Table of Content

    25 October 2014, Volume 33 Issue 10 Previous Issue    Next Issue
    Orginal Article
    Transport networks, intraurban structure and system of cities: a Sino-US comparative perspective
    Fahui WANG, Yu LIU, Jiaoe WANG
    2014, 33 (10):  1289-1299.  doi: 10.11820/dlkxjz.2014.10.001
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    This article provides an overview of research on interaction between transport networks and human settlements from both the interurban and intraurban perspectives. Case studies from the US and China are cited to examine the commonalities and differences between them. In the interurban context, the regularity of systems of cities is represented in the popular rank-size model; and in the intraurban context, the regularity of urban structure is exemplified in the negative exponential density function. Both can be explained by the configuration of transportation networks that shapes the variability of location. Among other approaches, multiple centrality indices (for example, degree, closeness, betweenness, and straightness), developed from the space syntax theory and the complex network science, capture the location advantages across space. While several studies have examined the spatial patterns of centrality shaped by the railway and highway networks in China, one study explicitly confirmed the strong association between city sizes and centrality values based on the air transport network in China. There is a rich body of literature on the association of centrality and land use intensity in an interurban setting with an ample of case studies on cities in the United States and China. A case study in the United States shows that the variation of centrality indices explains the urban population density pattern better than the urban economic model. Recent work strives to identify what land use (or specific economic activity) values one type of centrality over others. For instance, a case study on commercial activities in Changchun indicates that specialty stores value various centralities most, followed by department stores, supermarkets, consumer product stores, furniture stores, and construction material stores; and specialty stores favor closeness most, department stores and supermarkets prefer betweenness, and consumer product stores value straightness most. Furthermore, based on a case study in China, the air passenger traffic flows between cities reflect the gravitations of cities by a particular transport mode, nodal attractions in cities reconstructed from the reverse gravity model are generally in line with their population sizes, and the analysis helps reveal the complimentary roles of multiple transportation modes in the growth or decline of cities. Based on another case study in Shanghai, the spatio-temporal patterns of intraurban traffic flows, detected from the location aware devices (LAD), reflect the underlying distinctive land uses. The study shows the great potential of using mobility data collected from LAD to model the rapid urban land use change in China and to help design meaningful policy intervention to mitigate traffic congestion. In summary, the interdependence between human settlements and transport networks offers a common thread integrating the traditional division of inter- and intra-urban studies. The Sino-US comparative examinations have important implications for public policy and urban planning practice in China and beyond.

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    Review and prospect of research on the spatial pattern of China's urban system
    Chao BAO, Xiaojie CHEN
    2014, 33 (10):  1300-1311.  doi: 10.11820/dlkxjz.2014.10.002
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    Creating a scientifically-sound spatial pattern of urban system is an important content of promoting the "new urbanization" strategy in China. In this article, we discuss the progress of research on the overall characteristics, evolution, and development mechanisms of the spatial pattern of China's urban system. These include the research progress on the spatial distribution and structure of China's urban system, the spatial pattern of city scales, the spatial pattern of functional structure, as well as the spatial pattern of urban network of China's urban system. This review concludes that although much research has been done on the spatial pattern of China's urban system based on socioeconomic development, further in-depth and improved research is still needed. Less research has been done on the spatial pattern of China's urban system based on ecological environment and natural resources security concerns, and this fails to meet the practical needs of urban development. Research on optimization theory and evaluation of the spatial pattern of China's urban system is overall insufficient. System simulation and optimization mode research is relatively weak. Accordingly, in addition to deepening and improving studies on current research themes, future studies should focus on the spatial coupling of the ecological security pattern, resource and environment pattern, and economic and social development pattern of China's urban system. The research on optimization theory, evaluation methods, system simulation models, and optimization modes and strategies of the spatial pattern of China's urban system should be highligted. Finally, an integrated system of theory and methodology on the spatial pattern of China's urban system should be developed.

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    Residents' subjective well-being and influencing factors in Beijing
    Yunxiao DANG, Wenzhong ZHANG, Jianhui YU, Li CHEN, Dongsheng ZHAN
    2014, 33 (10):  1312-1321.  doi: 10.11820/dlkxjz.2014.10.003
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    Residents in urban China are paying increasingly more attention to the quality of life and personal well-being with the improvement of living standards. Improving residents' quality of life is also an important target of urban development. Scholars have conducted research on subjective well-being from the perspective of psychology, sociology, and economics for a long time. However, only few geographic studies in China have addressed this topic. Among these studies, some were concerned with the evaluation method of happy city or happy region by building an evaluation index system, others focused on small scale case studies that examine the influencing factors of individuals' subjective well-being. These studies show that individual social attributes have significant impact on subjective well-being; subjective well-being is also influenced by socioeconomic factors such as crime rate and employment of a city or region. On the other hand, by reviewing the literature we found that geographers in western countries have conducted much research on the measurement, index system, and influencing factors of subjective well-being. Given the Chinese socioeconomic, policy, and institutional context of the past decades, it is important to examine the unique factors that affect subjective well-being of citizens in China, which has not been adequately covered by existing research. Based on the data from a large survey of 5732 participants conducted in 2013 in Beijing, this article develops an indicator system of individual subjective well-being; it also analyzes the subjective well-being of individuals with different social attributes and estimates the impact of relevant factors on subjective well-being with a multivariate linear regression model. Several conclusions are drawn as follows: (1) Individuals with diverse social attributes are significantly different in subjective well-being. The young and the old are happier than the middle-aged group of respondents. Family income has positive impact on subject well-being. However, people with highest family income are not the happiest. Individuals who are highly educated or have a big family are happier. Household heads, pensioners, high-rank managers of companies, and employees of state-owned enterprises are more satisfied with their lives. (2) The majority of the survey participants gave higher scores on life satisfaction but lower scores on happiness. (3) Policy and institutional factors have significant impact on individual's subjective well-being. Respondents with Beijing hukou feel happier and those living in commercial housing are happier than those living in residence provided by workplace or in affordable housing. (4) Increase of working or commuting time leads to lower happiness. (5) Respondents who changed residence once or twice in the last five years feels happier, but this is not the case with those who changed housing more than three times. Similarly, changing job makes people unhappy. (6) Individuals feel happier if they feel good about the living environment, national policy, personal health, and relative income.

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    Research on urban spatial structure in Beijing based on housing prices
    Fang WANG, Xiaolu GAO, Bingqiu YAN
    2014, 33 (10):  1322-1331.  doi: 10.11820/dlkxjz.2014.10.004
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    The development of housing market in Beijing has brought phenomenal changes to urban structures, and in recent years, soaring housing price has become a serious public concern. This paper explores the spatiotemporal evolution of housing prices using the spatial data of residential blocks in 2005 and 2012 in order to reveal its influencing factors, especially factors affecting the spatial structure of housing prices. Based on the analysis, this paper discusses the characteristics of such spatial structure and put forward some suggestions for urban planning and construction from the viewpoint of housing prices, which is a new perspective of urban spatial structure studies. The result of the analysis shows that housing prices increased overall, and particularly, the prices of subsidized housings for lower income population and regular housing increased much faster compared to higher-end housing. Spatial autocorrelation effect associated with housing price has become significantly stronger in 2012, especially in the central part of Beijing. The influencing factors of housing prices were analyzed using a multivariate linear regression model-the hedonic pricing model. In addition to the location factor, high property maintenance standard, good environment, well-developed transportation infrastructure, high-quality educational resources, and high availability of other public service facilities around the residential blocks can significantly increase housing prices. Multiple centers of high price housing have started to emerge in the past decade, such as the CBD, Zhongguancun, and Ya'ao districts. The Financial Street and Yuetan areas are the high value centers of housing prices. The areas around the south Sixth Ring Road, especially the Fangshan District, are the concentrated areas of lower price housing. This may eventually lead to social segregation of urban residents. Effective policies should be made to avoid this problem. In addition, the city should strengthen traffic infrastructure development and enhance the coordination of different facilities to influence the spatial pattern of housing prices and promote equal provision of urban social resources fundamentally.

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    Spatial and temporal evolutions of industries under the background of urban sprawl in Beijing
    Xinying JIAO, Wei LI, Zhuolin TAO, Zhonglei YU, Jinping SONG, Wenxin ZHANG
    2014, 33 (10):  1332-1341.  doi: 10.11820/dlkxjz.2014.10.005
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    With rapid economic development and urbanization, the urban area has been rapidly expanding and the urban spatial structure has experienced dramatic changes in the city of Beijing. The spatial distribution of industries is an important force to promote urban spatial structure change. This article explores the characteristics of the spatial and temporal evolutions of industries under the background of urban expansion. Spatial and temporal changes of 10 major industrial sectors in the Beijing metropolitan area for the periods 2004-2008, 2008-2012, 2004-2012 are analyzed and spatial distribution of industries for 2012-2020 is projected using an extended shift-share analysis model based on GIS. The theoretical assumption of the shift-share analysis is that small economies change in relation to a larger benchmark or parent economy in some definable and predictable ways. In this study, an extension of the original shift-share analysis model was made. The specialization and growth rate differentials in major economic sectors within a metropolitan area can be identified by making such extensions. While the shift-share analysis offers an analytic tool for revealing the spatial and temporal evolutions of industries, GIS provides an integrated technical environment for the implementation. The output data of different sectors at the county level were derived from the statistical yearbooks of Beijing for 2005, 2009, and 2013. The results show that industries have clearly shifted to the new towns, especially Shunyi, Tongzhou, Yizhuang, and Fangshan, and have extended in an arc to the south and the east; business and producer services agglomerate in the central city and spread in concentric rings outwards; transportation and storage and postal services expand along a number of axes; real estate development clearly diffuses outwards in all directions; and public services have begun to shift to the new towns, but high quality education, health care, and cultural resources are still concentrated in the central city area. Overall, the spillover of manufacturing industries is clear in Beijing. Real estate development and public services have expanded spatially as well. But business and producer services have no significant spatial diffusion. Compared with metropolitan areas of developed countries, the spatial evolution of industries in the Beijing metropolitan area is to some extent different. This study integrates geographic information system and extended shift-share analyses to characterize the spatial and temporal evolutions of industries and thus represents an improvement over previous studies that often focused on single industrial sectors. Moreover, it has overcome the limitations of previous analyses based on employment data. This study also has a number of deficiencies that need to be addressed in future work. First, uncertainties exist in predicting the future evolution of industrial space using the 2008-2012 data, primarily because of potential development policy change. Second, this study is limited to a county-scale analysis. In order to conduct an in-depth analysis of the spatial and temporal evolutions of industries, such research should be extended to the postal district or neighborhood scale. In addition, this study did not examine influencing factors and mechanisms of change. These should be explored in future studies.

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    Research progress in spatial dynamics of firms
    Jin SHI, Canfei HE
    2014, 33 (10):  1342-1353.  doi: 10.11820/dlkxjz.2014.10.006
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    Spatial dynamics of firms is a "microscopic" view of industrial dynamics in regional economies. This paper examines four theoretical frameworks of firm entry, exit, and relocation, namely neoclassical, behavioral, institutional, and evolutionary framework by situating them in the changing philosophy and methodology of economic geography in the western world over the past 60 years. (1) Firms in the neoclassical approach are "homo economicus" whose rule of decision making is profit maximization. Thus, firm entry is a function of expected profits, entry barriers, market risks, and opportunity costs of the entrepreneur. Firm exit is the result of market competition based upon productivity. Firm relocation is triggered by the readjustment of the "spatial margins to profitability" by a combination of pull and push factors of relocation. (2) Firms in the behavioral approach are "satisficers" characterized by bounded rationality and limited information. As a result, new firms might be founded by "innovators" who are alert enough to discover and exploit profit opportunities, but can also be "entry mistakes" if their founders have such motives as the desire for independence and the fear for unemployment. Firm exit is determined by the capability of the entrepreneur and the firm itself; the latter is usually measured by firm age and size. Firm relocation is analyzed by the "behavioral matrix" in which entrepreneurs differ in their ability to acquire and use information. (3) Firms in the institutional approach are embedded in four levels of institutions: informal institutions, formal institutions, governance structures, and resource allocation and employment. Thus, firm entry might be attributed to local culture and social networks, protection of property rights, government development packages and expenditure on public goods, regulation of product markets, personal wealth, and availability of local financial capital. Firm exit could be affected by local social networks, protection of property rights and contract enforcement, government subsidies and tax cutbacks, local protectionism, and labor laws. Firm relocation is a function of keep factors (for example, local social networks), push factors (for example, environment regulation), and pull factors (for example, development incentives, better contract enforcement, and less labor unionization). (4) Firms in the evolutionary approach have "routines" subjected to "selection" by the market. Firm entry is through both contagious diffusion of routines and spin-off dynamics. Firm exit might be influenced by pre-entry experiences whose impact varies over the industry life cycle. Firm relocation is strongly constrained by path dependency and spatial lock-in. This article discusses the problems of current research in terms of theories, data, and methods and proposes suggestions for pushing the frontier of research. It argues that the role of space in firm dynamics shall be further theorized, and the quality of firm-level database and techniques of model-building shall be improved. Compared to research in the West, China lags behind in the field of spatial dynamics of firms both theoretically and empirically. In the catch-up process, western theories should be tailored to China’s unique political regime, economic transformation, and social and geographical background to better guide empirical studies.

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    Regional differentiation and decadal change of precipitation in China in 1960-2010
    Yanjiao WANG, Feng YAN
    2014, 33 (10):  1354-1363.  doi: 10.11820/dlkxjz.2014.10.007
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    Based on precipitation data from 1840 meteorological stations in China in 1960-2010, this study examines the regional differentiation of precipitation and characteristics of its change in the recent 50 years. Using the empirical orthogonal function (EOF) and rotated EOF (REOF) methods, precipitation in China is divided into 11 regions, which are grouped into four areas according to their geographic locations: East China area (North China, Huanghuai and Jianghuai, the middle and lower reaches of the Yangtze River, and Jiangnan and South China regions), Northwest China area (Midwest Inner Mongolia, western part of the Northwest China, and eastern part of the Northwest China regions), Southwest China area (southeastern part of the Southwest China, western part of the Southwest China, and northeastern part of the Southwest China regions), and Northeast China. Compared with the results of previous studies, precipitation regions derived with the REOF method in combination with detailed long time series precipitation data are consistent with the regional differentiation of actual precipitation and the climate division of China. The analysis shows that precipitation in the East China area changed in the late 1970s, from the late 1980s to the early 1990s, and in the beginning of the 21st century respectively, featuring recurrent south-north shifts of the rain belt in both directions, which were mainly influenced by the interdecadal variability of the East Asian summer monsoon and atmospheric circulation. Precipitation in the Northwest China area experienced a major change in the mid-1980s. The western part of the Northwest China area became wet compared to the dry period in the previous years, whereas the eastern part of the area became dry compared to the previous wet years. The decreasing precipitation in the eastern Northwest China area was related to the continually weakening of the East Asia summer monsoon, while the increasing precipitation in the western Northwest China area were mainly due to the anomalous high moisture transport from the Arabia Sea and the Caspian Sea. Precipitation in the Northeast China area underwent similar abrupt changes in the early 1980s and the late 1990s respectively-it changed from the previous near normal level to high in the early 1980s, and from high to low in the late 1990s. The changes were influenced by the East Asian summer monsoon on the one hand, and related to the anomalous moisture transport form the Northwest Pacific Ocean on the other. Evident changes in precipitation have been detected over each region in the Southwest China area-precipitation changes over the western and northeastern parts of this region were in opposite directions before 2000. Precipitation in the Southwest China area is not only influenced by the terrain of the Tibetan Plateau, but also affected by the East Asian monsoon and the subtropical high, which cause complicated changes in precipitation of the area.

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    Applicability analysis of the TRMM precipitation data in the Sichuan-Chongqing region
    Tao JI, Hua YANG, Rui LIU, Tairong HE, Jianfeng WU
    2014, 33 (10):  1375-1386.  doi: 10.11820/dlkxjz.2014.10.009
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    Precipitation data is often needed for hydrological, meteorological, ecological, and other environmental and geographic applications. Currently there are mainly two sources of precipitation estimates: observation at meteorological stations and remote sensing data. However, a large number of studies has demonstrated that measurements at conventional meteorological stations are point data and they cannot reflect the spatial variation of precipitation effectively, especially in areas of more complex terrain. Remote sensing technology, on the other hand, is able to produce reasonably high resolution gridded precipitation fields. Precipitation products obtained by satellites have been widely used in previous studies in the world. The Sichuan-Chongqing region is a typical area with complicated terrain and climate characteristics. The meteorological stations are very unevenly distributed in this region, especially in the western area. Precipitation estimation using satellite data provides potential alternatives to precipitation measurements in this region. In this study,the performance of the TRMM (Tropical Rainfall Measurement Mission) 3B43 monthly precipitation data over 2000-2011 was evaluated in the Sichuan-Chongqing region with rainfall records from 72 meteorological stations at different time intervals. The influence of elevation and slope on the verification result was analyzed at the monthly scale. Finally, principal component analysis was used to compare the effects of elevation and slope on the accuracy of TRMM 3B43 precipitation estimates. The results show that: (1) Regional average annual precipitation estimated by TRMM 3B43 is higher than the observed data from meteorological stations by 5.38%, and the eastern area estimation results are less accurate than the western plateau. Goodness of fit of seasonal precipitation between TRMM 3B43 estimates and observed data is high, but varies between the seasons—the goodness of fit of spring precipitation is higher than other seasons. Correlation between observations at the 72 stations and TRMM 3B43 estimates is high and shows little numerical biases in the whole study area at the monthly scale. (2) For individual stations, at most stations the correlation coefficients are reasonably high and the estimation biases are small, but the correlation coefficient at the Xuyong Station is comparatively low and the estimation biases at the Xiaojin Station, Yaan Station, Leibo Station, Yanyuan Station, and Panzhihua Station are comparatively high. (3) Compared with slope, elevation has greater influence on the accuracy of TRMM 3B43 estimates, which can be characterized by a cubic nonlinear relationship. With the increase of Elevation, R shows an increasing trend and |Bias(%)| increases-decreases-increases. (4) The influence of slope on the accuracy of TRMM 3B43 estimates is more complicated. Generally speaking, slope significantly affects the accuracy of TRMM 3B43 estimates

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    Climate variation and glacier response in the Bogda region, Tianshan Mountains
    Yi HE, Taibao YANG
    2014, 33 (10):  1387-1396.  doi: 10. 11820/dlkxjz.2014.10.010
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    Under the background of global warming in recent decades, glaciers on Earth have been rapidly melting. Mountain glaciers in China have also changed dramatically. The changes in mountain glaciers have impacts on water resources in the northwestern arid area of China, and therefore monitoring change of mountain glaciers is very important. The glacier meltwater in the Bogda Peak region is a reliable source of water for the Aries River Basin, the Turpan-Hami Basins, and Basin Chaiwopu, and the scientific value of such research is also significant. This article summarizes the status of research on this subject. Based on the 1972 Landsat MSS, 1990 Landsat TM, 1999 Landsat TM, and 2013 Landsat ETM+ remote sensing data, glacier information of four time periods in the study area were extracted by using visual interpretation combined with digital processing of satellite images and analysis in GIS. The climate data in the surrounding area were analyzed using linear regression, Mann-Kendall abrupt test, and Morlet wavelet analysis. The relationship between glacier retreating and climate warming was also analyzed in this study. The main results show that: (1) The annual mean temperature and precipitation had an increasing trend, with rates of 0.19℃·10a-1 and 12.4mm·10a-1; annual temperature increased since 1990, while annual precipitation increased since 1985. Morlet wavelets of annual temperature mainly had a 8 to 10 year cycle, while annual precipitation cycle was not clear. The warming trend was clear in this region, but rainfall has shown little change. (2) During 1972-2013, glacier area of the study region decreased by 46.71±1.32 km2, accounting for 23.87 ± 0.67% of the total. The average annual withdrawal rate was 0.66 ± 0.02%·a-1. Glacier retreat rate was low in 1972-1990, at 0.44 ± 0.03%·a-1. But this rate has increased in the last 20 years, to 0.78 ±0.09 %·a-1. The retreat rates of Sigonghe No.4 glacier and Black Trench No.8 glacier have accelerated in recent years. (3) Characteristics of the spatial structure of the glaciers were analyzed based on the fractal theory and the research predicts that the ablation rate of glaciers in the study area will remain high. (4) Compared with glacier retreat in other regions of China, glaciers in the Bogda area show a similar trend of change. (5) Prior to 1990, the important meteorological factors that influenced the change of Bogda region glaciers were temperature and precipitation, but temperature has played a more important role in affecting glacier retreat after 1990.

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    Geomorphology Research
    Evolution of glacial trough and influence factors of the Qingshui Valley in Luoji Mountain, Sichuan Province
    ZHANG Wei, HE Daiwen, LIU Libo, LIU Beibei, RI Haibujiere, LI Yincai
    2014, 33 (10):  1397-1404.  doi: 10.11820/dlkxjz.2014.09.011
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    Luoji Mountain located at the southeast margin of the Qinghai- Tibet Plateau is one of the typical mountains in China where Quaternary glacier relics exist. The evolution of glacier landforms in the area plays an important role in the study of regional environmental change. In the Qingshui Valley on the east slope of the Luoji Mountain, two sets of ancient glacial trough valleys, namely the inner trough valley and lateral trough valley, are preserved. The inner trough valley is relatively intact. However, the lateral trough valley between 3450 m and 3600 m in the shady slope is incomplete. Based on field investigation and model analysis, this study examines the evolution of the glacial trough valley. The model analysis shows that the A and B parameter values vary between 1.3101-15.2064 and 0.9695-3.2965 respectively and these values first increase and then decrease with decreasing altitudes. Both values indicate that the form of the glacial trough valley is atypical. The field investigation and model analysis indicate that lithology and headwater erosion have contributed to the shape of the trough valley. This study applied the ESR dating method to define the high and low moraine in the through valley. The result shows that the high lateral moraine was formed in ~58-84 ka BP, which was in the early stage of the last glacial cycle, corresponding to the Marine Isotope Stage 4 (MIS4). The low lateral moraine was formed in 13-17 ka BP, which was during the last glacial maximum (LGM), corresponding to MIS 2. During the last glacial cycle two glaciations developed two sets of trough valleys respectively, that is, the early stage of the last glacial cycle contributed to the formation of the lateral trough valley, and the late stage of the last glacial cycle contributed to the formation of the inner trough valley. The glacial sequences in the Qingshui Valley also show that the glacial activities took place here accorded with other mountains in the surrounding areas of the Qinghai-Tibetan Plateau.
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    Orginal Article
    Impact of land conversion on rural systems in typical agricultural counties of eastern plain area, China
    Fang FANG, Yansui LIU, Yurui LI, Haoguang LIANG
    2014, 33 (10):  1405-1413.  doi: 10.11820/dlkxjz.2014.10.012
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    Revealing the relationship between land conversion and rural development is necessary for the healthy and integrated development of urban and rural areas. Taking two typical agricultural counties in the eastern plain area of Shandong Province, China as study cases, this article dissects the impact of land conversion on rural systems through the analysis of evolution of land conversion and rural system at different socioeconomic development stages. The results show that: (1) with the change of county economic development from low to advanced stage, the scale and ratio of land conversion increased, while the overall development trend of the rural systems was positive, with increasing comprehensive rural development index (E) values from 0.295 to 0.798 and 0.197 to 0.700 between 2000 and 2008 in Yucheng City(county-level city) and Huantai County, respectively, with fluctuations in some years; (2) the extent of impact of land conversion on rural system changed from weak to strong gradually, and the increased ratio of land conversion led to dramatic changes of some elements of the rural systems. Among these, the sensitivity of the rural economic and social subsystems to land conversion was relatively high compared to the environmental and resource subsystem. The focus of controlling land conversion and rural transformation in plain agricultural area is to build the protection mechanism for rural population transfer and the economies of scale of farmland management, regulate land use planning and management, and improve the capacity of influence of counties

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    Spatial-temporal characteristics of soybean production potential change under the background of climate change over the past 50 years in China
    Xiaofeng ZHANG, Hongzhi WANG, Luo LIU, Xinliang XU
    2014, 33 (10):  1414-1423.  doi: 10.11820/dlkxjz.2014.00.013
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    Soybean is one of the most important grain and oil crops in China. With the growth of population and the improvement of people's living standard, demands for soybean products have been increasing. At the same time global climate change has brought both beneficial and detrimental effects to soybean production, depending on the geographic areas. Using the 2010 remote sensing monitoring data of cultivated land distribution and long time series meteorological and soil data, soybean production potential in China was calculated using the AEZ model for the period from 1961 to 2010. Solar radiation, temperature, water, CO2 concentration, plant diseases and insect pests, agricultural climate restrictions, soil, terrain, and other factors were taken into consideration in the model. This study simulated long-term change of soybean production potential in China from 1961 to 2010 and analyzed the spatial-temporal characteristics of this change under the background of climate change. The results are that: (1) Significant difference was found in the spatial distribution of soybean production potential in China over the study period—there was an increasing trend from south to north and west to east. The high potential zones were Northeast China Plain, Middle-Lower Yangtze River Plain, and Huang-Huai-Hai River Plain. (2)In the recent 50 years, China's soybean suitable planting areas increased continuously, while the mean soybean production potential steadily declined. The total potential yield of soybeans nationwide decreased at the beginning and then increased—in the 1970s the total potential yield of soybeans reduced by 2.181 million tons compared to that in the 1960s. It then showed a trend of continuous growth from the 1970s to 2000s, and the amount gradually became larger. From the 1970s to 2000s the total potential yield of soybeans increased by 5.3 million tons. (3) In different regions of China soybean production potential experienced different changes. From the 1960s to the 1970s the total potential yield of soybeans in the Middle-Lower Yangtze River Plain ranked first in China. In the 1980s, the total potential yield of soybeans in Northeast China Plain had a spectacular increase and exceeded the Middle-Lower Yangtze River Plain and became number one in the country. The Huang-Huai-Hai River Plain ranked third. Since the 1970s, the total potential yield of soybeans continuously declined to 65.87 million tons in the 2000s and it was 2.85 million tons lower than in the 1960s. This study reveals the spatial-temporal characteristics of soybean production potential change over the past 50 years in China, which has important scientific significance for the planning of soybean planting, efficient utilization of climate resources, and achieving high and stable yield of soybeans.

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    Long-term effects of fertilization on aggregates distribution and total nitrogen stock in a reddish paddy soil of subtropical China
    Wenjun LI, Baofa PENG, Qingyu ZENG, Yali WANG, Fengxi LI, Zhitao QING
    2014, 33 (10):  1424-1432.  doi: 10.11820/dlkxjz.2014.10.014
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    Fertilization greatly influences soil structure and nutrients accumulation in soil aggregates. In this study, the effects of long-term fertilization on aggregates composition and total nitrogen stock in a reddish paddy soil in the subtropical area of China were investigated. The fertilization treatments included CK (without fertilization), NK (nitrogen and potassium fertilizer application), NPK (balanced application of nitrogen, phosphorous, and potassium fertilizers), LOM (combined application of NPK and 30% organic manure fertilizers) and HOM (combined application of NPK and 60% organic manure fertilizers). Undisturbed soil samples in two layers were collected and then separated into five aggregate-size classes (>5 mm, 2~5 mm, 0.5~2 mm, 0.25~0.5 mm, <0.25 mm) by the dry sieving method. The amount and storage of nitrogen in each aggregate fraction were measured. The results indicate that the >5 mm blocky fraction was the dominant aggregates component, accounting for 65.7%~83.4% of dry soil mass in the two layers. It sequestrated 63.1%~82.7% of the total nitrogen in the soils and is considered the major carrier of soil nitrogen. Deeper in the soil, the content of >5 mm blocky fraction increased, while the percentages of the other aggregate-size groups decreased. For each soil layer, the contents of soil total nitrogen in different sizes of soil aggregates were significantly different and increased in the order of >5 mm, 2~5 mm, 0.5~2 mm, 0.25~0.5 mm, and decreased from 0.25~0.5 mm to <0.25 mm. However, the total nitrogen storage value first decreased and then increased and the minimum value occurred in the size group of 0.25~0.5 mm. Compared to the CK treatment, long-term fertilization was in favor of increasing the proportion of aggregates in the size group of 0.25~5 mm, while reducing the aggregate fractal dimensions. Moreover, the total soil nitrogen contents and storages in 0.25~5 mm aggregates and in the whole soils were increased significantly (P<0.05) after fertilizer application and the effects show an increasing sequence of NK<NPK<LOM<HOM. There was a significant positive correlation between the contents of 2~5 mm aggregates and total nitrogen storages in the soils, suggesting that the newly enriched organic nitrogen mostly appeared in 2~5 mm aggregates. Overall, in comparison with the plow pan, the amounts and total nitrogen contents of different aggregates in the plough layer were more sensitive to fertilization. The NPK fertilizers mixed with organic manure application greatly (P<0.05) promoted the total nitrogen storages in the plow pan and the whole soil layers when compared to single chemical fertilizer application and can be considered the best fertilization mode for improving soil structure and nitrogen fertility and that can be widely applied in the reddish paddy soil distrribution areas in subtropical China.

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