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    20 November 2011, Volume 66 Issue 11 Previous Issue    Next Issue
    Climatic Suitability of Potential Summer Maize Planting Zones in China
    HE Qijin, ZHOU Guangsheng
    2011, 66 (11):  1443-1450.  doi: 10.11821/xb201111001
    Abstract ( 594 )   PDF (688KB) ( 888 )   Save
    Based on the data from 188 agricultural meteorological observation stations of summer maize and 10 km×10 km spatial resolution climate data in China from 1971 to 2000, the potential climate indices at national and annual scales influencing the distribution of maize planting zones from the references, together with the maximum entropy (MaxEnt) model as well as ArcGIS spatial analysis technique, the relationship between potential summer maize planting zones and climate factors was established, and the potential summer maize planting distribution and its climatic suitability in China were analyzed in this paper. The results show that the key factors affecting summer maize planting distribution include frost-free period, mean annual temperature, ≥ 10 oC accumulated temperature continuous days, ≥ 0 oC accumulated temperature, ≥ 10 oC accumulated temperature, the coldest month average temperature, the warmest month average temperature and annual precipitation. The climatic suitability of potential summer maize planting zones in China could be divided into four levels: optimum area, suitable area, less suitable area and unsuitable area, based on its existence probability from MaxEnt model. Furthermore, the climatic characteristics of different climatic suitability zones of potential summer maize planting are discussed. This research would provide the reference for reasonable use of climatic resources, scientific planning of summer maize planting and policy making to cope with the climate change.
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    Temperature Variation in Recent 50 Years in the Three-River Headwaters Region of Qinghai Province
    YI Xiangsheng, YIN Yanyu, LI Guosheng, PENG Jingtao
    2011, 66 (11):  1451-1465.  doi: 10.11821/xb201111002
    Abstract ( 820 )   PDF (1435KB) ( 759 )   Save
    Based on the monthly average temperature data of 12 meteorological stations in the Three-River Headwaters Region of Qinghai Province from 1961 to 2010, the regional differences and abrupt changes of temperature variation were analyzed by the methods of moving average, linear trend analysis, spline interpolation, and Mann-Kendall test. Some important results were obtained in four aspects as follows. (1) The annual and seasonal average temperature in the Three-River Headwaters Region of Qinghai Province and its source regions was featured by several cold and warm fluctuations, but the average temperature had a significant rising trend at statistical significance level, especially since 2001. Spring, summer, autumn and annual average temperatures tended to be warm significantly since the 1990s and the winter average temperature exhibited a significant increasing trend since 2001. (2) The annual average temperature change tendency rate of the Three-River Headwaters Region of Qinghai Province was 0.36 oC 10a-1, while the annual average temperature change tendency rates of the Yellow River source region, the Lancangjiang River source region and the Yangtze River source region were 0.37 oC 10a-1, 0.37 oC 10a-1 and 0.34 oC 10a-1, respectively. The significant temperature increasing regions were observed in the south of Yushu County and the north of Nangqian County, and the temperature rising trends of winter and autumn were higher than those of spring and summer. (3) The annual, summer, autumn and winter average temperatures in the Three-River Headwaters Region, Lancangjiang River source region and Yangtze River source region as well as the summer and autumn average temperatures in the Yellow River source region had abrupt changes. The annual and summer average temperature abrupt changes were mainly observed in the late 1990s, while the autumn and winter average temperature abrupt changes mainly occurred in the early 1990s and early 21st century respectively. (4) In the background of global climate warming, altitude and underlying surface in different parts of the Qinghai-Tibet Plateau were the reasons for high temperature increasing rate in the Three-River Headwaters Region of Qinghai Province.
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    Spatial Distribution of Atmospheric Water Vapor and Its Relationship with Precipitation in Summer over the Tibetan Plateau
    ZHOU Shunwu, WU Ping, WANG Chuanhui, HAN Juncai
    2011, 66 (11):  1466-1478.  doi: 10.11821/xb201111003
    Abstract ( 680 )   PDF (1007KB) ( 709 )   Save
    By using the observed temperature and humidity dataset of the 14 radiosonde stations and monthly mean precipitation data of 83 ground stations from 1979 to 2008 over the Tibetan Plateau (TP), the relationship between the atmospheric water vapor (WV) and precipitation in summer as well as the precipitation conversion efficiency (PEC) over the TP is analyzed. The statistic results are obtained as follows. (1) The summer WV decreases with increasing altitude, with the largest value area observed in the northeastern part of the TP and the second largest value area in the southeastern part of the TP, while the northwestern part is the lowest value area. The summer precipitation decreases from southeast to northwest. (2) The summer WV presents two main patterns based on the EOF analysis: the whole region consistent-type and the north-south opposite-type. The north-south opposite-type of the summer WV is similar to the first EOF mode of the summer precipitation and both of their zero lines are located to the north of Tanggula Mountains. (3) The summer precipitation is more (less) in the southern (northern) TP in the years with the distribution of north lack of the summer WV while south abundant, and vice versa. (4) The PEC over the TP is between 3% and 38% and it has significant spatial difference in summer, which is obviously bigger in the southern TP than that in the northern TP.
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    Variations of Extreme Cold Winter Events in Southern China in the Past 400 Years
    HAO Zhixin, ZHENG Jingyun, GE Quansheng, DING Lingling
    2011, 66 (11):  1479-1485.  doi: 10.11821/xb201111004
    Abstract ( 703 )   PDF (769KB) ( 946 )   Save
    The extreme cold winter events were defined as the ones with the occurrence probabilities lower than the tenth percentile of the probability density function, based on the observed temperature of winter and January in southern China since 1951. The impacts (including freezing of rivers/lakes, widespread snow/ice storms, and cold damages to subtropical/tropical crops) of these extreme cold winter events occurred since 1951, which were adopted to reconstruct the chronology of extreme cold winter events derived from Chinese documents in southern China during 1600-1950. The most frequent occurrences of extreme cold winter events were observed during 1650-1699, 1800-1849 and 1850-1899, with frequencies twice as many as that in 1950-1999. The frequencies of extreme cold winter events in 1600-1649 and 1900-1949 were a little higher than those in 1950-1999. In contrast, the frequencies of extreme cold winters during 1700-1749 and 1750-1799 were close to those in 1951-1999. Moreover, the occurrence of extreme cold winter events happened year by year or every other year in most of cases. Meanwhile, the intensities of some historical cold events exceeded those of the coldest winter events since 1951.
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    Pattern of Impervious Surface Change and Its Effect on Water Environment in the Beijing-Tianjin-Tangshan Metropolitan Area
    KUANG Wenhui, LIU Jiyuan, LU Dengsheng
    2011, 66 (11):  1486-1496.  doi: 10.11821/xb201111005
    Abstract ( 809 )   PDF (1771KB) ( 909 )   Save
    The impervious surface area (ISA) at the regional scale is one of important environmental factors for examining the interaction and mechanism of Land Use/Cover Change (LUCC) - ecosystem processes - regional climate change under the interactions of urbanization and global environment change. The timely and accurate extraction of ISA from remotely sensed data at the regional scale is becoming a bottle-neck issue. This study improved the MODIS NDVI and DMSP-OLS based ISA extraction method by incorporating LULC information of China. ISA datasets in Beijing-Tianjin-Tangshan Metropolitan Area (BTTMA) in 2000 and 2008 at a spatial resolution of 250 m were developed, their spatial-temporal changes were analyzed, and their impacts on water quality were evaluated. The results indicated that ISA in BTTMA has rapidly increased along urban fringe and urban transportation corridors and coastal belt both in intensity and extents from 2000 to 2008. The growth rates of ISA in Tianjin and three cities (Tanshan, Langfang, and Qinhuangdao) in Hebei Province were greater than that in Beijing. The ISA increase has great impacts on water quality; particularly, the water pollution in the Haihe River has deteriorated due to the increase and intensification of impervious surface areas.
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    Evaluation of Ecological Sensitivity in Karamay, Xinjiang, Northwest China
    PAN Feng, TIAN Changyan, SHAO Feng, ZHOU Wei, CHEN Fei
    2011, 66 (11):  1497-1507.  doi: 10.11821/xb201111006
    Abstract ( 1086 )   PDF (959KB) ( 1080 )   Save
    Based on spatial analysis, and GIS grid computing and overlay techniques, whilst considering the effect of oil-field development and aimed at the ecological problems of Karamay in Xinjiang, we conducted research on the spatial characteristics of the comprehensive ecological sensitivity of Karamay. The ecological problems of natural environment evolution include soil erosion, land desertification, soil salinization, biodiversity reduction. The results of the research are as follows. (1) Soil erosion is relatively sensitive, especially in Karamay District, Dushanzi District, north of Urho District and west of Baijiantan District. (2) The main types of land desertification are represented by high and moderate grade sensitivities, and high and extremely high sensitive areas are distributed in the intersection of Karamay and Baijiantan districts. (3) The soil salinization sensitivity grades are mainly moderate, high and extremely high. The highly sensitive areas are mainly southeast of Baijiantan District, north and east of Karamay District and east of Urho District. The primary causes are evaporation exceeding rainfall and excessive human activities. (4) The main types of biodiversity sensitivity are light and moderate grades. Highly sensitive areas are located in the east and south of Karamay District, north of the Baiyang River Basin and in parts of the wetland areas. (5) Oil development fields are highly ecologically sensitive areas, which are located in the northern oilfields of Urho District, western oilfields of Baijiantan District, northwestern oilfields of Karamay District and central oilfields of the Dushanzi District. (6) The main types of integrated ecological sensitivity are high and moderate. The high and extremely highly sensitive areas are located in the centre and north of Karamay District, and southwest of Baijiantan District.
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    The Analysis of Entropy Changes on the Evolutional Tendency of Geographical Environment
    WANG Yuming
    2011, 66 (11):  1508-1517.  doi: 10.11821/xb201111007
    Abstract ( 809 )   PDF (512KB) ( 810 )   Save
    The evolution of geographical environmental system obeys the second law of thermodynamics: the order degree changes of the system are anti-related to its total entropy changes. The order degree increases when the total entropy changes are negative, and it is useful for human beings' survival and development, and vice versa. The analysis shows that the spontaneous evolution of natural geographical environment is developing towards ordering. The impacts of large-scale human activities on city system and human geographical environment are totally positive, and push its ordering development; their impacts on natural geographical development are both positive and negative. The positive impact is mainly the incremental production of low-entropy material and energy, which has been reflected in the increase of agricultural products and the application of new energy technology, such as solar energy, and ecological environment construction. The negative impacts are consumption of low-entropy material and energy, discharge of "three wastes" and elimination heat to the environment during the process of consumption and industrial production. These impacts lead to decrease of stock of low-entropy material and expansion of entropy increase during the geographical development, and have already caused common anxiety. Ordering of background evolution of natural geographical environment and technological possibility indicate that the evolution of geographical environment can continue ordering by introducing more low-entropy material and energy and decreasing the discharge of entropy.
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    Complex System Theory and Agent-based Modeling: Progresses in Land Change Science
    YU Qiangyi, WU Wenbin, TANG Huajun, YANG Peng, CHEN Zhongxin, CHEN Youqi
    2011, 66 (11):  1518-1530.  doi: 10.11821/xb201111008
    Abstract ( 699 )   PDF (1151KB) ( 927 )   Save
    Based on complex system theory and agent-based models (ABMs), the paper summarizes recent progresses in land change science from the perspective of theory and methodology respectively. Complex system theory is the theoretical basis for carrying out researches on the complex land change issues in the "coupled human and natural systems"; while ABMs, one of the key tools for complex system studies, introduces innovating perspective to traditional land change modeling. The integration of ABMs and land use/cover change models (ABM/LUCC) has achieved several important breakthroughs recently; however, some of the crucial issues remain unsolved, such as the problem of "theory divorced from practice" and the deficiency in cross-site comparison studies. As for current problems, the authors finally have discussion and draw a conclusion that firstly, ABMs should be constructed by the support of complex system theory. Moreover, the natural ABM/LUCC are supposed to explore the comprehensive human-natural interactions in land systems, to predict land system dynamics, and to analyze the consequences of land system change.
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    The Reconstruction of Cropland Area and Its Spatial Distribution Pattern in the Mid-Northern Song Dynasty
    HE Fanneng, LI Shicheng, ZHANG Xuezhen
    2011, 66 (11):  1531-1539.  doi: 10.11821/xb201111009
    Abstract ( 785 )   PDF (859KB) ( 1021 )   Save
    To simulate land cover change process and its climate effects, it is significant to construct historical land use and land cover change dataset with spatial information. According to "Cropland Taxes" and "the Number of Households" data recorded in historical documents, this paper speculates cropland area and population of each Lu (administrative region of the Northern Song Dynasty) during the mid-Northern Song Dynasty by analyzing some society factors of the Northern Song Dynasty, including land-use practices, taxation system, reclamation policies. Besides, this study selects slope, altitude and population density as the main driving factors of land use suitability degree and reconstructs the gridding spatial distribution pattern of cropland of the Northern Song Dynasty (at a 60 km×60 km resolution). The results are shown as follows. (1) The cropland area of the whole country in the mid- and late Northern Song Dynasty is about 720 million Mu, accounted for 40.1% of the north and 59.9% of the south; the population is 87.2 million, accounting for 38.7% of the north and 61.3% of the south; the territory cropland fraction is 16.6%, and per capita cropland area is 8.2 Mu. (2) The cropland fraction of the North China Plain, the Yangtze River Plain, the Guanzhong Plain, the plains of Hunan and Hubei, and the Sichuan Basin are larger while the that of the south of Nanling Ridges, Southwest China (except the Chengdu Plain) and southeast coastal regions of China are lower. (3) In terms of altitudes, we conclude that the cropland areas of low altitude, middle altitude, high altitude are 443 million Mu, 215 million Mu, and 64 million Mu respectively, and the corresponding mean cropland fraction are 27.5%, 12.6% and 7.2%. (4) As for slopes, we conclude that the cropland area of flat slope, slow slope, slope, steep slope are 116 million Mu, 456 million Mu, 144 million Mu and 2 million Mu respectively, and the corresponding mean cropland fraction are 34.6%, 20.7%, 8.5% and 2.3%.
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    Fluvial Incision Process and Its Tectonic Implications of Golmud River since Last Glaciation Maximum
    CHEN Yixin, ZHANG Mei, LI Chuanchuan, LI Yingkui, LIU Gengnian
    2011, 66 (11):  1540-1550.  doi: 10.11821/xb201111010
    Abstract ( 709 )   PDF (879KB) ( 564 )   Save
    The Golmud River originates from the Kunlun Mountains and drains into the Qaidam Basin on northern Tibetan Plateau. The Golmud River valley has experienced intensive tectonic movements since the Last Glacial Maximum, which deeply influenced the geomorphologic evolution of the river. In addition, well-developed fluvial terraces and sediments are preserved in the river valley and provide vital information for studying the environmental evolution in detail. Four terraces developed in the river valley since the Last Glacial Maximum, which may be responses to four tectonic uplift events. In Nachitai and Sanchahe sections, the incision rates of the four terraces are 9.33-3.33 mm/a (T4-T3, 16-13 ka BP), 12-5.5 mm/a (T3-T2, 13-11 ka BP), 1.0-0.33 mm/a (T2-T1, 11-5 ka BP) and 0.8-0.6 mm/a (T1, since 5 ka BP), respectively. The incision rate increased from 16-11 ka BP, and then it has been decreasing since 11 ka, which implies the tectonic uplift processes. The average incision rate of Xiaonanchuan since 5 ka BP is 4 mm/a. The rate is larger than that of Sanchahe and Nachitai, indicating that the tectonic uplift is more intensive in this region. The longitudinal section of the terraces indicates that the rates and depths of incision were the largest in Sanchahe section (62 m, 3.88 mm/a) and on the piedmont (46 m, 2.88 mm/a), while it was mild in Nachitai section (26 m, 1.61 mm/a). The deformation of the terraces suggests that the Yeniugou fault at Sanchahe and the Hongshigou fault on the piedmont have been active since the Last Glacial. The Kunlun river fault is a thrust fault, and its uplift rates started to rise at 16-13 ka BP, and peaked during 13-11 ka BP, and decreased after 11 ka BP.
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    Modern Sedimentation Rates of Fuxian Lake by 210Pb and 137Cs Dating
    WANG Xiaolei, YANG Hao, DING Zhaoyun, YANG Benjun, ZHANG Mingli
    2011, 66 (11):  1551-1561.  doi: 10.11821/xb201111011
    Abstract ( 540 )   PDF (868KB) ( 847 )   Save
    Based on GPS location, seven sediment cores were collected from different areas of Fuxian Lake. By analyzing the radionuclide profiles of 210Pb and 137Cs, we found that there were three obvious time markers of 137Cs in all the sediment cores, which corresponded to the onset of fallout in 1954, the maximum peak fallout in 1963 and the former Soviet Union's Chernobyl accident in 1986. Some sediment cores (FX1, FX3, FX5 and FX7) had the secondary peaks in 1975 or 1976 by the Chinese nuclear tests, verifying the rationality of this auxiliary time marker. On the basis of the 210Pb (CRS) dating, the ages were obtained in the past 150 years. As for dissimilar physical and chemical associations, diffusion characteristics for the two radionuclides (Pb and Cs), we interpreted the rationality of deviation by the two dating methods. In combination of the 210Pb and 137Cs dating results and historical data, we found that the modern sedimentation rates in different sediment cores (except FX6) of Fuxian Lake had a similar tendency, which can be marked off three stages: natural evolution stage, man-made disturbances stage and man-made transformation stage. In the short time-scale, human activities of historical periods had played a very important role in changing the sedimentation environment of the Fuxian Lake.
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    Holocene Aeolian Loess and Its Pedogenic Modification in the Upper Hanjiang River Valley, China
    PANG Jiangli, HUANG Chunchang, ZHOU Yali, ZHA Xiaochun, WANG Chaojian
    2011, 66 (11):  1562-1573.  doi: 10.11821/xb201111012
    Abstract ( 848 )   PDF (1202KB) ( 924 )   Save
    Loess-like sediments over the first level river terraces of the Upper Hanjiang River Valley between Yunxian and Yunxi were surveyed in detail and then sampled systematically. Pedogenic modification characteristics and the structure of soil profiles were observed in the field survey. Particle-size distribution, mineral assemblage, major elements and trace elements, magnetic susceptibility, CaCO3, micromorphology and OSL age were analyzed in laboratory and compared with Holocene loess-paleosol sequences in the Weihe River Valley. Results are shown as follows. (1) The loess-like sediments have aeolian features due to continuous accumulation of dust storms since the Late Pleistocene, with the profile structure TS-L0-S0-Lt-L1-AD. They are the same as the Holocene loess-paleosol sequences in the Weihe River Valley in these aspects, including stratigraphic structure, color, physical and chemical properties. (2) The dust storm sediments went through different degrees of pedogenic modification in different periods, namely weak pedogenic modification in the late Pleistocene, very strong pedogenic modification during the mid-Holocene and weaker pedogenic modification during the late Holocene. (3) It was cold and wet during the late Pleistocene (11500 a BP) and frequent dust storms led to the formation of Malan loess layer L1. It is a climate shift from cold-wet to warm-humid during the early Holocene (between 11500-8500 a BP) and dust storm activity gradually decreased to form a transitional loess layer Lt. It was warm and humid during the mid-Holocene (between 8500-3000 a BP), and dust storm sediments were strongly modified to form paleosol S0. It tended to be cooler and drier during the late Holocene (since 3000 a BP), and dust storms were obviously inrensified to form modern loess L0.
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    High Accuracy Surface Modeling of Soil Properties Based on Geographic Information
    SHI Wenjiao, LIU Jiyuan, DU Zhengping, YUE Tianxiang
    2011, 66 (11):  1574-1581.  doi: 10.11821/xb201111013
    Abstract ( 578 )   PDF (756KB) ( 448 )   Save
    There are two main limitations in surface modeling of soil property. One is the small number of available observations, and the other is the nonlinearity of the relationship between environmental variables and soil properties. It is still needed to research how high accuracy surface modeling (HASM) is combined with geographical information in soil property interpolation. This paper presented the method of HASM combined geographical information for soil property interpolation (HASM-SP). Based on types of soil, land use and parent rocks, we simulated the spatial distribution of soil properties of soil available P, Li, pH, alkali-hydrolyzable N, total K and Cr in a typical red soil hilly region. We compared the performance of HASM-SP, ordinary kriging (OK), ordinary kriging combined geographical information (OK-Geo) and stratified kriging (SK). The results showed that the methods combined with geographical information (HASM-SP and OK-Geo) obtained a lower estimation bias. Compared with the other three methods (OK-Geo, OK and SK), HASM-SP showed less MAEs and RMSEs. From the interpolation maps, much more details were presented in the HASM-SP maps of soil properties due to the abrupt boundary from spatial variation of geographical information. Therefore, HASM-SP can not only improve the interpolation accuracy but also characterize the spatial variation of soil property surface in the abrupt boundary, which can make the map consistent with the true geographical information. HASM-SP has great significance for enriching the theory of high accuracy surface modeling of soil property, and providing scientific evidence for the application of the soil management, precision agriculture and regional environment planning.
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