Table of Content

    26 March 2018, Volume 37 Issue 3 Previous Issue    Next Issue
    Perspectives and Contention
    Inheritance and innovation of Human and Economic Geography: Responsibilities of young scholars
    Mingxing CHEN, Suhong ZHOU, Shenjing HE, Chao YE, Mingfeng WANG, Wei SUN, Kaiyong WANG, Yanjun LIU, Shengjun ZHU, Haitao MA, Huasong YAO, Renfeng MA, Hua ZHANG, Jianhui YU, Kang WU, Fenglong WANG, Gengzhi HUANG, Rongqin ZHAO, Qing HAO, Chunla LIU, Jie ZHENG, Meng LIU
    2018, 37 (3):  449-472.  doi: 10.11821/dlyj201803001
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    On January 27-28, 2018, the Youth Forum of Human and Economic Geography and the 2nd Youth Forum of Key Laboratory of Regional Sustainable Development Modeling, Chinese Academy of Sciences were successfully held in China National Convention Center. The theme of the Youth Forum is "Inheritance and Innovation of Human and Economic Geography: Responsibilities and Actions of Young Scholars". The academicians, predecessors and heads of departments who came to the venue all expressed their encouragement, support and care for the faster and better growth of young talents. Under such a background, with the theme of this youth forum, it is imperative for young scholars to inherit and innovate humanities and economic geography in a new era. Young scholars should pursue the spirit of geographers, focus on the responsibilities and actions of young scholars, and show thinking and demeanor of young geographers of humanities and economics.

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    Review and Monograph
    A comprehensive study of innovation from land type to physical regionalization: The geographical thought and academic contribution of Ni Shaoxiang
    Yansui LIU
    2018, 37 (3):  473-479.  doi: 10.11821/dlyj201803002
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    Prof. Ni Shaoxiang was born in Wuxi city, Jiangsu province in June 1939. He attained his bachelor's degree from the Department of Geology and Geography, Peking University in 1964, and his master's degree from the Department of Geography, East China Normal University in 1967. He was an outstanding geographer who enjoyed great national reputation in the scientific community. He worked as a teacher at Nanjing University for more than 10 years, and pursued his study on remote sensing and land resources at the Department of Geography, Reading University in 1983-1985. From 1994 to 2016, he engaged in teaching at the Faculty of Geography, Nanjing Normal University. In more than 50 years of scientific research and education career, Prof. Ni has made remarkable achievements in various fields of geography, including natural geography, geo-analysis of remote sensing, and natural resources evaluation, through unswerving work, extensive study and pioneering research. He has presided over or participated in more than 10 national, ministerial and local key research projects, and won multiple prizes including Scientific and Technological Advancement Award by the Ministry of Education, Scientific and Technological Advancement Award by Jiangsu province, Scientific and Technological Advancement Award by the former State Bureau of Land Administration, Philosophy and Social Science Outstanding Achievement Award by Jiangsu province, and National Award for Outstanding Geography Book. He was also awarded the Outstanding Scientific and Technological Workers of China Society of Natural Resources, the Outstanding Scientific and Technological Workers of Jiangsu province, the Excellent Subject Leader of Universities in Jiangsu province, the Excellent Postgraduate Supervisor of Jiangsu province, etc. The geographical academic thought and achievement of Prof. Ni can be summarized in four aspects: land type and land evaluation, resource utilization and protection, environment remote sensing and grassland locust, and integrated physical geography. He has made great contributions to the discipline construction, personal training, and academic exchange of China's land resources science and integrated physical geography.

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    Research on urban space fragmentation
    Peijuan ZHU, Qingyun HE, Xiang ZHU, Shuqiang CUI, Xiaoshuang WU
    2018, 37 (3):  480-494.  doi: 10.11821/dlyj201803003
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    Spatial fragmentation is an objective phenomenon in the evolution of urban space, which is characterized by the fragmentation of urban space unit, the strengthening of space segmentation, the weakening of spatial relations and the decline of the overall function of space. Spatial fragmentation has the characteristics such as the closure of space form, the barrier of spatial contact and the mismatch of spatial functions, which should be great obstacles to the improvement of urban quality and sustainable development. The study of urban space fragmentation is a new hot spot of urban spatial pattern and process research. "Space fragmentation" is an extension and deepening of the concept of "landscape fragmentation", which can help to study the city's complex giant system from a more integrated and holistic perspective. The study of "spatial fragmentation" should follow the analysis framework of "pattern process characterization, formation mechanism analysis and regulation mode design", and discuss the concept, characteristics, measure, mechanism, dynamic simulation and control mode of urban space fragmentation. The method of integrating landscape index, spatial syntax, multi-agent scene simulation and geo-informatic spectrum should be adopted, and a comprehensive analysis of multi-disciplinary integration should be carried out. The fragmentation measure of urban space can be divided into pattern measure, effect measure and risk measure and the global scale index and the type scale index can be used to characterize it. The formation mechanism of urban space fragmentation can be analyzed from the evolution of self-organization, the evolution of his organization and the co-evolution of self-organization and his organization based on factor organization, behavior subject and system structure, etc. The dynamic simulation of urban space fragmentation can be carried out from the two aspects of "natural development" and "regulatory intervention". The mode of urban space fragmentation can be divided into three modes: preventive regulation, patching regulation and integrative regulation. On the basis of defining the concept and characteristics of urban space fragmentation, this paper clarifies the contents and methods of urban space fragmentation research. The theoretical analysis framework of urban space fragmentation research is preliminarily established to provide theoretical guidance and method support for urban space structure from fragmentation to sustainable development.

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    Spatial and temporal patterns of evolution of global trade networks during 1985-2015 and its enlightenment to China's geostrategy
    Xiaorong JIANG, Yongchun YANG, Shenglan WANG
    2018, 37 (3):  495-511.  doi: 10.11821/dlyj201803004
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    The paper, from the perspective of social network, explores the spatial patterns and evolutionary characteristics of the global trade network and focuses on the Chinese community ownership and their strategic implications by adopting social network indexes, including centrality, community classification and structure entropy. The results show that: (1) The structure of global trade network evolved towards complexity, specifically shifted from "one super state and more powerful countries" towards"multi-polarization". The collective rise of developing countries has weakened the monopoly position of traditional European and American countries in the network, leading to increasing complexity of the network structure. (2) Community evolution of the global trade network has experienced the dominant stage of the developed countries, the budding stage of the Asian region, the separated stage of the Asian Community and the fourth stages of "ripartite confrontation". During the evolution, China has gradually moved from being dominated to the center of the stage. (3) The diversification of trade market is a common characteristic of foreign trade countries. In the process of global market segmentation, China, the United States, and Germany gradually formed a relationship of "dislocation competition", and their core interests are concentrated around the surrounding areas. (4) The areas of Asia-Pacific Region, Middle East, Africa and Latin America have become the play field of China to compete other powers for local trade markets. Currently, the Asia-Pacific market is the preferred market for China's global trade, and China should extend the market to the Middle East, Africa and Latin America through "Silk Road Economic Belt and 21st Century Maritime Silk Road", In this way, economic advantage can be transformed into global strategic influence. Meanwhile, direct conflicts and confrontations with the core interests of the United States should be avoided.

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    Spatio-temporal evolution characteristics and mechanism of railway efficiency in China
    Binquan LIU, Wei WU, Qin SU, Lulu ZHANG
    2018, 37 (3):  512-526.  doi: 10.11821/dlyj201803005
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    Railway is one of the most important components of the integrated transportation system. A functional and efficient railway system can be conducive to sustainable development of society and economy, thus highlighting the importance of studies on rail efficiency. In this paper, we study the spatio-temporal evolution of China's railway transportation efficiency during 2005-2013 using the ultra-efficient SBM model and Malmquist index method. Hence, the characteristics and influencing mechanism of railway efficiency in China are also analyzed. The results are as follows: (1) the SBM model analysis of 18 Chinese rail bureaus indicates that rail efficiency increased from 0.724 to 0.778 due to a series of measures taken by the governments in recent years, such as reorganization, deregulation, and innovation. Scale efficiency increased by 1.93% per year and technical efficiency by 0.27% per year, indicating scale efficiency's major influence. We also find that the gap between 18 bureaus' efficiency narrowed in 2005-2013, standard deviation dropped from 0.287 in 2005 to 0.23 in 2013, and the coefficient of variation dropped from 0.396 to 0.295. (2) The spatial distribution pattern of railway transportation efficiency suggests that the railway system in the eastern region is more efficient than that of the central region, which, in turn, is more efficient than that of the western region. In addition, there are differences in the spatial distribution of the internal transport efficiency in the high-, medium-, and low-value areas, while the types of rail efficiency are also different. According to the characteristics of the railway bureaus' efficiency change, the 18 railway bureaus can be divided into three types: equilibrium, fluctuation, and growth. (3) Through the analysis of railway evolution, we find that the construction of large-scale high-speed railways in recent years has not caused significant changes in transport efficiency and productivity. (4) From the perspective of transportation geography, the location conditions, resource potential difference, topography, and urbanization pattern affect the spatial pattern of transport efficiency and its evolution.

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    The classification of transportation function of China's coastal ports based on cargo structure
    Wei WANG, Chengjin WANG, Fengjun JIN
    2018, 37 (3):  527-538.  doi: 10.11821/dlyj201803006
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    As an important part of a comprehensive transportation system, ports are considered an open window and bridge for countries and regions. The transport functional structure of ports has become a research focus of port geography. With the rapid expansion of high energy-consuming industries in China, the proportion of heavy industry has been rising remarkably. Therefore, it becomes an important issue to classify the transport function of ports from the perspective of cargo structure. In this paper, we choose coastal ports in China as the study subject. Based on the throughput of each type of cargo in 2013, we launch our research from three aspects: comprehensiveness or specialization, function scale dimension, and function status dimension. We also explore the relationship between comprehensiveness/specialization and the scale of port throughput. In this way, we consider not only the cargo structure of port itself, but also the position and function of each port in each cargo transportation system. This research finds that there is a weak correlation between port's scale and its comprehensiveness/specialization. The larger the scale is, the more significant the comprehensive characteristics are, whereas, the more prominent special characteristics are. Specialized ports are concentrated in the Pearl River Delta and areas around the Bohai Bay, and comprehensive ports are distributed in the Yangtze River Delta and southeast coast of China, while general ports are mainly located in the areas around the Bohai Bay, the Pearl River Delta and southwest coast of China. Bulk cargo is the main transport function of coastal ports in China, such as coal, metal ore, oil, and mineral building materials. Especially, coal plays an important role in most of coastal ports, and it is also the core element for the formation of port's specialized function. The spatial distribution of goods as the main cargo and superior cargo are not the same. Coastal ports in China can be divided into six types according to whether it has prominent function and its level of comprehensiveness/specialization. They are comprehensive ports with no prominent functions, specialized ports with no prominent functions, general ports with no prominent functions, comprehensive ports with prominent functions, specialized ports with prominent functions, and general ports with prominent functions. This study can enrich the theory of transportation geography, and we hope it can provide guidance for the construction and layout of coastal ports in China.

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    Inter-city difference and influencing factors of residents' subjective well-being: A study based on multilevel modelling
    Yunxiao DANG, Wenzhong ZHANG, Li CHEN, Dongsheng ZHAN
    2018, 37 (3):  539-550.  doi: 10.11821/dlyj201803007
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    During the last three decades, China has been marked by a remarkable economic growth, however, the greatly enriched material life did not promise Chinese an equal level of happiness. It has been proved that Chinese subjective well-being has been decreasing during the progress of high-speed urbanization. Scholars in Western world have conducted abundant research in influencing factors of residents' subjective well-being and evaluation of happy city. There is lack of studies aimed at Chinese residents, especially the systematic analysis of the influence by geographical background effect posed on the residents' subjective well-being. Taking all the prefecture-level cities in the Bohai Rim area as a case study, based on large sample survey questionnaires, objective statistics and census data, this paper analyzed the spatial distribution of subjective well-being at inter-city scale. Happiness function improved by multilevel modeling and GIS-based spatial analysis method are also applied to analyze the influencing factors of residents' subjective well-being. The conclusions are as follows: (1) There is significant disparity of residents' subjective well-being between cities. Most of the cities with more happy samples are in Liaoning province, while those with more unhappy samples are found in the majority of cities in Hebei province except Zhangjiakou and Chengde. (2) Urban scale and economic development are negatively related to residents' subjective well-being. People living in the biggest city are most unhappy with life, however, the high income can weaken the unhappiness. (3) Environment pollution has reduced the residents' subjective well-being, while positive evaluation of natural environment is helpful to improve residents' happiness. (4) Social security and human environment are positively related to the subjective well-being. The widening wealth inequality and urban diseases, such as pollution, traffic jam and housing shortage, should be responsible for the lowest degree of subjective well-being of residents living in the biggest cities. Even so, people are more likely to live in big cities. One possible reason is that the individual may be willing to trade off the subjective well-being for other things including high income, social status and accomplishments. Furthermore, individuals may prefer to take actions enabling to achieve the long-term desires and goals, although some of them could make them less happier at present.

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    The influence of cross-border roads on spatio-temporal connection in the city integration areas: Guangzhou-Foshan case
    Huiling CHEN, Xiaoshu CAO, Feiwen LIANG, Hengyu GU
    2018, 37 (3):  551-563.  doi: 10.11821/dlyj201803008
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    Urban integration can be defined as some stage of adjacent cities development in the region, and transport is an important basis for generating the integration effect. This paper analyzes the spatio-temporal structure characteristics of the Guangzhou-Foshan region and the influence of cross-border roads construction on spatio-temporal connection between Guangzhou and Foshan by using Space Syntax and time-space map method. Findings suggest that the polarization pattern is presented within the Inner Ring Road of Guangzhou in 5 km and 10 km scopes, and the central agglomeration is obvious in 20 km and 100 km scopes based on the integration value in Guangzhou-Foshan model. The time map of Guangzhou-Foshan shrinks significantly in the east-west direction. After the planned roads became passable, the closer the street is to the boundary, the greater the range-displacement is. The time cost of southern Guangzhou city and Nanhai district of Foshan city, Shunde would improve significantly. The planned roads are conducive to improving the overall level of road network accessibility on different scales, which shunt the traffic flow of the western Guangzhou-Foshan roads, Chencun bridge and Yushan west road etc. Compared with the previous urban integration studies, this paper identifies the city grade difference and traffic potential on different scales and makes the space-time transformation of geographical space for Guangzhou-Foshan by using space syntax and time-space map method. These conclusions could be used as a reference for city function integration in the future and provide a new dimension and perspective for the related research.

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    The diversity of different groups' job-housing patterns and their impact factors under the background of institutional transformation: A case study of Guangzhou, China
    Jiting ZHANG, Suhong ZHOU
    2018, 37 (3):  564-576.  doi: 10.11821/dlyj201803009
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    Job-housing relationship is one of the most important topics in urban studies. Because of the institutional transformation in China, people who work inside-system or live in urban areas may enjoy more welfare than those who work outside-system or live in rural areas, which makes the social differentiation unique. Dividing people into groups based on attributes related to institutional transformation and investigating what influences different groups' different job-housing situations can help to understand the internal mechanism of how the job-housing situations form in urban China. Mainly according to the result data of a questionnaire with a sample size of 1029, which was finished in Guangzhou in 2016, with the help of the point of interest and the road distribution data of Guangzhou in 2014, as well as the sixth census data of Guangzhou, two-step cluster and multinomial logistic regression are employed to figure out the mechanism. After clustering, three typical job-housing models were defined according to job-housing distance as well as the location of working and living place, and three social groups were defined according to residents' socioeconomic status. And then multinomial logistic regression was employed to compare the different reasons that influence different groups' job-housing situation. The results show that compared to the job-housing balance group, the outside-system group who have steady jobs try to achieve the highest comfort and convenience with the lowest living cost and they are willing to bear long commute for better living condition, so their job-housing models are influenced by the built environment mostly. When it comes to inside-system group, different from the outside-system group, on the one hand, they live in the unit community in the past, so they are used to the close-knit communities, and influenced by community environment obviously, on the other hand, they are influenced by social characters obviously, including marital status and the number of students in the family. The group of people without steady jobs are those who engage in business or have retired and get an informal job again. They have the highest freedom while deciding where to work and where to live, so their decisions about job-housing location are only slightly influenced by some factors about built environment, and the job-housing balance ratio of this group is the highest. This research tries to figure out the mechanism of how different social groups determine their job-housing location in the context of China's unique institutional transformation, and act as references to urban planners and policy makers while putting forward some advice to optimize it.

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    Canonical correspondence analysis of hotels' carbon emission efficiency in Wutai Mountain scenic area
    Zhanhong CHENG, Jiao XU
    2018, 37 (3):  577-592.  doi: 10.11821/dlyj201803010
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    It can provide a reference for the implementation of energy-saving and emission-reducing to measure hotels' carbon emission efficiency. Firstly, the buildings area, rooms and staff number of 28 hotels were taken as the input indicators, and water consumption, power consumption and coal consumption were taken as the output indicators in Wutai Mountain scenic area. Hotels' carbon emission efficiency was calculated by Data Envelopment Analysis. Secondly, the relationship between carbon emission efficiency and key indices was studied by Canonical Correspondence Analysis (CCA) and Two-Way Indicator Species Analysis (TWINSPAN). The results showed that: (1) 9 hotels' technical efficiency was fully effective, 15 hotels' pure technical efficiency was effective, and 9 hotels' scale efficiency was effective. (2) TWINSPAN divided all hotels into four groups. Group I had 9 hotels, accounting for 32% of the total number of hotels in this study, whose three efficiency values of carbon emissions were all 1, so they belonged to the full efficiency group. Group II consisted of three hotels, accounting for 11%. They had higher carbon emission efficiency, but there was still some room for improvement. Group III accounted for 32% of the hotels (9 hotels). They had the lowest pure technical efficiency and should focus on the usage and transformation of low-carbon technology. Group IV had seven hotels, accounting for 25% of the hotels. They should take full advantage of utilization efficiency of the existing resources because of their lowest scale efficiency. (3) By CCA, we could see the relationship between different indicators and the ordination axis, and all of the indicators including hotels' construction area, the number of rooms, the number of employees, coal consumption and water consumption were showing an increasing trend from left to right on the first axis, and the number of practitioners and the number of rooms were showing an increasing trend from bottom to top on the second axis. At the same time, from the fourth quadrant to the first and the second quadrants in the CCA figure, the types of hotels' carbon emission efficiency were transited gradually from group I to group II, group IV and group III. In the process of change, hotels' carbon emission efficiency was decreasing with obvious "arch effect". (4) The restriction of key indices to hotels' carbon emission efficiency was showed by CCA, and the limiting factors were distinguished, which pointed out the path to enhance hotels' carbon emission efficiency.

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    Spatial differentiation and influencing factors analysis of rural poverty at county scale: A case study of Shanyang county in Shaanxi province, China
    Peng WU, Tongsheng LI, Weimin LI
    2018, 37 (3):  593-606.  doi: 10.11821/dlyj201803011
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    Poverty is still remaining as the most prominent "short-board" in the Chinese economic development. The hardest and heaviest part of building well-off society in an all-around way lies in the rural construction, especially in the poverty-stricken area. The poverty alleviation and development in China is at the most critical stage, which requires more accurate recognition for the spatial differentiation of the rural poverty and its influencing factors, to make sure the exact targeting of the poverty alleviation policies and measures. This paper picked Shanyang, a key county in the poverty alleviation and development project of China, to explore the spatial pattern and type of the rural poverty of this county through the spatial autocorrelation analysis and grouping analysis. The stepwise regression, geographically weighted regression and Geodetector models were used to analyze the influencing factors of the rural poverty in this county, followed with the discussion on the spatial heterogeneity and interaction of the influencing effects. The following findings were concluded from the research: (1) The incidence of rural poverty in Shanyang noticeably clustered in space, forming 6 hot spots and 4 cold spots. In terms of rural poverty degree and spatial connectivity, the county was divided into low poverty area, mid poverty area and high poverty area. The space distribution was based on the regional poverty degree to facilitate a proper implementation of the poverty alleviation policies. (2) The major influencing factors responsible for the rural poverty in Shanyang included water network density, the distance to the nearest highway, proportion of dilapidated buildings, disposable income per rural capita, proportion of migrant workers and the proportion of rural households participating in the agricultural cooperatives. The influencing effects of all factors featured the spatial heterogeneity. Water network density and rural disposable income per capita were negatively correlated with the incidence of poverty while the rest factors showed a positive correlation. (3) The influence of the interaction between two factors appeared to be larger than that of the single factor. The interaction modes between major factors included bi-factor enhancement and nonlinear enhancement. Due to the interaction enhancement effects between poverty factors, the poverty alleviation policies shall be comprehensively matched to realize the expected target, along with a powerful poverty alleviation security system to ensure the full implementation.

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    Spatial pattern and spatio-temporal change of territory space in Hengduan Mountains region in recent 25 years
    Zhenqin SHI, Wei DENG, Shaoyao ZHANG
    2018, 37 (3):  607-621.  doi: 10.11821/dlyj201803012
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    Hengduan Mountains have a high ecological value and offer resources for a variety of ecological services. However, the sustainable development and management of territory space has been challenged by increased human activities in recent years. In this paper, we used the land use data of Hengduan Mountains in1990, 2000, 2010 and 2015 to analyze the quantity and structural changes and spatial pattern changes on various types of territory space at different elevations, and reveal the characteristics and influencing factors of recent changes in various territory space patterns. The results show that, the territory space in the Hengduan Mountains has relatively high altitudes and significant vertical differences. Within the ecological-production-living space schema, the ecological space dominates the Hengduan Mountains, while the production and living space are mainly distributed in the southeastern Yunnan plateau. During the last 25 years, the ecological-production-living space changes in the Hengduan Mountains have been gradually accelerated and the regional differences have become more prominent. The agricultural production space has continuously decreased, while the industrial and mining production space has increased rapidly in the last 15 years. The living space has steadily increased, and the ecological space has increased with fluctuations. The territory space pattern in the study region is greatly restricted by the natural factors such as altitude and slope. The implementation of China Western Development strategy and Grain to Green Project have favorably promoted the changes of territory space pattern in this region. At present, the territory space in the Hengduan Mountains still faces the problems of destruction of ecological environment by high-altitude industrial and mining exploitation, soil erosion on sloping cultivated land and natural disaster. In the future, the national spatial optimization development in the Hengduan Mountains needs to strictly control the production space of industrial and mining industries, ensure the ecological space, carry out the protection of basic farmland, implement the reforestation of sloping cultivated land gradually, and strive to strengthen the construction of disaster prevention and mitigation system in living space.

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    Spatial and temporal variations of spermafrost thickness in Heilongjiang province in recent years
    Ning WANG, Shuying ZANG, Lijuan ZHANG
    2018, 37 (3):  622-634.  doi: 10.11821/dlyj201803013
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    This study used the Mann-Kendall test, the smoothing T-test, and empirical orthogonal function analysis method to analyze the spatial and temporal variation characteristics of permafrost thickness in Heilongjiang province, with daily permafrost monitoring and temperature data obtained from 32 meteorological stations in the past 50 years (1961-2012). The results were as follows. (1) In the past 50 years, the permafrost thickness in Heilongjiang province decreased by 12.86 cm, at a rate of -0.53 cm/yr. An abrupt change occurred in 2001. (2) The spatial distribution of the permafrost thickness showed a tendency of being thick in the northern part and thin in the southern part, whereas in the central region the permafrost thickness was lower than that in other areas at the same latitude. The spatial variation showed that the permafrost thickness decreased faster in the southern part and at a slower rate in the northern part, while the central, western, and southeastern regions showed the opposite characteristics. The Yichun, Tieli, and Mohe observation points were more susceptible to permafrost change. (3) Temperature was the main factor influencing the permafrost thickness variations in the study area, and the correlation coefficient was -0.611. This main contribution of this article is that it reveals the spatial variation characteristics of permafrost thickness in Heilongjiang, and thus provides a suitable background for related research and various government programs.

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    Selection of environmental variables and their scales in multiple soil properties mapping: A case study in Heilongjiang Heshan Farm
    Jingjing SHI, Lin YANG, Canying ZENG, Axing ZHU, Chengzhi QIN, Peng LIANG
    2018, 37 (3):  635-646.  doi: 10.11821/dlyj201803014
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    Studying the relevant environmental variables with consideration of scales for different soil properties is meaningful to understand the generation and development of soil properties, and also necessary in multiple soil properties mapping and sampling. This study explored multiple soil properties' relevant environmental variables and their scales, and examined the impact of different environmental variables and their scales on the prediction of different soil properties. Our study area is Heshan Farm, and the target soil properties are topsoil clay content, sand content, silt content, topsoil organic matter content (SOM), and soil depth. One hundred and seventy-three multi-scale terrain variables were generated by changing neighborhood size for calculation. The single scale and multi-scale variables were ranked according to their variable importance calculated by Random Forest. Subsets 1 and 2 were selected from single scale and multi-scale variables respectively based on their variable importance with elimination of multi-collinearity. Subset 3 was taken as a reference subset and selected based on the expert knowledge. The selected subset 1 had little common with subset 3. This indicates that the environmental variables selected based on expert knowledge may be not the most important variables for the soil properties. Subset 2 had a high overlap with subset 3 though the scales were different for different environmental variables and soil properties. For the case of soil sand and silt, their relevant variables and scales were similar but quite different from soil clay's, and the SOM and soil depth had similar relevant variables. The mapping results based on the three subsets showed that using environmental variables in subset 1 was more accurate than using environmental variables in subset 3 for all soil properties except for sand content, the improvements of mean RMSEs were 1.8%~13.1%. Using environmental variables in subset 2 was more accurate than using environmental variables in subsets 1 and 3 for all the five soil properties, the improvements of mean RMSEs were 8.7%~16.5% and 7.8%~21.3%. It was shown that using reference variables with proper scales is more important than using top-ranked single scale variables for mapping.

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