinese Loess Plateau显示文摘Over the past two decades, magnetoclimatological studies of loess-paleosol sequences in the Chinese Loess Plateau (CLP) have made outstanding achievements, which greatly promote the understanding of East Asian paleomonsoon evolution, inland aridification of Asia, and past global climate changes. Loess magnetic properties of the CLP have been well studied. In contrast, loess magnetic properties from outside the CLP in China have not been fully understood. We have little knowledge about the magnetic properties of loess in the Ili Basin, an intermontane depression of the Tianshan (or Tien Shan) Mountains. Here, we present the results of rock magnetic measurements of the Ili loess including mass magnetic susceptibility (χ) and anhysteretic remanent magnetization (ARM), high/low temperature dependence of susceptibility (TDS) and hysteresis, as well as X-ray diffraction (XRD) for mineral analysis. Based on the comparison with loess-paleosol sequences in the CLP (hereafter referred to as the Chinese loess), we discuss the possible magnetic susceptibility enhancement mechanism of the Ili loess. The results show that 1) the total magnetic mineral concentration of the Ili loess is far lower than that of the Chinese loess, though they have similar magnetic mineral compositions. The ferrimagnetic minerals in the Ili loess are magnetite and maghemite, and the antiferromagnetic mineral is hematite; XRD analysis also identifies the presence of ilmenite. The ratio of maghemite is lower in the Ili loess than in the Chinese loess, but the ratios of magnetite and hematite are higher in the Ili loess than in the Chinese loess. 2) The granularity of magnetic minerals in the Ili loess, dominated by pseudo-single domain (PSD) and multi-domain (MD) grains, is generally much coarser than that of the Chinese loess. Ultrafine pedogenically-produced magnetic grains have a very limited contribution to the susceptibility enhancement. Rather, PSD and MD particles of magnetite and maghemite are the main contributors to the enhancement of susceptibility in the Ili loess. 3) The susceptibility enhancement mechanism for the Ili loess is complicated and superimposes both a wind velocity/vigor model (Alaskan or Siberian model) and the in situ ultrafine grain pedogenic model; the former might play an important role in the Ili loess. 4) Magnetic susceptibility enhancements of the Ili loess are related not only to the eolian input of the source area, but also to the local climate, landform, and geological background. Therefore, great care should be taken when reconstructing paleoclimate using magnetic susceptibility data from the Ili loess. | NAOTO Ishikawa | 2010 | Science China Earth Sciences2010，53，3： | 21 |
| 17 | Pretreated methods on loess-palaeosol samples granulometry显示文摘Twenty representative samples were collected from the Chinese loess plateau and each sample was prepared in 6 different ways respectively in order to test the influences of pretreated methods on grain size measurement. The results show that (ⅰ) different pretreated methods can make a big difference for the samples granulometry; (ⅱ) soaking in distilled water for one day, and then treating with an ultrasonic machine for 10 min can make the sample dispersed. | Huayu Lu Zhisheng An | 1998 | Chinese Science Bulletin1998，43，3： | 20 |
| 18 | Distribution of Rb and Sr in the Luochuan loess-paleosol sequence of China during the last 800 ka——Implications for paleomonsoon variations显示文摘The concentrations of Rb and Sr, and magnetic susceptibility in loess and paleosol samples from the Luochuan profile have been measured. The loess units deposited in different geological periods display a very similar pattern of Rb and Sr distribution while paleosol units exhibit a dramatic increase in the Rb/Sr ratio, ranging from 20% to 120% in increase amplitude. Owing to different geochemical behavior of the two elements, Rb appears to be immobile while Sr appears to be mobile in the processes of weathering and pedogenesis. So variations of the Rb/Sr ratio in the loess-paleosol sequences could reflect intensities of weathering and pedogenesis, thus recording the relative wind strength of the East Asian summer monsoon circulation. This could be supported by the high degree of correlation between the Rb/Sr ratio and the magnetic susceptibility. A continuous record of the Rb/Sr ratio in the Luochuan profile over the last 800 ka bears a striking resemblance to the δ18O curve of the deep sea | 陈骏 安芷生 汪永进 季峻峰 陈旸 鹿化煜 | 1999 | Science China Earth Sciences1999，42，3： | 19 |
| 19 | Micromorphology of the loess-paleosol sequence of the last 130 ka in China and paleoclimatic events显示文摘The Late Quaternary loess-soil sequences in Xifeng, Luochuan and Weinan are studied to investigate the micromorphology of both loess and paleosols. Many features have clear climatic implications and may be used as indications for morpho-stratigraphic and climatic correlation. The temporal and spatial variations of these features allow us to define 16 climatic events for the last 130 ka, which are highly consistent with the variations in palco-weathering intensity. Part of these events are attributable to the orbital forcing while others are more or less synchronous with the Heinrich events recorded in the North Atlantic Ocean. During the last events, the Loess Plateau was characterized by sparse vegetation cover and strong winds while the climatic conditions between these events were considerably humid, resulting in a significant steppe cover. | 郭正堂 N.Fedoroff 刘东生 | 1996 | Science China Earth Sciences1996，39，5： | 18 |
| 20 | Carbon isotope ratios of C_(4) plants in loess areas of North China显示文摘Carbon isotope ratios (δ 13C) of 89 C4 plant samples were determined from the loess area in North China. δ 13C values vary between –10.5‰ and –14.6‰ with a mean of –12.6‰. Along a pre-cipitation gradient from the semi-moist area to the semiarid area, then to the arid area, the δ 13C val-ues of C4 plants show a slight decreasing trend. The δ 13C values of C4 plants in the dry season are found lower than those in the wet season. These trends are opposite to those observed for C3 spe-cies. | WANG Guoan1,2,3, HAN Jiamao 2, ZHOU Liping3, XIONG Xiaogang4, TAN Ming2, WU Zhenhai5 & PENG Jun6 1. Department of Plant Nutrition, China Agricultural University, Beijing 100094, China 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China 3. College of Environmental Sciences, MOE Laboratory for Earth Surface Processes, Peking University, Beijing 100871, China 4. Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China 5. Northwest Sci-Tech University of Agriculture and Forestry, Yangling 712100, China 6. Network Center, China Agricultural University, Beijing 100094, China | 2006 | Science China Earth Sciences2006，49，1： | 16 |
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