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    Perspectives and Contention
  • Perspectives and Contention
    DENG Wei, ZHANG Shaoyao, ZHANG Hao, PENG Li, LIU Ying
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    From the perspective of the coupling of socioeconomic and natural sciences, transitional geospace is the composite zones between natural-socioeconomic system, highlighting the particularity and complexity of the regional system of human-nature relationship. In terms of the type, the mountainous transitional geospace, which we need to focus on and deepen its understanding and cognitionis, is the key areas for the high-quality development and management of modern territorial space in China, as well as one of the important issues of the frontiers of geographical research. In the light of the elaboration of the concept, connotation and attributes of transitional geospace from the perspective of the coupling of socioeconomic and natural systems, and referring to multidisciplinary concepts, theories and methods, inspired by the principle of color gradients, this study exploratively proposes a scientific research framework for transitional geospace based on the geocoding and decoding technologies, aiming to explain the socioeconomic-natural coupling evolutionary process and its mechanisms in transitional geospace, and to provide scientific decision guidance and basis for improving the territorial space function and optimizing its development pattern in the transitional geospace. It also has application values to enrich the explorations and practices for the research of human-nature relationship and regional systems.

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    LI Yifei, WANG Kaiyong, WANG Fuyuan
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    To classify administrative regions and implement different management policies accordingly is a common practice adopted in many countries. It is essential for big countries like China to divide different types of administrative regions in line with local conditions to achieve effective national governance. As an important demonstration of administrative divisions, the gradation of administrative regions, especially at the county and municipal levels, has long been an important means in the field of administrative management in China's history. This paper, based on the statistical data of counties and cities in China, used mathematical methods such as AHP and K-means cluster to propose the gradation of counties and cities. And a quantitative assessment of the feasibility and effectiveness of the gradation was conducted. Finally, based on the classification of administrative regions and the gradation of counties and cities, and the legal regulations of administrative divisions, the paper discussed the issue of the procedure and dynamic management of counties and cities' gradation. Results show that, the number of high-gradation counties and cities is relatively large, and the number of low-gradation counties and cities is relatively small. The internal differences of high-gradation counties and cities are larger than those of low-gradation ones. The geographical distribution of different gradations of counties and cities is uneven. It is feasible to classify counties and cities in practice. Thus, it is reasonable to classify counties and cities based on indicators such as population, geography, economy, and management difficulty. One possible method is to classify counties and cities at the provincial level and use proportion instead of absolute value. The goal of counties and cities' classification is to give different jurisdictions to different counties and cities. For the provinces with small difference and small number of counties and cities, they need special arrangements. The significance of the counties and cities' classification is to rationalize the management system of counties and cities and improve the management efficiency. Counties and cities' classification could unleash the vitality of local development and promote healthy competition. And counties and cities' classifications are of great significance for promoting the modernization of the national governance system and governance capacity.

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    MA Xiuxin, LIU Yaolin, LIU Yanfang, JIANG Ping, AN Zihao, ZHANG Xianghui
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    The existing research on the temporal heterogeneity across the urban-internal polycentric developments remains insufficient. To fill this research gap, we employed the relative minimum threshold approach to measure the intra-city morphological polycentricity in Chinese prefecture-level cities, 2005-2015, using the 1-km-grid population dataset. The hierarchical-cluster analysis was then adopted to induce the patterns of temporal variations in polycentricity. Finally, the mixed effect model is used to capture the temporal heterogeneity and explore the correlation factors of intra-city polycentricity during the focal period. The results showed that: (1) the multicenter structure of Chinese cities has been basically formed around 2010; (2) five evolution patterns were identified; (3) the urban-internal morphological polycentricity presented significant correlations with the geographic features, demographic characteristics, economic performance, infrastructures, and city size; (4) consistent with the classic urban structure theory, the evolution in urban China exhibited significant temporal variations and conformed to the diffusion-coalescence development pattern. The research findings and corresponding methodologies of the current research can help to advance the understanding of patterns of urban polycentric developments in urban China.

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    TIAN Junfeng, WANG Binyan, CHENG Lisha, WANG Shijun
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    In view of the typical regional development strategic areas such as Northeast China and West China, this paper constructs a policy-led interpretation framework for regional land use transition. Based on the empirical study of land use transition process in Northeast China from 1995 to 2015, this paper further explores and explains the regional land use transition mechanism guided by policy. The results show that: (1) There are two main paths for the regional land use transition guided by policy, namely, the socio-ecological feedback path under the policy guidance and the social-economic change path under the policy influence. Land scarcity and land intensification, ecological environment protection and policy intervention, regional function orientation and land use, economic modernization and urbanization, market and globalization, population growth and migration are the main factors leading to regional land use transition guided by policy. (2) From 1995 to 2015, the socio-economic development of Northeast China showed a process of transition and land use transition took place at the same time. The transition of regional land use is mainly manifested in the change of regional land quantity structure, the conversion relationship and intensity among different types of land, and the change of spatial structure of land use. (3) Empirical study on land use transition in Northeast China shows that the policy-led regional land use transition is the result of the comprehensive effect of the social-ecological feedback path under the policy guidance and the social-economic change path under the policy influence. There is a coupling and antagonistic process between the two paths. The former path affects the process of regional land use transition by influencing the supply of different types of land. The government's understanding of the importance of different resources determines the direction of its policy role and changes the land supply. The socio-ecological feedback under the guidance of policies determines the direction of regional land use transition. The latter path comes from the changes of regional socio-economic development. In this process, economic modernization, population growth and migration, market and globalization bring about changes in regional land use demand. Regional industrial development policy and urbanization policy affect the process of land use transition by changing the direction of regional development and accelerating the process of regional development. The socio-economic change under the influence of policies determines the speed and intensity of regional land use transition. The regional function orientation, as well as economic modernization and urbanization, are the two core factors leading to the regional land use transition under the policy guidance. We also have some other findings about the regional land use transition guided by policies. For example, the implementation of some inclination policies led to the unsustainable use of regional land. Therefore, how to improve the policy system and realize the transition of land use to sustainable development through policy guidance and policy coordination should be the focus of future research.

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    ZHANG Yanji, DENG Weitao, ZHAO Lizhen, LI Miaoyi
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    The influence mechanism as well as impact path of built environment on public health was still hidden in the black box, and the existing western fragment analysis mostly failed to consider the issue of residential self-selection, which would cause estimation bias. To solve this problem, this research did a sample survey in the core urbanized area of Fuzhou so as to identify the mediating variables between urban built environment and the physiological health of residents. In order to avoid self-selection bias, robustness test was focused on the subgroups living in Danwei, Fanggaifang, or public housing communities that were unable to choose their own house independently. By using data of social survey, point of interest, road network and according to the structural equation model, functional density and diversity, road network accessibility, image maintenance and management, and accessibility of sports facilities had positive relationships with self-assessed physical health through the mediating role of physical activities. The above three characteristics had indirect positive effects on leisure walking behavior via accumulating community social capital, diminishing criminal activity and evaluating the sense of living security, while the moderate to vigorous physical activity was directly positively influenced by road network accessibility, functional density and diversity at the macro scale. Improving the accessibility of community sports facilities can promote both leisure walking and moderate to vigorous physical activity at the same time. Through mediating effect of healthy dietary behavior and unhealthy dietary behavior, the accessibility of healthy food was strongly negatively correlated with the number of chronic diseases. Even if the interference of residential self-selection was controlled within the subgroups, the above five types of built environment characteristics still had significant impact on physiological health, which proved that the optimization of built environment was indeed an effective and proactive way to improve public health. According to the standardized total effect, the influence of sports facilities and healthy food accessibility on physiological health was the highest, and the influence of the other three built environments was similar and moderate. Therefore, it was necessary to perfect both sports environment and food environment, while we evaluate both hardware environment (increasing road network density and functional diversity) and software environment (improving image maintenance and management) in healthy urban planning. The limitation of this paper is that the analysis was based on cross-sectional data and subjective measurements of physical activities and health indicators, which remained to be improved.

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    GUO Yan, YANG Changming, ZHANG Yuyang
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    The "Xuannan culture", as an important part of Beijing history and culture, which formed in the Xuannan district of Beijing in the Qing Dynasty, was a kind of "hierarchic culture" with celebrities and scholars. From the "field" view, Xuannan district was a field of hierarchic culture. By extracting POI of the three kinds of core architectural culture landscape elements: 327 temples, 211 celebrity residences, 535 guild halls, which mainly bore the hierarchic culture of Xuannan district, this study analyzed the spatial distribution of the three types of "micro field" respectively and as a whole, as well as the relation and aggregation between two. Thus, it proactively explored the existence, scope and spatial characteristics of the core area of hierarchic culture of Xuannan as "sub-field", and the aggregation of the elements and the internal causes of its formation. The conclusions mainly include: (1) By using the average nearest neighbor calculation and spatial density analysis, we found that the core area of hierarchic culture was the "two-kidney" shaped area in the central and north-central part of the western outer city, which was close to the secular culture area, and its range was stable and had no absolute clear boundary. The locations of the core hierarchic and the secular culture areas reflected the relation of the two cultures: exclusive and dependent, infiltrative and complementary. (2) By using the overlapping analysis of core density, OD distance and the bivariate spatial correlation analysis, we concluded that the spatial characteristic of the core area of hierarchic culture was "chain type" of "three elements, and two gatherings". The first gathering was the relationship between the temples and the celebrity residences. The second was that between the celebrity residences and the guild halls. Through two cluster analyses, it is found that the hierarchical spatial structure of "center -- transition center" was formed in the core area of Xuannan hierarchic culture. (3) It is quantitatively verified that "the feeling of hometown" was the driving force of celebrity residences and guild halls gathering. Under the strategic positioning of Beijing "cultural center", this article lays a historical research foundation for the proposal of Xuannan culture protection and inheritance strategy. In the history and culture research field, this research has innovation and reference significance in perspective and method.

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    SHI Lei, CHEN Leyi, LI Yushuang
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    Clarifying the diversified spatial interaction in China's regional economic development is of great significance to explore the new concept of regional coordinated development in the new era. This paper constructs the spatial econometric model based on growth pole and central place theories, and studies the peer effects of urban areas in different income levels taking 260 prefecture-level cities in China as the research object, and explains the internal motive force of regional coordinated development from a new perspective. The results show that: (1) High-income cities have a driving effect on the economic growth of neighboring middle-income cities through positive peer effects, and have a dampening effect on the economic growth of neighboring trap cities through negative peer effects. The top-down radiation action between Chinese cities is not fully utilized. (2) Middle-income cities have positive peer effects on the economic growth of high-income cities, and trap cities have positive peer effects on the economic growth of middle-income cities, and there is a bottom-up economic growth promotion between our cities. (3) Economic growth between cities at equal income levels is mutually reinforced by positive peer effects. Further study finds that peer effects are largely due to the yardstick competition under decentralized fiscal system, and there is a significant heterogeneity in the effects of learning and competition mechanisms within cities with different income levels. Finally, the policy enlightenment of realizing regional coordinated development is put forward from the aspects of implementing a multi-central space strategy, building a new type of urban cooperation model, strengthening the infrastructure construction, and improving the performance evaluation system.

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    MA Shuang, ZENG Gang, ZHANG Yiou
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    Ignoring the realistic basis and blindly pursuing new industries have become a common phenomenon in Chinese cities. Scholars have generally called for the implementation of regional capacity-based development policies, taking into account regional realities and industrial base, to avoid "one size fits all", repeated construction and vicious competition. Based on the patent data of the State Intellectual Property Office (SIPO), this paper describes the spatial-temporal evolution characteristics of technology relatedness and complexity of Chinese cities from 1987 to 2016, and estimates the impact of technology relatedness and complexity on regional technology introduction and technology growth. The results show that: (1) The dynamic of technology entry and exit in the eastern region is stronger than that of the central and western regions. The correlation analysis between relatedness and technology entry and exit shows that technology with high relatedness is more likely to enter the region. In contrast, technologies are more likely to exit if they do not have strong local technology linkages. (2) From the view of technological relatedness and complexity, technological evolution in eastern coastal areas is more dependent on the technological relatedness, and technological complexity has experienced tremendous growth, while technological relatedness and complexity in the central and western regions have changed little, and technological development in Chinese cities generally presents path-dependent characteristics. (3) Technological relatedness has been playing a significant role in promoting the entry and growth of new technologies. When technology with high complexity is introduced, if it has a high relatedness with the existing technological foundation of the region, it will play a significant role in promoting regional technological progress; on the contrary, even if the blind introduction of complex technology will not have a significant impact on regional technological progress. Based on the relatedness and complexity, this paper divides the technology development paths into four types: The policy of "bright road" means low risk and high benefit, when technologies are expected to exceed average returns under relatively low risk. In contrast, technological development with high risk and low benefit are unlikely to catch and raise value, we therefore refer to such a policy as "dead end". The "road exploration" policy means high risk and high benefit, which aims to develop new and original technology to realize path creation. "Slow Road" policy means driving safely forward in the existing low-level technology path. The framework of regional diversification development can provide a reference for decision makers to weigh and choose the path of technological development.

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    LIU Hao, MA Lin, LI Guoping
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    Based on the data envelopment analysis, taking capital, land, and labor as the input factors, and non-agricultural GDP as the output factor, the paper quantified the urban economic efficiency of cities at the county level and above in China, and identified its main factors by the panel binary selection model. The results show that urban technical efficiency is higher in eastern China than that in western China, and it has a certain spatial spillover globally. But the spillover effect of the urban scale efficiency is much smaller, and its high scale efficiency is mainly close to that of the small towns around large cities, especially in the Bohai Rim region, the Yangtze River Delta region and the Pearl River Delta region. Secondly, based on the Malmquist index, China's urban technological efficiency changes and urban economic efficiency changes have obvious local spatial characteristics, that is, economically developing regions are better than the developed regions, and small cities are better than large cities. And the cities with high urban scale efficiency changes are mainly concentrated in the major urbanization areas such as the Bohai Rim region, the Pearl River Delta region and the Yangtze River Delta region, and large cities have faster growth than small cities. Thirdly, there is obvious spatial heterogeneity in China's urban economic efficiency fluctuations. And urbanization level, industrial pollution discharge, government scale, science, and technology investment, fiscal policy and social development are the main positive factors affecting urban economic efficiency fluctuations, while real estate development investment has no obvious influence. Besides, with the continuous growth of urban economic scale and the decreasing scale of urban construction land, urban economic efficiency will gradually rise. When it reaches a certain threshold, urban economic efficiency will decline, and the large-scale urban sprawl at this stage does not bring about a substantial increase in urban economic efficiency.

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    WANG Zhao, LI Tao, YANG Shan
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    The relationship between tourist flow and tourism economic efficiency has been an important topic of research in the fields of tourism economics and tourism geography. Existing studies tend to treat them as independent subjects. In particular, few studies have investigated the spatial relationship between them. This paper aims to fill the research gap through a comprehensive analysis of inter-provincial inbound tourist flows. The paper first constructs a coupling framework between tourist distribution superiority and tourism economic efficiency. It then measures the comparative superiority and economic efficiency for the 31 provincial-level regions to reveal the temporal and spatial patterns. Several conclusions can be dawn as follows. First, inbound tourist distribution superiority shows significant differentiations at the provincial level. During the 11-year period of 2005-2016, relative superiority changed most significantly. Beijing, Shanghai, Guangdong and Sichuan have obvious advantages in attracting inbound tourists. Second, the average economic efficiency increased from 0.485 to 0.520, and the proportion of the 1st- and 5th-level provincial-level regions increased from 29.03% to 48.39%, indicating an obvious rise as well as a polarization trend. By 2016, an 'S'-shaped spatial distribution for high-level efficiency provinces had emerged. Third, the spatial relationship between distribution superiority and efficiency was altered. Specifically, the number of high-level and medium-level coordination (H-H and M-M) areas increased, while that of low-level coordination (L-L) areas decreased. Meanwhile, the number of imbalanced tourist destinations (H-L or L-H) increased. Fourth, tourist distribution superiority and tourism economic efficiency are two key variables that are closely interrelated. An imbalanced relationship between distribution superiority and efficiency affects the overall competitiveness of regional tourism. Thus it is suggested that more resources should be allocated to the weak coupling system to strengthen the relationship between tourist distribution superiority and economic efficiency. More importantly, varying strategies should be implemented for each tourist destination according to their coupling state.

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    GUO Wen, HUANG Zhenfang
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    In the context of mobility brought about by tourism, capitalization intervention and tourism utilization of the "home" space in traditional ethnic Zhudi village in China have triggered the multi-dimensional production of space, the difference of identity and the vicissitude of human-land relationship of the "home" space of Mosuo people in the village, and also prompted people's reflection on the development of tourism and production of the "home" space in the village in the transitional period to an urgent problem to be concerned and solved. By means of field investigation, participating observation and in-depth interview, this paper studied the multi-dimensional production and identity construction of Mosuo people's "home" space in the study village under the background of tourism. The religious beliefs and the circulation in different periods of Mosuo people in Zhudi village regulate the natural, worldview and moral outlooks of Mosuo villagers in their daily space practice reflecting the self-consistency of spirits and objects and the unity of body and mind. The "home" space of Mosuo people in Zhudi village is systematic, which is reflected in different scales of spatial circles of village outer layer, village layer, home site layer, grandmother's house and body layer. Its spatial order and significance involve abundant natural ecological consciousness and human-land relationship. Structural forces such as capital, power and consumption, which are mediated by tourism, interweave and influence each other, resulting in multi-dimensional production of the traditional space of the Mosuo people's "home" in Zhudi village, bringing about the micro-geospatial relationship of the "home", the social and cultural significance and the geographical remodeling of the human-land relationship, and having the interactive dialectics of multi-dimensional spatial level. With the multi-dimensional production and micro-geographic remodeling of "home" space in the village, the construction of pre-factor identity characterized by humanism and the construction of consequential identity characterized by structuralism and the construction of "intermediate" identity characterized by "value identification, emotional disapproval" and "value disapproval, emotional identification" have emerged. The identity construction of the tourismized practice of home space of Mosuo people implies and reflects the villagers' recognition of "homestead" and "home country". The essence of tourismized "home" space tourism is the practice process of traditional national space capitalization. Ultimately, it is the choice of development path and mode by "locals" in the new era. It is also necessary to adjust the contradiction between "home" space capitalization and development alienation. In addition, the case analysis of the micro-geographic space of "home" in Zhudi village enriches the existing theoretical research achievements of "home" in academic circles.

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    HUANG Qingyan, BAI Kai
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    The pattern of "going to the town to do business" identified by Yuanjia village stands out as a paradigm of translocal expansion and development. Taking this pattern of Yuanjia village as an example, this paper, based on the participatory observation of daily life in the stores and in-depth interviews with store operators, consumers and managers, explores the translocal rurality production and presentation in the village and examines how it is constructed and evolved in the process of urbanization and modernization. The results of the research are as follows: (1) The rurality of Yuanjia village is embedded in the process of the development of the village and presents a diachronic change, that is, the rurality is not the result of solidification, but a dynamic evolution process. (2) Driven by the upgrading of rural development, the translocal production process of Yuanjia village is a flow process of rural material, human, institution and other factors across regional boundaries, which is also the integration of the multiple relationships of consanguinity, industry network and region network between the village and the city. (3) The translocal process of Yuanjia village presents the rurality with three-dimensional integration of rural life, rural production and rural social relations through the expansion of food production. The continuation of rurality in urban space is completed by the expansion of power and capital, the transfer of standardized production and the construction of symbolized space. (4) Rurality is socially constructed, emphasizing the significance creation of different groups to the countryside. The phenomenon of Yuanjia village's "going to the town to do business" transcends the rural boundary, but it has a deeper and stronger connection with agriculture, land and village collective, which strongly retorts the conclusion of "the end of the village" and "the end of the rurality". The study suggests that emphases on understanding rurality from the perspective of pluralism, dynamics and integration will help to experience more authentic rurality in the complicated process of rural revitalization transformation, and provide a new thinking for the rural theoretical research and practical exploration.

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    LI Hongbo, LIU Meidou, HU Xiaoliang, CHEN Xiaohua
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    In order to adapt to the context of rural population contraction caused by urbanization, the local government has put forward a series of policies guiding rural space shrinkage development in southern Jiangsu. Based on the statistics data of rural population and the spatial vector data of rural land use in 2005 and 2017, this paper took Changshu city as the research area, then carried out a quantitative analysis of the trend of rural human settlement space change in different scales of county, town and village from four aspects, including rural population size, rural residential land use, internal structure and expansion direction. Finally, this paper identified different types and influencing factors of rural human settlement space change. Several conclusions were obtained as follows: (1) On the county scale, the rural human activity in Changshu was continually shrinking, but the rural human settlement space was expanding, especially in the south & southwest directions. Moreover, rural land use internal structure was becoming more non-agricultural, and overall state was diluted and extensive. (2) On the town & village scales, there were differences in change characteristics on different scales. Specifically, the rural human activity was in both contraction and expansion, and exhibited differently on different scales, which was more significant on the village scale. (3) The paper identified five types of changes in rural human settlements space of Changshu city, namely, urbanization oriented, industrialization oriented, transportation oriented, industrialization-transportation oriented and policy oriented, as well as explored its driving factors on a macro level. In short, the rural human settlement space change of Changshu city is driven by four factors containing urbanization, industry, transportation and policy. Also, this study could expand the multi-scale analysis method of rural Smart Decline, and even introduce a new theoretical perspective for the rural space transformation research.

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    WANG Yahui, LI Xiubin, XIN Liangjie
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    How reliable are cultivated land assets as old-age security for Chinese farmers is a scientific issue that needs to be urgently solved in the research field of land use change and rural pension system. To give a scientific judgment on the function of cultivated land as old-age security in the new era and provide a reference for improving the rural old-age security system, this paper regards the cultivated land with the contracting right as an asset for farm households, and systematically reveals the spatiotemporal evolution in the old-age security function of cultivated land asset from the national and provincial levels based on large-scale household survey data from the Rural Permanent Observation Sites (RPOS) conducted by the Ministry of Agriculture from 1986 to 2015. The results show that: (1) At the national level, compared with the constant price of 1986, the value of old-age security per capita cultivated land has dropped from 550 yuan to 150 yuan in the past 30 years, and the decline rate reached 72% during the study period. In the 1980s, cultivated land assets could meet the old-age expenditures of the elderly; but after 1994, the value of cultivated land as old-age security could not support the consumption of the elderly, and the gap in the demand for old-age security continued to expand. (2) At the interprovincial level, the value of cultivated land as the old-age security in all provincial-level regions was in a downward trend during the study period, and there were significant differences among provinces. In recent years, the contribution rate of the old-age security to the demand for old-age care has been declining, and the gap in the demand for old-age care has been expanding. The provinces along the Southeast Coast and the Yangtze River are the most prominent. Nowadays, cultivated land contract that began in the 1980s has lost its basic arguments, and the theory on social protection of cultivated land needs to be re-examined. The old-age consumption of rural residents can no longer count on a small amount of cultivated land with contracting rights for farmers and the old-age security must be built on the public pension security system. The government should focus on strengthening the capacity of rural old-age services.

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    DENG Qingqing, LI Erling, REN Shixin
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    The environmental effect of agricultural agglomeration is more complicated than that of other industries, but there is a deficiency of the research on it. This study calculated the level of agricultural agglomeration and the emissions of agricultural non-point pollutants in Chinese prefecture-level cities by using the panel data of these cities on the basis of the theoretical analysis. Then we investigated the spatial and temporal characteristics of agricultural agglomeration and agricultural non-point source pollution and the threshold effect of agricultural agglomeration level on agricultural non-point source pollution based on GIS spatial analysis and econometric model. The main conclusions can be drawn as follows: (1) Agricultural agglomeration and agricultural non-point source pollution of COD, TN and TP show different characteristics in temporal variation, spatial distribution, spatial correlation and spatial trends. (2) Agricultural agglomeration has single threshold effect on COD, TN and TP pollution, and positive correlation with them. When the level of agricultural agglomeration is below the threshold value, it contributes to agricultural pollution significantly, and as the level of agglomeration becomes higher than the threshold value, the situation of rapid pollution will be mitigated. (3) The change from agricultural agglomeration to emissions of three agricultural non-point source pollutants develops in two stages. This change depends on the intensification and restriction of the scale effect, structure effect, technical effect, social effect and cumulative effect on the emissions of agricultural non-point source pollution produced by agricultural agglomeration and it is reflected in the concrete agricultural production behavior. With the increase of agricultural agglomeration, the effect of each effect is obvious and the level of pollution increases significantly, however, the inhibition ability of pollution emission is improved and the external effect of negative environment is weakened at the stage of crossing the threshold. (4) The agricultural economic level and agricultural production conditions aggravate the COD, TN and TP agricultural non-point source pollution to some extent; the structure of animal husbandry industry and environmental regulation have a positive correlation with COD and TP agricultural non-point source pollution; the improvement of producer quality can affect farmers' production behavior and improve the agricultural environment. (5) The effect of agricultural agglomeration on pollution reduction of COD agricultural non-point source pollution is weak and COD agricultural non-point source pollution is more serious and mainly from animal husbandry.

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    ZHANG Lijuan, LI Yanhong, REN Han, WANG Liyuan, ZHU Wenbo, ZHU Lianqi
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    Climate plays a major role in biodiversity and vegetation types, and vegetation types and distribution reflect the regional climate. A rise in global mean temperature will lead to changes of global precipitation pattern, vegetation types and their distribution. However vegetation can react to climate change by genetic adaption and ecological buffering; hence, there is a temporal hysteresis in the response of vegetation to climate change. It has some limitations to study the northern boundary of subtropical zone and its movement only by climate indicators. Therefore, we introduced a species distribution model to conduct species potential distribution and reflect the movement of northern boundary of subtropical zone. In this study, we chose Cyclobalanopsis glauca, a typical subtropical evergreen broadleaved tree, to investigate the distribution pattern of Cyclobalanopsis glauca under climate warming and its implication for the northern boundary movement of subtropical zone. Based on 10 high resolution environmental data under current and future climate scenarios (RCP2.6 and RCP8.5), we modeled the present and future suitable habitats for Cyclobalanopsis glauca by the maximum entropy model (Maxent) and identified the distribution shifts by centroid movement under two climate change scenarios. The results showed that the area under the receiver operating characteristic curve value was 0.932, indicating that the prediction of the potential distribution for Cyclobalanopsis glauca was reliable. Results from the Jackknife test showed that the main environmental variables affecting the distribution of Cyclobalanopsis glauca were annual precipitation, precipitation of coldest quarter, temperature annual range and minimum temperature of coldest month, with the cumulative contribution of 94.2%. Currently, the potential suitable habitats areas for Cyclobalanopsis glauca encompassed 17.44×10 5 km 2, mainly located between 18°N-33°N and 91°N-121°E, the high potential habitats account for 25%, and the centroid of the current habitats was located in Yanling in Hunan province (26°31′12″N, 113°41′24″E). Under the two future climate change scenarios, the total suitable area of Cyclobalanopsis glauca would increase in the 2050s, the area of new habitats under RCP2.6 and RCP8.5 is 3.2×10 5 km 2; the high potential habitats account for 32% under RCP2.6, however it only accounts for 26% under RCP8.5. Furthermore, the northern boundary of the total suitable area would shift to higher latitudes, and the centroid of the total suitable area would shift to the northwest in the future, indicating that the northern boundary of subtropical zone of China would move poleward of 1° under climate change in the 2050s.